Emiri Nakazawa

Prognostic significance of HLA class I expression in osteosarcoma defined by anti‐pan HLA class I monoclonal antibody, EMR8‐5

With the goal of establishing efficacious peptide‐based immunotherapy for patients with bone and soft tissue sarcomas, we previously identified the cytotoxic T lymphocyte‐defined osteosarcoma antigenic gene Papillomavirus binding factor. The present study was designed to determine the status of HLA class I expression in osteosarcoma and other bone and soft tissue sarcomas. Seventy‐four formalin‐fixed paraffin‐embedded specimens of various bone and soft tissue sarcomas, including 33 osteosarcomas, were stained with the anti‐HLA class I monoclonal antibody EMR8‐5, which we recently generated. The expression of HLA class I was lost or downregulated in 46 of these specimens (62%). With respect to osteosarcoma, loss or downregulation of HLA class I expression was seen in 13 (52%) of 25 primary tumors and seven (88%) of eight metastatic tumors. In six of 11 HLA class I‐negative osteosarcoma specimens, the expression of β‐2 microglobulin was also lost. Subsequently the prognostic significance of HLA class I expression was analyzed in 21 patients with osteosarcoma who had completed multidrug neoadjuvant chemotherapy and undergone adequate surgery. Patients with osteosarcoma highly expressing HLA class I showed significantly better overall and event‐free survival than those with HLA class I‐negative osteosarcoma. In contrast, such prognostic significance of HLA class I expression was not found in 15 patients with malignant fibrous histiocytoma of soft tissue. These findings suggest that the class I‐restricted cytotoxic T lymphocyte pathway plays a major role in immune surveillance of patients with osteosarcoma. (Cancer Sci 2006; 97: 1374–1380)

Cep55/c10orf3, a tumor antigen derived from a centrosome residing protein in breast carcinoma.

Identification of tumor-associated antigens may facilitate vaccination strategies to treat patients with malignant diseases. We have found that the centrosomal protein, Cep55/c10orf3 acts as a novel breast carcinoma-associated tumor-associated antigen. Cep55/c10orf3 mRNA was detectable in a wide variety of tumor cell lines. Expression was barely detectable in normal tissues except for testis and thymus. Moreover, Cep55/c10orf3 protein could be detected by a monoclonal anti-Cep55/c10orf3 antibody (♯11-55) in 69.8% of breast carcinoma, 25% of colorectal carcinoma, and 57.8% of lung carcinoma tissues. The expression of Cep55/c10orf3 protein did not show any relationship with the hormone receptors such as estrogen receptor and progesterone receptor or expression patterns of p185HER2/neu. We designed 11 peptides which displayed a human leukocyte antigen-A24 binding motif. One Cep55/c10orf3-peptide, Cep55/c10orf3_193(10) (VYVKGLLAKI), induced cytotoxic T lymphocytes (CTLs) in 3 of 3 patients with Cep55/c10orf3 (♯11-55)-positive breast carcinoma. A Cep55/c10orf3_193(10)-specific CTL clone could also recognize Cep55/c10orf3 (+) displayed on human leukocyte antigen-A24 (+) cancer cell lines. These data indicate that Cep55/c10orf3 peptides were naturally presented by breast cancer cells and can cause CTL clonal expansion in vivo. Monoclonal antibody ♯11-55 and the Cep55/c10orf3_193(10) peptides may be useful as part of a therapeutic strategy for hormonal therapy or anti-p185HER2/neu monoclonal antibody therapy-resistant breast carcinoma patients.

Establishment of a monoclonal anti-pan HLA class I antibody suitable for immunostaining of formalin-fixed tissue : Unusually high frequency of down-regulation in breast cancer tissues

A novel monoclonal anti‐pan human leukocyte antigen (HLA) class I heavy chain antibody, EMR8‐5, was established. It could detect HLA‐A, ‐B, and ‐C antigens in formalin‐fixed paraffin embedded tissues. By immunohistochemical staining using the EMR8‐5 antibody, various cancer tissues from 246 cases were examined for HLA class I expression. It was found that HLA class I expression was decreased in 20% to 42% of the cases of lung cancer, hepatocellular carcinoma, colon cancer, renal cell carcinoma, and urothelial carcinoma. In contrast, 85% of breast cancer cases had loss of or decreased HLA class I expression. Of the 35 breast cancer cases that had decreased HLA class I heavy chain expression, 33 (94%) also had decreased beta2‐microglobulin expression detected by immunohistochemical staining. It was suggested that HLA class I down‐regulation might be a common characteristic of breast cancer mostly caused by the down‐regulation of beta2‐microglobulin expression.

