Project Summary (2005-2010)

Hazardous waste sites contain complex mixtures of a wide variety of toxic chemicals. Unfortunately, development of rapid and inexpensive detection of specific chemicals or chemical classes in environmental and biological samples has been hampered by the lack of available specific bioassay/biomarker systems. Accordingly, the overall goals of this project are to develop and validate a series of mechanistically-based cell and in vitro bioassays/biomarkers that have application for chemical detection and screening. Since effective development and application of bioassays/biomarkers is greatly facilitated by an understanding of the specific response of a cell to a given toxicant or class of toxicants, each of the four proposed approaches exploit information derived from an analysis of the basic molecular mechanisms by which selected chemicals affect cellular receptors, signal transduction pathways and cellular/enzyme functions.

1. stably transfected cell lines are developed which respond to dioxin-like chemicals, steroid/thyroid hormones or hormone-like chemicals with the induction or inhibition of receptor dependent expression of firefly luciferase or green fluorescent protein reporter genes. Dr. Denison’s team also develops a novel portable in vitro AhR-based bioassay for detection of dioxin-like chemicals.
2. human keratinocytes is also used to examine genomic, proteomic and metabolomic effects following exposure to metals/metalloids and chemicals that produce oxidative stress to identify potential biomarkers that are specifically altered by these chemicals.
3. in vitro and cell- based bioassay systems are used to examine the influence of Superfund chemicals on regulatory lipids that control inflammation and to identify xenobiotics that alter expression and activity of soluble epoxide hydrolase.
4. develops and validates ryanodine receptor-based in vitro and intact cell bioassays to identify and characterize non-coplanar halogenated persistent organic pollutants that can affect calcium-signaling pathways.

In the final goal, these assay systems are integrated and optimized and then used in a series of validation studies for the detection and relative quantitation of toxic chemicals present in complex mixtures of chemicals extracted from a variety of matrices. Overall, these studies not only increase basic knowledge of the biological and toxicological effects of a variety of Superfund priority chemicals, but the resulting specific bioassays and biomarkers that are being developed provide rapid mechanistically-based screening systems for the detection of toxicants and toxicant exposure.