Patent Application
20210017499
This application claims priority to Korean Patent Application No. 10-2019-0087134 filed on Jul. 18, 2019, which is incorporated by reference in its entirety herein.
The present invention relates to a preparation method of cancer stem cell spheroids or a kit for preparing cancer stem cell spheroids. In addition, it relates to a method of screening of drugs for treating cancer cell resistance using cancer stem cell spheroids prepared by the method of producing or kit.
Cancer stem cells (CSCs or tumor-initiating cells: TIC) have many features similar to normal stem cells, such as self-regenerative ability, endogenous drug resistance and differentiation, and the like. Since cancer cells similar to stem cells have been discovered in acute myeloid leukemia, there is increasing evidence that a small number of cancer stem cells are present in tumor aggregates primarily responsible for tumor recurrence and drug resistance. Therefore, cancer stem cells have attracted considerable attention in the field of cancer research and drug resistance.
Cancer stem cells are generally isolated from patient-derived tumor tissue based on cancer stem cell surface markers. However, the supply of the patient-derived tumor tissue is limited, and only a small amount of cancer stem cells can be isolated, which makes it difficult to obtain cancer stem cells. Alternatively, attempts have been made to separate cancer stem cells from existing cancer cell lines, but since cancer stem cells are contained less than 1 to 2% in the cancer cell line, it is not practical to secure a sufficient amount of cancer stem cells (Cell 144, 646-674 (2011)). In addition, since the three-dimensional structure of cancer cells can better represent the tumor environment than the two-dimensional monolayer structure, considerable interest is currently shown in developing a method for promoting formation of cancer cells. The spheroid, which is used for drug screening or efficacy testing, is currently produced by a method for inserting cells into a hole of a hydrophilic ULA (ultra-low-attachment) surface, a concave agarose gel (U-bottom) or a hanging-drop cell substrate, and the like. However, even the spheroid produced by the method does not sufficiently contain cancer stem cells. In this situation, there is a need to develop a simple method for producing cancer stem cell spheroids having cancer-formation ability in a human cancer cell line.
Accordingly, the present inventors have tried to develop a method for producing cancer stem cell spheroids, and as a result, they have established a method for producing cancer stem cell spheroids using a cell culture substrate comprising a siloxane polymer and a medium comprising albumin, thereby completing the present invention.
One embodiment of the present invention is to provide a method for preparing a stem cell spheroid from a cancer cell, comprising culturing a cancer cell using a medium for cell culture comprising albumin.
The albumin may be a use for inducing cancer cells into cancer stem cells, a use for inducing cancer cells into a spheroid, or a use for inducing cancer cells into cancer stem cell spheroids.
The cancer cell may be cultured on a cell culture substrate comprising a siloxane polymer.
The cell culture substrate comprising a siloxane polymer may be a use for inducing cancer cells into cancer stem cells, a use for inducing cancer cells into spheroids, or a use for inducing cancer cells into cancer stem cell spheroids.
Another embodiment of the present invention is to provide a kit for preparing cancer stem cell spheroids, comprising a cell culture substrate and a medium for cell culture.
The cell culture substrate may comprise a siloxane polymer, and the medium for cell culture may comprise albumin, and the siloxane polymer or the albumin may be a use for inducing a cancer cell into cancer stem cells, a use for inducing a cancer cell into a spheroid, or a use for inducing a cancer cell into cancer stem cell spheroids.
Other one embodiment of the present invention is to provide a method for screening of drugs for treating cancer cell resistance, comprising (a) preparing cancer stem cell spheroids by the method for preparation of cancer stem cell spheroids; (b) treating a candidate substance for treating cancer cell resistance to the cancer stem cell spheroid of the (a) step; and (c) comparing the cancer stem cell spheroid group in which the candidate substance for treating cancer cell resistance of the (b) step and the control group in which the candidate substance for treating cancer cell resistance is untreated.
This is specifically described as follows. Meanwhile, each description and embodiment disclosed in the present application may be applied to each other description and embodiment. In other words, all combinations of various elements disclosed in the present application fall within the scope of the present application. In addition, the scope of the present application is not considered to be limited by the specific description disclosed below.
As one aspect to achieve the objects of the present invention, a composition for inducing cancer stem cells from cancer cells, comprising a medium for cell culture containing albumin is provided.
The albumin may be (1) a use for inducing the cancer cells into cancer stem cells, (2) a use for inducing the cancer cell into a spheroid, or (3) a use for inducing the cancer cell into cancer stem cell spheroids.
As another aspect to achieve the objects of the present invention, a method for preparing cancer stem cells from cancer cells, comprising culturing a cancer cell using a composition for inducing cancer stem cells from cancer cells, comprising a medium for cell culture containing albumin is provided.
The cancer cell may be cultured on a cell culture substrate, and the cell culture substrate may comprise a siloxane polymer.
The cell culture substrate comprising the siloxane polymer may be (1) a use for inducing the cancer cells into cancer stem cells, (2) a use for inducing the cancer cell into a spheroid, or (3) a use for inducing the cancer cells into cancer stem cell spheroids.
As other aspect to achieve the objects of the present invention, a kit for preparing cancer stem cell spheroids, comprising a cell culture substrate, and a composition for inducing cancer stem cells from a cancer cell, comprising a medium for cell culture containing albumin, wherein the cell culture substrate comprise a siloxane polymer and the medium comprises albumin, is provided.
As other aspect to achieve the objects of the present invention, a method of screening of drugs for treating cancer cell resistance, comprising preparing cancer stem cell spheroids; treating a candidate substance for treating cancer cell resistance to the cancer stem cell spheroid; and comparing cancer stem cell spheroids group in which the candidate substance for treating cancer cell resistance is treated and a control group in which the candidate substance for treating cancer cell resistance is not treated is provided.
The present inventors have found that when a cancer cell is cultured in a medium comprising albumin, on a cell culture substrate comprising a polymer formed by a siloxane compound, a three-dimensional cancer stem cell spheroid like in vivo environment, which completely has characteristics of the cancer stem cell, can be prepared with high yield, thereby providing the present invention.
Hereinafter, the present invention will be described in more detail.
According to one embodiment of the present invention, it relates to a method for preparation of cancer stem cells, comprising culturing a cancer cell on a cell culture substrate, comprising a siloxane polymer. The culturing a cancer cell may be culturing the cancer cell using a medium for cell culture comprising albumin. The cancer cell is a general cancer cell which does not have characteristics of the caner stem cell, and after the culturing, it has characteristics of the cancer stem cell (for example, expression of cancer stem cell marker genes, in vivo cancer-formation ability, drug resistance, cell migration or cell penetration, etc.). Therefore, the culturing a cancer cell may be culturing the cancer cell using a composition for inducing cancer stem cells from the cancer cells, and the composition for inducing cancer stem cells from the cancer cells may comprise a medium for cell culture comprising albumin.
The medium for cell culture may further comprise amino acids, vitamins, antioxidants, trace elements, proteins, collagen precursors, and the like. The amino acid may include glycine, histidine, isoleucine, methionine, phenylalanine, proline, hydroxyproline, serine, threonine, tryptophan, tyrosine, valine, etc., but not limited thereto, and the amino acid may be L-type amino acid or D-type amino acid. The vitamin may include thiamine, ascorbic acid, etc., but not limited thereto. The antioxidants may include glutathione, but not limited thereto. The trace elemets may include Ag+, Al3+, Ba2+, Cd2+, Co2+, Ge4+, Se4+, Br−, I−, F−, Mn2+, Si4+, V5+, Mo6+, Ni2+, Rb+, Sn2+, Zr4+, etc, but not limited thereto. The proteins may include transferrine, insulin, lipid-rich albumin (for example, AlbuMAX, etc.), but are not limited thereto. The collagen precursor may include L-proline, L-hydroxyproline, ascorbic acid, but not limited thereto.
As one aspect to achieve the objects of the present invention, a method for producing cancer stem cells from cancer cells, comprising culturing cancer cells using a composition for inducing cancer stem cells from cancer cells, comprising a medium for cell culture containing albumin is provided.
The culturing cancer cells using a composition for inducing cancer stem cells from cancer cells, comprising a medium for cell culture containing albumin is culturing an isolated cancer cell using a composition comprising a medium for cell culture comprising albumin, and the culturing may be performed on a cell culture substrate comprising a siloxane polymer.
When the cell culture substrate is a linear siloxane substrate, as a spheroid may not be formed when culturing a cancer cell using a medium for cell culture comprising albumin (FBS) (Example 7-3), it is inferred that the culture medium also affects spheroid formation in addition to surface functional stimuli of the substrate when cancer stem cell spheroids are prepared from a cancer cell using the linear siloxane substrate.
The cancer stem cell spheroid may be formed within 240 hours, within 20 hours, within 180 hours, within 150 hours, within 120 hours, within 110 hours, within 100 hours, within 96 hours, within 90 hours, within 84 hours, within 80 hours, within 72 hours, within 70 hours, within 60 hours, within 50 hours, within 40 hours, within 30 hours, within 24 hours, within 20 hours, within 12 hours, within 10 hours, or within 5 hours, after the start of culturing a cancer cell.
The term of the present invention, “cancer cell” or “isolated cancer cell” may be a cell derived from a human or a cell derived from various individuals except for humans, but not limited thereto. In addition, the isolated cancer cell may include all of in vivo or in vitro cells, but not limited thereto. Specifically, the isolated cancer cell may be specifically a cell derived from various tissues of humans, and may be a cancer cell derived from ovarian cancer, breast cancer, liver cancer, brain cancer, colorectal cancer, prostate cancer, cervical cancer, lung cancer, stomach cancer, skin cancer, pancreatic cancer, oral cancer, rectal cancer, laryngeal cancer, thyroid cancer, parathyroid cancer, colon cancer, bladder cancer, peritoneal carcinoma, adrenal cancer, tongue cancer, small intestine cancer, esophageal cancer, renal pelvis cancer, renal cancer, heart cancer, duodenal cancer, ureteral cancer, urethral cancer, pharynx cancer, vaginal cancer, tonsil cancer, anal cancer, pleura cancer, thymic carcinoma or nasopharyngeal carcinoma, but not limited thereto, and it includes all cancer cells which can be used for the objects of the present invention, and includes all primary cultured cells isolated by biopsy from cancer tissue, or established cell lines, but not limited thereto.
In addition, to confirm the cancer cell, a cancer cell marker may be used. Specifically, as the marker, AFP (Alpha-fetoprotein), CA15-3, CA27-29, CA19-9, CA-125, Calcitonin, Calretinin, CD34, CD117, Desmin, inhibin, Myo D1, NSE (neuronspecific enolase), PLAP (placental alkaline phosphatase) or PSA (prostatespecific antigen), or the like may be used, but not limited thereto.
The term of the present invention, “siloxane compound” is a compound comprising a siloxane group (Si—O bond) and is intended to include all siloxane monomers or siloxane polymers. The “siloxane polymer” means a polymer comprising a siloxane group as a repeated unit, and for example, it may include a linear siloxane polymer or cyclic siloxane polymer. The siloxane monomer or the siloxane polymer may be a compound having chemical formula 1, and may include a polymer having chemical formula 2 of the cyclic siloxane, and the like.
In the chemical formula 1,
R1 to R8 may be independently of each other hydrogen, C1-10 alkyl, C2-10 alkenyl, C5-14 heterocycle, C3-10 cycloalkyl or C3-10 cycloalkenyl, and n is an integer of 0 to 100,000. For example, the R1 to R8 may be independently of each other hydrogen, methyl, ethyl, propyl, ethylene, propylene, vinyl group, and the like, but not limited thereto.
According to one embodiment of the present invention, the linear siloxane compound may be at least one selected from the group consisting of dimethylsiloxane (DMS), tetramethyldisiloxane (TMDS), hexavinyldisiloxane, hexamethyldisiloxane, octamethyltrisiloxane, dodecamethylpentatetrasiloxane, tetradecamethylhexasiloxane, methylphenylsiloxane, diphenylsiloxane and phenyltrimethicone, and the linear siloxane polymer may be formed as the linear siloxane compound is polymerized.
