RUNX3基因通过FAK抑制肾癌转移的分子机制研究

Matastasis is the leading cause of death for renal cell carcinoma patients. RUNX3 was identified as a tumor suppressor gene. In our previous study, we identified that forced expression of RUNX3 drastically inhibited renal cancer cell invasion and tube formation of HUVECs. However, the underlying molecular mechanism in not clear. It is demonstrated that FAK is an important regulator of cell adhesion, motility and metastasis. In our preliminary experiment, we found that si-FAK suppressed renal cell invasion and tube formation of HUVECs. RUNX3 overexpression decreased mRNA and protein level of FAK. Moreover, the biological information software predicted that there were four potential RUNX3 binding sites in the FAK promoter. Consequently, we suppose that RUNX3 may regulate renal cell carcinoma metastasis through inhibiting FAK transcriptional expression by binding with FAK promoter. To confirm this hypothesis, we will investigate the effect of RUNX3 on FAK transcriptional expression, and verify the binding sites in the FAK promoter by EMSA, ChIP and site mutation. Then, we will explore the effect of RUNX3 on metastatic biological behavior through FAK. Lastly, we will examine the correlation between the RUNX3, FAK expression and metastasis by 271 cases tissue microarray. Our study will provide evidence for new therapeutic target for renal cell carcinoma.

转移是肾癌患者死亡主要原因。RUNX3是一抑癌基因，我们既往研究发现RUNX3过表达可以抑制肾癌细胞侵袭能力。但是发挥这一作用的具体机制尚不清楚。FAK是调节细胞粘附、运动、转移的关键因子。申请者预实验发现，RUNX3能够抑制FAK表达；下调FAK表达可以抑制肾癌细胞侵袭和脐静脉内皮细胞血管形成。生物信息分析发现，FAK启动子区有4个潜在的RUNX3结合位点。 因此，本课题提出"RUNX3通过与FAK启动子结合抑制FAK转录影响肾癌转移" 。为证明这一假说，我们将在分子水平研究RUNX3与FAK启动子的结合，确认其结合位点，以及对FAK转录的影响；然后在细胞水平研究RUNX3通过FAK对肾癌细胞转移相关生物学行为的影响；最后通过肾癌组织芯片研究RUNX3、FAK表达与肾癌转移的关系。为寻找肾癌新的治疗靶点提供实验依据。

Runt相关转录因子-3（RUNX3）在实体瘤中发挥抑癌基因的作用。但是，RUNX3在肾癌中的作用还不清楚。因此，我们主要探讨RUNX3在肾癌转移中的作用及潜在的作用机制。我们首先利用肾癌组织芯片研究RUNX3在肾癌组织中的表达，结果分析发现与癌旁正常肾组织相比RUNX3在肾癌组织中表达降低（P<0.001）；与TNM分期I期肾癌组织相比，II-IV期肾癌组织中RUNX3表达降低（P<0.001）；与pT1分期肾癌组织相比，pT2-4分期肾癌组织中RUNX3表达降低（P<0.001）。RUNX3的低表达与患者的不良预后密切相关，并可以作为预后因子判断肾癌的预后。RUNX3可以通过促进E钙粘蛋白的表达抑制肾癌细胞的迁移侵袭从而发挥抑制肾癌转移的作用。我们进一步研究发现，RUNX3可以通过与microRNA-6780a-5p启动子区结合抑制其表达，同时证实E-cadherin是microRNA-6780a-5p的直接靶基因。因此，RUNX3可以通过靶向miR-6780a-5p/E-cadherin信号抑制肾癌细胞的迁移侵袭能力。这条通路阐明了RUNX3发挥抑制肾癌转移的新的作用机制，为肾癌的治疗提供了潜在靶点。