Immunomodulatory Effect and an Intervention of TNF Signalling Leading to Apoptotic and Cell Cycle Arrest on ORL-204 Oral Cancer Cells by Tiger Milk Mushroom, Lignosus rhinocerus

Abstract

Research background. Tiger milk mushroom (Lignosus rhinocerus) is a medicinal mushroom that is geographically distributed in the region of South China, Thailand, Malaysia, Indonesia, Philippines and Papua New Guinea. Consumption of its sclerotium has been reported to treat various ailments. However, its anticancer potential towards oral cancer cell lines is yet to be discovered considering its traditional method of consumption by biting/chewing of the sclerotium. Experimental approach. Mushroom sclerotial powder of cultivar TM02® was extracted and fractionated by a Sephadex G-50 chromatographic column prior to cytotoxicity testing against a panel of human oral cancer cell lines. The capability of the identified bioactive fraction in regulating several molecules associated with its TNF pathway was investigated. Results and conclusions. MTT proliferation assay indicated that ORL-48 (derived from gingiva), ORL-188 (derived from the tongue), and ORL-204 (derived from buccal mucosa) were inhibited by L. rhinocerus sclerotial cold water extract and its high-molecular-mass fraction (HMM) in varying degree with ORL-204 being most affected. Hence, HMM treatment on ORL-204 was further investigated. HMM induced apoptosis and G0/G1-phase cell cycle arrest through caspase-3/7 cleavage. Activities of MIP2 and COX-2 were downregulated by 0.2- and 4.6-fold respectively in the HMM-treated ORL-204 cells. Novelty and scientific contribution. Using ORL-204, it revealed that HMM may have intervened via the TNF pathway at various network sites in its manifestation as a potential dietary compound for cancer prevention and natural adjunct therapeutic to conventional cancer treatment.