Investigation on low doses of metformin induce hepatoma cells senescence and its underlying mechanism

Abstract

Objective To explore the effect of metformin on hepatoma cells senescence and the underlying mechanism.Methods Cell proliferation,cycle and apoptosis were examined by MTS and flow cytometry assay in response to different concentrations of metformin(0,0.01,0.1,1,10 and 50mmol/L).Senescence-associated β-galactosidase (SA-β-ga1) staining and senescence marker Dec1 protein levels were used to evaluate the effect of metformin on hepatoma cells senescence.In addition,protein expression of p-AMPK,p-ACC and AMPK was detected by Western blot analysis.Results Metformin suppressed proliferation of HepG2 cells in a dose-dependent manner.High concentrations of metformin (10 and 50mmol/L) promoted cell apoptosis,while lower doses of metformin (0.01,0.1 and 1mmol/L) led to enlarged and flatten senescent morphology and increased SA-β-ga1 positive cells.Moreover,cell cycle was blocked in G0/G1 phase and protein levels of senescent marker Dec1,p-AMPK and p-ACC were significantly enhanced,whereas AMPK protein expression was almost unchanged.Conclusion We showed here that high dose of metformin promotes HepG2 cells apoptosis,but low doses of metformin induce cellular senescence,which may be related to the activation of AMPK signaling.These data will provide vital evidence for improving the outcome of comprehensive treatment in HCC patients by driving hepatoma cells to undergo senescence. Key words: Metformin; Liver neoplasms ; Cell aging; Apoptosis