目的:探讨X线照射诱导结直肠癌SW480细胞发生上皮-间质转化(epithelial-mesenchymal transition,EMT)及其可能参与的信号转导通路。方法:分别采用0、2、4、6和8 Gy剂量的X射线照射SW480细胞。Transwell小室法检测X射线照射后对SW480细胞侵袭和迁移能力的影响;随后分别采用实时荧光定量PCR和蛋白质印迹法检测X射线照射对EMT上皮细胞标志物E-钙黏蛋白(E-cadherin,E-cad)和间质细胞标志物波形蛋白(vimentin)表达的影响,以及K-ras和Smad3 m RNA及蛋白表达水平的影响。结果:经X射线照射后,与对照组相比,各照射组中SW480细胞的侵袭和迁移能力均有提高(P < 0.05);实时荧光定量PCR和蛋白质印迹法检测结果显示,与对照组相比,各照射组SW480细胞中E-cad m RNA和蛋白的表达水平均被显著下调(P < 0.05),而vimentin m RNA和蛋白的表达水平则被明显上调(P < 0.05);K-ras m RNA及蛋白的表达水平下降(P < 0.05),而转化生长因子β1(transforming growth factor-β1,TGF-β1)/Smad3信号转导通路中Smad3 m RNA及蛋白的表达水平增高(P < 0.05)。结论:X线照射能够诱导结直肠癌细胞发生EMT,其诱导作用可能与TGF-β1/Smad3信号转导途径的激活有关。

Objective: To investigate the effect of X-ray irradiation on epithelial-mesenchymal transition(MET) in human colorectal cancer SW480 cells and its involved potential signaling pathway. Methods: SW480 cells were irradiated with different doses of X-ray(0, 2, 4, 6 and 8 Gy). The migration and invasion abilities of SW480 cells after irradiation were detected by Transwell method. The expression levels of E-cadherin(E-cad), vimentin, K-ras and Smad3 m RNAs and proteins in SW480 cells were detected by real-time fluorogenic quantitative-PCR and Western blotting, respectively. Results: The migration and invasion abilities of SW480 cells after irradiation with X-ray were increased as compared with that of the control cells(no irradiation)(P < 0.05). The m RNA and protein expression levels of E-cad and K-ras were significantly decreased while the expression levels of vimentin m RNA and protein were significantly increased after irradiation as compared with those of the control cells(all P < 0.05). The expression level of Smad3 m RNA and protein in transforming growth factor-β1(TGF-β1)/Smad3 signaling pathway were also increased(both P < 0.05) after irradiation. Conclusion: The results of this study support that X-ray irradiation can induce EMT of human colorectal cancer SW480 cells, and this effect may be related to the activation of TGF-β1/Smad3 signaling pathway.