Experimental Study Of Extracellular-regulated Kinase Signaling Pathway On The Proliferation Of Rat Hepatic Stellate Cells Stimulated By Acetaldehyde

Background and aim Hepatic stellate cells (HSC) have been considered as the unequivocal source of extracellular matrix in liver fibrosis. In recent years, how the signal transduction in HSC regulate has been still remained in radical debate. More researchers are paying close attentions to extracellular-regulated kinase(ERK) signaling pathway, as a converge or common signal pathway, among others, which regulate the HSC proliferation and differentiation. It has been confirmed that the activation of HSC triggered by direct action of acetaldehyde, as a key factor, resulting in extracelluar matrix oversecretion contributes to alcoholic hepatic fibrosis in researches. Our previous research has known ERK signaling pathway play an important role in proliferation of HSC stimulated by acetaldehyde, however, the molecular mechanism which ERK regulates HSC proliferation has not been well known. To understand the molecular mechanism which ERK regulates HSC proliferation, we sought to investigate the effect of PD98059 on p-ERK, cell proliferation, cell cycle and cyclins in rat hepatic stellate cells stimulated by acetaldehyde, so that the theoretical and experimental data can be offered for clinical therapy of liver fibrosis. Materials and Methods Rat hepatic stellate cells was cultured in vitro. HSC, pre-disposed in different dose PD98059(20,50,100μmol/L), then stimulated by acetaldehyde, were collected for detection of the level of the p-ERK, the changes of the proliferation, the expression of proliferating cell nuclear antigen(PCNA) and CyclinD1mRNA, the changes of cell cycle, by means of western blot, MTT, immunohistochemistry stain, flow cytometry, RT-PCR, respectively.Main Results(1) The cells proliferation, p-ERK level, PCNA and CyclinD1 mRNA expression were enhanced apparently after HSC were stimulated by acetaldehyde. G0/G1 to S phase transition was also accelerated in HSC stimulatedby acetaldehyde. The difference has statistical significant between experimental group and control group(P<0.05). (2) The PD98059 with the concentration of 20, 50μmol/L and 100μmol/L could significantly inhibit p-ERK level in HSC stimulated by acetaldehyde(P<0.05). The inhibition of PD98059 with the concentration of 20μmol/L on the HSC proliferation, PCNA and CyclinD1mRNA expression were not significant (P>0.05). The PD98059 with the concentration of 50μmol/L and 100μmol/L could significantly inhibit cell proliferation, PCNA and CyclinD1mRNA expression, and also inhibit G0/G1 to S phase transition of the HSC stimulated by acetaldehyde(P<0.05).Main Conclusions(1)ERK could be activated significantly after HSC were stimulated by acetaldehyde. (2) HSC proliferation stimulated by acetaldehyde is related to ERK signal transduction pathway.(3) The expression of PCNA and cyclinD1mRNA was increased ,and G0/G1 to S phase transition was also accelerated in HSC stimulated by acetaldehyde.(4) The ERK signal transduction pathway regulates the proliferation andcell cycle of rat hepatic stellate cells stimulated by acetaldehyde, which might be partly related to its regulative effect on the cell cycle, expression of PCNA and CyclinD1 mRNA.