缓激肽系统参与阿霉素心脏毒性的分子细胞学机制

Doxorubicin(DOX) is a potent and broad-spectrum antineoplastic agent in the treatment of several cancers such as solid tumer, lymphomas and leukemias. Its use, unfortunately, is limited due to its specific cardiotoxicity. Recent studies have revealed that the mechanism underling DOX-induced cardiac injury includes apoptosis of cardiomyocytes due to cardiac oxidative stress and cardiac inflammation. Our previous study also proved that the inflammatary cell infiltration is obvious in DOX treated rat. Bradykinin(BK), a active peptide of kinin group, is known to contribute in inflammatory processes. It has been demonstrated the mRNA levels of B1 receptor(B1R) of BK were increased in mice undergoing DOX-induced cardiotoxicity,while there was no significant change in B2 receptor(B2R) of BK gene expression. Cardiac dyfunction was improved in DOX treated B1R-/- mice compared to DOX treated control mice. These results indicate that B1R is detrimental in DOX cardiotoxicity. However，what kind of role of BK and its receptors play and the exact toxic mechanism still unknown. In addition, it has been found that BK also has cardioprotective effect in different forms of heart failure. Most studies attribute the beneficial effects of BK on heart to activation B2R. However, it is unknown what role that B2R plays in DOX-induced cardiotixicity. In this study, we will investigate the role and molecular mechanism(especially the role of superoxide flashes and BK-BKR-PLC-PKC signal route)of BK on acute doxorubicin-induced cardiotoxicity by combining molecular biology technique, fluorescent probe technique, pathological technique and electrophysiological techniques. This study will clarify the effect of BK signaling on DOX-induced cardiotoxicity, and give light to the discovery and development of new BK analogues preparation. This study will also enrich the toxic theory of DOX-induced cardiotoxicity.

临床应用阿霉素（DOX）常因其剂量依赖性心脏毒性受限。DOX心脏毒性的机制是氧化应激和炎症诱导的细胞凋亡。我们前期的研究发现炎症反应是DOX致心肌损伤的早期症状。敲除缓激肽（BK）B1受体（B1R）基因的小鼠，DOX所致的心肌损伤症状明显缓解，提示B1受体激活参与DOX心脏损伤的发生。但BK及B1R的作用及其参与机制未明，对B2受体（B2R）的作用也尚不清楚。因此，本研究拟采用多种技术相结合的方法，从分子、细胞和整体动物水平探讨BK及其受体亚型在DOX致心脏损伤中的的变化及作用，并从线粒体氧化应激（超氧炫的产生）的角度分析BK-BKR-PLC-PKC信号通路是否介导DOX致心肌损伤的毒性机制。这一研究可明确BK信号在DOX心脏损伤中的作用，为研制可对抗DOX心肌损伤的新型激肽类制剂提供新思路，并丰富DOX致心肌损伤的毒性机制理论，为临床合理联合用药提供实验基础。

临床应用阿霉素（DOX）常因其剂量依赖性心脏毒性受限。DOX心脏毒性的机制是氧化应激和炎症诱导的细胞凋亡。在本研究中，我们采用体内外研究相结合的方法，观察了缓激肽及其介导的NO信号通路在阿霉素急性心肌损伤中的作用。我们的研究发现，敲除缓激肽受体可明显减轻阿霉素所致的急性心肌损伤及氧化应激反应水平，可能和BK 受体通过B1/iNOS 及B2/eNOS的信号通路调节NO的产生有关。在H9C2细胞和AC16细胞，小剂量缓激肽可以通过减少ROS、MDA生成，减少LDH释放，提高SOD活性，降低MMP和减少细胞凋亡缓解DOX诱导的心肌损伤，这种保护作用是通过PI3K/Akt/NO信号通路完成的。此外，小剂量缓激肽对阿霉素所致的心室肌细胞肌小节长度和动作电位时程缩短、舒张期钙离子浓度增加、钙瞬变幅度减小以及L-型钙电流抑制均有明显的对抗作用。体外试验结果提示，小剂量缓激肽对阿霉素引起的心肌细胞损伤有一定的保护作用，这和其可抑制阿霉素所致的细胞内钙紊乱有关。体内外研究结果的差异有待进一步研究证实。对临床卵巢癌病人的研究表明，上皮性卵巢癌患者血清中NO含量较正常人为高，其卵巢组织中B1、B2、eNOS 及iNOS的表达都增加。HOE-140 和DOX联合或单独应用均可抑制卵巢癌SKOV3细胞的增殖，其机制可能和促进细胞凋亡和抑制NO产生有关。因此，缓激肽/NO信号通路可能是临床缓解阿霉素心脏毒性的潜在靶位，我们的研究可为临床缓激肽受体阻断剂和阿霉素在抗肿瘤方面的联合应用提供参考。