DNA adductomics of the urinary system

The goal of our research is to chemically characterize DNA adducts associated with specific human cancers. We will link this structural information to novel mutational patterns identified during this research. These melded data should facilitate significantly the identification of environmental, dietary and endogenous agents responsible for human cancers. The proposed research focuses on renal and urological cancers; specifically, clear-cell renal cell carcinomas, carcinomas of the upper urinary tract and bladder cancer. Additionally, we will attempt to detect and, if possible, quantify single or multiple DNA adducts found in exfoliated urinary cells as an initial step in developing a noninvasive biomarker for carcinogen screening. In this research, we utilize sensitive, mass spectrometry techniques to detect and quantify multiple DNA adducts in target tissues and urinary cells. For screening purposes, we will employ ultraperformance liquid chromatography/multistage scan mass spectrometry (UPLC/MSn), using a linear quadrupole ion trap mass spectrometer. The use of UPLC/MSn permits quantitation of known adducts and characterization of unknown adducts, the latter by acquiring MS3 scan stage product ion spectra. We have employed this approach successfully to identify single and multiple DNA adducts in human tissues, saliva, and exfoliated urinary cells. In Aim 1, we use data-dependent and independent scanning methods to optimize detection of DNA adducts derived from genotoxins found in tobacco smoke and in the diet; also from electrophiles that are produced endogenously by oxidative processes. In Aim 2, we employ targeted as well as data-dependent and independent “adductomics” approaches, using UPLC/MSn to screen DNA adducts formed in the kidney, upper urothelial tract, bladder, and cells in the urine of patients with target cancers. In Aim 3, we conduct deep sequencing of DNA isolated from tumor and non-tumor tissues to identify mutational patterns that may be linked to specific DNA adducts, chemical exposures or aberrant endogenous processes. Our research has significant implications for public health. DNA adduct and mutational data are of high translational impact and provide an understanding of exposures to hazardous chemicals that can initiate cancer in humans. By linking these methods, we create a molecular approach that provides clues to the identity of environmental, dietary and endogenous carcinogens and establishes biomarkers of exposure that can be used in epidemiologic studies to identify populations at risk. Once identified, pragmatic measures can be taken to reduce human exposure to these chemicals, by changes in life-style and/or diet, which are probably the most efficient means of chemoprevention.