Inhibition of LPAR6 overcomes sorafenib resistance by switching glycolysis into oxidative phosphorylation in hepatocellular carcinoma

Abstract

Hepatocellular carcinoma (HCC) is one of the most threatening tumours in the world today. Pharmacological treatments for HCC mainly rely on protein kinase inhibitors, such as sorafenib and regorafenib. Even so, these approaches exhibit side effects and acquired drug resistance, which is an obstacle to HCC treatment. We have previously shown that selective lysophosphatidic acid receptor 6 (LPAR6) chemical antagonists inhibit HCC growth. Here, we investigated whether LPAR6 mediates resistance to sorafenib by affecting energy metabolism in HCC. To uncover the role of LPAR6 in drug resistance and cancer energy metabolism, we used a gain-of-function and loss-of-function approach in 2D tissue and 3D spheroids. LPAR6 was ectopically expressed in HLE cells (HLE-LPAR6) and knocked down in HepG2 (HepG2 LPAR6-shRNA). Measurements of oxygen consumption and lactate and pyruvate production were performed to assess the energy metabolism response of HCC cells to sorafenib treatment. We found that LPAR6 mediates the resistance of HCC cells to sorafenib by promoting lactic acid fermentation at the expense of oxidative phosphorylation (OXPHOS) and that the selective LPAR6 antagonist 9-xanthenyl acetate (XAA) can effectively overcome this resistance. Our study shows for the first time that an LPAR6-mediated metabolic mechanism supports sorafenib resistance in HCC and proposes a pharmacological approach to overcome it.