Fan Guo-Chang, Zhou Xiaoyang, Wang Xiaohong, Song Guojie, Qian Jiang, Nicolaou Persoulla, Chen Guoli, Ren Xiaoping, Kranias Evangelia G
Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267-0575, USA.
Circ Res. 2008 Nov 21;103(11):1270-9. doi: 10.1161/CIRCRESAHA.108.182832. Epub 2008 Oct 23.
Doxorubicin (DOX) is a widely used antitumor drug, but its application is limited because of its cardiotoxic side effects. Heat shock protein (Hsp)20 has been recently shown to protect cardiomyocytes against apoptosis, induced by ischemia/reperfusion injury or by prolonged beta-agonist stimulation. However, it is not clear whether Hsp20 would exert similar protective effects against DOX-induced cardiac injury. Actually, DOX treatment was associated with downregulation of Hsp20 in the heart. To elucidate the role of Hsp20 in DOX-triggered cardiac toxicity, Hsp20 was first overexpressed ex vivo by adenovirus-mediated gene delivery. Increased Hsp20 levels conferred higher resistance to DOX-induced cell death, compared to green fluorescent protein control. Furthermore, cardiac-specific overexpression of Hsp20 in vivo significantly ameliorated acute DOX-triggered cardiomyocyte apoptosis and animal mortality. Hsp20 transgenic mice also showed improved cardiac function and prolonged survival after chronic administration of DOX. The mechanisms underlying these beneficial effects were associated with preserved Akt phosphorylation/activity and attenuation of DOX-induced oxidative stress. Coimmunoprecipitation studies revealed an interaction between Hsp20 and phosphorylated Akt. Accordingly, BAD phosphorylation was preserved, and cleaved caspase-3 was decreased in DOX-treated Hsp20 transgenic hearts, consistent with the antiapoptotic effects of Hsp20. Parallel ex vivo experiments showed that either infection with a dominant-negative Akt adenovirus or preincubation of cardiomyocytes with the phosphatidylinositol 3-kinase inhibitors significantly attenuated the protective effects of Hsp20. Taken together, our findings indicate that overexpression of Hsp20 inhibits DOX-triggered cardiac injury, and these beneficial effects appear to be dependent on Akt activation. Thus, Hsp20 may constitute a new therapeutic target in ameliorating the cardiotoxic effects of DOX treatment in cancer patients.
阿霉素（DOX）是一种广泛使用的抗肿瘤药物，但其应用因心脏毒性副作用而受到限制。热休克蛋白（Hsp）20最近已被证明可保护心肌细胞免受缺血/再灌注损伤或长期β-激动剂刺激诱导的细胞凋亡。然而，尚不清楚Hsp20是否会对DOX诱导的心脏损伤发挥类似的保护作用。实际上，DOX治疗与心脏中Hsp20的下调有关。为了阐明Hsp20在DOX引发的心脏毒性中的作用，首先通过腺病毒介导的基因传递在体外使Hsp20过表达。与绿色荧光蛋白对照相比，Hsp20水平升高赋予对DOX诱导的细胞死亡更高的抗性。此外，体内心脏特异性过表达Hsp20可显著改善急性DOX引发的心肌细胞凋亡和动物死亡率。Hsp20转基因小鼠在长期给予DOX后还表现出心脏功能改善和生存期延长。这些有益作用的潜在机制与Akt磷酸化/活性的保留以及DOX诱导的氧化应激的减轻有关。免疫共沉淀研究揭示了Hsp20与磷酸化Akt之间的相互作用。因此，在DOX处理的Hsp20转基因心脏中，BAD磷酸化得以保留，而裂解的caspase-3减少，这与Hsp20的抗凋亡作用一致。平行的体外实验表明，感染显性负性Akt腺病毒或用磷脂酰肌醇3-激酶抑制剂预孵育心肌细胞均显著减弱了Hsp20的保护作用。综上所述，我们的研究结果表明，Hsp20的过表达可抑制DOX引发的心脏损伤，且这些有益作用似乎依赖于Akt激活。因此，Hsp20可能构成改善癌症患者DOX治疗心脏毒性作用的新治疗靶点。