According to one embodiment of the present invention, the siloxane polymer may be a polymer formed by polymerization of a base compound using a curing agent, and the base compound and the curing agent may be polymerized at a ratio of 100:1 to 1:100, 100:1 to 1:80, 100:1 to 1:50, 100:1 to 1:30, 100:1 to 1:20, 100:1 to 1:15, 100:1 to 1:10, 80:1 to 1:100, 80:1 to 1:80, 80:1 to 1:50, 80:1 to 1:30, 80:1 to 1:20, 80:1 to 1:15, 80:1 to 1:10, 60:1 to 1:100, 60:1 to 1:90, 60:1 to 1:80, 60:1 to 1:70, 60:1 to 1:60, 60:1 to 1:50, 60:1 to 1:40, 60:1 to 1:30, 60:1 to 1:20, 60:1 to 1:15, 60:1 to 1:10, 50:1 to 1:100, 50:1 to 1:90, 50:1 to 1:80, 50:1 to 1:70, 50:1 to 1:60, 50:1 to 1:50, 50:1 to 1:40, 50:1 to 1:30, 50:1 to 1:20, 50:1 to 1:15, or 50:1 to 1:10, but not limited thereto.
The siloxane polymer according to one embodiment of the present invention may be a cross-linked siloxane compound, and may be a cross-linked monomer of at least 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more, but not limited thereto, Specifically, the siloxane polymer may be water-insoluble as at least 1% or more of siloxane compound polymer is cross-linked. For example, in the chemical formula 1, R1 to R8 may be independently of each other linear siloxane compound or siloxane polymer, and therefore, the compound of chemical formula 1 may be a siloxane polymer formed as cross-linked.
The base compound for preparing a siloxane polymer may be the siloxane compound represented by chemical formula 1, for example, siloxane oligomer, dimethylsiloxane, tetram ethyl di siloxane, hexavinyldisiloxane, hexam ethyldisiloxane, octamethyltrisiloxane, trialkoxysiloxane, or tetraalkoxysiloxane, or the like, and the curing agent may be a siloxane cross-linker, a metal catalyst (platinum catalyst, ruthenium catalyst, etc.), hexamethylenetetramine, ammonia (NH3) or hydrogen chloride (HCl), or the like.
The siloxane compound according to one embodiment of the present invention may be a cyclic siloxane compound or cyclosiloxane polymer, and is used to include compounds which have a cyclosiloxane structure as a basic structure, and has a functional group (for example, alkyl group, alkenyl group, etc.) at the position of its silicon atom. According to one embodiment of the present invention, the cyclosiloxane compound is represented by the following chemical formula 2.
In the formula, A is
(n=an integer of 1-8);
R1 and R2 are independently of each other hydrogen or C2-10 alkenyl with the proviso that at least two positions of R1 are C2-10 alkenyl; and
R2 is independently of each other hydrogen, C1-10 alkyl, C2-10 alkenyl, halo group, metal element, C5-14 heterocycle, C3-10 cycloalkyl or C3-10 cycloalkenyl.
The term of the present invention, “alkyl” means a straight-chain or branched-chain, unsubstituted or substituted, saturated hydrocarbon group, and for example, includes methyl, ethyl, propyl, isobutyl, pentyl or hexyl, and the like. C1-C10 alkyl means an alkyl group having an alkyl unit of 1 to 10 carbon atoms, and when C1-C10 alkyl is substituted, the number of carbon atoms of the substituent is not comprised. Herein, C1-C10 alkyl may be C1-C8 alkyl, C1-C7 alkyl or C1-C6 alkyl.
The term of the present invention, “alkenyl” represents a straight-chain or branched-chain, unsubstituted or substituted, unsaturated hydrocarbon group having designated carbon atoms, and for example, includes vinyl, propenyl, allyl, isopropenyl, butenyl, isobutenyl, t-butenyl, n-pentenyl, and n-hexenyl. C2-C10 alkenyl means an alkenyl group having an alkenyl unit of 1 to 10 carbon atoms, and when C2-C10 alkenyl is substituted, the number of carbon atoms of the substituent is not comprised.
According to one embodiment of the present invention, herein, C2-10 alkenyl is C2-8 alkenyl, C2-6 alkenyl, C2-5 alkenyl, C2-4 alkenyl or C2-3 alkenyl. According to one embodiment of the present invention, at least three parts of the R1 is C2-10 alkenyl. According to one embodiment of the present invention, the cyclosiloxane has n+1 or n+2 of C2-10 alkenyl at the R1 position. For example, when n is 2, the compound of chemical formula 1 becomes a cyclotetrasioloxane having 3 or 4 C2-10 alkenyls at the R1 position. This alkenyl group is involved in polymerization.
The term of the present invention, “halo” represents a halogen element, and for example, includes flouro, chloro, bromo and iodo. The term of the present invention, “metal element” means an element which makes metallic simple substance such as alkali metal elements (Li, Na, K, Rb, Cs, Fr), alkali earth metal elements (Ca, Sr, Ba, Ra), aluminum family elements (Al, Ga, In, Tl), tin family elements (Sn, Pb), coinage metal elements (Cu, Ag, Au), zinc family elements (Zn, Cd, Hg), rare earth elements (Sc, Y, 57-71), titanium family elements (Ti, Zr, Hf), vanadium family elements (V, Nb, Ta), chrome family elements (Cr, Mo, W), manganese family elements (Mn, Tc, Re), iron family elements (Fe, Co, Ni), platinum family elements (Ru, Rh, Pd, Os, Ir, Pt) and actinide elements (89-103), and the like.
The term of the present invention, “heterocycle” means a partially or completely saturated, monocycle type or bicycle type of 5 to 14 membered heterocycle ring. N, O and S are examples of heteroatoms. Pyrrole, furan, thiophene, imidazole, pyrazole, oxazole, isoxazole, thiazole, isothiazole, tetrazole, 1,2,3,5-oxathiadiazole-2-oxide, triazolone, oxadiaxolone, isoxazolone, oxadiazolidine dione, 3-hydroxypyro-2,4-dione, 5-oxo-1,2,4-thiadiazole, pyridine, pyrazine, pyrimidine, indole, isoindole, indazole, phthalazine, quinoline, isoquinoline, quinoxaline, quinazoline, cinnoline and carboline are examples of C5-14 heterocycles.
The term of the present invention, “cycloalkyl” means a cyclic hydrocarbon radical, and this includes cyclopropyl, cyclobutyl and cyclopentyl. C3-10 cycloalkyl means a cycloalkyl having 3-10 carbon atoms which form a ring structure, and when C3-10 cycloalkyl is substituted, the number of carbon atoms of the substituent is not comprised.
According to one embodiment of the present invention, herein, C1-C10 cycloalkyl is C1-C8 cycloalkyl, C1-C7 cycloalkyl or C1-C6 cycloalkyl.
The term of the present invention, “cycloalkenyl” means a cyclic hydrocarbon group having at least one double bond, and for example, includes cyclopentene, cyclohexene and cyclohexadiene. C3-10 cycloalkenyl means a cycloalkenyl having 3-10 carbon atoms which form a ring structure, and when C3-10 cycloalkenyl is substituted, the number of carbon atoms of the substituent is not comprised.
According to one embodiment of the present invention, C2-10 cycloalkenyl is C2-8 cycloalkenyl, C2-6 cycloalkenyl, C2-5 cycloalkenyl, C2-4 cycloalkenyl or C2-3 cycloalkenyl.
According to one embodiment of the present invention, the R2 is independently of each other hydrogen, C1-10 alkyl or C2-10 alkenyl. According to one specific example, at least two parts or at least three parts of the R2 may be C1-10 alkyl or C2-10 alkenyl. According to one specific example, the cyclosiloxane may have n+1 or n+2 of C1-10 alkyl or C2-10 alkenyl at the R2 position.
According to one embodiment of the present invention, the n is an integer of 1-7, an integer of 1-6, an integer of 1-5, an integer of 1-4 or an integer of 1-3.
According to one embodiment of the present invention, the cyclosiloxane compound is selected from the group consisting of 2,4, 6,8-tetra(C2-10)alkenyl -2,4,6, 8-tetra(C1-10)alkyl cy cl otetrasiloxane, 1,3,5-tri(C1-10)alkyl-1,3,5-tri(C2-10)alkenylcyclotrisiloxane, 1,3, 5,7-tetra(C1-10)alkyl-1,3,5, 7-tetra(C2-10)alkenyl cy cl ° tetra siloxane, 1,3,5,7, 9-penta(C1-10)alkyl-1,3,5, 7,9-penta(C2-10)alkenylcyclopentasiloxane, 1,3,5-tri(C1-10)alkyl-1,3,5-tri(C2-10)alkenylcyclotrisiloxane, 1,3, 5,7-tetra(C1-10)alkyl-1,3,5, 7-tetra(C2-10)alkenyl cy cl ° tetra siloxane, 1,3,5,7, 9-penta(C1-10)alkyl-1,3,5, 7,9-penta(C2-10)alkenylcyclopentasiloxane, 1,3,5-tri(C1-10)alkyl-1,3,5-tri(C2-10)alkenylcyclotrisiloxane, 1,3, 5,7-tetra(C1-10)alkyl-1,3,5, 7-tetra(C2-10)alkenyl cy cl ° tetra siloxane, 1,3,5,7, 9-penta(C1-10)alkyl-1,3,5, 7,9-penta(C2-10)alkenylcyclopentasiloxane, hexa(C2-10)alkenylcyclotrisiloxane, octa(C2-10)alkenylcyclotetrasiloxane, deca(C2-10)alkenylcyclopentasiloxane, 2,4,6, 8-tetravinyl-2,4, 6,8,-tetramethylcyclotetrasiloxane and combinations thereof.
According to one specific example, the cyclosiloxane compound is selected from the group consisting of 1,3,5 -trivinyl-1,3,5 -trim ethyl ecy cl otri siloxane, 2,4, 6,8-tetramethyl-2,4, 6,8-tetravi nyl cy cl otetrasiloxane (V4D4), 2,4, 6,8, 10-p entamethyl-2,4, 6,8, 10-p entavinyl cy cl op entasil oxane, 2,4,6,8, 10,12-hexamethyl-2,4,6, 8,10,12-hexavinyl-cyclohexasiloxane, octa(vinylsilasesquioxane), 2,2,4,4, 6,6, 8,8, 10,10, 12,12-dodecamethylcyclohexasiloxane, 2,4,6,8-tetra(C2-4)alkenyl -2,4,6, 8-tetra(C 1-6)alkyl cy clotetrasiloxane (as one example, 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane), 1,3,5-tri(C1-6)alkyl-1,3,5-tri(C2-4)alkenylcyclotrisiloxane (as one example, 1,3,5-triisopropyl-1,3,5-trivinylcyclotrisiloxane), 1,3,5,7-tetra(C1-6)alkyl-1,3,5,7-tetra(C2-4)alkenylcyclotetrasiloxane (as one example, 1,3,5,7-tetraisopropyl-1,3,5,7-tetravinylcyclotetrasiloxane), 1,3,5,7,9-penta(C1-6)alkyl-1,3,5,7,9-penta(C2-4)alkenylcyclopentasiloxane (as one example, 1,3,5,7,9-p entai sopropyl-1,3, 5,7,9-pentavinyl cy clop entasil oxane), 1,3,5-tri(C1-6)alkyl-1,3,5-tri(C2-4)alkenylcyclotrisiloxane (as one example, 1,3,5-tri-sec-butyl-1,3,5-trivinylcyclotrisiloxane), 1,3,5,7-tetra(C1-6)alkyl-1,3,5,7-tetra(C2-4)alkenylcyclotetrasiloxane (as one example, 1,3, 5,7-tetra-se c-butyl -1,3,5, 7-tetravinyl cy cl otetrasiloxane), 1,3,5,7,9-penta(C1-6)alkyl-1,3,5,7,9-penta(C2-4)alkenylcyclopentasiloxane (as one example, 1,3,5,7,9-p enta-se c-butyl-1,3,5,7, 9-p entavinyl cy cl op entasiloxane), 1,3,5-tri(C1-6)alkyl-1,3,5-tri(C2-4)alkenylcyclotrisiloxane (as one example, 1,3,5-triethyl-1,3,5-trivinylcyclotrisiloxane), 1,3,5,7-tetra(C1-6)alkyl-1,3,5,7-tetra(C2-4)alkenylcyclotetrasiloxane (as one example, 1,3, 5,7-tetraethyl -1,3,5 ,7-tetravi nylcyclotetrasiloxane), 1,3,5,7,9-penta(C1-6)alkyl-1,3,5,7,9-penta(C2-4)alkenylcyclopentasiloxane (as one example, 1,3,5,7,9-p entaethyl-1,3,5,7, 9-p entavinyl cy cl op entasiloxane), hexa(C2-4)alkenylcyclotrisiloxane (as one example, hexavinylcyclotrisiloxane), octa(C2-4)alkenylcyclotetrasiloxane (as one example, octavinylcyclotetrasiloxane), deca(C2-4)alkenylcyclopentasiloxane (as one example, decavinylcyclopentasiloxane) and combinations thereof.
