肿瘤相关成纤维细胞经外泌体介导的环状RNA ciRS-7调控胰腺癌细胞自噬促进Warburg效应的机制研究

Pancreatic cancer is characterized by enhanced autophagy and high glycolysis activity, yet the underlying mechanisms remain unclear. Based on our previous researches, we hypothesize that exosome-transmitted circular RNA ciRS-7 derived from CAFs in pancreatic cancer microenvironment modulates the autophagy of cancer cells to support Warburg effect. This proposal focuses on the interaction of CAFs with cancer cells in pancreatic cancer microenvironment, and investigates that exosomes act as a messenger to regulate autophagy to increase the supply of intracellular glucose to glycolysis and ultimately promote tumor progression. The researches would be conducted from the multiple levels upon cancer cells, tumor-burdened animal models and clinical tissues by using comprehensive research technologies in cancer biology. We would first explore the effects of exosomes derived from CAFs on the autophagy and glycolysis metabolism of pancreatic cancer, and then investigate the underlying molecular mechanisms by which exosome-transmitted ciRS-7 derived from CAFs enhances autophagy activity to up-regulate glycolysis through ciRS-7/miR-7 axis. Last, we would probe into the feasibility of down-regulation of exosome-transmitted ciRS-7 for impeding pancreatic cancer progression and assess the correlation between the expression levels of ciRS-7 and the clinical outcomes. This research will contribute to insight into the underlying molecular mechanisms of pancreatic cancer progression in view of tumor microenvironment, and also provide a new look at pancreatic cancer therapy and prognosis.

胰腺癌具乏氧高代谢及依赖自噬生长的特征，但其内在作用机制仍不清楚。基于前期研究工作，我们提出在胰腺癌微环境中肿瘤成纤维细胞(CAF)经外泌体介导环状RNA ciRS-7调控肿瘤细胞自噬而促进Warburg效应。课题着眼于胰腺癌微环境中CAF对肿瘤细胞的影响，探讨外泌体作为信使调控肿瘤细胞自噬过程，影响对糖酵解的糖源供应，继而促进肿瘤进程。课题拟综合运用现代肿瘤生物学研究技术，从肿瘤细胞、模型动物、临床样本等多层面进行探讨。课题首先分析CAF释放的外泌体对胰腺癌细胞自噬、糖酵解及增殖的影响，继而阐释CAF经外泌体介导的ciRS-7通过ciRS-7/miR-7轴促进自噬上调糖酵解水平的详细分子机制，最后探索干预外泌体ciRS-7分泌抑制胰腺癌进展的可行性，分析ciRS-7表达水平与患者预后之间的关系。课题有助于理解肿瘤微环境视野下胰腺癌进展的分子机制，也为胰腺癌治疗与预后判断提供了新思路。

胰腺癌具有乏氧、高代谢、且依赖自噬生长等显著特征，但其内在作用机制仍不清楚。环状RNA具有阻碍miRNA对靶mRNA的抑制或降解作用，从而调节靶基因mRNA及其蛋白的表达。近年研究发现，ciRS-7在胃肠道肿瘤中发挥促癌作用，但其在胰腺癌中的生物学作用及其具体的分子机理尚未明了。基于前期研究工作，我们提出在胰腺癌微环境中肿瘤成纤维细胞（CAF）经外泌体介导环状RNA ciRS-7调控肿瘤细胞自噬而促进Warburg效应。基于此，课题首先分析胰腺癌肿瘤相关成纤维细胞释放的外泌体对胰腺癌细胞自噬、糖酵解代谢及增殖的影响，检测外泌体环状RNA-7的表达；继而阐释CAF经外泌体介导的ciRS-7通过ciRS-7/miR-7轴促进自噬上调糖酵解水平的详细分子机制，最后干预ciRS-7/miR-7轴抑制胰腺癌进展的可行性，分析miR-7表达水平与患者预后之间的关系。结果发现，在胰腺癌CAF分泌的外泌体中ciRS-7呈高表达状态，具有促进胰腺癌细胞糖酵解和增殖的作用。ciRS-7通过抑制miR-7调控LKB1-AMPK-mTOR信号通路、自噬诱导及延长过程中的ULK2、ATG4A、ATG7基因，进而促进自噬，从而影响对糖酵解的葡萄糖供应，最终促进肿瘤的增长、迁移与转移。重要的是，ciRS-7作为miR-7的海绵体，重组慢病毒介导的miR-7可以通过干预自噬影响糖酵解代谢，有效抑制胰腺癌PDX模型肿瘤的生长。此外，研究还发现，低表达水平miR-7不仅与患者预后差相关，而且miR-7与胰腺癌分期也有关。. 总之，胰腺癌CAF外泌体ciRS-7海绵吸附miR-7，而ciRS-7/miR-7轴通过调控自噬过程为糖酵解提供葡萄糖“储存库”，从而促进胰腺癌的进展。研究阐明了ciRS-7/miR-7轴在胰腺癌细胞中的精细调控分子机制，明确了miR-7在胰腺癌发生、发展与转移过程中的抑制作用。我们的研究结果提示：ciRS-7可作为miR-7的海绵子体，而miR-7可作为一种新的生物标记物判断胰腺癌的预后，同时过表达miR-7可靶向自噬过程来干预胰腺癌进程。