miR-31在结直肠癌肿瘤血管生成中的作用及机制研究

Uncovered from the forgotten landscape of ‘dark genomic matter’, microRNAs have become rising stars in cancer genetics. MicroRNAs are endogenous non-coding, single-stranded RNAs of ~22 nucleotides which function as post-transcriptional gene regulators. The aberrant expression of miR-31 has been found in various cancers, and takes part in the development, progression and treatment response of cancer. But there is no report regarding the miR-31 in tumor angiogenesis. Our previous studies reveal that miR-31 is up-regulated in colorectal cancer (CRC), and has positive relationship with TNM stage and local invasion. Suppression of miR-31 increases the sensitivity to 5-FU at an early stage and affect cell migration and invasion in HCT-116 colon cancer cells. Moreover, recent investigation has indicated that miR-31 is one of the signature microRNAs of blood vascular endothelial cells. To address the role of miR-31 in tumor angiogenesis in CRC, we would detect the expression pattern of miR-31 in CRC through in situ hybridization, and analyze its relationship with microvessel density (MVD). MiR-31 sponge would be generated and transfected into HCT-116 to get stable miR-31 knock-down colon cancer cell line. The role and potential mechanism of suppression of miR-31 in tumor angiogenesis would be studied through chick chorioallantoic membrane assay (CAM) and mice model in vivo. Our results would give important clues regarding the miR-31-based anti-angiogenic therapy in CRC.

miR-31在多种肿瘤中异常表达，参与了肿瘤的发生发展过程。然而，目前尚无miR-31和肿瘤血管生成的研究报道。前期研究中我们发现，结直肠癌（CRC）中miR-31表达升高且和TNM分期及肿瘤局部浸润正相关；抑制miR-31，可增加结肠癌细胞HCT-116对5-FU的敏感性，并影响细胞的侵袭和迁移能力。新近的文献表明，miR-31可作为血管内皮细胞的标志性microRNA。我们推测miR-31和CRC肿瘤血管生成相关。为验证这一假设，我们拟采用原位杂交技术，研究miR-31在CRC中的定位及分布特点，探讨其和肿瘤血管生成之间的关系。构建miR-31 sponge并转染HCT-116细胞，获得稳定敲减miR-31的细胞系，通过裸鼠移植瘤模型及鸡胚尿囊膜血管生成实验，研究miR-31对结肠癌肿瘤血管生成的影响及作用机制，分析评价CRC中以miR-31为靶点的抗血管治疗的可行性。

本课题研究了结直肠癌中miR-31和肿瘤血管生成之间的关系。结直肠癌中miR-31 表达升高且和TNM 分期及肿瘤局部浸润正相关。抑制miR-31可降低结肠癌细胞HCT-116 的迁移能力。miR-31主要定位于肿瘤细胞胞浆中，部分间质的炎症细胞也呈阳性表达。miR-31高表达的肿瘤中，微血管密度增加，表明结直肠癌中miR-31和肿瘤血管生成相关。构建miR-31 sponge 并转染HCT-116 细胞，获得稳定敲减miR-31 的细胞系。进一步分析发现，miR-31可能通过血管相关因子PAI-1、TIMP-1、Angiogenin、PDGF和VEGF来调节结直肠癌中肿瘤血管的生成，这为结直肠癌中以miR-31 为靶点的抗肿瘤血管治疗提供了实验依据。