RESUMO
OBJECTIVE: 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. METHODS: 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. RESULTS: 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). CONCLUSION: Radiation may increase Kiss-1 gene expression in SW480 cells, which results in decreases proliferation and increases apoptosis in residual surviving cells.