Cytotoxic Proteins from King Tuber Oyster Medicinal Mushroom, Pleurotus tuber-regium (Agaricomycetes), Sclerotium against Human MDA-MB-231 Breast Cancer Cells.

Numerous studies have reported the vast medicinal values of proteins from mushrooms. The present study aimed to investigate the potential of protein extracts from the sclerotium of Pleurotus tuber-regium (Fr.) Singer for antitumor activities against a breast cancer cell line. Protein from P. tuber-regium sclerotium was fractionated using ammonium sulphate at concentrations of 30%, 60%, and 90% and designated as PS30, PS60, and PS90, respectively. All protein extracts were assessed for cytotoxicity toward breast cancer cell line MDA-MB-231 and normal lung fibroblast cell line MRC-5 in the MTT assay. The ability of the protein extracts to inhibit cellular migration was evaluated using the antimigration assay. The most promising protein extract against MDA-MB-231 cells was PS60, with a half-maximal inhibitory concentration of 0.75 ± 0.57 μg/mL and a selectivity index of 14.00. Cytotoxicity and antimigration effects on cancer cells were best exhibited by PS60, with absolute migration capability values between 5.4142 ± 0.6916 and 5.6581 ± 0.2015 nm/h. PS60 was shown to exert cytotoxic effects associated with the induction of apoptosis and cell cycle arrest in MDA-MB-231 cells at G1/G0 and S phase. In conclusion, PS60 protein of P. tuber-regium sclerotium has good potential to be developed into a novel antitumor drug against breast cancer.