Effects of Inducible Nitric Oxide Synthase Derived Nitric Oxide on Apoptosis of HL60 Cells Co-cultured with RAW264. 7 Macrophages

Objective 　To study effects of inducible nitric oxide synthase (iNOS)-derived nitric oxide (NO) on apoptosis of HL60 cells co2cultured with RAW 264. 7 macrophages. Methods 　Upon stimulation with lipopolysaccharide (LPS) and interferon-γ( IFN-γ), inducible nitric oxide synthase gene was expressed in RAW 264. 7 macrophages, which caused the consequent generation of nitric oxide. Effects of nitric oxide on HL60 cells viability, expression of bcl-2 and bax protein, activity of Caspase-3 and cell apoptosis were evaluated with MTT assay, Western blot analysis, fluorescence analysis, flow cytomet ry (FCM), transmission elect ron microscopy ( TEM) and DNA agarose gelelect rophoresis. Results 　The results showed that iNOS-derived nitric oxide caused oxidative damage of HL60 cells co-cultured with RAW 264. 7 macrophages, and decreased cell viability, and evidently reduced expression of bcl-2 and increased expression of bax, and induced activity of caspase-3 and DNA f ragmentation. Conclusion 　The result s suggested important effect of iNOS-derived nitric oxide on apoptosis of cells in RAW 264. 7 macrophages.