Abstract LB-207: Dissecting the functional landscape of triple-negative breast cancer

Triple negative breast cancer (TNBC) is the most aggressive form of breast cancer with poor patient prognosis. Patients who respond poorly to the current standard of care cytotoxic chemotherapeutic regimens only have about a 55% five-year survival rate due to the lack of other effective TNBC therapeutics. To uncover new therapeutic entry points for TNBC, we employed a pangenomic loss of function siRNA screening approach. To account for heterogeneity within the patient population, we screened 4 triple negative tumor-derived breast cancer cell lines that represent the spectrum of oncogenic aberrations and molecular subtypes in TNBC. By intersecting the datasets from these 4 cell lines, we revealed core modulators of viability and chemotherapy-induced cellular stress that have not been previously implicated in TNBC biology. For example, our screen uncovered a tractable energy-sensing AMPK family member that supports tumor cell viability in a subset of TNBC tumors. We also discovered tumor cell vulnerabilities unique to the Basal-Like and Claudin-Low TNBC molecular subtypes. In particular, Basal-Like tumor cell division is sensitive to perturbations in specific cytokine signaling. With respect to Claudin-Lows, we found an increased sensitivity to depletion of transcriptional modulators and downstream targets of TGFβ signaling, which suggests that TGFβ signaling may not only be required for a mesenchymal phenotype but also for Claudin-Low tumor cell survival. Our findings suggest that a set of tumor cell vulnerabilities can partition TNBC into functional subgroups and these vulnerabilities could lead to new therapeutics improving overall TNBC patient prognosis. Citation Format: Kimberly Maxfield, Aleix Prat, Kathleen Corcoran, Angelique Whitehurst. Dissecting the functional landscape of triple-negative breast 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 LB-207. doi:10.1158/1538-7445.AM2013-LB-207