
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Short Communications |
Cancer Prevention Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024
| Abstract |
|---|
|
|
|---|
| Introduction |
|---|
|
|
|---|
Polymorphisms have been identified in at least three of the human UGT2B genes: UGT2B4, UGT2B7, and UGT2B15 (7, 8, 9) . Reported nucleotide sequence differences in UGT2B4 lead to amino acid changes at positions 109, 396, and 458. The variant UGT2B4(L109,396D458), isolated from human liver, has leucine (L), instead of phenylalanine (F) residues at amino acids 109 and 396 (7 , 10) . A difference of two nucleotides also leads to another single amino acid change of aspartate (D) to glutamate (E) at position 458 (7) . UGT2B4 is primarily involved in the conjugation of catechol estrogens, bile acids (specifically hyodeoxycholic acid), and certain exogenous phytochemicals (7) . Both UGT2B4(D458) and (E458) are expressed in liver and a wide range of extrahepatic tissues, including those that are targets for steroid hormones; however, there is no apparent difference in substrate specificity between the two forms (7) . Lévesque et al. (7) reported that in a sample of 26 Caucasian individuals, the frequency of the variant E458 allele was 0.385. The authors did not detect the presence of the UGT2B4(L109,396D458) variant in any of the tissues or genomic DNA sampled; however, they suggested that this may be a rare allele not found in their sample population.
In UGT2B7, there is an amino acid change from histidine (H) to tyrosine
(Y) at amino acid 268 (8)
, the proposed location of the
substrate-binding site (11)
. The prevalence of the two
alleles and a corresponding phenotypic difference have not been
determined. UGT2B7 glucuronidates 4-hydroxycatechol estrogens
(12)
and mono- and dihydroxylated androgens with a
hydroxyl group in the 3
, 6
, and 17ß positions; however, UGT2B7
has the highest activity toward steroids containing a 3
-hydroxy
moiety (13
, 14) . UGT2B7 expression has been detected in
liver, kidney, pancreas, brain, and the gastrointestinal tract
(15, 16, 17)
.
In UGT2B15, a thymine in place of a guanine leads to
an amino acid change at position 85 from aspartic acid (D) to tyrosine
(Y; Ref. 9
). UGT2B15 is expressed in numerous human
tissues (e.g., liver, kidney, testis, mammary gland,
prostate, and lung; Ref. 9
). This isozyme catalyzes the
glucuronidation of a wide range of substrates, including simple
phenolic compounds, drugs, and C19 steroids, such
as 5
-androstane-3
,17ß-diol and
dihydrotestosterone, at the 17ß position (18
, 19)
. Coumarins, flavonoids, and anthraquinones, phytochemicals
that are present in high amounts in certain plant foods, also are
glucuronidated by UGT2B15 (18)
. To date, only one study
has examined the prevalence of the UGT2B15 polymorphic
allele; Lévesque et al. (9)
determined
that of a sample of 27 Caucasians, 6 (19%) were homozygous for
Y85
(Y85/Y85), 5
(22%) were homozygous for D85
(D85/D85),
and 16 (73%) had both alleles
(D85/Y85).
The purpose of our work was to determine the prevalence of the described genetic polymorphisms in UGT2B4, UGT2B7, and UGT2B15 in a sample of individuals from the Seattle, Washington area.
| Materials and Methods |
|---|
|
|
|---|
All participants had venous blood samples drawn for genomic DNA collection. DNA was extracted from lymphocytes according to standard methods using a proteinase K digestion followed by phenol-chloroform extractions (20) . A demographic and health questionnaire was completed. Information requested on the questionnaire included usual diet (e.g., vegetarian, diabetic, low-fat), food preferences, alcohol intake, medical history, vitamin/mineral and herbal supplement information, usual activity, medications, environmental exposures, and ethnic/racial background. The study design was approved by the Institutional Review Board: Human Subjects Committee at the Fred Hutchinson Cancer Research Center. Informed written consent was obtained from all participants prior to the start of the study.
Determination of UGT2B4, UGT2B7, and UGT2B15 Genotypes
The UGT2B4 F109L,
F396L, and
D458E; UGT2B7; and
UGT2B15 genotypes were determined using an oligonucleotide
ligation assay (21
, 22) . Amplification of the correct PCR
fragments was confirmed by sequencing.
UGT2B4.
To distinguish the
UGT2B4(D458E) (GenBank accession nos.
