Proteins from Lignosus tigris with selective apoptotic cytotoxicity towards MCF7 cell line and suppresses MCF7-xenograft tumor growth

• Published in: PeerJ (San Francisco, CA) CA), 2020-08, Vol.8, p.e9650-e9650, Article e9650
• Main Authors: Kong, Boon Hong, Teoh, Kean Hooi, Tan, Nget Hong, Tan, Chon Seng, Ng, Szu Ting, Fung, Shin Yee
• Format: Article
• Language: English
• Subjects: Adenocarcinoma; Alternative medicine; Analysis; Antibodies; Antioxidants; Antioxidants (Nutrients); Antitumor activity; Antitumor agents; Apoptosis; Bax protein; Bcl-2 protein; Bioactive compounds; Biochemistry; Breast cancer; Cancer; Cancer treatment; Carbohydrates; Caspase-8; Cell proliferation; Chromatography; Cold; Cultivars; Cytotoxicity; Deoxyribonuclease; Drugs and Devices; Fractionation; Growth; In vivo antitumor; Indigenous peoples; Lectins; Lignosus tigris; Lignosus tigris (Polyporaceae); Molecular weight; Mortality; Oncology; Phenols; Prostate; Proteases; Proteins; Ribonuclease; Sclerotia; Serine; Translational Medicine; Tumor cell lines; Western blotting; Xenografts
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.9650

, a recently discovered species of the unique family, has been traditionally used by the indigenous communities in Peninsular Malaysia to treat various ailments and as an alternative medicine for cancer treatment. The cultivar sclerotia (Ligno TG-K) was found to contain numerous bioactive compounds with beneficial biomedicinal properties and the sclerotial extract exhibited potent antioxidant activity. However, the anticancer property of the Ligno TG-K including in vitro and in vivo antitumor effects as well as its anticancer active compounds and the mechanisms has yet to be investigated. The cytotoxicity of the Ligno TG-K against human breast (MCF7), prostate (PC3) and lung (A549) adenocarcinoma cell lines was evaluated using MTT cytotoxicity assay. The cytotoxic mechanisms of the active high molecular weight proteins (HMWp) fraction were investigated through detection of caspases activity and apoptotic-related proteins expression by Western blotting. The in vivo antitumor activity of the isolated HMWp was examined using MCF7 mouse xenograft model. Shotgun LC-MS/MS analysis was performed to identify the proteins in the HMWp. Cold water extract of the sclerotia inhibited proliferation of MCF7, A549 and PC3 cells with IC ranged from 28.9 to 95.0 µg/mL. Bioassay guided fractionation of the extract revealed that HMWp exhibited selective cytotoxicity against MCF7 cells via induction of cellular apoptosis by the activation of extrinsic and intrinsic signaling pathways. HMWp activated expression of caspase-8 and -9 enzymes, and pro-apoptotic Bax protein whilst inhibiting expression of tumor survivor protein, Bcl-2. HMWp induced tumor-cell apoptosis and suppressed growth of tumor in MCF-7 xenograft mice. Lectins, serine proteases, RNase Gf29 and a 230NA deoxyribonuclease are the major cytotoxic proteins that accounted for 55.93% of the HMWp. The findings from this study provided scientific evidences to support the traditional use of the sclerotia for treatment of breast cancer. Several cytotoxic proteins with high abundance have been identified in the HMWp of the sclerotial extract and these proteins have potential to be developed into new anticancer agents or as adjunct cancer therapy.