The term of the present invention, “cell culture substrate comprising a siloxane compound” may mean that a polymer formed by siloxane is a part of a cell culture substrate (for example, cell culture substrate of which surface is coated with the polymer), and also may mean that the solid polymer formed by siloxane itself may be used as a cell culture substrate, but not limited thereto.
It is sufficient that the cell culture substrate provides any space capable of culturing a cell, and its shape is not limited. For example, the cell culture substrate may be a dish (culture dish), a chalet or plate (for example, 6-well, 24-well, 48-well, 96-well, 384-well or 9600-well microtiter plate, microplate, dip-well plate, etc.), a flask, a chamber slide, a tube, a cell factory, a roller bottle, a spinner flask, hollow fibers, a microcarrier, beads, and the like, but not limited thereto, and any material having support properties can be used without limitation as the cell culture substrate, and for example, plastics (for example, polystyrene, polyethylene, polypropylene, etc.), metals, silicon and glass, and the like may be used as the cell culture substrate.
In addition, the polymer formed by the siloxane compound is used as a meaning including all of (1) homopolymers formed by polymerization of homogeneous siloxane compounds, (2) copolymers formed by polymerization of heterogeneous siloxane compounds, and (3) copolymers formed by polymerization of homogeneous or heterogeneous siloxane compounds with other monomer compounds. Herein, the copolymer may be random copolymers, block copolymers, alternating copolymers or graft copolymers, but not limited thereto.
Therefore, according to one embodiment of the present invention, the polymer formed by the siloxane compound is a homogeneous polymer formed by polymerization of homogeneous siloxane compounds, and for example, may be a homogeneous polymer formed by polymerization of homogeneous linear siloxane compounds, or a homogeneous polymer formed by polymerization of homogeneous cyclosiloxane compounds.
According to another embodiment of the present invention, the polymer formed by the siloxane compound is a copolymer formed by a first monomer that is the siloxane compound and a second monomer that can polymerize therewith, and for example, may be a copolymer formed by a first monomer that is the linear siloxane compound and a second monomer that can polymerized therewith, or a copolymer formed by a first monomer that is the cyclosiloxane compound and a second monomer that can polymerized therewith.
According to one specific example, the second monomer is a siloxane compound different from the first monomer (copolymer formed by heterogeneous siloxane compounds, for example, copolymer formed by heterogeneous linear siloxane compounds, copolymer formed by heterogeneous cyclosiloxane compounds, or copolymer formed by heterogeneous linear siloxane compound and cyclosiloxane compound).
According to another specific example, the second monomer is a compound having a carbon double bond for polymerization with the first monomer. Then, the first monomer may also have a carbon double bond for polymerization with the second monomer. Such a second monomer compound may be, for example, selected from the group consisting of siloxane having a vinyl group (for example, hexavinyldisiloxane, tetramethyldisiloxane, etc.), methacrylate-based monomers, acrylate-based monomers, aromatic vinyl-based monomers (for example, divinylbenzene, vinylbenzoate, styrene, etc.), acrylamide-based monomers (for example, N-isopropylacrylamide, N,N-dimethylacrylamide, etc.), maleic anhydride, silazane or cyclosilazane having a vinyl group (for example, 2,4,6-trimethyl-2,4,6-trivinylcyclosilazane, etc.), C3-10 cycloalkane having a vinyl group (for example, 1,2,4-trivinylcyclohexane, etc.), vinylpyrrolidone, 2-(methacryloyloxy)ethylacetoacetate, 1-3 (-aminopropyl)imidazole, vinylimidazole, vinylpyridine, silane having a vinyl group (for example, allyltrichlorosilane, acryloxymethyltrimethoxysilane, etc.) and combinations thereof.
According to other specific example, the second monomer may be at least one selected from the group consisting of 1,3, 5-trivinyl-1,3,5-trim ethyl cy cl otri siloxane, 2,4,6, 8-tetram ethyl-2,4, 6, 8-tetravinylcyclotetrasiloxane (V4D4), 2,4, 6,8, 10-p entamethyl-2,4, 6,8, 10-p entavinyl cy cl op entasil oxane, 2,4,6,8, 10,12-hexamethyl-2,4,6, 8,10,12-hexavinyl-cyclohexasiloxane, octa(vinylsilasesquioxane), and 2,2,4,4, 6,6, 8,8, 10,10, 12,12-dodecamethylcyclohexasiloxane.
The methacrylate-based monomer includes, for example, methacrylate, methacrylic acid, glycidyl methacryl ate, p erfluoromethacryl ate, benzylmethacrylate, 2-(dim ethyl amino)ethylm ethacryl ate, p erfurilm ethacryl ate, 3,3,4,4,5,5, 6,6, 7,7, 8,8, 9,9, 10,10, 10-heptadecaflourodecylmethacrylate, hexylmethacrylate, methacrylic anhydride, p entafl ouropheny lm ethacryl ate, prop argylmethacryl ate, tetrahy drop erp erillm ethacryl ate, butylmethacrylate, methacryl oylchl ori de and di(ethyleneglycol)methylestermethacrylate, and the like.
The acrylate-based monomer includes, for example, acrylate, 2-(dimehtylamino)ethyl acrylate, ethyl eneglycolacryl ate, 1H, 1H,7H-dodecafluoroheptylacryl ate, 1H,1H,7H-dodecafluoroheptylacryl ate, isobornyl acrylate, 1H,1H,2H,2H-perfluorodecylacrylate, tetrahy drop erfurilacryl ate, p oly (ethyl enegly col)di acryl ate, 1H,1H,7H-dodecafluoroheptylacryl ate and propargylacrylate, and the like.
The copolymer of the present invention may further comprise a monomer other than monomers mentioned herein as a comonomer.
According to one embodiment of the present invention, the copolymer contains at least 50% or more of the siloxane compound. According to one specific example, the copolymer contains at least 60% or more, 70% or more, 80% or more or 90% or more of the siloxane compound. This content is based on the flow rate (unit: sccm), and 90% means the content of the siloxane compound contained in the copolymer formed by flowing (dropping) each monomer at a flow rate of 9:1 (siloxane compound: other monomer), and 80%, 70% and 60% mean the content of the siloxane compound comprised in the copolymer formed by flowing at a flow rate of 8:1, 7:1 and 6:1.
In addition, the cell culture substrate comprising the polymer may be a cell culture substrate comprising a polymer having various thicknesses. The thickness of the polymer may be, for example, about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 60, 70, 80, 90, 100, 200, 300 nm or more, or about 10,000, 5,000, 1,000, 900, 800, 700, 600, 500, 400, 300 nm or less, or about 10 to 300 nm, 10 to 500 nm, 10 to 1000 nm, 50 to 300 nm, 50 to 500 nm, 50-1000 nm, but not limited thereto.
The cell culture substrate comprising a siloxane polymer according to one embodiment of the present invention may have a water contact angle of 160° or more, 150° or more, 140° or more, 130° or more, 120° or more, 110° or more, 100° or more, 90° or more, 80° or more, 70° or more, 60° or more, 50° or more, 40° or more, 30° or more, 20° or more, or 10° or more.
In the method for preparing a cancer stem cell from a cancer cell, comprising culturing a cancer cell using a medium for cell culture containing albumin, the cancer stem cell may be in a spheroid form. The method may be characterized by not comprising any other compound known for additional gene manipulation or stem cell proliferation, or known to differentiate a stem cell from an adult cell. The medium for cell culture may not comprise other growth factors except for albumin.
The term, “spheroid” means a cell aggregate forming a three-dimensional sphere form by gathering 1000 or more of single cells, and as it can more accurately copy structural and physical properties of the three-dimensional tissue surrounding cells in a human body, it is usefully used in treatment and research fields, and on purpose of the present invention, the spheroid is characterized by a cancer stem cell spheroid.
In addition, the term of the present invention, “cancer stem cell (or tumor initiating cell)” means a cell having an ability to produce tumor, and the cancer stem cell has similar characteristics to normal stem cells. The cancer stem cell causes tumor through self-regeneration and differentiation that are characteristics of the stem cell in various cell types, and therefore it has a cancer-formation ability. It becomes a reason for recurrence and metastasis by causing new tumor distinguished from other groups in tumor by the cancer-formation ability. In addition, as another characteristic of the cancer stem cell, it has drug resistance, and therefore it has resistance to chemical therapies such as anticancer agent usage, and the like, and thus only common cancer cells are removed and cancer stem cells remain without dying, and the cancer may recur again. Thus, to completely cure cancer, it is important to study the cancer stem cell.
Furthermore, to confirm the cancer stem cell, a cancer stem cell marker may be used. The cancer stem cell marker may be CD47, BMI-1, CD24, CXCR4, DLD4, GLI-1, GLI-2, PTEN, CD166, ABCG2, CD171, CD34, CD96, TIM-3, CD38, STRO-1 and CD19, and specifically, it may be CD44, CD133, ALDH1A1, ALDH1A2, EpCAM, CD90 and LGRS, but not limited thereto.
The method of preparing and kit for preparing cancer stem cell spheroids of the present invention have an advantage capable of preparing a cancer stem cell more simply and rapidly, since artificial gene manipulation is not required for preparing a spheroid.
In addition, it has been confirmed that a cancer stem cell (CSC) marker gene prepared by the method and kit is expressed (Example 6), and has a drug resistance property by drug discharging, and has a cancer-formation ability in vivo (Example 12), and therefore the cancer stem cell spheroid prepared by the method and kit of the present invention may be used for studying cancer stem cells and screening its therapeutic agent by having properties of the caner stem cell.
The cancer stem cell spheroid of the present invention may be cultured in a three-dimensional, stereoscopic culture form, and may be a cancer stem cell spheroid which has a characteristic of drug resistance or is cancer cell-derived patient-specific, but not limited thereto.
The term of the present invention, “albumin” consists of basic substances of cells with globulin, and it is comprised in the culture medium of a cancer cell plated in the cell culture substrate of the present invention, and substances capable of forming cancer stem cell spheroids from a cancer cell are included without limitation. The albumin of the present invention may be selected from the group consisting of serum albumin, ovalbumin, lactalbumin and combinations thereof, but not limited thereto. As the example, a commercially available serum replacement (SR) is also included, but not limited thereto. Most of cells require serum to proliferate, and artificial serum or serum replacement which can perform an equal or similar function to natural serum may be used. The artificial serum or serum replacement may be used as a substitute for natural serum in cell culture, and it commonly comprises albumin. The albumin of the present invention may be added as a single component of albumin, or be provided as a formulation comprised in a serum replacement, a formulation prepared by further adding albumin to a serum replacement, or a formulation prepared by further adding albumin to FBS, and more preferably, it may be provided as a formulation in which albumin is further added to a serum replacement, but not limited thereto. In addition, the serum albumin may be selected from the group consisting of bovine serum albumin, human serum albumin and combinations thereof depending on its origin, but not limited thereto. Herein, it has been confirmed that the spheroid prepared using bovine serum albumin expresses a cancer stem cell-related marker (Example 6), and therefore it can be seen that albumin can induce a cancer stem cell.
