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Bellamri M, Xiao S, Murugan P, Weight CJ, Turesky RJ. Metabolic Activation of the Cooked Meat Carcinogen 2-Amino-1-Methyl-6-Phenylimidazo[4,5-b]Pyridine in Human Prostate. Toxicol Sci 2019; 163:543-556. [PMID: 29596660 DOI: 10.1093/toxsci/kfy060] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), an heterocyclic aromatic amine (HAA) formed in cooked meat, is a rodent and possible human prostate carcinogen. Recently, we identified DNA adducts of PhIP in the genome of prostate cancer patients, but adducts of 2-amino-3, 8-dimethylmidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-9 H-pyrido[2,3-b]indole (AαC), other prominent HAAs formed in cooked meats, were not detected. We have investigated the bioactivation of HAAs by Phase I and II enzymes in the human prostate (LNCaP) cell line using cytotoxicity and DNA adducts as endpoints. PhIP, MeIQx, and 2-amino-3-methylimidazo[4,5-f]quinoline, another HAA found in cooked meats, were poorly bioactivated and not toxic. The synthetic genotoxic N-hydroxylated-HAAs were also assayed in LNCaP cells with Phase II enzyme inhibitors. Notably, 2-hydroxy-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (HONH-PhIP), but not other HONH-HAAs, induced cytotoxicity. Moreover, PhIP-DNA adduct formation was 20-fold greater than adducts formed with other HONH-HAAs. Pretreatment of LNCaP cells with mefenamic acid, a specific inhibitor of sulfotransferase (SULT1A1), decreased PhIP-DNA adducts by 25%, whereas (Z)-5-(2'-hydroxybenzylidene)-2-thioxothiazolidin-4-one and pentachlorophenol, inhibitors of SULTs and N-acetyltransferases (NATs), decreased the PhIP-DNA adduct levels by 75%. NATs in cytosolic fractions of LNCaP cells and human prostate catalyzed DNA binding of HONH-PhIP by up to 100-fold greater levels than for SULT and kinase activities. Recombinant NAT2 is catalytically superior to recombinant NAT1 in the bioactivation of HONH-PhIP; however, the extremely low levels of NAT2 activity in prostate suggest that NAT1 may be the major isoform involved in PhIP-DNA damage. Thus, the high susceptibility of LNCaP cells recapitulates the DNA-damaging effect of HONH-PhIP in rodent and human prostate.
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Affiliation(s)
- Medjda Bellamri
- Masonic Cancer Center and Department of Medicinal Chemistry, Cancer and Cardiovascular Research Building
| | - Shun Xiao
- Masonic Cancer Center and Department of Medicinal Chemistry, Cancer and Cardiovascular Research Building
| | | | | | - Robert J Turesky
- Masonic Cancer Center and Department of Medicinal Chemistry, Cancer and Cardiovascular Research Building
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Rasool MI, Bairam AF, Gohal SA, El Daibani AA, Alherz FA, Abunnaja MS, Alatwi ES, Kurogi K, Liu MC. Effects of the human SULT1A1 polymorphisms on the sulfation of acetaminophen,O-desmethylnaproxen, and tapentadol. Pharmacol Rep 2018; 71:257-265. [PMID: 30822619 DOI: 10.1016/j.pharep.2018.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 11/19/2018] [Accepted: 12/07/2018] [Indexed: 12/25/2022]
Abstract
BACKGROUND Non-opioid and opioid analgesics, as over-the-counter or prescribed medications, are widely used for the management of a diverse array of pathophysiological conditions. Previous studies have demonstrated the involvement of human cytosolic sulfotransferase (SULT) SULT1A1 in the sulfation of acetaminophen, O-desmethylnaproxen (O-DMN), and tapentadol. The current study was designed to investigate the impact of single nucleotide polymorphisms (SNPs) of the human SULT1A1 gene on the sulfation of these analgesic compounds by SULT1A1 allozymes. METHODS Human SULT1A1 genotypes were identified by database search. cDNAs corresponding to nine SULT1A1 nonsynonymous missense coding SNPs (cSNPs) were generated by site-directed mutagenesis. Recombinant wild-type and SULT1A1 allozymes were bacterially expressed and affinity-purified. Purified SULT1A1 allozymes were analyzed for sulfation activity using an established assay procedure. RESULTS Compared with the wild-type enzyme, SULT1A1 allozymes were shown to display differential sulfating activities toward three analgesic compounds, acetaminophen, O-desmethylnaproxen (O-DMN), and tapentadol, as well as the prototype substrate 4NP. CONCLUSION Results obtained indicated clearly the impact of genetic polymorphisms on the drug-sulfation activity of SULT1A1 allozymes. Such information may contribute to a better understanding about the differential metabolism of acetaminophen, O-DMN, and tapentadol in individuals with different SULT1A1 genotypes.
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Affiliation(s)
- Mohammed I Rasool
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA; Department of Pharmacology, College of Pharmacy, University of Karbala, Karbala, Iraq
| | - Ahsan F Bairam
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA; Department of Pharmacology, College of Pharmacy, University of Kufa, Najaf, Iraq
| | - Saud A Gohal
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Amal A El Daibani
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Fatemah A Alherz
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Maryam S Abunnaja
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Eid S Alatwi
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Katsuhisa Kurogi
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA; Biochemistry and Applied Biosciences, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Ming-Cheh Liu
- Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA.
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Asai Y, Sakakibara Y, Kondo M, Nadai M, Katoh M. Expression and activities of sulfotransferase in rat brain. Xenobiotica 2018; 49:270-275. [DOI: 10.1080/00498254.2018.1440656] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Yuki Asai
- Department of Pharmaceutics, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Yukiko Sakakibara
- Department of Pharmaceutics, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Miyabi Kondo
- Department of Pharmaceutics, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Masayuki Nadai
- Department of Pharmaceutics, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Miki Katoh
- Department of Pharmaceutics, Faculty of Pharmacy, Meijo University, Nagoya, Japan
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Yalcin EB, Kulkarni SR, Slitt AL, King R. Bisphenol A sulfonation is impaired in metabolic and liver disease. Toxicol Appl Pharmacol 2016; 292:75-84. [PMID: 26712468 PMCID: PMC4724572 DOI: 10.1016/j.taap.2015.12.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 12/11/2015] [Accepted: 12/16/2015] [Indexed: 01/22/2023]
Abstract
BACKGROUND Bisphenol A (BPA) is a widely used industrial chemical and suspected endocrine disruptor to which humans are ubiquitously exposed. The liver metabolizes and facilitates BPA excretion through glucuronidation and sulfonation. The sulfotransferase enzymes contributing to BPA sulfonation (detected in human and rodents) is poorly understood. OBJECTIVES To determine the impact of metabolic and liver disease on BPA sulfonation in human and mouse livers. METHODS The capacity for BPA sulfonation was determined in human liver samples that were categorized into different stages of metabolic and liver disease (including obesity, diabetes, steatosis, and cirrhosis) and in livers from ob/ob mice. RESULTS In human liver tissues, BPA sulfonation was substantially lower in livers from subjects with steatosis (23%), diabetes cirrhosis (16%), and cirrhosis (18%), relative to healthy individuals with non-fatty livers (100%). In livers of obese mice (ob/ob), BPA sulfonation was lower (23%) than in livers from lean wild-type controls (100%). In addition to BPA sulfonation activity, Sult1a1 protein expression decreased by 97% in obese mouse livers. CONCLUSION Taken together these findings establish a profoundly reduced capacity of BPA elimination via sulfonation in obese or diabetic individuals and in those with fatty or cirrhotic livers versus individuals with healthy livers.
