The long-term goal of this project is to develop a high-throughput technology that can characterize covalent protein and DNA modifications ("adducts") induced by reactive carcinogens on a global basis with high sensitivity and specificity. Virtually all carcinogens, even the most inert, either contain an electrophilic center or undergo some level of oxidative metabolism to form reactive electrophiles. DNA and protein adducts are the products of the chemical reaction of such electrophiles with nucleophilic sites within these macromolecules. DNA adduction (including methylation and oxidative changes) has been widely implicated in mutation and carcinogenesis, while protein adducts (i.e., post-translational modifications) may have indirect roles in the mechanism of carcinogenesis if they involve DNA-related proteins or increase the rate of tumor promotion. In addition, such adducts are being explored as short- term, long-term, and/or cumulative markers of exposure to carcinogens. Current methods of adduct quantitation are expensive, highly chemical-specific, and labor-intensive. A technology for rapid and comprehensive profiling of macromolecular adduction in human subjects would be an important tool for carcinogen exposure and health risk assessment. This exploratory/developmental application proposes a proof-of-concept study to adapt three recently developed technologies, i.e., combinatorial chemical synthesis, antibody phage display, and microarray technology in a system to rapidly profile blood protein adducts of two important classes of carcinogens. Libraries of adducted peptides will be created to mimic structures formed in vivo in humans exposed to carcinogens. Adduct-specific scFv probes will be selected by screening with phage display libraries and validated with human blood specimens in an ELISA system. Results of ELISA-based adduct quantitation will be compared to those from conventional mass spectrometry-based analysis of blood protein adducts. If the proposed proof-of-concept studies are successful, expanded funding will be sought to develop a microarray-based global adduct detector for screening blood specimens from individual subjects. It is anticipated that the technology developed in this project will have wide applications for carcinogen exposure assessment, biomarker discovery, clinical diagnosis, and assessment of cancer treatment efficacies.
Many environmental carcinogens are able to chemically react with proteins and DNA in the body to form products called adducts. These reaction products can be critical to the occurrence of cancer, or, alternatively, they can provide information on a person's exposure to these carcinogens. We propose to develop a rapid, reliable system to detect and measure these adducts in human specimens on a global basis, a technology that would be an important tool for carcinogen exposure assessment, clinical diagnosis, and assessment of cancer treatment efficacies.