ABSTRACT
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 mRNAs 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 mRNA and protein expression levels of E-cad and K-ras were significantly decreased while the expression levels of vimentin mRNA and protein were significantly increased after irradiation as compared with those of the control cells (all P < 0.05). The expression level of Smad3 mRNA and protein in transforming growth factor-p1 (TGF-p1)/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.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the change of expression level of metastasis suppressor gene Kiss-1 in the colorectal cancer cell line SW480 after radiation, and to determine its association with the proliferation and apoptosis of SW480 cells.</p><p><b>METHODS</b>SW480 cells were divided into control group (0 Gy) and study groups (2, 4, 6, 8 Gy). Cells in the study groups were irradiated by 6-MV X-ray radiation for 48 hours. Immunohistochemistry and real-time PCR methods were used to investigate the influence of radiation on Kiss-1 gene expression of SW480. Colony formation assay was used to detect the proliferation of SW480. Flow cytometry-Annexin- V/PI assay was used to observe the change of the apoptosis rate.</p><p><b>RESULTS</b>Compared with the control group, Kiss-1 protein expression increased after radiation of 6, 8 Gy (P<0.05), but no significant changes were observed after radiation of 2, 4 Gy(P>0.05). Kiss-1 gene mRNA level increased after radiation of 2, 4, 6 Gy, while no obvious change was observed for 8 Gy radiation. The apoptosis rates increased for 4, 6, 8 Gy radiation(P<0.05), however, there was no significant difference for 2 Gy radiation (P<0.05).</p><p><b>CONCLUSION</b>Radiation may increase Kiss-1 gene expression in SW480 cells, which results in decreases proliferation and increases apoptosis in residual surviving cells.</p>