Patent Application
20130209493
The sequence listing is filed with the application in electronic format only and is incorporated by reference herein. The sequence listing text file “B2442027.txt” was created on Sep. 24, 2010 and is 131,287 bytes in size.
The disclosure relates to methods for the detection and prognosis of cancer. Moreover, the disclosure provides methods for detecting circulating tumor cells (CTCs) that include the identification, detection, and optional enumeration of one or more biomarkers associated with CTCs that can be used in methods relating to a prognosis, diagnosis, or the treatment of cancer in a subject.
Most metazoan cells can be classified as either epithelial or mesenchymal based on morphology, behavior and molecular signatures. Epithelial cells are generally polar in the apico-basal direction, adherent to adjacent cells in the plane perpendicular to the polarity, and non-motile in the polar direction. Mesenchymal cells, in contrast, lack polarity, do not form tight interactions with neighboring cells, and are motile. In adult animals epithelial and mesenchymal cells remain stably in one state or the other; that is, an epithelial cell does not change its properties and become mesenchymal. During development, however, epithelial cells of the early embryo give rise to all three embryonal layers (endoderm, mesoderm and ectoderm), which include mesenchymal cells (Hay, E. D., et al. Am. J. Kidney Dis. 1995, 26, 678-690). Therefore, these early embryonal cells have the ability to transition between epithelial and mesenchymal states, a property sometimes referred to as epithelial plasticity. Embryos have been shown to undergo epithelial-mesenchymal transitions (EMTs) as well as mesenchymal-epithelial transitions (METs) (Acloque, H., et al. J. Clin. Invest. 2009, 119, 1438-1449).
Circulating tumor cells (CTCs) are cells that have detached from a primary tumor and circulate in the bloodstream. CTCs may constitute seeds for subsequent growth of additional tumors (metastasis) in different tissues. Thus, detection of CTCs can provide for diagnosis and/or prognosis for overall survival and therapeutic implications in subjects with cancers such as metastatic prostate and breast cancer. The number of CTCs in any patient sample (e.g., a blood sample) can be very small, which can make detection difficult. Current methods for detecting CTCs are based on the detection of epithelial cell adhesion molecule (EpCAM) expression, which is a biomarker associated with epithelial cells. Such methods can under-detect CTCs under circumstances where cells undergo a decrease or loss of EpCAM expression, such as biologic processes including EMT. Because of the important role CTCs can play in the diagnosis, monitoring, and prognosis of disease in patients having cancer, any shortcoming in the detection technology needs to be addressed by the art.
Accordingly, there is a need for methods and systems for detecting CTCs that do not rely on existing capture technologies, and methods for correlating CTC detection to diagnosis, monitoring, and prognosis of disease in cancer patients.
In an aspect, the disclosure provides a method for detecting a circulating tumor cell (CTC) in a biological sample, the method comprising detecting at least one epithelial mesenchymal transition (EMT) biomarker in the biological sample.
In an aspect, the disclosure provides a kit for detecting a circulating tumor cell (CTC) in a biological sample, the kit comprising an antibody to at least one EMT biomarker and instructions for use.
In an aspect, the disclosure provides a method of predicting responsiveness of a subject having cancer to a course of cancer treatment, the method comprising: determining the level or presence of expression of at least one EMT biomarker to obtain an EMT biomarker profile and/or optionally a gene expression pattern for a CTC; and predicting the responsiveness of the subject to the cancer drug based on the EMT biomarker profile and/or optional gene expression pattern. In some embodiments the method includes: determining the level or presence of expression of at least one EMT biomarker in a sample from the subject to obtain a biomarker profile and optionally a gene expression pattern in a CTC for the subject; identifying the type of cancer from the biomarker profile and/or optional gene expression pattern, and optionally characterizing the stage of the cancer; and predicting responsiveness of the subject to the cancer drug based on any one of the biomarker pattern, the optional gene expression pattern, the type of cancer, or the stage of the cancer. Embodiments of this aspect can include detecting a number of cells captured and enumerated from a blood sample using at least one EMT biomarker applied to a sample from the subject. These cells that express the EMT biomarker are thereby captured using the EMT biomarker and could then be used to obtain a gene expression pattern in CTCs for the subject; to predict responsiveness of the subject to the cancer drug based on the obtained gene expression pattern, and for the detection of other biomarkers in these CTCs to assist in guiding therapy of that subject. These cells could also be used to measure the level of the specified EMT biomarker or other EMT biomarkers.
In an aspect, the disclosure provides a method of assessing the number of CTCs using both the traditional EpCAM based capture methodology and an EMT-marker based capture methodology. This EMT-based capture may replace or complement existing CTC capture technologies. The further capture, enumeration, and characterization of these CTCs using EMT antigen capture may further targeting delivery of a cancer drug in a subject having cancer comprising administering to the subject a cancer drug linked to an antibody specific for at least one EMT biomarker or specific drugs based on a gene expression profile or presence of this EMT biomarker.
In an aspect, the disclosure provides a method of estimating the prognosis of a subject with cancer as well as permitting a further characterization of CTCs that may predict for therapeutic responsiveness, the method comprising: determining the level of or presence of expression of at least one EMT biomarker in a sample from the subject to determine the number of CTCs in the subject and to obtain a gene expression pattern for the subject; and providing a prognosis to the subject based on the gene expression or biomarker profile pattern obtained.
In an aspect, the disclosure provides a method for monitoring progression of cancer in a subject undergoing therapeutic treatment, the method comprising detecting the level of expression or presence of expression of at least one EMT biomarker and the quantification of CTCs captured using this method in blood samples taken from the subject at a first and a second time; and comparing the first and second levels of expression; wherein a detected difference in the level of expression of the at least one EMT biomarker in the first and second samples over time indicates a change in the progression status of the cancer.
In an aspect, the disclosure provides a method for detecting cancer in a subject, the method comprising determining the presence of CTCs that express at least one EMT biomarker in a sample from the subject as compared to a normal or control sample, wherein an increased level of at least one EMT biomarker indicates presence of cancer progression or metastatic spread in the subject.
In an aspect, the disclosure provides a method of treating cancer in a subject comprising administering to the subject a cancer drug linked to an antibody that specifically binds at least one EMT biomarker.
Other aspects and embodiments of the disclosure will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments are described in detail, it is to be understood that the claims are not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the included drawings.
In a general sense, the disclosure provides biomarkers that have been identified to be associated with circulating tumor cells (CTCs). As described herein, one or more biomarkers of epithelial mesenchymal transition (EMT) are detectable on CTCs of patients afflicted with common epithelial malignancies. These transitional cells often display stem cell-like characteristics (sternness) and/or plasticity. Further, the disclosure provides description that metastatic propensity and epithelial phenotypic changes correlate with alternative splicing of the FGFR2 gene. The disclosure also provides that, as illustrated in the non-limiting Examples, transitional cells are found in cancer patients where many CTCs co-expressed biomarkers associated with epithelial and mesenchymal cells.