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Affiliation(s)
- Emine B Yalcin
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, United States
| | - Supriya R Kulkarni
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, United States
| | - Angela L Slitt
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, United States.
| | - Roberta King
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, United States.
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Rougée LRA, Richmond RH, Collier AC. Molecular reproductive characteristics of the reef coral Pocillopora damicornis. Comp Biochem Physiol A Mol Integr Physiol 2015; 189:38-44. [PMID: 26231839 DOI: 10.1016/j.cbpa.2015.07.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 07/11/2015] [Accepted: 07/21/2015] [Indexed: 11/19/2022]
Abstract
Coral reefs are an indispensible worldwide resource, accounting for billions of dollars in cultural, economic, and ecological services. An understanding of coral reproduction is essential to determining the effects of environmental stressors on coral reef ecosystems and their persistence into the future. Here, we describe the presence of and changes in steroidal hormones along with associated steroidogenic and steroid removal enzymes during the reproductive cycle of the brooding, pan-Pacific, hermaphroditic coral, Pocillopora damicornis. Detectable levels of 17β-estradiol, estrone, progesterone and testosterone were consistently detected over two consecutive lunar reproductive cycles in coral tissue. Intra-colony variation in steroid hormone levels ranged between 1.5- and 2.2-fold and were not statistically different. Activities of the steroidogenic enzymes 3β-hydroxysteroid dehydrogenase and cytochrome P450 (CYP) 17 dehydrogenase were detectable and did not fluctuate over the reproductive cycle. Aromatase-like activity was detected during the lunar reproductive cycle with no significant fluctuations. Activities of regeneration enzymes did not fluctuate over the lunar cycle; however, activity of the clearance enzyme UDP-glucuronosyl transferases increased significantly (ANOVA, post hoc p<0.01) during the two weeks before and after peak larval release (planulation), suggesting that the activity of this enzyme family may be linked to the reproductive state of the coral. Sulfotransferase enzymes could not be detected. Our findings provide the first data defining normal physiological and lunar/reproductive variability in steroidal enzymes in a coral species with respect to their potential role in coral reproduction.
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Affiliation(s)
- Luc R A Rougée
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii at Manoa, 41 Ahui Street, Honolulu, HI 96813, USA; Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, Honolulu, HI 96813, USA
| | - Robert H Richmond
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii at Manoa, 41 Ahui Street, Honolulu, HI 96813, USA
| | - Abby C Collier
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street, Honolulu, HI 96813, USA.
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Lyu C, Zhou W, Zhang Y, Zhang S, Kou F, Wei H, Zhang N, Zuo Z. Identification and characterization of in vitro and in vivo metabolites of steroidal alkaloid veratramine. Biopharm Drug Dispos 2015; 36:308-24. [PMID: 25765359 DOI: 10.1002/bdd.1942] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Revised: 02/11/2015] [Accepted: 02/25/2015] [Indexed: 12/22/2022]
Abstract
Veratramine, a steroidal alkaloid originating from Veratrum nigrum L., has demonstrated distinct anti-tumor and anti-hypertension effects, however, its metabolism has rarely been explored. The objective of the current study was to provide a comprehensive investigation of its metabolic pathways. The in vitro metabolic profiles of veratramine were evaluated by incubating it with liver microsomes and cytosols. The in vivo metabolic profiles in plasma, bile, urine and feces were monitored by UPLC-MS/MS after oral (20 mg/kg) and i.v. (50 µg/kg) administration in rats. Meanwhile, related P450s inhibitors and recombinant P450s and SULTs were used to identify the isozymes responsible for its metabolism. Eleven metabolites of veratramine, including seven hydroxylated, two sulfated and two glucuronidated metabolites, were characterized. Unlike most alkaloids, the major reactive sites of veratramine were on ring A and B instead of on the amine moiety. CYP2D6 was the major isozyme mediating hydroxylation, and substrate inhibition was observed with a Vmax , Ki and Clint of 2.05 ± 0.53 nmol/min/mg, 33.08 ± 10.13 µ m and 13.58 ± 1.27 µL/min/mg. SULT2A1, with Km , Vmax and Clint values of 19.37 ± 0.87 µ m, 1.51 ± 0.02 nmol/min/mg and 78.19 ± 8.57 µL/min/mg, was identified as the major isozyme contributing to its sulfation. In conclusion, CYP2D6 and SULT2A1 mediating hydroxylation and sulfation were identified as the major biotransformation for veratramine.
