Abstract 306: DNA Repair Enzyme Signature of a cohort of 100 healthy individuals using peripheral blood mononuclear cells: In the search of cancer susceptibility biomarkers

It is well established that mutations and combinations of polymorphisms in DNA Repair genes contribute to cancer occurrence. However the relationship between genotypes and cancer is not straightforward. As a matter of fact, individuals’ cancer susceptibility also depends on their genotoxic exposure history, age and lifestyle. In this context, functional DNA-repair tests better account for DNA Repair complexity and constitute powerful strategies to characterize effective individuals DNA Repair capacity. Currently available tools interrogate very limited aspects of DNA Repair mechanism and more informative assays are urgently needed. In humans Base Excision Repair (BER) involves several glycosylases that have the ability to recognize and cleave a set of small base lesions resulting from oxidation, alkylation, or deamination of normal bases, with the help of an AP endonuclease (APE1) that removes abasic sites. To precisely characterize the BER pathway and offer better chance to identify individuals with altered DNA repair capacities, we developed a comprehensive approach that quantifies simultaneously several BER repair enzymes in cell extracts. This multiplexed biochip version of the well-known oligonucleotide cleavage assay was implemented to characterize the DNA Repair Enzyme Signature of a cohort of 100 healthy individuals (50% males and 50% females, ranging in age from 18 to 70 years). All were non-smokers. Two 8 mL blood samples were taken the first day and another one one week apart. Whole cell extracts were prepared from the subjects Peripheral Blood Mononuclear Cells (PBMCs) and protein concentration was determined. Assay robustness was assessed and the inter- and intra-individual BER variability was also determined. We observed a large inter-individual variability in DNA repair capacities. We demonstrated that there was a gender-specific impact of aging on certain DNA Repair activities. Thanks to the multiplexed approach, using hierarchical clustering and principal component analysis, we gained new information on the different glycosylase activities co-regulations and assigned the samples to distinct subpopulation clusters characterized by their DNA Repair Signature. Here again, males and females exhibited different features. We demonstrated that our powerful assay is robust, can be implemented on a large scale and could be used for population studies to identify biomarkers of exposure and biomarkers of cancer susceptibility. We thank GRAVIT and CEA program Technologies for Health for financial support. Citation Format: Sylvie Sauvaigo, Lise Jacqueroux, Benoit Pitiot, Sylvain Caillat, Nicolas Gonnet, Jean-Luc Cracowski. DNA Repair Enzyme Signature of a cohort of 100 healthy individuals using peripheral blood mononuclear cells: In the search of cancer susceptibility biomarkers. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 306. doi:10.1158/1538-7445.AM2014-306