AJ005162 and AF064200, respectively) and
UGT2B4(L109,396,D458)
(GenBank accession no. AF081793) alleles, the polymorphisms at amino
acids 109, 396, and 458 were determined. Three fragments were amplified
by PCR using the following primers: for
F109L, FP1 (5'-GAGGATATTATCAAGCAGCT-3')
and RP1 (5'-CAGCATCTGCAAGAACAACA-3'); for F396L,
FP2 (5'-ACCTCATGGTGGAGCCAATG-3') and RP2 (5'-ACATTGTGTGGAAGTCCAAA-3');
and for D458E, FP3 (5'-TTCATCATGATCAACCAGTGA-3')
and RP3 (5'-CTTCCAGCCTCAGACGTAAT-3'). The PCR reactions contained
10 mM Tris-HCl (pH 8.3), 50
mM KCl, 1.5 mM
MgCl2, 0.001% gelatin, 50 ng/µl BSA, 200
µM deoxynucleotide triphosphates (100
µM for F109L and
D458E), 150 nM
amplification primers, 100 ng of genomic DNA, and 0.5 units of AmpliTaq
DNA polymerase (Perkin-Elmer, Foster City, CA). The cycling conditions
on a PTC-100 thermal cycler (MJ Research, Inc., Watertown, MA) were as
follows: (a) for F109L and
F396L, 94°C for 5 min, followed by 30 cycles
of 94°C for 30 s, 58°C for 45 s, and 72°C for 60 s
and 1 cycle of 72°C for 5 min; and (b) for
D458E, 94°C for 5 min, followed by 30 cycles
of 94°C for 30 s, 60°C for 45 s, and 72°C for 60 s
and 1 cycle of 72°C for 5 min.
The F109L,
F396L, and
D458E polymorphisms were
determined by oligonucleotide ligation assay using the primers listed
in Table 1
. The modification for the allele-specific primers was 5'-biotin and
5'-phosphate and 3'-digoxigenin for the common primer. For the
ligation, the PCR reactions were diluted with 35 µl of 0.1% Triton
X-100. The ligation reactions consisted of 10 µl of diluted PCR
product, and 10 µl of 40 mM Tris-HCl (pH 8.0),
20 mM MgCl2, 25
mM KCl, 2 mM DTT, 2
mM NAD+, 0.1% Triton
X-100, 16 fmol/µl biotinylated primer, 16 fmol/µl common primer,
and 0.015 units of thermostable ligase (Epicentre Technologies,
Madison, WI). The cycling conditions for the ligation were as follows:
15 cycles of 93°C for 30 s and 58°C for 2 min. The reaction
was stopped with 10 µl of a buffer containing 0.1
M EDTA (pH 8.0) and 0.1% Triton X-100. The
ligation reactions were then transferred into streptavidin-coated
96-well plates. After incubation at room temperature for 60 min, the
plates were washed twice with 10 mM NaOH
containing 0.05% Tween 20, followed by two washes with 200 µl of 100
mM Tris-HCl (pH 7.5), 150
mM NaCl, and 0.05% Tween 20. The plates were
then incubated with 40 µl of a 1000-fold dilution of antidigoxigenin
Fab fragment-phosphatase conjugate (0.75 units/µl; Boehringer
Mannheim, Indianapolis, IN) for 30 min at room temperature. After four
washes with 100 mM Tris-HCl (pH 7.5), 150
mM NaCl, and 0.05% Tween 20, the Life
Technologies amplification system was applied for the color reaction
according to the manufacturers recommendations. The absorbance at 490
nm was recorded using a SpectraMax 250 plate reader (Molecular Devices,
Sunnyvale, CA).
|
The primers for the ligation reactions were as follows: H268 (5'-CCTGGAATTTTCAGTTTCCTC-3'); Y268 (5'-CCTGGAATTTTCAGTTTCCAT-3'); and common primer (5'-ATCCACTCTTACCAAATGTTG-3'). The modifications for the primers were 5'-biotin for H268- and Y268-specific primers and 5'-phosphate and 3'-digoxigenin for the common primer. The ligation reactions were as described for UGT2B4.
UGT2B15(D85Y).