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Affiliation(s)
- Chunming Lyu
- Technology Laboratory Center, Shanghai University of Traditional Chinese Medicine, Shanghai, PR China.,School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
| | - Wenbin Zhou
- Center for Chinese Medical Therapy and Systems Biology, Shanghai University of Traditional Chinese Medicine, Shanghai, PR China
| | - Yufeng Zhang
- School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
| | - Shen Zhang
- Department of Rehabilitation, Changzheng Hospital Affiliated to Second Military Medicine University, Shanghai, 200003, PR China
| | - Fang Kou
- Center for Chinese Medical Therapy and Systems Biology, Shanghai University of Traditional Chinese Medicine, Shanghai, PR China
| | - Hai Wei
- Center for Chinese Medical Therapy and Systems Biology, Shanghai University of Traditional Chinese Medicine, Shanghai, PR China
| | - Ning Zhang
- Technology Laboratory Center, Shanghai University of Traditional Chinese Medicine, Shanghai, PR China
| | - Zhong Zuo
- School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
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Tian X, Huo X, Dong P, Wu B, Wang X, Wang C, Liu K, Ma X. Sulfation of melatonin: Enzymatic characterization, differences of organs, species and genders, and bioactivity variation. Biochem Pharmacol 2015; 94:282-96. [DOI: 10.1016/j.bcp.2015.02.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 02/16/2015] [Accepted: 02/16/2015] [Indexed: 12/20/2022]
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Yalcin EB, More V, Neira KL, Lu ZJ, Cherrington NJ, Slitt AL, King RS. Downregulation of sulfotransferase expression and activity in diseased human livers. Drug Metab Dispos 2013; 41:1642-50. [PMID: 23775849 DOI: 10.1124/dmd.113.050930] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Sulfotransferase (SULT) function has been well studied in healthy human subjects by quantifying mRNA and protein expression and determining enzyme activity with probe substrates. However, it is not well known if sulfotransferase activity changes in metabolic and liver disease, such as diabetes, steatosis, or cirrhosis. Sulfotransferases have significant roles in the regulation of hormones and excretion of xenobiotics. In the present study of normal subjects with nonfatty livers and patients with steatosis, diabetic cirrhosis, and alcoholic cirrhosis, we sought to determine SULT1A1, SULT2A1, SULT1E1, and SULT1A3 activity and mRNA and protein expression in human liver tissue. In general, sulfotransferase activity decreased significantly with severity of liver disease from steatosis to cirrhosis. Specifically, SULT1A1 and SULT1A3 activities were lower in disease states relative to nonfatty tissues. Alcoholic cirrhotic tissues further contained lower SULT1A1 and 1A3 activities than those affected by either of the two other disease states. SULT2A1, on the other hand, was only reduced in alcoholic cirrhotic tissues. SULT1E1 was reduced both in diabetic cirrhosis and in alcoholic cirrhosis tissues, relative to nonfatty liver tissues. In conclusion, the reduced levels of sulfotransferase expression and activity in diseased versus nondiseased liver tissue may alter the metabolism and disposition of xenobiotics and affect homeostasis of endobiotic sulfotransferase substrates.
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Affiliation(s)
- Emine B Yalcin
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, USA
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Sugawara A, Sato B, Bal E, Collier AC, Ward MA. Blastomere removal from cleavage-stage mouse embryos alters steroid metabolism during pregnancy. Biol Reprod 2012; 87:4, 1-9. [PMID: 22517623 DOI: 10.1095/biolreprod.111.097444] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Preimplantation genetic diagnosis (PGD) is a genetic screening of embryos conceived with assisted reproduction technologies (ART). A single blastomere from an early-stage embryo is removed and molecular analyses follow to identify embryos carrying genetic defects. PGD is considered highly successful for detecting genetic anomalies, but the effects of blastomere biopsy on fetal development are understudied. We aimed to determine whether single blastomere removal affects steroid homeostasis in the maternal-placental-fetal unit during mouse pregnancy. Embryos generated by in vitro fertilization (IVF) were biopsied at the four-cell stage, cultured to morula/early blastocyst, and transplanted into the oviducts of surrogate mothers. Nonbiopsied embryos from the same IVF cohorts served as controls. Cesarean section was performed at term, and maternal and fetal tissues were collected. Embryo biopsy affected the levels of steroids (estradiol, estrone, and progesterone) in fetal and placental compartments but not in maternal tissues. Steroidogenic enzyme activities (3beta-hydroxysteroid dehydrogenase, cytochrome P450 17alpha-hydroxylase, and cytochrome P450 19) were unaffected but decreased activities of steroid clearance enzymes (uridine diphosphate-glucuronosyltransferase and sulfotransferase) were observed in placentas and fetal livers. Although maternal body, ovarian, and placental weights did not differ, the weights of fetuses derived from biopsied embryos were lower than those of their nonbiopsied counterparts. The data demonstrate that blastomere biopsy deregulates steroid metabolism during pregnancy. This may have profound effects on several aspects of fetal development, of which low birth weight is only one. If a similar phenomenon occurs in humans, it may explain low birth weights associated with PGD/ART and provide a plausible target for improving PGD outcomes.
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Affiliation(s)
- Atsushi Sugawara
- Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii 96822, USA
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Cronin-Fenton DP, Lash TL. Clinical epidemiology and pharmacology of CYP2D6 inhibition related to breast cancer outcomes. Expert Rev Clin Pharmacol 2011; 4:363-77. [PMID: 21709817 PMCID: PMC3119576 DOI: 10.1586/ecp.11.18] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Adjuvant tamoxifen therapy of breast cancer patients with estrogen receptor-positive tumors reduces the rate of breast cancer recurrence by approximately a half. Tamoxifen is metabolized by several polymorphic enzymes, including cytochrome P450 2D6 (CYP2D6), to more active metabolites. We have reviewed the clinical pharmacology of tamoxifen and evaluated the evidence from clinical epidemiology studies regarding the association between CYP2D6 inhibition and tamoxifen effectiveness. We conclude that the impact of CYP2D6 inhibition on tamoxifen effectiveness is likely to be null or small, at least in the populations studied so far. Understanding the effect of variations in tamoxifen metabolism on breast cancer outcomes, if any, will likely require a broader perspective, including examination of the complete metabolic pathway and subgroups of patients with other markers of potentially poor tamoxifen response.
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Affiliation(s)
- Deirdre P Cronin-Fenton
- Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Alle 43–45, 8200 Aarhus C., Denmark.
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Ginsberg G, Guyton K, Johns D, Schimek J, Angle K, Sonawane B. Genetic polymorphism in metabolism and host defense enzymes: implications for human health risk assessment. Crit Rev Toxicol 2011; 40:575-619. [PMID: 20662711 DOI: 10.3109/10408441003742895] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Genetic polymorphisms in xenobiotic metabolizing enzymes can have profound influence on enzyme function, with implications for chemical clearance and internal dose. The effects of polymorphisms have been evaluated for certain therapeutic drugs but there has been relatively little investigation with environmental toxicants. Polymorphisms can also affect the function of host defense mechanisms and thus modify the pharmacodynamic response. This review and analysis explores the feasibility of using polymorphism data in human health risk assessment for four enzymes, two involved in conjugation (uridine diphosphoglucuronosyltransferases [UGTs], sulfotransferases [SULTs]), and two involved in detoxification (microsomal epoxide hydrolase [EPHX1], NADPH quinone oxidoreductase I [NQO1]). This set of evaluations complements our previous analyses with oxidative and conjugating enzymes. Of the numerous UGT and SULT enzymes, the greatest likelihood for polymorphism effect on conjugation function are for SULT1A1 (*2 polymorphism), UGT1A1 (*6, *7, *28 polymorphisms), UGT1A7 (*3 polymorphism), UGT2B15 (*2 polymorphism), and UGT2B17 (null polymorphism). The null polymorphism in NQO1 has the potential to impair host defense. These highlighted polymorphisms are of sufficient frequency to be prioritized for consideration in chemical risk assessments. In contrast, SNPs in EPHX1 are not sufficiently influential or defined for inclusion in risk models. The current analysis is an important first step in bringing the highlighted polymorphisms into a physiologically based pharmacokinetic (PBPK) modeling framework.
