Objective: To investigate the inhibitory effects of genistein on tyrosine protein kinase (TPK)-mitogen activated protein kinase (MAPK) signal transduction pathway in hypertrophic scar fibroblasts (HSFb), in order to explore the molecular mechanism of inhibition of scar hyperplasia by genistein.
Methods: HSFbs were isolated from human hypertrophic scar tissues and cultured in vitro. The cells were treated by genistein in different concentrations (25, 50, 100 micromol/L, respectively), followed by basic fibroblast growth factor (bFGF) stimulation. The activity of TPK was assessed with [gamma-32P] ATP substrate incorporation. The phosphorylation protein expression levels of main signal molecules in TPK-Ras-MAPK pathway including c-Raf, MEKl/2, extracellular signal regulated kinase (ERK), p38MAPK, c-Jun N-terminal kinase (JNK) were determined by Western blot. HSFbs treated with dimethylsulfoxide (DMSO) were used as control group.
Results: After being treated with genistein in concentration of 25, 50, 100 micromol/L, the activity of TPK in HSFbs was depressed significantly [(7.15 +/- 0.35) x 10(5), (5.62 +/- 0.88) x 10(5), (5.62 +/-0.88) x 10(5) 10(5) pmol x min(-1) x mg(-1), respectively] when compared with that in control group [(8.92 +/- 0.28) x 10(5) pmol x min(-1) x mg(-1), P < 0.05]. Compared with those in control group,the phosphorylation protein expression levels of c-Raf, MEK1/2, ERK1/2 and p38 MAPK were lowered in different degree (P < 0.05 or P < 0.01) after genistein treatment. The phospho-JNK levels after treatment with genistein were similar to that of control group. Under the condition of pretreatment with genistein, the activities of TPK and signal pathway protein expressions in HSFb showed a downward trend after stimulation with bFGF.
Conclusion: Genistein can effect the proliferation and activation of HSFb by inhibiting the phosphorylation of receptor of TPK signal transduction pathway (TPK --> Raf --> MEK --> ERK/p38).