Estimating DNA repair by sequential evaluation of head and neck tumor radiation sensitivity using the comet assay

David J Terris, Edith Y. Ho, Hani Z. Ibrahim, Mary Jo Dorie, Mary S. Kovacs, Quynh T. Le, Albert C. Koong, Harlan A. Pinto, J. Martin Brown

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Background: The alkaline comet assay is a microelectrophoretic technique for detecting single-strand DNA breaks, and may be used as an indirect measure of hypoxia by determining the radiation sensitivity of individual cells. Objective: To assess the ability of the comet assay to estimate the rate of DNA repair after irradiation in patients with head and neck cancer. Methods: The comet assay was used to evaluate DNA damage in fine-needle aspirates of lymph nodes containing metastatic squamous cell carcinoma in patients with head and neck cancer 1, 2, and 3 minutes after treatment with 500 rad (5 Gy) of irradiation. The amount of DNA damage (measured as the "tail moment" of the comet) is proportional to the number of DNA single-strand breaks after irradiation, which in turn depends on the oxygen concentration in each cell. Results: The mean ± SD of the median tail moment of the 1-minute postirradiation comets was 29.4 ± 14.2 (n = 27). After 2 minutes, the mean median tail moment decreased to 25.4 ± 13.6 (n = 25), representing a mean decrease of 11.9% in those patients with both 1- and 2-minute comet assays. Assuming a linear rate of repair, this decrease in DNA damage corresponds to a repair half-life of 4.2 minutes. A 3-minute assay was also performed on samples from a smaller number of patients (n = 9), with a mean value not significantly different from that of the 2-minute assay of the samples from this group. Conclusions: The comet assay is a promising tool for evaluating radiation sensitivity in individual cells. The rate of DNA repair early after irradiation is consistent with data in the literature.

Original languageEnglish (US)
Pages (from-to)698-702
Number of pages5
JournalArchives of Otolaryngology - Head and Neck Surgery
Volume128
Issue number6
DOIs
StatePublished - Jan 1 2002
Externally publishedYes

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Comet Assay
Radiation Tolerance
DNA Repair
Neck
Head
DNA Damage
Single-Stranded DNA Breaks
Neoplasms
Head and Neck Neoplasms
Needles
Half-Life
Squamous Cell Carcinoma
Lymph Nodes
Oxygen

ASJC Scopus subject areas

  • Surgery
  • Otorhinolaryngology

Cite this

Estimating DNA repair by sequential evaluation of head and neck tumor radiation sensitivity using the comet assay. / Terris, David J; Ho, Edith Y.; Ibrahim, Hani Z.; Dorie, Mary Jo; Kovacs, Mary S.; Le, Quynh T.; Koong, Albert C.; Pinto, Harlan A.; Martin Brown, J.

In: Archives of Otolaryngology - Head and Neck Surgery, Vol. 128, No. 6, 01.01.2002, p. 698-702.

Research output: Contribution to journalArticle

Terris, David J ; Ho, Edith Y. ; Ibrahim, Hani Z. ; Dorie, Mary Jo ; Kovacs, Mary S. ; Le, Quynh T. ; Koong, Albert C. ; Pinto, Harlan A. ; Martin Brown, J. / Estimating DNA repair by sequential evaluation of head and neck tumor radiation sensitivity using the comet assay. In: Archives of Otolaryngology - Head and Neck Surgery. 2002 ; Vol. 128, No. 6. pp. 698-702.
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abstract = "Background: The alkaline comet assay is a microelectrophoretic technique for detecting single-strand DNA breaks, and may be used as an indirect measure of hypoxia by determining the radiation sensitivity of individual cells. Objective: To assess the ability of the comet assay to estimate the rate of DNA repair after irradiation in patients with head and neck cancer. Methods: The comet assay was used to evaluate DNA damage in fine-needle aspirates of lymph nodes containing metastatic squamous cell carcinoma in patients with head and neck cancer 1, 2, and 3 minutes after treatment with 500 rad (5 Gy) of irradiation. The amount of DNA damage (measured as the {"}tail moment{"} of the comet) is proportional to the number of DNA single-strand breaks after irradiation, which in turn depends on the oxygen concentration in each cell. Results: The mean ± SD of the median tail moment of the 1-minute postirradiation comets was 29.4 ± 14.2 (n = 27). After 2 minutes, the mean median tail moment decreased to 25.4 ± 13.6 (n = 25), representing a mean decrease of 11.9{\%} in those patients with both 1- and 2-minute comet assays. Assuming a linear rate of repair, this decrease in DNA damage corresponds to a repair half-life of 4.2 minutes. A 3-minute assay was also performed on samples from a smaller number of patients (n = 9), with a mean value not significantly different from that of the 2-minute assay of the samples from this group. Conclusions: The comet assay is a promising tool for evaluating radiation sensitivity in individual cells. The rate of DNA repair early after irradiation is consistent with data in the literature.",
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AU - Ho, Edith Y.

AU - Ibrahim, Hani Z.

AU - Dorie, Mary Jo

AU - Kovacs, Mary S.

AU - Le, Quynh T.

AU - Koong, Albert C.

AU - Pinto, Harlan A.

AU - Martin Brown, J.

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N2 - Background: The alkaline comet assay is a microelectrophoretic technique for detecting single-strand DNA breaks, and may be used as an indirect measure of hypoxia by determining the radiation sensitivity of individual cells. Objective: To assess the ability of the comet assay to estimate the rate of DNA repair after irradiation in patients with head and neck cancer. Methods: The comet assay was used to evaluate DNA damage in fine-needle aspirates of lymph nodes containing metastatic squamous cell carcinoma in patients with head and neck cancer 1, 2, and 3 minutes after treatment with 500 rad (5 Gy) of irradiation. The amount of DNA damage (measured as the "tail moment" of the comet) is proportional to the number of DNA single-strand breaks after irradiation, which in turn depends on the oxygen concentration in each cell. Results: The mean ± SD of the median tail moment of the 1-minute postirradiation comets was 29.4 ± 14.2 (n = 27). After 2 minutes, the mean median tail moment decreased to 25.4 ± 13.6 (n = 25), representing a mean decrease of 11.9% in those patients with both 1- and 2-minute comet assays. Assuming a linear rate of repair, this decrease in DNA damage corresponds to a repair half-life of 4.2 minutes. A 3-minute assay was also performed on samples from a smaller number of patients (n = 9), with a mean value not significantly different from that of the 2-minute assay of the samples from this group. Conclusions: The comet assay is a promising tool for evaluating radiation sensitivity in individual cells. The rate of DNA repair early after irradiation is consistent with data in the literature.

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