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

目的：黄烷醇是一种人工合成的黄酮类化合物，已显示出抗多种癌症的作用。在此，我们研究了黄烷醇单独作用以及低剂量黄烷醇联合放射治疗对食管鳞癌细胞株的体外作用。实验设计：将人食管鳞癌细胞株(TE8、TE9、KE4)分别置于0.05~400 nM的黄烷醇作用48h后，用四甲基偶氮唑盐比色法检测细胞毒作用，流式细胞仪检测细胞周期分布，Western blotting检测细胞周期蛋白Dl、Bcl2、Rb蛋白的表达。用克隆形成法检测0.05 nM黄烷醇联合放射治疗的效果。结果：IC50约为110~250 nm。0.05 nM黄烷醇作用48 h后，G2/M期细胞数增加，300 nM组细胞G1期细胞数增加。在300 nM浓度下，三种细胞系均可见核碎裂和染色质凝集。300 nM黄烷醇可使三种细胞株的细胞周期蛋白Dl和Rb蛋白表达水平降低，bcl2蛋白在TE8和KE4细胞中的表达也降低。此外，0.05 nM黄烷醇作用于KE4细胞后，细胞周期蛋白D1、Rb和Bcl2蛋白表达水平略有下降。0.05 nM的黄烷醇与辐射对三种细胞株均有明显的协同作用。结论：小剂量黄烷醇联合放射治疗对食管鳞癌有协同作用。小剂量黄烷醇可能是提高食道癌放射治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.