华人科学家发现青蒿素的选择性抗癌作用

　　

生物通报道：来自华盛顿大学生物工程学系的华裔科学家Henry Lai一直致力于青蒿素（artemisinin）的研究，日前他和另一位华盛顿大学的同事Narendra P. Singh在之前研究的基础上发现了青蒿素能选择性的对抗癌症细胞，通过口服的方式明显抑制乳腺癌的发生。这一研究结果作为快讯刊登在12月的Cancer杂志上。

青蒿素是一种新型的抗疟天然药物，存在于苦艾中。在古时候的亚洲，人们就已经知道用苦艾来治疗疟疾。这种药物具有低毒、高效、速效的特点，对恶性疟、间日疟都有效，可用于凶险型疟疾的抢救和抗氯喹病例的治疗。这种物质能够治疗疟疾是因为当它与铁离子接触的时候，就会诱发一系列的化学反应，使细胞内形成高活性的化学物质作用于细胞膜使其结构改变，从而杀伤细胞。疟原虫吞噬了这种储存变性铁离子的血细胞后就会死亡。

这一作用在对抗癌细胞时也同样有效：在癌细胞迅速复制增殖的过程中，大部分都需要大量的铁离子（作为转运受体），这样具有许多铁离子转运载体的癌细胞就成为了青蒿素选择性攻击的对象。在这项研究中，研究人员给大鼠口服致癌剂（7,12-dimethylbenz[a]anthracene，一种已知的可引发复合乳腺癌的试剂），然后给其中作为对照组的一组正常喂养，另一实验组则施用一定剂量的青蒿素。经过40周的培养，研究人员发现对照组96％的大鼠产生肿瘤，而实验组只有57％的大鼠产生肿瘤，并且产生肿瘤的数量和体积均明显小于对照组。

对此研究人员认为可以有两种解释：一是青蒿素在肿瘤形成前就可以杀死需要比正常细胞更多铁离子的癌症前期细胞；另一个原因则可能是阻止癌细胞血管生成（angiogenesis）。这一研究说明了青蒿素的有效抑乳腺癌发生的作用，进一步研究也许可以发现青蒿素对于其它类型的癌症同样有效。（生物通记者：张迪）

Henry Lai简介：

研究方向：
Medical Imaging & Image-Guided Therapy

教育经历：
Ph.D. (psychology), University of Washington, 1978
  
研究兴趣：
    •  Biological effects of electromagnetic fields
    •  Cancer treatment using artemisinin and synthetic compounds

主要论著：
Lai, H. Research on the neurological effects of nonionizing radiation at the University of Washington. Bioelectromagnetics 13:513-526, 1992.
Lai, H. Neurological effects of microwave irradiation. In: Advances in Electro-magnetic Fields in Living Systems (Vol. 1), J.C. Lin (ed.), Plenum Press, New York, 1994.
Lai, H. and Singh, N.P. Selective cancer cell cytotoxicity from exposure to dihydroartemisinin and holotransferrin. Cancer Letters 91:41-46, 1995.
Chandos, B., Khan, A., Lai, H. and Lin, J.C. The application of electromagnetic energy to the treatment of neurological and psychiatric diseases. In: Biological Effects of Magnetic and Electromagnetic Fields, E. Ueno (ed.), Plenum Press, New York, 1996, pp. 161-169.
Lai, H. and Sigh, N.P. DNA single- and double- strand DNA breaks in rat brain cells after acute exposure to low-level radiofrequency electromagnetic radiation. Int. J. Radiat. Biol. 69:513-521, 1996.
Lai, H. Spatial learning deficit in the rat after exposure to a 60 Hz magnetic field. Bioelectromagnetics. 17:494-496,1996.
Feagin, J.E., Wurscher, M.A., Ramon, C. and Lai, H. Magnetic fields and malaria. In "Biologic Effects of Light: Proceedings of the Biologic Effects of Light Symposium" Holick, M.F. and Jung, E. G. (eds.), Kluwer Academic Publishers, Hingham, MA, 1999, pp. 343-349.
Lai, H. Biological effects of radiofrequency radiation from wireless transmission towers. In "Cell Towers: Wireless Convenience? Or Environmental Hazard?" Levitt, B.B. (ed.), New Century Publishing, East Canaan, CT, 2001, pp. 65-74.
Singh, N.P. and Lai, H. Selective toxicity of dehydroartemisinin and holotransferrin on human breast cancer cells. Life Sciences 70:49-56, 2001.
Lai, H. and Singh N.P. Magnetic field-induced DNA strand breaks in brain cells of the rat. Environmental Health Perspectives 112:687-694, 2004.
Singh N.P. and Lai H. Artemisinin induces apoptosis in human cancer cells. Anticancer Research 24:2277-2280, 2004.
Lai, H. Interaction of microwaves and a temporally incoherent magnetic field on spatial learning in the rat. Physiology and Behavior 82:785-789, 2004.
Lai, H., Sasaki, T., Singh, N.P., and Messay, A. Effects of artemisinin-tagged holotransferrin on cancer cells. Life Sciences 76:1267-1279, 2005.
Lai, H and Singh, N.P. Oral artemisinin prevents and delays the development of 7, 12-dimethylbenz(a)anthracene (DMBA)-induced breast cancer in the rat. Cancer Letters (In press)