Downregulation of thioredoxin-1-dependent CD95 S-nitrosation by Sorafenib reduces liver cancer

Hepatocellular carcinoma (HCC) represents 80% of the primary hepatic neoplasms. It is the sixth most frequent neoplasm, the fourth cause of cancer-related death, and 7% of registered malignancies. Sorafenib is the first line molecular targeted therapy for patients in advanced stage of HCC. The present study shows that Sorafenib exerts free radical scavenging properties associated with the downregulation of nuclear factor E2-related factor 2 (Nrf2)-regulated thioredoxin 1 (Trx1) expression in liver cancer cells. The experimental downregulation and/or overexpression strategies showed that Trx1 induced activation of nitric oxide synthase (NOS) type 3 (NOS3) and S-nitrosation (SNO) of CD95 receptor leading to an increase of caspase-8 activity and cell proliferation, as well as reduction of caspase-3 activity in liver cancer cells. In addition, Sorafenib transiently increased mRNA expression and activity of S-nitrosoglutathione reductase (GSNOR) in HepG2 cells. Different experimental models of hepatocarcinogenesis based on the subcutaneous implantation of HepG2 cells in nude mice, as well as the induction of HCC by diethylnitrosamine (DEN) confirmed the relevance of Trx1 downregulation during the proapoptotic and antiproliferative properties induced by Sorafenib. In conclusion, the induction of apoptosis and antiproliferative properties by Sorafenib were related to Trx1 downregulation that appeared to play a relevant role on SNO of NOS3 and CD95 in HepG2 cells. The transient increase of GSNOR might also participate in the deactivation of CD95-dependent proliferative signaling in liver cancer cells.
Graphical abstract Graphical Abstract. Sorafenib reduced ROS/RNS cytoplasmic concentrations which were associated with decreased Nrf2 nuclear translocation, Trx1 expression/activity, and SNO–NOS3 expression and NO intracellular generation in HepG2. The reduction of SNO–NOS3 expression and NO generation might also be influenced by the induction of transient GSNOR expression/activity and reduced NOS3 expression by Sorafenib. The diminution of SNO-CD95 expression by Sorafenib involved reduction of caspase-8 activity and cell proliferation, and increased downstream caspase-3 activity in liver cancer cells.Image 1
Highlights • Sorafenib induces mitochondrial ROS generation, but also acts as nucleophilic scavenger. • Sorafenib reduces Nrf2-depenent Trx1 expression, and SNO–NOS3 and SNO-CD95 ratios. • Sorafenib-related antitumoral in vivo activity involves diminution of Trx1 and SNO-CD95.