The UGT2B15(D85Y) polymorphism
consists of a G-to-T point mutation, resulting in an amino acid change
from aspartic acid (D) to tyrosine (Y) at amino acid 85
(9)
. Primers 5'-GTTACTTTAGCTCTGGAAGC-3' and
5'-AGAGCTTGTTACTGTAGTCAT-3' were used to amplify a 333-bp fragment of
the UGT2B15 gene containing the mutation. The PCR reactions
contained 10 mM Tris-HCl (pH 8.3), 50
mM KCl, 1.5 mM
MgCl2, 0.001% gelatin, 50 ng/µl BSA, 100
µM deoxynucleotide triphosphates, 100
nM amplification primers, 100 ng of genomic DNA,
and 0.5 units of AmpliTaq DNA polymerase (Perkin-Elmer). The cycling
conditions on a PTC-100 thermal cycler (MJ Research) were as follows:
94°C for 5 min, followed by 35 cycles of 94°C for 30 s, 60°C
for 45 s, 72°C for 60 s and 1 cycle of 72°C for 5 min.
The ligation was performed as described above for UGT2B7. The ligation primers for UGT2B15 were D85 (5'-TCCTACATCTTTAACTAAAAATG-3'); Y85 (5'-TCCTACATCTTTAACTAAAAATT-3'); and common primer (5'-ATTTGGAAGATTCTCTTCTGAA-3'). The modifications for the primers were 5'-biotin for D85- and Y85-specific primers and 5'-phosphate and 3'-digoxigenin for the common primer.
Statistical Analysis
Statistical analyses were conducted using SAS software (Version
6.12 for Windows; SAS Institute Inc., Cary, NC). We measured
differences between observed and expected
UGT2B4(D458E),
UGT2B7(H268Y), and
UGT2B15(D85Y) genotype
frequencies using the
2 test and compared
genotype frequencies between individuals of Asian and Caucasian
background using Fishers exact test.
| Results |
|---|
|
|
|---|
The UGT2B4(D458E),
UGT2B7(H268Y), and
UGT2B15(D85Y) allele and
genotype frequencies are presented in Table 2
. We did not detect the presence of the
UGT2B4(L109,396,D458)
allelic variant in any of the samples. The allele frequencies were
significantly different (P < 0.02) between individuals
of Caucasian and Asian descent for all three polymorphisms. Genotype
frequencies for the UGT2B4(D458E),
UGT2B7(H268Y), and
UGT2B15(D85Y) polymorphisms also
differed significantly by ethnic group (P < 0.0001,
P = 0.0002, and P = 0.02,
respectively). All of the Asians were homozygous wild type
(D458/D458) for
UGT2B4. For UGT2B7, almost 60% of individuals of
Asian background were
H268/H268 and
only 9% were
Y268/Y268,
whereas among the Caucasians only 22% were
H268/H268 and
29% were Y268/Y268.
Similarly, for UGT2B15, 47% of Asians were
D85/D85 and
19% were
Y85/Y85,
whereas 22% of Caucasians were
D85/D85 and
32% were
Y85/Y85. Within
the Asian and Caucasian samples, the genotype frequencies were in
Hardy-Weinberg equilibrium.
|
| Discussion |
|---|
|
|
|---|
13 individuals if the prevalence rate was similar to that in
Caucasians. The variant UGT2B7Y268 and
UGT2B15Y85 alleles also were significantly
more common among Caucasians compared with Asians. The prevalence of
the UGT2B7
Y268/Y268 genotype
was 3-fold higher in Caucasians than Asians. Similarly, the prevalence
of the UGT2B15
Y85/Y85 genotype was
1.7-fold higher in Caucasians than in Asians and also may be higher in
our sample of Caucasians (32%) than in the sample of 27 Caucasians
genotyped by Lévesque et al. (9)
, of
which 19% were homozygous
Y85/Y85. The UGT2B4(L109,396,D458) variant allele appears to be very rare. Lévesque et al. (7) did not find expression of the UGT2B4(L109,396,D458) transcript in any tissue samples tested, nor did they find the allele in 26 samples of genomic DNA. Similarly, in our 10-fold larger sample, we also did not find any individuals with this allele.
The extent to which the 2B polymorphisms may influence xenobiotic and endogenous steroid conjugation remains to be determined. In UGT2B4, substitution of E for D at 458 probably is a relatively minor amino acid modification, and stably expressed UGT2B4(D458) and UGT2B4(E458) in HK293 cells show similar substrate specificity (7) . In the case of UGT2B7(H268Y), H-to-Y constitutes a nonconservative amino acid change in the region of the substrate binding site. Consequently, Jin et al. (8) postulated that the polymorphism would probably affect substrate specificity. In addition, they reported that UGT2B7(Y268), but not (H268), conjugated menthol and androsterone. More recently, Cheng et al. (12) and Coffman et al. (23) reported that in the case of catechol estrogens, androsterone, opioids, and several xenobiotics, substrate glucuronidation efficiency did not differ between cells designed to express UGT2B7(H268) or (Y268).
