Mikio Monji

Glypican-3, overexpressed specifically in human hepatocellular carcinoma, is a novel tumor marker

With the global pandemic of hepatitis B and C infections, the incidence of Hepatocellular carcinoma (HCC) is rapidly increasing world wide. We identified glypican-3 (GPC3), a novel oncofetal gene over-expressed specifically in human HCC, as based on data of cDNA microarrays. As GPC3 is a GPI-anchored membrane protein and could be secreted, we attempted to detect secreted GPC3 protein in sera from HCC patients using Western blotting and ELISA. GPC3 protein was positive in sera of 40.0% (16/40) of HCC patients, and negative in sera from subjects with liver cirrhosis (LC) (0/13), chronic hepatitis (CH) (0/34), and healthy donors (0/60). All subjects were Japanese. Although 12 of 40 HCC patients were negative for both alpha-fetoprotein (AFP) and PIVKA-II well known tumor markers of HCC, four of these were GPC3-positive in the sera. We also observed vanishing GPC3 protein in the sera of three patients after the surgical treatment for HCC. On the other hand, immunohistochemical analysis revealed that HCC expressed GPC3 protein in all 14 HCC patients tested. In conclusion, GPC3, as defined in this study was shown to be a useful tumor marker for cancer-diagnosis for large numbers of patients with HCC.

Identification of Glypican-3 as a Novel Tumor Marker for Melanoma

Purpose: We reported recently the novel tumor marker glypican-3 (GPC3) for hepatocellular carcinoma. In the present study, we investigated the expression of GPC3 in human melanoma cell lines and tissues and asked whether GPC3 could be a novel tumor marker for melanoma. Experimental Design: Expression of GPC3 mRNA and protein was investigated in human melanoma cell lines and tissues using reverse transcription-PCR and immunohistochemical analysis. Secreted GPC3 protein was quantified using ELISA in culture supernatants of melanoma cell lines and in sera from 91 patients with melanoma and 28 disease-free patients after surgical removal of primary melanoma. All of the subjects were Japanese nationals. Results: In >80% of melanoma and melanocytic nevus, there was evident expression of GPC3 mRNA and protein. Furthermore, GPC3 protein was evidenced in sera of 39.6% (36 of 91) of melanoma patients but not in sera from subjects with large congenital melanocytic nevus (0 of 5) and from healthy donors (0 of 60). Twenty-seven of 36 serum GPC3-positive patients were negative for both serum 5-S-cysteinyldopa and melanoma-inhibitory activity, well-known tumor markers for melanoma. The positive rate of serum GPC3 (39.6%) was significantly higher than that of 5-S-cysteinyldopa (26.7%) and of melanoma-inhibitory activity (20.9%). Surprisingly, we detected serum GPC3 even in patients with stage 0 in situ melanoma. The positive rate of serum GPC3 at stage 0, I, and II (44.4%, 40.0%, and 47.6%) was significantly higher than that of 5-S-cysteinyldopa (0.0%, 8.0%, and 10.0%). Also observed was the disappearance of GPC3 protein in sera from 11 patients after surgical removal of the melanoma. Conclusions: GPC3 is apparently a novel tumor marker useful for the diagnosis of melanoma, especially in early stages of the disorder.

Embryonic Stem Cell–Derived Dendritic Cells Expressing Glypican-3, a Recently Identified Oncofetal Antigen, Induce Protective Immunity against Highly Metastatic Mouse Melanoma, B16-F10

We have recently established a method to generate dendritic cells from mouse embryonic stem cells. By introducing exogenous genes into embryonic stem cells and subsequently inducing differentiation to dendritic cells (ES-DC), we can now readily generate transfectant ES-DC expressing the transgenes. A previous study revealed that the transfer of genetically modified ES-DC expressing a model antigen, ovalbumin, protected the recipient mice from a challenge with an ovalbumin-expressing tumor. In the present study, we examined the capacity of ES-DC expressing mouse homologue of human glypican-3, a recently identified oncofetal antigen expressed in human melanoma and hepatocellular carcinoma, to elicit protective immunity against glypican-3-expressing mouse tumors. CTLs specific to multiple glypican-3 epitopes were primed by the in vivo transfer of glypican-3-transfectant ES-DC (ES-DC-GPC3). The transfer of ES-DC-GPC3 protected the recipient mice from subsequent challenge with B16-F10 melanoma, naturally expressing glypican-3, and with glypican-3-transfectant MCA205 sarcoma. The treatment with ES-DC-GPC3 was also highly effective against i.v. injected B16-F10. No harmful side effects, such as autoimmunity, were observed for these treatments. The depletion experiments and immunohistochemical analyses suggest that both CD8+ and CD4+ T cells contributed to the observed antitumor effect. In conclusion, the usefulness of glypican-3 as a target antigen for antimelanoma immunotherapy was thus shown in the mouse model using the ES-DC system. Human dendritic cells expressing glypican-3 would be a promising means for therapy of melanoma and hepatocellular carcinoma.

