MOLECULAR DOSIMETRY OF PAH AND ESTROGEN ADDUCTS IN URINE

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We propose to develop monoclonal antibody-based procedures for molecular dosimetry of depurinating DNA adducts of benzo[alpha]pyrene (BP) and dibenzo[alpha,l]pyrene (DB[alpha,l]P), carcinogens viewed as indicators of exposure to polycyclic aromatic hydrocarbons (PAH) and risk of cancer, and catechol estrogens (CE), putative endogenous procarcinogens. Recent data support an essential contribution of depurinating adducts to cancer initiation by both PAH and CE. Since these adducts are frequently the predominant ones formed, are rapidly lost from the DNA and are excreted in urine, they are potentially useful biomarkers of chemical-specific DNA damage and risk for cancer. This project encompasses the production of monoclonal antibodies (MABs) specific for BP=6=C8Gua(a major depurinating adduct of BP; Aim #1), syn-DB[alpha,l]PDE-14-N7Ade and DB[alpha,l]P-10- N3Ade (major depurinating adducts of DB[alpha,l]P; Aim #2), and 4-OHE1- (1&2)}-N7Gua and 4-OHE2-(1&2)-N7Gua (predominant depurinating adducts of CE; Aim #3). The specific affinities of these MAbs will be determined by competitive enzyme-linked immunosorbent assay (ELISA). In the early stages of development of the proposed molecular dosimeters, MAbs of high specific affinity will be incorporated into competitive ELISAs and immunoaffinity HPLC (1A/HPLC) for quantitation of each adduct added to urine collected from normal rats and humans. Dose-response studies will compare urinary adducts, measured by competitive ELISA or IA/HPLC, with doses of PAH or CE given to rats. Transitional epidemiological studies will apply the MAb- based dosimeters to quantitation of BP adducts in the urine of smokers and nonsmokers, and DB[alpha,l]P adducts in the urine of individuals who are exposed to byproducts of smoky coal combustion and are at high risk for lung cancer. These studies will provide molecular dosimetric procedures needed for prospective epidemiological studies and determination of individual risk for both PAH- and CE-induced cancers.