BRD4诱导的EMT在NSCLC厄洛替尼耐药中作用及机制研究

Bromodomain-containing protein 4 (BRD4), which can specifically recognize and bind to acetylated lysine residues of chromatin histone H3/H4, plays an important role in the process of tumor occurrence and development. At present, whether BRD4 is involved in erlotinib resistance has not been reported. It has been increasingly recognized that epithelial mesenchymal transition (EMT) are critically implicated in erlotinib resistance. Our preliminary study identified signs of EMT in tumor tissues derived from nine cases of NSCLC patients who developed acquired resistance to erlotinib, including downregulated E-cadherin. BRD4 inhibitor combined with erlotinib showed synergistic effects in NSCLC erlotinib-resistant cell lines, and reduced E3 ubiquitin ligase MDM2, increased E-cadherin, but the exact mechanism remained unclear. Using gene transfection, shRNA technology, ChIP and orthotopic lung cancer model in mice, we explore the internal relations between BRD4, MDM2 and EMT, erlotinib resistance, and try to demonstrate the molecular mechanisms of BRD4 inhibitor to reverse erlotinib resistance. Our proposal will be validated in bioluminescent orthotopic NSCLC mouse model as well as in NSCLC patients. This reseach will provide new ideas and new approaches to treat erlotinib resistance.

溴区包含蛋白4（BRD4）能够特异性识别并结合染色质组蛋白H3/H4乙酰化赖氨酸残基，在肿瘤发生发展过程中起重要作用。目前，关于它是否参与了厄罗替尼的耐药尚未见报道。近年来，上皮-间质转化（EMT）在厄洛替尼耐药中的作用日益受到重视。我们前期研究发现：在9例产生厄洛替尼获得性耐药的非小细胞肺癌（NSCLC）患者的癌组织中，EMT标志蛋白E-cadherin表达降低。BRD4抑制剂联合厄洛替尼在NSCLC厄洛替尼耐药株存在协同作用，下调E3泛素连接酶MDM2，上调E-cadherin，但具体机制不明。本研究拟采用基因转染、shRNA技术、ChIP、小鼠生物发光NSCLC原位移植瘤模型等技术，研究BRD4、MDM2与EMT、厄洛替尼耐药性的内在联系，探讨BRD4抑制剂逆转厄洛替尼耐药的分子机制，最后在动物水平和NSCLC患者中进行验证，拟为临床治疗厄洛替尼耐药提供新思路和新途径。

溴区包含蛋白4（BRD4）能够特异性识别并结合染色质组蛋白H3/H4乙酰化赖氨酸残基，在肿瘤发生发展过程中起重要作用。我们前期研究发现BRD4抑制剂联合厄洛替尼在NSCLC厄洛替尼耐药株存在协同作用。本项目重点研究了BRD4抑制剂对NSCLC抗肿瘤作用及其分子机制，发现BRD4抑制剂通过下调eIF4E和Met，上调FoxO1，抑制厄洛替尼敏感和耐药NSCLC细胞株和小鼠原位移植瘤生长，过表达或抑制eIF4E会影响BRD4抑制剂的抗肿瘤作用。本项目扩展研究发现，在小鼠奥沙利铂化疗致周围神经病变(CIPN)模型中，BRD4抑制剂JQ1通过抑制MMP-2/9酶活性，下调MMP-2/9基因表达，改善CIPN症状。本研究阐明了BRD4抑制剂的抗肿瘤和改善CIPN的分子作用机制，为临床治疗NSCLC和CIPN提供新思路和新途径。