Patent Application
20240270869
The present disclosure relates to an antibody or fragment thereof, and the like. More specifically, the present disclosure relates to an antibody or fragment thereof that recognizes a colorectal cancer- or oral cancer-specific antigen, use of the antibody or fragment thereof, and the like.
Antibodies (in particular, monoclonal antibodies) are widely used for early diagnosis of cancer, specific diagnosis, screening, and identification of molecular targets for cancer treatment. In recent year, humanization of monoclonal antibodies has become feasible, and various humanized monoclonal antibodies are used in the treatment of malignant tumors and autoimmune diseases (e.g., CD3 (Orthoclone OKT3), glycoprotein IIb/IIIa receptor (ReoPro), ERBB2 (Herceptin), CD20 (Rituxan), CD25 (Zenapax and Simulect), RSVgpF (Synagis), TNF-α (Remicade), and IL-6R).
For the application of antibodies, it is necessary to establish antibodies that specifically recognize cancer-specific antigens of various tumors, and the specificity of antibodies is an important issue for the clinical application of antibodies. Many studies have been conducted to identify novel molecules specifically expressed on the surface of cancer cells or in the serum of cancer patients; however, most of the studies are not for efficiently identifying molecules or epitopes that are considered to be cancer-specific markers.
An object of the present disclosure is to provide an antibody or fragment thereof that recognizes a colorectal cancer-or oral cancer-specific antigen.
The present inventors found that antibody 12G5A reacts with human colon adenocarcinoma-derived HT-29 cells, but does not react with differentiated HT-29 cells treated with sodium butyrate (normal intestinal epithelial cells). Based on this finding, the inventors made further improvements.
The present disclosure encompasses, for example, the subject matter described in the following items.
An antibody or fragment thereof that recognizes an N-linked glycan that annexin A2 has.
The antibody or fragment thereof according to Item 1, wherein the antibody or fragment thereof is an antibody or fragment thereof of (I) or (II):
(I) an antibody or fragment thereof comprising a light-chain variable region consisting of the amino acid sequence set forth in SEQ ID NO: 1 and a heavy-chain variable region consisting of the amino acid sequence set forth in SEQ ID NO: 2; or
(II) an antibody or fragment thereof comprising a light-chain variable region consisting of an amino acid sequence having at least 90% identity to the amino acid sequence set forth in SEQ ID NO: 1 and a heavy-chain variable region consisting of an amino acid sequence having at least 90% identity to the amino acid sequence set forth in SEQ ID NO: 2.
The antibody or fragment thereof according to Item 1 or 2, wherein the annexin A2 is a protein comprising the amino acid sequence set forth in SEQ ID NO: 3.
A pharmaceutical composition comprising the antibody or fragment thereof according to any one of Items 1 to 3.
The pharmaceutical composition according to Item 4, which is for use in diagnosis of cancer or for use in treatment of cancer.
The pharmaceutical composition according to Item 5, wherein the cancer is colorectal cancer or oral cancer.
Use of annexin A2 having an N-linked glycan as a colorectal cancer or oral cancer marker.
The use according to Item 7, wherein the annexin A2 is a protein comprising the amino acid sequence set forth in SEQ ID NO: 3.
Provided is an antibody or fragment thereof that recognizes a colorectal cancer- or oral cancer-specific antigen (specifically, an N-linked glycan that annexin A2 has). Also provided is a pharmaceutical composition comprising the antibody or fragment thereof. Further provided is a method of use of annexin A2 having an N-linked glycan as a colorectal cancer or oral cancer marker.
Embodiments encompassed by the present disclosure are described in more detail below.
The present disclosure encompasses an antibody or fragment thereof that recognizes an N-linked glycan that annexin A2 has. In the present specification, the antibody or fragment thereof may be referred to as “the antibody of the present disclosure,” “the antibody fragment of the present disclosure,” “the antibody or fragment thereof of the present disclosure,” and the like.
Annexin A2 is a calcium ion (Ca2+)—and phospholipid-binding protein with a molecular weight of 36 kDa. Annexin A2 is known to show an increased expression level in cancer cells and is believed to be expressed on the cell membrane.
