端粒酶抑制剂-imetelstat对食管鳞癌放射增敏及机制的实验研究

China is the contry having highest incidence and mortality rate for esophageal cancer. Radiation therapy is one of most important ways to treat esophageal cancer, but with poor patient outcomes. So looking for the low toxicity and efficient sensitizer to enhance the effect of radiation therapy is current hot topic. Our previous study on esophageal squamous cancer cells showed that telomerase inhibitor-imetelstat can significantly inhibit telomerase activity and growth of esophageal squamous cancer cells and lead to increased number of DNA double strand breaks induced by high-energy X-ray resulting more DNA damages. These previous results indicated that imetelstat can enhance the killing effect of radiation for esophageal squamous cancer. This project intends to: 1. treat esophageal squamous cancer cells with imetelstat and X-ray in vitro and in vivo, then employ clonogenic survival assay and solid tumor growth assay to study radiosensitization effect of imetelstat; 2. To understand the mechanism how imetelstat radiosensitize esophageal cancer, we employ pulse field gel electrophoresis to detect small DNA fragments after radiation in esophageal squamous cancer cells and employ western blot to investigate the expression and phosphorylation of key proteins in DNA repair system. Illustrate the above mechanism will provide experimental evidence for clinical application of imetelstat for treatment of esophageal squamous cancer together with radiation.

中国是食管癌发病率和死亡率最高的国家，放射治疗是食管癌治疗的重要手段，寻找低毒高效的增敏剂以提高放射治疗效果是当前研究的热点。我们前期用食管鳞癌细胞研究显示：端粒酶抑制剂-imetelstat能抑制食管鳞癌细胞中的端粒酶活性以及细胞的生长，并能增加高能X线照射引起的DNA双链断裂的数量导致更多的DNA损伤，推测该抑制剂能增强放射对食管癌的杀伤作用。本课题拟：1.采用高能X线对体外培养细胞、体内实体瘤进行照射，通过细胞克隆形成、实体瘤生长等检测，探讨imetelstat对食管鳞癌的放射增敏作用；2.通过脉冲场凝胶电泳检测照射后食管癌细胞中DNA断裂片段，用western blot检测DNA损伤修复系统中关键蛋白因子表达和磷酸化水平以及一些列其它实验，探讨imetelstat放射增敏的分子机制。阐明上述机制将为imetelstat联合放射治疗食管鳞癌临床应用提供实验依据。

放射治疗是食管癌治疗的重要手段，寻找低毒高效的增敏剂以提高放射治疗效果是当前研究的热点。我们前期用食管鳞癌细胞研究显示：端粒酶抑制剂—imetelstat能抑制食管鳞癌细胞中的端粒酶活性以及细胞的生长，并能增加高能X线照射引起的DNA双链断裂的数量导致更多的DNA损伤，推测该抑制剂能增强放射对食管癌的杀伤作用。本课题通过体外细胞实验和动物实验研究了端粒酶抑制剂imetelstat对食管鳞癌放射增敏作用。并通过对DNA双链断裂修复信号通路中关键蛋白、细胞周期以及细胞凋亡等研究进一步了解该抑制剂放射增敏的机理。通过细胞实验和动物实验证明端粒酶抑制剂imetelstat主要通过增加凋亡和抑制细胞增殖来增加放射对肿瘤细胞的杀伤作用，为端粒酶抑制剂imetelstat作为放射增敏剂联合放射治疗食管癌提供实验依据。