Abstract 2859: Identification of driver mutations in colon cancer using Sleeping Beauty mutagenesis

Abstract

Abstract Human colon tumors contain hundreds of genetic and epigenetic anomalies, of which only a handful are responsible for the growth and development of the tumor. We have developed a forward genetic screen in mice that can identify those mutations capable of causing gastrointestinal tract tumors. By comparing the mutations identified in our screen with those found in human colon tumors we can pinpoint the drivers of carcinogenesis. The forward genetic screen uses the Sleeping Beauty (SB) DNA transposon as a random mutagen capable of both activating and inactivating genes. Using Cre recombinase under the control of the Villin promoter we can selectively activate this mutagenesis in intestinal epithelial cells in the mouse. Tumors generated in these mice are analyzed for transposon insertion sites using linker mediated-PCR in combination with high-throughput sequencing. This analysis provides us with genomic sequence that can be mapped to the mouse genome. Candidate cancer driver genes are identified because they are located in areas of the genome that are recurrently mutated by the SB transposon in multiple tumors. We conducted the screen in wild-type mice and identified 77 candidate cancer genes, of which six were previously known human colon cancer genes (APC, BMPR1A, SMAD4, PTEN, FBXW7, CDK8). More importantly, we identified many novel candidate drivers that can now serve as potential targets in colon cancer therapy. We have extended our studies by conducting three more screens using mice that already contain a known driver mutation. The purpose of these new screens is to gain a better understanding of the genetic changes that cooperate with common mutations found in colon cancer. The three screens used mice that have a mutation in Apc (ApcMin), carry a dominant negative acting Trp53 (p53R270H), or are null for the tumor suppressor gene p19ARF. We have completed the screen in ApcMin mice and found an additional 30 candidate drivers of colon cancer that may specifically cooperate with the Apc mutation. The two final screens are in the process of completion and should uncover genes that cooperate with mutations in Trp53 and p19ARF. The results of these studies will greatly expand the list of potential therapeutic targets and will enhance our understanding of the genetic etiology of colon cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2859. doi:10.1158/1538-7445.AM2011-2859