Abstract A65: Evaluating an under-studied kinase as a potential druggable target for breast cancer

Abstract

Breast cancer is the most frequently diagnosed cancer among women, accounting for 23% of all cancer cases. Triple-negative breast cancer (TNBC) is a very aggressive type of breast cancer that occurs in African-American women at three-fold higher frequency compared to Hispanic and Caucasian women. TNBC has a lower 5-year survival rate compared to other subtypes of breast cancer and no targeted therapeutics. In order to identify novel targets for TNBC, replicate kinome-wide RNAi screens were performed with HCC1806, a basal-like TNBC cell line, using a 4-day cell viability assay. Among the RNAi hits, we identified the COASY gene, encoding Coenzyme A synthase (CoAsy), as an under-studied kinase. Thus, we sought to confirm this RNAi hit and evaluate CoAsy for its potential as a novel druggable target for TNBC. CoAsy is a bifunctional enzyme that carries out the last two steps in the coenzyme A (CoA) biosynthetic pathway, including the phosphorylation of dephospho-CoA to generate CoA. Our hypothesis is that TNBC cells require a higher level of CoA synthase activity for cell proliferation compared to normal cells and thus inhibiting CoA synthase represents a novel therapeutic strategy for TNBC. Using four different individual RNAi targeting COASY, we used transient RNAi transfection of a panel of breast cancer cell lines and a non-transformed breast cell line to determine the effect of CoAsy knock down on cell viability and proliferation. Knockdown of CoAsy protein by RNAi was demonstrated by Western blot. Transient COASY RNAi transfection inhibited the cell viability/proliferation assay for several TNBC cell lines, but not for a normal breast cell line. Thus, these data suggest that knockdown of CoAsy may preferentially inhibit cell proliferation of breast cancer cell lines. In addition, Western blot was performed to determine and compare the expression of CoAsy in a panel of breast cancer cell lines and nontransformed cell lines. Ongoing studies are investigating the dependence of cell line viability and proliferation on the expression level of CoAsy by creating stable inducible shRNA cell lines. Citation Format: Hamzah Kharabsheh, Xiyou Zhou, John Scott. Evaluating an under-studied kinase as a potential druggable target for breast cancer [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr A65.