There is great interest currently in the role of survivin, a member of the inhibitors of apoptosis protein (lAP) family, in promoting colorectal tumorigenesis since survivin is markedly overexpressed in colonic cancer cells. The main aim of this research application is to demonstrate the inhibition of the expression and activity of survivin as a valid chemopreventive approach to colon carcinogenesis. To this end we will use the following mouse models of human intestinal and colon carcinogenesis: (i) The Apc Min/+ mouse in which the Apc gene has been inactivated by germ line chemical mutagenesis, (ii) Apc Min/+ mice deficient in surviving produced by cross-breeding with survivin +/- knockout mice, and (iii) mice treated with azoxymethane (AOM), a potent colonic pro-carcinogen. The mice will be fed standard AIN-93 A diet supplemented with flavopiridol, which is a flavone derivative that interferes with survivin's biological actions both at transcriptional and post-transcriptional levels. Sibling mice fed AIN-93A diet devoid of flavopiridol will serve as controls. The effectiveness of flavopiridol treatment in suppressing survivin activity and expression in mouse intestinal and colonic epithelial cells and in inhibiting intestinal and colon cancer development and progression, will be assessed by (i) microPET imaging of mice to monitor tumors development and progression in vivo, (ii) gross microscopic and determination of intestinal and colonic tumor number, distribution, size and histopathological categories, (iii) analysis of the apoptotic process using histological criteria and assessment of caspases 3 and 9 activity and (iv) in-depth examination of survivin expression and phosphorylation in intestinal and colonic tissues.
