Carcinogenesis Advance Access published online on March 6, 2007
Carcinogenesis, doi:10.1093/carcin/bgm029
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A Modified Host-Cell Reactivation Assay to Measure Repair of Alkylating DNA damage for Assessing Risk of Lung Adenocarcinoma
Department of Epidemiology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, 77030
Requests for reprints: Qingyi Wei, Department of Epidemiology, Unit 1365, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030. Phone: 713-792-3020; Fax: 713-563-0999; E-mail: qwei{at}mdanderson.org.
The nicotine-derived nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces lung adenocarcinoma through formation of DNA adducts. Our previous research on susceptibility to tobacco-induced carcinogenesis focused on benzo[a]pyrene diol epoxide (BPDE) as the in vitro mutagen for phenotype measurements of DNA repair capacity (DRC) in mammalian cells. Here, we present a modified host-cell reactivation (HCR) assay to measure lymphocytic DRC for alkylating DNA damage as is induced by the tobacco-specific nitrosamine, NNK. We substituted dimethyl sulfate (DMS) to create alkylating damage in pCMVluc plasmid DNA and established the damage-repair dose-response curves in both normal and nucleotide excision repair (NER)-deficient lymphoblastoid cell lines and in phytohemagglutinin (PHA)-stimulated primary lymphocytes. We then successfully measured the DRC in PHA-stimulated lymphocytes from 48 patients with lung adenocarcinoma and 45 cancer-free controls and tested our hypothesis that lower DRC for alkylating damage is associated with an increased risk of lung adenocarcinoma. The cases exhibited a lower mean DRC than did the controls. A greater than three-fold increased risk (odds ratio = 3.21; 95% confidence interval=1.25-8.21) was found for those with DRC levels below the control median. There was no correlation between the DRC measured with this DMS-HCR assay and that from the parallel BPDE-HCR assay. Interestingly, risk increased to more than 10-fold for those with suboptimal DRC measured by both DMS- and BPDE-HCR assays. We conclude that variability in DRC is a risk factor for lung cancer and our results provide proof of principle for a new assay that can assess DRC for NNK-induced damage.
Key Words: Alkylating DNA adducts • DNA damage • DNA repair • Host-Cell Reactivation, Lung Adenocarcinoma
Grant support: NIH grants CA55769 and CA70907 (M.R. Spitz); ES11740 and CA100264 (Q. Wei), CA16672 and Lung SPORE (The University of Texas M. D. Anderson Cancer Center), and FAMRI grant of the Flight Attendant Medical Research Institute (M.R. Spitz).
Received November 15, 2006; revised January 10, 2007; accepted February 5, 2007.