Studies Of Synergistic Anti-tumor Effect And Mechanisms Of Combination Of β-aescin And 5-fluorouracil

Aim: To study the synergistic anti-tumor effect of the combination ofβ-aescin and 5-fluorouracil, and to study the mechanisms of the effect of synergy.Method: The inhibitory effects ofβ-aescin or 5-fluorouracil(5-FU) used alone on A549,H1299,SMMC-7721and Bel-7402 cells were assessed by MTT assay. To study the effect of the combination ofβ-aescin and 5-FU, two groups of combination with the ratio of concentration is 4:1and 2:1were employed to detected the inhibitory effect on the proliferation of cells. The method of isoboles-interaction index was applied to assessed the potential synergy,additivity or antagonism. To study the synergistic anti-tumor effect of combination further, the tumor models were set up by transplanting H22 or S180 in KM mice. The inhibitory rate of tumor growth was calculated. The indices of thymus and spleen were employed to assess the amendment of toxicity caused by 5-FU. The morphological change of S180 and H22 tumor cells implanted in mice was surveyed by HE dye. To discuss the mechanism of the synergy, the human hepatocellular carcinoma SMMC-7721 cells were selected to study. Cell cycle was analyzed by flow cytometry(FCM); AnnexinV-FITC Apoptosis Detection Kit was used to detect apoptosis of SMMC-7721cells. The activities of caspase-3,8 and 9 were detected by caspase-3,8,9 Colorimetric Assay Kits. Western blot was employed to detect the expression of Bcl-2.Results: The results of MTT assays showed thatβ-aescin,5-FU and their mixture could inhibit cell proliferation after 48h exposure. The analysis of isoboles-interaction index was illustrated that the combination ofβ-aescin and 5-FU inhibit cell proliferation synergistic in cell and prescription schedule manners. The results of tumor model transplanted by H22 or S180 showed that the combination could inhibit the growth of tumor in vivo. The combination could increase the thymus and spleen indices down-regulated by 5-FU and cause the morphology of tumor cells changed into necrosis. The results of FCM revealed that the combination could cause the cell cycle of SMMC-7721 accumulated in G0/G1phase significantly compared with cells treated withβ-aescin or 5-FU alone. Apoptosis was induced synergistically by combination ofβ-aescin and 5-FU compared with the drug used alone. The activities of caspase-3,8,9 were boosted significantly by combination and the expression of Bcl-2 was down-regulated markedly compared with cells treated withβ-aescin or 5-FU alone.Conclusion: The results of the present of study showed that combination ofβ-aescin and 5-FU has synergistic anti-tumor effect. The most likely mechanisms of action of synergy are the arrest of cell cycle and the induction of apoptosis, with the latter involving the activation of capase-dependent mitochondrial and death receptor pathways and the inhibition of Bcl-2 expression.