Effect of Na(+)/K(+)-ATPase alpha1 siRNA and ouabain upon cell cycle in human hepatoma HepG2 cell and its mechanism

To investigate the in vitro anti-cancer effects of ouabain combined Na(+)/K(+)-ATPase alpha1 siRNA upon HepG2 cells and its molecular mechanism. The Na(+)/K(+)-ATPase alpha1 subunit expressions of human hepatoma tissue, normal liver tissue and human hepatoma cell lines (HepG2, SMC7721 and Bel7402) were determined. The cells received different treatments (0.03 micromol/L siRNA, 0.1 micromol/L ouabain and combination). The proliferation of HepG2 was observed by CCK-8 assay. The activity of Na(+)/K(+)-ATPase was measured. The HepG2 cell cycle distribution was detected by flow cytometry. The mRNA and protein levels of Na(+)/K(+)-ATPase alpha1 subunit, MAPK1, Cyclin A, CDK2, PCNA and P21WAF1 were detected by quantitative RT-PCR and Western blot. The gray value Na(+)/K(+)-ATPase alpha1 subunit in hepatoma tissue was 174.74 +/- 16.77 and 65.31 +/- 7.88 respectively in normal liver tissue. The Na(+)/K(+)-ATPase alpha1 subunit expression of hepatoma tissue was significantly higher than normal liver tissue(P < 0.05).Th