Proliferation inhibition and apoptosis induction of Astragalus polysaccharides in human breast cancer MCF-7 cells

Abstract

Objective To explore the in vitro anti-breast cancer activity of a traditional Chinese medicine,Astragalus polysaccharides (APS),in MCF-7 cells.Methods The MCF-7 cells were divided into three groups:treated with different concentrations of APS (2.5,5,10 and 20 mg/L) (APS group),with 10 μmol/L cisplastin (positive control group),with equivalent volume of media (blank control group).After 48 h,methylthiazolyl tetrazolium (MTT)test was used to evaluate the proliferation inhibition and then the IC50 was calculated; acridine orange (AO)-ethidium bromide (EB) fluorescence staining was used to evaluate the induced apoptosis of MCF-7 cells; flow cytometry was used to analyze the apoptosis and cell cycle.Results After 48 h treatment,different concentrations of APS (2.5,5,10 and 20 mg/L) were shown to inhibit the proliferation of MCF-7 cells in a dose-dependent manner (r=0.985,P＜0.05),with the rates of inhibition being (4.14±2.96)％,(7.14±2.10)％,(20.13±2.33)％ and (64.66±5.15)％,respectively.These inhibition rates were significantly higher than that in blank control group (0％),but lower than that in positive control group (90.31±4.92)％.The IC50 of APS at 48 h was 16.83 mg/L.Along with higher concentrations of APS,the MCF-7 cells showed more apoptosis as reflected by an increase in brown-stained cells and typical morphology of apoptosis such as karyopyknosis.The rates of apoptosis by APS were (2.37±0.98)％,(6.76±1.31)％,(11.65±1.46)％,(20.75±2.68)％,respectively,according different levels(2.5,5,10 and 20 mg/L).These rates were higher than that in blank control group (1.14± 1.25)％,but lower than that in positive control group (35.09±2.88) ％ (all P＜0.05).Compared with blank control group,APS induced apoptosis of MCF-7 cells in a dose-dependent manner (r=0.991,P＜0.05).The rates of apoptosis increased with higher doses of APS,but were all lower than that in the positive control group.The proportion of S-phase cells increased with higher concentration of APS,but was nevertheless lower than those in blank and positive control groups (all P＜0.05),whereas the proportion of G0-G1 phase cells decreased with higher concentration of APS,but was higher than those in blank and positive control groups (all P＜0.05).Conclusion APS is effective in inhibiting proliferation and inducing apoptosis of human breast cancer MCF-7 cells by arresting the cells at S phase. Key words: Astragalan; Breast neoplasms; Cell proliferation; Apoptosis