siRNA-Mediated β-Catenin Knockdown in Human Hepatoma Cells Results in Decreased Growth and Survival

beta-Catenin, the chief oncogenic component of the canonical Wnt pathway, is known to be involved in a variety of cancers, including hepatocellular carcinoma (HCC). Although the mechanism of beta-catenin activation in HCC is multifactorial, it is indisputably implicated at various stages of hepatocarcinogenesis, making it an attractive therapeutic target. Here we investigate the effect of small interfering RNA-mediated beta-catenin knockdown on the growth and survival of human hepatoma cell lines with (HepG2) and without (Hep3B) beta-catenin mutations. Transfection of HepG2 and Hep3B cells with human beta-catenin (CTNNB1) small interfering RNA resulted in a significant beta-catenin decrease, as confirmed by Western blot analyses and immunofluorescence, also leading to decreased expression of known target genes such as cyclin D1 and glutamine synthetase. The decrease in beta-catenin activity was confirmed by TOPflash reporter luciferase assay. The functional impact of diminished beta-catenin was exhibited as temporal decrease in tumor cell viability by the MTT assay. A concomitant decrease in tumor cell proliferation was also evident with (3)Hthymidine incorporation and verified with soft agar assays. Thus, beta-catenin is essential for the survival and growth of hepatoma cells independent of mutations in the beta-catenin gene and provide a proof of principle for the significance of the therapeutic inhibition of beta-catenin in HCC.