Low doses of gamma ionizing radiation increase hprt mutant frequencies of TK6 cells without triggering the mutator phenotype pathway

Genetics and Molecular Biology

Flávio Monteiro Ayres¹  Aparecido Divino Da Cruz¹  Patricia Steele¹  Barry W. Glickman¹ 

[1] ,University of Victoria Department of Biology Centre for Environmental HealthVictoria BC ,Canada

关键词: mutator phenotype;    hprt;    microsatellite instability;    TK6 cells;    ionizing radiation;   

DOI  :  10.1590/S1415-47572006000300027

来源: SciELO

【 摘 要 】

The TK6 lymphoblastoid cell line is known to be mismatch repair (MMR) and p53 proficient. Deficiency in MMR results in a mutator phenotype characterized by microsatellite instability (MSI) and increased hprt mutant frequency (MF). Increased hprt MF is also a biomarker of effect for exposure to ionizing radiation. In order to test if a mutator phenotype could be induced by low doses of gamma ionizing radiation, an hprt cloning assay and a MSI investigation were performed after radiation exposure. The spontaneous MF was 1.6 x 10-6. The groups exposed to 0.2, 0.5 and 1.0 Gy had hprt MFs of 2.3, 3.3 and 2.2 x 10-6, respectively. The spontaneous MSI frequency per allele in non-selected cells was 5.4 x 10-3, as evidenced at the loci D11S35, nm23-H1, D8S135 and p53. MSI frequencies in the groups exposed to 0.2, 0.5 and 1.0 Gy were found to be < 4.7, < 7.7 and < 12 x 10-3, respectively. The frequencies of hprt mutants and MSI found in this study suggest that low doses of ionizing radiation increase hprt mutant frequency without triggering the mutator phenotype pathway.

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