PEROXYNITRITE IS INVOLVED IN THE MITOCHONDRIAL DYSFUNCTION INDUCED BY SORAFENIB IN LIVER CANCER CELLS

Background: Sorafenib is a tyrosine kinase inhibitor (TKI) that belongs to the landscape of treatments for advanced stages of hepatocellular carcinoma (HCC). The induction of cell death and cell cycle arrest by Sorafenib has been associated with mitochondrial dysfunction in liver cancer cells. Our research aim was to decipher underlying oxidative and nitrosative stress induced by Sorafenib leading to mitochondrial dysfunction in liver cancer cells.

Methods: MnTBAP, catalase and the scavenger of peroxynitrite FeTPPs were administered to Sorafenib (0-10 μM)-treated HepG2 cells. Oxygen consumption and glycolytic flux were determined in cultured cells. Mitochondrial complex activities were measured in mitochondrial fraction and cell lysates. The protein and mRNA expression of subunits of electron transport chain (ETC) were assessed by immunoblot and RNA-seq.

Results: Sorafenib (10 μM) increased nitric oxide (NO) and superoxide anion (O₂^.-) leading to peroxynitrite generation, and drastically reduced oxygen consumption. Moreover, Sorafenib led to mitochondrial network disorganization and loss of membrane potential. The administration of FeTPPs influenced the recovery of mitochondrial network and oxygen consumption, as well as associated ATP production. Sorafenib downregulated the mRNA expression of all mitochondrial-encoded subunits of ETC and, at to a lesser extent, nuclear-encoded mitochondrial genes. The protein expression of complex I, complex III and complex IV was greatly affected by Sorafenib. Furthermore, Sorafenib diminished the activity of complex I in in-gel assays, whose expression and activity were restored by FeTPPs. However, Sorafenib did not affect the assembly of mitochondrial supercomplexes. Sorafenib altered glycolysis and reduced Krebs cycle intermediates and increased NAD/NADH ratio.

Conclusions: The induction of cell death by Sorafenib was associated with peroxynitrite generation, which impacted the expression of electron transport chain (ETC) subunits and mitochondrial functionality in liver cancer cells.