SEQ ID NO: 3 shows the amino acid sequence of human-derived annexin A2.
The N-linked glycan is attached to an asparagine residue of the amino acid sequence that constitutes annexin A2. In the amino acid sequence that constitutes annexin A2, the asparagine residue to which the glycan is attached may be, for example, the asparagine residue that constitutes the amino acid sequence represented by Asn-X-Ser or Asn-X-Thr (wherein X is any amino acid residue). For example, the N-linked glycan may be attached to the asparagine residue at position 62 of the amino acid sequence set forth in SEQ ID NO: 3.
The N-linked glycan includes N-acetylglucosamine (GlcNAc). Specific examples include a high-mannose type having a structure in which an oligomer of mannose is bound to diacetylchitobiose (GlcNAc-GlcNAc), a complex type having a structure in which mannose and at least one member selected from the group consisting of N-acetylglucosamine (GlcNAc), galactose, and sialic acid are bonded to diacetylchitobiose (GlcNAc-GlcNAc), a hybrid type having a structure in which the high-mannose type and the complex type are mixed with diacetylchitobiose (GlcNAc-GlcNAc), and the like.
The antibody of the present disclosure may be a polyclonal antibody or a monoclonal antibody. Of these, it is preferred that the antibody of the present disclosure is a monoclonal antibody.
Examples of isotypes of the antibody (immunoglobulin) of the present disclosure include IgA, IgD, IgE, IgG (IgG1, IgG2, IgG2a, IgG2b, IgG3, IgG4), IgM, and the like.
Regarding the origin of the antibody of the present disclosure, the antibody of the present disclosure may be, for example, a human-derived antibody, a mouse-derived antibody, a rat-derived antibody, a rabbit-derived antibody, a monkey-derived antibody, a chimpanzee-derived antibody, or the like.
The antibody of the present disclosure may be a chimeric antibody. “Chimeric antibody” refers to an antibody having a constant region that is an amino acid sequence derived from a human and a variable region that is an amino acid sequence derived from a non-human species (e.g., a mouse). The antibody of the present disclosure may also be a humanized antibody.
Examples of the antibody fragment of the present disclosure include Fab, Fab′, F (ab′)2, Fv, scFv, and the like.
The antibody or fragment thereof of the present disclosure may be (I) an antibody or fragment thereof comprising a light-chain variable region consisting of the amino acid sequence set forth in SEQ ID NO: 1 and a heavy-chain variable region consisting of the amino acid sequence set forth in SEQ ID NO: 2. In the present specification, the antibody or fragment thereof may be referred to as “the antibody or fragment thereof (I) of the present disclosure.”
The antibody or fragment thereof of the present disclosure may be (II) an antibody or fragment thereof comprising a light-chain variable region consisting of an amino acid sequence having at least 90% identity to the amino acid sequence set forth in SEQ ID NO: 1 and a heavy-chain variable region consisting of an amino acid sequence having at least 90% identity to the amino acid sequence set forth in SEQ ID NO: 2. In the present specification, the antibody or fragment thereof may be referred to as “the antibody or fragment thereof (II) of the present disclosure.”
In the antibody or fragment thereof (II) of the present disclosure, the identity to the amino acid sequence set forth in SEQ ID NO: 1 is, for example, preferably at least 90%, and more preferably at least 95%.
In the antibody or fragment thereof (II) of the present disclosure, the identity to the amino acid sequence set forth in SEQ ID NO: 2 is, for example, preferably at least 90%, and more preferably at least 95%.
The identity of the amino acid sequence can be calculated with default parameters of homology algorithm BLAST (Basic Local Alignment Search Tool) of the National Center for Biotechnology Information (NCBI) in the US (http://www.ncbi.nlm.nih.gov/BLAST/).
The antibody or fragment thereof (II) of the present disclosure may comprise a light-chain variable region consisting of an amino acid sequence in which at least one amino acid is deleted, substituted, or added in the amino acid sequence set forth in SEQ ID NO: 1, and a heavy-chain variable region consisting of an amino acid sequence in which at least one amino acid is deleted, substituted, or added in the amino acid sequence set forth in SEQ ID NO: 2.
