Abstract 4619: DNA adductome analyses at multiple sites of human gastric mucosa, resected for gastric cancer
Authors: Kurabe Nobuya , Ohnishi Ippei , Suzuki Masako , Inoue Yusuke , Kahyo Tomoaki , Iwaizumi Moriya , Matsushima Yoshitaka , Totsuka Yukari , Nakagama Hitoshi , Kasami Masako , Ochiai Hideto , Matsumoto Keigo , Suzuki Shioto , Tanioka Fumihiko , Sugimura Haruhiko 
Published: August 2015

DNA adducts are recognized as an initiative step of mutagenesis, but the measurement of them is still a technical challenge. So-called adductome approach, based on LC-MS/MS, is a popular procedure to identify multiple DNA adducts in various tissues at a single experiments. Recently we reported 7 lipid peroxidation-induced DNA adducts in human gastric mucosa resected for gastric cancer in two countries for the first time, and showed the profile of these DNA adducts could indicate geo-pathological background of gastric mucosa (Matsuda 2013). Though DNA adductome approach posesses the high throghput potential in terms of finding numerous specis of DNA adducts having different molecular weights, there are still challenges to overcome. First of all, the numbers of the standards of DNA adducts molecules available are less than the species with identified molecular weight. This implies there are much more DNA modifications in human tissues than previously characterized. The other challaenge is that the absolute quantifications of these adducts requires isotopic standard chemicals. In this study, we strengthened DNA adductome method by including as many as known adducts in the assay system. Mass/Charge value and liquid chromatography retention time of known 254 DNA addcuts were collected and incoporated into LC-MS/MS machine (4000-QTRAP; Thermo). By this procedure we could measure the 254 DNA adducts at one time in MRM mode. Using this system, we measured 254 DNA adducts in the following human gastric mucosa. Written informed consents were obtained from the patients who took gastrectomy for gastric cancer. Under the hypothesis of field cancerization of gastric mucosa, in order to analyze the spatial influence of the exposure of the potential carcinogens toward cancer site, muocsal tissue at multiple sites with different distance to cancer, (10cm and more distant from the tumor site in the stomach to the site adjacent to the tumor) were taken. Three to 10 sites/case were investigated for DNA adducts measurements. Totally 11 cases and 77 sites are analyzed.

Considerable numbers of known DNA adducts were present in human gastric mucosa in different quantities. Among them, tobacco-related and lipid-peroxidation-induced DNA adducts were noted. We also did the same measurements in proximal, middle, and distal gastric mucosa from autospy cases without gastric cancer and compared them to those of the cancer cases. Among them, etheno-dA was able to be quantitatively measured using isotopic standard. The mean level of etheno dA in the gastric mucosa of autopsy cases without gastric cancer was 8.02/107 nucleotides, while that of gastric cancer patients mucosae was 4.80/107 nucleotides. These comprehensive identifications in adducts in human gastric mucosa will provide the basic information for dosimetry and risk assessment of environmental chemicals toward gastric cancer.

Citation Format: Nobuya Kurabe, Ippei Ohnishi, Masako Suzuki, Yusuke Inoue, Tomoaki Kahyo, Moriya Iwaizumi, Yoshitaka Matsushima, Yukari Totsuka, Hitoshi Nakagama, Masako Kasami, Hideto Ochiai, Keigo Matsumoto, Shioto Suzuki, Fumihiko Tanioka, Haruhiko Sugimura. DNA adductome analyses at multiple sites of human gastric mucosa, resected for gastric cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4619. doi:10.1158/1538-7445.AM2015-4619