BIOMARKERS OF CARCINOGENESIS

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Carcinogenesis is known to involve multiple steps of somatic mutation. During the last two decades various biomarkers have been developed to detect early chromosomal and mutational effects of carcinogenic exposure in humans. Although these biomarkers have been shown to be associated with a wide range of carcinogenic exposures, they are not truly biomarkers of early effect as they are not on the causal pathway of environmentally-induced cancers. These biomarkers should be better predictors of increased cancer risk than those currently available. Specific chromosome rearrangements and altered gene methylation are known to be key factors in the development of leukemia, lymphoma, lung and bladder cancer. We plan to develop novel quantitative real time PCR methods for a number of leukemia/lymphoma-related translocations (e.g. 1 (12;21) and t(14;18)) and methylation-specific PCR methods that allow us to examine the methylation status of various cancer-related genes (e.g.p16/INK4a and p14/ARF. We will then make an initial test of the association of some of these markers with non-Hodgkins lymphoma and examine their prevalence in the general population, including newborns. There is currently considerable debate about the presence of translocations in human blood, especially in newborns. In addition, we will perform in vitro cell culture studies with these new markers to examine the nature of the chromosomal damage and aberrant gene methylation produced in critical target cells by the Superfund chemicals, arsenic and benzene. We also plan to use the real-time PCR methods to backtrack leukemia to birth in newborn blood samples from childhood leukemia cases collected under Project 2. This will determine if the translocations or inversions present in the blood of leukemia cases were present at birth and open up new avenues for potentially predicting childhood leukemia. Finally, we will apply the methylation specific-PCR methods to specific genes in leukemia marrow samples collected under Project 2 and in lung and bladder tumors from arsenic endemic areas collected under Project 3, to determine if chemical-specific gene methylation patterns exist in the tumors.