The polymorphism in
UGT2B15(D85Y) does not appear to
alter specificities among the substrates tested to date, but it does
increase the Vmax by 2-fold and may
contribute to individual variability in glucuronidation observed with
some drugs and other compounds (24)
. Specifically,
UGT2B15(Y85) has a higher
Vmax than
UGTB15(D85) for
5
-androstane-3
,17ß-diol and dihydrotestosterone
(9)
. Given the high prevalence of the variant allele
(Y85; 50%) and the small differences
in kinetics, Lévesque et al. (9)
suggested that differences in steroid hormone metabolism are unlikely
to be observed in vivo, but that this polymorphism may
contribute to individual variability in xenobiotic glucuronidation. On
that basis, the implications of carrying the
Y85 homozygous genotype are unclear;
however, if the Vmax is higher for the
numerous phytochemicals that are metabolized by UGT2B15, one might
postulate that these compounds would be cleared more rapidly and their
potential chemopreventive effects would be reduced.
In conclusion, we have detected a high prevalence of the polymorphisms in UGT2B4(D458E), UGT2B7(H268Y), and UGT2B15(D85Y) in a small, convenient sample of healthy individuals. In addition, we observed significant ethnic differences between Asians and Caucasians in the distribution of these polymorphisms. The relationship between UGT2B polymorphisms and cancer risk has not been explored; however, the role of UGT2Bs in the conjugation and excretion of steroid hormones and the international differences in risk of hormone-dependent cancers suggest that these enzymes may be important candidates for additional study. Whether the genotypic differences explain, in part, observed ethnic differences in steroid hormone profiles and drug metabolism remains to be determined. Our results suggest that further investigation of these polymorphisms in large, multiethnic cohorts is warranted.
| Footnotes |
|---|
1 Supported by NCI Grant R01 CA70913 (to J. D. P.) and Fred Hutchinson Cancer Research Center. ![]()
2 To whom requests for reprints should be
addressed, at Fred Hutchinson Cancer Research Center, 1100 Fairview
Avenue North, MP-900, Seattle, WA 98109-1024. Phone: (206) 667-6580;
Fax: (206) 667-7850; E-mail: jlampe{at}fhcrc.org ![]()
3 The abbreviation used is: UGT,
UDP-glucuronosyltransferase. ![]()
Received 7/19/99; revised 12/15/99; accepted 12/23/99.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
C. Swanson, M. Lorentzon, L. Vandenput, F. Labrie, A. Rane, J. Jakobsson, S. Chouinard, A. Belanger, and C. Ohlsson Sex Steroid Levels and Cortical Bone Size in Young Men Are Associated with a Uridine Diphosphate Glucuronosyltransferase 2B7 Polymorphism (H268Y) J. Clin. Endocrinol. Metab., September 1, 2007; 92(9): 3697 - 3704. [Abstract] [Full Text] [PDF] |
||||
![]() |
O. Bernard, J. Tojcic, K. Journault, L. Perusse, and C. Guillemette Influence of Nonsynonymous Polymorphisms of UGT1A8 and UGT2B7 Metabolizing Enzymes on the Formation of Phenolic and Acyl Glucuronides of Mycophenolic Acid Drug Metab. Dispos., September 1, 2006; 34(9): 1539 - 1545. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. R. Ross, J. Riley, C. Quigley, and K. I. Welsh Clinical Pharmacology and Pharmacotherapy of Opioid Switching in Cancer Patients Oncologist, July 1, 2006; 11(7): 765 - 773. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. E. Kuehl, J. Bigler, J. D. Potter, and J. W. Lampe GLUCURONIDATION OF THE ASPIRIN METABOLITE SALICYLIC ACID BY EXPRESSED UDP-GLUCURONOSYLTRANSFERASES AND HUMAN LIVER MICROSOMES Drug Metab. Dispos., February 1, 2006; 34(2): 199 - 202. