X-ray-induced epithelial-mesenchymal transition in SW480 colorectal cancer cells and its potential mechanisms.

PURPOSE: The purpose of this study was to investigate the relation between X-ray irradiation and epithelial-mesenchymal transition (EMT), as well as the potential mechanisms of X-ray-induced EMT in SW480 colorectal cancer (CRC) cells.

METHODS: It is well known that EMT plays a critical role in invasive and metastatic of colorectal cancer progression. However, the possible role of X-ray irradiation on EMT in colorectal cancer is widely disputed and its potential mechanisms are unclear. SW480 CRC were irradiated (0, 2, 4, 6, 8 Gy) and cultured for 48 hrs, and then the cellular morphology was observed. Protein and mRNA expressions were examined by Western blot and QRT-PCR. Cell migratory and invasive capacity was evaluated by Transwell assay.

RESULTS: In the 2, 4, 6, 8 Gy groups, SW480 CRC exhibited a classical mesenchymal phenotype compared with the 0 Gy group. The expression of E-cadherin was significantly decreased, while the expression of vimentin and Smad3 was significantly increased in the 2, 4, 6, 8 Gy groups (p<0.05) compared with the 0 Gy group; still, the expression of K-ras decreased in the 4, 6, 8 Gy groups (p<0.05) compared with the 0 and 2 Gy groups. Furthermore, the cell migration and invasion capacity was significantly enhanced in the 4 and 8 Gy groups compared with the 0 Gy group (p<0.05).

CONCLUSION: These results support the fact that X-ray irradiation can induce EMT through promoting Vimentin and Smad3 expression in SW480 CRC cells.