In each of the amino acid sequences in which at least one amino acid is deleted, substituted, or added, the upper limit of the number of amino acids deleted, substituted, or added is, for example, 25, and preferably about 10.
More specifically, the number of amino acids deleted, substituted, or added in the amino acid sequence set forth in SEQ ID NO: 1 may be, for example, 1 to 18, 1 to 15, 1 to 10, 1 to 5, or 1 to 3.
More specifically, the number of amino acids deleted, substituted, or added in the amino acid sequence set forth in SEQ ID NO: 2 may be, for example, 1 to 24, 1 to 20, 1 to 18, 1 to 15, 1 to 10, 1 to 5, or 1 to 3.
It is known in this technical field how to make a mutation such as deletion, substitution, or addition of at least one amino acid in a specific amino acid sequence, and any technique can be used. Such a mutation can be made by using, for example, the restriction enzyme treatment; the treatment using an exonuclease, DNA ligase, etc.; site-directed mutagenesis; or random mutagenesis.
When at least one amino acid is substituted, the substitution of the amino acid may be a conservative substitution. In the present specification, “conservative substitution” means the substitution of an amino acid with an amino acid having a side chain with properties similar to those of the side chain of the amino acid. Specific examples of conservative substitutions include substitutions between amino acid residues having a basic side chain, such as lysine, arginine, and histidine; substitutions between amino acid residues having an acidic side chain, such as aspartic acid and glutamic acid; substitutions between amino acid residues having an uncharged polar side chain, such as glycine, asparagine, glutamine, serine, threonine, tyrosine, and cysteine; substitutions between amino acid residues having a nonpolar side chain, such as alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, and tryptophan; substitutions between amino acid residues having a ß-branched side chain, such as threonine, valine, and isoleucine; substitutions between amino acid residues having an aromatic side chain, such as tyrosine, phenylalanine, tryptophan, and histidine; and the like.
In the amino acid sequence having at least 90% identity to the amino acid sequence set forth in SEQ ID NO: 1 in the antibody or fragment thereof (II) of the present disclosure, for example, the amino acid sequence at position 1 to position 10, the amino acid sequence at position 100 to position 107, or the amino acid sequence at position 125 to position 136 in the amino acid sequence set forth in SEQ ID NO: 1 may be conserved. Any one of the amino acid sequences may be conserved, any two of the amino acid sequences may be conserved, or all three of the amino acid sequences may be conserved. It is preferred that the amino acid sequence at position 100 to position 107 in the amino acid sequence set forth in SEQ ID NO: 1 is conserved.
In the amino acid sequence having at least 90% identity to the amino acid sequence set forth in SEQ ID NO: 2 in the antibody or fragment thereof (II) of the present disclosure, for example, the amino acid sequence at position 1 to position 6, the amino acid sequence at position 47 to position 54, the amino acid sequence at position 71 to position 77, or the amino acid sequence at position 118 to position 144 in the amino acid sequence set forth in SEQ ID NO: 2 may be conserved. Any one of the amino acid sequences may be conserved, any two of the amino acid sequences may be conserved, any three of the amino acid sequences may be conserved, or all four of the amino acid sequences may be conserved. It is preferred that the amino acid sequence at position 47 to position 54 in the amino acid sequence set forth in SEQ ID NO: 2 or the amino acid sequence at position 71 to position 77 in the amino acid sequence set forth in SEQ ID NO: 2 is conserved.
The antibody of the present disclosure can be prepared by a known method. For example, a polyclonal antibody can be prepared by immunizing a mammal with a lysate of cells that express annexin A2 having an N-linked glycan (e.g., colorectal cancer cells) or the like as an immunizing antigen, or, for example, a monoclonal antibody can be prepared by preparing a hybridoma.
The antibody fragment of the present disclosure can be prepared by a known method. For example, the antibody fragment of the present disclosure can be obtained by treating the antibody obtained by any of the methods described above with an enzyme.
