Importance of UDP-glucuronosyltransferases 2A2 and 2A3 in tobacco carcinogen metabolism

Ryan T Bushey; Douglas F Dluzen; Philip Lazarus

doi:10.1124/dmd.112.049171

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Importance of UDP-glucuronosyltransferases 2A2 and 2A3 in tobacco carcinogen metabolism

Journal article

Open access

Peer reviewed

Importance of UDP-glucuronosyltransferases 2A2 and 2A3 in tobacco carcinogen metabolism

Ryan T Bushey, Douglas F Dluzen and Philip Lazarus

Drug metabolism and disposition, Vol.41(1), pp.170-179

01/2013

DOI: https://doi.org/10.1124/dmd.112.049171

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https://hdl.handle.net/2376/109533

PMCID: PMC3533432

PMID: 23086198

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Abstract

Glucuronosyltransferase - metabolism

Isoenzymes - metabolism

Tobacco - metabolism

Base Sequence

Humans

HEK293 Cells

Carcinogens - metabolism

DNA Primers

Reverse Transcriptase Polymerase Chain Reaction

Real-Time Polymerase Chain Reaction

UDP-glucuronosyltransferase A1 (UGT2A1) is expressed in the lung and exhibits activity against polycyclic aromatic hydrocarbons (PAHs), suggesting UGT2A1 involvement in the local metabolism of PAH tobacco carcinogens. The goal of the present study was to investigate the importance of two additional UGT2A enzymes, UGT2A2 and UGT2A3, in tobacco carcinogen metabolism. Real-time polymerase chain reaction suggested that wild-type UGT2A2 had the highest expression in the breast, followed by trachea > larynx > kidney. A novel splice variant of UGT2A2 lacking exon 3 (termed UGT2A2Δexon3) was investigated, with UGT2A2Δexon3 expression determined to be 25-50% that of wild-type UGT2A2 in all tissues examined. UGT2A3 was determined to be well expressed in the liver and colon, followed by pancreas > kidney > lung > tonsil > trachea > larynx. Cell homogenates prepared from human embryonic kidney (HEK)293 cells overexpressing wild-type UGT2A2 (termed UGT2A2_i1) exhibited glucuronidation activity, as observed by reverse-phase ultra-pressure liquid chromatography, against 1-hydroxy-(OH)-pyrene, 1-naphthol, and hydroxylated benzo(a)pyrene metabolites, whereas homogenates prepared from HEK293 cells overexpressing UGT2A3 only showed activity against simple PAHs like 1-OH-pyrene and 1-naphthol. Activity assays showed the UGT2A2Δexon3 protein (termed UGT2A2_i2) exhibited no detectable glucuronidation activity against all substrates examined; however, coexpression studies suggested that UGT2A2_i2 negatively modulates UGT2A2_i1 activity. Both UGT2A2 and UGT2A3 exhibited no detectable activity against complex PAH proximate carcinogens, tobacco-specific nitrosamines, or heterocyclic amines. These data suggest that, although UGT2A1 is the only UGT2A enzyme active against PAH proximate carcinogens (including PAH diols), both UGTs 2A1 and 2A2 play an important role in the local detoxification of procarcinogenic monohydroxylated PAH metabolites.

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Title: Importance of UDP-glucuronosyltransferases 2A2 and 2A3 in tobacco carcinogen metabolism
Creators: Ryan T Bushey - Department of Pharmacology, Penn State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
Douglas F Dluzen
Philip Lazarus
Publication Details: Drug metabolism and disposition, Vol.41(1), pp.170-179
Academic Unit: Pharmaceutical Sciences, Department of
Publisher: United States
Grant note: R01 DE013158 / NIDCR NIH HHS R01-CA164366 / NCI NIH HHS R01-DE13158 / NIDCR NIH HHS R01 CA164366 / NCI NIH HHS
Identifiers: 99900547224901842
Language: English
Resource Type: Journal article