Prevention of early-onset familial/hereditary colon cancer: new models and mechanistic biomarkers (review).

Human colon cancer is a multi-factorial, multi-step disease wherein genetic and dietary factors represent important regulators of initiation, promotion and progression. While the etiology of sporadic colon cancer remains largely unidentified, familial adenomatous polyposis (FAP) and hereditary non-polyposis colon cancer (HNPCC) represent predisposing genetic syndromes for early-onset familial/hereditary colon cancer. These syndromes are characterized by germ-line mutations in the adenomatous polyposis coli (APC) and/or DNA mismatch repair genes, respectively. Currently available preclinical animal models for human FAP and HNPCC syndromes, expressing clinically relevant germ-line mutations, exhibit adenomas in the small intestine rather than in the colorectum. These models are, therefore, subject to extrapolation for direct clinical translatability of the data for colon carcinogenesis and chemoprevention. Experimental models expressing clinically relevant genetic defects (APC and/or DNA mismatch repair gene mutations) in an appropriate target site (colon) may represent novel approaches that reduce extrapolation of the data for their clinical relevance. This report provides an overview on carcinogenesis and chemoprevention in preclinical models of FAP and HNPCC syndromes, and summarizes recent data on i) development of new cell culture models for FAP and HNPCC syndromes; and ii) validation of developed models for rapid, mechanism-based screening of new pharmacological or naturally occurring chemopreventive agents.