SCD1/FADS2 fatty acid desaturases equipoise lipid metabolic activity and redox-driven ferroptosis in ascites-derived ovarian cancer cells

The omental conditioned medium (OCM) was established to imitate the omental or ascites microenvironment. Mass spectrometry, RT-qPCR, IHC, and western blot assays were applied to evaluate human fatty acid desaturases expressions and activities. Pharmaceutical inhibition and genetic ablation of SCD1/FADS2 were performed to observe the oncogenic capacities. RNA sequencing, lipid peroxidation, cellular iron, ROS, and Mito-Stress assays were applied to examine ferroptosis. OvCa patient-derived organoid and mouse model of peritoneal metastases were used to evaluate the combined effect of SCD1/FADS2 inhibitors with cisplatin.

We found that two critical fatty acid desaturases, stearoyl-CoA desaturase-1 (SCD1) and acyl-CoA 6-desaturase (FADS2), were aberrantly upregulated, accelerating lipid metabolic activities and tumor aggressiveness of ascites-derived OvCa cells. Lipidomic analysis revealed that the elevation of unsaturated fatty acids (UFAs) was positively associated with SCD1/FADS2 levels and the oncogenic capacities of OvCa cells. In contrast, pharmaceutical inhibition and genetic ablation of SCD1/FADS2 retarded tumor growth, cancer stem cell (CSC) formation and reduced platinum resistance. Inhibition of SCD1/FADS2 directly downregulated GPX4 and the GSH/GSSG ratio, causing disruption of the cellular/mitochondrial redox balance and subsequently, iron-mediated lipid peroxidation and mitochondrial dysfunction in ascites-derived OvCa cells.