The present disclosure also includes a pharmaceutical composition comprising the antibody or fragment thereof. In the present specification, the pharmaceutical composition may be referred to as “the pharmaceutical composition of the present disclosure.”
The pharmaceutical composition of the present disclosure may comprise one of the aforementioned antibodies or fragments thereof alone, or may comprise two or more of the aforementioned antibodies or fragments thereof in combination.
The content of the antibody or fragment thereof in the pharmaceutical composition of the present disclosure is not particularly limited and can be appropriately set to not greater than 100 mass %. For example, the content of the antibody or fragment thereof may be about 0.0001 to 99.9 mass %.
The pharmaceutical composition of the present disclosure comprises the antibody or fragment thereof and may further comprise other components. Examples of the other components include pharmaceutically acceptable base substances, carriers, solvents, dispersants, emulsifying agents, buffers, stabilizers, excipients, binders, disintegrators, lubricants, thickeners, antioxidants, preservatives, coating agents, coloring agents, gastric mucosal protective agents, and like drugs. These components may be used singly or in a combination of two or more.
The dosage form of the pharmaceutical composition of the present disclosure is not particularly limited. Examples include tablets, pills, capsules, powders, fine granules, granules, liquids, troches, jellies, injections, plasters, extracts, suppositories, suspensions, tinctures, ointments, poultices, nasal drops, inhalants, liniments, lotions, aerosols, and the like.
The pharmaceutical composition of the present disclosure can be prepared according to a usual method by using the antibody or fragment thereof, if necessary in combination with other components.
As shown in the Examples described later, the antibody or fragment thereof of the present disclosure reacts with cancer cells or cancer tissues, but does not react with normal cells or tissues. That is, since the antibody or fragment thereof of the present disclosure specifically reacts with cancer cells or cancer tissues, the pharmaceutical composition of the present disclosure can be suitably used for diagnosis of cancer. In the present specification, the pharmaceutical composition for diagnosis of cancer may be referred to as “the pharmaceutical composition for diagnosis of cancer of the present disclosure.”
When the pharmaceutical composition of the present disclosure is used for diagnosis of cancer, it is preferred that the antibody or fragment thereof is labeled with a labeling substance, such as an enzyme (e.g., horseradish peroxidase (HRP), alkaline phosphatase (ALP), or ß-D-galactosidase) or a fluorescent dye.
The pharmaceutical composition for diagnosis of cancer of the present disclosure can be used for diagnosing the presence or absence of cancer and the degree of cancer by reacting with a biological sample, and checking the presence or absence and degree of immune reaction.
Examples of cancers targeted by the pharmaceutical composition for diagnosis of cancer of the present disclosure include colorectal cancer such as colon cancer and rectal cancer; oral cancer such as squamous cell carcinoma; and the like. Thus, the pharmaceutical composition for diagnosis of cancer of the present disclosure is suitable as a composition for diagnosis of colorectal cancer. The pharmaceutical composition for diagnosis of cancer of the present disclosure is also suitable as a composition for diagnosis of oral cancer.
Examples of biological samples include body fluids, tissues, cells, and the like collected from a subject. Examples of body fluids include urine, serum, plasma, blood (whole blood), large-intestinal fluid, saliva, cerebrospinal fluid, synovial fluid, lymph fluid, amniotic fluid, ascitic fluid, pleural effusion, milk, bile, various tissue fluids, and the like. Examples of tissues include large-intestinal tissues, such as colon tissues and rectal tissues; oral tissues; and the like. Examples of cells include epithelial cells, mucosal cells, and the like.
The subject from which the biological sample is collected is preferably a mammal. Not only humans, but also non-human mammals can be used as subjects. Examples of human subjects include cancer patients, humans suspected of having cancer, and the like. Specific examples of cancers include colorectal cancer such as colon cancer and rectal cancer; oral cancer such as squamous cell carcinoma; and the like. Examples of non-human mammals include mammals kept as pet animals, livestock, laboratory animals, etc. Specific examples of such non-human mammals include dogs, cats, monkeys, bovine, horses, sheep, goats, pigs, rabbits, mice, rats, camels, llamas, and the like.
