LncRNA HIF1A-AS1在酸性微环境诱导胰腺癌血管重塑中的作用及机制

Vascular remodeling is closely correlated with tumorigenesis. Previously, we found that the acidic microenvironment promoted HIF-1α/VEGFA expression of pancreatic cancer cell. The supernatant of acidic-treated pancreatic cancer promoted sprout and tube formation of HUVEC, with inordinate arrangement of endothelial and enhanced permeability. Moreover, the lncRNA HIF1A-AS1 was also increased, while the down-regulation of HIF1A-AS1 obviously inhibited expression of HIF-1α/VEGFA. Therefore, we hypothesize that a HIF1A-AS1/HIF-1α/VEGFA axis may be involved in the angiogenesis under acidic microenvironment of pancreatic cancer. After cultured with different pH medium, the effects of HIF1A-AS1/HIF-1α/VEGFA axis on vascular remodeling were evaluated both in vitro and in vivo. FISH, RIP and RNA-pulldown experiments were applied to investigate the mechanism of HIF1A-AS1 on HIF-1α/VEGFA expression. Furthermore, the HIF1A-AS1/HIF-1α/VEGFA axis was manipulated to observe the vascular remodeling, growth and metastasis of pancreatic cancer in vivo. The present study will investigate the function of acidic microenvironment on tumorigenesis of pancreatic cancer, especially on angiogenesis. Moreover, the research will provide comprehensive data for the understanding of microenvironment on tumorigenesis and new strategy for prevention and treatment of malignant tumor.

血管重塑与肿瘤发生发展密切相关。前期发现，酸性微环境可诱导胰腺癌细胞HIF-1α/VEGFA表达上调，其培养上清增强人脐静脉内皮细胞（HUVEC）出芽及管腔形成，但内皮排列紊乱且通透性增大。此外，发现lncRNA HIF1A-AS1表达增加，抑制HIF1A-AS1可下调HIF-1α/VEGFA表达。由此推测，HIF1A-AS1/HIF-1α/VEGFA信号轴介导酸性微环境调控胰腺癌血管重塑。拟建立不同酸度胰腺癌细胞与HUVEC共培养体系及胰腺癌动物模型，观察上述信号轴对血管重塑的调控作用；通过FISH、RIP、RNA-pulldown等技术检测HIF1A-AS1对HIFα-1/VEGFA表达调控机制；在胰腺癌动物模型干预上述通路，观察胰腺癌血管重塑、生长及转移变化。本课题以血管重塑为切入点，探讨酸性微环境在胰腺癌发病中作用，为胰腺癌防治研究提供新靶点，有助于深入理解微环境对肿瘤发生中作用。

低氧微环境是肿瘤发生的关键驱动因素。因此，了解lncRNA在缺氧促进的肿瘤发生中的作用将为肿瘤提供新的诊断和治疗靶标。在本研究中，我们旨在鉴定出有助于胰腺癌（PC）进展的低氧特异性lncRNA。HIF-1α的反义lncRNA HAS1（HIF1A-AS1）在胰腺癌中显着上调，并与胰腺癌患者的不良预后相关。HAS1的敲低或过表达通过靶向HIF-1α翻译分别抑制或促进PC细胞的增殖和侵袭。机制上，HAS1通过促进AKT和YB1之间的相互作用来提高RNA结合蛋白YB1的磷酸化水平。进一步，p-YB1和HAS1的复合体被募集到HIF-1α mRNA，从而促进HIF-1α的YB1介导的翻译。相反，上调的HIF-1α作为转录因子来增强HAS1的启动子活性，形成正反馈以促进HIF-1α的过表达。总的来说，我们的研究强调了HAS1和HIF-1α的相互循环，参与低氧微环境与PC进程之间的相互作用，而HAS1可能是一种新型的预测生物标志物和治疗靶标。