Zervantonakis, IoannisIavarone, ClaudiaChen, Hsing-YuSelfors, LauraPalakurthi, SangeethaLiu, Joyce F.Drapkin, RonnyMatulonis, UrsulaLeverson, Joel D.Sampath, DeepakMills, Gordon B.Brugge, Joan2017-12-052017Zervantonakis, I. K., C. Iavarone, H. Chen, L. M. Selfors, S. Palakurthi, J. F. Liu, R. Drapkin, et al. 2017. “Systems analysis of apoptotic priming in ovarian cancer identifies vulnerabilities and predictors of drug response.” Nature Communications 8 (1): 365. doi:10.1038/s41467-017-00263-7. http://dx.doi.org/10.1038/s41467-017-00263-7.http://nrs.harvard.edu/urn-3:HUL.InstRepos:34491986The lack of effective chemotherapies for high-grade serous ovarian cancers (HGS-OvCa) has motivated a search for alternative treatment strategies. Here, we present an unbiased systems-approach to interrogate a panel of 14 well-annotated HGS-OvCa patient-derived xenografts for sensitivity to PI3K and PI3K/mTOR inhibitors and uncover cell death vulnerabilities. Proteomic analysis reveals that PI3K/mTOR inhibition in HGS-OvCa patient-derived xenografts induces both pro-apoptotic and anti-apoptotic signaling responses that limit cell killing, but also primes cells for inhibitors of anti-apoptotic proteins. In-depth quantitative analysis of BCL-2 family proteins and other apoptotic regulators, together with computational modeling and selective anti-apoptotic protein inhibitors, uncovers new mechanistic details about apoptotic regulators that are predictive of drug sensitivity (BIM, caspase-3, BCL-XL) and resistance (MCL-1, XIAP). Our systems-approach presents a strategy for systematic analysis of the mechanisms that limit effective tumor cell killing and the identification of apoptotic vulnerabilities to overcome drug resistance in ovarian and other cancers.en-USJournal Article2017-12-0510.1038/s41467-017-00263-7