Induction of apoptosis by the extract of marine algae symbiotic fungus Chaetomium sp. in A431 human epidermoid carcinoma cells

Abstract

Fungus Chaetomium sp. is encountered as a causative agent of infections in human and it is ubiquitous in nature. Its secondary metabolite is known for having many biological activities including anti-fungal activity and toxicity in mitochondria but still remains unknown for its anti-cancer efficacy. In this study, I found that the extract of fungus Chaetomium sp. has a potentiality to inhibit A431 cell growth in a dose- and time-dependent manner. Its cytotoxicity was examined by using cell viability assay and the mechanism of growth inhibition and cell death were elucidated by either Western blot analysis or flow cytometry. The extract induces apoptotic cell death through type I death receptor pathway including the activation of Fas, caspase-3, -6, -7 and -8, and other target proteins of caspases. However, the extract did not show any effect on the mitochondria and there was no cleavage of Bid and cytochrome c release. Furthermore, the extract inhibits cell cycle progression by arresting G1/S phase and up-regulating Cdks inhibitory proteins. It also inhibits migration of the cells which was confirmed by wound-healing assay. The results suggested that the extract has a great potentiality to induce apoptosis in A431 human epidermoid carcinoma cells via both cell cycle arrest and inhibition of cell migration.