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Affiliation(s)
- Gary Ginsberg
- Connecticut Department of Public Health, Hartford, Connecticut 06106, USA.
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Koide CL, Collier AC, Berry MJ, Panee J. The effect of bamboo extract on hepatic biotransforming enzymes--findings from an obese-diabetic mouse model. JOURNAL OF ETHNOPHARMACOLOGY 2011; 133:37-45. [PMID: 20832461 PMCID: PMC3471658 DOI: 10.1016/j.jep.2010.08.062] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 08/26/2010] [Accepted: 08/31/2010] [Indexed: 05/23/2023]
Abstract
AIM OF THE STUDY Bamboo leaves are used as a component in traditional Chinese medicine for the anti-inflammatory function. Our previous studies have demonstrated that an ethanol/water extract from Phyllostachys edulis ameliorated obesity-associated chronic systemic inflammation in mice, and therefore relieving the symptoms of type 2 diabetes. The aim of this project was to further investigate the effects of this bamboo extract on hepatic biotransformation enzymes in both lean and obese mice, as an initial step in the toxicological evaluation of using this traditional medicine in obese/diabetic population. MATERIALS AND METHODS Male C57BL/6J mice were randomized to 4 groups and fed standard (10% kcal from fat) diet with or without bamboo extract supplementation at a dose of 10 gram per kilogram diet (n=10 and n=9, respectively), or high fat (45% kcal from fat) diet with or without bamboo extract (n=8 and N=7, respectively). The dietary treatment lasted for 6 months. Subsequently, the activities and expression of the major Phase I and II hepatic biotransformation enzymes were assessed in subcellular fractions from murine livers. RESULTS Three groups of mice, lean bamboo extract-supplemented, obese/diabetic, and bamboo extract-supplemented obese/diabetic, showed greater activities of cytochromes P450 1a2 and 3a11 compared to control but no changes in the expression level of these proteins. For Phase II enzymes, bamboo extract supplementation in lean mice caused decreased glutathione-S-transferase activity (-12%) and greater uridine diphosphate glucuronosyltransferase activity (+46%), but had no effect on sulfotransferase activity. Conversely, the obese/diabetic condition itself increased glutathione-S-transferase and uridine diphosphate glucuronosyltransferase activities, but decreased total sulfotransferase activity and sulfotransferase 2a1 expression. CONCLUSIONS Bamboo extract and obesity/diabetes show significant independent effects on hepatic biotransformation as well as interaction effects in mice. These changes may alter the clearance of endo- and xenobiotics, including bamboo extract itself, hence this effect should be carefully considered in the medicinal application of bamboo extract as it has potential to alter its own metabolism and that of other medications concurrently administered to obese diabetic patients.
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Affiliation(s)
- Cheryl L.K. Koide
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street BSB 222, Honolulu, HI 96813, United States
| | - Abby C. Collier
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street BSB 222, Honolulu, HI 96813, United States
| | - Marla J. Berry
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street BSB 222, Honolulu, HI 96813, United States
| | - Jun Panee
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street BSB 222, Honolulu, HI 96813, United States
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Riches Z, Stanley EL, Bloomer JC, Coughtrie MWH. Quantitative evaluation of the expression and activity of five major sulfotransferases (SULTs) in human tissues: the SULT "pie". Drug Metab Dispos 2009; 37:2255-61. [PMID: 19679676 DOI: 10.1124/dmd.109.028399] [Citation(s) in RCA: 274] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Expression levels of the major human sulfotransferases (SULTs) involved in xenobiotic detoxification in a range of human tissues (i.e., SULT "pies") are not available in a form allowing comparison between tissues and individuals. Here we have determined, by quantitative immunoblotting, expression levels for the five principal human SULTs-SULT1A1, SULT1A3/4, SULT1B1, SULT1E1, and SULT2A1-and determined the kinetic properties toward probe substrates, where available, for these enzymes in cytosol samples from a bank of adult human liver, small intestine, kidney, and lung. We produced new isoform-selective antibodies against SULT1B1 and SULT2A1, which were used alongside antibodies against SULT1A3 and SULT1A1 previously produced in our laboratory or available commercially (SULT1E1). Expression levels were derived using purified recombinant enzymes to construct standard curves for each individual isoform and immunoblot. Substantial intertissue and interindividual differences in expression were observed. SULT1A1 was the major enzyme (>50% of total, range 420-4900 ng/mg cytosol protein) in the liver, followed by SULT2A1, SULT1B1, and SULT1E1. SULT1A3 was completely absent from this tissue. In contrast, the small intestine contained the largest overall amount of SULT of any of the tissues, with SULT1B1 the major enzyme (36%), closely followed by SULT1A3 (31%), and SULT1A1, SULT1E1, and SULT2A1 more minor forms (19, 8, and 6% of total, respectively). The kidney and lung contained low levels of SULT. We provide a unique data set that will add value to the study of the role and contribution of sulfation to drug and xenobiotic metabolism in humans.
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Affiliation(s)
- Zoe Riches
- Division of Medical Sciences, Centre for Oncology and Molecular Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, United Kingdom
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Collier AC, Miyagi SJ, Yamauchi Y, Ward MA. Assisted reproduction technologies impair placental steroid metabolism. J Steroid Biochem Mol Biol 2009; 116:21-8. [PMID: 19406239 PMCID: PMC2702461 DOI: 10.1016/j.jsbmb.2009.04.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 03/28/2009] [Accepted: 04/20/2009] [Indexed: 11/28/2022]
Abstract
The placenta plays a vital role in pregnancy by facilitating steroid passage from maternal to fetal circulation and/or direct production of hormones. Using a murine model, we demonstrated the differences in placental steroid metabolism between pregnancies conceived naturally and with assisted reproduction technologies (ART): in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). While the ovarian steroid production was similar (estrone, 17beta-estradiol) or higher (estriol) in ART pregnancies compared to mating, the levels of placental estriol were significantly lower in ART group. Placentas from ART had significantly higher activities of the steroid metabolizing enzymes UDP-glucuronosyltransferase (UGT) and sulfotransferase (SULT), which in ICSI were also coupled with decreased activity of the steroid regenerating enzymes beta-glucuronidase (beta-G) and aryl sulfatase (AS). Levels of steroid metabolites androstane-3alpha-17beta-diol glucuronide and dehydroepiandrosterone sulfate were higher in fetal compared to maternal blood in ART, but not in mating. This study demonstrates that in murine ART pregnancies, higher metabolism and clearance of steroids by the placenta may seriously affect the passage of essential hormones to the fetus. If a similar phenomenon exists in humans, this could provide a plausible explanation for obstetric and neonatal complications associated with ART, including the higher incidence of low birth weight babies.
