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Micronucleus evaluation in mitogen-stimulated lymphocytes of PUVA treated patients
Zuhal Hamurcu1, Halil Demirtas, Ozcan Ascioglu
1Medical Biology and Genetics Department, Medical Faculty, Erciyes University, 38039 Kayseri, Turkey. med-biol@erciyes.edu.tr
Abstract:
PUVA describes the treatment of patients with psoralens plus an exposure to a source of UV light of 320-400 nm (UVA). Contradictory results have been reported on the chromosomal damage of PUVA when assayed by sister chromatid exchange (SCE) method. Micronucleus (MN) test is used to detect both clastogenic (breaking) and aneugenic (abnormal segregation) effect of physical/chemical agents on the chromosomes. No data have been found on the MN formation in the cells of PUVA treated patients. Frequency of micronuclei in 72 hours cultivated/mitogen-stimulated lymphocytes of patients have been evaluated at zero time and after 20, 40, 60 sessions of PUVA treatment. While the beginning MN frequency was approximately 0.22% (n=23), it raised to approximately 0.32 (n=23), approximately 0.42 (n=14) and approximately 0.53% (n=10) corresponding respectively to 20, 40 and 60 sessions. These sessions correspond reciprocally to 54+/-23, 172+/-48, 300+/-61 joules/cm2 of UVA and 13, 26, 39 mg/kg of 8-metoxypsoralen (8-MOP). While large interindividual variances were apparent, highly significant differences have been observed between initial MN frequency and after that of the 20, 40 and 60 sessions, (p = 0.000, p = 0.004, p = 0.005, reciprocally, Wilcoxon two-related samples test). The coefficient of correlation between MN frequency and UVA doses starting from zero to 60 sessions of treatment has been found as r = 0.61. This indicates a significant relationship between UVA doses and MN frequencies. However, MN inducibility and synergistic property of 8-MOP with UVA should be taken into account. Gradual MN increase during different sessions of PUVA treatment shows that--once appeared--a part of MN at least persist in the cells of patients from a few days to a few weeks. Smoking as a confounding factor seems to increase MN frequency (p = 0.053, Mann-Whitney U-test) in the beginning population, taken as the control population. This is the first report on the kinetics of MN formation during different sessions of PUVA treatment. Based on our results, we concluded that PUVA treatment causes a detectable chromosome damaging effect on the relatively profound cells/tissues of its human users. Therapists should be careful with its use, especially on the patients who may be more susceptible to carcinogenesis (e.g. immunosuppressed and/or elderly subjects).
Insights
Photochemotherapy with psoralens and UVA (PUVA) increases chromosomal damage, indicated by micronucleus (MN) formation, in patients. This study reveals a gradual increase in MN frequency with cumulative UVA exposure, suggesting PUVA poses a detectable genotoxic risk.
Area of Science:
- Genetics and Molecular Biology
- Dermatology
- Toxicology
Background:
- Psoralens plus Ultraviolet A (PUVA) therapy is used for skin conditions.
- Previous studies on PUVA's genotoxicity, using sister chromatid exchange (SCE), yielded conflicting results.
- The micronucleus (MN) test detects chromosomal damage (clastogenic and aneugenic effects).
Purpose of the Study:
- To investigate the formation of micronuclei (MN) in lymphocytes of patients undergoing PUVA treatment.
- To evaluate the kinetics of MN formation across multiple PUVA sessions.
- To assess the relationship between cumulative UVA dose and chromosomal damage.
Main Methods:
- Lymphocytes from PUVA-treated patients were cultured and stimulated with mitogen.
- Micronucleus (MN) frequency was assessed at baseline and after 20, 40, and 60 PUVA sessions.
- Statistical analyses included Wilcoxon signed-rank test and correlation analysis; smoking was considered as a covariate.
Main Results:
- Baseline MN frequency was approximately 0.22%, increasing significantly with PUVA sessions to 0.32% (20 sessions), 0.42% (40 sessions), and 0.53% (60 sessions).
- A significant positive correlation (r=0.61) was found between cumulative UVA dose and MN frequency.
- MN frequency showed a gradual increase and persistence, suggesting cumulative genotoxic effects; smoking appeared to elevate baseline MN frequency.
Conclusions:
- PUVA treatment induces detectable chromosomal damage in patients, as evidenced by increased MN formation.
- The genotoxic effect is dose-dependent on UVA exposure, with potential synergistic action from psoralens.
- Healthcare providers should exercise caution with PUVA, particularly for potentially susceptible individuals, due to its carcinogenic risk.