MiR-21促进食管癌放射抗拒相关机制研究

There are 53% of patients with esophageal cancer of the world in our country, with a high incidence, refractory and poor efficacy characteristics. Radiotherapy is one of the main treatment for esophageal cancer. Hypoxia inducible factor 1α (HIF-1α) expression is closely related with radiation resistance in esophageal cancer cells, HIF-1 inhibitory factor (FIH-1) can be reduced by hypoxic conditions in the solution HIF-1α. Our previous studies have shown: the plasma levels of miR-21 in the patients with esophageal cancer accepted concurrent chemoradiotherapy is closely related to the effectiveness of radiotheraoy, cell experiments also found that miR-21 might be involved in the regulation FIH-1/HIF-1α. To this end, we propose the hypothesis: miR-21 may inhibit esophageal hypoxic cells FIH-1/HIF-1α degradation pathway, mediated resistance to radiotherapy of esophageal cancer. To test this hypothesis, we tried from the molecular, cellular and animal levels to explore, such as miR-21 expression in esophageal radiation resistance of the role of miR-21 and clear pathways play a role by regulating mechanism FIH-1/HIF-1α . In this study, miR-21 regulation from the viewpoint FIH-1/HIF-1α reveal new mechanisms of resistance to hypoxia radiotherapy, radiotherapy resistance to reverse provide new ideas.

我国食管癌患者占世界的53%，具有高发、难治、疗效差的特点。放疗是食管癌的主要治疗手段之一。食管癌细胞乏氧诱导因子-1α(HIF-1α)表达与放射抗拒密切相关，HIF-1抑制因子-1(FIH-1)可在乏氧条件下降解HIF-1α。我们的前期研究显示：接受同步放化疗的食管癌患者血浆miR-21表达水平和放疗疗效密切相关，细胞实验也发现miR-21可能参与调控FIH-1/HIF-1α通路。为此，我们提出假说：miR-21可能通过抑制食管癌乏氧细胞FIH-1/HIF-1α降解途径，促进食管癌的放射抗拒。为验证这一假说，我们试图从分子、细胞及动物水平等来探讨miR-21表达在食管癌放射抗拒中的作用，并明确miR-21通过调控FIH-1/HIF-1α途径发挥作用的机制。本研究将从miR-21调控FIH-1/HIF-1α通路的新视点揭示食管癌乏氧后放射抗拒的机制，为逆转肿瘤放射抗拒提供新思路。

食管癌是世界范围内常见致死性癌症类型之一，特别是在中国的一些地区。食管鳞状细胞癌（ESCC）是食管癌的主要亚型，其发生与不健康的饮食习惯，吸烟，环境致癌物等有关。OSCC通常进展缓慢，但一经确诊时多为晚期。因此阐明ESCC发生发展的分子机制势在必行。MicroRNA是一类18~24bp的小非编码RNA，在细胞生长、发育和衰老等生命过程中扮演着重要角色调节。miR-21是人类组织和细胞中较早发现、广泛存在的microRNA之一，是实体肿瘤中最常见的过高表达microRNA。课题组通过文献综述发现，miR-21与多种肿瘤细胞放射敏感性密切相关，可通过改变凋亡，促进自噬等途径影响放射敏感性。临床前研究证明在食管癌细胞株中，miR-21过表达具有辐射抗性，而敲除miR-21具有辐射增敏性。此外，miR-21与类胰岛素生长因子结合蛋白3（IGFBP3）作用有能是ESCC细胞辐射抵抗的原因。基于上述应用，我们通过采用microRNA敲除、克隆形成、细胞凋亡、Western blot、免疫组化等实验手段，在分子水平和细胞水平来探讨miR-21对食管鳞状细胞癌生长和辐射敏感性的影响及其可能的机制。结果如下：敲低miR-21可下调HIF-1α、IGFBP3蛋白的表达，增加乏氧食管癌细胞的凋亡，并发挥对乏氧情况下ECA109细胞的放射增敏作用，且此增敏效应在体内实验中得到证实。我们认为：miR-21可称为一种新的预测ESCC癌症预后的生物标记候选，并作为一种新的放射增敏靶点，是构成食管癌生物学复杂度的有前途的新组分。