ABSTRACT
OBJECTIVE: Pancreatic stellate cells (PSC) are considered as the principal effector cells in pancreatic fibrosis. We studied the role of platelet-derived growth factor (PDGF) in the activation of PSC. METHODS: Cultured rat PSC were co-incubated with PDGF-BB (25 ng/mL) and different doses (0-40 ng/mL) of PD98059, a specific inhibitor of extracellular signal-regulated kinase (ERK). Expressions of p ERK1 protein and of collagen a1(I) mRNA were measured. RESULTS: Expression of p ERK1 protein was up-regulated by PDGF-BB, and was down-regulated in a dose-dependent manner by PD98059. Expression of collagen a1(I) mRNA also showed an increase with PDGF-BB and non-dose-dependent inhibition by PD98059. CONCLUSION: Our findings suggest that PSC activation is mediated by PDGF signal pathway, and ERK1 protein plays an important role in this activation.
Subject(s)
Animals , Calcium-Calmodulin-Dependent Protein Kinases/antagonists & inhibitors , Collagen Type I/antagonists & inhibitors , Flavonoids/pharmacology , Male , Pancreas/cytology , Platelet-Derived Growth Factor/pharmacology , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Reverse Transcriptase Polymerase Chain Reaction , eIF-2 Kinase/antagonists & inhibitorsABSTRACT
Summary: To determine the biological effects of extracelluar signal regulated kinase (ERK) specific inhibitor PD98059 on pancreatic stellate cells (PSCs) activated by platelet-derived factor-BB (PDGF-BB), cultured rat PSCs were co-incubated at 37 ℃ for 24 h with 25 ng/ml PDGF-BB and different doses of PD98059 (ranging from 5 ng/ml to 40 ng/ml). Expression of pERK1 protein was detected by Western blot and collagen α1 (Ⅰ) mRNA was tested by reverse transcription-polymerase chain reaction (RT-PCR). Our results showed that there were statistical differences in the expression of pERK1 protein in all groups. Expression of pERK1 protein was up-regulated in the group treated by PDGF-BB, and gradually down-regulated in the other groups treated by PD98059 of different doses. An excellent positive correlation was revealed between the inhibitory effect and PD98059 concentrations. It was also observed that the expression of collagen α1 (Ⅰ) mRNA had similar response to pERK1. The level of collagen α1 (Ⅰ) mRNA was the highest in the PDGF-BB group, and gradually reduced in the other groups treated by PD98059 of different doses. It is concluded that expression of pERK1 protein and collagen α1 (Ⅰ) mRNA was up-regulated in rat PSCs activated by PDGF-BB. Meanwhile, PD98059 could inhibit PSCs activation mediated by PDGF. It is suggested that ERK1 protein plays an important role on PSCs activation mediated by PDGF signal pathway.