The albumin concentration may be comprised in a medium at a concentration of 0.1 mg/ml to 500 mg/ml. Specifically, the albumin concentration may be comprised in a medium ata concentration of about 0.1, 0.2, 0.5, 0.6, 1, 1.1, 2, 3, 4, 5, 6, 11, 16, 21, 26, 31, 36, 41, 46, 51, 56, 61, 66, 71, 76, 81, 86, 91, 96, 100, 101, 106, 111, 116, 121, 126, 131, 136, 141, 146 mg/ml or more, or about 500, 450, 400, 350, 300, 250, 200, 199, 195, 190, 175, 170, 150, 149, 144, 139, 134, 129, 124, 119, 114, 109, 104, 99, 94, 89, 84, 79, 74, 69, 64, 59, 54, 49, 44, 39, 34, 29, 24, 19, 14, 9, 4, 1.4, 0.9, 0.4 mg/ml or less, more specifically, about 0.1 mg/ml to about 500 mg/ml, about 0.5 mg/ml to about 500 mg/ml, about lmg/ml to about 500 mg/ml, about 5 mg/ml to about 500 mg/ml, about 10 mg/ml to about 500 mg/ml, about 20 mg/ml to about 500 mg/ml, about 40 mg/ml to about 500 mg/ml, about 0.1 mg/ml to about 400 mg/ml, about 0.5 mg/ml to about 400 mg/ml, about lmg/ml to about 400 mg/ml, about 5 mg/ml to about 400 mg/ml, about 10 mg/ml to about 400 mg/ml, about 20 mg/ml to about 400 mg/ml, about 40 mg/ml to about 400 mg/ml, about 0.1 mg/ml to about 300 mg/ml, about 0.5 mg/ml to about 300 mg/ml, about lmg/ml to about 300 mg/ml, about 5 mg/ml to about 300 mg/ml, about 10 mg/ml to about 300 mg/ml, about 20 mg/ml to about 300 mg/ml, about 40 mg/ml to about 300 mg/ml, about 0.1 mg/ml to about 200 mg/ml, about 0.5 mg/ml to about 200 mg/ml, about 1 mg/ml to about 200 mg/ml, about 5 mg/ml to about 200 mg/ml, about 10 mg/ml to about 200 mg/ml, about 20 mg/ml to about 200 mg/ml, about 40 mg/ml to about 200 mg/ml, about 0.1 mg/ml to about 150 mg/ml, about 0.5 mg/ml to about 150 mg/ml, about 1 mg/ml to about 150 mg/ml, about 5 mg/ml to about 150 mg/ml, about 10 mg/ml to about 150 mg/ml, about 20 mg/ml to about 150 mg/ml, about 40 mg/ml to about 150 mg/ml, about 0.1 mg/ml to about 100 mg/ml, about 0.5 mg/ml to about 100 mg/ml, about 1 mg/ml to about 100 mg/ml, about 5 mg/ml to about 100 mg/ml, about 10 mg/ml to about 100 mg/ml, about 20 mg/ml to about 100 mg/ml, about 40 mg/ml to about 100 mg/ml, about 0.1 mg/ml to about 80 mg/ml, about 0.5 mg/ml to about 80 mg/ml, about 1 mg/ml to about 80 mg/ml, about 5 mg/ml to about 80 mg/ml, about 10 mg/ml to about 80 mg/ml, about 20 mg/ml to about 80 mg/ml, about 40 mg/ml to about 80 mg/ml, about 0.1 mg/ml to about 70 mg/ml, about 0.5 mg/ml to about 70 mg/ml, about 1 mg/ml to about 70 mg/ml, about 5 mg/ml to about 70 mg/ml, about 10 mg/ml to about 70 mg/ml, about 20 mg/ml to about 70 mg/ml, about 40 mg/ml to about 70 mg/ml, about 0.1 mg/ml to about 60 mg/ml, about 0.5 mg/ml to about 60 mg/ml, about 1 mg/ml to about 60 mg/ml, about 5 mg/ml to about 60 mg/ml, about 10 mg/ml to about 60 mg/ml, about 20 mg/ml to about 60 mg/ml, about 40 mg/ml to about 60 mg/ml, about 0.1 mg/ml to about 50 mg/ml, about 0.5 mg/ml to about 50 mg/ml, about 1 mg/ml to about 50 mg/ml, about 5 mg/ml to about 50 mg/ml, about 10 mg/ml to about 50 mg/ml, about 20 mg/ml to about 50 mg/ml, about 40 mg/ml to about 50 mg/ml, about 0.1 mg/ml to about 40 mg/ml, about 0.5 mg/ml to about 40 mg/ml, about 1 mg/ml to about 40 mg/ml, about 5 mg/ml to about 40 mg/ml, about 10 mg/ml to about 40 mg/ml, about 20 mg/ml to about 40 mg/ml, or about 40 mg/ml, and may be comprised in a medium at a concentration of albumin comprised in a serum replacement, but not limited thereto. More preferably, the albumin concentration may be comprised in a medium at a concentration of 0.1 mg/ml to 400 mg/ml, or 0.1 mg/ml to 200 mg/ml. Further preferably, the albumin concentration may be comprised in a medium at a concentration of 0.1 mg/ml to 400 mg/ml, 0.1 mg/ml to 300 mg/ml, 0.5 mg/ml to 400 mg/ml, 0.5 mg/ml to 200 mg/ml, or 0.5 mg/ml to 100 mg/ml.
Herein, the term, “about” includes all of ±0.5, ±0.4, ±0.3, ±0.2, ±0.1, and the like, and about includes all the numerical values equal or similar to the numerical value behind the term, but not limited thereto.
Herein, the term, “culture” means growing a cell under a suitably controlled environment condition, and the culture process of the present invention may be conducted according to suitable medium and culture conditions known in the art. This culture process may be adjusted and used by those skilled in the art according to the selected cell. Specifically, herein, to prepare cancer stem cell spheroids, it may be cultured in an albumin-containing medium, and as the example, it may be cultured in a serum replacement (SR)-containing medium, but not limited thereto.
Other aspect of the present invention provides cancer stem cell spheroids prepared by the method of preparing. The “cancer stem cell” and “spheroid” are as described above.
Other aspect of the present invention relates to a kit for preparing cancer stem cell spheroids, comprising a cell culture substrate comprising a siloxane polymer and a medium for cell culture comprising albumin. The medium for cell culture may induce a cancer cell into cancer stem cell spheroids, and therefore one example of the present invention relates to a kit for preparing cancer stem cell spheroids, comprising a cell culture substrate comprising a siloxane polymer, and a composition for inducing cancer stem cell spheroids from a cancer cell, and the composition for inducing a cancer stem cell from a cancer cell may comprise a medium for cell culture comprising albumin.
The “cell culture substrate comprising a siloxane polymer”, “albumin”, “cancer stem cell” and “spheroid” are as described above.
The kit of the present invention can prepare a caner stem cell spheroid. The kit may comprise a cell culture substrate and a medium as basic composition, and specifically, the cell culture substrate may be a substrate comprising a polymer formed by a siloxane compound, but any substrate which can prepare or culture cancer stem cell spheroids is included without limitation. In addition, the medium may be specifically an albumin-containing medium or serum replacement-containing medium, but any medium which can prepare or culture cancer stem cell spheroids is included without limitation. In the kit, instructions for the method for preparing cancer stem cell spheroids may be further comprised.
Other aspect of the present invention provides a method for screening a drug for treating cancer cell resistance, comprising (a) preparing cancer stem cell spheroids by the method of preparing; (b) treating a candidate substance for treating cancer cell resistance to the cancer stem cell spheroid of the (a) step; and (c) comparing cancer stem cell spheroids group in which the candidate substance for treating cancer cell resistance of the (b) step is treated and a control group in which the candidate substance for treating cancer cell resistance is not treated. The “cancer stem cell” and “spheroid” are as described above.
The comparing cancer stem cell spheroids group in which the candidate substance for treating cancer cell resistance is treated and a control group in which the candidate substance for treating cancer cell resistance is not treated of the (c) step may comprise measuring and comparting the expression level of cancer stem cell markers, and the measuring the expression level of cancer stem cell markers may use common methods for measuring the expression level used in the art without limitation, and as the example, there is western blot, ELISA, radioimmunoassay, radioimmunodiffusion, Ouchterlony immunodiffusion, Rocket immunoelectrophoresis, immunohistostaining, immunoprecipitation assay, complement fixation assay, FACS or protein chip method, or the like.
The term of the present invention, “candidate substance” is a substance expected to treat cancer or substance expected to improve its prognosis, and specifically, may be a substance capable of treating cancer or improving prognosis by removing a cancer stem cell and inhibiting cancer cell resistance, and any substance expected to directly or indirectly enhancing or improving cancer or a cancer stem cell is included without limitation. The example of the candidate substance includes all predicted therapeutic substances such as compounds, genes or proteins, or the like. The screening method of the present invention may confirm the expression level of cancer stem cell markers before and after administration of the candidate substance, and also, determine the corresponding candidate substance as a predicted therapeutic agent for a cancer stem cell or cancer cell resistance, when the expression level is reduced compared to that before administering the candidate substance.
In addition, the (b) step may further comprise treating with a drug having resistance, but not limited thereto.
The method of producing and kit for producing cancer stem cell spheroids of the present invention can conveniently produce cancer stem cell spheroids, and the cancer stem cell spheroid prepared by the method and kit can be effectively utilized for screening drugs for treating cancer cell resistance.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Hereinafter, the present invention will be described in more detail by referential examples, comparative examples and examples. However, these referential examples, comparative examples and example are intended to exemplarily illustrate the present invention, but the scope of the present invention is not limited to these referential examples, comparative examples and examples.
Female BALB/c nude mice (6 weeks) were obtained from Orient Bio Inc., and were stored in an aseptic condition in the animal laboratory of Korea Advanced Institute of Science and Technology. The mice were randomly assigned in random experimental groups. All operations were performed under isoflurane anesthesia, and for ethical procedures and scientific management, all the animal-related procedures were examined and approved by Korea Advanced Institute of Science and Technology, Institutional Animal Care and Use Committee (KAIST-IACUC) (Approval number: KA2014-21).
In addition, to prepare a human ovarian cancer heterologous model, different series of concentrations (106 to 102 cells) of 2D-cultured control SKOV3 cell or SKOV3-ssiCSC isolated from a spheroid corresponding thereto was mixed with 50% Matrigel (Corning), and then was subcutaneously injected to 6-week female BALB/c nude mice. Tumor formation was monitored for 130 days at maximum, and it was recorded that tumor was formed when the tumor volume reached about 50 mm3. To prepare a human breast cancer heterologous model, different series of concentrations (107 to 102 cells) of 2D control cell or ssiCSC derived from MCF7-Luc cancer cell was subcutaneously injected to 6-week female BALB/c nude mice. 50 μl sesame oil (Sigma) dissolved in β-estradiol 17-valerate (2.5 m; Sigma) was subcutaneously administered to BALB/c nude mice through a neck every 10 days. To prepare a human glioma heterologous model, different series of concentrations (106 to 102 cells) of 2D control U87MG cell, ULA-cultured U87MG spheroid or pV4D4-cultured U87MG-ssiCSC cell was mixed with 50% Matrigel, and was subcutaneously injected to 6-week female BALB/c nude mice. Tumor formation from MCF7-Luc and U87MG was monitored by 90 days, and it was recorded that tumor was formed when the tumor volume reached about 50 mm3.
ssiCSC spheroids prepared from different kinds of cancer cells (SKOV3, MCF-7, Hep3B and SW480) were isolated using trypsin (TrypLE Express, Gibco), and the isolated cells were washed with D-PBS twice. The ssiCSC was plated on a 96-well plate (1×104 cells/well) and was cultured in a cell growth medium at 37° C. for 24 hours. Then, the medium was removed, and a new medium comprising various concentrations of doxorubicin was added to each well and cultured for 24 hours. Next, each well was washed with D-PBS and was replaced with a new cell growth medium of 100 μl, and then WST-1 cell proliferation reagent (Roche) of 10 μl was added and cultured for 4 hours. Then, the absorbance at 450 nm (standard wavelength, 600 nm) was measured using a microplate reader (Molecular Devices).
Liver biopsy samples obtained from BALB/C nude mice inoculated by the 2D control group or SKOV3-ssiCSC cancer cell were fixed with 10% formalin, dehydrated and embedded with paraffin, and cut into samples in a thickness of 5 μm, and placed on a slide. The samples were dewaxed and stained with hematoxylin % eosin (H&E) for histological evaluation with a standard optical microscope (Eclipse 80i, Nickon).
