Inhibition of proliferation, invasion and adhesion of liver cancer cells by 5-azacytidine and butyrate

Background. The prognosis for liver cancer is poor with current chemotherapeutic agents, for the most part, ineffective. We have recently shown that 5-azacytidine (5-azaC) and butyrate stimulate apoptosis in two human liver cancer cell lines (HepG2 and Hep3B). The purpose of our present study was to determine the effects of these agents on proliferation, invasion and adhesion of liver cancer cells, and to assess potential cellular mechanisms for these effects. Materials and Methods. HepG2 and Hep3B cells were treated with either 5-azaC (8 μM), sodium butyrate (35 mM), 5-azaC + butyrate or vehicle (control); proliferation, cellular invasion and adherence were determined. Western blots were performed to assess expression levels of p21(waf1), p27(kip1) and p53. Results. Treatment with 5-azaC alone inhibited invasion of Hep3B cells whereas butyrate alone inhibited invasion of HepG2 cells; the combination of 5-azaC + butyrate completely suppressed the invasion of both cell lines. Moreover, cellular adhesion and proliferation were inhibited in both cell lines by combination treatment. Levels of the Cdk inhibitor p21(waf1) were increased in HepG2 cells after 5-azaC and in both cell lines after butyrate treatment; levels of p27(kip1) were increased in both cell lines after either 5-azaC or butyrate treatment. Conclusions. Our results demonstrate that the combination of 5-azaC and butyrate effectively blocks proliferation, invasion and cellular adhesion of both HepG2 and Hep3B cells. Increases in the expression of the cell cycle inhibitory proteins, p21(waf1) and p27(kip1) suggest that these effects may be mediated through the induction of these inhibitory proteins. Agents such as 5-azaC and butyrate that target the cell cycle pathway may prove clinically useful in the adjuvant treatment of liver cancers.