Biology subjects

Okagawa, T.

Publications and source records attributed to Okagawa, T..

3 recordsLinked to original sources

bioRxiv2024

Effect of C-to-T transition at CpG sites on tumor suppressor genes in tumor development in cattle evaluated by somatic mutation analysis in enzootic bovine leukosis

Oncogenic transformation of normal cells is caused by mutations and chromosomal abnormalities in cancer-related genes. Enzootic bovine leukosis (EBL) is a malignant B-cell lymphoma caused by bovine leukemia virus (BLV) infection in cattle. Although a small fraction of BLV-infected cattle develops EBL after a long latent period, the mechanisms for oncogenesis in EBL cattle remain largely unknown. In this study, we analyzed the types and patterns of somatic mutations in cancer cells from 36 EBL cases, targeting 21 cancer-related genes. Various somatic mutations were identified in 8 genes, TP53, NOTCH1, KMT2D, CREBBP, KRAS, PTEN, CARD11, and MYD88. In addition, TP53 gene was found to be mutated in 69.4% of EBL cases, with most being biallelic mutations. In some cases, associations were observed between the ages at which cattle had developed EBL and somatic mutation patterns; young onset of EBL possibly occurs due to congenital mutations, high impact mutations affecting protein translation, and biallelic mutations. Furthermore, nucleotide substitution patterns indicated that cytosine at CpG sites tended to be converted to thymine in many EBL cases, which was considered to be the result of spontaneous deamination of 5-methylctosine. These results demonstrate how somatic mutations have occurred in cancer cells leading to EBL development, thereby explaining its pathogenic mechanism. These findings will contribute to a better understanding and future elucidation of disease progression in BLV infection. ImportanceEnzootic bovine leukosis (EBL) is a malignant and lethal disease in cattle. Currently, there are no effective vaccines or therapeutic methods against bovine leukemia virus (BLV) infection, resulting in severe economic losses in livestock industry. This study provides a renewed hypothesis to explain the general mechanisms of EBL onset by combining the previous finding that several integration sites of BLV provirus can affect the increase in survival and proliferation of infected cells. We demonstrate that two additional random events are necessary for oncogenic transformation in infected cell clones, elucidating the reason why only few infected cattle develop EBL. Further exploration of somatic mutation and BLV integration sites could support this hypothesis more firmly, potentially contributing to the development of novel control methods for EBL onset.

cancer biology↗

bioRxiv2022

Diagnosis and early prediction of lymphoma using high-throughput clonality analysis of bovine leukemia virus-infected cells

Bovine leukemia virus (BLV), a retrovirus, infects into B cells of ruminants and causes aggressive leukemia or lymphoma in cattle, enzootic bovine leukosis (EBL). Clonal expansion of BLV-infected cells is a promising marker for early detection and diagnosis of EBL. Recently, we developed rapid amplification of the integration site without interference by genomic DNA contamination (RAISING) and CLOVA, a software to analyze clonality. RAISING-CLOVA could assess the risk of adult T-cell leukemia/lymphoma development in human T-cell leukemia virus-I-infected individuals through its clonality analysis. Thus, we herein examined the performance of RAISING-CLOVA for the clonality analysis of BLV-infected cells and conducted a comprehensive clonality analysis by RAISING-CLOVA in EBL and non-EBL cattle. RAISING-CLOVA successfully distinguished EBL from non-EBL cattle with high sensitivity and specificity. A longitudinal clonality analysis in BLV-infected sheep, an EBL model, also confirmed the effectiveness of BLV clonality analysis with RAISING-CLOVA for early detection of EBL development. Therefore, our study emphasizes the usefulness of RAISING-CLOVA as a routine clinical test for monitoring virus-related cancers.

microbiology↗

bioRxiv2020

PD-L1 expression in equine malignant melanoma and functional effects of PD-L1 blockade

Programmed death-1 (PD-1) is an immunoinhibitory receptor expressed on exhausted T cells during chronic illness. Interaction of PD-1 with its ligand PD-ligand 1 (PD-L1) delivers inhibitory signals and impairs proliferation, cytokine production, and cytotoxicity of T cells. We reported that the PD-1/PD-L1 pathway is closely associated with T-cell exhaustion and disease progression in bovine chronic infections and canine tumors. Moreover, we found that blocking antibodies targeting PD-1 and PD-L1 restore T-cell functions and may be used in immunotherapy in cattle and dogs. However, the immunological role of the PD-1/PD-L1 pathway remains unclear for chronic equine diseases, including tumors. In this study, we identified nucleotide sequences of equine PD-1 (EqPD-1) and PD-L1 (EqPD-L1) and investigated the role of anti-bovine PD-L1 monoclonal antibodies (mAbs) against EqPD-L1 using in vitro assays. We also evaluated the expression of PD-L1 in tumor tissues of equine malignant melanoma (EMM). The amino acid sequences of EqPD-1 and EqPD-L1 share a high identity and similarity with homologs from other mammalian species. Two clones of the anti-bovine PD-L1 mAbs recognized EqPD-L1 in flow cytometry, and one of these cross-reactive mAbs blocked the binding of equine PD-1/PD-L1. Importantly, PD-L1 expression was confirmed in EMM tumor tissues by immunohistochemistry. A cultivation assay revealed that PD-L1 blockade enhanced the production of Th1 cytokines in equine immune cells. These results suggest that our anti-PD-L1 mAbs may be useful for investigating the expression and role of the equine PD-1/PD-L1 pathway. Further research is required to discover the immunological role of PD-1/PD-L1 in chronic equine diseases and elucidate a future application in immunotherapy for horse.

immunology↗