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Affiliation(s)
- Abby C. Collier
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo St, Honolulu, Hawaii, 96822, USA
| | - Shogo J. Miyagi
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo St, Honolulu, Hawaii, 96822, USA
| | - Yasuhiro Yamauchi
- Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii, 1960 East-West Rd, Honolulu, Hawaii, 96822, USA
| | - Monika A. Ward
- Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii, 1960 East-West Rd, Honolulu, Hawaii, 96822, USA
- Correspondence: Monika A Ward, Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii, 1960 East-West Rd, Honolulu, HI, 96822. Phone: 808-956-0779, Fax: 808-956-7316, E-mail:
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Mitra P, Audus KL. Expression and functional activities of selected sulfotransferase isoforms in BeWo cells and primary cytotrophoblast cells. Biochem Pharmacol 2009; 78:1475-82. [PMID: 19646966 DOI: 10.1016/j.bcp.2009.07.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 07/22/2009] [Accepted: 07/22/2009] [Indexed: 12/11/2022]
Abstract
Several cytosolic sulfotransferase enzyme isoforms are functional in placenta but there is limited information available on the utility of cultured trophoblast cells for studying sulfation. The trophoblast cell layer constitutes the rate-determining barrier for trans-placental transfer. The objective of this work was to examine the mRNA expression and enzyme activities of four sulfotransferase isoforms reported to be functional in human placenta (SULT1A1, SULT1A3, SULT1E1, and SULT2A1) in primary cytotrophoblast cells and the trophoblast-like BeWo cell line. Reverse transcription polymerase chain reaction (RT-PCR) was performed to determine mRNA expression. Enzyme activities were assessed using the following substrates: 4-nitrophenol for SULT1A1, dopamine for SULT1A3, 17beta-estradiol for SULT1E1, and dehydroepiandrosterone for SULT2A1. For 4-nitrophenol and dopamine sulfation, apparent K(m) values, response to inhibitors (2,6-dichloro-4-nitrophenol and sodium chloride), and thermal stability profiles indicated that 4-nitrophenol and dopamine sulfation in BeWo cells were being mediated by SULT1A1 and SULT1A3, respectively. SULT1A1 and SULT1A3 were also functional in the cytotrophoblast cells. Both at the protein and at the mRNA levels, SULT1A1 was more abundant in BeWo cells in comparison to the primary cytotrophoblast cells. SULT1E1 and SULT2A1 mRNA were not detected in the cytotrophoblasts. SULT1E1 mRNA was weakly expressed in BeWo but there was negligible functional activity. Although SULT2A1 mRNA was abundantly expressed in BeWo, Western blot and enzyme activities revealed that the protein is not expressed in BeWo cells. The results suggest that the BeWo cells and the cytotrophoblast cells can be used to examine the roles of SULT1A1 and SULT1A3 in placental metabolism.
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Affiliation(s)
- Pallabi Mitra
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Kansas, Lawrence, KS 66047, USA
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16
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Wang L, Raghavan N, He K, Luettgen JM, Humphreys WG, Knabb RM, Pinto DJ, Zhang D. Sulfation of O-Demethyl Apixaban: Enzyme Identification and Species Comparison. Drug Metab Dispos 2009; 37:802-8. [DOI: 10.1124/dmd.108.025593] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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17
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Lin Y, Collier AC, Liu W, Berry MJ, Panee J. The inhibitory effect of bamboo extract on the development of 7,12-dimethylbenz[a]anthracene (DMBA)-induced breast cancer. Phytother Res 2008; 22:1440-5. [PMID: 18972584 DOI: 10.1002/ptr.2439] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The incidence of breast cancer among women is high and increasing. This study investigated the inhibitory effect of an extract from bamboo Phyllostachys edulis on the development of 7,12-dimethylbenz[a]anthracene (DMBA)-induced breast cancer in female Sprague-Dawley rats. The rats were fed with bamboo extract (BEX) supplemented diet or control diet, and treated with DMBA after 3 weeks of the dietary regime. The incidence of mammary tumors was monitored by palpation for the next 11 weeks. At the end of the experiment, blood samples were collected for total antioxidant capacities (TAC) assay and liver samples for phase II enzyme activity assays. The TAC values, total contents of phenolics and flavonoids of BEX were also measured. The results showed that BEX delayed the onset of mammary tumor by 1 week, decreased the tumor incidence by 44% and tumor multiplicity by 67%, and increased the total sulfotransferases (SULT) activity by 63%. BEX showed high levels of TAC, total phenolic and total flavonoids. However, the serum TAC values were not affected by BEX supplementation. In summary, the results indicate that BEX possesses a potent anti-breast cancer effect, and the upregulation of SULT activity, therefore estrogen metabolism may be the underlying mechanism.
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Affiliation(s)
- Yanling Lin
- Department of Cell and Molecular Biology, John A Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street BSB 222, Honolulu, HI 96813, USA
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18
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Metabolism of resveratrol in breast cancer cell lines: impact of sulfotransferase 1A1 expression on cell growth inhibition. Cancer Lett 2007; 261:172-82. [PMID: 18082939 DOI: 10.1016/j.canlet.2007.11.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 11/08/2007] [Accepted: 11/09/2007] [Indexed: 11/22/2022]
Abstract
Resveratrol is a polyphenolic compound present in grapes and wine with anticancer activities that undergoes pronounced metabolism in humans. In order to determine whether metabolism of resveratrol also occurs in tumor cells and whether biotransformation has any impact on cytotoxicity, metabolism experiments were conducted with hormone-dependent ZR-75-1 and hormone-independent MB-MDA-231 human breast cancer cells. Along with resveratrol, it was possible to identify one metabolite, namely, resveratrol-3-O-sulfate in both cell lines. Its concentration in the cytoplasm and culture medium was 5.4- to 9-fold higher in ZR-75-1 cells than in MDA-MB-231 cells, concomitant with a 3.1-fold higher IC(50) value in the ZR-75-1 cell line (74 microM compared to 38 microM). By using RT-PCR, expression of sulfotransferase (SULT)1A1 mRNA, but not of other SULTs investigated, showed a close correlation with resveratrol 3-O-sulfate formation which was particularly high in ZR-75-1 and very low in MDA-MD-231 cells. In conclusion, we demonstrate that SULT1A1-based biotransformation reduces the anticancer activity of resveratrol in breast cancer cells, which must be considered in humans following oral uptake of dietary resveratrol as a chemopreventive agent.
