The calcium homeostasis and cytotoxicity effect ofgamma-tocopherol on human cancer cells

• Main Authors: Jyun-Bo Lin, 林軍伯
• Other Authors: Pei-Shan Liu
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/21841978961885561721

碩士 === 東吳大學 === 微生物學系 === 94 === Vitamin E rich diets benefits are well established, to neutralize free radicals and prevent DNA damage in the body. The term vitamin E represents several structurally related compounds, each differing in their potency and molecular mechanisms. Gamma-tocopherol, the most abundant one in the food, is investigated in this study to clear its roles on calcium signaling, cell growth and death in cells, including human epithelial carcinoma (HeLa) cells, human gastric cancer (AGS) cells, and human neuroblastoma (SK-N-SH) cells. Fura-2 measurements were used for [Ca2+]i measurement, and Western Blotting for detection the level of protein in the signaling pathway. Cell proliferation and apoptosis were measured using the MTT assay, sub-G1 phase, mitochondria membrane potential, DNA laddering and caspase activation. We found a novel character of gamma-tocopherol as inducing a cytosolic calcium ([Ca2+]i) rise and blocking calcium channel in various types, including nicotinic receptors, P2X receptors, voltage-gated ion channels and calcium ionophore A23187 and ionomycin. We also found the mixture of gamma-tocopherol and bovine serum albumin will cause death of HeLa and AGS cells but not SK-N-SH cells. Similar character also observed in human serum albumin. Bovine serum albumin/gamma-tocopherol treatment resulted in increase of subG1, DNA laddering, caspase 3, and 9, but not caspase 8. The inhibitors of caspase 3, 9 but not 8 were effective to block the cytotoxicity of Bovine serum albumin/gamma-tocopherol. Differences in the percentage cell death and apoptosis were observed in different cell lines suggesting that molecular differences in these cell lines may influence the ability of Bovine serum albumin/gamma-tocopherol to induce cell death. This is the first study to demonstrate that gamma-tocopherol has some interference on [Ca2+]i and Bovine serum albumin/gamma-tocopherol has cytotoxicity to cause apoptosis.