| Objective: to study the correlation between the number of radiation-induced translocations of chromosome 2 and the cell survival fraction after radiation using fluorescence in situ hybridization , and discuss the feasibility to predict the radiosensitivity of human colorectal cancer cell using FISH . Methods: In vitro study : Two human colorectal cancer cell lines Lovo and SW480 were cultivated and the cell survival fraction after radiation by X-ray with 0,2,4,6 Gy was detected by means of clonogenic assay respectively. The cell survival curve was drawn . At the mean time the number of radiatio-induced-translocations of chromsome 2 was observed using FISH and chromosome 2 painting probe at the twenty-fourth hour after radiation . Then the correlation between the number of chromosome aberrations and the cell survival fraction was observed. In vivo study : The cell Lovo and SW480 were transplanted into subcutaneous tissue of nude mice , and 12 animal models were obtained respectively . The implanted tumors were irradiated with 10 Gy when their diameters were 4-6mm. implanted tumors of 6 mice were resected at the twenty-fourth hour after radiation ,made into suspention liquid , and cultivated in vitro in short time .The number of chromosomal translocations of the 2 implanted tumors was compared using FISH and chromosome 2 painting probe . To the rest 6 mice each group , the diameter of implanted tumors was measured every 2 days , and then the grow curve was drawn through which the radiosensitivity of the 2 cell lines was compared . Results: The cell survival curve showed that the radiosensitivity of the cellline Lovo was higher than SW480 . A dose-dependent increase in radiation-induced chromosome aberrations was observed in the 2 cell lines . On the same dose , the number of chromosome 2 aberration in Lovo cell was higher than SW480 significantly . By integrating the experimental data of the 2 cell lines , A good correlation (r=-0.89,P<0.05) was found between cell survival and the number of radiation-induced translocations of chromosome 2 . The grow curve of implanted tumor after radiation showed that the sensitivity of Lovo cell was higher than SW480 . The result of FISH detection to implanted tumor resected indicated the number of chromosome 2 aberration of Lovo cell was higher than SW480 significantly (P<0.05). Conclusions: Fluorescence In Situ Hybridization can be used to predict theintrinsic radiosensitivity of human colorectal cancer cell conveniently andreliably . It provides important references for the selection of radiotherapyin the patients suffering colorectal cancer clinicaly . |
