滝本 哲也

The clinical significance of comprehensive genomic profiling (CGP) has been established in metastatic castration-resistant prostate cancer (PC). However, the role of genomic profiling in localized PC remains unclear. In this exploratory study, we evaluated somatic genomic alterations in localized PC using an in-house CGP platform to examine their associations with biochemical recurrence (BCR) and recurrence-free survival (RFS) after radical prostatectomy. DNA extracted from surgical specimens of 314 patients with localized PC was analyzed for alterations in 164 cancer-related genes. Six genes (PTEN, BRCA2, POLD1, ERBB3, MYC, and SETD2) were more frequently altered in patients who developed BCR in exploratory analyses. Patients harboring alterations in any of these genes (n = 96) showed higher pathological T stage, increased BCR rates (27.1% vs. 6.4%), and inferior RFS compared with alteration-negative patients (n = 218; p < 0.001). In multivariate analysis, the presence of these alterations was independently associated with worse RFS. Among individual genes, BRCA2 alteration, and particularly BRCA2-SETD2 co-alteration, were associated with unfavorable outcomes, although the latter finding was based on a limited number of cases. In patients who developed BCR, alterations were associated with shorter PSA doubling time and poorer outcomes after salvage radiotherapy, particularly in margin-negative cases; however, these subgroup analyses were based on small numbers and should be interpreted as hypothesis-generating. These findings suggest that somatic genomic alterations identified at prostatectomy are associated with early recurrence in localized PC. Further validation in independent cohorts is required to determine whether genomic profiling may contribute to future risk stratification and management strategies.

BACKGROUND: Esophageal squamous cell carcinoma(ESCC) often develops resistance to standard chemotherapy regimens of docetaxel/cisplatin/5-fluorouracil(DCF) therapy. Strategies to overcome chemoresistance remain a significant clinical challenge. METHODS: DCF-resistant ESCC cell lines were established in the beginning through long-term exposure to chemotherapeutic agents. Gene expression profiles were analyzed via RNA sequencing, and functional assays were conducted to evaluate the impact of various calcium channel blockers(CCBs) on cell viability. RESULTS: Transcriptomic analysis revealed enrichment of endoplasmic reticulum(ER) stress pathways in DCF-resistant ESCC cells. Among CCBs tested, combined therapy DCF with CCBs restored chemosensitivity. CONCLUSION: DCF-resistant ESCC cells were resensitized with combined therapy with DCF and CCBs by enhacing ER stress response. This may provide a potential rationale for repurposing CCBs as adjuvant agents in chemotherapy of ESCC.

Mitochondria are dynamic organelles that undergo continuous morphological changes, yet exhibit unique, cell-type-specific structures. In rod photoreceptor cells of the retina, these structures include elongated mitochondria in the inner segments and a distinct, large, circular mitochondrion in each presynaptic terminal. The mechanisms underlying the establishment and maintenance of these specialized mitochondrial morphologies, along with their functional significance, are not well understood. Here, we investigate the roles of mitochondrial fusion proteins mitofusin 1 (MFN1) and mitofusin 2 (MFN2) in shaping these structures and maintaining photoreceptor cell health. Rod photoreceptor cell-specific ablation of MFN1 and MFN2 resulted in mitochondrial fragmentation by one month of age, suggesting that mitochondrial fusion is essential for the development of photoreceptor cell-specific mitochondrial structures. Notably, the layer structures of the retina examined by light microscopy appeared unaffected at this age. Following this time period, significant photoreceptor cell degeneration occurred by three months of age. Furthermore, we showed that impaired mitochondrial fusion perturbed the balance of proteins involved in glycolysis, oxidative phosphorylation (OXPHOS), and β-oxidation, highlighting the critical role of mitochondrial fusion in ensuring the proper levels of proteins necessary for optimal energy metabolism. Additionally, we identified upregulation of cellular stress pathways such as endoplasmic reticulum (ER) stress and unfolded protein response (UPR), which arise in response to energy deprivation, and cytoprotective biosynthetic pathways mediated by CCAAT/enhancer-binding protein gamma (C/EBPγ) and mammalian target of rapamycin complex 1 (mTORC1) signaling. In summary, our findings indicate that mitochondrial fusion through MFN1 and MFN2 is vital for the development of unique mitochondrial structures and proper energy production, underscoring the fundamental importance of mitochondrial dynamics in photoreceptor cell function and survival.

Colorectal cancer (CRC) is well characterized in terms of genetic mutations and the mechanisms by which they contribute to carcinogenesis. Mutations in APC, TP53, and KRAS are common in CRC, indicating key roles for these genes in tumor development and progression. However, for certain tumors with low frequencies of these mutations that are defined by tumor location and molecular phenotypes, a carcinogenic mechanism dependent on BRAF mutations has been proposed. We here analyzed targeted sequence data linked to clinical information for CRC, focusing on tumors with a high tumor mutation burden (TMB) in order to identify the characteristics of associated mutations, their relations to clinical features, and the mechanisms of carcinogenesis in tumors lacking the major driver oncogenes. Analysis of overall mutation frequencies confirmed that APC, TP53, and KRAS mutations were the most prevalent in our cohort. Compared with other tumors, TMB-high tumors were more frequent on the right side of the colon, had lower KRAS and higher BRAF mutation frequencies as well as a higher microsatellite instability (MSI) score, and showed a greater contribution of a mutational signature associated with MSI. Ranking of variant allele frequencies to identify genes that play a role early in carcinogenesis suggested that mutations in genes related to the DNA damage response (such as ATM and POLE) and to MSI (such as MSH2 and MSH6) may precede BRAF mutations associated with activation of the serrated pathway in TMB-high tumors. Our results thus indicate that TMB-high tumors suggest that mutations of genes related to mismatch repair and the DNA damage response may contribute to activation of the serrated pathway in CRC.

BACKGROUND: Colorectal cancer (CRC) is a substantial global health concern due to its limited treatment options, especially for oxaliplatin (L-OHP) regimen resistance. This study used organoid-based screening methodologies to evaluate drug responses in CRC while validating the approach with patient-derived CRC organoids and investigating potential biomarkers. METHODS: Patient-derived organoids were created from CRC surgical specimens, and drug screening were performed. Selected organoids with high and low L-OHP sensitivity underwent next-generation sequencing (NGS), and in vivo experiments using xenotransplantation were used to validate in vitro results. Moreover, the clinical application of homologous recombination deficiency (HRD) as a biomarker was investigated. RESULTS: Organoid drug screening revealed differences in L-OHP sensitivity among 34 patient-derived CRC organoids, and NGS deemed HRD as a potential biomarker. In vivo experiments validated the correlation between HRD status and L-OHP sensitivity, and clinical data suggested the potential of HRD as a biomarker for recurrence-free survival in patients treated with L-OHP. Additionally, HRD exhibited potential as a biomarker for other platinum agents and poly (ADP-ribose) polymerase inhibitors in CRC. CONCLUSIONS: The study underscores HRD as a potential biomarker for predicting L-OHP sensitivity, expanding its application to other drugs in CRC. Organoid screening is reliable, providing insights into the intricate association between genetic features and treatment responses.