Hif-2a/miR-5787通过抑制坏死性凋亡在结肠癌5-Fu化疗耐药中的作用和机制研究

5-Fu (5-fluorouracil) is the base agent of chemotherapy for colon cancer, but 5-Fu chemoresistance becomes the greatest difficulty in the therapeutic workup. In our previous study, colon cancer cells developed chemoresistance to 5-Fu in chronic hypoxia, while interfering Hif-2α would enhance the chemosensitivity of 5-Fu. Hif-2α could upregulate the expression of miR-5787 and block the expression of RIP1, a crucial molecule in the process of necroptosis. Besides, miR-5787 also inhibited the expression of RIP1. However, the effect and molecular mechanisms of Hif-2α/miR-5787 on necroptosis and 5-Fu chemosensitivity in colon cancer have been clarified yet. This project would explore the transcriptional regulatory sites of miR-5787 by Hif-2α and RIP1 by miR-5787. What’s more, the effects of these molecules on 5-Fu chemosensitivity would be measured in colon cancer cells, nude mice xenograft tumor and human colon cancer specimens. These researches will confirm the regulatory mechanism of Hif-2α/miR-5787/RIP1 pathway in colon cancer, and lay an experimental foundation to resolve the dilemma of 5-Fu chemoresistance in colon cancer, showing important theoretical significance and potential application value.

5-氟尿嘧啶（5-Fu）是结肠癌化疗的基础药物，然而5-Fu耐药成为治疗的最大难题。我们前期研究发现，慢性低氧下结肠癌细胞对5-Fu化疗耐药，干扰Hif-2α可以增加5-Fu化疗的敏感性；Hif-2α可以增强miR-5787的表达、抑制细胞坏死性凋亡关键分子RIP1的表达，miR-5787亦可以抑制RIP1的表达。但结肠癌中Hif-2α依赖miR-5787对坏死性凋亡和5-Fu化疗敏感性的影响及分子机制尚未阐明。本项目拟研究Hif-2α对miR-5787及miR-5787对RIP1转录调控的位点，并在细胞模型、裸鼠移植瘤及人结肠癌标本中检测这3个分子对5-Fu化疗敏感性的影响。通过这些研究，将发现结肠癌中Hif-2α/miR-5787/RIP1通路的调控机制及在5-Fu化疗敏感性中的作用，为解决结肠癌5-Fu化疗耐药的难题奠定实验基础，具有重要的理论意义和潜在应用价值。

5-氟尿嘧啶（5-Fu）是结肠癌化疗的基础药物，然而5-Fu耐药成为治疗的最大难题。本课题主要进行了以下研究：结肠癌细胞中Hif-2α对miR-5787以及miR-5787对RIP1转录活性的调节；结肠癌细胞中Hif-2α通过miR-5787对坏死性凋亡和5-Fu化疗敏感性的影响；裸鼠移植瘤模型中Hif-2α对miR-5787和RIP1的表达及5-Fu化疗敏感性的影响；人结肠癌标本中Hif-2α、miR-5787和RIP1的表达及同患者预后的相关性。研究在结肠癌细胞中发现Hif-2α同HRE-WL2结合，Hif-2α通过HRE-WL2调控miR-5787的转录活性，miR-5787通过RRW1 调控RIP1的转录活性。Hif-2α敲低后，坏死性凋亡细胞明显增加，miR-5787 mimics则明显减少坏死性凋亡细胞的比例。miR-5787 通过RIP1调控结肠癌细胞的5-Fu化疗敏感性，Hif-2α通过miR-5787和坏死性凋亡分子RIP1影响5-Fu化疗敏感性，裸鼠移植瘤模型中Hif-2α减弱5-Fu化疗的敏感性，Hif-2α过表达组瘤块中miR-5787的mRNA表达明显增加，RIP1的mRNA表达则明显减少。人结肠癌标本中Hif-2α、miR-5787的表达明显高于癌旁组织，RIP1的表达则明显低于癌旁组织。结肠癌标本中Hif-2α、miR-5787和RIP1的表达同预后相关。通过这些研究，发现了结肠癌中Hif-2α/miR-5787/RIP1通路的调控机制及在5-Fu化疗敏感性中的作用，对于解决结肠癌5-Fu化疗耐药问题具有潜在临床应用价值。