调控ZEB的长非编码RNA（lncRNA）ZEBAS的功能及其在前列腺癌中的作用

Members of the transcription factor ZEB family play crucial roles in tumorigenesis and tumor progression. We identified a novel group of long noncoding RNAs (lncRNAs), which we named ZEBAS. Based on preliminary experiments, we propose that ZEBAS may epigenetically and transcriptionally regulate ZEB, which in turn may control the transcription of its target genes such as HRK of the apoptosis-regulatory molecules. Deregulation of the ZEBAS-ZEB-target gene axis may be an important mechanism of prostate cancer pathogenesis. Potential mechanisms of ZEB regulation by ZEBAS include (1) histone modification mediated by its binding to or recruiting of histone modifying factors or co-factors; (2) inhibition of ZEB promoter methylation by competitive binding of ZEBAS to DNA methyltransferase; (3) promotion of ZEB transcription by ZEBAS binding to or recruiting of such transcription factors as NFkB. This project aims to elucidate the molecular mechanisms for regulation of ZEBAS-ZEB-target gene axis, and the roles of its dysfunction in prostate cancer.

转录因子ZEB家族成员在肿瘤发生发展中扮演重要角色。我们发现并初步鉴定了一组调控ZEB家族基因表达的新的长非编码RNA（lncRNA），命名为ZEBAS。在预实验结果基础上，我们提出：ZEBAS可能在表观遗传水平和转录水平调控ZEB表达，而凋亡调控基因HRK等靶基因的转录又受ZEB调控；ZEBAS-ZEB-靶基因轴调控紊乱是前列腺癌发生的重要机制。ZEBAS的潜在作用机制包括①结合或募集组蛋白修饰因子及辅因子，调节组蛋白修饰（如H3K4甲基化、H3/H4乙酰化）；②竞争性结合DNA甲基转移酶及辅因子，抑制ZEB启动子甲基化；③结合或募集转录因子（如NFkB），促进ZEB转录。本课题试图明确ZEBAS-ZEB-靶基因轴调控的分子机制及其紊乱与前列腺癌生物学行为的关系。

本项目在课题组前期研究ZEB转录因子家族对下游分子的调控的基础上，发现了一组由ZEB基因启动子区反向转录产生的、具有上调ZEB转录功能的新的长非编码RNA（lncRNA ZEBAS）。课题重点研究lncRNA ZEBAS1调控ZEB1 的分子机制及其在前列腺癌中的作用。本研究发现ZEBAS1和ZEB1在前列腺癌细胞和组织中高表达；ZEBAS1促进ZEB1表达; siRNA敲减ZEBAS1明显抑制ZEB1表达，人工过表达ZEBAS1显著上调ZEB1表达水平。ZEBAS1与组蛋白甲基转移酶MLL1结合，募集MLL1至ZEB1启动子区，促进启动子区组蛋白H3K4me3修饰，增强ZEB1基因转录。ZEB1抑制miR200c基因转录，解除其对原癌基因BMI1的转录后负调控作用，促进前列腺癌细胞增殖和侵袭。ZEBAS1和ZEB1表达水平与前列腺癌高分期及神经侵犯密切相关。上述研究结果显示前列腺癌中ZEBAS1高表达，通过促进组蛋白H3K4me3修饰增加ZEB1转录，是前列腺癌细胞增殖和侵袭能力增强的重要机制，具有潜在临床应用价值。