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The radioenhancement of two human head and neck squamous cell carcinomas by 2'-2' difluorodeoxycytidine (gemcitabine; dFdC) is mediated by an increase in radiation-induced residual chromosome aberrations but not residual DNA DSBs.
- Source :
-
Mutation research [Mutat Res] 2003 Jun 19; Vol. 527 (1-2), pp. 15-26. - Publication Year :
- 2003
-
Abstract
- Purpose: The present study aimed at investigating if 2'-2' difluorodeoxycytidine (dFdC) radioenhancement was mediated by an effect on induction and/or repair of radiation-induced DNA DSBs and chromosome aberrations in cells with different intrinsic radiosensitivity.<br />Methods: Confluent human head and neck squamous cell carcinoma cell lines designated SCC61 and SQD9 were treated with 5 microM dFdC for 3 or 24 h prior to irradiation. DNA DSBs induction and repair were analyzed by PFGE. Radiation-induced chromosome aberrations were examined with a FISH technique.<br />Results: In both cell lines, dFdC did not modify radiation-induced DNA DSBs in a dose range between 0 and 40 Gy. After a single dose of 40 Gy, dFdC affected neither the kinetic of repair nor the residual amount of DNA DSBs up to 4 h after irradiation. Whereas dFdC did not increase the induction of chromosome aberrations, after a single dose of 5 Gy, the percentage of aberrant cells and the number of aberrations per aberrant cells were significantly higher in combination with dFdC.<br />Conclusion: Our data suggest that under experimental conditions yielding substantial radioenhancement, dFdC decreases the repair of genomic lesions inducing secondary chromosome breaks but has no effect on DNA DSBs repair as measured by PFGE.
- Subjects :
- Carcinoma, Squamous Cell pathology
Combined Modality Therapy
DNA Damage drug effects
DNA Damage radiation effects
DNA, Neoplasm drug effects
DNA, Neoplasm radiation effects
Head and Neck Neoplasms pathology
Humans
Radiation Tolerance
Radiation, Ionizing
Time Factors
Tumor Cells, Cultured
Gemcitabine
Antineoplastic Agents pharmacology
Carcinoma, Squamous Cell drug therapy
Chromosome Aberrations drug effects
Chromosome Aberrations radiation effects
Deoxycytidine analogs & derivatives
Deoxycytidine pharmacology
Head and Neck Neoplasms drug therapy
Head and Neck Neoplasms radiotherapy
Radiation-Sensitizing Agents pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 0027-5107
- Volume :
- 527
- Issue :
- 1-2
- Database :
- MEDLINE
- Journal :
- Mutation research
- Publication Type :
- Academic Journal
- Accession number :
- 12787910
- Full Text :
- https://doi.org/10.1016/s0027-5107(03)00053-8