Abstract IA018: Microbiome and intestinal barriers in colon cancer

Abstract

Abstract Multiple factors (e.g., risk genes, environmental triggers, immunity, and microbiome) contribute to the pathogenesis of colorectal cancer (CRC). The intestinal dysbiosis and disruption of barrier function are common manifestations of CRC. Vitamin D/Vitamin D receptor (VDR) is known to protects against dysbiosis and tumorigenesis. Considering the multiple functional roles of VDR in the development of cancer, it is important to dissect the mechanisms by which host factors contribute to the intestinal barrier function in protecting cells from tumorigenesis. Here, we reported that in human tissue, reduced VDR in the colon of CRC patients is associated with the reduced intestinal barrier and enhanced bacterial translocation to tumors. VDR deficiency in the intestinal epithelial cells led to the reduced thickness of mucus layer and enhanced penetration of microbiota into the epithelial cells. VDR was a transcriptional factor regulating the genes of some tight junction (TJ) Claudins. The positively correlated status of VDR and Claudins (e.g., Claudin- 5 and10) contribute to the altered intestinal permeability in tumorigenesis. In the intestinal epithelial VDR conditionally knockout VDR∆IEC mice and myeloid VDR deletion mice, dysbiosis and inflammatory cytokines in the VDR deficient context further altered TJ proteins and manipulated the barrier functions in the development of colon cancer. Furthermore, we found that mice with colonic adenomatous polyposis coli (APC) mutation reduced thickness of mucus layer and enhanced penetration of microbiota into the epithelial cells, thus enhancing tumorigenesis in the colon. Studies on host factor regulation of microbiome and barriers could be potentially applied to risk assessment, early detection, and prevention of colon cancer. These studies will provide an additional avenue to restore microbiome and barrier functions for risk assessment and prevention of CRC and other cancers. Citation Format: Jun Sun, Jilei Zhang, Yinglin Xia, Yong-Guo Zhang. Microbiome and intestinal barriers in colon cancer [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer; 2022 Oct 1-4; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_1):Abstract nr IA018.