Thus, as described below EMT biomarker expression can be used to detect and quantify CTCs in a biological sample. Accordingly, methods comprising detection of EMT biomarker expression, or detection of CTCs, or a combination thereof, can be used to assess cancer prognosis, tumor invasiveness, risk of metastasis, or to stage tumors. As one of skill in the art will appreciate, any suitable method for evaluating EMT biomarker expression can be used to evaluate EMT biomarker expression according to the methods described herein including, but not limited to, detection with antibodies, real time RT-PCR, Northern analysis, Western analysis, and flow cytometry.
As described herein the ability for a cell to transition easily between epithelial-like and mesenchymal-like states (phenotypic plasticity) is a relevant determinant of malignant fitness more so than the properties of the end states. While these epithelial transitions are phenotypic, the propensity to transition (plasticity) among carcinoma cells may be determined by genotype. The majority of plastic cells may inhabit transitional intermediate states with properties of both epithelium and mesenchyme, and that these transitional cells may be particularly malignant. Such cells may be detected in: (1) tumors where the cancer cells have mixed histology, which indeed have been observed and have been classified as highly aggressive (e.g., clonal sarcomatous carcinomas of epithelial origin, which exhibit an extremely aggressive behavior, such as sarcomatoid renal cell carcinoma and carcinosarcoma of the prostate); and (2) cancer cells co-expressing epithelial and mesenchymal markers, as described herein.
The disclosure, as illustrated by the non-limiting embodiments in the Examples, provides for identification of cells that possess an intermediate phenotype—expressing epithelial and mesenchymal isoforms of FGFR2, having epithelial-like morphology and gene expression patterns, while also displaying mesenchymal cell-like migration, tumor formation, and metastases. In embodiments, these cells are identified in patients with advanced cancer, metastatic adenocarcinoma, and metastatic breast and prostate carcinomas. In some embodiments, the cells comprise CTCs. In some embodiments the CTCs co-expresses biomarkers including, for example, EpCAM, cytokeratin, and vimentin, which identify cells as both epithelial- and mesenchymal-like. In some embodiments, these CTCs in intermediate phenotypic states are identified by detecting EMT biomarkers and provide a diagnosis and/or prognosis of the state and/or degree of malignancy of a cancer.
In an aspect the disclosure provides a method for detecting CTCs in a biological sample, the method comprising detecting at least one epithelial mesenchymal transition (EMT) biomarker in the biological sample. In some embodiments such as illustrated in the Examples, biomarkers of EMT are present on the CTCs of patients with common epithelial malignancies. In some embodiments methods that include detection and identification of alternative splice variants of the FGFR2 gene are used to correlate to metastatic propensity and epithelial phenotypic in a CTC.
Thus, EMT biomarker expression may be used to detect CTCs. EMT biomarker expression, or detection of CTCs, or a combination thereof, may be used to assess cancer prognosis, tumor invasiveness, risk of metastasis, or to stage tumors. As mentioned above, the methods described herein can include any suitable method for evaluating EMT biomarker expression including, but not limited to, detection with antibodies, real time RT-PCR, Northern analysis, magnetic particles (e.g., microparticles or nanoparticles), Western analysis, and any method or system involving flow cytometry. In some embodiments, the methods and EMT biomarkers can be used in a commercially available system such as a system that has been approved by a regulatory agency (e.g., FDA) including, for example, CellSearch® technology (Veridex LLC). Thus, the methods can incorporate standard protocols that are known in the art. For example, embodiments comprising CellSearch® technology can include detecting the presence of an EMT biomarker, and correlated to quantifying the number of circulating tumor cells (CTCs) a biological sample, (e.g., blood collected from women in need of a new treatment regimen for metastatic breast cancer, or men in need of treatment for mCRPC). Typical protocols can include drawing blood sample sizes of about 15 mL that can be collected at any particular time (suitably when the patient starts the new therapy, and then again at three to four week intervals). The number of CTCs can be correlated with disease response or progression as determined by standard radiology studies (e.g., CT scans) performed every nine to 12 weeks.
In an aspect, the disclosure relates to a method for detecting a circulating tumor cell (CTC) in a biological sample, wherein the method comprises detecting at least one epithelial mesenchymal transition (EMT) biomarker in the biological sample. As noted above, a biological sample can be from any tissue or fluid from an organism. In some embodiments the biological sample is from a bodily fluid or tissue that is part of, or associated with, the lymphatic system or the circulatory system of the organism. In some embodiments the biological sample is a blood sample.
The epithelial mesenchymal transition (EMT) and cellular plasticity biomarkers used in the methods described herein are associated with circulating tumor cells (CTCs). Accordingly, in various embodiments the methods include detecting the presence of one or more EMT biomarker and correlating that detection with the presence of a CTC, optionally quantifying the number of CTCs in the sample. As discussed herein, EMT biomarkers can include any detectable biomolecule that is associated with a transitional cell that exhibits characteristics (e.g., phenotype, or surface antigen or gene expression profiles, etc.) of plasticity, stem-like properties, invasiveness, and/or chemo-resistance of a cell. In some non-limiting embodiments, the EMT biomarker includes any of vimentin, N-cadherin, O-cadherin, E-cadherin, FGFR2 splice variant isoforms (such as, for example FGFR2 that includes or excludes either exon IIIc or exon IIIb), or CD133, or any combination of two or more thereof. In some embodiments, the EMT biomarker can include one or more of vimentin (polypeptide SEQ ID NO: 14 encoded by polynucleotide SEQ ID NO: 13), N-cadherin (polypeptide SEQ ID NO: 2 encoded by polynucleotide SEQ ID NO: 1; polypeptide SEQ ID NO: 16 encoded by polynucleotide SEQ ID NO: 15), O-cadherin (polypeptide SEQ ID NO: 4 encoded by polynucleotide SEQ ID NO: 3; polypeptide SEQ ID NO: 18 encoded by polynucleotide SEQ ID NO: 17), E-cadherin (polypeptide SEQ ID NO: 12 encoded by polynucleotide SEQ ID NO: 11; polypeptide SEQ ID NO: 24 encoded by polynucleotide SEQ ID NO: 23), FGFR2 (polypeptide SEQ ID NO: 8 encoded by polynucleotide SEQ ID NO: 7; polypeptide SEQ ID NO: 10 encoded by polynucleotide SEQ ID NO: 9; polypeptide SEQ ID NO: 22 encoded by polynucleotide SEQ ID NO: 21), and CD133 (polypeptide SEQ ID NO: 6 encoded by polynucleotide SEQ ID NO: 5; polypeptide SEQ ID NO: 20 encoded by polynucleotide SEQ ID NO: 19). In some embodiments, the EMT biomarker can include one or more of N-cadherin, for example human N-cadherin (for example SEQ ID NO: 16, CCDS ID No: CCDS11891.1); O-cadherin, for example human O-cadherin (for example SEQ ID NO: 18, CCDS ID No: CCDS10803.0); E-cadherin, for example human E-cadherin (for example SEQ ID NO: 24, CCDS ID No: CCDS10869.1); CD133, for example human CD133 (for example SEQ ID NO: 20, CCDS ID No: CCDS47029.1); FGFR2, for example human FGFR2 (for example SEQ ID NO: 22, CCDS ID No: CCDS31298.1); and vimentin, for example human vimentin (for example SEQ ID NO: 14, Accession No. BC000163). It will be understood by one of skill in the art that when reference is made to polynucleotides that encode polypeptides in the above embodiments as well as embodiments throughout, the polynucleotide can be disclosed as either an RNA (e.g., mRNA) or a DNA (e.g., cDNA).
