Abstract 5023: Stem cell hypothesis and function of Lgr5 in the development of colon cancer.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Similar to normal colonic epithelium, colorectal carcinomas (CRC) comprise subpopulations of cells with stem-like properties. Leucine-rich-repeat-containing G-protein-coupled receptor 5 (Lgr5) is associated with these stem cells in normal colonic epithelium and CRC. Here, we analyzed the functional and molecular consequences of shRNA-mediated silencing of Lgr5 in CRC cell lines SW480 and HT-29. Additionally, we exposed Lgr5-EGFP-IRES-Cre-ERT2 mice to azoxymethane/dextrane sodium sulfate (AOM/DSS) which induces inflammation-driven colon tumors. Tumors were then flow-sorted into Lgr5 high and low epithelial cell fractions and molecularly characterized using gene expression profiling and array comparative genomic hybridization. Silencing of Lgr5 in SW480 cells resulted in a depletion of the spheroid cell fraction, yet did not affect the adherently growing cell population. It also reduced proliferation, migration, and colony formation in vitro as well as tumorigenicity in vivo, consistent with a down-regulation of Notch signaling. Spheroid cells were enriched for several stem cell-associated genes including Lgr5. Lgr5 high cells of AOM/DSS-induced mouse colon tumors displayed higher Wnt signaling compared to both their Lgr5 low tumor cell counterparts as well as Lgr5 high normal colon stem cells. Lgr5 high and low tumor cells were both chromosomally stable. In conclusion, our data suggest Lgr5 as a functionally important marker for stem-like cells in CRC, representing a potential therapeutic target. Citation Format: Daniela D. Hirsch, Nick Barker, Nicole McNeil, Yue Hu, Jordi Camps, Katherine McKinnon, Hans Clevers, Thomas Ried, Timo Gaiser. Stem cell hypothesis and function of Lgr5 in the development of colon cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5023. doi:10.1158/1538-7445.AM2013-5023