Published papers

MicroRNAs (miRNAs/miRs) regulate the levels of transcripts and serve a critical function in the regulation of tumor microenvironments. Therefore, miRNA levels in cancer tissues are thought to be potential biomarkers for immunotherapy. From a phase I trial of a vaccine treatment using 5 human leukocyte antigen (HLA)-A* 2402-restricted peptides (registration no. UMIN000004948), colorectal cancer (CRC) tissues were obtained from 8 patients and normal colorectal tissues from 5 patients via surgery. From a phase II trial using the same peptides (registration no. UMIN000001791), CRC tissues were obtained from 16 patients from the HLA-A* 2402-matched group and 10 patients from the HLA-A* 2402-unmatched group. These tissues were used for miRNA microarray analysis. As the first step, cancer tissues from the phase I study were used and 10 candidate miRNAs were selected by comparing the miRNA expression between two groups one with improved prognosis and the other with poor prognosis. The miRNAs were subsequently validated using the cases enrolled in the phase II study. Significantly improved prognoses were identified in 16 patients in the HLA-A* 2402-matched group with high expression of miR-196b-5p and low expression of miR-378a-3p and miR-486-5p. There was no difference in prognosis in the 10 patients in the HLA-A* 2402-unmatched group. Therefore, high miR-196b expression and low miR-378a-3p and miR-486-5p expression were indicated as useful biomarkers for prediction of the efficacy of vaccine treatment for patients with metastatic CRC. In a planned phase III study, expression levels of these 3 miRNAs (miR-196b-5p, miR-378a-3p and miR-486-5p) may be useful biomarkers for assessing patients who are likely to have an improved outcome following vaccination.

The cancer-testis antigens (CTA) are a large family of tumor-associated antigens expressed by a variety of cancer cells and primitive germ cells of the adult testis and placenta. These tumor-restricted expressing patterns suggest that CTA would be ideal targets for tumor-specific immunotherapy. XAGE-1 is a CTA that was originally identified by computer-based screening, and four transcription variants, XAGE-1a, -1b, -1c and -1d, have been characterized to date. Although the presence of XAGE-1 transcripts has been reported in various cancers, the expression of XAGE-1b in melanoma has not been fully characterized. In this study, we performed immunohistochemical staining of XAGE-1b together with NY-ESO-1, a well-known CTA, in 113 melanoma samples obtained from 84 patients and evaluated their expression in tumor cells. The effects of expression on tumor progression and patient prognosis were analyzed. Both XAGE-1b and NY-ESO-1 were expressed at high levels in lymph node metastasis and skin metastasis samples compared with the primary site (P < 0.01 in XAGE-1b and P < 0.05 in NY-ESO-1). In a subgroup analysis of 22 patients with stage III lymph node metastasis, overall survival was significantly higher in the XAGE-1b and NY-ESO-1 double-negative group than in the other groups (P < 0.05). These results suggest that lack of XAGE-1b and NY-ESO-1 expression could have a positive influence on clinical outcome in patients with melanoma.

Chronic graft-versus-host disease (cGVHD) is a notorious complication of allogeneic hematopoietic stem cell transplantation and causes disabling systemic inflammation and fibrosis. In this novel study, we focused on a relationship between endoplasmic reticulum (ER) stress and cGVHD, and aimed to create effective treatment of cGVHD. A series of experiments were conducted using a mouse model of cGVHD. Our data suggested (1) that ER stress was elevated in organs affected by cGVHD and (2) that 4-phenylbutyric acid (PBA) could reduce cGVHD-induced ER stress and thereby alleviate systemic inflammation and fibrosis. Because fibroblasts are thought to be implicated in cGVHD-elicited fibrosis and because macrophages are reported to play a role in the development of cGVHD, we investigated cGVHD-triggered ER stress in fibroblasts and macrophages. Our investigation demonstrated (1) that indicators for ER stress and activation markers for fibroblasts were elevated in cGVHD-affected lacrimal gland fibroblasts and (2) that they could be reduced by PBA. Our work also indicated that splenic macrophages from PBA-dosed mice exhibited the lower levels of ER stress and M2 macrophage markers than those from cGVHD-affected mice. Collectively, this study suggests that the reduction of ER stress utilizing PBA can be a clinically translatable method to treat systemic cGVHD.