Mitochondrial apoptosis pathway contributes to polysaccharide of astragalus-induced apoptosis of EC9706 cells and enhances their sensitivty to cisplatin

Abstract

Objective To investigate the antiproliferative,cytotoxic,apoptogenic activities of polysaccharide of astragalus (APS) and its synergistic effects with cisplatin in inducing apoptosis of esophageal carcinoma cells.Methods Methyl thiazol tetrazolium (MTT) assay was used to detect the antiproliferative effect of APS and cisplatin on EC9706 cells,Annexin V-lluoresceine isothiocyanate (FITC)/propidium iodide (PI) stained fluorescence-activated cell sorter (FACS) was used to detect the apoptosis rate,and immunocytochemistry was used to examine cdlular localisation and B lymphocytes/leukemia-2 (bcl-2),bcl-2 associated X protein (bax),nuclear factor-κB (NF-κB) protein levels.Results APS and cisplatin produced dose-dependent inhibition of EC9706 cell growth.The apoptosis rate in APS ± cisplatin group (41.3％) was higher than in APS group (18.7％) or cisplatin group (27.6％).APS could up-regulate the grey values of Bax protein (185.54 ± 11.27),and down-reguate those of bcl-2 (179.22 ± 12.47) and NF-κB (131.66 ± 18.83) proteins.The grey values bcl-2,NF-κB and Bax in control group were 142.11 ±13.35,140.21 ± 14.75 and 199.67 ± 15.43,respectiely.Conclusion Mitochondrial apoptosis pathway contributes to APS-induced apoptosis.APS enhanced the sensitivity of EC9706 cells to cisplatin by down-regulating the expression of NF-κB protein. Key words: Esophageal carcinoma; Polysaccharide of astragalus; Cisplatin; Apoptosis; Drug-resistance