随着我国科学家凭借对青蒿素类药物的研究获得2011年国际拉斯科临床医学大奖，青蒿素及其衍生物再度成为举世瞩目的明星分子，其中双氢青蒿素（DHA）是青蒿素的主要代谢产物和活性最强的一种衍生物。近年来，王慧研究组对青蒿素类化合物的抗肿瘤功能及机制开展了多项研究，已发现青蒿素及其衍生物对卵巢癌、肝癌的抗癌效果并探讨了其作用机制。本研究中，该组巴乾等研究人员发现，DHA能造成肿瘤细胞铁元素的缺乏、降低铁元素的吸收、干扰细胞内铁元素既有的平衡状态，且这种改变与氧化损伤无关。进一步研究发现，DHA可以降低细胞膜上的转铁蛋白受体1（TfR1）水平，通过脂筏介导的内吞作用对其进行调控，减弱了细胞对铁的吸收从而杀伤肿瘤细胞。该研究结果将为青蒿素类以及铁元素靶向类抗肿瘤药物的开发提供理论基础。
该研究课题得到了国家自然科学基金委、中国科学院和上海市科委的资助。（生物谷Bioon.com）
doi:10.1371/journal.pone.0042703
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Dihydroartemisinin Exerts Its Anticancer Activity through Depleting Cellular Iron via Transferrin Receptor-1
Qian Ba, Naiyuan Zhou, Juan Duan, Tao Chen, Miao Hao, Xinying Yang, Junyang Li, Jun Yin, Ruiai Chu, Hui Wang
Artemisinin and its main active metabolite dihydroartemisinin, clinically used antimalarial agents with low host toxicity, have recently shown potent anticancer activities in a variety of human cancer models. Although iron mediated oxidative damage is involved, the mechanisms underlying these activities remain unclear. In the current study, we found that dihydroartemisinin caused cellular iron depletion in time- and concentration-dependent manners. It decreased iron uptake and disturbed iron homeostasis in cancer cells, which were independent of oxidative damage. Moreover, dihydroartemisinin reduced the level of transferrin receptor-1 associated with cell membrane. The regulation of dihydroartemisinin to transferrin receptor-1 could be reversed by nystatin, a cholesterol-sequestering agent but not the inhibitor of clathrin-dependent endocytosis. Dihydroartemisinin also induced transferrin receptor-1 palmitoylation and colocalization with caveolin-1, suggesting a lipid rafts mediated internalization pathway was involved in the process. Also, nystatin reversed the influences of dihydroartemisinin on cell cycle and apoptosis related genes and the siRNA induced downregulation of transferrin receptor-1 decreased the sensitivity to dihydroartemisinin efficiently in the cells. These results indicate that dihydroartemisinin can counteract cancer through regulating cell-surface transferrin receptor-1 in a non-classical endocytic pathway, which may be a new action mechanism of DHA independently of oxidative damage.