The EMT biomarkers can be associated with any organism (ortholog) and in certain embodiments are EMT biomarkers associated with a human. Any portion or the entirety of an EMT biomarker can be used for detecting in the methods described herein such as, for example, an epitope of an EMT biomarker protein that binds to an antibody, or a nucleic acid sequence of an EMT biomarker an expressed or transcribed mRNA molecule that is complementary to a reporter nucleic acid probe or primer. In some embodiments, the methods provide for detecting expression of at least two EMT biomarkers. In certain embodiments, expression of vimentin and E-cadherin are detected. In certain embodiments, expression of N-cadherin and O-cadherin are detected. This measure may be used alone or in combination with another method to detect CTCs. In certain embodiments, the methods described herein may be used as a supplemental method in conjunction with CellSearch® Circulating Tumor Cell Test (noted above). Thus, embodiments provide for a method as part of a dual or complementary detection system that can be used to detect and optionally quantify CTCs in a sample (e.g., comprising the detection of EpCAM and at least one EMT biomarker). The expression of at least one EMT biomarker may be used to isolate CTCs. The expression of at least one EMT biomarker may be used to count or provide a relative number or amount of CTCs, using any known method for correlating detection of a biomarker to a cell, such as a CTC. CTCs may be detected at the time of, prior to, or after metastasis.
Cancers may include, but are not limited to, breast cancer, colon cancer, lung cancer, prostate cancer, testicular cancer, brain cancer, skin cancer, rectal cancer, gastric cancer, esophageal cancer, sarcomas, tracheal cancer, head and neck cancer, pancreatic cancer, liver cancer, ovarian cancer, lymphoid cancer, cervical cancer, vulvar cancer, melanoma, mesothelioma, renal cancer, bladder cancer, thyroid cancer, bone cancers, carcinomas, sarcomas, and soft tissue cancers. Thus, the disclosure is generally applicable to any type of cancer in which expression of an EMT biomarker occurs. In certain embodiments, the cancer is a solid tumor malignancy. In certain embodiments, the cancer is breast, colon, or prostate cancer.
Expression of at least one EMT biomarker may be detected using any suitable method known in the art, including but not limited to, binding with antibodies or fragment thereof, antibodies tethered to or associated with an imaging agent, expression reporter plasmids, flow cytometry, and any suitable array scanner technology. The antibody or fragment thereof may suitably recognize a particular intracellular protein, protein isoform, or protein configuration.
As used herein, an “imaging agent” or “reporter molecule” is any entity which enhances visualization or detection of the cell to which it is delivered. Any type of detectable reporter molecule/imaging agent can be used in the methods disclosed herein for the detection of one or more EMT biomarker. Such detectable molecules are known in the art and include, for example, magnetic beads, fluorophores, radionuclides, nuclear stains (e.g., DAPI). For example, an imaging agent can include a compound that comprises an unstable isotope (i.e., a radionuclide) or a fluorescent moiety, such as Cy-5, Alexa 647, Alexa 555, Alexa 488, fluorescein, rhodamine, and the like. Suitable radionuclides include both alpha- and beta-emitters. In some embodiments, the targeting vehicle is labeled. In other embodiments, suitable radioactive moieties include labeled polynucleotides and polypeptides which can be coupled to the targeting vehicle. In some embodiments, the imaging agent comprises a radionuclide such as, for example, a radionuclide that emits low-energy electrons (e.g., those that emit photons with energies as low as 20 keV). Such nuclides can irradiate the cell to which they are delivered without irradiating surrounding cells or tissues. Non-limiting examples of radionuclides that are can be delivered to cells include 137Cs, 103Pd, 111In, 125I, 211At, 212Bi and 213Bi, among others known in the art. Further imaging agents suitable for delivery to a cell in accordance with some embodiments include paramagnetic species for use in MRI imaging, echogenic entities for use in ultrasound imaging, fluorescent entities for use in fluorescence imaging (including quantum dots), and light-active entities for use in optical imaging. A suitable species for MRI imaging is a gadolinium complex of diethylenetriamine pentacetic acid (DTPA). For positron emission tomography (PET), 18F or 11C may be delivered. Other non-limiting examples of reporter molecules are discussed throughout the disclosure.
In an aspect, the disclosure provides a kit for detecting CTCs in a sample. In embodiments, the kit comprises an antibody to at least one EMT biomarker. The antibody in the kit can be connected to or associated with an imaging agent. In embodiments, the kit can comprise an antibody to at least one EMT biomarker, wherein the antibody is associated a magnetic bead. The magnetic bead may be used for ferromagnetic separation and enrichment of CTCs.
Aspects also relate to methods of predicting responsiveness of a subject to a cancer drug. The methods may comprise determining the level of expression of at least one EMT biomarker in a sample from the subject. The level of expression of at least one EMT biomarker may be used to obtain a gene expression pattern in CTCs for the subject. The methods may further comprise predicting responsiveness of the subject to the cancer drug based on the gene expression pattern obtained. Genome variation in CTCs from the subject may also be determined.
Also provided are methods of providing a cancer prognosis to a subject. The methods may comprise determining the level of expression of at least one EMT biomarker in a sample from the subject. The level of expression of at least one EMT biomarker may be used to determine the number of CTCs in the sample. The CTCs may be captured using at least one EMT biomarker. The level of expression of at least one EMT biomarker may be used to determine a gene expression pattern in the CTCs for the subject. A prognosis may be provided to the subject based on the gene expression pattern obtained.
