Thiol antioxidant and thiol-reducing agents attenuate 15-deoxy-Δ ^12,14-prostaglandin J₂-induced heme oxygenase-1 expression

Heme oxygenase-1 (HO-1) is induced as a beneficial and adaptive response in cells and tissues exposed to oxidative stress. Herein we examined how various eicosanoids affect the induction of HO-1, and the possible mechanism underlying 15-deoxy-Δ^12,14- prostaglandin J₂ (15d-PGJ₂)-induced HO-1 expression. PGH₂, PGD₂ and its metabolites of the PGJ₂ series, and PGA₁ markedly induced the protein expression of HO-1. Arachidonic acid (AA), docosahexaenoic acid (DHA), PGE₂, PGF_2α, and thromboxane B ₂ (TXB₂) were shown to have no effect on the induction of HO-1. 15d-PGJ₂ was the most potent activator achieving significance at 5 μM. Although 15d-PGJ₂ significantly activated the MAPKs of JNK and ERK, the activation of JNK and ERK did not contribute to the induction of HO-1 as determined using transfection of dominant-negative plasmids and MAPKs inhibitors. Additional experiment indicated that 15d-PGJ₂ induced HO-1 expression through peroxisome proliferator-activated receptor (PPAR)-independent pathway. 15d-PGJ₂ significantly decreased the intracellular level of reduced glutathione; and the thiol antioxidant, N-acetyl-L-cysteine (NAC), and the thiol-reducing agent, dithiothreitol (DTT), inhibited the induction of HO-1 by 15d-PGJ₂. Finally, NAC and DTT exhibited significant inhibition of HO-1 mRNA and HO-1 promoter reporter activity induced by 15d-PGJ₂. These results suggest that thiol antioxidant and reducing agents attenuate the expression of HO-1 induced by 15d-PGJ₂, and that the cellular thiol-disulfide redox status may be linked to HO-1 activation.