Oleic acid fuels cisplatin-resistant ovarian cancer through FABP4-driven lipid uptake

BACKGROUND: Ovarian cancer (OC) depends on lipids as fuel for metastasis and growth. We previously showed that cisplatin resistant (Pt-R) OC cells uptake higher amounts of fatty acids (FAs) compared to sensitive (Pt-S) cells, a process which facilitates cancer cell survival under cisplatin-induced oxidative stress. METHODS: Isogenic pairs of Pt-S and Pt-R OC cell lines were cultured in low serum conditions supplemented with either 50 μM oleic acid (OA, unsaturated) or 50 μM palmitic acid (PA, saturated) and used for viability assays, RNA-Sequencing, and cell cycle analysis. The effects of an OA enriched diet were assessed in intraperitoneal ovarian xenografts. The FABP inhibitor BMS-309403 was used to block lipid import in vitro and in vivo. RESULTS: Pt-R cells were less viable than Pt-S cells under serum depletion and OA rescued starvation induced inhibition of cell proliferation, with more significant effects in Pt-R compared to Pt-S cells. RNA-sequencing showed that OA promoted upregulation of cell cycle-related pathways, including G2/M checkpoints, driven by the transcription factor E2F1. Supplementation with OA increased S- and G2/M phase cell populations in both Pt-S and Pt-R cells (p < 0.05) and E2F1 inhibition reduced OA-induced cell proliferation. An OA enriched diet promoted the growth and peritoneal dissemination of Pt-R ovarian xenografts. When co-cultured with adipocytes, Pt-R cells expressed higher levels of FA transporter proteins FABP4 and CD36 compared to sensitive cells and FABP4 expression was upregulated in paired metastatic and recurrent vs. primary human ovarian tumors (p < 0.05). An FABP inhibitor sensitized OC cells to cisplatin and suppressed the in vivo growth of Pt-R xenografts and patient derived xenografts. CONCLUSIONS: Pt-R OC cells harbor heightened dependence on unsaturated FAs compared to Pt-S cells and upregulate key transporters to increase FAs uptake. OA supports the proliferation of Pt-R cells in vitro and in vivo and a combination of carboplatin and FABP4 inhibitor reduces OC growth in vivo. These findings suggest that lipid composition may influence therapeutic response and raise important considerations for dietary guidance in patients with cancer.