MOLECULAR FEATURES AND MOUSE MODELS OF COLORECTAL CANCER.

Colorectal cancers (CRCs) harbor accumulated defects in key signaling pathways that regulate cell phenotypes, including proliferation, survival, metabolism, and differentiation. To study the functional contributions of the accumulated molecular defects in CRC, we have developed approaches to inactivate selected tumor suppressor and/or activate oncogenes in mouse colon epithelium. Conditional inactivation of the CDX2 tumor suppressor protein in conjunction with oncogenic activation of the BRAF protein promotes development of serrated glandular benign and malignant tumors in the mouse colon. The mouse tumors share significant morphological and molecular relationships with the 8% to 10% of human CRCs that manifest serrated morphology at diagnosis. The gene and protein expression patterns in the mouse tumors have informed understanding of the relationships between benign and malignant human serrated colon tumors. Our findings are consistent with prior work suggesting that perhaps upwards of one-third of human CRCs may arise from a precursor lesion with serrated morphology rather than a conventional adenoma.