The method of collecting a biological sample is not particularly limited and can be any method known in this technical field.
The method of reacting the pharmaceutical composition for diagnosis of cancer of the present disclosure with a biological sample is not particularly limited and can be any method known in this technical field.
The presence or absence and degree of immune reaction can be checked, for example, by detecting a signal from a labeling substance described above. The method of detecting a signal is not particularly limited and can be any method known in this technical field.
As shown in the Examples described later, it has been confirmed that the overall survival rate and progression-free survival (PFS) of humans diagnosed with colorectal cancer worsen when the immunoreactivity to the antibody or fragment thereof of the present disclosure is high. Thus, the prognosis of colorectal cancer can be diagnosed (predicted) by comparing the immunoreactivity to the antibody or fragment thereof of the present disclosure with a set reference value. That is, the pharmaceutical composition for diagnosis of cancer of the present disclosure (more specifically, the pharmaceutical composition for diagnosis of colorectal cancer) can be more suitably used for diagnosis (prediction) of prognosis of colorectal cancer.
The immunoreactivity can be evaluated, for example, by the proportion of cells in which a signal from a labeling substance is detected (in other words, the proportion of cells expressing annexin A2 having an N-linked glycan relative to the total number of cells).
For example, a proportion of 50% or more can be set as a reference value. The immunoreactivity in a biological sample collected from the same subject in the past can also be used as a reference value.
When the immunoreactivity in a biological sample is higher than the reference value, it is predicted that there is a possibility that the prognosis of colorectal cancer in a subject from whom the biological sample was collected will worsen. On the other hand, when the immunoreactivity in a biological sample is lower than the reference value, it is predicted that there is a possibility that the prognosis of colorectal cancer in a subject from whom the biological sample was collected will be good.
As shown in the Examples described later, the antibody or fragment thereof of the present disclosure reacts not only with oral squamous cell carcinoma, but also with dysplastic epithelium. Thus, the pharmaceutical composition for diagnosis of cancer (more specifically, the pharmaceutical composition for diagnosis of oral cancer) of the present disclosure can be more suitably used for diagnosis of a precancerous lesion of oral cancer. Examples of precancerous lesions include epithelial dysplasia and the like.
As shown in the Examples described later, the antibody or fragment thereof of the present disclosure reacts with cancer cells or cancer tissues, but does not react with normal cells or tissues. Thus, since the antibody or fragment thereof of the present disclosure specifically reacts with cancer cells or cancer tissues, the pharmaceutical composition of the present disclosure can be suitably used for the treatment of cancer. In the present specification, the pharmaceutical composition for the treatment of cancer may be referred to as “the pharmaceutical composition for the treatment of cancer of the present disclosure.”
For example, as shown in the Examples described later, the antibody or fragment thereof of the present disclosure has a tumor volume suppression effect. Thus, the pharmaceutical composition of the present disclosure, which comprises the antibody or fragment thereof of the present disclosure, can be suitably used for the treatment of cancer.
In addition, for example, the pharmaceutical composition for the treatment of cancer of the present disclosure may further comprise a compound having a therapeutic effect on cancer. The compound may be attached to the antibody or fragment thereof. In other words, for example, an antibody-drug conjugate (ADC) or the like may be used.
Examples of cancers targeted by the pharmaceutical composition for the treatment of cancer of the present disclosure include colorectal cancer such as colon cancer and rectal cancer; oral cancer such as squamous cell carcinoma; and the like. Thus, the pharmaceutical composition for the treatment of cancer of the present disclosure is suitable as a composition for the treatment of colorectal cancer. The pharmaceutical composition for the treatment of cancer of the present disclosure is also suitable as a composition for the treatment of oral cancer.
The subject that takes the pharmaceutical composition for the treatment of cancer of the present disclosure is preferably a mammal. Not only humans, but also non-human mammals can be used as subjects. Examples of human subjects include cancer patients, humans suspected of having cancer, and the like. Specific examples of cancers include colorectal cancer such as colon cancer and rectal cancer; oral cancer such as squamous cell carcinoma; and the like. Examples of non-human mammals include mammals kept as pet animals, livestock, laboratory animals, etc. Specific examples of such non-human mammals include dogs, cats, monkeys, bovine, horses, sheep, goats, pigs, rabbits, mice, rats, camels, llamas, and the like.
