稲村 健太郎

Colibactin, a genotoxin produced by Escherichia coli strains harboring the polyketide synthetase (pks) gene cluster, causes DNA damage and somatic mutations. pks+E. coli is enriched in primary colorectal cancer (CRC) and is associated with clonal driver mutations, but its role in CRC liver metastasis is unclear. We assessed the association of pks+ E. coli in CRC liver metastasis tissues with systemic and local immune responses and the number of organs involved in recurrence using specimens and clinicopathological data from 239 patients with CRC liver metastasis who underwent metastasectomy. The levels of pks+E. coli in fresh-frozen specimens were quantified as "very low" (<50th percentile), "low" (50th to 75th percentiles), and "high" (>75th percentile) using a digital PCR. Immunohistochemical analysis of tumor-infiltrating immune cells was performed using tissue microarrays. Systemic inflammation was evaluated using serum C-reactive protein (CRP) levels. pks+E. coli was detected in 66.7% (157 of 239) liver metastasis tissues. Higher levels of pks+E. coli were associated with decreased serum CRP levels and reduced densities of CD4+ cells and CD163+ cells in the tumor-immune microenvironment. The "high" pks+ E. coli group had fewer metastatic organs involved than the "very low" pks+ E. coli group (mean number of organs: 1.00 vs. 1.23). These findings suggest that pks+E. coli play a modulating role in CRC metastasis.

The presence of Fusobacterium nucleatum is associated with an immunosuppressive tumor immune microenvironment (TIM) in primary colorectal cancer (CRC), contributing to tumor progression. Its persistence in CRC liver metastasis tissues raises questions about its role in modulating local and systemic immune responses and influencing recurrence patterns. This retrospective cohort study of 218 patients with CRC liver metastasis investigated the association of F. nucleatum in CRC liver metastasis tissues with systemic inflammation, TIM alterations, and the number of metastatic organs involved in recurrence. Two-step polymerase chain reaction (PCR), including digital PCR, detected F. nucleatum in 42% (92/218) of fresh-frozen specimens of CRC liver metastases. Compared with the F. nucleatum-none group, the F. nucleatum-high group showed higher C-reactive protein levels (0.82 vs. 0.22 mg/dL; Ptrend = 0.02), lower numbers of CD8+ cells (33.2 vs. 65.3 cells/mm2; Ptrend = 0.04) and FOXP3+ cells (11.3 vs. 21.7 cells/mm2; Ptrend = 0.01) in the TIM, and a greater number of metastatic organs involved in recurrence (1.6 vs. 1.1; p < 0.001). The presence of F. nucleatum in CRC liver metastasis tissues was associated with increased systemic inflammation, TIM alterations, and a greater number of metastatic organs involved in recurrence. These findings suggest a potential contribution of F. nucleatum to the metastatic propensity of CRC cells and could inform future research to enhance understanding of the interaction between tumor, host, and microbes in the metastatic process.

Inverted urothelial papilloma (IUP) is a benign neoplasm characterized by a downgrowth of the urothelium beneath the surface of morphologically normal urothelial cells; however, the molecular features of IUP and their association with clinicopathological characteristics are unclear. In this study, we aimed to investigate the mutational landscape, clinicopathological features, genotype-phenotype associations, and spread patterns of IUP. We performed targeted next-generation sequencing of 39 consecutive IUP cases, the largest series investigated to date, and identified oncogenic driver mutations in RAS family genes in 34 cases (87%). HRAS mutations were the most prevalent (28 cases), which included Q61R (15 cases), followed by KRAS (5 cases) and NRAS (1 case) mutations. Characteristic mutations observed in urothelial carcinoma, including those in FGFR3, TP53, or the TERT promoter, were absent. HRAS-mutated IUPs were associated with a history of smoking (P = 0.017) and streaming morphology (P < 0.001), corresponding to the trabecular subtype. In contrast, all KRAS-mutated IUPs occurred in never-smoking patients (P = 0.001) and showed cystic changes in morphology (P = 0.005), corresponding to the glandular subtype. RAS Q61R immunohistochemistry visually revealed the neoplastic nature of the overlying cells and distinct spread patterns of IUP cells within the surface, including pseudoinfiltrative spread. No recurrence or carcinoma development was observed in any of the IUP cases during the follow-up period. Thus, we confirmed the importance of RAS pathway activation in IUP pathogenesis, an association between RAS family gene mutations and IUP subtypes, and the spread patterns of IUP cells within the surface.

