Nkx2.8通过转录抑制MDR1增强膀胱癌细胞化疗敏感性及机制研究

肿瘤耐药是导致膀胱癌治疗失败的主要原因，研究增强膀胱癌化疗敏感性的方法具有极其重要的科学意义。我们前期研究发现Nkx2.8与膀胱癌的预后密切相关，且与膀胱癌患者辅助化疗的疗效密切相关；研究还发现Nkx2.8通过转录抑制TWIST1的表达而抑制膀胱癌细胞的EMT及转移能力。我们预实验发现Nkx2.8能增强膀胱癌细胞对多柔吡星及吡柔比星的敏感性，且能转录抑制MDR1基因表达，提示Nkx2.8通过转录抑制MDR1而增强膀胱癌细胞化疗敏感性，但其机制仍有待阐明。本研究拟以高表达和沉默Nkx2.8的膀胱癌细胞及膀胱癌原位动物为模型，研究Nkx2.8对膀胱癌细胞化疗药物敏感性的影响；通过染色质免疫共沉淀、启动子活性测定及p-gp蛋白活性测定等方法阐明Nkx2.8对MDR1的调控机制；通过临床标本分析Nkx2.8与MDR1的关系及临床意义，为阐明膀胱癌化疗敏感性的调控机制和确定新的治疗靶点提供科学依据。

Drug resistance is one of the main reason for the failure of bladder urothelial carcinoma treatment. It is very important to investigate how to improve chemosensitivity of bladder urothelial carcinoma. Our previous studies found Nkx2.8 is close associated with bladder urothelial carcinoma prognosis and Nkx2.8 is an useful marker for the efficiency of adjuvant chemotherapy. Nkx2.8 inhibits epithelial-mesenchymal transition by transcriptional repression of Twist1 in bladder urothelial carcinoma. Our preliminary study found that Nkx2.8 could improve chemosensitivity of bladder urothelial carcinoma cells to Doxorubicin and Pirarubicin and transcriptional repress the expression of MDR1. In the current study, we will use bladder urothelial carcinoma cells with up-regulating or down-regulating of Nkx2.8 and orthotopic animal models to demonstrate the role of Nkx2.8 in chemosensitivity of bladder urothelial carcinoma cells. We will use ChIP assay, promotor activity test and p-gp activity detection to illustrate the mechanisms of how Nkx2.8 regulating MDR1. We will also analyze the relationship between Nkx2.8 and MDR1 in clinical baldder urothelial carcinoma tissue samples and reveal the clinical significance of Nkx2.8 and MDR1. In conclusion, our study will reveal the mechanisms of chemosensitivity of bladder urothelial carcinoma and find a new therapy target for this disease.