Extract from Astragalus membranaceus inhibit breast cancer cells proliferation via PI3K/AKT/mTOR signaling pathway

Background: Astragalus membranaceus (AM) is a commonly used herb in traditional Chinese medicine (TCM), which has been used as an essential tonic to treat various diseases for more than 2000 years. In this study, we aimed to investigate the biological effects of extract from AM on breast cancer cell and its mechanism. Methods: To prepare the extract, dried AM were ground and extracted with water extraction-ethanol supernatant method. Then the main isoflavones in the extract was detect by HPLC analysis. Furthermore, the anti-proliferative activity of AM extract was examined by MTT assay and morphological observation. Cell apoptosis was evaluated with flow cytometric analysis. The expressions of total and phosphorylated PI3K, GS3K beta, Akt and mTOR were determined by western blot analysis. Results: HPLC analysis demonstrated that AM extract contained with four kinds of isoflavones, campanulin, ononin, calycosin and formononetin. The MTT test and morphological observation indicated that cells proliferation of MCF-7, SK-BR-3 and MDA-MB-231 were inhibited by AM extract in a dose dependent manner. Furthermore, flow cytometric analysis displayed that after treated with 25 mu g/ml and 50 mu g/ml AM extract, apoptosis of breast cancer cells was significantly increased as compared with DMSO and blank control group (all p < 0.05). Western blot analysis found that the level of p-PI3K, p-GS3K beta, p-Akt, and p-mTOR were significantly decreased, but the level of total-mTOR was observably increased as compared with DMSO control group. Conclusions: Taken together, the inhibited cell proliferation and induced cell apoptosis effect of AM extract via PI3K/AKT/mTOR pathway confirmed the anti-tumor potential of AM. Therefore, our findings provide a new insight into anti-cancer effect of AM extract as a promising agent in breast cancer treatment.