Potential role of medicinal mushrooms in breast cancer treatment: Current knowledge and future perspectives

Breast cancer has become the most common invasive form of female cancer in the last few decades. Statistics show that the rate of newly diagnosed cases of breast cancer is rising every year depending on age, race, heredity, and ethnicity. The National Cancer Institute of US and mainly the Division of Cancer Control and Population Sciences (DCCPS) promote and conduct research that also identifies the economic, social, cultural, psychological, behavioral, and biological mechanisms that are potential reasons for breast cancer development. Advanced breast cancers do not respond well to therapy, and their gene expression arouses uncontrolled growth. Although estrogen-receptor (ER)-positive breast cancers respond to hormonal therapy, the treatment of ER-negative cancers is more complicated because of their ability for developing resistance to drugs. Lack of molecular targets in estrogen receptor-negative breast cancer is a major therapeutic hurdle. It has been known that NF-κB is significantly important in the processes of inflammation, cell survival, transformation, and oncogenesis, as well as in the etiology of breast cancer. A theory exists, according to which ER-negative breast cancer cells depend on NF-κB for aberrant cell proliferation and simultaneously avoid apoptosis, suggesting that NF-κB can be used as a potential molecular target in breast cancer treatment. Studies on new anticancer treatments and other medicinal substances from mushrooms have been significantly expanded in the last few years. This is mainly because they contain bioactive polymers such as polysaccharides and polysaccharide/protein complexes, secondary metabolites, and enzymes isolated from fruit bodies, mycelia, and culture broth. There are data showing the potential activity of medicinal mushrooms in breast cancer treatment. Ganoderma lucidum has shown the most significant inhibitory effect on NF-κB activity in highly invasive breast cancer cells. Other medicinal mushrooms that have also been reported to produce biologically active substances, have been tested in in vivo or in vitro, and have demonstrated breast cancer inhibitory activity are Agaricus bisporus, A. brasiliemis, Trametes versicolor, Grifola frondosa, Inonotus obliquus, Lentinus edodes, Leucoagaricus americanus, Pleurotus ostreatus, Sparassis crispa, etc.