Nitroprusside stimulates mitochondrial aconitase gene expression through the cyclic adenosine 3',5'-monosphosphate signal transduction pathway in human prostate carcinoma cells.
BACKGROUND
Mitochondrial aconitase (mACON), an iron-requiring enzyme, is a major target of nitric oxide (NO) in cells, which causes the oxidant-mediated disruption of the [4Fe-4S] prosthetic group of the enzyme. In this study, the effect of NO on mACON enzymatic activity and gene expression were investigated.


METHODS
Three NO generators, sodium nitroprusside (SNP), S-nitoso-N-acetylpenicillamine (SNAP), and 3-morpholinosydnonimine (SIN) were used to determine the regulation of mACON enzymatic activity by NO. The effect of SNP on mACON, which modulates citrate secretion and cellular bioenergetics in PC-3 cells, was investigated by determining the effect of SNP on mACON gene expression using Western blot and transient gene expression assays.


RESULTS
SNP upregulated mACON enzymatic activity and gene expression in PC-3 cells. However, treating cells with other NO generators, SNAP and SIN, resulted in decreased mACON enzymatic activity. The addition of ascorbic acid to the SNP treatment resulted in a decrease in mACON enzymatic activity and gene expression. Our results showed that both SNP and dibutyryl-cAMP increased the mACON promoter activity 2-fold while the effect was blocked by adding H-89. Mutation of the cAMP response element (CRE) to the AGAGCT abolished the activating effects of SNP and dibutyryl-cAMP on mACON promoter activity.


CONCLUSIONS
These results establish the function of nitroprusside as a signaling molecule for mACON gene expression through the cAMP signal transduction pathway in human prostatic carcinoma cells.
Department of Anatomy, Chang Gung University, 259 Wen-Hua 1st road, Kwei-Shan, Tao-Yuan 333, Taiwan, ROC. hhj143@mail.cgu.edu.tw
Horng-Heng
HH
Juang
D000154:Aconitate Hydratase / Q000096:biosynthesis* / Q000235:genetics; D001205:Ascorbic Acid / Q000494:pharmacology; D015153:Blotting, Western; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000378:metabolism / Q000502:physiology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008297:Male; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000235:genetics; D012334:RNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D016166:Free Radical Scavengers; D020030:Nitric Oxide Donors; D012334:RNA, Neoplasm; D009599:Nitroprusside; C002385:linsidomine; D026423:S-Nitroso-N-Acetylpenicillamine; D008981:Molsidomine; D000242:Cyclic AMP; C476079:ACO2 protein, human; D000154:Aconitate Hydratase; D001205:Ascorbic Acid