In vitro c-met inhibition by antisense RNA and plasmid-based RNAi down-modulates migration and invasion of hepatocellular carcinoma cells.

The receptor tyrosine kinase c-met is over-expressed in several types of human tumours. In hepatocellular carcinoma (HCC), its expression is inversely correlated to patient survival. To determine the role of c-met in the malignant properties of HCC cells, we tested the effectiveness of two ablative strategies to down-modulate c-met expression in SKHep1C3, an HCC-derived cell line, i.e. stable expression of antisense RNA c-met and RNA interference. A plasmid coding a 965-nt fragment complementary to 5' portion of c-met mRNA was constructed for the antisense strategy. RNA interference methodology was applied for transient silencing, achieved by small interfering RNAs, and for stable silencing using an RNA polymerase III promoter carrying plasmid coding small hairpin RNAs (shRNAs) that targeted c-met. The transfected cells showed consistently lower levels of c-met mRNA and protein. The results showed that the antisense and RNAi sequences chosen to target c-met mRNA reduced c-met expression efficiently and inhibited malignant properties of SKHep1C3 cells. These data indicate that c-met is an essential factor in the processes of migration and invasion of hepatocarcinoma cells; and c-met down-regulation may be included in a therapeutic strategy for HCC in experimental animal models.