Examples of administration methods for the pharmaceutical composition for the treatment of cancer of the present disclosure include oral administration, parenteral (e.g., intravenous, intraarterial, intramuscular, subcutaneous, intraperitoneal, rectal, transdermal, and local) administration, and the like.
The dose (intake) of the pharmaceutical composition for the treatment of cancer of the present disclosure is not particularly limited and is determined according to the age, body weight, sex, and severity of symptoms of a subject to which the pharmaceutical composition is administered, the administration method, etc.
The present disclosure also includes use of annexin A2 having an N-linked glycan as a colorectal cancer marker.
The present disclosure also includes use of annexin A2 having an N-linked glycan as an oral cancer marker.
As described above, since the antibody or fragment thereof of the present disclosure recognizes the N-linked glycan that annexin A2 has, cancer can be diagnosed by evaluating the immunoreactivity. Thus, annexin A2 having an N-linked glycan is suitably used as a cancer marker.
Use of the cancer marker, more specifically, a colorectal cancer marker, enables diagnosis of colorectal cancer, diagnosis of prognosis of colorectal cancer, and the like, as described above.
Use of the cancer marker, more specifically, an oral cancer marker, enables diagnosis of oral cancer, diagnosis of a precancerous lesion of oral cancer, which is difficult to confirm even by histopathological diagnosis at present, and the like, as described above.
In the present specification, the term “comprising” includes “consisting essentially of” and “consisting of.” Further, the present disclosure includes any and all combinations of the elements described herein.
Various characteristics (properties, structures, functions, etc.) described in the above embodiments of the present disclosure may be combined in any manner to specify the subject matter included in the present disclosure. That is, this disclosure includes all of the subject matter comprising any combination of the combinable properties described herein.
The contents of the present disclosure are described in detail with reference to the following Experimental Examples. However, the present disclosure is not limited thereto. In the following, experiments were performed at atmospheric pressure and ordinary temperature, unless otherwise specified. The term “%” indicates “mass %,” unless otherwise specified. The amount of each component shown in each table is also shown as “mass %,” unless otherwise specified.
Human colon adenocarcinoma-derived HT-29 cells were cultured with 1 mM sodium butyrate (Tokyo Chemical Industry Co., Ltd., Tokyo, Japan) for 48 hours to induce differentiation. As an index of cell differentiation, alkaline phosphatase activity was measured using p-nitrophenyl phosphate (Sigma-Aldrich, St. Louis, MO, USA) as a substrate at 37° C. for 15 minutes. The reaction was stopped by the addition of NaOH. The amount of p-nitrophenol was determined by measuring absorbance at 405 nm.
Five BALB/c mice were immunized intraperitoneally every week with 1×107 HT-29 cells induced with sodium butyrate. Serum was obtained from the mice after the third immunization. IgG was purified from the serum using a HiTrap Protein G HP column (GE Healthcare, Germany) and bound to M-270 epoxy magnetic beads according to the manufacturer's protocol. Cell lysate proteins were isolated from HT-29 cells (without sodium butyrate treatment) using a cell lysis buffer. The solubilized protein mixture was adsorbed to the M-270 epoxy magnetic beads containing an antibody against the sodium butyrate-induced HT-29 cells, and then used for immunization to generate a monoclonal antibody.
A monoclonal antibody was generated according to the hybridoma technology of Kohler and Milstein. Hybridoma clones were screened using the following two-step process and isolated by limiting dilution.
Clones producing an antibody that reacted with HT-29 cells but did not react with sodium butyrate-treated differentiated HT-29 cells were first selected by immunofluorescence staining.