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Jakobsson, L. Ekstrom, N. Inotsume, M. Garle, M. Lorentzon, C. Ohlsson, H.-K. Roh, K. Carlstrom, and A. Rane Large Differences in Testosterone Excretion in Korean and Swedish Men Are Strongly Associated with a UDP-Glucuronosyl Transferase 2B17 Polymorphism J. Clin. Endocrinol. Metab., February 1, 2006; 91(2): 687 - 693. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. E. Kuehl, J. W. Lampe, J. D. Potter, and J. Bigler GLUCURONIDATION OF NONSTEROIDAL ANTI-INFLAMMATORY DRUGS: IDENTIFYING THE ENZYMES RESPONSIBLE IN HUMAN LIVER MICROSOMES Drug Metab. Dispos., July 1, 2005; 33(7): 1027 - 1035. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Saeki, Y. Saito, H. Jinno, T. Tanaka-Kagawa, A. Ohno, S. Ozawa, K. Ueno, S. Kamakura, N. Kamatani, K. Komamura, et al. SINGLE NUCLEOTIDE POLYMORPHISMS AND HAPLOTYPE FREQUENCIES OF UGT2B4 AND UGT2B7 IN A JAPANESE POPULATION Drug Metab. Dispos., September 1, 2004; 32(9): 1048 - 1054. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. H. Court, Q. Hao, S. Krishnaswamy, T. Bekaii-Saab, A. Al-Rohaimi, L. L. von Moltke, and D. J. Greenblatt UDP-Glucuronosyltransferase (UGT) 2B15 Pharmacogenetics: UGT2B15 D85Y Genotype and Gender Are Major Determinants of Oxazepam Glucuronidation by Human Liver J. Pharmacol. Exp. Ther., August 1, 2004; 310(2): 656 - 665. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. G. Wells, P. I. Mackenzie, J. Roy Chowdhury, C. Guillemette, P. A. Gregory, Y. Ishii, A. J. Hansen, F. K. Kessler, P. M. Kim, N. Roy Chowdhury, et al. GLUCURONIDATION AND THE UDP-GLUCURONOSYLTRANSFERASES IN HEALTH AND DISEASE Drug Metab. Dispos., March 1, 2004; 32(3): 281 - 290. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Girard, O. Barbier, G. Veilleux, M. El-Alfy, and A. Belanger Human Uridine Diphosphate-Glucuronosyltransferase UGT2B7 Conjugates Mineralocorticoid and Glucocorticoid Metabolites Endocrinology, June 1, 2003; 144(6): 2659 - 2668. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Y. Zhang, J. Zhan, C. S. Cook, R. M. Ings, and A. P. Breau Involvement of Human UGT2B7 and 2B15 in Rofecoxib Metabolism Drug Metab. Dispos., May 1, 2003; 31(5): 652 - 658. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. H. Court, S. X. Duan, C. Guillemette, K. Journault, S. Krishnaswamy, L. L. von Moltke, and D. J. Greenblatt Stereoselective Conjugation of Oxazepam by Human UDP-Glucuronosyltransferases (UGTs): S-Oxazepam Is Glucuronidated by UGT2B15, While R-Oxazepam Is Glucuronidated by UGT2B7 and UGT1A9 Drug Metab. Dispos., November 1, 2002; 30(11): 1257 - 1265. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Gsur, M. Preyer, G. Haidinger, G. Schatzl, S. Madersbacher, M. Marberger, C. Vutuc, and M. Micksche A Polymorphism in the UDP-Glucuronosyltransferase 2B15 Gene (D85Y) Is Not Associated with Prostate Cancer Risk Cancer Epidemiol. Biomarkers Prev., May 1, 2002; 11(5): 497 - 498. [Full Text] [PDF] |
||||
![]() |
R. Elsby, J. L. Maggs, J. Ashby, and B. K. Park Comparison of the Modulatory Effects of Human and Rat Liver Microsomal Metabolism on the Estrogenicity of Bisphenol A: Implications for Extrapolation to Humans J. Pharmacol. Exp. Ther., April 1, 2001; 297(1): 103 - 113. [Abstract] [Full Text] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Cancer Research | Clinical Cancer Research |
| Cancer Epidemiology Biomarkers & Prevention | Molecular Cancer Therapeutics |
| Molecular Cancer Research | Cancer Prevention Research |
| Cancer Prevention Journals Portal | Cancer Reviews Online |
| Annual Meeting Education Book | Meeting Abstracts Online |