Abstract

Pooled RNAi Screens in Xenograft Mouse Models

Donato Tedesco, Lead Research Scientist, Cellecta Inc

RNAi loss-of-function screens with pooled shRNA expression libraries have proven to be a useful tool to identify essential cancer genes and drug resistance mechanisms in numerous cell lines in vitro. The effects of interfering shRNAs to large numbers of genes on cell growth and viability can be measured simultaneously using this approach. Now there is considerable interest to adapt this sort of RNAi screen to ex vivo xenograft 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 to constructing pooled shRNA libraries that enables proliferation measurements of clonal populations produced by the individual shRNA-expressing founder cells that produce the tumor. This capability 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 data using this approach.