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AZT induces high frequency, rapid amplification of centromeric DNA
Cytogenetics and Cell Genetics
|January 1, 1997
Summary
The drug 3'-azido-deoxythymidine (AZT) causes rapid amplification of telomere-like centromeric DNA in Chinese hamster ovary cells. This DNA amplification occurs without abnormal replication, suggesting a novel mechanism of chromosome instability.
Area of Science:
- Cytogenetics
- Molecular Biology
- Genetics
Background:
- 3 -azido-deoxythymidine (AZT), a reverse transcriptase inhibitor, integrates into telomeric and centromeric regions of chromosomes.
- AZT's impact on chromosome stability, particularly at centromeres and telomeres, requires further investigation.
Purpose of the Study:
- To investigate the effects of AZT on chromosome stability.
- To characterize the nature and formation of amplified DNA structures induced by AZT.
Main Methods:
- Cytogenetic analysis of Chinese hamster ovary (CHO) cell chromosomes.
- Analysis of BrdU incorporation to assess DNA replication during amplification.
Main Results:
- A high frequency of telomere-like centromeric DNA amplification was observed in AZT-treated CHO cells.
- Amplified structures consist of tandem arrays of centromeric repeats with telomeric sequences (TTAGGG)n, with 5-13 blocks per structure.
- Amplification occurs rapidly (1-2 cell cycles) with an incidence up to 2% and does not involve aberrant DNA replication.
Conclusions:
- AZT induces rapid amplification of centromeric DNA containing telomeric sequences.
- The amplification mechanism appears to involve excision and relocalization of existing centromeric regions rather than overreplication.
- This suggests a novel pathway for chromosome instability driven by AZT.