The feasibility of Cep55/c10orf3 derived peptide vaccine therapy for colorectal carcinoma.

In our previous study, we demonstrated that a peptide derived from the novel centrosome residing protein Cep55/c10orf3 can be targeted by the cytotoxic T lymphocytes (CTLs) in peripheral blood mononuclear cells (PBMCs) of breast carcinoma patients. In this report, we evaluated the feasibility of cancer immunotherapy using Cep55/c10orf3 peptide for colorectal carcinoma (CRC). To evaluate the expression of Cep55/c10orf3 in CRC tissues, we performed immunohistochemical staining of using anti-Cep55/c10orf3 monoclonal antibody. Sixty-three percent cases showed weak positive for Cep55/c10orf3 in total 70 CRC cases. The Cep55/c10orf3 expression intention was collated with high histological grade of CRC. Thus, we hypothesized that Cep55/c10orf3 can also be the target of CTLs in CRC cases. We generated CTLs from PBMCs of human leukocyte antigen (HLA)-A24-positive colorectal carcinoma patients using HLA-A24-restricted Cep55/c10orf3 peptides. Two of 6 colorectal cancer patients were reactive for the Cep55/c10orf3_193(10) peptide, which was the only immunogenic peptide in breast carcinoma patients. CTL clone specific for Cep55/c10orf3_193(10) recognized and lysed HLA-A24 (+) and Cep55/c10orf3 (+) colorectal carcinoma cell lines. In addition, 1 of 6 colorectal carcinoma patients was reactive for the Cep55/c10orf3_402(11) and Cep55/c10orf3_283(12) peptides, but not for Cep55/c10orf3_193(10) with the ELISPOT assay. These observations suggest that the antigenic peptide repertoire presented by HLA-A24 in colorectal carcinoma might be different from that in breast carcinoma. Thus, these peptide vaccination peptide mixture of Cep55/c10orf3_193(10), Cep55/c10orf3_402(11) and Cep55/c10orf3_283(12) might be more effective than a single peptide in the treatment of colorectal carcinoma patients.

Novel spliced form of a lens protein as a novel lung cancer antigen, Lengsin splicing variant 4.

A glutamine synthetase I family protein, Lengsin, was previously identified as a novel lens‐specific transcript in the vertebrate eye. In this report, we show for the first time that Lengsin is a novel tumor‐associated antigen expressed ectopically in lung cancer. Interestingly, a novel spliced form of human Lengsin termed ‘splicing variant 4’, gaining exon 3 that codes extra 63 amino acids, is the dominant transcript form in lung cancer cells. Lengsin mRNA could be detected in 7 of 12 (58%) lung cancer cell lines and 7 of 7 (100%) surgically resected lung cancer tissues. On the other hand, Lengsin transcripts could not be detected in normal major tissues or in other cancer cell lines, including melanoma, colorectal carcinoma, breast carcinoma and hepatocellular carcinoma. In addition, knockdown of Lengsin mRNA with RNAi caused cell death and a decrease of cell viability, suggesting that Lengsin has some essential role in cell survival. Since the lens is an immune‐privileged site, we regard Lengsin as a highly immunogenic cancer antigen. Anti‐Lengsin autoantibodies were detectable in sera of lung cancer patients, although these patients did not show any lens‐related disturbances. Hence, Lengsin splicing variant 4 might be an immunogenic lung cancer‐specific antigen that is suitable as a diagnostic marker and for molecular targeting therapy, including immunotherapy. (Cancer Sci 2009)

ECRG4 is a negative regulator of caspase-8-mediated apoptosis in human T-leukemia cells.

