ALBERT

Description: Publication date: 20 November 2014 Source: Cell Reports, Volume 9, Issue 4 Author(s): Patricia A. Possik , Judith Müller , Carmen Gerlach , Juliana C.N. Kenski , Xinyao Huang , Aida Shahrabi , Oscar Krijgsman , Ji-Ying Song , Marjon A. Smit , Bram Gerritsen , Cor Lieftink , Kristel Kemper , Magali Michaut , Roderick L. Beijersbergen , Lodewyk Wessels , Ton N. Schumacher , Daniel S. Peeper To identify factors preferentially necessary for driving tumor expansion, we performed parallel in vitro and in vivo negative-selection short hairpin RNA (shRNA) screens. Melanoma cells harboring shRNAs targeting several DNA damage response (DDR) kinases had a greater selective disadvantage in vivo than in vitro, indicating an essential contribution of these factors during tumor expansion. In growing tumors, DDR kinases were activated following hypoxia. Correspondingly, depletion or pharmacologic inhibition of DDR kinases was toxic to melanoma cells, including those that were resistant to BRAF inhibitor, and this could be enhanced by angiogenesis blockade. These results reveal that hypoxia sensitizes melanomas to targeted inhibition of the DDR and illustrate the utility of in vivo shRNA dropout screens for the identification of pharmacologically tractable targets. Graphical abstract Teaser Specific parameters lacking in vitro, but present in vivo, influence tumor behavior and therapeutic dependencies. Possik et al. now perform parallel in vitro and in vivo negative-selection screens and uncover a critical requirement for DNA damage response kinases in expanding tumors, a liability that could be exploited pharmacologically.