Venkatakrishnan C D, Tewari Arun K, Moldovan Leni, Cardounel Arturo J, Zweier Jay L, Kuppusamy Periannan, Ilangovan Govindasamy
Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA.
Am J Physiol Heart Circ Physiol. 2006 Dec;291(6):H2680-91. doi: 10.1152/ajpheart.00395.2006. Epub 2006 Jun 16.
Doxorubicin (DOX) and its derivatives are used as chemotherapeutic drugs to treat cancer patients. However, production of DOX-mediated reactive oxygen species (ROS) by prolonged use of these drugs has been found to cause dilative cardiomyopathy and congestive heart failure. Thus various preventive modalities have been developed to avoid this side effect. We have found that the DOX-mediated oxidant-induced toxicity in cardiac cells could be minimized by hyperthermia-induced small heat shock protein 27 (HSP27); that is, this protein acts as an endogenous antioxidant against DOX-derived oxidants such as H(2)O(2). Heat shock-induced HSP27 was found to act as an antiapoptotic protein (reducing ROS and Bax-to-Bcl2 ratio) against DOX, and its phosphorylated isoforms stabilized F-actin remodeling in DOX-treated cardiac cells and, hence, attenuated the toxicity. Protein kinase assays and proteomic analyses suggested that higher expression of HSP27 and its phosphorylation are responsible for the protection in heat-shocked cells. Two-dimensional gel electrophoresis showed six isoforms (nonphosphorylated and phosphorylated) of HSP27. Matrix-assisted laser desorption/ionization time of flight analyses showed alpha- and beta-isoforms of HSP27, which are phosphorylated by various protein kinases. Ser(15) and Ser(85) phosphorylation of HSP27 by MAPK-assisted protein kinase 2 was found to be the key mechanism in reduction of apoptosis and facilitation of F-actin remodeling. The present study illustrates that hyperthermia protects cells from DOX-induced death through induction and phosphorylation of HSP27 and its antiapoptotic and actin-remodeling activities.
阿霉素（DOX）及其衍生物被用作化疗药物来治疗癌症患者。然而，长期使用这些药物会产生由DOX介导的活性氧（ROS），已发现这会导致扩张型心肌病和充血性心力衰竭。因此，人们开发了各种预防措施来避免这种副作用。我们发现，热诱导的小分子热休克蛋白27（HSP27）可将DOX介导的心脏细胞氧化诱导毒性降至最低；也就是说，这种蛋白质可作为一种内源性抗氧化剂，抵御DOX衍生的氧化剂，如H₂O₂。热休克诱导的HSP27被发现可作为一种抗凋亡蛋白（降低ROS和Bax与Bcl2的比率）来抵御DOX，其磷酸化异构体可稳定DOX处理的心脏细胞中的F-肌动蛋白重塑，从而减轻毒性。蛋白激酶测定和蛋白质组学分析表明，HSP27的高表达及其磷酸化作用对热休克细胞起到了保护作用。二维凝胶电泳显示了HSP27的六种异构体（非磷酸化和磷酸化）。基质辅助激光解吸/电离飞行时间分析显示了HSP27的α和β异构体，它们被各种蛋白激酶磷酸化。发现丝裂原活化蛋白激酶辅助蛋白激酶2对HSP27的Ser(15)和Ser(85)磷酸化是减少细胞凋亡和促进F-肌动蛋白重塑的关键机制。本研究表明，热疗通过诱导HSP27及其磷酸化以及其抗凋亡和肌动蛋白重塑活性，保护细胞免受DOX诱导的死亡。