Subsequently, whether formalin-fixed, paraffin-embedded colorectal cancer tissue sections and oral cancer can be immunostained with candidate antibodies was investigated. The subclass of the antibodies was determined using IsoQuick (EnviroLogix, Inc., Portland, ME, USA). The antibodies were purified from culture supernatants using ImmunoAssist MG-PP (Kanto Chemical Co., Inc., Tokyo, Japan).
Cells were fixed with 4% (m/v) paraformaldehyde, permeabilized with 0.1% TritonX-100, and blocked with 10% goat serum. Thereafter, the cells were incubated using a culture supernatant containing 12G5A and then cultured using an Alexa Fluor 488-conjugated anti-mouse antibody. Images were acquired using a confocal laser scanning microscope (Leica TCS SP8, Germany). The 12G5A immunoreactivity was visualized with green fluorescence, and the nuclei were stained with DAPI.
It was confirmed that HT-29 colon cancer cells (
As shown in
Regarding the monoclonal antibody (12G5A), the amino acid sequence (SEQ ID NO: 1) of the light-chain variable region and the amino acid sequence (SEQ ID NO: 2) of the heavy-chain variable region were analyzed by sequence analysis (
Purified antibody 12G5A was bound to M-270 epoxy magnetic beads according to the manufacturer's protocol. 12G5A antigen was obtained from a cell lysate of SW480 cells by affinity chromatography using the M-270 epoxy magnetic beads to which antibody 12G5A was bound. The approximately 40 kDa protein band was stained with a Coomassie Brilliant Blue staining kit (Integrale, Tokushima, Japan), excised from the SDS-PAGE gel, digested with trypsin, and analyzed with MALDI-TOF MASS SPEC ANALYSIS (Genomine, Seoul, Korea).
The results of MALDI-TOF mass spectrometry suggest that the approximately 40 kDa protein is human annexin A2.
siRNA-Mediated Gene Silencing
For silencing of annexin A2, Thermo Fisher Scientific siRNA (Waltham, MA, USA), Cat No. 4390824: s1383 and s9548 was used. Trilencer-27 Universal scrambled negative control siRNA (OriGene Technologies, Rockville, MD, USA) was used as a non-silencing control. Cells were transfected with the siRNAs using Lipofectamine (trademark) RNAiMAX (Invitrogen, Carlsbad, CA, USA) according to the manufacturer's instructions. The cells were used for subsequent studies 48 hours after transfection.
Proteins were electrophoresed on a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel and electroblotted onto a polyvinylidene difluoride membrane (Millipore, Bedford, MA, USA). The membrane was blocked with Block Ace (blocking milk; Yukijirushi, Sapporo, Japan) and then incubated with 0.5 g/ml of 12G5A or anti-GAPDH antibody (Sigma-Aldrich, St. Louis, MO, USA). The immunoreactivity was evaluated using a Western blotting detection kit (Promega, Madison, WI, USA).
The results of siRNA targeting and immunoblotting confirmed that 12G5A reacted with annexin A2.
Patients and Histopathological Classification After receiving approval from the Institutional Review Board of the Gifu University Graduate School of Medicine (specific approval numbers: 2019-202, 2019-0444, 28-421, 2019-157, and 28-524) to carry out study, 55 specimens were collected from surgically treated patients who were primarily diagnosed with colorectal cancer.
All of the 55 primary tumors were examined macroscopically and microscopically to determine the depth of invasion, lymph node status, and distant metastasis to TNM classification. Invasion into lymphatic and blood vessels was determined according to Japanese classification of colorectal cancer 8th edition. In this classification, the status of cancer invasion to lymphatic (ly) and blood vessels (v) was histopathologically determined as ly0 and v0 (no invasion); ly1 and v1 (mild invasion); ly2 and v2 (moderate invasion); and ly3 and v3 (severe invasion). The infiltrative pattern of cancer was histopathologically classified as INFa (expansive growth), INFb (intermediate type), and INFc (infiltrative growth).
