Relationships between DNA incorporation, mutant frequency, and loss of heterozygosity at the TK locus in human lymphoblastoid cells exposed to 3'-azido-3'-deoxythymidine
| Autor: | Quanxin Meng, Ting Su, Miriam C. Poirier, Ofelia A. Olivero, Xinxin Ding, Xiaochu Shi, Vernon E Walker |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Anti-HIV Agents
Cell Survival viruses Loss of Heterozygosity Biology Toxicology medicine.disease_cause Thymidine Kinase Cell Line Loss of heterozygosity chemistry.chemical_compound immune system diseases medicine Humans heterocyclic compounds Lymphocytes Carcinogen Southern blot Dose-Response Relationship Drug Lymphoblast virus diseases DNA biochemical phenomena metabolism and nutrition Virology Molecular biology chemistry Thymidine kinase Mutation Carcinogenesis Zidovudine Genotoxicity Mutagens |
| Zdroj: | Toxicological sciences : an official journal of the Society of Toxicology. 54(2) |
| ISSN: | 1096-6080 |
| Popis: | 3'-Azido-3'-deoxythymidine (AZT), a thymidine analogue widely used in the treatment of AIDS patients and for prevention of the onset of AIDS in HIV-seropositive individuals, causes tumors in mice exposed as adults or in utero. The purpose of this study was to investigate the potential mechanisms of AZT mutagenicity and carcinogenicity by quantifying the incorporation of AZT into cellular DNA, measuring AZT-induced thymidine kinase (TK) mutant frequencies (Mfs), and determining the percentage of loss of heterozygosity (LOH) in spontaneous or AZT-induced TK mutants in the human lymphoblastoid cell line, TK6. Cells were exposed to 300 microM AZT for 0, 1, 3, or 6 days, or to 0, 33, 100, 300, or 900 microM AZT for 3 days (n = 5 flasks/group). The effects of exposure concentration on incorporation of AZT into cellular DNA were evaluated by an AZT radioimmunoassay, and the effects of duration and concentration of AZT exposure on the TK Mfs were assessed by a cell-cloning assay. AZT was incorporated into DNA in a dose-related manner at concentrations up to 300 microM, above which no further increase was observed. TK Mf increased with the extended duration and with incremental concentrations of AZT exposure. There was a positive correlation (P = 0.036, coefficient = 0.903) between AZT-DNA incorporation and AZT-induced TK Mfs, suggesting that AZT incorporation into cellular DNA has a direct role in the genotoxicity of AZT. Southern blot analyses indicated that 84% (6.2 x 10(-6)/7.4 x 10(-6)) of AZT-induced mutants were attributable to LOH, consistent with the known mechanism of AZT as a DNA chain terminator. Considering the importance of LOH in human carcinogenesis, AZT-induced LOH warrants further study. |
| Databáze: | OpenAIRE |
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