Hepatocellular carcinomas (HCCs) with biliary/progenitor cell features frequently show increased programmed death-ligand 1 (PD-L1) expression, but their response to immunotherapy is not high. One possible explanation for this phenomenon could be the loss of major histocompatibility complex (MHC) class I expression on tumor cells, which impairs the presentation of tumor antigens to cytotoxic T cells. However, the potential correlation between MHC class I loss, biliary/progenitor cell features, and the tumor-immune microenvironment remains largely unexplored. Herein, we hypothesized that MHC class I loss could be associated with biliary/progenitor cell features and potentially impact the tumor-immune microenvironment. To evaluate this hypothesis and gain insight into the characteristics of tumor cells and the tumor-immune microenvironment in HCCs with MHC class I loss, we examined a consecutive series of 397 HCC cases. MHC class I loss was observed in 32 HCCs (8.1%). Lipid-less cytologic morphology was significantly associated with MHC class I loss (P = 0.02). CK19 expression and decreased ARG1 expression, both known as biliary/progenitor cell features, were significantly associated with MHC class I loss (P < 0.05). PD-L1 expression was irrelevant to the MHC class I status. HCCs with MHC class I loss exhibited significantly lower infiltration of CD8+, CD4+, CD20+, and FOXP3+ cells than those with intact MHC class I (all Ps < 0.01). Our study reveals an association between MHC class I loss, biliary/progenitor cell features, and a "cold" tumor-immune microenvironment in HCCs. These insights highlight the potential impact of MHC class I loss on tumor cells and the tumor-immune microenvironment.

The microbiota is widely recognized to influence diverse biological processes, including metabolism, neurological and cardiovascular functions, the inflammatory response and immunity [...].

Cancer is generally regarded as a localised disease, with the well-established role of the tumour microenvironment. However, the realm of cancer goes beyond the tumour microenvironment, and cancer should also be regarded as a systemic and environmental disease. The exposome (ie, the totality of exposures), which encompasses diets, supplements, smoking, alcohol, other lifestyle factors, medications, etc, likely alters the microbiome (inclusive of bacteria, viruses, archaea, fungi, parasites, etc) and immune system in various body sites and influences tumour phenotypes. The systemic metabolic/inflammatory status, which is likely influenced by exposures and intestinal physiological changes, may affect tissue microenvironment of colorectum and any other organs. Germline genomic factors can modify disease phenotypes via gene-by-environment interactions. Although challenges exist, it is crucial to advance not only basic experimental research that can analyse the effects of exposures, microorganisms and microenvironmental components on tumour evolution but also interdisciplinary human population research that can dissect the complex pathogenic roles of the exposome, microbiome and immunome. Metagenomic, metatranscriptomic and metabolomic analyses should be integrated into well-designed population research combined with advanced methodologies of artificial intelligence and molecular pathological epidemiology. Ideally, a prospective cohort study design that enables biospecimen (such as stool) collection before disease detection should be considered to address reverse causation and recall biases. Robust experimental and observational research together can provide insights into dynamic interactions between environmental exposures, microbiota, tumour and immunity during carcinogenesis processes, thereby helping us develop precision prevention and therapeutic strategies to ultimately reduce the cancer burden.

The microbiota influences human health and the development of diverse diseases, including cancer. Microbes can influence tumor initiation and development in either a positive or negative manner. In addition, the composition of the gut microbiota affects the efficacy and toxicity of cancer therapeutics as well as therapeutic resistance. The striking impact of microbiota on oncogenesis and cancer therapy provides compelling evidence to support the notion that manipulating microbial networks represents a promising strategy for treating and preventing cancer. Specific microbes or the microbial ecosystem can be modified via a multiplicity of processes, and therapeutic methods and approaches have been evolving. Microbial manipulation can be applied as an adjunct to traditional cancer therapies such as chemotherapy and immunotherapy. Furthermore, this approach displays great promise as a stand-alone therapy following the failure of standard therapy. Moreover, such strategies may also benefit patients by avoiding the emergence of toxic side effects that result in treatment discontinuation. A better understanding of the host-microbial ecosystem in patients with cancer, together with the development of methodologies for manipulating the microbiome, will help expand the frontiers of precision cancer therapeutics, thereby improving patient care. This review discusses the roles of the microbiota in oncogenesis and cancer therapy, with a focus on efforts to harness the microbiota to fight cancer.