Also provided are methods for following the progress of cancer in a subject. The methods may comprise determining the level of expression of at least one EMT biomarker in samples from the subject at a first and a second time, and comparing the first and second levels of expression. The level of expression of at least one EMT biomarker in the sample may be determined over time, such as following initiation of a new cancer therapy. The level of expression of at least one EMT biomarker in the sample may be used to determine the number or amount of CTCs. An increase between the first and second levels may indicate progression of the cancer. A decrease between the first and second levels may indicate remission or response of the cancer to the therapy. No difference between the first and second levels may indicate arrest or stability in the progression of the cancer.
Also provided are methods of screening for cancer in a subject. The methods may comprise determining the level of expression of at least one EMT biomarker in a sample from the subject. The level of expression of at least one EMT biomarker may be used to determine the amount or number of CTCs in the subject. The level of expression of at least one EMT biomarker may be compared to a normal or control sample. An increased level of at least one EMT biomarker may indicate presence of cancer in the subject.
Also provided are methods of arresting cell growth or inducing cell death of a cancer cell expressing an EMT biomarker. The methods include contacting the cancer cell with a conjugate capable of mediating intracellular delivery of an agent, such as the antibodies to EMT markers described herein. The agent is capable of arresting or attenuating the growth of the cell or inducing cell death through any mechanism after agent internalization. The cancer cell may be contacted with the conjugate in vitro, in vivo, or ex vivo. These methods may be useful in treating cancer by directly targeting cancer cells expressing an EMT biomarker for delivery of agents capable of decreasing or arresting cell growth or inducing cell death.
The disclosure also provides for targeted therapeutic methods and molecules that comprise an anti-cancer agent linked to a binding agent that targets at least one EMT as described herein. In some embodiments the link between the anti-cancer agent and the binding agent is a covalent bond. In some embodiments the link is formed by strong electrostatic interactions (hydrogen bonds, hydrophilic/hydrophobic interaction, or oppositely charged moieties, and the like). Any anti-cancer agent can be used in such molecules and therapeutic methods, and can be selected by one of skill in the art based on the type of cancer to be treated, the progress/stage of the cancer, potential adverse drug interactions, dosage requirements, administration schedule, and the like.
Plasmids and Cell Culture.
The minigene used (pRIIIc12) was previously described (S. Oltean et al., Proc Natl Acad Sci USA 2006, 103, 14116, incorporated herein by reference in its entirety). All cell lines were cultured in low glucose DMEM (Invitrogen) with 10% FBS and 15 IJg/mL blasticidin. Single cell progenies were isolated from a population of AT3 cells stably transfected with pRIIIc12 minigene by limiting dilution to produce a concentration of 1 cell/10 wells and plated on 96-well plates. Cells were counted using a hemocytometer to obtain an initial concentration of 1×105 cells/mL. Through a series of progressive dilutions a final concentration of 1 cell/mL was obtained and 100 IJI were pipetted in each well of three 96-well plates. All wells were monitored through bright field microscopy, those appearing to contain more than one cell were excluded, and those containing single cells were further cultured into 25 mL flasks. 16 of an expected 27 clones were obtained using this procedure in a first round.
To measure cell population growth rate in vitro, cells were plated at 50,000/well in E-well dishes. Viable cells were counted using Trypan Blue staining at 24, 48, 72, and 96h.
Animals and Tumor Cell Implantation.
Cells were trypsinized, washed, and resuspended in PBS at a final concentration of 3×105 cells/mL, and kept on ice for less than 30 minutes before implantation. Cells (3×105) were injected subcutis in both flanks of Copenhagen 2331 rats (Harlan Labs, Indianapolis, Ind.; 75-90 g, 2 months of age). Animals were continuously monitored for tumor growth. All animal procedures were approved by the Duke University Institutional and Animal Care and Use committee and followed NIH guidelines. Sacrifice curves were compared using a Mantel-Haenszel logrank test. Tumor volume was compared using an unpaired t test. Prism 4.0c for the Macintosh (Graphpad, La Jolla, Calif.) was used for statistical analyses.
Histological Sections and Analysis.
Excised tumors and lungs were washed in PBS at room temperature. Depending on the size of the lungs, they were frozen either together or separately. The tumor sections and the lungs were placed in cryomolds, embedded in optimal-cutting-temperature tissue sectioning medium (Sakura Finetek, Torrance, Calif.), snap-frozen in liquid nitrogen, and stored at 80° C. Slides for fluorescence imaging were prepared as follows: the tissue was incubated for 2-3 h at −20° C. to equilibrate the temperature and then sectioned with a microtome. The sections (15 gm) were placed on glass slides, fixed in 4% (wt/vol) paraformaldehyde for 30 min at room temperature, and rinsed in PBS at room temperature. The slides were mounted with gel/mount media (Biomeda, Foster City, Calif.). The sections were analyzed by using an Olympus (Melville, N.Y.) IX 71 epifluorescence microscope, and images were acquired by using an Olympus DP70 digital camera. Image processing was done with DP Controller software (Olympus). For hematoxylin-eosin staining after fluorescence imaging, the slides were incubated in warm water for 15-20 minutes for the cover slip to come off, slides were dried, and staining was performed according to standard procedure.
RNA Extraction from Tumor Sections.
Sections were fixed in 4% (wt/vol) paraformaldehyde for 5 minutes, rinsed in PBS, and imaged. DsRED+ and DsRED− regions of the sections were marked on the slide. The slide was immersed in warm water for 5 minutes to remove the coverslip and the DsRED+ and DsRED− regions scraped off. RNA isolation was further performed as described before (N. Masuda, T. Ohnishi, S. Kawamoto, M. Monden, K. Okubo, Nucleic Acids Res 1999, 27, 4436, incorporated herein by reference in its entirety). Briefly, samples were treated with proteinase K in digestion buffer containing SDS, and further isolation of RNA was performed using the RNeasy kit (QIAGEN, Valencia, Calif.).
Immunoblots.
Cells were collected from confluent 25 cm2 tissues flasks by scraping, washed in PBS, and lysed in sample buffer. Whole cell lysates were serially diluted in sample buffer, fractionated via 7.5% SDS-PAGE, and transferred to PVDF. Membranes were cut in half. The bottom half was probed with anti-β-actin at 1:1000 or 1:5000 (Santa Cruz Biotechnology, CA, 47778) as an internal loading control, while the top half was probed with anti-CD 133 (Santa Cruz Biotechnology, CA, 30219) at 1:200 or anti-CD44 (Santa Cruz Biotechnology, CA, 7946) at 1:200.
Gene Expression Analysis.
