Inhibitory effect of Silibinin combined with 5-FU on MGC-803 gastric cancer cell proliferation and the mechanisms

Aim: To investigate the synergistic effect of Silibinin combined with 5-fluorouracil( 5-FU) on gastric cancer MGC-803 cells and the possible mechanism. Methods: MTT assay was used to determine the inhibitory effect of Silibinin on gastric cancer MGC-803 cells and hepatocyte L02 cells. Changes in cell cycle and the apoptotic cell percentage were determined by Flow Cytometry. The expression of cell cycle related proteins and apoptosis associated proteins were analyzed by Western blotting. Results: MTT method was used to determine the IC20 value and IC50 value for hepatocyte L02 cells. IC20 concentration of Silibinin combined with 5-FU at different concentrations were incubated with MGC-803 cells for 48 hours,MTT assay was used to measure the proliferation inhibition effects. After MGC-803 cells were in-cubated with Silibinin combined with 5-FU for 48 hours,the cell cycle of MGC-803 was inhibited by Silibinin at different concentrations,in a dose-dependent manner( P 0. 05),but no obvious effects were found on the proliferation of hepatocyte L02 cells. The IC20 and IC50 for Silibinin against gastric cancer MGC-803 cells after incubation for 48 hours were found to be 144. 6 and 214. 7 μmol / L,respectively. The chemo-therapeutic effects of 5-fluorouracil on MGC-803 cells were enhanced when combined with Silibinin,and the drug sensitivity was increased by about 5. 73 times. PI staining analysis showed that cell cycle was arrested in G0 / G1 phase. Annexin V-FITC / PI staining analysis also showed a dose-dependent effect on the apoptotic cells. Western blotting showed that the expression of cell cycle related protein CDK6 was decreased while that of P15 was increased. The expressions of apoptosis associated proteins, pro-Caspase-9,pro-Caspase-3,Bcl-2,Bcl-xL,were found to be decreased significantly,but expression of Bax remained unchanged. Conclusion: Silibinin has synergistic inhibitory effect with 5-fluorouracil on MGC-803 cells. Silibinin combined with 5-fluorouracil might inhibit cell cycle in G0 / G1 phase and induce cell apoptosis through the mitochondrial pathway.