Jiang Jiangsong, Mohan Nishant, Endo Yukinori, Shen Yi, Wu Wen Jin
Division of Biotechnology Research and Review I, Office of Biotechnology Products, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, MD, USA.
Oncotarget. 2017 Dec 21;9(5):6095-6108. doi: 10.18632/oncotarget.23543. eCollection 2018 Jan 19.
Despite heightened risk of cardiotoxicity associated with combination therapy of anthracyclines and trastuzumab in HER2-positive breast cancer patients, little research effort has been invested in exploring the molecular mechanisms of cardiotoxicity induced by this combination therapy. In this study, we demonstrate that trastuzumab downregulates both gene and protein expressions of type IIB DNA topoisomerase/DNA topoisomerase IIB (TOP2B), a major intracellular target mediating doxorubicin-induced cardiotoxicity, in human primary cardiomyocytes. This in turn induces DNA damage activity and DNA double strand breaks, which is indicated by the enhanced phosphorylation of H2AX (γH2AX) and ataxia telangiectasia and Rad3-related protein (ATR pS428) in trastuzumab-treated cardiomyocytes. Furthermore, concurrent or sequential treatment of doxorubicin and trastuzumab significantly increases the downregulation of the protein levels of TOP2B, enhances apoptosis and cell growth inhibition, and promotes production of reactive oxidative and nitrative species in human cardiomyocytes as compared to either trastuzumab or doxorubicin treatment, indicating augmentation of cardiotoxicity in combination therapy. Additionally, our data reveal that doxorubicin treatment increases the levels of ErbB2/HER2 expression in human cardiomyocytes as compared with that in cells not treated with doxorubicin, leading to the enhanced activity downstream of HER2 signaling. Consequently, this may render the cardiomyocytes to become addicted to HER2 signaling for survival under stressed conditions. Enhanced HER2 protein expression leaves cardiomyocytes more sensitive to trastuzumab treatment after doxorubicin exposure. This study provides molecular basis for significantly increased cardiotoxicity in cancer patients who are treated with anthracyclines and trastuzumab-based combination regimens.
尽管在HER2阳性乳腺癌患者中，蒽环类药物与曲妥珠单抗联合治疗存在较高的心脏毒性风险，但在探索这种联合治疗所致心脏毒性的分子机制方面投入的研究精力很少。在本研究中，我们证明曲妥珠单抗可下调人原代心肌细胞中IIB型DNA拓扑异构酶/DNA拓扑异构酶IIB（TOP2B）的基因和蛋白表达，TOP2B是介导阿霉素诱导心脏毒性的主要细胞内靶点。这反过来会诱导DNA损伤活性和DNA双链断裂，这在曲妥珠单抗处理的心肌细胞中表现为H2AX（γH2AX）和共济失调毛细血管扩张症及Rad3相关蛋白（ATR pS428）磷酸化增强。此外，与单独使用曲妥珠单抗或阿霉素治疗相比，阿霉素与曲妥珠单抗同时或序贯治疗显著增加TOP2B蛋白水平的下调，增强细胞凋亡和细胞生长抑制，并促进人心肌细胞中活性氧化和硝化物质的产生，表明联合治疗中心脏毒性增强。此外，我们的数据显示，与未用阿霉素处理的细胞相比，阿霉素处理可增加人心肌细胞中ErbB2/HER2的表达水平，导致HER2信号下游活性增强。因此，这可能使心肌细胞在应激条件下对HER2信号产生生存依赖。阿霉素暴露后HER2蛋白表达增强使心肌细胞对曲妥珠单抗治疗更敏感。本研究为接受蒽环类药物和基于曲妥珠单抗的联合治疗方案的癌症患者心脏毒性显著增加提供了分子基础。
