Carbenoxolone inhibits DNA synthesis and collagen gene expression in rat hepatic stellate cells in culture

Background/Aims: This study using primary-cultured rat hepatic stellate cells (HSCs) was aimed to reveal the effect of carbenoxolone and the other gap-junction blockers on the proliferation and activation of HSCs. Methods: HSC morphology was microscopically evaluated. DNA synthesis was determined by [H-3]thymidine incorporation. Expression of HSC activation markers and cell cycle-related proteins was evaluated by Western blot. Collagen alpha1(I) mRNA expression was evaluated by quantitative reverse transcription polymerase chain reaction. Results: Carbenoxolone triggered the morphological change of activated HSCs without inducing apoptosis. Culture-induced DNA synthesis was suppressed to 22.6 and 8.51%, respectively, by 40 and 80 muM carbenoxolone. The other gap-junction blockers failed to affect the morphology and the DNA synthesis of activated HSCs. Carbenoxolone decreased the expression of cyclins D1/2 and cyclin-dependent kinases 4/6. Platelet-derived growth factor (PDGF)-BB-elicited DNA synthesis was reduced to 45.6 and 3.27%, respectively, by 40 and 80 muM carbenoxolone. Phosphorylation of c-Raf, MEK and mitogen-activated protein kinase, but not PDGF receptor beta, under PDGF-BB stimulation was attenuated by carbenoxolone. Collagen alpha1(I) mRNA expression was significantly reduced. In addition, carbenoxolone suppressed the activation process of quiescent HSCs. Conclusions: Carbenoxolone reduced the DNA synthesis and the expression of collagen alpha1(I) mRNA in activated HSCs independently of its pharmacological action as gap-junction blocker. (C) 2003 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.