PDK4 acts via hippo signaling to inhibit ferroptosis and reduce gemcitabine sensitivity in pancreatic cancer.

Ferroptosis has been implicated in cancer chemo-resistance. The role of pyruvate dehydrogenase kinase 4 (PDK4) in gemcitabine-induced ferroptosis in Pancreatic Adenocarcinoma (PAAD) was investigated. Immunohistochemistry and RNA sequencing were used to assess PDK4 expression in gemcitabine-resistant PAAD tissues and to correlate expression with clinico-pathological features. The pancreatic cancer cell-line, ASPC1, was stably transfected to up- and downregulate PDK4 expression and proliferation (CCK-8 assay), colony formation, migration (Transwell assay), apoptosis and reactive oxygen species (flow cytometry) measured. Mitochondrial morphology was examined by electron microscopy. Expression of genes was quantified by reverse transcription-polymerase chain reaction and western blotting. Gemcitabine-resistant PAAD cells and patient tumor samples had increased PDK4 expression. PDK4 knockdown reduced ASPC cell proliferation, invasion and migration, induced morphological changes to mitochondria and increased apoptosis. Expression of glutathione peroxidase 4 and acyl-CoA synthetase long-chain family 4 and Hippo signaling proteins, TAZ and YAP, were also altered. PDK4 influenced ferroptosis in pancreatic cancer cells via an effect on Hippo signaling with implications for gemcitabine resistance.