Project Summary (2000-2006)

The goal of this project is to elucidate the mutagenic pathways involved in arsenite-treated cells. Although arsenic is a well-established human carcinogen and induces cancers of the skin, liver, bladder, and lung, the underlying mechanism(s) for this action is unknown. Using the human-hamster hybrid (AL) cells that are sensitive in detecting multilocus deletions, arsenic was shown to be mutagenic to endogenous genes in mammalian cells. Researchers are determining if reactive oxygen species, particularly hydroxyl radicals generated by arsenite, result in oxidative DNA damage and mutagenesis in AL cells. The induction of the oxidative DNA damage product, 8-OHdG, and the formation of hydroxyl radicals is being determined from arsenite-treated cultures using immunoperoxidase staining and the salicylate assay, respectively. Additionally, project investigators are determining the role of mitochondria in mediating the genotoxic response of arsenite. The AL cells contain only one copy of human chromosome 11 and mutations on marker genes located on this chromosome can be readily scored using an antibody complement lysis technique. Since the AL cells also contain the HPRT gene located on the hamster X chromosome, mutations induced by arsenic on an essential (-X) versus a non-essential chromosome (human chromosome 11) are providing useful information on the types and sizes of the induced molecular alterations.