ToxSci Advance Access originally published online on January 8, 2008
Toxicological Sciences 2008 102(2):319-327; doi:10.1093/toxsci/kfn003
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Positive Signaling Interactions between Arsenic and Ethanol for Angiogenic Gene Induction in Human Microvascular Endothelial Cells
Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania 15219
1 To whom correspondence should be addressed at Aaron Barchowsky, Ph.D., Department of Environmental and Occupational Health, Bridgeside Point, 100 Technology Drive, Rm 332, Pittsburgh, PA 15219. Fax: (412) 624-8864. E-mail: aab20{at}pitt.edu.
Received November 5, 2007; accepted December 31, 2007
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Abstract |
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Arsenic in the drinking water may promote vascular diseases in millions of people worldwide through unresolved mechanisms. In addition, little is known of the effects of coexposures to arsenic and other common vasculature toxicants, such as alcohol. To investigate signaling interactions between arsenic and alcohols, primary human microvascular endothelial (HMVEC) cells were exposed to noncytotoxic concentrations of arsenite (1–5µM) in the presence or absence of 0.1% ethanol (EtOH). Coexposure, but not exposure to either agent alone, rapidly increased active Fyn tyrosine kinase, tyrosine phosphorylation of a 109-kDa protein and serine phosphorylation of protein kinase C (PKC)
. The 109-kDa protein was identified as PYK2, a regulator of vascular integrin signaling and an upstream activator of PKC. Membrane localization of phospholipase C
1 was increased by coexposure within 15 min, but not by either agent alone. In contrast, both agents equally increased membrane localization of Rac1–GTPase. Coexposure, but not exposure to either agent alone, induced transcript levels for the angiogenic genes, vascular endothelial cell growth factor (Vegfa) and insulin-like growth factor-1 (Igf1). However, EtOH inhibited arsenic-induced, nuclear factor-
B–driven interleukin-8 and collagen-1 expression. Differential effects of selective PKC inhibitors on induced gene expression combined with a lack of interaction for induction of hemeoxygenase-1 further demonstrated that arsenic-responsive signaling pathways differ in sensitivity to EtOH interactions. Finally, coexposure enhanced endothelial tube formation in in vitro angiogenesis assays. These data indicate that complex interactions occur between arsenic and EtOH exposures that functionally affect endothelial signaling for gene induction and remodeling stimuli.
Key Words: arsenic; alcohol; endothelial; angiogenesis; cell signaling.