OXIDATIVE STRESS INDUCED G1/S PHASE CELL CYCLE ARREST AND CELLULAR APOPTOSIS IN CULTURED BUCCAL KB EPITHELIAL CELLS ON EXPOSURE OF AQUEOUS EXTRACT OF ARECA NUT

Author(s): Rashmi Nagesh, Kiran Kumar K. M, Naveen Kumar M, S. Chidananda Sharma and M. Sreepriya

Abstract: Areca nut chewing is often associated with incidence of severe oral cancer, leukoplakia and oral submucous fibrosis (OSF). Areca nut and its components are the major etiological factors that are responsible for the causation of oral cancers. Although there exist numerous evidences on harmful effects of areca nut chewing, the present study shows the effect of aqueous extract of areca nut on human buccal KB epithelial cells on growth and viability followed by biochemical analysis of oxidant and anti-oxidant levels that are known to alter the cell cycle progression. Buccal KB cells on treatment with aqueous areca nut extract showed reduced viability by 48 h with IC50 value of 0.35 %. Areca nut extract induced the production of reactive oxygen species (ROS) which in turn react with lipid moiety on plasma membrane and cause loss of membrane integrity with leakage of lactate dehydrogenase enzyme into culture supernatant. The excessive production of oxidants with decreased antioxidant levels of superoxide dismutase (SOD) and glutathione S transferase (GST) which leads to altered redox homeostasis. Further, the results of cell cycle analysis by flow cytometry showed G1/S phase cell cycle arrest on extract exposure. Additionally, annexin V FITC/PI staining was carried out to assess cellular apoptosis on exposure of areca nut extract which showed induction of apoptosis by 48 h. Hence, the present study helps in better understanding the role of oxidative stress in altering cell cycle progression and apoptosis pathway in aqueous areca nut extract treated KB cells.

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