Liver metastasis was confirmed by an immunohistochemical method after embedding tissue with paraffin and fragmentating it (5 μm). The fragmented liver tissue was sterilized with 10 mM sodium citrate buffer (pH 6.0) for antigen recovery, and blocked with PBS containing 5% bovine serum albumin (BSA) and 1% goat serum, and then incubated with a rabbit anti-human TNC primary antibody at a room temperature (RT) for 1 hour (20 m/ml; cat. no. AB19011; Millipore). After incubation, the slide was washed with D-PBS, and incubated with a biotin-attached anti-rabbit secondary antibody (1:200; Vector Laboratories) at a room temperature for 30 minutes, and then incubated with HRP (horseradish peroxidase, 1:500, Vector) at a room temperature for 30 minutes. The immunoreactive protein was visualized using a substrate, 3,3-diaminobenzidine (Vector Laboratories), and then counterstained using hematoxylin.
2D control SKOV3 cells and SKOV3-ssiCSC spheroids were dissolved with RIPA dissolution buffer containing proteinase inhibition cocktail (ThermoFisher Scientific) on ice for 30 minutes. Using Bradford protein analysis kit (Bio-Rad), the protein of the lysates was quantified, and the equivalent amount of protein (50m) was isolated by electrophoresis using Bolt 4-12% Bis-Tris Plus polyacryl amide gel (ThermoFisher Scientific). According to the manufacturer's instructions, the gel was dry blotted on a PVDF (polyvinylidene difluoride) film using iBlot2 transfer system (ThermoFisher Scientific).
The PVDF film was immunoblotted by incubating with a primary rabbit anti-phospho-P-catenin antibody (1:1000, cat. no. 9561; Cell Signaling Technology), a mouse anti-β-catenin antibody (1:1000, cat. no. 13-8400; Invitrogen), and a rabbit anti-GAPDH antibody (1:1000, cat. no. 25778; Santa Cruz Biotechnology), and then using standard procedures, it was incubated suitably with an HRP-bound anti-rabbit IgG secondary antibody (1:5000, cat. no. 31460; Invitrogen) or an anti-mouse IgG (1:5000, cat. no. 31430; Invitrogen) secondary antibody. The protein was visualized using SuperSignal West Pico Chemiluminescent Substrate (ThermoFisher Scientific) and ChemiDoc MP system (Bio-Rad).
Flow cytometry was performed as follows. Specifically, after treating 2D control cancer cells and ssiCSC spheroids corresponding thereto, which were cultured as a single layer (cultured for 8 days) with trypsin, the cells were isolated with buffer [D-PBS containing 1% FBS (fetal bovine serum)], respectively. SKOV3, MCF-7, Hep3B, and SW480 cancer cells were stained with an APC (allophycocyanin)-conjugated anti-CD133 primary antibody (1:100; eBioScience), an FITC-conjugated anti-CD44 primary antibody (1:200; BD Biosciences), an PE (phycoerythrin)-conjugated anti-CD90 primary antibody (1:100, MACS; Miltenyi Biotec), and an FITC-conjugated anti-CD133 primary antibody (1:100; Miltenyi Biotec), and were analyzed using a flow cytometry system (BD Calibur and BD LSR Fortessa).
In addition, for side population assays, 2D control cancer cells and ssiCSCs were isolated using trypsin, and stained with Hoechst 33342 (ThermoFisher Scientific) in DMEM containing 2% FBS and 10 mM HEPES buffer at 37° C. for 90 minutes. Then, the cells were washed with HBSS containing 2% FBS and analyzed using a flow cytometry system (BD LSR Fortessa). The flow cytometry data histogram and plot were analyzed using FlowJo software (Tree Star Inc.).
ssiCSC spheroids were imaged using LumaScope 620 system (Etaluma) allowing live ell imaging in a standard incubator (humidification 5% carbon dioxide, 37° C.). Phase difference images were observed using a 10× object lens every 2.5 minutes for 24 hours.
According to the manufacturer's protocol, mRNA was extracted from SKOV3 spheroids and 2D control SKOV3 cells which were cultured on an pV4D4-coated plate for 8 days, using a magnetic mRNA separation kit (NEB). As described in the manufacturer's protocol, using DNase-treated mRNA and NEXTflex Rapid Directional mRNA-Seq kit (BIOO), libraries were manufactured. Each library was sequenced using a single-end method (50-bp reads) in HiSeq2500 system. The sequenced result was compared with human genome (Hg19 version) using STAR aligner (v.2.4.0) 61.
In addition, to investigate DEG, HOMER software algorithm and DESeq R package were used. Heatmap and MA plot were visualized using pheatmap function and plotMA function of R statistical programming language v.3.3.0 (http://www.r-project.org/), respectively.
SKOV3 spheroids were transferred from ULA plate and pV4D4 plate to a 1.5-ml tube, and incubated in 4% paraformaldehyde solution (Sigma) at a room temperature for 30 minutes to fix the spheroids. The fixed spheroids were incubated in D-PBS (Dulbecco's phosphate-buffered saline) solution containing 0.25%(w/v) Triton X-100 (Sigma) at a room temperature for 10 minutes, and washed with D-PBS, and then for blocking, incubated with D-PBS containing 3% BSA.
To staining the spheroids with laminin, the fixed spheroids were incubated with an anti-human laminin primary rabbit antibody (1:100, cat. no.11575; Abcam) at 4° C. for 12 hours. Then, after washing with D-PBS, obtained spheroids were incubated with a rhodamine red-X-conjugated anti-rabbit secondary antibody (1:500, cat. no. R6394; Invitrogen) at a room temperature for 1 hour, and then incubated with Hoechst 33342 for 10 minutes.
In addition, for TNC staining, SKOV3 2D control group or SKOV3 spheroids were incubated with an anti-human TNC primary rabbit antibody (20 m/ml, cat. no.AB19011; Millipore) at 4° C. for 12 hours. Then, after washing with D-PBS, the cells and spheroids were incubated with an FITC-conjugated anti-rabbit secondary antibody (1:500, cat. no.sc-2012; Santa Cruz) at a room temperature for 1 hour. Then, they were incubated with Hoechst 33342 for 10 minutes.
For β-catenin staining, SKOV3 2D control group and SKOV3-ssiCSCs were incubated with a mouse anti-human β-catenin primary antibody (1:100, cat. no.13-8400; Invitrogen) at a room temperature for 1 hour. Then, after washing with D-PBS, the cells were incubated with a TRITC-conjugated anti-mouse secondary antibody (1:1000, cat. no.ab6786; Abcam) at a room temperature for 1 hour, and then incubated with Hoechst 33342 for 10 minutes. All fluorescent images were visualized using a confocal laser-scanning microscope (LSM 780, Carl Zeiss).
Data were represented by mean ±standard deviation (s.d.). Using unpaired Student's t-test of GraphPad Prism software (La Jolla), statistical analysis was performed. P value<0.05 was considered as statistically significant.
In addition, GSE106848 RNA sequencing data of Gene Expression Omnibus data storage of NCBI were used.
(1) Production of Cell Culture Substrate Comprising Siloxane Polymer
1-1: Production of PTF Cell Culture Substrate or Cover Glass Through iCVD Process
A polymer thin film (PTF) comprising a cyclosiloxane polymer was prepared by the following method.
At first, pV4D4 [poly(2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane) polymer thin film (PTF) was prepared. Specifically, for evaporation of monomers, V4D4 [2,4,6,8-tetravinyl-2,4,6,8-tetramethyl cyclotetrasiloxane] (99%; Gelest) and tert-butyl peroxide (TBPO, 98%; Aldrich) were heated to 70 and 30, respectively. The evaporated V4D4 and TBPO were introduced into iCVD chamber (Daeki Hi-Tech Co. Ltd.) at a flow rate of 1.5 and 1 standard cm3/min (sccm). The substrate temperature was maintained at 40, and the filament temperature was maintained at 200, and the pressure of the iCVD chamber was set to 180mTorr. The deposition rate of pV4D4 film was estimated to be 1.8nm/min. The thickness of the pV4D4 film was monitored at the position using an He-Ne laser (JDS Uniphase) interferometer system.
1-2: Production of Cell Culture Substrate Comprising Various Cyclosiloxane Polymers
To produce cell culture substrates comprising various cyclosiloxane compounds, using 1,3, 5 -trivi nyl -1,3 ,5 -trim ethyl cy cl otri siloxane, 2,4, 6,8-tetram ethyl-2,4, 6,8-tetravinylcyclotetrasiloxane (V4D4), 2,4, 6,8, 10-p entamethyl-2,4, 6,8, 10-pentavinylcyclopentasiloxane, 2,4,6,8, 10,12-hexamethyl-2,4,6, 8,10,12-hexavinyl-cyclohexasiloxane, octa(vinylsilasesquioxane), and 2,2,4,4,6,6,8,8,10, 10,12,12-dodecamethyl cycl ohexasil oxane, copolymer substrates were formed at a ratio of 1:9 with pV4D4, respectively. The chemical structures of the various cyclosiloxane compounds were shown in
1-3: Analysis Method
Fourier-transform infrared spectrums (FT-IR) of the V4D4 monomer and pV4D4 polymer were obtained using 64 mean scans and 0.085 cm -1 optical resolution in a normal absorbance mode using ALPHA FTIR spectrometer (Bruker Optics, USA). Each spectrum was calibrated at baseline and recorded in the 400-4000 cm −1 range.
The chemical composition of the pV4D4 PTF surface was analyzed by X-ray photoelectron spectroscopy (XPS; K-alpha, Thermo VG Scientific Inc.) under the atmospheric pressure of 2.0×10−9 mbar. The XPS spectrum was recorded in the 100-1100 eV range using a monochromatic Al Ka radiation X-ray source with kinetic energy (KE) of 12 kV and 1486.6 eV.
The surface topography in the 45×45 μm region was analyzed by an atomic force microscope (AFM; PSIA XE-100, Park Systems) at a scan rate of 0.5 Hz in a non-contact mode.
The water contact angles for the Si wafer, pV4D4-coated Si wafer, tissue culture substrate and pV4D4-coated substrate were measured using a contact angle analyzer (Phoenix 150; Surface Electro Optics, Inc.) by dropping 10 μl deionized water on the corresponding surface.
(2) Production of Cell Culture Substrate Comprising Linear Siloxane Polymer
1-4: Production of PF Cell Culture Substrate Through Cross-Linking Reaction
A polymer film (PF) comprising a linear siloxane polymer was prepared by the following method.
At first, a PDMS (polydimethylsiloxane) polymer film (PF) was prepared. Specifically, for cross-linking polymerization and curing of a monomer and an oligomer, SILGARD® 184 Silicone Elastomer Base and SILGARD® 184 Silicone Elastomer Curing Agent of SILGARD™ 184 Silicone Elastomer Kit (Dow Corning) was mixed and stirred at various weight ratios (9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 1:1) without limitation to a specific ratio, in addition to 10:1 ratio, according to the manufacturer's instructions and protocols.
All bubbles formed in the reactants were removed under the decompression condition at a room temperature for 20 minutes or more using a vacuum desiccator.
The viscous reactants were aliquoted in 10 ul (96-well), 500 ul (350 or 6-well), and 4 ml (1000), respectively, on general tissue culture plates (TCP) (96-well, 35 ø or 6-well, 1000) with various sizes for cell culture using a direct replacement pipette, and then were spread evenly to apply the entire bottom of the substrate. The substrates were placed in a 60° C. oven and the lid was opened a little, followed by curing for 12 hours or more. Herein, mixing of the aforementioned oligomer and catalyst and cross-linker is not limited to a specific ratio, and may be applied to various cell culture platforms without limitation to the substrates with the aforementioned sizes, and the aforementioned aliquot amount for each substrate is also sufficient as long as it can cover all of the substrate bottom, and the aforementioned curing time is not limited to 12 hours.
1-5: Production of Cell Culture Substrate Comprising Linear Siloxane Polymer at Various Polymerization Reaction Ratios
To produce a cell culture substrate comprising siloxane compounds at various ratios, a polymer substrate was formed using a monomer and an oligomer of dimethylsiloxane and a curing sample at various weight ratios. The chemical structure of the general dimethylsiloxane compound formed and the reaction formula were shown in
1-6: Production of Cell Culture Substrate Comprising Various Siloxane Polymers
To produce a cell culture substrate comprising various siloxane compounds, a copolymer substrate was formed using 2,4, 6,8-tetram ethyl-2,4, 6,8-tetravinyl cy cl otetra siloxane (2,4,6, 8-tetram ethyl-2,4,6, 8-tetravinyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane, V4D4) and 1,1,3,3-tetramethyldisiloxane (TMDS) at the molar ratio of 1:4 as follows.
