miR-21靶基因3’-UTR遗传变异与结直肠癌发病风险及其机制研究

Colorectal cancer (CRC) is one of the common malignancies, which is jeopardizing human health. Many research revealed that circulating miRNA stable in blood was considered to be a novel biomarker for noninvasive diagnosis of cancers. It was possible that genetic variants in 3’-untranslated region of target genes could make a contribution to the gene pro-transcription regulation by altering the binding capacity to miRNA, which was closely related to tumor development and progression. In the preliminary studies, a comprehensive Meta-analysis and an independent validation in CRC plasma and tissues were performed, and we verified that miR-21 was a promising biomarker in diagnosis of CRC. However, biological mechanisms were not clear currently. In this study, we screened the SNPs in the 3’-UTR of miR-21 target genes. By using Molecular epidemiology method and a series of molecular biology techniques, we, preliminary revealed that the molecular mechanism of gene pro-transcription regulation of the SNPs in the 3’-UTR and the potential biological mechanisms of tumor cell multiplication, apoptosis, invasion and metastasis involved in the development and progression of CRC. These results provide important references for early detection and treatment of CRC.

结直肠癌是危害人类健康最常见的恶性肿瘤之一。大量研究表明，在外周血中稳定存在的血浆微小RNA（miRNA）可作为新的无创伤性肿瘤生物标志物。其中可能的机制是miRNA可以通过其靶基因3’-UTR结合区域的遗传变异改变其与miRNA的结合，影响转录后翻译以实现对基因的调控，从而与肿瘤的发生有关。本课题组前期通过Meta分析和实验验证发现在结直肠癌中稳定存在的血浆miR-21为最具有结直肠癌诊断价值的miRNA，然而目前其作用机制尚不清楚。本项目拟在前期研究的基础上，筛选miR-21靶基因3’-UTR结合的SNPs，采用分子流行病学研究方法和一系列细胞分子生物技术，初步揭示miR-21靶位点SNPs调控下游靶基因转录后翻译的分子机制，从而阐明miR-21影响肿瘤细胞增殖、凋亡、侵袭转移的可能生物学机制，为今后结直肠癌的早期预防、干预和个体化治疗提供重要参考。

结直肠癌是全球最常见的恶性肿瘤之一，其发病率排名第三，死亡率排名第四。遗传因素在结直肠癌的发生发展中起到重要作用。在microRNAs结合区域的单核苷酸多态性（SNPs）可能会改变miRNAs与靶基因的3’-UTR区的结合能力，从而影响肿瘤的易感性。MiR-21已经被报导参与结直肠癌的发生发展。然而，其结合区域的SNPs与结直肠癌的关系仍未被阐明。.我们共纳入了1147例结直肠癌病例和1203个健康对照，通过病例对照研究评估了miR-21结合区域SNPs与结直肠癌发病风险的关系。结果发现，在相加模型中，rs6504593位点C等位基因的个体患结直肠癌的风险显著增加（调整OR = 1.19, 95% CI = 1.04-1.36, P = 0.011）。生物信息学预测及双荧光素酶报告基因实验证实，rs6504593位点的T等位基因可以通过改变miR-21与IGF2BP1的3’-UTR区的结合能力负向调控IGF2BP1 mRNA的表达水平。另外，外源性的miR-21可以影响细胞的凋亡和增殖。.综上所述，rs6504593 T>C遗传变异能够显著增加结直肠癌的发生风险，且该位点可通过减少miR-21与靶基因3’-UTR的结合能力来上调IGF2BP1的表达。另外，我们也进一步验证了miR-21通过参与调控结直肠癌细胞增殖、凋亡等能力，发挥促癌样作用。因此，我们认为IGF2BP1 rs6504593可能与结直肠癌的易感性相关，而且它可以作为一个预测结直肠癌发病风险的潜在生物学标志物。