汉防己甲素(Tetrandrine)诱导肝癌细胞自噬在肿瘤治疗中的作用研究

Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the broadly used Chinese medicinal herb Stephaniae tetrandrae, exhibits potent effects on treating inflammation, analgesia, hepatic fibrosis and even silicosis. Recently, its potential to be used as a cancer chemotherapeutic agent has aroused widespread concerns. We previously reported that a higher concentration of tetrandrine (30 μM) induce ROS/Akt mediated apoptosis in liver cancer cells in vitro and in vivo. In this project, we found that lower dose of tetrandrine (5 μM) has little effect on liver cancer cell viability but can prominently promote liver cancer cell autophagy by activating MAPK protein family member ERK, p38 and autophagic associated gene (Atg) protein family members Atg-5 and Atg-7 activities respectively. However it is unclear currently that the function of autophagy-inducing effect of tetrandrine and its anticancer application. With the basis of our previous investigation, we will further our project on aspects about unraveling the exact molecular mechanism of tetrandrine's autophagic inducing effect on hepatocellular carcinoma, displaying the relationship between tetrandrine induced autophagy and apoptosis and, finally, demonstrating the function of autophagy on tumorigenesis and its application on cancer treatment. We confidently believe that our research results will contribute to the development and clinical application of tetrandrine in modern medicine community and will provide the academic grounds for designing novel anticancer drugs with low cytotoxicity.

汉防己甲素是从中草药中提取一种双苄基异喹啉类生物碱，在消炎、镇痛、肝纤维化和硒肺等方面都有较好疗效。近年来其抗肿瘤活性引起了人们的极大关注。我们研究发现较高浓度的汉防己甲素（30 μM）在体内、体外可通过激活ROS/Akt信号通路诱导肝癌细胞凋亡（Int J Cancer, 2011）。本项目研究发现，较低浓度的汉防己甲素（5 μM）不影响细胞存活，但能显著诱导肝癌细胞自噬，激活胞内部分MAPK（ERK和p38）激酶活性，促进自噬相关基因Atg-5和Atg-7的蛋白表达水平，但汉防己甲素诱导肝癌细胞自噬在其抗肿瘤治疗中的作用仍不清楚，本项目将在现有工作基础之上，研究汉防己甲素诱导肝癌细胞自噬的分子机理，阐述诱导癌细胞自噬与凋亡的关系，揭示细胞自噬对肿瘤生存的作用及其在抗肿瘤治疗中的意义，研究结果将为汉防己甲素在现代医学中的进一步开发应用、研制新的高效低毒的抗癌药物提供理论依据。

汉防己甲素是从传统中药粉防己的块根中提取出的一种双苄基异喹啉类生物碱，具有显著的抗肿瘤活性并且具有成为肿瘤化疗药物的潜力。本项目中我们研究发现，低浓度的汉防己甲素(5 μM) 处理人类肝癌细胞可以诱导LC3-Ⅱ的表达，酸性自噬溶酶体空泡（AVOs）形成和GFP-LC3融合蛋白发生荧光点聚集，这些表明细胞自噬的发生。汉防己甲素诱导了细胞内活性氧簇（ROS）的产生，使用活性氧清除剂处理可以显著消除由汉防己甲素诱导产生的自噬。这些结果表明活性氧的产生在促进汉防己甲素诱导的自噬中扮演着重要的角色。汉防己甲素通过引起线粒体功能紊乱导致活性氧的累积和自噬的发生。同时，活性氧产生激活了ERK MAP激酶， ERK信号通路至少部分导致了汉防己甲素在肝癌细胞中诱导的自噬。此外，我们还发现汉防己甲素可以在转录水平上调控自噬相关基因7（ATG7）的表达，这也促进了汉防己甲素诱导的自噬。除了体外研究，我们在体内研究也观察到类似结果，肿瘤异种移植模型中汉防己甲素处理导致ROS累积并且诱导细胞自噬。有趣的是，汉防己甲素在秀丽隐杆线虫肌肉细胞中也以一种ROS依赖的方式诱导了自噬。因此，这些研究表明，汉防己甲素是一个强有力的细胞自噬激动剂，并且很可能成为一个有前途的临床化疗药物。