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Riches Z, Bloomer JC, Coughtrie MWH. Comparison of 2-aminophenol and 4-nitrophenol as in vitro probe substrates for the major human hepatic sulfotransferase, SULT1A1, demonstrates improved selectivity with 2-aminophenol. Biochem Pharmacol 2007; 74:352-8. [PMID: 17506995 DOI: 10.1016/j.bcp.2007.04.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 04/03/2007] [Accepted: 04/04/2007] [Indexed: 10/23/2022]
Abstract
Sulfation, catalysed by members of the cytosolic sulfotransferase (SULT) enzyme family, is important in xenobiotic detoxification and in the biosynthesis and homeostasis of many hormones and neurotransmitters. The major human phenol sulfotransferase SULT1A1 plays a key role in chemical defence, is widely expressed in the body and is subject to a common polymorphism that results in reduced protein levels. Study of these enzymes in vitro requires robust probe substrates, and we have previously shown measurement of activity with the widely used SULT1A1 substrate, 4-nitrophenol, does not accurately reflect protein expression. Additionally, the high degree of substrate inhibition observed with this compound further reduces its value as a probe for SULT1A1. Here we show that 2-aminophenol is a more suitable probe substrate for quantifying SULT1A1 activity in human liver. This compound is sulfated at a high rate (V(max) with purified recombinant SULT1A1=121nmol/(minmg) and shows strong affinity for the enzyme (K(m) with purified recombinant SULT1A1=9microM) and, importantly, is a very poor substrate for the other major SULT1 enzyme expressed in liver, SULT1B1 (with V(max) and K(m) values of 17nmol/(minmg) and 114microM, respectively). Experiments with purified recombinant human SULTs and a panel of 28 human liver cytosols demonstrated that 2-aminophenol shows limited substrate inhibition with SULT1A1, and V(max) values measured in liver cytosols correlated strongly with SULT1A1 enzyme protein levels measured by a quantitative immunoblot method. We therefore suggest that 2-aminophenol is a suitable substrate to use for quantifying SULT1A1 enzyme activity.
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Affiliation(s)
- Zoe Riches
- Division of Pathology & Neuroscience, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, Scotland, UK
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20
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Martin-Skilton R, Coughtrie MWH, Porte C. Sulfotransferase activities towards xenobiotics and estradiol in two marine fish species (Mullus barbatus and Lepidorhombus boscii): characterization and inhibition by endocrine disrupters. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2006; 79:24-30. [PMID: 16806523 DOI: 10.1016/j.aquatox.2006.04.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 04/25/2006] [Accepted: 04/27/2006] [Indexed: 05/10/2023]
Abstract
We have characterized hepatic phenol sulfotransferase (SULT) activities in two benthic fish species, Mullus barbatus and Lepidorhombus boscii, using p-nitrophenol, dopamine, 17beta-estradiol, 4-nonylphenol, and 1-naphthol as substrates. High affinity sulfation of 17beta-estradiol was observed in both species (Km=28-75 nM), suggesting the presence of a specific estrogen sulfotransferase that catalyzes the formation of estradiol-3 sulfate. Among the tested compounds, 1-naphthol was the most effective substrate for sulfation, with Vmax/Km ratios several hundred-fold higher than the other substrates examined. Both species sulfated the tested compounds, but only M. barbatus was able to sulfate dopamine. We also tested the inhibitory effects of common marine pollutants with estrogenic (4-nonylphenol) and androgenic (tributyltin, triphenyltin) properties on p-nitrophenol and 17beta-estradiol SULT activities. 4-Nonylphenol and triphenyltin inhibited sulfation of both substrates at micromolar concentrations in both species. However, tributyltin was only effective against SULTs from L. boscii, again at micromolar concentrations. The data indicate that M. barbatus and L. boscii are able to sulfate a range of xenobiotics and endogenous compounds, and inhibition of these activities by environmental pollutants may contribute to the known toxic effects of these compounds.
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Affiliation(s)
- Rebeca Martin-Skilton
- Environmental Chemistry Department, IIQAB-CSIC, C/Jordi Girona 18, 08034 Barcelona, Spain
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21
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Ohtake E, Kakihara F, Matsumoto N, Ozawa S, Ohno Y, Hasegawa S, Suzuki H, Kubota T. Frequency distribution of phenol sulfotransferase 1A1 activity in platelet cells from healthy Japanese subjects. Eur J Pharm Sci 2006; 28:272-7. [PMID: 16621480 DOI: 10.1016/j.ejps.2006.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Revised: 02/20/2006] [Accepted: 02/20/2006] [Indexed: 11/20/2022]
Abstract
AIMS To determine the distribution of sulfotransferase 1A1 (SULT1A1) activities, we used trans-4-hydroxytamoxifen (OHT) as a substrate to test samples from a Japanese population to examine whether the SULT1A1*2 allele can account for the wide distribution of OHT sulfating activity. We also studied genetic mutations other than the SULT1A1*2 allele to determine the cause of differences in SULT1A1 protein expression and activity. METHODS The subjects were 103 healthy Japanese adults. Identification of SULT1A1 genotypes was performed using a polymerase chain reaction-restriction fragment length polymorphism method. SULT1A1 activity in platelet cytosol was assayed using OHT as a substrate. SULT1A1 protein was detected using Western blotting analysis. Mutations other than SULT1A1*2 in the SULT1A1 gene were detected using sequencing analysis. RESULTS SULT1A1*2 allele frequency was found to be 16.5%, while SULT1A1 activity ranged from 63 to 1860pmol sulfated/h/mg platelet protein (260+/-241pmol sulfated/h/mg platelet protein, median+/-S.D.) using OHT as a substrate. The median values in subjects with SULT*1/*2 (221+/-113pmol sulfated/h/mg platelet protein, range 63-442, n=26) and SULT*2/*2 (124+/-66pmol sulfated/h/mg platelet protein, range 74-231, n=4) were significantly lower than that in subjects with SULT*1/*1 (303+/-267pmol sulfated/h/mg platelet protein, range 97-1859, n=73). A novel G148C mutation was found in one subject, who showed the lowest OHT sulfating activity, for a frequency of 0.49%. CONCLUSION There was wide variety of OHT sulfating activities found among the present healthy Japanese subjects. The SULT1A1*2 allele was found to be a common variant allele and was associated with decreased OHT sulfating activity. These observations may be related to inter-individual variations of OHT pharmacokinetics and the pharmacologic effects of tamoxifen seen in Japanese patients with breast cancer.
