Abstract A36: Characterizing the role of Egfr signaling in mediating the exacerbative effect of acute inflammation on tumor development in a mouse model for familial adenomatous polyposis

Over the past decade a number of inducible mouse models of intestinal tumor formation have been developed to study the genetic and cellular changes that contribute to colorectal cancer (CRC) development. Among them, the Lrig1-Cre/+;Apcfl/+ mice serve as a good model to study familial adenomatous polyposis (FAP), as the targeted elimination of one copy of the Apc gene in the Lrig1-expressing (Lrig1+) intestinal progenitor cells leads to loss of heterozygosity of the remaining wild-type Apc allele in the intestinal epithelium and eventually the formation of multiple histologically advanced adenomas in the distal colon. However, adenomas formed in the Lrig1-Cre/+;Apcfl/+ mice do not progress to adenocarcinomas. In order to develop a mouse model that recapitulates the process of CRC development in its entirety, we treated the Lrig1-Cre/+;Apcfl/+ mice with the proinflammatory reagent dextran sodium sulfate (DSS) and found that a single cycle of DSS right after tamoxifen-induced initial loss of one Apc allele significantly exacerbated tumor formation in the distal colon. Interestingly, DSS-treated Lrig1-Cre/+;Apcfl/+ mice also developed highly dysplastic tumors in the proximal colon, which is normally spared from tumor formation in the untreated Lrig1-Cre/+;Apcfl/+ mice. Using a newly developed chimeric Egfr protein reporter mouse, we are interrogating the roles of dysregulated epithelial and stromal Egfr signaling in promoting tumor development in the DSS-treated Lrig1-Cre/+;Apcfl/+;EgfrEmGFP/+ mice. Citation Format: Wei Li, Yu-Ping Yang, Robert J. Coffey, Jr. Characterizing the role of Egfr signaling in mediating the exacerbative effect of acute inflammation on tumor development in a mouse model for familial adenomatous polyposis [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr A36.