Specifically, TMDS and toluene and Karstedt platinum catalyst were put in a two-neck reaction flask, and V4D4 was filled in a dropping funnel as much as the ratio corresponding to 0.25 times of TMDS. After raising the temperature by 55° C., V4D4 was slowly dropped in the reaction mixture. After adding V4D4, hydrosilylation reaction was progressed between V4D4 and TMDS, stirring at the temperature of 65° C. under the nitrogen condition for about 2 hours. Toluene was removed by distilling at 100° C. for 1 hour, and it was heated at 120° C. for 2 hours to obtain colorless and transparent products.
The products were aliquoted in 10 μl (96-well) and 500 μl (350 or 6-well), 4 ml (1000), respectively, on general plastic substrates (TCP) (96-well, 350 or 6-well, 1000) with various sizes for cell culture, and then were spread evenly to apply the entire bottom of the substrate. The substrates were placed in a vacuum oven and the curing reaction was progressed under the pressure of 40 MPa and the temperature of 120° C. for 24 hours. The chemical structure of the formed siloxane compound and the reaction formula were shown in
2-1: Preparation of Various Human Cancer Cell Lines
Human ovarian cancer cell lines (SKOV3, OVCAR3), human breast cancer cell lines (MCF-7, T47D, BT-474), human hepatocarcinoma cell lines (Hep3B, HepG2), human glioblastoma cell lines (U87MG, U251), human colorectal cancer cell lines (SW480, HT-29, HCT116, Caco-2), human lung cancer cell lines (A549, NCIH358, NCI-H460) and a human prostate cancer cell line (22RV1), a human cervical cancer cell line (HeLa), a human melanoma cell line (A375), and a human stomach cancer cell line (NCI-N87) were purchased from Korean Cell Line Bank (KCLB). It was confirmed that all cancer cells had no mycoplasma using e-Myco mycoplasma PCR detection kit (iNtRON Biotechnology). Those skilled in the art may clearly know that the contents of the present invention are not limited to specific types such as roots or origins of cell lines.
2-2: Method for Forming Spheroids
Cancer cells (1x106) were inoculated on carious polymer thin film substrates, and cultured appropriately in RPMI-1640 medium, DMEM (Dulbecco's Modified Eagle Medium) medium, or MEM (Minimal Essential Medium) medium, comprising 10%(v/v) serum replacement (SR, Gibco), 1%(v/v) penicillin/streptomycin (P/S, Gibco) and L-glutamine, under the humidified 5% CO2 atmosphere of 37° C.
Specifically, SKOV3, T47D, BT-474, SW480, HT29, 22RV1, A549, NCI-H358, NCI-N87, OVCAR3, NCI-H460, and HCT116 cell lines were cultured in RPMI-1640 medium (Gibco) comprising 10%(v/v) SR, 1% (v/v) P/S, and 25 mM HEPES (Gibco). MCF-7, Hep3B, HeLa, U251, and A375 cell lines were cultured in DMEM comprising 10%(v/v) SR and 1%(v/v) P/S(Gibco). HepG2, U87MG, and Caco-2 cell lines were cultured in MEM comprising 10% (v/v) SR and 1% (v/v) P/S (Gibco). In addition, for optimal growth of spheroids, the medium was replaced ever 2-3 days.
2-3: Confirmation of Specificity of Spheroid Formation of Cyclosiloxane Polymer Thin Films
To introduce various surface functionality on a cell culture substrate, a library of polymer thin films (PTFs) was constructed on conventional tissue culture plates (TCP) from various monomers using iCVD (initiated chemical vapor deposition) process, and the manufacturing capacity of cancer-forming spheroids of each PTF was confirmed (
As a result, it was confirmed that a very large number of multicellular spheroids were formed within 24 hours only on pV4D4 [poly(2,4,6,8-tetravinyl-2,4,6,8-tetramethyl cyclotetrasiloxane)] PTF prepared by a cyclosiloxane compound polymer. In contrast thereto, SKOV3 grown on other PTFs showed a form of spreading by being attached similarly to cells grown on TCP (
2-4: Confirmation of Specificity of Spheroid Formation of Siloxane Polymer Thin Film
To confirm the specificity of spheroid formation of the siloxane polymer thin film, the human ovarian cancer cell line, SKOV3 was cultured using a siloxane polymer (PDMS) thin film as a polymer thin film (PTF), but it was performed by the substantially same method as Example 2-3. As a culture medium, FBS or SR medium was used.
Specifically, cancer cells (3.3 to 5×104/cm2) were inoculated on the polymer film substrate at various ratios, and were appropriately cultured on RPMI-1640 (Gibco) medium comprising 10% (v/v) serum replacement (SR, Gibco), 1% (v/v) penicillin/streptomycin (P/S, Gibco), 25 mM HEPES (Gibco) and L-glutamine under the humidified 5% CO2 atmosphere of 37° C. In addition, for the optimal growth of the spheroid, the medium was replaced per 2-3 days.
The result was shown in
However, on the PDMS substrate that is the dimethyl siloxane compound, the spheroid form was shown only in the SR medium, and each cancer cell seemed to agglomerate each other and form a colony within 24 hours on the FBS medium, but it did not grow into a spheroid and spread soon, so the spheroid was not well formed. Based on the result, it can be seen that SR has the higher albumin content than FBS and the induction of the spheroid is promoted. Otherwise, it suggests that the spheroid formation is promoted by an unknown substance which is not comprised in FBS but is comprised in SR.
2-5: Spheroid Formation on Siloxane Polymer Substrates at Various Polymerization Reaction Ratios
To confirm whether a spheroid is formed on cell culture substrates comprising dimethylsiloxane compounds at various ratios, the SKOV3 cell was inoculated on the cell culture substrate prepared in Example 1-5 to confirm that the spheroid was formed, in 6, 24, 48 and 72 hours, respectively.
The result was shown in
TCP showed a form of being attached and spreading (
In general, it is known that the intensity and elasticity of the synthesized dimethylsiloxane compound are different depending on the degree of cross-linking polymerization according to the reaction ratio of the dimethylsiloxane oligomer and curing agent, and the more the mixed amount of the cross-linker and the degree of cross-linking are, the intensity and elasticity of the elastic body is increased. Through the result of the corresponding example, it could be seen that a high quality of spheroid was produced with high efficiency within 24 hours, when cancer cells were aliquoted on the PDMS substrate surface showing the extensive intensity and elasticity according to the dimethylsiloxane compounds at various ratios.
2-6: Establishment of Mixing Ratio of Oligomer and Curing Agent Capable of Spheroid-Inducing Surface Formation
Furthermore, to thoroughly confirm the range of the ratio of the dimethylsiloxane compound at which a spheroid is formed in detail, it was confirmed and selected whether the PDMS elastic body surface suitable for cell culture was formed by a curing action, by progressing the reaction in a 60° C. oven for 10 days or more, so that the cross-linking polymerization and curing sufficiently occurred, according to various ratios changing between the elastic body oligomer and curing agent (cross-linker) (1000:1, 500:1, 100:1, 50:1, 1:10, 1:20, 1:50, 1:100, 1:200, 1:500, 1:1000). The result was shown in
As a result, it was not cured and remained in a fluid state at the other ratios (1000:1, 500:1, 1:20, 1:50, 1:100, 1:200, 1:500 and 1:1000) except for 50:1, 100:1 and 1:10 between the oligomer and cross-linker, and in particular, the ratio comprising a high concentration of oligomer (1000:1 and 500:1) showed the high viscosity (
2-7: Confirmation of Spheroid Induction at Established Mixing Ratio of Oligomer and Curing Agent
In 24 hours after cancer cells were inoculated (5×104/cm2) on the substrates in which the curing reaction was progressed within the mixing ratio of the oligomer and curing agent capable of forming the spheroid-inducing surface, the spheroid formation was confirmed.
Specifically, as the result of selecting the cross-linked and cured ratio suitable for cell culture (50:1, 100:1 and 1:10) and aliquoting the SKOV3 cells on each substrate surface, it was confirmed that a significant number of spheroids were formed within 24 hours in all PDMS substrates comprising dimethylsiloxane and the high efficiency and reproducibility were shown (
Accordingly, it was confirmed that the siloxane polymer substrate had the specificity of cancer cell spheroid formation.
Therefore, it could be seen that a functional PF cell culture substrate in which an appropriate PDMS elastic body surface capable of forming cancer stem cell spheroids was composed, when the dimethylsiloxane oligomer and curing agent were mixed at a ratio corresponding to the range of 100:1 to 1:10.
(1) Spheroid Formation in Substrate Comprising Various Cyclosiloxane Compounds
To confirm whether spheroids are formed on a cell culture substrate comprising various cyclosiloxane compounds, SKOV3 cells were inoculated on the cell culture substrate produced in Example 1-2 and in 24 hours, whether spheroids were formed was confirmed.
Specifically, as the result of confirming whether spheroids were formed on the cell culture substrate comprising various cyclosiloxane compounds of
(2) Spheroid Formation on Substrate Comprising Various Linear Siloxane Compounds
To confirm whether a spheroid is formed on a cell culture substrate comprising various dimethylsiloxane compounds, SKOV3 cells were inoculated on the substrate produced in Example 1-6 and in 24 hours, the spheroid formation was confirmed. Specifically, as the result of observing whether a spheroid was formed on the cell culture substrate comprising the siloxane compound of
(1) Cyclosiloxane Polymer Substrate
Whether PTFs comprising a cyclosiloxane compound polymer had spheroid-forming enhancing ability even in other cancer cell lines other than the human ovarian cancer cell line SKOV3 was confirmed.
As a result, multicellular spheroids (−50-300 μm diameter) were formed in most of human cancer cell lines within 24 hours regardless of roots or origins, and showed high efficiency and reproducibility (
(2) Linear Siloxane Polymer Substrate
Whether the PF comprising a dimethylsiloxane compound polymer showed spheroid-formation enhancing ability for other cancer cell lines other than the human ovarian cancer cell line SKOV3 was confirmed.
As a result, a multicellular spheroid (diameter within and without 100 μm) was formed in human ovarian cell lines regardless of roots or origins within 24 hours, and the high efficiency and reproducibility were shown (
To form spheroids by conventional methods, it was performed as follows.
Specifically, Hanging-drop 96-well plate (3D Biomatrix), U-bottom 96-well plate (SBio), and ultra-low-attachment (ULA) 6-well plate (Corning) were used. Cells were inoculated on hanging drop plate at a density of 1×104 cells/50 μl, and inoculated on U-bottom plate at a density of 5×104 cells/2ml, and inoculated on ULA plate at a density of 5×105 cells/2ml. For optimal growth of spheroids, the medium was replaced every 2-3 days.
(1) Cyclosiloxane Polymer Substrate
5-1: Characteristic of Forming Cancer Cell-Derived Spheroids of Cyclosiloxane Compound Polymer Substrate
In the process of spheroid formation of Example 2-3, each cancer cell was attached on pV4D4 surface at first, but immediately multicellular spheroids were formed simultaneously by intercellular interaction. The activated intercellular interaction on the pV4D4 is a phenomenon which is not observed in other spheroid-forming technology, dependent on simple physical or mechanical contact-based binding.
Different from the conventional hydrophilic ULA (ultra-low-attachment) surface, the pV4D4 PTF surface (
In addition, pV4D4 was deposited on TCP with a thickness of 10, 50, 100, 200 and 300 nm using an He-Ne laser (JDS Uniphase) interferometer system to produce pV4D4 PTFs with various thickness, and the correlation of the thickness and spheroid formation ability was confirmed, and the change of thickness of pV4D4 PTFs in the range of 50 to 300 nm did not affect the spheroid formation ability at all (
These results suggest that cell culture substrates comprising a polymer formed by cyclosiloxane compound can form 3D spheroids having a specific property from cancer cells.
5-2: Analysis of Shapes of Cancer Stem Cell Spheroids Prepared in Cyclosiloxane Polymer Substrate
At first, characteristics of cancer cell spheroids prepared by culturing in the pV4D4 PTF for 4 to 8 days were compared with spheroids prepared by conventional spheroid-forming method prepared in Comparative example 1.
