miR-122反馈调节Dicer在肾透明细胞癌中的作用与机制研究

Clear cell renal cell carcinoma (ccRCC) is the most common pathological subtype of renal cell carcinoma (RCC). At present, ccRCC is lack of early diagnostic markers, and the therapeutic effect of targeted therapy is limited. Previous studies have shown that the key enzyme in the microRNA (miRNA) biogenesis process, Dicer, was downregulated in ccRCC, and the low expression of Dicer was associated with the degree of malignancy in ccRCC; however, the mechanism of Dicer downregulation is unclear. We previously performed a high throughput microarray detection of miRNA in 15 pairs of ccRCCs and adjacent tissues. Combined with bioinformatics analysis, we found that the highest up-regulated miR-122 in tumor tissues had a binding site in the 3’-UTR of Dicer, and we preliminarily verified the negative correlation between the expressions of these two in ccRCCs. This project is based on previous results and to explore the mechanism of Dicer downregulation in ccRCC from the perspective of miRNA feedback regulation of Dicer, systematically elucidate the effect of upregulating miR-122 targeting Dicer and subsequent change of downstream miRNAs on the development of ccRCC, and analyze the relationship between the expression features of miR-122/Dicer and prognosis of ccRCC patients, thus to provide a reliable theoretical basis for making Dicer regulatory pathway as a diagnostic marker and potential therapeutic target.

肾透明细胞癌（ccRCC）是肾癌最常见的病理亚型，目前缺乏早期诊断标志物，靶向治疗效果有限。前期研究表明miRNA生成过程的关键酶Dicer在ccRCC中下调，并且Dicer的低表达与ccRCC的恶性程度相关；然而其下调机制并不清楚。我们前期对15对ccRCC肿瘤及瘤旁组织进行了miRNA高通量芯片检测，结合生物信息学分析发现肿瘤组织中上调倍数最高的miR-122与Dicer 3’-UTR存在结合位点，并初步验证了二者在ccRCC中的表达呈负相关。本项目拟在前期研究的基础上从miRNA反馈调节Dicer的角度探索ccRCC中Dicer下调的机制，系统的阐明上调的miR-122靶向作用于Dicer以及下游miRNA改变对ccRCC发生发展的影响，并分析miR-122/Dicer的表达特征与ccRCC患者预后的关系，为Dicer调控通路作为相关的诊断标志物和潜在的治疗靶点提供可靠的理论依据。

尽管miRNAs的整体下调是透明细胞肾细胞癌（ccRCC）的一个普遍特征，但仍有部分miRNAs在ccRCC中是持续上调的，其中miR-122在ccRCC组织中显著升高。本研究旨在探讨miR-122在ccRCC转移中的作用及其机制。在这里，我们发现miR-122在ccRCC组织中的表达增加，并且miR-122在初诊时发生转移的ccRCC组织中的表达高于初诊时未发生转移的ccRCC组织。同时，我们发现miR-122水平升高与局限性ccRCC患者的无转移生存率降低密切相关。Dicer被证实是miR-122的直接功能靶点。miR-122的过表达促进了ccRCC细胞在体外的迁移和侵袭，促进了ccRCC细胞在体内的转移行为，而抑制miR-122可抑制这种转移表型。重要的是，miR-122通过下调Dicer及其下游miR-200家族诱导ccRCC细胞的上皮-间质转化（EMT）过程从而发挥其促转移特性。我们的结果提示miR-122/Dicer/miR-200s/EMT通路在ccRCC转移中起重要作用。此外，miR-122可能成为临床上鉴别ccRCC是否具有转移潜能的生物标志物。