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Updated: Jun 1, 2026
An Automated Method to Perform The In Vitro Micronucleus Assay using Multispectral Imaging Flow Cytometry
Published on: May 13, 2019
Micronuclei induced by reverse transcriptase inhibitors in mononucleated and binucleated cells as assessed by the
Eloir D Lourenço1, Viviane S do Amaral, Mauricio Lehmann
1Programa de Pós-Graduação em Diagnóstico Genético e Molecular, Universidade Luterana do Brazil, Canoas, RS Brazil.
Abstract:
This study evaluated the clastogenic and/or aneugenic potential of three nucleoside reverse transcriptase inhibitors (zidovudine - AZT, lamivudine - 3TC and stavudine - d4T) using the cytokinesis-block micronucleus (CBMN) assay in human lymphocyte cultures. All three inhibitors produced a positive response when tested in binucleated cells. The genotoxicity of AZT and 3TC was restricted to binucleated cells since there was no significant increase in the frequency of micronuclei in mononucleated cells. This finding indicated that AZT and 3TC caused chromosomal breakage and that their genotoxicity was related to a clastogenic action. In addition to the positive response observed with d4T in binucleated cells, this drug also increased the frequency of micronuclei in mononucleated cells, indicating clastogenic and aneugenic actions. Since the structural differences between AZT and 3TC and AZT and d4T involve the 3' position in the 2'-deoxyribonucleoside and in an unsaturated 2',3',dideoxyribose, respectively, we suggest that an unsaturated 2', 3', dideoxyribose is responsible for the clastogenic and aneugenic actions of d4T.
Insights
Three nucleoside reverse transcriptase inhibitors (zidovudine, lamivudine, and stavudine) were tested for genotoxicity. Stavudine showed both clastogenic and aneugenic potential, unlike the others which were only clastogenic.
Area of Science:
- Toxicology
- Molecular Biology
- Genetics
Background:
- Nucleoside reverse transcriptase inhibitors (NRTIs) are crucial for HIV treatment.
- Assessing the genotoxic potential of NRTIs is vital for patient safety.
- Previous studies have raised concerns about the long-term effects of NRTIs.
Purpose of the Study:
- To evaluate the clastogenic and aneugenic potential of three NRTIs: zidovudine (AZT), lamivudine (3TC), and stavudine (d4T).
- To investigate the mechanisms of genotoxicity induced by these drugs in human lymphocytes.
- To correlate structural differences with observed genotoxic effects.
Main Methods:
- The cytokinesis-block micronucleus (CBMN) assay was employed.
- Human lymphocyte cultures were utilized.
- Micronuclei frequency in mononucleated and binucleated cells was analyzed.
Main Results:
- All three NRTIs (AZT, 3TC, d4T) induced a positive response in binucleated cells, indicating clastogenic effects.
- AZT and 3TC primarily exhibited clastogenic action, with no significant increase in mononucleated cells.
- d4T demonstrated both clastogenic and aneugenic actions, increasing micronuclei in both cell types.
Conclusions:
- The genotoxicity of AZT and 3TC is mainly due to chromosomal breakage (clastogenic action).
- Stavudine (d4T) possesses both clastogenic and aneugenic potential.
- The unsaturated 2',3'-dideoxyribose structure in d4T is suggested to be responsible for its combined clastogenic and aneugenic effects.
