Nitric Oxide Regulates Cell Sensitivity to Cisplatin-Induced Apoptosis through S-Nitrosylation and Inhibition of Bcl-2 Ubiquitination

Abstract

Cisplatin is a potent cytotoxic agent commonly used for the treatment of solid tumors. However, tumor cell-acquired resistance to cisplatin-induced apoptosis is a major limitation for efficient therapy, as frequently observed in human lung cancer. Nitric oxide (NO) is a key regulator of apoptosis, but its role in cisplatin-induced cell death and the underlying mechanism are largely unknown. Previous studies indicate increased NO synthase activity and elevated NO production in lung carcinomas, which correlate with the incidence of chemotherapeutic resistance. Here, we show that NO impairs the apoptotic function of cells and increases their resistance to cisplatin-induced cell death in human lung carcinoma H-460 cells. The NO donors sodium nitroprusside and dipropylenetriamine NONOate were able to inhibit cisplatin-induced cell death, whereas the NO inhibitors aminoguanidine and 2-(4-carboxyphenyl)-4,4,5,5-tetra-methylimidazoline-1-oxyl-3-oxide had opposite effect. Cisplatin resistance in H-460 cells is mediated by Bcl-2, and NO up-regulates its expression by preventing the degradation of Bcl-2 via ubiquitin-proteasome pathway. Cisplatin-induced generation of reactive oxygen species causes dephosphorylation and degradation of Bcl-2. In contrast, generation of NO has no effect on Bcl-2 phosphorylation but induces S-nitrosylation of the protein, which inhibits its ubiquitination and subsequent proteasomal degradation. These findings indicate a novel pathway for NO regulation of Bcl-2, which provides a key mechanism for cisplatin resistance and its potential modulation for improved cancer chemotherapy.

Nitric Oxide Boosts Chemoimmunotherapy via Inhibition of Acid Sphingomyelinase in a Mouse Model of Melanoma

“…The protocol we used was designed to expose DCs to NO selectively and only ex vivo to minimize the systemic effects of NO in vivo. These effects of NO in the case of tumors are complex, resulting from a combination of cytotoxic and cytostatic actions on tumor cells, and protumorigenic functions, including stimulation of angiogenesis and down-regulation of immune responses (13,14); in addition, systemic NO may change sensitivity to anticancer drugs in vivo (18)(19)(20)(21)(22)(23).…”

Nitric oxide induces cancer stem cell-like phenotypes in human lung cancer cells

“…Elevated NO levels have been associated with cancer cell behaviors such as anoikis resistance, increased cell motility, and chemoresistance (8,60,67). To test whether NO might affect epithelial-mesenchymal transition (EMT) properties of lung cancer cells, we first determined the appropriate noncytotoxic concentrations of NO donor used in this study.…”

“…Not only is NOS expression detectable in various cancers, but also the NO level is frequently upregulated in tumor areas (26,36). Previous studies indicated that NO could render cells resistant to death induced by various stimuli (7,8,67). NO also regulates cancer cell migration and invasion (60), and increased NOS expression and activity have been reported in metastatic lung cancer cells (57).…”

Cycloartobiloxanthone Induces Human Lung Cancer Cell Apoptosis via Mitochondria-dependent Apoptotic Pathway

“…Amplification and overexpression of BCL2 occurs in many malignancies, including small cell lung carcinoma, and impairs intrinsic apoptotic signaling (16). Moreover, the overexpression of BCL2 has been showed to inhibit cisplatininduced cell death in non-small cell lung cancer H460 cells (17). The findings of the current study indicate that, by targeting MCL1 and BCL2 proteins, cycloartobiloxanthone may have utility in the treatment of lung cancer.…”