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Increased mutagen sensitivity in human cultured fibroblasts with constitutively high micronucleus levels
B Rümmelein1, O Drieschner, U Ehlert
1Unit of Toxicogenetics, University of Hamburg, Germany.
Abstract:
The induction of micronuclei (MN) by incubation with different mutagenic agents was tested in diploid fibroblast cultures obtained from 15 probands with constitutively high MN rates (15.75-77.25 MN/500 cells; average 36.27 +/- 17.60 MN) and 15 probands (controls) with low MN rates (4-13.75 MN/500 cells; average 8.97 +/- 2.73 MN). In order to find out whether fibroblast cultures of individuals with increased spontaneous MN levels exhibit an increased sensitivity to various agents with different genotoxic mechanisms, we studied the induction of MN in these cell cultures by ultraviolet (UV) irradiation, mitomycin C (MMC), N-methyl-N-nitro-N-nitrosoguanidine (MNNG) and benzo-(a)pyrene-diol-expoxid (BPDE). In addition, we tested aphidicolin (APC), a polymerase alpha inhibitor, which is a potent inducer of common fragile sites. Probands with spontaneously high MN showed an significantly increased sensitivity to UV (p less than or equal to 0.005), MMC (p less than or equal to 0.005), and BPDE (p less than or equal to 0.005). No significant differences were found for MNNG and APC as compared to controls.
Insights
Individuals with high spontaneous micronuclei (MN) rates show increased sensitivity to genotoxic agents like UV, mitomycin C, and BPDE. This suggests a potential link between elevated MN levels and heightened cellular susceptibility to DNA damage.
Area of Science:
- Genetics
- Toxicology
- Cell Biology
Background:
- Micronuclei (MN) formation is a biomarker for genotoxicity and chromosomal instability.
- Elevated spontaneous MN rates in individuals may indicate underlying genetic instability or increased susceptibility to mutagens.
Purpose of the Study:
- To investigate whether fibroblast cultures from individuals with high spontaneous micronuclei (MN) rates exhibit increased sensitivity to various genotoxic agents.
- To compare the response of high-MN and control fibroblast cultures to UV irradiation, mitomycin C (MMC), N-methyl-N-nitro-N-nitrosoguanidine (MNNG), benzo-(a)pyrene-diol-expoxid (BPDE), and aphidicolin (APC).
Main Methods:
- Diploid fibroblast cultures were obtained from 15 probands with high spontaneous MN rates and 15 controls with low MN rates.
- Cells were exposed to different genotoxic agents: UV irradiation, MMC, MNNG, BPDE, and APC.
- Micronuclei induction was quantified to assess cellular sensitivity to each agent.
Main Results:
- Fibroblast cultures from probands with high spontaneous MN showed significantly increased sensitivity to UV irradiation (p ≤ 0.005), MMC (p ≤ 0.005), and BPDE (p ≤ 0.005).
- No significant differences in MN induction were observed between high-MN and control groups when treated with MNNG or APC.
- These findings indicate a differential sensitivity to specific genotoxic mechanisms in individuals with elevated baseline MN levels.
Conclusions:
- Individuals with constitutively high micronuclei rates exhibit heightened sensitivity to certain genotoxic agents, particularly those causing DNA damage via UV, MMC, and BPDE pathways.
- The study highlights a potential biomarker role for spontaneous MN rates in identifying individuals with increased susceptibility to specific types of DNA damage.
- Further research is warranted to elucidate the precise mechanisms underlying this increased sensitivity and its implications for health risks.