Induction of MRP1 and gamma-glutamylcysteine synthetase gene expression byinterleukin 1 beta is mediated by nitric oxide-related signalings in humancolorectal cancer cells

Treatment of human colorectal cancer cells HT29 with interleukin 1 beta (IL -1 beta) induces expression of the multidrug resistance protein (MRP1) gene encoding the ATP-dependent glutathione S-conjugate export (GS-X) pump and the gamma-glutamyl cysteine synthetase (gamma-GCSh) gene encoding heavy (ca talytic) subunit of gamma-glutamylcysteine synthetase, the rate-limiting en zyme For the biosynthesis of glutathione (GSH). The induction can be suppre ssed by N-G-methyl-L-arginine, a specific inhibitor of nitric oxide synthas e (NOS), These results suggest that IL-1 beta-mediated MRP1 and gamma-GCSh induction involve nitric oxide (NO)-related signaling. Further supports to the involvement of NO in the induction of MRP1 and gamma-GCSh expression ar e made by the following observations. ii) Expression of MRP1 and gamma-GCSh genes were induced by treating the cells with NO donors, i.e., S-nitro-N-a cetyl-D,L-penicillamide (SNAP) and S-nitroso-L-glutathione, in a concentrat ion-dependent manner. iii) Ectopic expression of inducible NOS (iNOS) activ ity by transfecting expressible recombinant iNOS cDNA encoding functional i NOS but not the nonfunctional version resulted in elevated expression of MR P1 and gamma-GCSh. We also demonstrated that HT-29 cells treated with eithe r 1L-1 beta or SNAP induced ceramide production, and addition of C2 or C6 c eramides into cultured HT-29 cells resulted in induction of gamma-GCSh but not MRP1 expression. Collectively, our results demonstrate that induction o f MRP1 and gamma-GCSh by IL-1 beta is regulated, at least in part, by an NO -related signaling, and induction of gamma-GCSh is by NO-related ceramide s ignaling, (C) 2000 Wiley-Liss, Inc.