Antiproliferative protein from the culture supernatant of Lentinula edodes C91-3 mycelia.

We purified and isolated a novel protein (LFP(91-3)A2) with antitumor effect from Lentinula edodes C(91-3) liquid mycelial culture supernatant. LFP(91-3)A2 was purified by (NH4)2SO4 precipitation, ion-exchange chromatography (DEAE-cellulose) and gel filtration chromatography (Sephacryl S-200HR). SDS-PAGE and MALDI-TOF/MS analysis Mascot search showed LFP(91-3)A2 is a new protein with apparent molecular weight of 26 kDa. The effect on tumor cell proliferation was assessed by using MTT assay in vitro, and the LFP(91-3)A2 reduced tumor cell growth obviously in a dose dependent manner (5-15 μg/mL) (p < 0.05), while it exhibited no toxic effect on normal chick embryo fibroblasts. The antiproliferative mechanism of LFP(91-3)A2 was found to be associated with inducing cell apoptosis by flow cytometry analysis and transmission electron microscopy. The LFP(91-3)A2 is a novel protein from Lentinula edodes with tumor-suppressive activity via inducing apoptosis of tumor cells without toxicity on normal cells and may be beneficial to natural products in clinical treatment.