DEVELOPMENT OF A NEW MOLECULAR TARGETING THERAPY FOR ESOPHAGEAL CANCER USING CYCLIN DEPENDENT KINASE (CDK) INHIBITOR

目的：黄匹吡醇是一种人工合成的黄酮，对多种癌症具有抗肿瘤作用。本实验研究了黄匹利多单用及低剂量黄匹利多联合放疗对食管鳞状细胞癌细胞系的体外影响。实验设计：将食管鳞状细胞癌TE8、TE9、KE4细胞株（0.05 ~ 400 nM）暴露于黄吡醇48 h， MTT法评价细胞毒性，流式细胞术检测细胞周期分布，Western blotting检测细胞周期蛋白Dl、Bcl-2、Rb蛋白表达。采用致克隆法测定0.05 nM黄匹吡醇联合放疗的效果。结果：IC_<50>约为110 ~ 250 nM。0.05 nM黄酮吡醇处理48 h， G_2 /M群体增加，300 nM黄酮吡醇处理48 h， G_1群体增加。在300 nM浓度下，三种细胞系均出现核碎裂和染色质凝聚现象。300 nM黄吡醇可降低3种细胞系细胞周期蛋白Dl和Rb蛋白水平，TE8和KE4细胞中bcl-2蛋白水平也降低。此外，暴露于0.05 nM黄吡醇可轻微降低KE4细胞中cyclin D1、Rb和Bcl-2蛋白的水平。0.05 nM黄吡醇与辐射对三种细胞系均有显著的协同效应。结论：低剂量黄吡醇联合放疗治疗食管鳞状细胞癌具有协同作用。低剂量黄吡醇可能是提高食管癌放疗疗效的一种有效的新治疗方法。

Purpose: Flavopiridol is a synthetic flavone that has shown an antitumor effect against several cancers. Here, we investigated the in vitro effect of flavopiridol alone and the combined effect of low-dose flavopiridol plus radiation on esophageal squamous cell carcinoma cell lines. Experimental design: Esophageal squamous cell carcinoma cell lines (TE8, TE9, and KE4) were exposed to flavopiridol (0.05-400 nM) for 48 h. Cytotoxicity was evaluated by the MTT assay, cell cycle distribution was determined by flow cytometry, and cyclin Dl, Bcl-2, and Rb protein expression was detected by Western blotting. The effect of 0.05 nM flavopiridol combined with radiation was determined by the clonogenic assay. Results: The IC_<50> was approximately 110-250 nM. Exposure to 0.05 nM flavopiridol for 48 h increased the G_2 /M population, while 300 nM increased the G_1 population. At a concentration of 300 nM, nuclear fragmentation and chromatin condensation were observed in all three cell lines. Exposure to 300 nM flavopiridol decreased the levels of cyclin Dl and Rb protein in all three cell lines and bcl-2 protein was also decreased in TE8 and KE4 cells. Moreover, exposure to 0.05 nM flavopiridol slightly decreased the levels of cyclin D1, Rb, and Bcl-2 protein in KE4 cells. A significant synergistic effect of 0.05 nM flavopiridol and radiation was observed for all three cell lines. Conclusion: Combined treatment with low-dose flavopiridol and radiation showed a synergistic effect on esophageal squamous cell carcinoma. Administration of a low dose of flavopiridol could be a potent new therapeutic approach for improving the efficacy of radiotherapy against esophageal cancer.