Synthetic β-nitrostyrene derivative CYT-Rx20 as inhibitor of oral cancer cell proliferation and tumor growth through glutathione suppression and reactive oxygen species induction

Background: The β-nitrostyrene family possesses anticancer properties. In this study, β-nitrostyrene derivative CYT-Rx20 (3′-hydroxy-4′-methoxy-β-methyl-β-nitrostyrene) was synthesized and investigated its anticancer activity in oral cancer. Methods: Anticancer activity of CYT-Rx20 and the underlying mechanisms were analyzed using cell viability assay, reactive oxygen species (ROS) generation assay, fluorescence-activated cell sorter analysis, annexin V staining, comet assay, glutathione (GSH)/glutathione disulfide (GSSG) ratio, immunoblotting, soft agar assay, nude mice xenograft study, and immunohistochemistry. Results: CYT-Rx20-induced cell apoptosis via ROS generation and mitochondrial membrane potential reduction, associated with release of mitochondrial cytochrome C to cytosol and activation of downstream caspases and poly ADP-ribose polymerase (PARP). Furthermore, CYT-Rx20 induced mitochondrial ROS accumulation and mitochondrial dysfunction, followed by GSH downregulation. CYT-Rx20-induced cell apoptosis, ROS generation, and DNA damage were reversed by thiol antioxidants. In nude mice, CYT-Rx20 inhibited oral tumor growth accompanied by increased expression of γH2AX, GSH reductase, and cleaved-caspase-3. Conclusion: CYT-Rx20 has the potential to be further developed into an antioral cancer drug clinically.