Abstract 4199: Genetic variation in the in vitro genotoxic response to glycidamide and gene expression of DNA repair genes
Authors: Marta Pingarilho, Nuno G. Oliveira, Célia Martins, Bruno C. Gomes, Ana S. Fernandes, Vanda Martins, Anatália R. Silva, José Rueff, Jorge F. Gaspar
Journal: Cancer Research (2011)

Abstract Acrylamide (AA) is a suspected human carcinogen generated in carbohydrate-rich foodstuff upon heating. Glycidamide (GA), formed via epoxidation presumably mediated by cytochrome P450 2E1, is thought to be the active metabolite that plays a central role in AA genotoxicity. The high levels of AA that are orally consumed could be an additional factor for global cancer risk. However, cancer risk estimation in population is still problematic and the mechanisms of DNA repair triggered by GA are still poorly understood. The aim of this work was to evaluate the role of DNA repair genes in the genotoxicity induced by GA in human cells, using complementary methodologies. For this purpose, the effect of GA (250 µM) in cultured human lymphocytes from healthy non-smoker individuals (n=13) was assessed using the sensitive sister-chromatid exchange assay (SCE, 46 h in vitro exposure). GA was found to be genotoxic, with a large inter-individual variation. Therefore we studied the possible influence of individual genetic polymorphisms of key genes codifying for DNA repair enzymes related to the BER (XRCC1, OGG1, PARP1, PARP4, APEX1 and MUTYH), NER (RAD23B, ERCC1, ERCC2, ERCC4, ERCC5, ERCC6 and XPC) and HRR (RAD51, NBS, XRCC3 and XRCC2) pathways. No relevant associations between SCE/cell levels and the individual genetic polymorphisms were found. However, the only individual with the ERCC1 Q504K polymorphism revealed a significant increase in GA-induced levels of SCE/cell (p&amp;lt;0.03). We further studied the effect of the same concentration of GA in peripheral white blood cells from healthy individuals (n=25) using the comet assay (CA, 1 hour in vitro incubation). GA also showed to be genotoxic. The % DNA in Tail for all individuals was analysed considering the abovementioned polymorphisms. In this assay, the MUTYH H335Q was found to influence the repair capacity of GA, being the variant genotype associated with an increased damage in the comet assay (6.1± 1.7 heterozygous versus 11.9 ± 1.8 homozygous variant; p&amp;lt;0.001). Finally, a different strategy focusing on the role of DNA repair enzymes upon GA treatment was used. The non-malignant mammary cell line MCF10A was exposed to GA (10 µM) for 24 h and gene expression was studied using RT2 ProfilerTM PCR Array: Human DNA Damage Signalling Pathway by SABiosciencesTM. Concerning gene expression results, GA at this lower concentration level did not influence the expression of the genes considered when compared to respective non-treated controls. Further studies should be conducted in order to test other exposure periods and use other human cell types. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4199. doi:10.1158/1538-7445.AM2011-4199