Triplicate cultures of AT3-M and AT3-T cells were grown to −60% confluency. Total RNA was isolated using the RNeasy kit (Qiagen, Valencia, Calif.), and triplicate samples were submitted to the Duke Microarray Facility. Gene expression analysis was performed using the R027K rat spotted arrays 3.0 (Operon, Huntsville, Ala.). Bioinformatical analysis of expression differences between AT3-M and AT3-T cells was done using the GeneSpring GX software version 7.3.1 (Agilent Technologies, Durham, N.C.). The data files (representing signals for 26,986 gene probes in all six data points, three for AT3-M and three for AT3-T) were normalized using the feature: per Spot and per Chip—intensity dependent (Iowess) normalization. The resulting gene list was used to determine the significantly differentially expressed genes between AT3-M and AT3-T using the “Filtering on Volcano plot” feature with the following characteristics: (1) Test type: Parametric test, don't assume variances equal; (2) Multiple testing correction: None; (3) Fold Difference: Twofold or greater and a P-value cutoff of 0.05.
Analysis of Human Circulating Tumor Cells.
Patients eligible for the CTC biomarker protocols included (1) men with progressive CRPC, with metastatic progression by PSA (two consecutive rises over nadir separated by >1 week) or radiologic criteria (RECIST or new bone scan lesions), a PSA age ≧5, age ≧18 years; or (2) women with mBC with disease progression or with initiation of a new systemic therapy, who were >18 years of age, and who were at least 7 days from treatment with an anthracycline-containing regimen. Blood (15 mL) was collected from patients and processed within 48 hours at the Duke University CTC lab using the Cell Search System (Veridex, Raritan, N.J.). Veridex profile kits were used, which isolate EpCAM positive cells without additional staining. The isolated cells were either processed immediately or stored overnight in 4% paraformaldehyde and processed the next day. Immunostaining was done on teflon coated slides. Briefly, cells were pipetted into the wells of the slides and left to settle for ˜30 minutes followed by standard immunostaining procedures with careful aspiration to minimize cell loss. An initial ferromagnetic wash using a benchtop magnet was performed to further isolate CTCs, with resuspension of the cell pellet after magnet release 100 uL PBS. Following 4% PFA fixation and permeabilization with PBT (PBS with 2% Triton) and blocking with 10% goat serum for 30 minutes, triple immunostaining was performed using CD45 antibody (AbCam #33533-50) labeled with Alexa 647, cytokeratin (AbD Serotec #MCA 1907HT) labeled with Alexa 555, and Vimentin (BD Biosciences, San Jose, Calif. #550513) labeled with Alexa 488. Nuclear staining with 4′,6-diamidino-2-phenylindole (DAPI) was then performed. A CTC was defined as an intact cell by microscopic examination, containing an intact nucleus and expressing cytokeratin but lacking CD45 staining, using appropriate controls (see Table 1 for antibodies and controls). Human peripheral blood mononuclear cells (PBMCs), obtained by Ficoll purification of buffy coats from normal donors, were kindly provided by Micah Luftig (Duke University, Durham N.C.) and used as control cells for CD45 expression. Linear regression analysis was performed to compare CTC count (standard Cellsearch method) against the proportion of CTCs that co-express vimentin. Goodness of fit was tested by analysis of variance.
The slides were mounted with gel/mount media (Biomeda, Foster City, Calif.). The slides were analyzed with an Olympus (Melville, N.Y.) IX 71 epifluorescence microscope, and images were acquired using an Olympus DP70 digital camera. Image processing was done with DP controller software (Olympus). All fields were analysed, with each cytokeratin positive nucleated cell that was CD45 negative being counted as a CTC. Positive control cells for each antibody included PC-3 cells for vimentin, peripheral blood mononuclear cells (PBMCs) for CD45, and T47D breast cancer cell lines for cytokeratin. A similar volume of reaction mix without antibody was used for negative controls.
Media exchange experiments. The cells of AT3-T or AT3-M clones were plated at a concentration of 150,000 cells/2 mL of media in 6-well plates and allowed to incubate for 24 h. The conditioned media was then filtered using a 0.22 μm filter, and then immediately allowed to incubate with cells of the other clone, which was plated at the same concentration and had its media aspirated and cells washed with 2 mL of PBS. All cells with media replaced were incubated for 72 h, and phase and epifluorescent microscopy was used to monitor cell phenotypes 24, 48, and 72 h after treatment. Control plates, in which media was conditioned, cells washed with PBS and media added back to the same cells, were also used.
Scratch-Wound Assay.
Cells were plated and left to grow to nearly 100% confluency in 6-well dishes. A wound was simulated by scratching the cells with a sterile 200 IJI pipette tip. The wells were washed twice with PBS and fresh media added. Pictures were taken in the same marked spot at 0, 24, and 48 h. Percent migration was calculated as (width at 0 h−width at 24 or 48 h) 1 width at 0 h×100. Relative migration was compared using two-way analysis of variance via Prism 4.0c for the Macintosh (Graphpad, La Jolla, Calif.).
Matrigel Assay.
Matrigel assay was performed per manufacturer's indications (BO Biosciences). Briefly, after rehydration, 2×105 cells were plated either in the control or in the matrigel-coated inserts and incubated for 22 h. Following incubation, the non-invading cells from the upper-part of the inserts were removed using cotton-tipped swabs. The cells from the lower part of the membrane were stained with hematoxylin-eosin, membranes were removed, placed on a slide and observed under the microscope.
Immunohistochemical (IHC) Analysis of Metastases.
Under the same informed consent protocol as the analysis of human circulating tumor cells described above, men undergoing CTC collection additionally consented to have a radiologic-guided metastatic biopsy for analysis of biomarker expression by IHC. Samples were obtained through core needle biopsies during light sedation, and immediately formalin-fixed and paraffin embedded. For analysis, slides were deparaffinized, rehydrated, and endogenous peroxidase was inactivated for 30 min. in 0.3% H2O2 (hydrogen-peroxide) in methanol. Specific antigen retrieval steps were performed for individual antigens. Three markers were evaluated by IHC: vimentin (M7020, Dako, 1:150; antigen retrieval with pepsin treatment at 37° C. for 15 minutes), cytokeratin cocktail (18-0132, Invitrogen, 1:50 and 349205, BD Biosciences 1:50, antigen retrieval with pepsin treatment at 37° C. for 15 minutes), and CD45 (M0701, Dako, 1:200; antigen retrieval with sodium citrate 10 mM, pH 6.0 at 100° C. for 30 minutes). Primary antibody was incubated for 60 minutes at room temperature. Dako Envision horseradish peroxidase secondary antibody was used for 30 minutes at room temperature and the signal was detected with DAB reagent (Vector kit SK 4100). Slides were counter stained with hematoxylin and eosin and assessed by a trained pathologist for expression using appropriate positive (localized prostate tissue microarray sections) and negative controls (mock antibody) for each marker.
Statistical Analyses.
To determine the significantly differentially expressed genes between AT3-M and AT3-T the GeneSpring GX “Filtering on Volcano plot” feature was used with the following characteristics: (1) Test type: Parametric test, don't assume variances equal; (2) Multiple testing correction: None; (3) Fold Difference: Twofold or greater and a P-value cutoff of 0.05. To compare CTC count (standard Cellsearch® method) against the proportion of CTCs that co-express vimentin, N-cadherin, or CD133, linear regression analysis was performed. Goodness of fit was tested by analysis of variance.
