TY - JOUR T1 - Nitric Oxide Production by the Vacuolar-Type (H<sup>+</sup>)-ATPase Inhibitors Bafilomycin A1 and Concanamycin A and Its Possible Role in Apoptosis in RAW 264.7 Cells JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 672 LP - 681 DO - 10.1124/jpet.106.109280 VL - 319 IS - 2 AU - JangJa Hong AU - Yasuhiro Nakano AU - Aya Yokomakura AU - Kenji Ishihara AU - Soonjoo Kim AU - Young-Sook Kang AU - Kazuo Ohuchi Y1 - 2006/11/01 UR - http://jpet.aspetjournals.org/content/319/2/672.abstract N2 - In the mouse leukemic monocyte cell line RAW 264.7, the vacuolar-type (H+)-ATPase (V-ATPase) inhibitors bafilomycin A1 and concanamycin A induced nitric oxide (NO) production through the expression of inducible nitric-oxide synthase mRNA and its protein and decreased cell growth and survival as determined by 3-(4,5-dimethyl(thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Bafilomycin A1 and concanamycin A activated nuclear factor (NF)-κB and activator protein-1 and decreased the level of IκB-α and increased that of phosphorylated c-Jun N-terminal kinase (JNK). NO production induced by these V-ATPase inhibitors was suppressed by the NF-κB inhibitor Bay 11-7082 [(E)3-[(4-methylphenyl)sulfonyl])-2-propenenitrile] and the JNK inhibitor SP600125 [anthra[1,9-cd]pyrazol-6(2H)-one] in parallel with the partial alleviation of the V-ATPase inhibitor-induced decrease in MTT response. The Na+,K+-ATPase inhibitor dibucaine and the F-ATPase inhibitor oligomycin did not induce NO production at which concentrations the MTT response was decreased. The NO donor S-nitroso-N-acetyl-dl-penicillamine further lowered the V-ATPase inhibitor-induced decrease in the MTT response, and the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, sodium salt (carboxy-PTIO) alleviated it partially. Mitochondrial depolarization, an index of apoptosis, was induced by bafilomycin A1 and concanamycin A. On treatment with the nitric-oxide synthase inhibitor NG-monomethyl-l-arginine acetate, the disruption of mitochondrial membrane potential induced by bafilomycin A1 and concanamycin A was alleviated partially in parallel with the decrease in NO production. Carboxy-PTIO also alleviated it partially. Our findings suggest that the V-ATPase inhibitors bafilomycin A1 and concanamycin A similarly induce NO production and the newly produced NO participates partially in the V-ATPase inhibitor-induced apoptosis in RAW 264.7 cells. The American Society for Pharmacology and Experimental Therapeutics ER -