Toxicity of areca nut ingredients: Activation of CHK1/CHK2, induction of cell cycle arrest, and regulation of MMP-9 and TIMPs production in SAS epithelial cells

Background. There are 600 million betel quid chewers around the world. betel quid chewing is a major risk factor of oral cancer. Why betel quid components induce oral cancer is not clear. Methods. Cytotoxicity of areca nut extract and arecoline (an areca nut alkaloid) to SAS oral epithelial cell line was evaluated by trypan blue dye exclusion and MTT assays. Cell cycle distribution and apoptosis was analyzed by propidium iodide staining flow cytometry. Chk1 and chk2 activation was analyzed by Pathscan phospho-enzyme-linked immunosorbent assay. Metalloproteinase-9 (MMP-9), tissue inhibitors of metalloproteinase (TIMPs) production was measured by enzyme-linked immunosorbent assay. Results. Areca nut extract (800 mu g/mL) and arecoline (>0.4 mmol/L) caused cell death, apoptosis, and cell cycle arrest of SAS cells. Areca nut extract and arecoline stimulated Chk1 and Chk2 phosphorylation in SAS cells. Areca nut extract stimulated cellular MMP-9 but suppressed TIMP-1 and TIMP-2 production. Conclusions. Areca nut components activate Chk1/Chk2, alter cell cycle regulation/apoptosis, MMP-9, and TIMPs production, contributing to the pathogenesis of oral carcinogenesis. (C) 2012 Wiley Periodicals, Inc. Head Neck 35: 1295-1302, 201