PP65 - Regulation of cell death receptor S-nitrosylation and apoptotic signaling by Sorafenib in hepatoblastoma cells

Abstract

Nitric oxide (NO) plays a relevant role during cell death regulation that limits the survival of tumor cells. We have recently shown that the overexpression of nitric oxide synthase type III (NOS-3) induces oxidative and nitrosative stress, p53 and cell death receptor expression and apoptosis in hepatoma cells. Sorafenib is the unique recommended molecular-targeted drug for the treatment of patients with advanced hepatocellular carcinoma. The present study was addressed to elucidate the potential role of NO during Sorafenib-induced cell death in hepatoblastoma cells. We determined the intra- and extracellular NO concentration, cell death receptor expression and their S-nitrosylation modifications, and apoptotic markers in Sorafenib-treated HepG2 cells. The effect of NO donors on above parameters has also been determined. Sorafenib induced cell death in HepG2 cells. However, low concentration of the drug (10 nM) increased the expression of cell death receptors and extrinsic apoptotic pathway (caspase-8) that both diminished at higher concentrations of the drug (10 µM). High doses of Sorafenib correlated to a rise of caspase-9 and caspase-3 activities, as well as DNA fragmentation in HepG2 cells. The shift of cell death signaling pathway was associated with a reduction of S-nitrosylation of cell death receptors in cells treated with Sorafenib. The administration of NO donors increased S-nitrosylation of cell death receptors and overall induction of cell death markers in control and Sorafenib-treated cells. In conclusion, Sorafenib induced alteration of cell death receptor S-nitrosylation status which may have a relevant repercussion on cell death shift from the extrinsic to intrinsic apoptotic signaling in hepatoblastoma cells.