As a result, SKOV3 cancer cell formed one big aggregated spheroid by the hanging-drop method and U-bottom method, but formed several small spheroids on the ULA and pV4D4 surface, and the spheroids formed on the pV4D4 were more homogeneous and slightly smaller than the spheroids formed on the ULA (
Based on the result, it is shown that the spheroids prepared by culturing in pV4D4 of the present invention are not cancer cell aggregates such as spheroids prepared using the conventional method, and repeat the ECM-mediated multicellular structure of tumor tissue in vivo. It is shown that the ECM plays a critical role in the development of drug resistance, self-regeneration and cancer-formation ability in the tumor microenvironment.
(2) Linear Siloxane Polymer Substrate
5-3: Cancer Cell-Derived Spheroid Formation Characteristics of Linear Siloxane Compound Polymer Substrate
In the process of spheroid formation of Example 2-5, each cancer cell was attached on the PDMS surface at first, not limited to a specific polymerization ratio, and immediately, formed a multicellular spheroid by intercellular interaction spontaneously. The intercellular interaction activated on the PDMS is a phenomenon which is dependent on simple physical or mechanical contact-based binding and is not observed in other spheroid-forming technologies. Different from the conventional hydrophilic ULA (ultra-low-attachment) surface, the PDMS PF surface is relatively hydrophobic generally known, and has a surface showing similar roughness to conventional TCPs.
In addition, as the result of curing and producing PDMS PF with various thickness and confirming the correlation between the thickness and spheroid-forming ability, the change of the thickness of the PDMS PF in various ranges did not affect the spheroid-forming ability at all. Taken the results together, it can be seen that in case of PDMS, the specific surface functionality (chemical or biological stimulus) present in the PDMS, not a mechanical signal, induces the spheroid formation.
Such results suggest that cell culture substrates comprising a polymer formed by a siloxane compound can form a 3D spheroid having specific properties from a cancer cell.
5-4: Analysis of Form of Cancer Stem Cell Spheroid Prepared In Linear Siloxane Compound Polymer Substrate
The characteristics of the cancer cell spheroid prepared by culturing in PDMS at the day and for 1, 4 to 8 days were compared to the spheroid prepared by the conventional spheroid-forming method prepared in Comparative example 1.
As a result, the SKOV3 cancer cell formed several small spheroids in the ULA and PDMS surfaces, but the spheroid formed in the ULA was not homogeneous and had a large size mostly, and partially formed one large multicellular aggregate form, whereas the spheroid formed in PDMS (10:1) was much more homogeneous and slightly smaller than the ULA-based spheroid (
(1) Preparation of Cancer Stem Cell Spheroids In Cyclosiloxane Polymer Substrate
6-1: Preparation of Cancer Stem Cell Spheroids in Cyclosiloxane Polymer Substrate
To form cancer stem cell spheroids, SKOV3 cells (1×106) were inoculated on a substrate coated by pV4D4, and suitably cultured on RPMI-1640 comprising 10%(v/v) serum replacement (SR, Gibco), 1%(v/v) penicillin/streptomycin (P/S, Gibco) and L-glutamine under the humidified 5% CO2 atmosphere of 37° C. For optimal growth of spheroids, the medium was replaced every 2-3 days, and spheroids were obtained. The albumin concentration of the serum replacement was lmg/ml or more, and was higher than the concentration of the albumin comprised in FBS (fetal bovine serum) serum.
6-2: Confirmation of Cancer Stem Cell Spheroid Formation Through Confirmation of CSC-Related Gene Expression
To confirm whether spheroids prepared in Example 6-1 have properties of cancer stem cells, expression of CSC-related genes was confirmed using qRT-PCR and RT-PCR. As a control group, spheroids formed by the conventional method of Comparative example 1 was used.
Specifically, to perform qRT-PCR, according to the manufacturer's instructions, total RNA was isolated from 2D-cultured control cancer cells and ssiCSC spheroids. The isolated total RNA was mixed with AccuPower RT PreMix (Bioneer) and was under reverse transcription to cDNA using Rotor-Gene Q thermocycler (Qiagen). The qRT-PCR experiment was performed with 50 ng RNA using Rotor-Gene Q thermocycler (Qiagen) and KAPA SYBR FAST Universal qPCR kit (Kapa Biosystems) according to the manufacturer's instructions.
In addition, to analyze the expression level of CD44, CD133, ALDH1A1, ALDH1A2 and EpCAM that are cancer stem cell marker genes using RT-PCR, a 30-cycle program was performed using HyperScript One-step RT-PCR kit (GeneAll Biotechnology Co. Ltd.) according to the manufacturer's instructions. β-actin was used as an internal control.
The sequences of primers for performing qRT-PCR and RT-PCR were shown in the following Table 2.
As a result, it was confirmed that the expression of ALDH1A1 (aldehyde dehydrogenase 1 family member A1) known as a CSC marker was largely increased only in SKOV3 spheroids prepared by culturing in pV4D4, among various spheroid forming methods through quantitative real-time PCR (quantitative real-time PCR polymerase chain reaction; qRT-PCR) analysis (
6-3: Confirmation of Cancer Stem Cell Inducing Function of Albumin
To confirm that the cancer stem cell (CSC) characteristics of spheroids were induced by albumin, the following experiment was performed.
At first, when various kinds of FBSs and serum replacements (SR) were used, to confirm the expression level of CSC marker genes, the following experiment was performed. Specifically, after culturing U87MG plated on the pV4D4 PTF in 3 kinds (Welgene, Hyclone, GIBCO) of FBSs and SRs for 6 days, the expression level of the CSC markers, CD133 and CD44 was confirmed by flow cytometry. As a result, it was confirmed that the expression level of CD133 and CD44 in case that SR was added was excellent than 3 kinds of FBS (
As a result, it was confirmed that spheroids were formed in a BSA-comprising medium, and it was confirmed that the CSC marker, CD133 was expressed (
In addition, when U87MG, SKOV3, and MCF7 were cultured in a serum-free medium (SFM) comprising FBS, SR or 40 mg/ml BSA in TCP and pV4D4 PTF, the expression level of the CSC marker, CD133 was confirmed by flow cytometry, and represented by a chart (
Based on the result, it could be seen that albumin could induce cancer stem cells, and when cultured on the pV4D4 PTF, culturing by comprising albumin at a specific concentration or higher in a serum-free medium (SFM) could induce cancer stem cells efficiently. Therefore, it could be seen that SR promoted cancer stem cell (CSC) induction of the spheroid, due to the higher albumin content than FBS. In addition, it was confirmed that a spheroid having cancer stem cell characteristics of expressing a CSC marker in the medium comprising albumin at a specific concentration was formed, and a cancer cell was induced to a cancer stem cell by albumin at a specific concentration or more.
6-4: Confirmation of Cancer Stem Cell Characteristics of Spheroids Prepared in Substrates Comprising Various Cyclosiloxane Compounds
To confirm whether spheroids prepared in substrates comprising various cyclosiloxane compounds have cancer stem cell characteristics, the expression level of the cancer stem cell marker gene, CD133 was measured, and the result was shown in
Specifically, using pV4D4 and 6 kinds of cyclosiloxane compounds of
In the axis of
Thus, it could be confirmed that cancer stem cell characteristics could be induced even when other cyclosiloxane compounds other than pV4D4 were used.
(2) Preparation of Cancer Stem Cell Spheroid in Linear Siloxane Polymer Substrate
It was confirmed that a spheroid was formed by culturing a cancer cell in a siloxane polymer substrate in Example 2-4, and to confirm that cancer stem cell characteristics are induced when a medium comprising albumin as a culture medium, the following was conducted.
6-5: Preparation of Cancer Stem Cell Spheroid in Linear Siloxane Polymer Substrate
To form cancer stem cell spheroids, SKOV3 cells (3.3-5×104/cm2) were inoculated in a PDMS-coated substrate, and were appropriately cultured in RPMI-1640 medium comprising 10% (v/v) serum replacement (SR, Gibco), 1%(v/v) penicillin/streptomycin (P/S, Gibco), 25 mM HEPES (Gibco) and L-glutamine under the 37° C. humidified 5% CO2 atmosphere. For optimal growth of a spheroid, the medium was replaced per 2-3 days, and a spheroid was obtained. The albumin concentration of the serum replacement was 1 mg/ml or more, and was higher than the concentration of albumin comprised in FBS (fetal bovine serum) serum.
6-6: Confirmation of Cancer Stem Cell Spheroid Formation Through Confirmation of CSC-Related Gene Expression
To confirm whether the spheroid prepared in Example 6-5 has characteristics of cancer stem cells, the expression of a CSC-related gene was confirmed using qRT-PCR.
Specifically, to perform qRT-PCR, according to the manufacturer's instructions, total RNA was isolated from the 2D monolayer-cultured control cancer cell and ssiCSC spheroid. To quantitatively analyze the expression level of CD133, ALDH1A1, DKK1, OCT3/4, SOX2 and NANOG that are cancer stem cell marker genes including a cancer stem cell-specific surface marker and a stem cell self-regenerative gene, for the isolated total RNA, using Rotor-Gene Q thermocycler (Qiagen) and LeGene SB-Green One-Step qRT-PCR kit (LeGene Biosciences), according to the manufacturer's instructions, the qRT-PCR experiment was performed by a 35-40 cycles program with 100 ng RNA. A housekeeping gene, GAPDH was used as an internal control.
The primer sequences for performing the qRT-PCR were shown in the following Table 3.
As a result, it was confirmed that the expression of CD133 (prominin-1, cluster of differentiation 133) and ALDH1A1 (aldehyde dehydrogenase 1 family member A1), known as CSC markers, was significantly increased in the SKOV3 spheroid prepared by culturing in PDMS by quantitative real-time polymerase chain reaction (qRT-PCR) analysis (
7-1: Confirmation of spheroid formation at various albumin concentrations
The medium was composed by adding BSA so that the concentration of albumin was 0, 0.01 mg/ml, 0.1 mg/ml, lmg/ml, 2 mg/ml, 5 mg/ml, and 10 mg/ml to an SFM medium, and by culturing cancer cells in a substrate comprising a cyclosiloxane compound and a TCP substrate, whether spheroids were formed was confirmed.
As a result, as could be seen in
7-2: Confirmation of Cancer Stem Cell Markers of Spheroids
The medium was composed by adding BSA so that the concentration of albumin was 0, 0.01 mg/ml, 0.1 mg/ml, lmg/ml, 10 mg/ml, 100 mg/ml, 200 mg/ml, 400 mg/ml to an SFM medium, and by culturing cancer cells in a substrate comprising a cyclosiloxane compound, whether spheroids were formed was confirmed.
As a result, as could be seen in
Taking the results together, it can be seen that one example of polymers formed by cyclosiloxane compounds, the pV4D4 surface provides a specific stimulus which activates and modifies SKOV3 cancer cells and induces formation of spheroids of cancer cells, and albumin induces their cancer stem cell characteristics, thereby forming spheroids comprising a significantly large amount of CSC-like cells. Accordingly, the CSC-like cells were named surface-stimuli-induced cancer stem cells (ssiCSCs).
7-3: Cancer Stem Cell Spheroid Formation in Linear Siloxane Substrate
By culturing a cancer cell in FBS and SR media containing albumin (bovine serum albumin: BSA) at different concentrations on the substrate comprising a dimethylsiloxane compound (10:1) and TCP substrate, whether a spheroid was formed was confirmed (
As a result, as could be seen in
Then, by composing an FBS medium, and an SR medium in which bovine serum albumin (BSA) at various concentrations (5, 10, 20, 40 mg/ml) was added, 5×105 SKOV3 cells were inoculated on the PDMS PF (10:1) and TCP and cultured for 48 hours, and in 6, 24 and 48 hours, the spheroid formation and aspect were confirmed.