Proliferation Potential-Related Protein, an Ideal Esophageal Cancer Antigen for Immunotherapy, Identified Using Complementary DNA Microarray Analysis

Purpose: To establish effective antitumor immunotherapy for esophageal cancer, we tried to identify an useful target antigen of esophageal cancer. Experimental Design: We did cDNA microarray analysis to find a novel candidate antigen, proliferation potential-related protein (PP-RP). We examined cytotoxicity against tumor cells in vitro and in vivo of CTLs specific to PP-RP established from esophageal cancer patients. Results: In 26 esophageal cancer tissues, an average of relative ratio of the expression of the PP-RP mRNA in cancer cells versus adjacent normal esophageal tissues was 396.2. Immunohistochemical analysis revealed that, in 20 of the 22 esophageal cancer tissues, PP-RP protein was strongly expressed only in the cancer cells and not so in normal esophageal epithelial cells. PP-RP protein contains 10 epitopes recognized by HLA-A24–restricted CTLs. These CTLs, generated from HLA-A24–positive esophageal cancer patients, had cytotoxic activity against cancer cell lines positive for both PP-RP and HLA-A24. Furthermore, adoptive transfer of the PP-RP–specific CTL line inhibited the growth of a human esophageal cancer cell line engrafted in nude mice. Conclusions: The expression of PP-RP in esophageal cancer cells was significantly higher than in normal cells, and the CTLs recognizing PP-RP killed tumor cells in vitro and also showed tumor rejection effects in a xenograft model. Therefore, PP-RP may prove to be an ideal tumor antigen useful for diagnosis and immunotherapy for patients with esophageal cancer. cDNA microarray analysis is a useful method to identify ideal tumor-associated antigens.

Head and neck cancer antigens recognized by the humoral immune system

Head and neck cancer in advanced stages are difficult to treat. Therefore, development of new treatment modalities and preventive measures are required. We now report the identification of human head and neck cancer antigens recognized by the humoral immune system. We used the serological analysis of recombinant cDNA expression libraries (SEREX) approach. cDNA libraries from cell lines of squamous cell carcinoma of head and neck (SCCHN) and a normal testicle tissue were screened using sera from six allogeneic SCCHN patients. Total 28 positive clones belonging to 19 different genes were identified, including 12 known genes and 7 unknown ones. Expression analysis on 13 normal tissues and 13 cancer tissues using reverse transcription-PCR (RT-PCR) revealed eight ubiquitously expressed genes, nine of which were expressed preferentially in cancer tissues and two cancer/testis antigens. These antigens we defined may be pertinent candidate antigens for future cancer-diagnosis and related immunotherapy.

Identification of a novel human cancer/testis antigen, KM-HN-1, recognized by cellular and humoral immune responses

Purpose: We used serologic screening of a cDNA expression library of human testis to identify novel cancer/testis antigens that elicit both humoral and cellular immune responses in cancer patients. Experimental Design and Results: We identified a novel gene designated KM-HN-1 the expression of which is testis-specific among normal tissues; it contains coiled coil domains and a leucine zipper motif and encodes a putative protein consisting of 833 amino acids. KM-HN-1 expression was observed in various cancer tissues and cancer cell lines at both mRNA and protein levels. Immunofluorescence staining of an esophageal cancer cell line revealed that KM-HN-1 protein was present exclusively in the nucleus during mitosis. Recombinant KM-HN-1 protein was produced, and used for ELISA to quantitate levels of IgG antibody specific to KM-HN-1. Higher levels of IgG antibodies specific to KM-HN-1 were detected in many types and numbers of cancer patients but not in healthy donors. The CTL lines specific to KM-HN-1, generated from HLA-A*2402–positive healthy donors and cancer patients, killed human leukocyte antigen (HLA)-A24-positive cancer cells expressing KM-HN-1 but not cell lines that did not express either KM-HN-1 or HLA-A24. Conclusions: We identified a novel cancer/testis antigen, KM-HN-1, which elicited humoral immune responses in patients with various types of cancer. Furthermore, KM-HN-1-specific CTLs could be generated from both healthy donors and cancer patients, which indicated that KM-HN-1 can be a candidate for an ideal target for cancer immunotherapy.

DNA vaccination of HSP105 leads to tumor rejection of colorectal cancer and melanoma in mice through activation of both CD4 T cells and CD8 T cells.

