Armc8 regulates the invasive ability of hepatocellular carcinoma through E-cadherin/catenin complex.

Armc8 (armadillo-repeat-containing protein 8) was proved to promote disruption of E-cadherin complex through regulating α-catenin degradation. In this study, we investigated Armc8 expression in hepatocellular carcinoma using immunohistochemistry (IHC). The positive rate of Armc8 expression in hepatocellular carcinoma was 53.9 % and higher than that in normal hepatic tissues (9.2 %) (p < 0.05). Clinicopathological analysis shows that Armc8 expression in hepatocellular carcinoma was significantly associated with larger tumor size (≥5 cm), multiple tumor numbers, higher pathological grade (media and poor), advanced TNM stages (II/III), and advanced BCLC stages (B/C). Western blot study also detected higher Armc8 expression in hepatocellular carcinoma cells including HepG2, HCC97L, and SMMC-7721 than in human hepatic cell Bel-7402. We further use specific small interfering RNAs (siRNAs) to knock down Armc8 expression in HepG2 cells and found that knockdown of Armc8 expression significantly inhibited the invasive ability of HepG2 cells. Downregulation of Armc8 expression significantly upregulated α-catenin, β-catenin, and E-cadherin expression in HepG2 cells. Immunofluorescent study shows that knockdown of Armc8 expression restored E-cadherin expression in membrane of HepG2 cells. These results indicate that Armc8 may be a potential cancer marker in hepatocellular carcinoma and may regulate cancer invasion through E-cadherin/catenin complex.