Pepstatin A attenuates the inhibitory effect of N-acetyl-L-cysteine on proliferation of hepatic myofibroblasts (stellate cells).
The pharmacological interaction between pepstatin A, a specific inhibitor of cathepsin D, and N-acetyl-L-cysteine was analyzed using hepatic stellate cells in primary culture. Isolated rat stellate cells were cultured on plastic dishes in Dulbecco's modified Eagle's medium (DMEM). Proteins and phospho-proteins were detected by Western blot. DNA synthesis was determined by [3H]thymidine uptake. Pepstatin A restored DNA synthesis of stellate cells stimulated by either platelet-derived growth factor-BB (PDGF-BB) or insulin-like growth factor-I (IGF-I), an effect that was attenuated by N-acetyl-L-cysteine. This agent induced the recovery of both the expression of PDGF receptor beta and IGF-I receptor beta and the phosphorylation of p42/44 mitogen-activated protein kinase (MAPK) and Akt under stimulation with either PDGF-BB or IGF-I, which were downregulated by N-acetyl-L-cysteine. Expression of cathepsin D was induced in activated stellate cells. These results indicate that pepstatin A hampers the inhibitory effect of N-acetyl-L-cysteine on stellate cell growth by ameliorating growth factor receptor downregulation.
Takashima
Tokuko
T
Department of Hepatology, Graduate School of Medicine, Osaka City University, 1-4-3 Asahimachi, Abeno 545-8585 Osaka, Japan.
Kawada
Norifumi
N
Maeda
Naoto
N
Okuyama
Hiroaki
H
Uyama
Naoki
N
Seki
Shuichi
S
Arakawa
Tetsuo
T
D000111:Acetylcysteine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D000818:Animals; D002402:Cathepsin D / Q000037:antagonists & inhibitors*; D002478:Cells, Cultured; D015536:Down-Regulation; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D010436:Pepstatins / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D013936:Thymidine / Q000378:metabolism
D010436:Pepstatins; D002402:Cathepsin D; C031375:pepstatin; D013936:Thymidine; D000111:Acetylcysteine