目的：探讨放化疗抵抗的结直肠癌细胞发生上皮–间质转化(epithelial-mesenchymal transition，EMT)的意义。方法：采用5-FU化疗同期进行放疗对人结直肠癌野生型细胞(HCT116)进行干预，诱导放化疗共同抵抗的细胞株(HCT116CRR)并采用克隆形成实验进行放化疗抵抗性的鉴定。高倍显微镜下观察细胞形态学变化。采用Real-time PCR和Western印迹，检测上皮表型标志物E-cadherin，间质表型标志物N-cadherin、波形蛋白(vimentin)、核转录因子(Snail)mRNA及其蛋白的表达。结果：放化疗抵抗的结直肠癌细胞发生与EMT相符的形态学改变，细胞呈纺锤体状，极性消失，并出现伪足；Real-time PCR和Western印迹结果显示E-cadherin mRNA及蛋白表达下调；N-cadherin，vimentin，Snail mRNA及蛋白表达上调，差异有统计学意义(P<0.05)。结论：放化疗抵抗后的人结直肠癌细胞发生EMT，其与结直肠癌的治疗抵抗相关。
Chemoradiotherapy can induce epithelial-mesenchymal transition of the human colorectal cancer cells
Objective: To investigate the significance of epithelial-mesenchymal transition (EMT) of human colorectal cancer cells with resistance to chemoradiotherapy. Methods: Colorectal cancer cells were exposed to 5-fluorouracil (5-FU) while radiotherapy was given at the same time. A small number of cells that survived from chemoradiotherapy were obtained, and their morphological changes were observed by microscopy. Our group then identified the resistance using colony formation assay. Real-time PCR and Western blot were used to detect the mRNA and its protein expression of epithelial marker E-cadherin, mesenchymal marker N-cadherin, vimentin, and nuclear transcription factor snail. Results: Colorectal cancer cells which were resistant to chemoradiotherapy showed phenotypic changes consistent with EMT: spindle-cell shape, loss of polarity, and pseudopodia formation. Real-time PCR and Western blot results: E-cadherin mRNA and protein expression level were lower, and N-cadherin, Snail, vimentin mRNAs and proteins expression level were higher, the difference was statistically significant (P<0.05). Conclusion: Colorectal cancer cells resistance to chemoradiotherapy can induce epithelial-mesenchymal transition (EMT), and EMT may be related to resistance of chemoradiotherapy of colorectal cancer.