Anti-tumor effects and mechanisms of Astragalus membranaceus (AM) and its specific immunopotentiation: Status and prospect

With cancer deaths increasing, the initiation, pathophysiology and curative management of cancer is receiving increasing attention. Traditional therapies such as surgery and chemoradiotherapy are often accompanied by suppression of host immunity, which increase the risk of metastasis. Astragalus membranceus (AM) is commonly utilized as one herbal medicine of traditional Chinese medicines (TCMs) with a variety of biological activities. Studies have shown that the active ingredients of AM and AM-based TCMs, combined with chemotherapy, can enhance anti-tumor efficacy in cancer patients, in addition to reduce complications and avoid side effects induced by chemotherapy. By using various cancer models and cell lines, AM has been found to be capable of shrinking or stabilizing tumors by direct anti-proliferation or pro-apoptosis effect on tumor cells. Further, AM ameliorates immunosuppression by activating M1 macrophages and T cells tumor-kill function in tumor microenvironment (TME). AM is also found to improve systemic immunity which may help promoting efficacy of chemotherapy and preventing metastasis. Thereby this review contributes to an understanding of AM as an adjunctive therapy in the whole course of cancer treatment, at the same time providing useful information for development of more effective anti-tumor medication. The combination of AM and immune checkpoint therapies has a promising therapeutic prospect, and the observation of direct efficacy and mechanisms on tumor growth and metastasis of AM combined with chemotherapies or other therapies require more in vivo validations and further clinical investigation as well.