We report that HSP105, identified by serological identification of antigens by recombinant expression cloning (SEREX), is overexpressed in a variety of human cancers, including colorectal, pancreatic, thyroid, esophageal, and breast carcinoma, but is not expressed in normal tissues except for the testis. The amino acid sequences and expression patterns of HSP105 are very similar in humans and mice. In this study, we set up a preclinical study to investigate the usefulness of a DNA vaccine producing mouse HSP105 whole protein for cancer immunotherapy in vivo using BALB/c and C57BL/6 mice, Colon26, a syngeneic endogenously HSP105‐expressing colorectal cancer cell line, and B16.F10, a melanoma cell line. The DNA vaccine was used to stimulate HSP105‐specific T‐cell responses. Fifty percent of mice immunized with the HSP105 DNA vaccine completely suppressed the growth of subcutaneous Colon26 or B16.F10 cells accompanied by massive infiltration of both CD4+ T cells and CD8+ T cells into tumors. In cell transfer or depletion experiments we proved that both CD4+ T cells and CD8+ T cells induced by these vaccines play critical roles in the activation of antitumor immunity. Evidence of autoimmune reactions was not present in surviving mice that had rejected tumor cell challenges. We found that HSP105 was highly immunogenic in mice and that the HSP105 DNA vaccination induced antitumor immunity without causing autoimmunity. Therefore, HSP105 is an ideal tumor antigen that could be useful for immunotherapy or the prevention of various human tumors that overexpress HSP105, including colorectal cancer and melanoma. (Cancer Sci 2005; 96: 695 – 705)

Identification of the H2‐Kd‐restricted cytotoxic T lymphocyte epitopes of a tumor‐associated antigen, SPARC, which can stimulate antitumor immunity without causing autoimmune disease in mice

We previously reported that the secreted protein acidic and rich in cystein (SPARC) was overexpressed in melanoma in humans, and the serum SPARC level was useful as a novel tumor marker for melanoma. SPARC was also reported to be overexpressed in various human cancers. In this study, we asked whether SPARC‐specific cytotoxic T lymphocytes (CTL) could induce antitumor immunity to SPARC‐expressing tumor in mice or not as a preclinical study of SPARC‐directed anticancer immunotherapy. Because of similarities in the structural motifs of major histocompatibility complex‐binding peptides between H2‐Kd and HLA‐A24 (A*2402), the most common human leukocyte antigen class I allele in the Japanese population, we attempted to identify the H2‐Kd‐restricted SPARC epitope for CTL in BALB/c mice and we found that the mouse SPARC143–151 (DYIGPCKYI) and SPARC225–234 (MYIFPVHWQF) peptides could induce peptide‐reactive CTL in BALB/c mice without causing autoimmune diseases. The immunization of mice with SPARC225–234 peptide‐pulsed bone marrow‐derived dendritic cells (BMDC) inhibited the growth of s.c. inoculated mouse mammary cancer cell line, N2C, expressing SPARC and these mice lived longer than the mice immunized with peptide‐unpulsed BMDC. In conclusion, our study indicated that SPARC peptide‐based cancer immunotherapy was effective and safe at least in a mouse tumor prevention model. (Cancer Sci 2009; 100: 132–137)

Serum concentrations of laminin γ2 fragments in patients with head and neck squamous cell carcinoma

The laminin (LN) γ2 chain expression has been linked to tumor invasion and prognosis. To provide a convenient clinical use, procedures that analyze LNγ2 expression by using the serum and/or urine of patients should be developed.

Difficulty in the Cytodiagnosis of Mammary Analogue Secretory Carcinoma: Survey of 109 Cytologists with a Case Originating from a Minor Salivary Gland

Background: Mammary analogue secretory carcinoma (MASC) of the salivary gland shows morphologic similarities and shares an immunophenotype and characteristic ETV6-NTRK3 translocation with secretory carcinoma of the breast. We present a buccal case of MASC along with a survey-based debate about its cytologic diagnosis by fine-needle aspiration (FNA). Case: FNA of the buccal nodule of a 58-year-old Japanese man was initially performed by 3 cytologists who gave different assessments of the Papanicolaou classification (i.e., class II, III, and V). To investigate the potential for discrepant diagnosis of MASC on a larger scale, we distributed a survey with questions about the cytological diagnosis of the present case to cytologists at other institutions. A total of 109 cytologists completed the survey, providing varying assessments of the Papanicolaou classification: class I/II (14%), class III (53%), and class IV/V (33%). Most of the respondents (72%) could not identify a particular tumor or disease. Even the respondents who identified a particular tumor suggested widely differing diagnoses, from a benign lesion to various malignant tumors. Only 2 respondents correctly identified MASC. Conclusion: Our experience and the results of the survey suggest difficulty in the cytodiagnosis of MASC.