心脏特异信号分子CARP拮抗阿霉素诱导的心肌损伤作用及机制

Doxorubicin (DOX; also known as adriamycin) is among the most effective and widely used anticancer drugs in the clinic. However, its clinical use is limited by the risk of myocaedial injury. Cardiac adriamycin responsive protein (CARP) is a heart specific protein, which expression is inhibited by DOX. Our preliminary data showed that the mortality was significantly increased and shorter survival time in CARP knockout (CARP-KO) mice compared to wild type (WT) mice. It also found that CARP increased peroxisome proliferator-activated receptor-γ coactivador-1α (PGC-1α) expression, the key regulator for mitochondrion biogenesis, and inhibited apoptosis-related transcription factor TA p63γ. Therefore, we speculate, DOX down-regulates CARP leading to reduced PGC-1α gene expression and liberates TA p63 γ, both of which result in increased cardiac damage. Decreased expression of PGC-1α exacerbates impairment of mitochondrial functions by augmenting oxidative stress in cardiac cells and increased activity of TA p63γ triggers apoptosis in myocardial cells. In this study, we used WT, transgenic cardiac-specific CARP overexpressing (CARP-TG) and CARP-KO mice, and the corresponding primary cultured cardiomyocytes to investigate the roles of CARP in cardiomyopathy induced by DOX. We will provide several lines of evidence indicating that CARP is the target for DOX-induced cardiac damage and a novel therapeutic strategy for DOX clinical applications based on the regulatory mechanisms of CARP expression.

阿霉素（DOX）是高效、广谱的抗肿瘤药物，但因其心肌损伤性限制了临床应用。心脏阿霉素反应蛋白（CARP）是被DOX抑制的心脏特异性表达蛋白。我们前期研究发现，DOX给药的CARP敲除小鼠比野生型小鼠生存时间更短，生存率更低。此外，还发现CARP可以上调线粒体生成关键因子PGC-1α的表达，并抑制细胞凋亡相关转录因子TA p63γ的活性。因此我们推测：DOX下调CARP的表达，可能主要从两个途径引发心肌损伤：一方面降低了PGC-1α表达影响线粒体生成与功能，使活性氧无法有效清除造成了心肌氧化应激损伤；另一方面解除了对TA p63γ活性的抑制，诱导心肌细胞凋亡。本课题将利用CARP心脏特异性转基因及基因敲除小鼠，在动物、细胞及分子水平研究CARP对DOX心肌损伤的保护作用及机制。本研究将增进我们对DOX心肌损伤产生机制的理解，为防治DOX心肌损伤提供新的靶点和理论依据。

研究背景：阿霉素（Doxorubicin, DOX）是临床应用最广泛的抗肿瘤药物。但 DOX 会诱导心脏损伤，严重限制了DOX 的临床应用。寻找阻断 DOX 心肌损伤的分子靶点，对于开发安全有效的预防 DOX 心肌损伤药物有重要意义。我们前期发现，心脏阿霉素反应蛋白（CARP）作为DOX抑制的心肌特异表达的蛋白，可能在DOX 所致心肌损伤中起到核心调控作用。.本项目的主要研究内容包括：1.在细胞和动物水平明确 CARP对 DOX 心肌损伤的保护作用；2.在分子水平分析 CARP 通过激活PGC-1α和抑制TA p63γ的转录活性，分别调控线粒体生物合成、 ROS 清除以及拮抗心肌细胞凋亡作用，进而发挥对 DOX 诱导的心肌损伤的保护作用。.通过以上研究，主要获得的结果有：CARP可有效保护DOX诱导的心肌损伤；2.CARP通过激活激活PGC-1α促进线粒体生成及ROS清除；3.CARP通过降低 TA p63γ的转录活性，有效阻止细胞凋亡；4. 改变CARP的表达水平可一定程度降低DOX诱导的心肌细胞损伤。.我们的结果提示CARP作为心肌特异表达的信号分子，并可通过调控PGC-1α和TA p63γ的表达及活性影响线粒体生成和细胞凋亡，进而拮抗DOX引发的心肌细胞损伤。本项目研究为心肌损伤治疗提供了理论依据，为降低阿霉素心肌损伤研究开拓了新的分子靶点，提高CARP的表达有助于降低DOX诱导的心肌损伤的发生。