Molecular Epidemiology of Breast Cancer: Development and Validation of Acetylation Methods for Carcinogen-DNA Adduct Detection

Abstract : Molecular epidemiology can elucidate new breast cancer risk factors and gene-environment interactions relating to both hormonal and non-hormonal carcinogenic mechanisms. Corroborative epidemiological studies of intermediate biomarkers of carcinogenesis and laboratory studies demonstrating functional importance of the epidemiology findings are needed. The study of carcinogen-DNA adducts can provide corroborative evidence for the importance of genetic susceptibilities in breast cancer risk. We are establishing new assays for the detection of carcinogen-DNA adducts, use it for the first time in humans, and rigorously validate it to prove its utility for human breast tissue analysis in epidemlological studies, and determine adduct levels in relation to metabolizing gene polymorphisms. The originally proposed assay is novel because one uses a new chemical postlabeling method and quantitates adducts by accelerator mass spectroscopy (an ultrasensitive 14-C detection unit) . We are now also using an enzymatic postlabeling method that will still rely upon 14-C AMS detection, but is specific for 4-aminobiphenyl. We are also continuing to develop a capillary HPLC and laser-induced flourescence for polycyclic aromatic hydrocarbons. Once validated, we will learn the variability for DNA adduct levels in the population as it relates to age, gender, race, and smoking in breast tissues from 235 donors (200 women, 35 men). In order to understand the determinants of DNA adduct formation in the breast tissue, we also have been identifying cytochrome P450 immunostaining in the same tissues. Concurrently, we have been collecting and using cultured breast strains from normal donors to determine In vitro adduct formation levels and correlate these levels with p53 induction. Thus, this study will provide new information about genotype-phenotype relationships.