Targeting de novo lipogenesis improves gemcitabine efficacy in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive disease with few treatment options and poor survivability. In this work we sought to characterise metabolic adaptations to gemcitabine (GEMC)-based chemotherapy exposure to discover new therapeutic targets for improving treatment efficacy. We show that GEMC resistance (GEMR) upregulates de novo lipogenesis in Panc1 and MiaPaCa2 cells through increased activity and expression of acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS) and stearoyl-CoA desaturase 1 (SCD1). We also discovered alternate fatty acid desaturase 2 (FADS2) activity in Panc1 cells, which led to the production of sapienic acid (FA 16:1n-10, cis) from palmitic acid (FA 16:0). Knockdown of key lipid synthesis enzymes sensitised cells to GEMC treatment, with FAS (both cell lines), SCD1 (MiaPaCa2 only) and SCD1+FADS2 (Panc1) knockdown showing the greatest reduction in cell growth when combined with GEMC treatment. In Panc1 cells, both desaturases upregulated their activity when the alternate was knocked down, necessitating the need for dual desaturase knockdown in this cell line. PDAC cells attenuated to grow in combination GEMC/paclitaxel (CombAT) also displayed enhanced de novo lipogenesis; however, combination chemotherapy significantly downregulated FADS2 expression and activity in Panc1 CombAT cells rendering them more sensitive to SCD1 knockdown. We conclude that co-targeting lipid synthesis in PDAC could be a viable strategy for improving the efficacy of both GEMC monotherapy and combination GEMC/PTX therapy.