The induction and mechanism of autophagic cell death by a partially purified fraction of areca nut extract.

• Main Authors: Ya-yun Shih, 施雅云
• Other Authors: 林美惠
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/70305780636575996467

碩士 === 嘉南藥理科技大學 === 生物科技研究所 === 95 === Betel quid (BQ) and areca nut (AN) are both recognized as carcinogens, however, the effects of their ingredients on cells are not poorly studied. We have previously found that extract of AN (ANE) induce an autophagy-like cell death as evidenced by swollen cell morphology and LC3-II activation. In this study, we further addressed that the autophagy-inducing activity of ANE is located between 30-100 kDa (designated as LLS-2). Treatment of LLS-2 results in the dose-dependent activation of LC3-II, which peaked at 24 hr. Furthermore, it also induces the emergence of acidic vacuoles (by acridine orange staining), autophagic vacuoles (by transmission electron microscopy), and swollen cells with the condensed nucleus and nearly empty cytoplasm (by transmission electron microscopy and hematoxylin and eosin staining). On the other hand, arecoline (Are) triggers the caspase-3 activation, DNA fragmentation, and condensed and micronucleated nuclei. Both 3-MA and NH4Cl inhibit the cytotoxicity of arecoline, while only 3-MA exhibits more blocking effect on LLS-2-mediated cytotoxicity than that of NH4Cl. ANE, Are and LLS-2 activates the phosphorylation of ERK1/2 and S6K-Thr389, whereas only ANE and LLS-2 inhibit the phosphorylation of mTOR-Ser2448 after 24-hr treatment. Taken together we conclude that Are and LLS-2 induce apoptosis and autophagy, respectively. LLS-2 may represent a brand-new autophagy-inducing AN ingredient, which acts through the inhibition of mTOR pathway.