The alternative splicing of FGFR2 transcripts, which produces either FGFR2-IIIb or -IIIc variants in epithelial and mesenchymal cells respectively, is exquisitely regulated (
In an attempt to find post-MET cells in vitro, limiting dilution was used to obtain clones from AT3 cells stably transfected with the pRIIIc12 reporter. A total of 16 clones of a maximum calculated recovery of 27 were obtained, which is ˜60% cloning efficiency. Eleven of these sixteen clones expressed RIIIc12 transcripts (italicized in Table 2), and of these, eight expressed DsRED (Table 2). Some of the clones had an epithelial-like morphology (cells with cobblestone appearance and adherent to each other), while others had a mesenchymal-like morphology (spindle-shaped), as well as clones that displayed a mixed phenotype. It is important to note that given the high cloning efficiency and the high frequency of DsRED+ clones, it is highly unlikely for these epithelial-like clones to come from a very small population within the parental AT3 cells. Rather, the process of subcloning induced a phenotypic transition in a significant number of the AT3 cells.
1See FIG. 1C. A “+” indicates detection of RIIIcl2 transcripts missing exon IIIc, a “−” all RIIIcl2 transcripts include exon IIIc, ND means that no RIIIcl2 transcripts were detected.
2Determined by epifluorescence microscopy (high is defined as fluorescence above background of naive AT3 cells and low undistinguishable from the same cells).
3Discussed further herein and illustrated in FIG. 1C.
All of the clones obtained by limiting dilution were analyzed to determine the splicing status of RIIc12 and endogenous FGFR2 transcripts. We could not detect exon IIIc skipping among pRIIIc12 transcripts or any evidence of exon IIIb inclusion among endogenous FGFR2 transcripts in clones with a mesenchymal-like morphology (
We followed two clones with epithelial morphology, high DsRED levels and co-expression of FGFR2-IIIb and -IIIc transcripts (clone 2 and clone 5 (clone 5 herein AT3-T)) and noted that the phenotypic characteristics described above were stable for over six months. Equally, we followed clone 11 (clone 11 herein AT3-M) and clone 12 for six months, and noted that the mesenchymal morphology, undetectable DsRED expression and exclusive production of FGFR2-IIIc were also stable. We concluded from these observations that AT3 cells were plastic and were coaxed by sub-cloning to populate intermediate phenotypic states, with properties of epithelial and mesenchymal cells.
A media exchange experiment was used to investigate whether or not the splicing of RIIIcI2 transcripts in the DsRED expressing clones was regulated by soluble factors. Media conditioned by DsRED expressing clones (clone 5 in Table 2) was filtered and added to DsRED negative clones (clone 11 in Table 2). DsRED+ cells were observed among DsRED-cells incubated with DsRED+ conditioned media (
The initial characterization of the AT3-T revealed that these transitional cells grew slower and reached a lower confluent density than the AT3-M (
We injected 3×105 GFP-expressing AT3-T or AT3-M cells subcutis in both flanks of Copenhagen white 2331 male rats. All of the animals developed bilateral tumors, indicating that both AT3-M and AT3-T cells were highly tumorogenic in these syngeneic rats. As a humane endpoint, rats were sacrificed when tumor length estimated by palpation reached 1 cm. The in vivo growth curves for the AT3-M and AT3-T tumors were significantly different, as determined by a logrank test (p=0.0020;
Since the implanted AT3-M and AT3-T cells could be tracked by GFP expression, and epithelial character could be interrogated by DsRED expression, the plasticity of the tumors were able to investigated. The overwhelming majority of cells in AT3-M tumors expressed GFP but not DsRED (
Many sections from AT3-T tumors co-expressed GFP and DsRED; however, large areas were observed that expressed GFP but not DsRED in all 64 sections surveyed (
Comparison of AT3-T and AT3-M mobility and invasive potential was performed in culture. Motility was measured in culture by a “wound closure” assay, and no significant motility difference (p=0.59) was found between cell lines 24 and 48 hours after a scratch-wound had been made in the cultures (
In order to assess invasiveness in vivo lungs from the twenty animals harboring AT3-M and AT3-T tumors were examined for presence of metastatic foci. No macroscopic metastatic nodules were observed in any of the lungs, which was likely due to the sacrificing protocol used on the animals when the tumors reached a specified size instead of using survival as the end-point. The GFP expression from the Gint reporter was examined to evaluate the presence of micrometastases by epifluorescence microscopy. To assure a comprehensive evaluation, 7-8 equally spaced sections from each lung were surveyed (total of 150 sections for each clone). The presence of metastatic foci was determined by GFP fluorescence, followed by counter-staining of the sections with hematoxylineosin (
Evaluation of the plasticity of the metastatic foci using the combined output of the GFP and DsRED reporters revealed plastic foci (DsRED+ for AT3-M and DsRED− for AT3-T) in the case of both clones: 3 out of 12 for clone AT3-T and 13 out 16 for clone AT3-M (
Plasticity and Metastatic Behavior of Cancer Cells.
Both the mesenchymal AT3-M and the more epithelial AT3-T cells metastasized efficiently. The drivers of metastasis, however, may be different in these two cells. The gene expression comparison between the AT3-M and AT3-T clones revealed at least one intriguing possibility: microarray analysis showed a 12-fold increase in the expression of junctional adhesion molecule C (JAM-C) in AT3-T compared to AT3-M, and this was confirmed by RT-PCR and immunoblot analysis. JAMs were present in leukocytes and at the tight junctions of epithelial and endothelial cells and have been shown to be involved in transendothelial migration of monocytes. JAM-C is expressed in several cell lines with high metastatic potential and knock-down of this molecule in the HT1080 human fibrosarcoma line significantly decreases its metastatic properties in vivo. Moreover, JAM-C is also present in the gene sets associated with sternness that had significant overlaps with genes that define clone AT3-T. Therefore clone AT3-T, by over-expression of different adhesion molecules may acquire metastatic capabilities. In addition, the overexpression of the downstream Hedgehog pathway effector GLI3 may be significantly upregulated in the more epithelial and stem cell-like AT3-T cells as compared to the more mesenchymal AT3-M cells. Hedgehog signaling has been linked to EMT, sternness, and metastasis/aggressiveness in several tumor types, and thus differential expression or regulation of developmental programs may underly these phenotypical differences across these cell lines. Increased expression of Patched, a Hedghog pathway component, has been linked to prostate tumors during progression to androgen independence and in circulating tumor cells of men with metastatic castration-resistant prostate cancer.
