The roles of sulfotransferases in detoxication of many drugs, as well as in the metabolic activation of many chemical carcinogens, are increasingly recognized as highly significant. Sulfation is a key component in the metabolic formation of cytotoxic, mutagenic and/or carcinogenic molecules from xenobiotics that include benzylic alcohols derived from alkyl-substituted polycyclic aromatic hydrocarbons, hydroxylamine metabolites of aromatic amines and nitroaromatics, and allylic alcohols. The long-term goal of this research is to more fully understand and predict the roles that aryl and alcohol sulfotransferases play in the cytotoxic, mutagenic, and/or carcinogenic effects of xenobiotics that either possess or are biotransformed into metabolites containing benzylic alcohol, allylic alcohol, and N-hydroxy arylamine functional groups. The primary objective of the work proposed for the next project period is to address the gaps in our knowledge of the regulation of the catalytic function of these sulfotransferases by means other than gene expression and allelic variations. The proposed investigation is based on the central hypothesis that stereospecificity in recognition of substrates and inhibitors by aryl and alcohol sulfotransferases, the oxidative environment of these enzymes, and kinetic regulation by the co-substrate, PAPS, are critical components in the prediction of the rates of sulfation in drug metabolism and chemical carcinogenesis.
The specific aims of the research during the upcoming project period are to 1) continue elucidation of the stereoselectivity of interactions of allylic alpha-hydroxylated metabolites derived from Tamoxifen with rat STa and human SULT2A1 alcohol sulfotransferases and study the inhibition of these enzymes by Tamoxifen and its metabolites, 2) determine the role of the concentration of PAPS in the catalytic regulation of rat and human alcohol sulfotransferases, 3) determine the extent and significance of changes in kinetics resulting from disulfide bond formation in aryl and alcohol sulfotransferases, and 4) develop methods for design of isoform-specific inhibitors of aryl and alcohol sulfotransferases based on quantitative structure-activity relationships. The results of this research will provide significant new insight into the mechanisms for dynamic regulation of the catalytic function of aryl and alcohol sulfotransferases that are important to drug metabolism and chemical carcinogenesis as well as new methodology for the design of isoform-specific inhibitors of sulfotransferases. Thus, this project is highly relevant to public health due to its provision of increased understanding and prediction of the roles of sulfation both in drug metabolism and in the metabolism of xenobiotics to chemical carcinogens. Moreover, specific aim #1 has additional particular relevance to understanding and more accurately predicting the metabolism of Tamoxifen, a widely used antitumor agent and chemopreventive agent for estrogen-dependent breast cancer. ? ? ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA038683-22
Application #
7288763
Study Section
Xenobiotic and Nutrient Disposition and Action Study Section (XNDA)
Program Officer
Poland, Alan P
Project Start
1984-08-01
Project End
2011-07-31
Budget Start
2007-08-01
Budget End
2008-07-31
Support Year
22
Fiscal Year
2007
Total Cost
$221,064
Indirect Cost
Name
University of Iowa
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
062761671
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Ekuase, E J; van 't Erve, T J; Rahaman, A et al. (2016) Mechanistic insights into the specificity of human cytosolic sulfotransferase 2A1 (hSULT2A1) for hydroxylated polychlorinated biphenyls through the use of fluoro-tagged probes. Environ Sci Pollut Res Int 23:2119-27
Squirewell, Edwin J; Duffel, Michael W (2015) The effects of endoxifen and other major metabolites of tamoxifen on the sulfation of estradiol catalyzed by human cytosolic sulfotransferases hSULT1E1 and hSULT1A1*1. Drug Metab Dispos 43:843-50
Ekuase, Edugie J; Lehmler, Hans-Joachim; Robertson, Larry W et al. (2014) Binding interactions of hydroxylated polychlorinated biphenyls (OHPCBs) with human hydroxysteroid sulfotransferase hSULT2A1. Chem Biol Interact 212:56-64
Squirewell, Edwin J; Qin, Xiaoyan; Duffel, Michael W (2014) Endoxifen and other metabolites of tamoxifen inhibit human hydroxysteroid sulfotransferase 2A1 (hSULT2A1). Drug Metab Dispos 42:1843-50
Qin, Xiaoyan; Teesch, Lynn M; Duffel, Michael W (2013) Modification of the catalytic function of human hydroxysteroid sulfotransferase hSULT2A1 by formation of disulfide bonds. Drug Metab Dispos 41:1094-103
Dammanahalli, Jagadeesha K; Duffel, Michael W (2012) Oxidative modification of rat sulfotransferase 1A1 activity in hepatic tissue slices correlates with effects on the purified enzyme. Drug Metab Dispos 40:298-303
Liu, Yungang; Lehmler, Hans-Joachim; Robertson, Larry W et al. (2011) Physicochemical properties of hydroxylated polychlorinated biphenyls aid in predicting their interactions with rat sulfotransferase 1A1 (rSULT1A1). Chem Biol Interact 189:153-60
Ekuase, Edugie J; Liu, Yungang; Lehmler, Hans-Joachim et al. (2011) Structure-activity relationships for hydroxylated polychlorinated biphenyls as inhibitors of the sulfation of dehydroepiandrosterone catalyzed by human hydroxysteroid sulfotransferase SULT2A1. Chem Res Toxicol 24:1720-8
Gulcan, Hayrettin Ozan; Duffel, Michael W (2011) Substrate inhibition in human hydroxysteroid sulfotransferase SULT2A1: studies on the formation of catalytically non-productive enzyme complexes. Arch Biochem Biophys 507:232-40
Liu, Yungang; Smart, Jason T; Song, Yang et al. (2009) Structure-activity relationships for hydroxylated polychlorinated biphenyls as substrates and inhibitors of rat sulfotransferases and modification of these relationships by changes in thiol status. Drug Metab Dispos 37:1065-72

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