BACKGROUND: Prostate cancer spans a broad spectrum from indolent to deadly disease. In the management of prostate cancer, diagnostic biopsy specimens are important sources of data that inform the selection of treatment. B7-H3 (CD276), an immune checkpoint molecule, has emerged as a promising immunotherapy target. B7-H3 expression is related to adverse clinical outcomes in various types of cancer; however, little is known concerning the association between tumor B7-H3 expression in diagnostic biopsy specimens and clinical outcome in patients with metastatic prostate cancer. METHODS: We evaluated tumor B7-H3 expression levels in diagnostic biopsy specimens from 135 patients with metastatic prostate cancer and 113 patients with localized prostate cancer. RESULTS: High B7-H3 expression was more frequently observed in patients with metastatic cancer than in those with localized cancer (31 vs. 12%; p = 0.0003). In patients with localized cancer, the B7-H3 expression status was not associated with biochemical recurrence-free survival. However, among patients with metastatic cancer, high B7-H3 expression was independently associated with high disease-specific mortality (multivariable hazard ratio [HR] = 2.72; p = 0.047) and overall mortality rates (multivariable HR = 2.04; p = 0.025). CONCLUSIONS: Tumor B7-H3 expression in diagnostic biopsy specimens may be a useful biomarker for identifying highly aggressive metastatic prostate cancer. Given the potential utility of anti-B7-H3 immunotherapy, this information may aid in stratifying prostate cancer based on its responsiveness to B7-H3-targeted treatment.

Immunotherapy, which shows great promise for treating patients with metastatic malignancies, has dramatically changed the therapeutic landscape of cancer, particularly subsequent to the discovery of immune checkpoint inhibitors. However, the responses to immunotherapy are heterogeneous and often transient. More problematic is that a high proportion of patients with cancer are resistant to such therapy. Much effort has been expended to identify reliable biomarkers that accurately predict clinical responses to immunotherapy. Unfortunately, such tools are lacking, and our knowledge of the mechanisms underlying its efficacy and safety is insufficient. The microbiota is increasingly recognized for its influence on human health and disease. Microbes create a pro- or an anti-inflammatory environment through complex interactions with host cells and cytokines. Emerging evidence indicates that microbes alter the efficacy and toxicity of immunotherapy by modulating the host's local and systemic immune responses. It is therefore critically important to exploit the microbiota to develop biomarkers as well as to identify therapeutic targets that can be applied to cancer immunotherapy. This review provides insights into the challenges that must be addressed to achieve these goals.

Background: B7-H3 (CD276), an immune checkpoint molecule, regulates the tumor-immune microenvironment and controls the aggressiveness of various tumors. Although B7-H3 expression has been associated with the number of tumor-infiltrating FOXP3+ regulatory T cells, little information is available about this association in clear cell renal cell carcinoma (ccRCC). Methods: Using 252 consecutive cases of ccRCC, we examined the association of B7-H3 expression in both the tumor cells and tumor vasculature with the number of tumor-infiltrating FOXP3+ cells and assessed whether the effects of B7-H3 expression on survival differ according to FOXP3+ cell number. Results: High B7-H3 expression was observed in the tumor cells and tumor vasculature in 15% and 54% of ccRCC cases, respectively. High FOXP3+ cell number was positively associated with B7-H3 expression in both the tumor cells (odds ratio [OR] =2.93; P=0.0041) and tumor vasculature (OR=2.45; P=0.0007). Tumor cell B7-H3 expression was associated with increased disease-specific mortality in high FOXP3+ cell number group (hazard ratio [HR] =2.98; P=0.017), but not in low FOXP3+ group (P=0.71). Tumor vasculature B7-H3 expression was also associated with increased disease-specific mortality in high FOXP3+ cell number group (HR=4.86; P=0.0025), but not in low FOXP3+ group (P=0.48). Conclusion: We demonstrate that B7-H3 expression in both tumor cells and the tumor vasculature is positively associated with FOXP3+ cell number. Such expression is also associated with increased mortality in high FOXP3+ cell number group, but not in low FOXP3+ cell number group. These findings suggest that B7-H3-expressing ccRCCs may exert tumor-promoting immunity by interacting with FOXP3+ regulatory T cells in the tumor microenvironment.