Abstract 1721: Moving beyondin vitromodels and addressing the challenges of pooled RNAi screens in mouse xenografts

RNAi loss-of-function screening with pooled shRNA expression libraries has proven to be a useful tool to identify essential cancer genes and drug resistance mechanisms in numerous cell lines in vitro. The effects of knocking down large numbers of genes on cancer cell growth and viability can be measured simultaneously using this approach. Now there is considerable interest to adapt RNAi viability screens to ex vivo xenograft mouse models. However, small take rates, growth rate variance of cells, and differing cell microenvironments in these more complex tumor models impose significant challenges to this sort of assay. We have developed a novel approach based on the use of pooled shRNA libraries with clonal barcodes that enables proliferation measurements of clonal populations produced by the individual shRNA-expressing founder cells that produce the tumor. This RNAi clonal analysis provides a basis to separate, across large cell populations, the external parameters that strongly influence cell growth rates from shRNA-induced growth inhibition in these systems. We will present in vivo RNAi screening validation data for several cancer models. Citation Format: Donato Tedesco, Kyle Bonneau, Mikhail Makhanov, Debbie Deng, Paul Diehl, Peiqing Sun, Alex Chenchik. Moving beyond in vitro models and addressing the challenges of pooled RNAi screens in mouse xenografts. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4266. doi:10.1158/1538-7445.AM2014-4266