SIRT1调控miRNAs的加工成熟参与胃癌侵袭转移的机制研究

Invasion and metastasis are the major obstacle of gastric cancer therapy and related closely with poor prognosis. miRNAs are considered to be the key post-transcriptional regulator in tumor metastasis. But the mechanisms involved in regulating miRNAs processing and their functions especially on malignant phenotypes of tumor are largely unknown. Our previous study showed that deacetylase SIRT1 was highly expressed in gastric cells with higher metastatic potential. miRNAs array analysis showed that elimination of SIRT1 mediated multiple metastasis related miRNAs disturbance which couldn't be explained by specifically regulation of miRNA transcription. Co-IP assay found possible interaction between SIRT1 and miRNA processor component Drosha. These findings implied that SIRT1 may regulate the processing and maturation of miRNAs. It has been newly reported that tumor suppressor p53，one of the substrate of SIRT1，might play a key role in regulating miRNAs processing. So we wonder if the deacetylation of p53 was involved in the regulation of miRNA processing by SIRT1. This study aims to investigate the molecular mechanisms involved in SIRT1 modulation of miRNA processing and maturation，especially on protein interaction and epigenetics modification, and their possible function in gastric cancer metastasis. This novel mechanism of gastric cancer metastasis and miRNA processing regulation may provide new strategies for gastric cancer treatment.

miRNA在胃癌转移中发挥重要的转录后调控功能，目前研究多集中在miRNA对靶分子的调节机制，关于调控miRNA加工成熟在肿瘤中的作用和机制还远未阐明。课题组前期研究发现组蛋白去乙酰化酶SIRT1在转移潜能高的胃癌细胞系表达显著升高；芯片筛选发现抑制SIRT1表达引起大量转移相关miRNA分子的表达变化，无法用SIRT1对某个或某几个miRNA的特异性调控解释；Co-IP显示SIRT1与miRNA加工复合物成员Drosha可能存在相互作用，强烈提示SIRT1可能调控miRNA加工成熟。新近报道了SIRT1底物p53调控miRNA加工成熟的新功能，那么SIRT1对p53的去乙酰化是否涉及其中？我们拟从蛋白质相互作用和表观遗传学调控等多个角度，探索SIRT1对miRNA加工成熟的分子调控机制及其在胃癌侵袭转移中的作用。本课题将有望发现miRNA的非转录调控参与胃癌转移的新分子机制。

MiRNA在胃癌多项恶性生物学表型中发挥重要的转录后调控功能。课题组前期研究发现SIRT1在胃癌细胞系表达显著升高；芯片筛选发现抑制胃癌细胞中SIRT1的表达引起了大量同源miRNA分子的表达变化。本课题中，我们深入研究了SIRT1在胃癌细胞增殖、凋亡等多种恶性生物学表型中的作用及分子机制。验证和研究了SIRT1对miRNAs非特异调控作用，运用质谱技术在胃癌细胞中筛选获得了一批与SIRT1直接相互作用的分子群，生物信息学分析提示其可能直接参与了RNA加工与成熟。在此基础上研究探讨了SIRT1-ADAR1信号通路在胃癌细胞中对多个miRNA分子的调控作用。. 总体上本课题完成了预定的研究目标，明确了SIRT1显著促进胃癌细胞增殖，抑制胃癌细胞凋亡的信号通路，揭示了SIRT1-ADAR1信号通路在胃癌细胞中对多个miRNA分子的调控作用。上述结果和发现部分阐明了SIRT1参与胃癌细胞多个恶性生物学表型及RNA加工的新分子机制。