Abstract 1783: Understanding lipogenesis in bladder cancer

Abstract Cancer cells are known to have different metabolic needs for growth and survival and by understanding these demands of individual cancers, targeted novel therapies may be developed. Lipogenesis and ß-oxidation serve to balance lipid levels in the cell. Lipogenesis is rate limited by a series of reactions that include enzymes fatty acid synthase (FASN) and acetyl-CoA carboxylase (ACC1) that facilitate lipid formation; whereas ß-oxidation is rate limited by the transporter carnitine palmitoyltransferase 1 (CPT1) and the enzyme thiolase that catalyzes the final step of the ß-oxidation cycle. Many cancers are dependent on lipogenesis, but the role of these factors in BCa is poorly defined. The Cancer Genome Atlas was used to assess levels of relevant metabolic proteins in normal and cancerous BCa tissue, and showed FASN levels were elevated in BCa tissue and were associated with worse survival. The purpose of this project is to better understand the metabolic demands of bladder cancer (BCa) cell lines, and we hypothesized lipogenesis is a major metabolic pathway for BCa cell growth. T24, HTB-5, and HTB-9 BCa cell lines were used to evaluate the role of metabolism. CPT1 was inhibited with etomoxir, thiolase with trimetazidine, FASN with cerulenin, and ACC1 with 5- (Tetradecyloxy) -2-furoic acid (TOFA). Cell viability was assessed at 48 and 72 hours with an enzymatic activity assay measuring ß-hexosaminidase activity as a surrogate for cell proliferation. The IC50 (concentration of a drug to reduce cell proliferation by 50%) was calculated from this data. At 48 hours, cerulenin-treated cells had an IC50 of 11. 80 µM, 13. 28 µM, 18. 31 µM for HTB-9, T24, and HTB-5 respectively. At 48 hours, TOFA-treated cells had an IC50 of 64. 25 µM, 59. 29 µM, 32. 03 µM for HTB-9, T24, and HTB-5 respectively. Cellular proliferation was not inhibited by CPT1 or trimetazidine at enzymatic IC50 concentrations consistent with their known levels of efficacy. When adding the lipid palmitate (20µM) to TOFA-treated cells, it appeared to mediate a rescue of cell proliferation almost to control, although statistical significance was not achieved. Crystal violet assays were performed to assess long-term cell viability. There was visible reduction in colony formation in a dose-dependent manner at 5 µM and 10 µM cerulenin in T24 cells at 14 days of culture, and there were similar results in HTB-9 cells treated with 20 µM and 40 µM TOFA at 17 days. In both cerulenin and TOFA-treated cells, there was elevated cleaved caspase-3 protein expression, indicating initiation of apoptosis. In conclusion, inhibition of lipogenesis in BCa cell lines reduces cell viability by reducing proliferation and inducing apoptosis whereas inhibitors of ß-oxidation did not produce the same effect at relevant concentrations. These data indicate lipogenesis is a key metabolic pathway for BCa cell growth. Citation Format: Juliann Leak, David Matye, Erika Abbott, Benjamin Woolbright, John A. Taylor. Understanding lipogenesis in bladder cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 1783.