A rabbit monoclonal antibody against annexin A2 was purchased from CST (D11G2, Cambridge, MA, USA). All tissue specimens were fixed with 10% buffered formalin and embedded in paraffin. The tissues were immunostained as described above. Briefly, deparaffinized tissue slices were incubated in 10% normal goat serum for 30 minutes. Subsequently, the slides were incubated with 2 μg/ml of antibody 12G5A or D11G2 for 1 hour at room temperature or overnight at 4° C. For 12G5A, the tissue specimens were incubated with a goat anti-murine immunoglobulin u chain antibody conjugated with horseradish peroxidase (1:200) (Abcam, cat #ab98679; Cambridge, MA, USA). For D11G2, the tissues were immunostained with an antibody attached to ImmPRESS (trademark) polymerized reporter enzyme staining system (Vector Laboratories, Burlingame, CA, USA). Finally, the reaction was developed with 3,3′-diaminobenzidine, and counter staining was performed with hematoxylin.
The results obtained from immunohistochemical staining were expressed as a percentage calculated as the proportion of immunoreactive colorectal cancer cells relative to the total number of cells. The proportion of 12G5A immunoreactivity positive cells was determined by scoring 10 high-power fields for each sample. In staining, the immunoreactivity was considered “low” if less than 50% of the cancer cells exhibited immunoreactivity and “high” if 50% or more of the cancer cells exhibited immunoreactivity.
Table 1 shows the relationship between 12G5A immunoreactivity and clinical pathological features in 24 cases with low 12G5A immunoreactivity and 31 cases with high 12G5A immunoreactivity.
Overall survival (OS) and progression-free survival (PFS) curves were drawn using the Kaplan-Meier method, and differences in survival rates were compared using the log-rank test for univariate survival analysis. Multivariate Cox proportional hazards regression analysis was also performed to calculate the hazard ratio of death for 12G5A epitope expression.
μLog-rank p-value
As shown in
In addition, as shown in Table 2, multivariate analysis of survival risk showed that 12G5A immunoreactivity was not independently associated with prognosis (it was correlated with the T factor of colorectal cancer and thus not an independent prognostic factor).
The specimen used in
No staining was observed in oral non-neoplastic stratified squamous epithelium (A), whereas staining was observed in dysplastic epithelium (B) or oral squamous cell carcinoma (C).
Dysplastic epithelium is a precancerous state, and 12G5A was found to be immunoreactive not only to cancer cells but also to cells in a precancerous state.
Glycopeptidase F was purchased from Takara Bio, Inc. 0-glycosidase and α2-3,6,8 neuraminidase were obtained from New England Biolabs (Beverly, MA, USA). Enzymatic deglycosylation of cell lysate protein was performed according to the manufacturer's protocol.
Glycopeptidase F specifically cleaves the binding site (GlcNAc-Asn bond) between an N-glycan and a protein. However, glycopeptidase F does not act on glycans in which Fuca1-3 is attached to GlcNAc that is attached to Asn.
O-glycosidase cleaves Core 1 and Core 3 O-linked disaccharides from glycoproteins.
α2-3,6,8 neuraminidase cleaves α2-3, α2-6, and α2-8 linked N-acetylneuraminic acid residues from glycoproteins and oligosaccharides with high specificity. The cleavage efficiency of α2-8 linkages is lower than that of α2-3 and α2-6 linkages.
As shown in
SW480 cells were also incubated with or without 5 μg/ml of tunicamycin (Fujifilm Wako Pure Chemical Corporation, Osaka, Japan) for 48 hours to evaluate the effect of inhibition of N-linked glycosylation on immunofluorescence staining.
Inhibition of N-linked glycosylation by tunicamycin abolished 12G5A immunoreactivity, shown in green, in SW480 cells (
These results suggest that 12G5A recognizes an N-linked glycosylation-modified tumor-associated epitope of annexin A2.
Colorectal Cancer Tumor Suppression Effect On Day 0, 0.93×107 SW480 colorectal cancer cells were subcutaneously implanted in BALB/c nu/nu mice, and on Day 11 and Day 37, an antibody was administered (12G5A 0.9 mg/mouse). The tumor volume was measured over time (6 mice). The tumor volume was also measured in a group to which the antibody was not administered (MOCK, 5 mice).
As shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021052723 | Mar 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/013783 | 3/24/2022 | WO |
