RESUMEN
Objective To define the correlation between mutation of DNA-LigaseⅣ gene and radiosensitivity.Methods Nasopharyngeal squamous carcinoma cell line (CNE), lung adenocarcinoma cell line (SPC-A1) and breast adenocarcinoma cell line(MCF-7) after irradiation were assessed with specific biological parameters. Polymerase chain reaction, cloning and sequencing techniques were used to determine the sequence of DNA-LigaseⅣ gene in these three cell lines. Then the impact of homologous change and mutation on hydrophicity-hydrophobicity of genic products was analyzed.Results The surviving fractions derived from irradiation were different with more radiosensitivity in the CNE cell line than in the others. In three cell lines, the homology of LigaseⅣ gene were: 99.95%,99.99%,99.98%, respectively. Some mutations including transversion and transition were detected and led to alterations in the hydrophicity-hydrophobicity function of products. Higher radiosensitivity of CNE was associated with amino-acid substitutions: 313aa His→Arg,538aa Gly→Arg,579aa Lys→Arg and 585aa Asn→Ser.Conclusion These results suggest that LigaseⅣp play an important role in the ligation of DNA double strand breaks and certain mutations bring about changes in radiosensitivity.