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Affiliation(s)
- Eiko Ohtake
- Department of Pharmacy, University of Tokyo Hospital, Faculty of Medicine, Tokyo, Japan
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22
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Wang LQ, Lehmler HJ, Robertson LW, James MO. Polychlorobiphenylols are selective inhibitors of human phenol sulfotransferase 1A1 with 4-nitrophenol as a substrate. Chem Biol Interact 2006; 159:235-46. [PMID: 16413005 DOI: 10.1016/j.cbi.2005.12.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 12/05/2005] [Accepted: 12/06/2005] [Indexed: 11/29/2022]
Abstract
Polychlorobiphenylols (OH-PCBs) were reported as potent inhibitors of estrogen sulfotransferase, thyroid hormone and 3-hydroxybenzo(a)pyrene sulfotransferases. The aim of this study was to examine the effects of selected OH-PCBs on SULT1A1 activity in human liver cytosol, measured with 4microM 4-nitrophenol, a concentration considered to be diagnostic for selectively detecting SULT1A1. All the OH-PCBs studied inhibited the sulfonation of 4-nitrophenol in human liver cytosol. Among the eighteen OH-PCBs studied, 3'-OH-CB3 (4-chlorobiphenyl-3'-ol) was the most potent inhibitor (IC(50): 0.73+/-0.15microM, mean+/-S.D., n=3). The least potent inhibitor studied was 6'-OH-CB35 (3,3',4-trichlorobiphenyl-6'-ol) with IC(50): 49.1+/-10.8microM. The IC(50) values of the other OH-PCBs studied ranged from 0.78 to 3.76microM. Some OH-PCBs with various inhibitory potencies with human liver cytosol were selected for study with recombinant human SULT1A1 and SULT1B1. These OH-PCBs showed more potent inhibition of 4-nitrophenol sulfonation with SULT1A1 than with human liver cytosol. The IC(50) values with human liver cytosol showed a perfect linear correlation with those found with SULT1A1 (r(2)=1), but not with SULT1B1 (r(2)=0.21). The results suggested that in these human samples SULT1A1 was predominantly responsible for the sulfonation of 4-nitrophenol, with very little or no contribution from SULT1B1. The kinetics of inhibition were studied with 4'-OH-CB165, which is similar in structure to OH-PCBs found in human blood. The 4'-OH-CB165 was a mixed noncompetitive-uncompetitive inhibitor (K(i)=1.80+/-0.2microM, K(ies)=0.16+/-0.02microM). Finally, it was demonstrated that the tested OH-PCBs were themselves only slowly sulfonated by human sulfotransferases in the presence of (35)S-PAPS, as measured by the production of (35)S-labeled metabolites. Although this series of 18 OH-PCBs was too small to draw conclusions about structure-potency relationships, this work demonstrated that several OH-PCBs were potent inhibitors of 4-nitrophenol sulfonation but poor substrates in human liver cytosol, and suggested that OH-PCBs may inhibit the sulfation rate of those xenobiotics sulfated by SULT1A1.
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Affiliation(s)
- Li-Quan Wang
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville 32610-0485, USA
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Falany JL, Pilloff DE, Leyh TS, Falany CN. Sulfation of raloxifene and 4-hydroxytamoxifen by human cytosolic sulfotransferases. Drug Metab Dispos 2005; 34:361-8. [PMID: 16381672 DOI: 10.1124/dmd.105.006551] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Raloxifene and 4-hydroxytamoxifen (4-OHT) are important estrogen-related drugs used in the treatment of osteoporosis and breast cancer. Sulfation is involved in the metabolism and inactivation of both compounds in human tissues, although the sulfotransferase (SULT) isoforms involved in their conjugation have not been well described. The ability of seven expressed SULT isoforms to sulfate raloxifene and 4-OHT was investigated. Raloxifene was conjugated by all seven SULT isoforms tested, whereas 4-OHT was conjugated only by SULTs 1A1, 1E1, and 2A1. Characterization of raloxifene and 4-OHT sulfation demonstrates that sulfation can occur at therapeutic concentrations. SULT1E1 displayed the lowest Km (0.2 microM) for 4-OHT sulfation and SULT2A1 the lowest (0.3 microM) for raloxifene sulfation. SULT1E1 was the only isoform exhibiting detectable levels of raloxifene disulfation activity. Modeling of the interactions of raloxifene in the active site of SULT1E1 indicates that both hydroxyl groups of raloxifene can be readily positioned in proximity to the sulfonyl group of 3'-phosphoadenosine 5'-phosphosulfate and the catalytically important His107 residue. Both raloxifene and 4-OHT sulfation activities were detectable in all human liver cytosols tested. 4-OHT sulfation was detected in cytosol prepared from endometrial biopsies of normal women obtained during the proliferative and secretory phases of the same menstrual cycle. In contrast, raloxifene sulfation was detectable only in secretory phase cytosols in association with SULT1E1 activity. In summary, several human SULT isoforms are capable of sulfating raloxifene and 4-OHT. Tissue-specific expression of the individual SULT isoforms may have important roles in the regulation of the activity of these compounds.
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Affiliation(s)
- Josie L Falany
- Department of Pharmacology and Toxicology, 1670 University Blvd, Volker Hall G133M, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Duanmu Z, Weckle A, Koukouritaki SB, Hines RN, Falany JL, Falany CN, Kocarek TA, Runge-Morris M. Developmental expression of aryl, estrogen, and hydroxysteroid sulfotransferases in pre- and postnatal human liver. J Pharmacol Exp Ther 2005; 316:1310-7. [PMID: 16339912 DOI: 10.1124/jpet.105.093633] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aryl- (SULT1A1), estrogen- (SULT1E1), and hydroxysteroid- (SULT2A1) sulfotransferases (SULTs) are active determinants of xenobiotic detoxication and hormone metabolism in the adult human liver. To investigate the role of these conjugating enzymes in the developing human liver, the ontogeny of immunoreactive SULT1A1, SULT1E1, and SULT2A1 expression was characterized in a series of 235 pre- and postnatal human liver cytosols ranging in age from early gestation to a postnatal age of 18 years. Interindividual variability in expression levels was apparent for all three SULTs in pre- and postnatal liver samples. Expression of the three SULTs displayed distinctly different developmental profiles. Semiquantitative Western blot analyses indicated that SULT1A1 and SULT2A1 immunoreactive protein levels were readily detectable in the majority of developmental human liver cytosols throughout the prenatal period. Whereas SULT1A1 expression did not differ significantly among the various developmental stages, SULT2A1 expression increased during the third trimester of gestation and continued to increase during postnatal life. By contrast, SULT1E1, a cardinal estrogen-inactivating enzyme, achieved the highest levels of expression during the earliest periods of gestation in prenatal male livers, indicating a requisite role for estrogen inactivation in the developing male. The present analysis suggests that divergent regulatory mechanisms are responsible for the differential patterns of hepatic SULT1A1, SULT1E1, and SULT2A1 immunoreactive protein levels that occur during pre- and postnatal human development, and implicates a major role for sulfotransferase expression in the developing fetus.
