title: Development of APE1 enzymatic DNA repair assays: low APE1 activity is associated with increase lung cancer risk.
abstract: The key role of DNA repair in removing DNA damage and minimizing mutations makes it an attractive target for cancer risk assessment and prevention. Here we describe the development of a robust assay for apurinic/apyrimidinic (AP) endonuclease 1 (APE1; APEX1), an essential enzyme involved in the repair of oxidative DNA damage. APE1 DNA repair enzymatic activity was measured in peripheral blood mononuclear cell protein extracts using a radioactivity-based assay, and its association with lung cancer was determined using conditional logistic regression with specimens from a population-based case-control study with 96 lung cancer cases and 96 matched control subjects. The mean APE1 enzyme activity in case patients was 691 [95% confidence interval (CI) = 655-727] units/ng protein, significantly lower than in control subjects (mean = 793, 95% CI = 751-834 units/ng protein, P = 0.0006). The adjusted odds ratio for lung cancer associated with 1 SD (211 units) decrease in APE1 activity was 2.0 (95% CI = 1.3-3.1; P = 0.002). Comparison of radioactivity- and fluorescence-based assays showed that the two are equivalent, indicating no interference by the fluorescent tag. The APE1Asp148Glu SNP was associated neither with APE1 enzyme activity nor with lung cancer risk. Taken together, our results indicate that low APE1 activity is associated with lung cancer risk, consistent with the hypothesis that 'bad DNA repair', rather than 'bad luck', is involved in cancer etiology. Such assays may be useful, along with additional DNA repair biomarkers, for risk assessment of lung cancer and perhaps other cancers, and for selecting individuals to undergo early detection techniques such as low-dose CT.
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel, Department of Community Medicine and Epidemiology, Carmel Medical Center, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, and Clalit Health Services National Cancer Control Center, Haifa, Israel, Department of General Thoracic Surgery, Rambam Health Care Campus, Haifa, Israel and Biostatistics Unit, Gertner Institute for Epidemiology and Public Health Policy Research, Sheba Medical Center, Tel Hashomer 52621, Israel.
authors.forename: Ziv
authors.initials: Z
authors.lastname: Sevilya
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel, Department of Community Medicine and Epidemiology, Carmel Medical Center, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, and Clalit Health Services National Cancer Control Center, Haifa, Israel, Department of General Thoracic Surgery, Rambam Health Care Campus, Haifa, Israel and Biostatistics Unit, Gertner Institute for Epidemiology and Public Health Policy Research, Sheba Medical Center, Tel Hashomer 52621, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Leitner-Dagan
authors.affiliation: Department of Community Medicine and Epidemiology, Carmel Medical Center, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, and Clalit Health Services National Cancer Control Center, Haifa, Israel.
authors.forename: Mila
authors.initials: M
authors.lastname: Pinchev
authors.affiliation: Department of General Thoracic Surgery, Rambam Health Care Campus, Haifa, Israel and.
authors.forename: Ran
authors.initials: R
authors.lastname: Kremer
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel, Department of Community Medicine and Epidemiology, Carmel Medical Center, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, and Clalit Health Services National Cancer Control Center, Haifa, Israel, Department of General Thoracic Surgery, Rambam Health Care Campus, Haifa, Israel and Biostatistics Unit, Gertner Institute for Epidemiology and Public Health Policy Research, Sheba Medical Center, Tel Hashomer 52621, Israel.
authors.forename: Dalia
authors.initials: D
authors.lastname: Elinger
authors.affiliation: Department of Community Medicine and Epidemiology, Carmel Medical Center, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, and Clalit Health Services National Cancer Control Center, Haifa, Israel.
authors.forename: Flavio
authors.initials: F
authors.lastname: Lejbkowicz
authors.affiliation: Department of Community Medicine and Epidemiology, Carmel Medical Center, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, and Clalit Health Services National Cancer Control Center, Haifa, Israel.
authors.forename: Hedy S
authors.initials: HS
authors.lastname: Rennert
authors.affiliation: Biostatistics Unit, Gertner Institute for Epidemiology and Public Health Policy Research, Sheba Medical Center, Tel Hashomer 52621, Israel.
authors.forename: Laurence S
authors.initials: LS
authors.lastname: Freedman
authors.affiliation: Department of Community Medicine and Epidemiology, Carmel Medical Center, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, and Clalit Health Services National Cancer Control Center, Haifa, Israel.
authors.forename: Gad
authors.initials: G
authors.lastname: Rennert
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel, Department of Community Medicine and Epidemiology, Carmel Medical Center, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, and Clalit Health Services National Cancer Control Center, Haifa, Israel, Department of General Thoracic Surgery, Rambam Health Care Campus, Haifa, Israel and Biostatistics Unit, Gertner Institute for Epidemiology and Public Health Policy Research, Sheba Medical Center, Tel Hashomer 52621, Israel zvi.livneh@weizmann.ac.il tamar.paz-elizur@weizmann.ac.il.
authors.forename: Tamar
authors.initials: T
authors.lastname: Paz-Elizur
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel, Department of Community Medicine and Epidemiology, Carmel Medical Center, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, and Clalit Health Services National Cancer Control Center, Haifa, Israel, Department of General Thoracic Surgery, Rambam Health Care Campus, Haifa, Israel and Biostatistics Unit, Gertner Institute for Epidemiology and Public Health Policy Research, Sheba Medical Center, Tel Hashomer 52621, Israel zvi.livneh@weizmann.ac.il.
authors.forename: Zvi
authors.initials: Z
authors.lastname: Livneh
mesh_terms: D016022:Case-Control Studies; D004249:DNA Damage / Q000235:genetics; D004260:DNA Repair / Q000235:genetics*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005453:Fluorescence; D020022:Genetic Predisposition to Disease; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology; D008168:Lung / Q000201:enzymology / Q000473:pathology; D008175:Lung Neoplasms / Q000201:enzymology* / Q000453:epidemiology* / Q000235:genetics; D008297:Male; D020641:Polymorphism, Single Nucleotide; D012306:Risk
chemical_list: C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase