miR-34a-KLF4负反馈调控环路在肾细胞癌发生发展中的功能和机制研究

In recent years the role of microRNAs in the pathogenesis of RCC has become the focus of intense research, with the understanding that they have the potential as new diagnostic, prognostic and, ultimately, therapeutic biomarkers in RCC. We previously reported that KLF4, a zinc-finger-containing transcription factors, was specifically down-regulated or lost in RCC and significantly associated with tumor progression and prognosis. KLF4 has tumor suppressor function in RCC. Further investigations found that miR-34a was upregulated in RCC and could suppress KLF4 while overexpression of KLF4 could also suppressed miR-34a. Moreover, bioinformation analysis indicated that there were KLF4/miR-34a regulation sequences in miR-34a promoter/KLF4 mRNA 3'UTR. So we build hypothesis that miR-34a and KLF4 form a negative feedback loop to participate in RCC genesis and progression. In this project, we plan to systematically study the function of miR-34a in renal cancer, test and verify the molecular mechanism of miR-34a-KLF4 negative feedback loop, explore the function of this negative feedback loop in RCC genesis and progression, enrich the molecular biology theory and finally contribute to the prognostic and therapeutic use of miR-34a and KLF4 in RCC.

近年来，越来越多的研究表明miRNAs广泛参与了肾癌的发生、发展过程，并具备成为新的肾癌诊断和预后分子标志物及治疗靶点的潜力。我们的前期报道了锌指样转录因子KLF4在肾癌中表达减低甚至缺失并与肾癌进展及患者预后密切相关，其在肾癌中发挥抑癌基因的作用。后续研究发现miR-34a在肾癌中表达增高，并与KLF4在肾癌中的表达存在相互抑制的现象，生物信息学分析结果显示KLF4 mRNA 3'UTR及miR-34a启动子区分别存在对方的调控序列。由此我们提出miR-34a-KLF4形成负反馈调控环路参与调控肾癌的发生与发展。本项目拟通过系统研究miR-34a在肾癌中的功能，及miR-34a与KLF4之间相互抑制的机制，阐明miR-34a-KLF4负反馈调控环路的分子机制，及该负反馈环路在肾癌发生发展中的作用，丰富肾癌相关分子生物学理论，为肾癌预后评估及治疗提供新的策略和靶点。

近年来，越来越多的研究表明miRNAs广泛参与了肾癌的发生、发展过程，并具备成为新的肾癌诊断和预后分子标志物及治疗靶点的潜力。本项目基于我们的前期研究，发现miR-34a在大多数肾癌中表达增高，并与KLF4在肾癌中的表达存在相互抑制的现象。在细胞增殖、侵袭和迁移、细胞凋亡和促微血管形成等方面，证实miR-34a在肾癌中具有促癌作用。结合生物信息学分析通过荧光素酶报道实验证实miR-34a具有直接靶向抑制KLF4的能力并通过靶向KLF4发挥促癌作用。同时，过表达亦具有抑制miR-34a表达的功能，染色质免疫共沉淀实验证实KLF4具有直接靶向结合miR-34a启动子区的功能。由此阐明了miR-34a和KLF4相互抑制的负反馈调控环路的分子机制，并通过研究证实了其在肾癌中的促癌作用。丰富肾癌相关分子生物学理论，为肾癌预后评估及治疗提供新的策略和靶点。