Cytogenetic Challenge Assays for Assessment of DNA Repair Capacities
Different challenge assays have been used to investigate cellular responses following exposure to DNA damaging agents. Our protocol uses X- or γ-rays or ultraviolet light to challenge cells to repair the induced damage, and chromosome aberrations as a biomarker to indicate DNA repair proficiency. The assay was used successfully to demonstrate base- and nucleotide-excision repair deficiency in certain polymorphic DNA repair genes, namely XRCC1 751Gln and XPD 312Asn, respectively. In addition, populations with elevated exposure to certain environmental mutagenic agents—cigarette smokers, pesticide sprayers, and residents who lived near uranium mining and milling sites—showed DNA repair deficiency. Because expression of chromosome aberrations is associated with a significantly increased incidence of both cancer morbidity and mortality, the challenge assay may be useful in predicting cancer risk. The protocol for the assay is straightforward and the data have practical applications.
Key WordsChallenge assays DNA repair mutagen sensitivity population monitoring
Many colleagues have made significant contributions to the development of the challenge assay. Although we are not able to provide a comprehensive list of these colleagues we would like to show our appreciation to the late Dr. T. C. Hsu, Dr. Julian Preston, Dr. Marvin Legator, Dr. Jonathan Ward, Jr., Dr. Moon Heo, and Mrs. Sylvia Szucs.
- 1.Spitz, M. R., Fueger, J. J., Halabi, S., Schantz, S. P., Sampe, D., and Hsu, T.C. (1993) Mutagen sensitivity in upper aerodigestive tract cancer: a case-control analysis. Cancer Epidemiol. Biom. Prev. 2, 329–333.Google Scholar
- 13.Zhou, W., Liu, G., Miller, D. P., Thurston, S. W., Xu, L., and Wain, J. C. (2003) Polymorphisms in the DNA repair genes XRCC1 and ERCC2, smoking and lung cancer risk. Cancer Epid. Biomarkers Prev. 12, 359–365.Google Scholar
- 18.Cebulska-Wasilewska, A., Panek, A., Zabinski, Z., Moszczynski, P., and Au, W.W. (2005) Influence of mercury vapours on lymphocytes in vivo and on their susceptibility to UV-C and X-rays, and repair efficiency in vitro. Mutat. Res., in press.Google Scholar
- 21.Au, W. W. (1991) Monitoring human population for the effects of radiation and chemical exposures using cytogenetic techniques, in Occupational Medicine: State of the Art Reviews (Wilkinson, G., ed.), Hanley and Belfus, Philadelphia, PA, pp. 597–611.Google Scholar
- 22.Au, W. W., Badary, O., and Heo, M. Y. (2001) Cytogenetic assays for monitoring populations exposed to environmental mutagens, in Occupational Medicine: State of the Art Reviews (Wilkinson, G. ed.), Vol. 16, Hanley and Belfus, Inc., pp. 345–357.Google Scholar
- 24.Au, W. W., (2000) Strategies for conducting human population monitoring studies. NATO Sci. A Life Sci. 313, 86–93.Google Scholar