Pulmonary Biomarkers Based on Alterations in Protein Expression Following Exposure to ArsenicEPA Grant Number: R832095
Title: Pulmonary Biomarkers Based on Alterations in Protein Expression Following Exposure to Arsenic
Investigators: Lantz, R. Clark , Boitano, Scott A. , Burgess, Jefferey L.
Institution: University of Arizona
EPA Project Officer: Hahn, Intaek
Project Period: January 8, 2005 through January 16, 2009
Project Amount: $731,453
RFA: Application of Biomarkers to Environmental Health and Risk Assessment (2004) RFA Text | Recipients Lists
Research Category: Health Effects , Hazardous Waste/Remediation , Human Health , Health
Exposure to arsenic (As) has been linked to lung cancer. Environmental exposure to these metals will result in multiple adverse effects, which can be characterized through evaluation of alterations in protein expression. We will evaluate such alterations as biomarkers of exposure and effect prior to the development of cancer. This study will use the technology of proteomics to evaluate and identify biomarkers of chronic environmental exposure to As by evaluating large numbers of proteins simultaneously. We will compare alterations in protein expression in exposed human populations in Arizona, human cell lines, and in vivo rodent studies. Patterns of alterations in protein expression, both common and unique to these different cell types, will be identified. These will be correlated with alterations in DNA oxidation in induced sputum from the lung, which we have recently found to be related to the levels of arsenic exposure.
We will determine the effects of arsenic exposure by first utilizing in vitro human lung cells. 16HBE4o- cells, a virally transformed human bronchial epithelial cell line, will be exposed to arsenic in vitro for 4 weeks. Levels of exposure will be control, 5 ppb, 10 ppb, 20 ppb, 50 ppb and 100 ppb As. Supernatant and cellular proteins will be collected and subjected to analysis and identification using 2D gel electrophoresis and mass spectrometry techniques. Arsenic-induced alterations in secreted or cellular proteins will be identified. The levels of protein expression will be validating using standard ELISA kits, when commercially available. Similar analyses will be carried out on mouse bronchoalveolar lavage fluid and cells following in vivo ingestion of arsenic. Male mice will be exposed to arsenic in their drinking water for 4 weeks. Concentrations will be the same as for the in vitro studies. Common changes in protein expression between these different assay systems will guide analysis of human samples. We currently have on hand thirty samples from control (As < 5 ppb in drinking water) and 20 ppb arsenic populations for analysis. DNA oxidation in sputum samples from the 20 ppb population is significantly higher than in the 5 ppb population. We will evaluate two additional human population groups based on their potential exposure (approximately 50 ppb and 100 ppb). Forty non-smoking subjects in each of the exposure groups (total n = 80) will be recruited for collection of fluid and cells through sputum induction as well as measurement of urine As. Supernatant and cellular proteins will be extracted and analyzed based on the proteins that were identified in the previous in vitro and animal experiments. Initial analysis will focus on alterations in proteins associated with cell cycle control, proliferation, inflammation and oxidative stress. Data from human, in vitro and animal studies will be correlated with the levels of As exposure and with the degree of DNA oxidation.
This study examines exposure indicators through cell lines, in vivo models and through epidemiological assessment of humans and human tissue for intermediate biological endpoints associated with cancer risk. Overall patterns of alterations in protein expression may vary among in-vitro, in vivo, and human studies. However, suites of proteins in specific pathways (e.g., apoptosis, cell-cycle control, etc.) may demonstrate similar patterns, thus providing us not only with biomarkers, but also with indicators as to the mechanism(s) of action of arsenic. These similarities and differences will help inform risk assessment by suggesting which mechanisms and biological endpoints in humans can be reasonably modeled using non-human studies.