AT3-T cells sometimes formed tight clusters resembling protospheres. While sphere formation is not an exclusive property of stem cells, it has been associated with sternness in many different systems. Given these observations and the high tumorogenicity of AT3-T and AT3-M cells, they were tested for the expression of markers associated with cancer stem-like cells. Also included were the parental AT3 cells and another Dunning tumor cell line, DT cells, which display epithelial markers and are only weakly tumorogenic in Copenhagen white rats. The DT cells expressed very low levels of CD44 and CD133, which are associated with highly malignant cancer stem-like cells (
To further explore these connections between transitions and sternness, global gene expression in AT3-M and AT3-T cells was compared. This analysis showed that 422 genes were differentially expressed (≧2-fold; p-value <0.05) in these two cells (Table 3). Many of the genes that were upregulated in AT3-T relative to AT3-M were preferentially expressed in epithelial cells and vice versa for those preferentially expressed in mesenchymal cells (Table 4). There were exceptions to this, however. Expression of the gene disintegrin-like and metalloprotease was consistent with a mesenchymal phenotype, but this mRNA level was 4-fold higher in AT3-T compared to AT3-M. Integrin β-4, normally associated with epithelial-like cells, was expressed 3-fold lower in AT3-T compared to AT3-M. These observations were consistent with the characterization of AT3-T cells as displaying more epithelial features than AT3-M cells and as populating an intermediate phenotypic state.
Two gene sets were assembled: one composed of gene products upregulated in AT3-T (relative to AT3-M) and the second of those downregulated in AT3-T (relative to AT3-M). The two gene sets were compared for overlap with 5,452 gene sets from the Molecular Signature Database collections (Gene Set Enrichment Analysis (GSEA) http://www.broad.mit.edu/gseaf). Analysis of genes over-expressed in AT3-T relative to AT3-M for overlap with 5,452 gene sets from the Molecular Signature Database collections via Gene Set Enrichment Analysis (GSEA) did not show any significant enrichment of sets associated with EMT or MET. In this regard, both AT3-M and AT3-T resembled the mesenchymal-like, parental AT3 line. Among the 15 most significant overlaps for the genes overexpressed in AT3-T there were three sets of genes activated in hematopoetic stem cells (p=3.24×10−8), neural stem cells (p=3.07×10−7) and embryonal murine stem cells (p=5.14×10−6), (Table 5) while among the 20 most significant overlaps for the genes that are relatively downregulated in AT3-T cells were two gene sets associated with development of mature cell types. Expression of the downstream hedgehog pathway effector GL13 was found to be 3.4-fold overexpressed in AT3-T cells compared to AT3-M cells, indicating that regulation of this developmental/stemness pathway in prostate cancer may be tied to the underlying phenotypic state during EMT/MET, similar to what has been reported in other tumors. These data indicated that AT3-T cells have gene expression profiles similar to stem cells, and, in concordance with the analysis of CD44 and CD133 protein expression, suggested that AT3-T cells exist in a more stem cell-like state than the more mesenchymal AT3-M cells.
Epithelial Plasticity and Stem Cell-Like Behavior.
It is well appreciated that cells induced to undergo EMT activate stem cell pathways. Work presented here shows that AT3 cells that transitioned towards a more epithelial state, i.e. were involved in MET, also activated expression of stem cell-like markers. This finding suggested a broader relationship between plasticity and stem cell-like character or sternness, which was modeled using a Gibbs free energy diagram (
The model also predicts that cells with maximal stem-cell character, which by definition will be highly malignant, should display both epithelial and mesenchymal traits, because they inhabit intermediate states in the epithelialmesenchymal axis. The highly malignant rat adenocarcinoma AT3-T cells are in this type of state. Importantly, in humans with metastatic breast and prostate carcinomas many CTCs also exist in these intermediate states. These cells correlate with disease progression and are believed to be highly aggressive. A population of cells enriched in CTCs expressed RNAs encoding mesenchymal markers; however, the data did not indicate whether or not epithelial and mesenchymal markers were co-expressed in the same cell. Another clinical example of cells in intermediate states is found in sarcomatoid renal cell carcinomas, which have been shown to co-express epithelial markers, such as epithelial membrane antigen, and mesenchymal ones, like vimentin. These tumors, though rare (1-8% of renal tumors) are highly aggressive and difficult to treat. A similar situation may be found in carcinosarcomas of both the prostate and breast, highly aggressive, rare tumors with mixed epithelial and mesenchymal components but of clonal origin. It is not completely clear whether or not single cells in these tumor co-express epithelial and mesenchymal markers and are thus truly in intermediate states.
Finally, the model suggests that as sarcomas undergo MET they will activate stem cell-like pathways and become more aggressive. Indeed, there are many descriptions of sarcomas with mixed epithelial and mesenchymal components in close proximity as seen in some synovial- and osteo-sarcomas. New genetically-defined mouse models of soft tissue sarcoma should shed light on the existence and importance of cells intermediate cell states in progression of these tumors.
The experiments described above indicated that Dunning rat prostate adenocarcinoma cells that inhabit an intermediate phenotypic state are tumorogenic, metastatic, and possess stem cell-like antigens and cellular programs. To investigate whether or not similar transitional cells could play a role in human cancer, cancer cells isolated from blood of men with metastatic castrate resistant progressive prostate cancer (CRPC) or women with progressive metastatic breast cancer (mBC) were examined. Circulating tumor cells (CTCs) represent an ideal source of tissue to investigate evidence of this plasticity in vivo, given that these cells are likely to be in circulation prior to and during metastatic colonization. CTCs have both independent prognostic and predictive significance in multiple epithelial malignancies, including breast and prostate cancer. These cells can be collected, isolated, and analyzed for a variety of biomarkers relevant to cancer biology.
It was tested whether there was a high likelihood of finding transitional cells within a population of CTCs captured by FDA-approved EpCAM (Epithelial Cell Adhesion Molecule)-targeted ferromagnetic antibodies. These cells were interrogated for expression of CD45 (expressed in many leukocytes;
Transitional CTCs co-expressed vimentin and CK in many of the patients with elevated CTC counts CTCs/7.5 mL by standard testing) (Table 6,
Plasticity and CTCs.
