Tyrosine phosphorylation of phospholipase Cγ in c-met/HGF receptor-stimulated hepatocytes: Comparison with HepG2 hepatocarcinoma cells

Hepatocyte growth factor (HGF) stimulates inositol 1,4,5-trisphosphate (InsP₃) formation in rat primary cultured hepatocytes, which is inhibited by the pretreatment with a tyrosine kinase inhibitor, genistein. This lnsP₃ production was coincident with tyrosine phosphorylation of phospholipase Cγ (PLCγ), detected in immunoprecipitates with anti-PLCγ, suggesting activation mechanism of PLCγ by tyrosine phosphorylation. However, in human hepatocarcinoma HepG2 cells, HGF, which suppresses cell growth, causes neither phosphorylation of PLCγ nor lnsP₃ formation. The results suggests that PLCγ in normal hepatocytes was activated by HGF through tyrosine kinase of HGF receptor.