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Abstract 318: Inhibition of FASN induces apoptosis and senescence in breast cancer

Fatty Acid Synthase (FASN), the key multienzyme in de novo lipogenesis, is upregulated and activated in numerous carcinomas, including breast cancer. Fatty acids play a fundamental role in cellular structure, energy production and storage and are intermediates in the biosynthesis of hormones and other biologic molecules. Therefore, FASN is a novel therapeutic target for treatment in cancer cells that have upregulated FASN protein. BT474 breast cancer cells, which overexpress FASN, were treated with a pharmacologic FASN inhibitor and resulted in apoptosis in a dose-dependent manner. Inhibition of FASN simultaneously upregulates the pro-apoptotic BCL2 family members Bim, Puma, and Noxa; additionally, FASN inhibition alters the NDAPH/NADP+ balance and induces reactive oxygen species (ROS) production. Most significantly, FASN inhibition induces sensitization of breast cancer cells to the BH3 mimetic navitoclax, a potential opportunity to use BH3 mimetics for the treatment of breast carcinomas. These results support further preclinical and potentially clinical development of a dual FASN and Bcl-2 treatment for breast cancer tumors that express FASN. In addition to apoptosis, there is an increase in cellular senescence in breast cancer cells overexpressing FASN when treated with FASN inhibitors. The increase in ROS, a known effect of FASN inhibition, is known to induce cellular stress, resulting in both apoptosis and senescence. Increased senescence was initially observed by x-gal staining of BT474 cells treated with FASN inhibitors via microscopy and FLOW. We also observed an increased expression of several pro-senescent genes both at the protein and mRNA levels, including p16/INK4a, p14ARF/p19ARF, p15, and p21. A hallmark of age-induced cellular senescence is the shortening of telomeres. However, telomere shortening was not observed, suggesting that senescence was a result of FASN inhibition and activation of senescence-induced genes. Therefore, inhibition of FASN appears to be an ideal target for therapeutic treatment of breast cancers that overexpress FASN through both apoptosis and senescence. Citation Format: Travis Vander Steen, Ruth Lupu. Inhibition of FASN induces apoptosis and senescence in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 318.