A collaborative research study between NTU professors and researchers across universities in Taiwan to first quantitatively analyze a new risk-associated biomarker for acrylamide exposures from tobacco smoke and diet. BACKGROUND INFORMATION: Acrylamide (AA) is an industrial chemical widely used in the production of polymers and copolymers for many applications. It was later found that in addition to occupational exposures, the general public also may be exposed to AA from foods processed at high temperatures and mainstream cigarettes. Exposure to AA is found to be associated with neurotoxicity and reproductive toxicity. Based on established evidence from animal studies and inconclusive epidemiology studies, AA has been classified as probable human carcinogen (Group 2A) by the International Agency for Research on Cancer. Current understanding of AA’s mechanism in causing cancer suggests that absorbed AA can be metabolically activated to glycidamide (GA), which can react with DNA-bases to form DNA adducts, leading to potential DNA damage and cancer. Of the nine identified AA-induced DNA adducts in mice, N7-(2-carbamoyl-2-2hydroxyethyl)-guanine (N7-GAG) was the most abundant adduct. Although N7-GAG has not been analyzed in DNA from human tissues, it may be depurinated to form purine sites in the DNA backbone, hence excreted in the urine. As urine samples are easy to assess with non-invasive methods, the analysis of urinary DNA adducts may serve as exposure- and probable cancer risk-associated biomarkers in molecular epidemiology studies. ABOUT THE RESEARCH: NTU professors and researchers from other universities conducted a study titled “Potential Association of Urinary N7‑(2-Carbamoyl-2-hydroxyethyl) Guanine with Dietary Acrylamide Intake of Smokers and Nonsmokers” and the study was recently published in Chemical Research in Toxicology for its significant contribution. To confirm AA’s genotoxicity and its active species in humans, Professor Kuen-Yuh Wu and his research colleagues aimed to develop a method to analyze N7-GA-GAG in urine in order to assess the exposure to AA from tobacco smoke and diet. Urinary samples were collected from both smokers and non-smokers who have occupational exposure to AA. Isotope-dilution liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was used for the analysis of the samples. Other metabolites such as urinary AAMA and cotinine were also measured with LC-MS/MS for comparisons with the levels of urinary N7-GAG using statistical analysis to better understand the association between the metabolite and dietary exposure to AA. Wu and his team found that urinary N7- GAG is associated with solely AAMA, implying that AAMA may also serve as a surrogate biomarker for DNA damage due to AA exposure. The urinary N7-GAG of non-smokers and smokers is significantly associated with a very low level of dietary AA intake. Their results confirm that the N7-GAG found in the urine of smokers and non-smokers was a consequence of the exposure to AA, either through food consumption or tobacco smoke. Wu and his team discovered that the formation of N7-GAG in non-smokers with no occupational exposure history can most likely be attributed to the consumption of foods that have been processed at high temperatures. The mechanisms underlying the carcinogenicity of AA remain unclear, but the results demonstrating the association between urinary excretion of N7-GAG and recent exposure to AA provided new implication of AA’s mechanism in causing cancer (Potential genotoxicity via DNA alkylation). The newly developed analysis of urinary N7-GAG could considered to be a non-invasive method to measure the DNA alkylation by GA, and N7-GAG may be a very valuable biomarker to confirm the active metabolite of AA responsible for alkylating DNA, which results in mutagenicity in humans. In addition, it can serve as a chemical-specific and potential risk-associated biomarker in molecular epidemiology studies. Kuen-Yuh Wu*, Wei-Chung Shih, Yu-Syuan Luo (Department of Public Health & Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei 10055, Taiwan); Chih-Chun Jean Huang (Department of Food Science, National Pingtung University of Science and Technology, Neipu, Pingtung 91201, Taiwan); Chia-Fang Wu, Ming-Feng Chen, Chien-Ming Li, Saou-Hsing Liou (Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Zhunan Town, Miaoli County 35053, Taiwan); Wen-Sheng Chung (Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan); Su-Yin Chiang* (School of Chinese Medicine, China Medical University, Taichung 404, Taiwan) Reference Chih-Chun Jean Huang, Chia-Fang Wu, Wei-Chung Shih, Yu-Syuan Luo, Ming-Feng Chen, Chien-Ming Li, Saou-Hsing Liou, Wen-Sheng Chung, Su-Yin Chiang, and Kuen- Yuh Wu. (2015). Potential association of urinary N7-(2-carbamoyl-2- hydroxyethyl) guanine with dietary acrylamide intake of smokers and nonsmokers. Chemical Research in Toxicology 28, 43-50. DOI: 10.1021/ tx500265p. Professor Kuen-Yuh Wu Department of Public Health & Institute of Occupational Medicine and Industrial Hygiene kuenyuhwu@ntu.edu.tw