外泌体miR-21对结直肠癌间质血管生成及通透性的作用与调控机制

The molecular of cancer-secreted exosomes such as miRNAs can reshape tumor microenvironment. MiR-21 has been reported to be up-regulated in exosomes of colorectal cancer (CRC) patients. However, the role and potential mechanism of exosomal miR-21 in CRC remains elucidated. Our previous studies have revealed that miR-21 correlated significantly with CRC stromal vascular. Further experiments have shown that exosomes, low-expressing miR-21 and derived from miR-21 silencing CRC cells, suppressed endothelial cells proliferation, migration and angiogenesis. Based on the bioinformatic analyses and previous experiments, we proposed a hypothesis that exosomal miR-21，secreted by CRC cells, could regulate angiogenesis and vascular permeability in CRC by suppressing target gene KRIT1 and Rap1 signaling pathway. In order to validate the hypothesis, endothelial permeability, chick embryo chorioallantoic membrane assay, orthotopic mouse metastasis models and so on will be performed to verify roles of exosomal miR-21 in angiogenesis and vascular permeability. Then we will analyze that target gene KRIT1 and Rap1 signaling pathway can be modulated by exosomal miR-21, using Bioinformatics methods, WesternBlot, etc. At last, we will measure the expression of miR-21 and KRIT1 in matched CRC tissues and analyze the clinicopathologic significance separately. The project may provide a potential therapeutic target for angiogenesis and vascular permeability of CRC.

肿瘤细胞外泌体中的活性物质如miRNA能重塑肿瘤微环境，已报道结直肠癌患者外泌体中miR-21表达上调，但其在结直肠癌的作用机制不清楚。预实验结果表明miR-21与结直肠癌间质血管密切相关；结直肠癌细胞干扰miR-21后，其miR-21低丰度的外泌体抑制内皮细胞增殖、迁移及血管生成。结合前期实验结果及生物信息学分析，我们提出假设：结直肠癌细胞外泌体中的miR-21通过抑制靶基因KRIT1及Rap1信号通路调控癌间质血管生成及通透性的可能机制。为探讨该机制，拟用血管通透性试验、鸡胚血管生成试验、盲肠原位接种试验等方法研究外泌体miR-21对血管生成及血管通透性的影响；采用生物信息学、WB等分析内皮细胞中miR-21调控靶基因KRIT1及Rap1信号通路的可能机制；在组织样本中探讨miR-21与KRIT1在结直肠癌间质血管中的表达及临床意义。本项目将为结直肠癌血管治疗靶点的筛选提供科学依据。

癌细胞分泌的外泌体是癌症-宿主之间信息传递的重要介质。本研究中，我们发现结直肠癌细胞分泌的外泌体能将miR-21-5p传递到内皮细胞中，上调内皮细胞中miR-21-5p的表达。在内皮细胞中，miR-21-5p抑制靶基因KRIT1的表达，随后激活β-catenin信号通路，上调下游血管相关靶点VEGFa和Ccnd1的表达水平，最终促进血管生成及血管通透性。在结直肠癌间质血管中，miR-21-5p与KRIT1的表达水平呈显著负相关。此外，结直肠癌患者的血浆外泌体中miR-21-5p的表达水平显著高于健康人。因此，我们的数据表明外泌体miR-21-5p参与调控结直肠癌间质的血管生成及血管通透性，能够成为一个潜在的治疗靶点。