Gene Expression Profiling Elucidates Cellular Responses to NCX4040 in Human Ovarian Tumor Cells: Implications in the Mechanisms of Action of NCX4040

SIMPLE SUMMARY: The nitric oxide donor, NCX4040, a non-steroidal anti-inflammatory-NO donor, is cytotoxic to a number of human tumors, including ovarian tumors cells. It has been shown to be safe in vivo. While the precise mechanism of action of NCX4040 is not clear at this time, NCX4040 has been reported to generate both reactive oxygen species (ROS) and reactive nitrogen species (RNS), causing significant DNA damage in tumor cells. In this study, we provide evidence that NCX4040 induces the differential induction of oxidative stress genes, inflammatory response genes (TNF, IL-1, IL-6 and COX2), DNA damage response and MAP kinase response genes in human ovarian tumor cells. Our studies strongly suggest that formation of ROS/RNS from both induction of NOX and CHAC1 which causes a significant depletion of GSH that results in oxidative stress. Furthermore, NCX4040 treatment induced TNF-dependent pathways which further increases oxidative stress in ovarian tumor cells, resulting in enhanced NCX4040-mediated cell death from apoptosis and/or ferroptosis. ABSTRACT: The nitric oxide donor, NCX4040 is a non-steroidal anti-inflammatory-NO donor and has been shown to be extremely cytotoxic to a number of human tumors, including ovarian tumors cells. We have found that NCX4040 is cytotoxic against both OVCAR-8 and its adriamycin-selected OVCAR-8 variant (NCI/ADR-RES) tumor cell lines. While the mechanism of action of NCX4040 is not entirely clear, we as well as others have shown that NCX4040 generates reactive oxygen species (ROS) and induces DNA damage in tumor cells. Recently, we have reported that NCX4040 treatment resulted in a significant depletion of cellular glutathione, and formation of both reactive oxygen and nitrogen species (ROS/RNS), resulting in oxidative stress in these tumor cells. Furthermore, our results indicated that more ROS/RNS were generated in OVCAR-8 cells than in NCI/ADR-RES cells due to increased activities of superoxide dismutase (SOD), glutathione peroxidase and transferases expressed in NCI/ADR-RES cells. Further studies suggested that NCX4040-induced cell death may be mediated by peroxynitrite formed from NCX4040 in cells. In this study we used microarray analysis following NCX4040 treatment of both OVCAR-8 and its ADR-resistant variant to identify various molecular pathways involved in NCX4040-induced cell death. Here, we report that NCX4040 treatment resulted in the differential induction of oxidative stress genes, inflammatory response genes (TNF, IL-1, IL-6 and COX2), DNA damage response and MAP kinase response genes. A mechanism of tumor cell death is proposed based on our findings where oxidative stress is induced by NCX4040 from simultaneous induction of NOX4, TNF-α and CHAC1 in tumor cell death.