胃癌外泌体中lncRNA调控血管miR-29/VEGF通路促进血管生成的新机制

In the microenvironment of tumor, cancer cells can regulate angiogenesis, and the malignant growth of blood vessels plays a key role in the proliferation and metastasis of tumors. Recent studies found that secreted exosomes from cancer cells can transport lncRNAs to work in target cells. Considering that the effect of anti-angiogenesis therapy in gastric cancer(GC) is limited, the current study is focused on the regulation of GC secreted exosomes on vascular endothelial cells. Base on clinical screening, we found a panel of exosome-lncRNAs is clearly up-regulated in gastric cancer, and one was named for its interaction with miR-29a/c, which is closely related to angiogenesis. In vitro experiments showed GC exosomes can transport lncR-angio into vascular endothelial cells,and lncR-angio adsorbs miR-29a/c and activates VEGF, thus promoting proliferation and migration of vascular endothelial cells. The current study is designed to find that GC-exosomes transport lncR-angio can regulate the process of angiogenesis by targeting the miR-29a/c-VEGF pathway both in vivo and in vitro, and explore the novel regulatory mechanism of angiogenesis in tumor microenvironment. Moreover, we will try to inhibit angiogenesis in gastric cancer by using anti-lncR-angio.The current study reveals the novel mechanism of angiogenesis and illustrates a new direction in clinical treatment.

肿瘤微环境中恶性生长的血管对肿瘤生长和转移有重要作用。外泌体是细胞分泌的微小囊泡，介导细胞间信号传递。研究发现，癌细胞可分泌外泌体携带长链非编码RNA（lncRNA）作用于其他靶细胞。鉴于胃癌抗血管治疗疗效极为有限，本课题着眼于胃癌外泌体对血管内皮细胞的调控机制。临床筛查发现胃癌外泌体中有一组lncRNAs 升高显著，其中一种lncRNA可结合与肿瘤血管生成相关的miR-29a/c，被称为lncR-angio。细胞实验表明胃癌外泌体可携带lncR-angio进入血管内皮细胞,吸附29a/c并激活其下游靶基因VEGF，促进内皮细胞增值及迁移。本课题通过运用外泌体提取、外泌体与细胞共培养、小鼠尾静脉注射外泌体技术等技术手段，证明外泌体lncR-angio与miR-29a/c 和VEGF组成的跨细胞通路参与肿瘤血管生成的新机制；并尝试运用外泌体作为运输工具靶向lncR-angio抑制肿瘤血管。

我国胃癌的发生率高，早诊率低，根治后易复发，且化疗疗效不尽人意，提示胃癌的生物学行为极为不良。肿瘤的进展和转移，不仅与癌细胞本身有关，还与肿瘤的血管生成关系密切。目前已有多种抗血管生成药物，但在胃癌中疗效欠佳。因此，寻找胃癌血管生成中新的关键信号通路，将为胃癌抗血管的靶向治疗提供新的具有应用价值的靶点和新型靶向药物。.近年来研究表明，肿瘤细胞以及正常细胞都可以分泌外泌体，包裹着RNA（miRNA，mRNA，lncRNA、CircRNA)，DNA和多种蛋白成分，作用于特定的靶器官，从而调控靶器官的信号通路。本课题着眼于血清外泌体非编码RNA在预测胃癌的潜在价值和应用，并将探讨特异性的circRNA在介导胃癌血管生成的分子机制。本研究中我们收集了胃癌患者及正常人的血清，并通过连续差速超速离心分离外泌体，用透射电子显微镜进行验证。我们首先用TaqMan LowDensity Array从血清外泌体中筛选差异表达的血清非编码RNA，使用RT-qPCR对其进行验证，发现一组在胃癌患者血清中稳定差异表达的 circRNAs。进一步我们用体外实验证明，胃癌细胞系中circ_0044366（circ-29）以外泌体的形式由肿瘤细胞分泌，这些胃癌细胞分泌的circ-29被递送到受体血管内皮细胞中，通过靶向miR-29/VEGF来促进内皮细胞中VEGF基因的表达，促进肿瘤血管增殖及成环。此外，通过体内研究表明，癌细胞分泌的circ-29介导肿瘤血管生成及肿瘤生长。我们的结果表明，胃癌来源的外泌体circ-29通过靶向miR-29a/c-VEGF促进血管生成，从而促进肿瘤进展。本课题为预测胃癌提供了潜在的血清circRNA标志物，并阐明了circ-29在肿瘤血管生成中的分子机制，具有重要的临床意义。