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Affiliation(s)
- Zhengbo Duanmu
- Institute of Environmental Health Sciences, Wayne State University, 2727 Second Avenue, Room 4000, Detroit, MI 48201, USA
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Aust S, Jaeger W, Klimpfinger M, Mayer K, Baravalle G, Ekmekcioglu C, Thalhammer T. Biotransformation of melatonin in human breast cancer cell lines: role of sulfotransferase 1A1. J Pineal Res 2005; 39:276-82. [PMID: 16150108 DOI: 10.1111/j.1600-079x.2005.00246.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The biologically active melatonin metabolite, 6-hydroxymelatonin (6-OHMel), is conjugated to form 6-hydroxymelatonin sulfate (6-OHMelS). To elucidate the role of the sulfotransferase (SULT) enzyme 1A1, considerably expressed in normal and malignant human breast cells, we measured the formation of 6-OHMelS by ELISA in hormone-dependent MCF-7 and hormone-independent MDA-MB231 (MDA) breast cancer cell lines after stable transfection with SULT1A1. In parent MDA cells, low SULT1A1 mRNA expression was associated with moderate 6-OHMelS formation as determined after application (24 hr) of 0.1 microM 6-OHMel. As expected, overexpression of SULT1A1 in MDA cells resulted in a 2.9- and 110-fold increase in 6-OHMelS in the cytosol and cellular supernatant respectively. Furthermore, 6.3- and 115-fold increases were observed after 0.5 microM, and 12.6- and 101-fold increases after 1 microM 6-OHMel respectively. In MCF-7 cells, because of high basal SULT1A1 expression, only two- to threefold increases in 6-OHMelS were observed after transfection with the enzyme. In total, 866 and 539 pmol/mg protein 6-OHMelS were formed from 1 microM 6-OHMel in SULT1A1 overexpressing MDA and MCF-7 cells, respectively, whereas application of 1 microM melatonin produced only <1% of 6-OHMelS. Possible interactions with the SULT1A1 substrate tamoxifen (tam), an anti-estrogen applied in the therapy of breast cancer, were also studied. A concentration of 1 microM tam increased 6-OHMelS formation by approximately threefold in the presence of 1 microM melatonin or 1 microM 6-OHMel respectively. However, no alterations were detected after application of 1 microM 4-hydroxy-tamoxifen. In summary, we demonstrate the importance of SULT1A1 for the biotransformation of 6-OHMel in human breast cancer cells. Our data further suggest that tam can modulate melatonin biotransformation.
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Affiliation(s)
- Sylvia Aust
- Center for Physiology and Pathophysiology, Medical University of Vienna, Vienna, Austria
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26
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Stanley EL, Hume R, Coughtrie MWH. Expression profiling of human fetal cytosolic sulfotransferases involved in steroid and thyroid hormone metabolism and in detoxification. Mol Cell Endocrinol 2005; 240:32-42. [PMID: 16024168 DOI: 10.1016/j.mce.2005.06.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Revised: 06/01/2005] [Accepted: 06/09/2005] [Indexed: 10/25/2022]
Abstract
Protection against chemical insult is essential for normal development of the fetus, however many detoxification enzymes are poorly expressed during fetal development. A major exception is the sulfotransferase (SULT) family, which appears to be widely expressed in the developing human. These enzymes also play a key role in biosynthesis and homeostasis of a number of hormones, including estrogens and iodothyronines. We therefore examined the enzyme activity, protein and mRNA expression of SULT 1A, 1B, 1C, 1E and 2A families in a variety of human fetal and adult tissues. Our results show that these SULTs are expressed in the human fetus, with most present at levels equivalent to or higher than the adult. As there are no isoform-selective substrates for SULTs 1B1 and 1C2 we used immunoblot analysis to show for the first time expression of SULT1B1 at high levels in fetal small intestine, and expression of SULT1C2 in fetal liver, kidney and small intestine. SULT1C2 was not expressed in adult liver or colon. Sulfotransferase expression in the developing fetus is therefore more widespread than in the adult, and this has significant implication for our understanding of human developmental physiology.
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Affiliation(s)
- Emma L Stanley
- Division of Pathology & Neuroscience, University of Dundee, Ninewells Hospital & Medical School, Scotland, UK
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Abstract
Sulfonation has a major function in modulating the biological activities of a wide number of endogenous and foreign chemicals, including: drugs, toxic chemicals, hormones, and neurotransmitters. The activation as well as inactivation of many xenobiotics and endogenous compounds occurs via sulfonation. The process is catalyzed by members of the cytosolic sulfotransferase (SULT) superfamily consisting of at least ten functional genes in humans. The reaction in intact cells may be reversed by arylsulafatase present in the endoplasmic reticulum. Under physiological conditions, sulfonation is regulated, in part, by the supply of the co-substrate/donor molecule 3'-phosphadensoine-5-phosphosulfate (PAPS), and transport mechanisms by which sulfonated conjugates enter and leave cells. Variation in the response of individuals to certain drugs and toxic chemicals may be related to genetic polymorphisms documented to occur in each of the above pathways. Sulfonation has a major function in regulating the endocrine status of an individual by modulating the receptor activity of estrogens and androgens, steroid biosynthesis, and the metabolism of catecholamines and iodothyronines Sulfonation is a key reaction in the body's defense against injurious chemicals and may have a major function during early development since SULTs are highly expressed in the human fetus. As with many Phase I and Phase II reactions, sulfonation may also serve as the terminal step in activating certain dietary and environmental agents to very reactive toxic intermediates implicated in carcinogenesis.
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Affiliation(s)
- Frederick C Kauffman
- Laboratory for Cellular and Biochemical Toxicology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA.
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Cui D, Booth-Genthe CL, Carlini E, Carr B, Schrag ML. HETEROTROPIC MODULATION OF SULFOTRANSFERASE 2A1 ACTIVITY BY CELECOXIB: PRODUCT RATIO SWITCHING OF ETHYNYLESTRADIOL SULFATION. Drug Metab Dispos 2004. [DOI: 10.1124/dmd.32.11.1260] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Schrag ML, Cui D, Rushmore TH, Shou M, Ma B, Rodrigues AD. SULFOTRANSFERASE 1E1 IS A LOW KM ISOFORM MEDIATING THE 3-O-SULFATION OF ETHINYL ESTRADIOL. Drug Metab Dispos 2004. [DOI: 10.1124/dmd.32.11.1299] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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30
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Abstract
Drug metabolites can uniquely contribute to therapeutic efficacy, toxicity and drug-drug interactions. Therefore, the rates of formation and clearance of each metabolite are crucially important parameters in the net therapeutic profile of new drugs. However, the recent appreciation for the importance of drug metabolism has made it apparent that the understanding of the fundamental kinetic and biophysical properties of the enzymes that are responsible for catalyzing these reactions, the cytochrome P450s, is incomplete. The need to fully comprehend the complex allosteric behavior of these enzymes has fostered increased scrutiny of cytochrome P450s, which has subsequently resulted in major changes in the way that these enzymes are perceived at the molecular level.
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Affiliation(s)
- William M Atkins
- Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, WA 98195-7610, USA.
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