Oral and Maxillofacial Surgery Section, Chi Mei Medical Center, Tainan, Taiwan, ROC.
Oral Oncol. 2011 May;47(5):345-51. doi: 10.1016/j.oraloncology.2011.02.014. Epub 2011 Mar 25.
Arecoline is the major alkaloid of areca nut (AN) and known to induce reactive oxygen species (ROS) production and apoptosis. The metabolic sensor AMP-activated protein kinase (AMPK), activated by ROS, also regulates apoptosis. This study used several types of cells as the experimental model to analyze the roles of ROS and AMPK in arecoline-induced apoptosis. We found that arecoline dose-dependently increased intracellular ROS level, and two antioxidants, N-acetyl-L-cysteine (NAC) and glutathione, attenuated arecoline-induced apoptotic cell death. Interestingly, arecoline dose- and time-dependently inhibited rather than stimulated AMPK-Thr(172) phosphorylation, and both NAC and glutathione relieved this inhibition. The AMPK activator, 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR), also restored the phosphorylation level of AMPK-Thr(172) and attenuated apoptotic cell death under arecoline insult. In contrast, the AMPK inhibitor, compound C, and RNA interference of AMPK expression increased the cytotoxicity of arecoline. Collectively, these results suggest that arecoline may inhibit AMPK through intracellular ROS, responsible for the execution of apoptosis.
槟榔碱是槟榔的主要生物碱，已知其能诱导活性氧（ROS）的产生和细胞凋亡。代谢感受器 AMP 激活的蛋白激酶（AMPK），被 ROS 激活，也能调节细胞凋亡。本研究使用了几种类型的细胞作为实验模型，来分析 ROS 和 AMPK 在槟榔碱诱导的细胞凋亡中的作用。我们发现，槟榔碱呈剂量依赖性地增加细胞内 ROS 水平，两种抗氧化剂，N-乙酰-L-半胱氨酸（NAC）和谷胱甘肽，能减弱槟榔碱诱导的凋亡性细胞死亡。有趣的是，槟榔碱呈剂量和时间依赖性地抑制而不是刺激 AMPK-Thr(172)磷酸化，NAC 和谷胱甘肽能缓解这种抑制。AMPK 的激活剂，5-氨基咪唑-4-甲酰胺 1-β-D-呋喃核糖核苷酸（AICAR），也能恢复 AMPK-Thr(172)的磷酸化水平，并在槟榔碱损伤下减弱凋亡性细胞死亡。相反，AMPK 抑制剂，compound C，和 AMPK 表达的 RNA 干扰增加了槟榔碱的细胞毒性。总之，这些结果表明，槟榔碱可能通过细胞内 ROS 抑制 AMPK，从而导致细胞凋亡的执行。
