Grifola frondosa polysaccharides induce breast cancer cell apoptosis via the mitochondrial-dependent apoptotic pathway

Grifola frondosa, a type of food and medical fungus, has been shown to exhibit various pharmacological activities, including anticancer effects. As the most typical cancer diagnosed among female patients, breast cancer remains a huge concern threatening human health globally. In the present study, the anti-breast cancer effects of Grifola frondosa polysaccharides (GFPs) and the underlying mechanisms were investigated in MCF-7 and MDA-MB-231 cells, as well as in nude mice bearing MCF-7 tumor xenografts. GFPs exerted cytotoxic effects on the cells, as indicated by a decrease in cell viability, and an increase in the apoptototic rate, lactate dehydrogenase release and reactive oxygen species accumulation, inducing mitochondrial dysfunction. The increased expression of Bax, cleaved caspase-3 and caspase-8, and the reduced levels of B-cell lymphoma 2 (Bcl-2) and Bcl-extra large (Bcl-xL) were observed in the cells incubated with GFPs and in the tumor tissues of the mice treated with GFPs. Moreover, the GFPs significantly suppressed the phosphorylation of AKT/glycogen synthase kinase-3β and extracellular signal-regulated kinases in a time-dependent manner. Finally, the inhibition of MCF-7 tumor xenograft growth further confirmed the anti-breast cancer effects of GFPs. All these findings revealed that GFPs induced human breast cancer cell apoptosis via the mitochondrial-dependent apoptotic pathway, and provide experimental evidence to support the use of Grifola frondosa as a potential treatment for breast cancer.