Compound C stimulates heme oxygenase‐1 gene expression in human endothelial cells

Compound C (6‐[4‐(2‐piperidin‐1‐yl‐ethoxy)‐phenyl]‐3‐pyridin‐4‐yl‐pyrazolo[1,5‐a]‐pyrimidine) is a cell‐permeable inhibitor of adenosine monophosphate‐activated protein kinase (AMPK) that is often used to determine the role of AMPK in endothelial cells (ECs). However, several AMPK‐independent actions of compound C have recently been discovered. In the present study, we investigated whether compound C regulates the expression of heme oxygenase‐1 (HO‐1) in cultured human umbilical vein ECs. Compound C (2–20μM) stimulated a concentration‐ and time‐dependent increase in HO‐1 mRNA and protein. The induction of HO‐1 by compound C was dependent on de novo RNA synthesis since it was blocked by the transcriptional inhibitor, actinomycin D. Furthermore, the compound C‐mediated induction of HO‐1 was associated with an increase in the production of reactive oxygen species and a decline in intracellular glutathione levels. Interestingly, administration of the glutathione donor N‐acetyl‐L‐cysteine blocked the induction of HO‐1 by compound C while the nitric oxide synthase inhibitor, methyl‐L‐arginine, and the peroxynitrite scavenger, uric acid, had no effect. In conclusion, this study demonstrates that compound C stimulates HO‐1 gene expression in human ECs via a transcriptional mechanism that is sensitive to oxidative but not nitrosative stress. Supported by NIH grants HL59976, HL74966 and HL77288.