As a result, it was confirmed that in the TCP substrate, in any case, a spheroid was not formed, and in the PDMS PF substrate, a spheroid was formed in the SR medium comprising a high concentration of BSA rather than the FBS (
This means that in case of the linear siloxane substrate, there are cases where a spheroid is not formed when using FBS as a culture medium, different from the cyclosiloxane substrate, and as a spheroid is well formed when using SR as a culture medium, it could be presumed that SR affects the spheroid formation due to its higher albumin content than FBS or an unknown substance comprised in SR affects the spheroid formation. Therefore, it could be confirmed that the spheroid formation was affected by not only the surface functional stimulus of the substrate but also the culture medium, when preparing a spheroid in the linear siloxane substrate.
7-4: Confirmation of Characteristics of Cancer Stem Cell Spheroid Formed in Linear Siloxane Substrate
To confirm the generalization possibility and versatility of the method for preparation of a spheroid using PDMS, ssiCSC spheroids derived from various cell lines such as human breast cancer cell lines (T47D and BT474) and the like were prepared, and CSC-related characteristics were confirmed. For this, the human cancer cell line derived from breast cancer tissue (T47D) was selected. In addition, presumed CSC characteristics for T47D were confirmed using a cancer stem cell marker such as a specific surface marker of the breast cancer cell line, and the like: CD44 (cluster of differentiation 44), CD24 (cluster of differentiation 24) and ALDH1A1. To confirm the expression of CSC marker genes, the corresponding 2D control group cultured on the TCP and the ssiCSC spheroid cultured on the PDMS surface for 8 days were compared and analyzed by qRT-PCR.
As a result, while CD24 of cell-type specific CSC marker genes was reduced in the ssiCSC spheroid, the CD44 expression was significantly upregulated, and the common marker, ALDH1A1 was increased (
To confirm the possibility of generalization of the method of preparing cancer stem cell spheroids, ssiCSC spheroids derived from various cancer cell lines were prepared, and the CSC-related characteristics were confirmed. For this, 4 kinds of human cancer cell lines derived from various tissues were selected: SKOV3, MCF-7 (human breast cancer), Hep3B (human liver cancer) and SW480 (human colorectal cancer). In addition, estimated CSC characteristics for each cell line were confirmed using specific surface markers by each cell line: SKOV331 -ALDH1A1; MCF-7-CD44 (cluster of differentiation 44); Hep3B36-CD90; and SW48037 -LGRS (leucine-rich repeat-containing G-proteincoupled receptor 5). Furthermore, CD133 was used as a general estimated CSC marker for all cell lines. The expression of CSC marker genes was confirmed by confirming ssiCSC spheroids cultured on the pV4D4 surface for 4 days and 8 days by qRT-PCR, and the expression of the corresponding 2D control group cultured with TCP and the CSC marker genes were compared.
As a result, each cell-type specific CSC marker gene was significantly upregulated in each spheroid, and the expression of the common marker, CD133 was increased in all ssiCSC spheroids (
Then, fractions of the CSC-marker-positive cancer cells estimated in spheroids prepared by culturing on the pV4D4 surface for 8 days were quantified by flow cytometry. As a result, it was shown that the expression of cell-type-specific CSC-related surface markers (indicated by gene counts) was increased approximately 10 times in ssiCSC spheroids of SKOV3, Hep3B and SW480, compared to the 2D-cultured control group, and in case of CD44 of MCF-7 cell, it was increased less than 10 times (
Such results suggest that ssiCSC spheroids prepared using pV4D4 have properties similar to CSC.
9-1: Analysis Method
SKOV3 cells were cultured in the pV4D4-coated substrate for 8 days. After confirming SKOV3-spheroid formation, the ssiCSC spheroids were isolated with trypsin (TrypLE Express; Gibco) and the isolated cells were washed with D-PBS twice.
Wound healing assay was conducted by densely culturing SKOV3 cells and SKOV3-ssiCSCs in a 6-well plate in a single layer, and then synchronizing the cells in a 1% FBS-containing medium for 24 hours. Then, “wound” was made by uniformly scratching the cell single layer with a standard 200 μl pipette tip. Dropped cells were removed by washing with D-PBS twice, and then a serum-free medium was added. The movement of the cells to the wound region was observed using a phase difference microscope (LumaScope 620, Etaluma) right after the wound was made (0 h), in 12 hours (12 h) and in 24 hours (24 h) after it was made.
Invasion assay was conducted by culturing SKOV3 cells and SKOV3-ssiCSCs cells in a serum-free medium for 24 hours at first, and then culturing in Transwell chamber (Corning). Cells (1×105 cells/well) were plated in the upper chamber of the transparent PET film (8.0 μm pore size) coated with Matrigel (200 m/ml; Corning), and allowed to penetrate the lower chamber filled with a medium comprising 10% FBS. The cells were cultured for 24 hours and fixed with 4% formaldehyde (Sigma). Cells which did not penetrate on the upper chamber of the film were removed using a cotton swab. Moving cells on the lower surface of the film were stained with Hoechst 33342 (ThermoFisher Scientific), and the nuclei of penetrated cells were counted using a fluorescence microscope (Eclipse 80i, Nikon). Penetration was calculated by the mean cell number per 5 fields of each film.
For spheroid formation assay, SKOV3 cells and SKOV3-ssiCSCs were cultured in DMEM/F12 (1:1, Gibco) comprising B27 (Invitrogen), 20ng/ml EGF (epidermal growth factor, Gibco), 10 ng/ml LIF (leukemia inhibitory factor, Invitrogen) and 20ng/ml bFGF (basic fibroblast growth factor, Invitrogen). The formation of spheroids was observed by images in 1 hour and 24 hours using a phase difference microscope (LumaScope 620; Etaluma).
9-2: Result
In the wound healing assay, it was confirmed that cancer cells isolated from SKOV3 spheroids prepared by culturing in pV4D4 for 8 days migrated faster than 2D-cultured control cells and filled the gap (
By culturing cancer cells in conventional TCPs, which is isolated from SKOV3 cancer stem cell spheroids prepared by culturing in pV4D4 for 8 days to single cells, “spheroid formation ability” was evaluated. The drawing confirming formation of spheroids by the SKOV3-ssiCSCs and U87MG-ssiCSCs was shown in
As can be seen in
One of other important characteristics of CSC is having immanent or acquired drug resistance for chemotherapeutic agents due to the ability of pushing drugs out. Regarding this, the drug-release ability of each cancer cell isolated from spheroids prepared by culturing on the pV4D4 surface for 8 days was confirmed through Hoechst-dye-based side-population assay. As a result, it was confirmed that fractions of the drug release-positive cell were significantly increased in the ssiCSC prepared from 4 kinds of cancer cell lines compared to the 2D-cultured control group. Specifically, the drug release-positive fractions were increased 0% to 13.8% in SKOV3 cell, 0.59% to 9.6% in MCF-7 cell, 0.58% to 9.2% in Hep3B cell, and 0.1% to 10% in Hep3B cell (
In addition, the drug resistance of ssiCSC for doxorubicin (DOX) known as an anti-cancer agent was confirmed. Specifically, ssiCSC spheroids prepared by culturing on the pV4D4 surface for 8 days were isolated to single cells, and the cell was cultured on the conventional TCP surface to a 2D single layer, and then DOX at various concentrations was treated for 24 hours. As the result of measuring the cell viability using WST-1 analysis method, ssiCSC had higher resistance even to Dox of 50 μM compared to the 2D control group (
The drug-release ability is known to be mediated by ATP-binding cassette (ABC) protein family. Accordingly, using qRT-PCR, in SKOV3-ssiCSC, the expression of multi-drug resistance (MDR) genes, the ABCB1, ABCB2, ABCBS, ABCC1 and ABCG2 panel was analyzed. It was confirmed that in the 5 all MDR-related genes, compared to the 2D-cultured control group, ssiCSC was highly upregulated. In particular, in case of ABCB1 and ABCBS genes, the level of upregulation was remarkable (
As the result of synthesizing molecular or functional analysis of ssiCSC spheroids of the 4 kinds of type cells, it was confirmed that cancer cells were transformed into CSC-like cells which strongly expressed CSC-related genes and had intensive drug resistance, when exposed to a specific stimulus present on the pV4D4 surface.
The cancer-formation ability of ssiCSC in vivo was confirmed. Specifically, SKOV3-derived ssiCSC spheroids were isolated to single cells, and the cells at a series of different concentrations (10 2 to 106 cells) were mixed with Matrigel and subcutaneously injected to BALB/c nude mice (
aTumor formation and mestasis were monitored up to 120 days.
bAll cells were dissociated into single cells and counted with a hemocytometer before subcutaneous injection.
As a result, it was confirmed that the 2D control group did not form tumor at a cell dose of 10 5 or less (0/5 mouse), and could form tumor at 50% frequency at a cell dose of 10 6 (2/4 mice) (Table 4). In contrast thereto, ssiCSC-derived cells could form tumor at higher frequency than the control group even at a very small dose. Specifically, the tumor-forming frequency was 60% (3/5 mice) in case of 10 5 cell dose, 80% (4/5 mice) in case of 10 4 cell dose, and 20% (1/5 mouse) in case of 10 5 cell dose (Table 4). Considering how difficult to obtain heterologous tumor of human ovarian cells (SKOV3) from athymic nude mice without using severe combined immunodeficiency (SCID) mice in general, it could be confirmed that the cancer-formation ability of SKOV3-ssiCSC in vivo was excellent through the result.
In addition, metastatic nodules which were markedly abnormal were found in the liver of ssiCSC-inoculated mice, whereas the liver of 2D SKOV3 control group-inoculated mice appeared normal (
Then, the cancer-formation ability of ssiCSCs derived from various cancer cell lines was confirmed. As a result, ssiCSCs derived from luciferase-introduced MCF-7 (MCF7-Luc) cell and U87MG human glioblastoma cell had significantly increased cancer-formation ability compared to the 2D-cultured control cell (Tables 5 and 6).
aTumor formation was monitored up to 90 days.
aTumor formation was monitored up to 90 days.
Specifically, the 2D-cultured MCF7-Luc cell did not form tumor even if inoculated at a cell dose of 106 per mouse, but the MCF7-Luc-ssiCSC formed tumor at a high frequency (4/5 mice) even if inoculated at a cell dose of 10 5 per mouse (Table 5). Similar thereto, when U87MG-ssiCSCs were inoculated at a cell dose of 10 4, tumor was formed at 60% frequency (3/5 mice), whereas there was no tumor formed when U87MG spheroids cultured on the ULA surface were inoculated, and this shows that the difference of the cancer-formation ability of spheroids cultured in ULA- and pV4D4- is distinct.
Taking the result together, it can be seen that the pV4D4-based PTF may be used as a platform capable of preparing cancer-forming spheroids and may be used for preparation of various human heterologous tumor models which are difficult to be prepared in athymic nude mice.
To confirm cellular and molecular mechanisms related to stem cell-like characteristics of ssiCSCs, several important signaling pathways related to the cancer-formation ability and stem cell of CSCs like Notch, Hedgehog and Wnt/β-catenin were confirmed.
At first, an experiment to confirm whether the Wnt/β-catenin signaling pathway was activated and the expression of Wnt target genes (n=46) was increased in SKOV3-ssiCSCs was performed. As a result, it was confirmed that the expression of 30 genes of 46 Wnt/β-catenin target genes was increased 1.5 times in SKOV3-ssiCSC, and the expression of the core inhibitory factor of the Wnt signaling pathway, Dickkopf-related protein 1 (DKK1) was significantly reduced (
Then, upstream signals causing significant reduction of DKK1 in ssiCSC spheroids was confirmed. As a result, it was confirmed that TNC related to the liver metastasis (
In addition, ssiCSC obtained from MCF-7, Hep3B and SW480 spheroids showed significant expression of TNC (
Taking the result together, activation of Wnt/β-catenin signaling pathways mediated by TNC-DKK1 shows that cancer cells can be converted into cancer-forming CSC-like phenotypes due to the pV4D4 surface.
Cancer cells were cultured in a medium to which BSA was added so that the albumin concentration in the FBS medium was higher than a certain level, to confirm whether cancer stem cell spheroids were formed.
Specifically, after adding BSA to the FBS medium so that the albumin concentration was 5 mg/ml, 10 mg/ml, SKOV3 cells were cultured on the pV4D4 substrate. As a control group, an FBS medium to which BSA was not added was used.
As a result, as could be seen in
In addition, as the result of measuring the expression level of DKK1 of cancer cells cultured like this and showing it based on Beta-actin (
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2019-0087134 | Jul 2019 | KR | national |
