Chronic inflammation and, specifically, infection-associated inflammatory processes, enhance carcinogenesis in the affected organs. Chronic innate immune responses are known to contribute to these processes whereas the contributions of adaptive immunity to carcinogenesis are less clear. We have identified a human colon anaerobic bacterium, enterotoxigenic Bacteroides fragilis (ETBF), that induces a rapid and dramatic increase in colon tumors in multiple intestinal neoplasia mice (MinApc). This model replicates features of human colorectal cancer and our data demonstrate that colon tumorigenesis in this system is dependent, in part, on a novel Stat3/Th17 pathway, thereby defining a distinct role for adaptive immunity in colon cancer pathogenesis. Herein we seek to further define the mechanisms by which Stat3 activation in distinct cellular compartments and the resultant components of the Th17 response crosstalk with the colonic epithelium, inducing genetic and/or epigenetic epithelial cell changes that result in colon tumorigenesis. Our studies will begin to identify links between specific inflammatory mediators and the genetic changes critical to colon carcinogenesis. This work has direct relevance to the design of studies to investigate the pathogenesis of human colorectal cancer and may have implications for novel approaches to colorectal cancer therapy. Colorectal cancer is a major public health problem being the second leading cause of cancer death in the United States in women and men.

Public Health Relevance

Colon cancer is the second leading cause of cancer death for women and men. The microbial and immunologic mechanisms contributing to colon cancer are unknown. This project will study the immune and genetic mechanisms by which a newly recognized common human stool bacterium called enterotoxigenic Bacteroides fragilis (ETBF) triggers colon tumors in mice, providing new insights into how colon cancer developes and potentially new approaches to colon cancer therapy.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Gastrointestinal Mucosal Pathobiology Study Section (GMPB)
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Daschner, Phillip J
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Johns Hopkins University
Internal Medicine/Medicine
Schools of Medicine
United States
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Maiuri, Ashley R; Peng, Michael; Sriramkumar, Shruthi et al. (2017) Mismatch Repair Proteins Initiate Epigenetic Alterations during Inflammation-Driven Tumorigenesis. Cancer Res 77:3467-3478
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Housseau, Franck; Wu, Shaoguang; Wick, Elizabeth C et al. (2016) Redundant Innate and Adaptive Sources of IL17 Production Drive Colon Tumorigenesis. Cancer Res 76:2115-24
Geis, Abby L; Housseau, Franck (2016) Procarcinogenic regulatory T cells in microbial-induced colon cancer. Oncoimmunology 5:e1118601
DeStefano Shields, Christina E; Van Meerbeke, Sara W; Housseau, Franck et al. (2016) Reduction of Murine Colon Tumorigenesis Driven by Enterotoxigenic Bacteroides fragilis Using Cefoxitin Treatment. J Infect Dis 214:122-9
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Geis, Abby L; Fan, Hongni; Wu, Xinqun et al. (2015) Regulatory T-cell Response to Enterotoxigenic Bacteroides fragilis Colonization Triggers IL17-Dependent Colon Carcinogenesis. Cancer Discov 5:1098-109
Sears, Cynthia L; Geis, Abby L; Housseau, Franck (2014) Bacteroides fragilis subverts mucosal biology: from symbiont to colon carcinogenesis. J Clin Invest 124:4166-72
McAllister, Florencia; Housseau, Franck; Sears, Cynthia L (2014) Microbiota and immune responses in colon cancer: more to learn. Cancer J 20:232-6

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