We previously established Fas-resistant variant clones from the human T-cell leukemia lines Jurkat and SUP-T13. Comparative gene expression analysis of the Fas-resistant and Fas-sensitive clones revealed several genes that were aberrantly expressed in the Fas-resistant clones. One of the genes, esophageal cancer-related gene 4 (ECRG4), contained a VDAC2-like domain that might be associated with apoptotic signals. In the present study, we examined the subcellular localization and function of ECRG4 in Fas-mediated apoptosis. By confocal fluorescence microscopy, ECRG4-EGFP fusion protein was detected in mitochondria, endoplasmic reticulum and the Golgi apparatus in gene-transfected HeLa cells. Overexpression of ECRG4 in Fas-sensitive Jurkat cells inhibited mitochondrial membrane permeability transition, leading to resistance against Fas-induced apoptosis. Tumor necrosis factor-alpha-induced apoptosis was also suppressed in ECRG4-overexpressing Jurkat cells. Immunoprecipitation assay demonstrated that ECRG4 is associated with procaspase-8. The inhibitory mechanism included the inhibition of caspase-8 activity and Bid cleavage. Since ECRG4 expression is downregulated in activated T cells, our results suggest that ECRG4 is a novel antiapoptotic gene which is involved in the negative regulation of caspase-8-mediated apoptosis in T cells.

Expression of ECRG4 is associated with lower proliferative potential of esophageal cancer cells.

We have shown that ECRG4 suppressed Fas‐induced apoptosis in Jurkat cells. ECRG4 mRNA expression was ubiquitously detected in normal adult human tissues, suggesting that ECRG4 plays a major role in human tissues. ECRG4 mRNA expression was down‐regulated in tumor cells. Expression of ECRG4 suppressed cell growth. We established an anti‐ECRG4 monoclonal antibody. Our immunohistochemical analysis demonstrated that ECRG4‐positive cells tended to be distributed in the region that was negative for Ki‐67 in esophageal squamous cell carcinoma tissues. There was a significant inverse correlation between ECRG4 expression and Ki‐67 labeling index in esophageal squamous cell carcinoma. This study provides the first functional evidence for an association of endogenous expression of ECRG4 with cell proliferation. ECRG4 is a candidate tumor suppressor gene that might be involved in the proliferation of esophageal squamous cell carcinoma.

Development of Q-dot MHC/Peptide Multimer for Highly Sensitive Detection of Peptide-Specific T Cells

Sensitive Detection of Peptide-Specific T Cells Kumiko Shimozawa, Toshihiko Torigoe, Emiri Nakazawa, Noriyuki Sato. Cancer Vaccine Laboratory, Innovation Plaza Hokkaido, Japan Science and Technology Agancy, Sapporo, Japan; Pathology, Sapporo Medical University, Sapporo, Japan. Introduction: Tetrameric MHC/peptide complexes (teteramer) are important tools for detecting antigen-specific T cells. Tetramers are widely used to monitor immune responses in peptide vaccine therapies based on CTL-defined tumor antigens. However, frequencies of tetramer-positive CD8+ T cells in fresh peripheral blood mononuclear cells (PBMCs) are very low, and that makes it difficult to evaluate the effect of vaccination sequentially in individual cases. We developed novel MHC/peptide multimers using a new fluorescent nano-particle, QdotTM, which had strong fluorescence intensity. We compared the sensitivity and specificity of Qdot-multimer with those of PE-tetramer. Methods: Biotinylated MHC/peptide monomers were multimerized with Qdot655 -streptavidin. The peptides used for the multimers or the tetramers were TYGPVFMSL (HLA-A*2402 EBV LMP2) and RYLRDQQLLGI (HLA-A*2402 HIV envelop). PBMCs were stimulated with the EBV peptide in the presence of dendritic cells, and stained with Qdot-multimer or PEtetramer, and FITC-anti-CD8 antibody at room temperature. Results: EBV-Qdot-multimer was capable of detecting more EBV peptidespecific CD8+ T cells with high intensity than EBV-PE-tetramer. The peptide specificity of T cells was confirmed by using HIV-multimer or tetramer. Discussion: Our study indicated that Qdot-multimers were suitable for detecting peptide-specific CD8+ T cells with higher sensitivity than PE-tetramer. Qdot-multimers are now applied for the immunological monitoring in peptide vaccination therapy.