Hepatocyte growth factor induces colonic cancer cell invasiveness via enhanced motility and protease overproduction. Evidence for PI3 kinase and PKC involvement

Tumour progression to the metastatic phenotype is mainly dependent on tumou r cell invasiveness, Cell migration is a crucial step in this process. Here we investigate the effect of hepatocyte growth factor (HGF) on the inducti on of in vitro invasiveness of poorly aggressive Caco-2 colonic cancer epit helial cells, Invasion assays through a Matrigel barrier were performed. Pr oteases were assessed by zymography, reverse transcription-polymerase chain reaction and immunoblotting. Caco-2 cells were found to express HGF recept or but not HGF and to secrete several proteases, namely matrix metalloprote inase-1 (MMP-1), MMP-2, possibly MMP-9 and urokinase plasminogen activator (uPA), Exogenous HGF promoted invasiveness of Caco-2 cells through an artif icial basement membrane matrix and enhanced their production of proteases, In addition, analyses of media at the end of invasion assays indicated that anti-HGF antibody inhibited protease production in parallel with cell inva sion, The involvement of proteases in the HGF-induced invasion process was further investigated using either a synthetic general MMP inhibitor or neut ralizing antibodies against MMPs or uPA. All components significantly inhib ited HGF-promoted cell invasion, Moreover, specific inhibitors of PKC alpha /beta1 and PI3 kinase also decreased both HGF-promoted cell invasion and pr otease expression in invasion assay media. Thus, our findings provide evide nce that the process of HGF-activated invasiveness of Caco-2 cells involves PI3 kinase and PKC and results from close association of two events, stimu lation of cell motile activity and concomitant overproduction of proteases, which permits cell migration through a degraded extracellular matrix.