The identification of plasticity among CTCs in a significant subset of patient samples offers several important clinical opportunities. Expression of plasticity may have prognostic or predictive value in patients with metastatic cancers, especially mBC where a significant range of values were shown for plasticity. Thus, the subset of patients with very high plasticity may have a more aggressive natural history and exhibit greater resistance to systemic treatments. In terms of diagnosis and utility as predictive biomarkers the data suggested that in addition to cells expressing both epithelial and mesenchymal markers there may be an unknown number of CTCs that have moved further towards the mesenchymal pole and are EpCAM negative. These cells will be missed by the FDA approved CellSearch® System and also by the Adna Test (AdnaGen AG) system and current microfluidic technologies, which enrich for CTCs by immunoabsorbtion of cells expressing MUC1 or EpCAM. Indeed, recent studies in breast cancer have suggested that “normal” type breast cancer cell lines that overexpress both EMT and stem cell antigens (CD44+, CD24−) may lack EpCAM and are thus not detectable by currently approved CTC detection systems. Therefore it is possible that the number of CTCs in patients with metastatic cancer is much higher than currently appreciated. Identification of this additional subset of CTC can provide greater prognostic value than CTC counts as currently determined, as well as earlier detection of CTCs and the metastatic potential in patients with earlier stage disease.
Furthermore, CTCs in intermediate states, which comprise the 50-75% of cells isolated herein from patients with metastatic breast and prostate cancer as well as those cells that may go undetected because they have undergone a more complete EMT, represent a therapeutic problem. It has been well documented that EMT alters drug sensitivity of lung cancer cells and it has been challenging to direct therapy to cancer cells with stem cell-like properties, perhaps because of their recalcitrance to undergo apoptosis.
While recent studies suggest both a screening method and actual compounds (e.g., salinomycin) that can selectively target cancer stem cells, these aggressive cells still represent a formidable therapeutic challenge. Thus, molecules comprising a binding agent that has binding specificity to an EMT biomarker described herein and linked to an anti-cancer agent provide additional therapeutic options.
Eligible men had progressive metastatic CRPC (progression despite testosterone <50 ng/dL) and were about to begin a new systemic therapy. Eligible women had progressive metastatic breast cancer (mBC) and were about to begin a new systemic therapy. Baseline characteristics of patients (n=29) are presented in Table 7.
CTCs were drawn into standard FDA-approved Cellsave tubes and processed within 48 hours using the CellSearch® methodology using EpCAM-based ferromagnetic capture. A CTC was defined as an intact nucleated (DAPI+) cell that expressed pan-CK and lacked expression of the leukocyte antigen CD45, and was enumerated using standard methods. A second Cellsearch® tube was collected and processed using EpCAM capture, and isolated cells were stained for CK (IgG1, AbD Serotec) labeled with Alexa 555, CD45 (IgG1, AbCam) labeled with Alexa 647, and either vimentin (IgG1, BD Biosciences) or N-Cadherin (IgG1, DAKO) using immunoflouresent labeling with Alexa 488. The proportion of CTCs staining positive for an EMT antigen was calculated from the total number of CTCs manually scored from the second tube. Positive controls using American Red Cross-derived PBMCs (CD45), PC3 prostate cancer cells (vimentin, N-cadherin), and T47D breast cancer cells (CK) were used for each marker. Negative controls using mock antibody were used to optimize the staining/scoring of each antigen.
Prevalence of vimentin and CK co-expression in CTCs, and prevalence of N-cadherin and CK co-expression in CTCs are presented in Tables 8 and 9, respectively. Vimentin co-expression was detected in 17/20 (85%) patients with mCRPC or mBC and 78% of all CTCs. N-Cadherin co-expression was detected in 8/9 (89%) patients and 81% of CTCs. Immunofluorescent images of CTCs from patients with mCRPC and mBC are shown in
The data showed the co-expression of cytokeratin with the EMT antigens vimentin and N-cadherin in CTCs from men with metatastic CRPC and women with metastatic breast cancer. A majority of CTCs examined co-expressed CK and EMT proteins by immunofluorescent labeling. The majority of patients in this study had CTCs that co-expressed vimentin or N-cadherin suggesting potential epithelial plasticity during metastasis. The data suggests that CTCs can lack epithelial markers and provide methods for assessing patients with breast and prostate cancer as well as for the optimal detection of circulating tumor cells in other common malignancies.
In a second trial to test for the existence of transitional CTCs, blood was collected from 31 men with mCRPC and 16 women with mBC (see baseline characteristics for the patients in Table 10 and Table 11). CTCs were processed using the CellSearch® EpCAM-based immunocapture method and profiled for expression of CD45 (PTPRC) (a leukocyte marker), cytokeratins (CK) (epithelial markers), vimentin (VIM) and N-cadherin (CDH2) (mesenchymal markers), and CD133 (a stem cell marker) by immunofluorescence (IF) (Table 2). Leukocytes were defined as nucleated (DAPI positive), CD45-positive and CK-negative cells, whereas CTCs were defined as nucleated (DAPI positive), CD45-negative and CK-positive cells. Among CTCs we identified transitional cells as those that additionally expressed vimentin or N-cadherin.
1 PSA: prostate specific antigen.
2Pain is scored as a linear analog scale (0-10 range).
Among ten men with mCRPC, CTCs co-expressed vimentin and CK in 10/10 (100%) patients, and by this criterion 108/126 (86%) of enumerated CTCs were transitional (Table 12,
iThe middle column represents the CTC Count from the FDA-approved Cellsearch ® enumeration of CTCs for each subject.
iiRight column represents the ratio of vimentin (co-expression of vimentin ranged from 60-100% of cells in a given individual and did not correlate with CTC count (R2 = 0.11)), N-cadherin (Co-expression of N-cadherin ranged from 55-100% of cells in a given individual, and did not correlate with CTC count (R2 = −0.09)), or CD133 (CD133 co-expression ranged from 55-100% of evaluable cells in a given individual and did not correlate with CTC number (R2 = 0.04)) expressing CTCs among the total number of CTCs that were manually enumerated. A CTC was defined as an intact DAPI positive (nucleated) cell that lacked CD45 expression and expressed cytokeratin.
Among the next cohort of 10 men with mCRPC, CTCs co-expressed N-cadherin and CK in 10/10 (100%) patients, and by this criterion 167/206 (81%) of CTCs were identified as transitional (Table 12,
Given the expression of the stem cell associated antigen CD133 in transitional AT3-T cells, CD133 expression in CTCs from men with mCRPC was evaluated. CD133 was expressed in 11/11 (100%) men with CTCs, and in 154/180 (86%) of CTCs from these men (Table 12,
This application claims the benefit of priority to U.S. Provisional Patent Application No. 61/298,845 filed Jan. 27, 2010; U.S. Provisional Patent Application No. 61/308,780 filed Feb. 26, 2010; and U.S. Provisional Patent Application No. 61/309,131 filed Mar. 1, 2010, which are all incorporated herein by reference in their entireties.
This invention was made with government support under federal grant number 5R33CA097502 from the NIH (NCI), and federal grant number 5K12CA10063904 from the NIH (NCI). The U.S. Government has certain rights to this invention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US10/50223 | 9/24/2010 | WO | 00 | 5/1/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61298845 | Jan 2010 | US | |
| 61308780 | Feb 2010 | US | |
| 61309131 | Mar 2010 | US |
