This research effort is designed to examine the extent, persistence and biological consequences of DNA damage, with emphasis on parallel exposures and events occurring in animal models and human subjects. Compounds of intensive investigation include the carcinogenic drugs 3- azido-3-deoxythymidine (AZT) and tamoxifen (TAM), and the environmentally-relevant carcinogenic polycyclic aromatic hydrocarbons (PAHs). The nuceloside analog drug, AZT, which incorporates into DNA causing arrest of the replicating DNA strand, is currently used to prevent fetal HIV-1 transmission in infected pregnant women. However, it is a moderately-strong transplacental carcinogen in mice, and becomes incorporated into the DNA of newborn mouse organs. AZT-DNA incorporation has also been observed in cord blood DNA of 15/22 human infants, and in organ DNA of fetal Erythrocebus patas and Macaca mulatta monkeys exposed transplacentally for either long (last 50% of gestation) or short (4 hr before birth) periods of time, respectively. Documentation of AZT incorporation into mitochondrial DNA (mtDNA) of fetal patas monkeys is consistent with the mtDNA depletion observed in cardiac and skeletal muscle, and abnormal mt morphology revealed by electron microscopy (EM). In the same organs, dose-related abnormalities in oxidative phosphorylation enzyme activities associated with transplacental AZT exposure include a severe depletion of Complex I and increases in Complexes II and IV. A second drug carcinogenic in rodents is tamoxifen (TAM), which is administered in the clinic to prevent breast cancer. Oral administration of TAM causes liver tumors and DNA adduct formation in rats, and increased incidence of endometrial cancers in women. However, TAM-DNA adduct formation in human tissues has been controversial and un-resolved due to lack of sufficiently specific and sensitive methods. We have elicited an antiserum against TAM-DNA, and established and validated a highly- sensitive immunoassay able to detect 3 TAM-DNA adducts in 109 nucleotides. The TAM-DNA antiserum will be used in quantitative and immunohistochemical assays to explore TAM-DNA adduct formation in human tissues. Molecular dosimetry studies of individuals in China exposed to high levels of PAHs are in progress. An immunohistochemical method to quantitate PAH-DNA adduct levels in human esophageal biopsies has been developed using the Chroma Vision ACIS. Microdensitometry of PAH-DNA nuclear signal (fast red color intensity) has been quantified in human keratinocytes exposed to different levels of benzo[a]pyrene (BP), and nuclear color intensity increase with BP dose gives a correlation coefficient of 0.99. Preliminary staining of human esophageal samples is positive and suggests that the method may be useful in correlating PAH-DNA levels with esophageal cancer risk. - AIDS, Chemical carcinogenesis, DNA adducts, ovarian cancer, breast cancer, - Human Subjects & Human Tissues, Fluids, Cells, etc.
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