From the Institute of Endocrinology, Tel Aviv Sourasky Medical Center,
The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (D.S., A.J.,
E.K., N.S.) and Department of Biological Regulation, The Weizman Institute of
Science, Rehovot (F.K., Y.A.-Z.), Israel.
Correspondence to N. Stern, MD, Institute of Endocrinology, Tel Aviv-Sourasky Medical Center, 6 Weizman St, Tel Aviv 64239, Israel.
The present study was undertaken to explore the effects of
estrogens and androgens on DNA synthesis and CK activity in human
endothelial cells and VSMCs. The results are
consistent with complex, dose-dependent, and cell-specific in
vitro effects of both E2 and DHT on proliferative
activity in the vascular wall.
Cell Cultures
Endothelial Cells
Detection of Estrogen Receptors
Assessment of DNA Synthesis
CK Extraction and Assay
Statistical Analysis
Modulation of DNA Synthesis by Gonadal Steroids
VSMCs
Regardless of the variable effect on DNA synthesis,
E2 and DHT (but not progesterone)
dose-dependently stimulated the specific activity of CK in both cell
types (Figure 3
Interaction Between Gonadal Steroids and PDGF or IGF-1
VSMCs
Effect of Antiestrogens and Flutamide on DNA Synthesis
VSMCs
Effect of Antiidiotypic Antiestrogen Antibody 1D5 and
Monoclonal Antiestrogen Antibody E15
The monoclonal, high-affinity antiestradiol antibody E15
(previously found to enhance E2
activity11 ) had no effect on DNA synthesis
(Figure 9
The specificity of estradiol's interaction with VSMCs and E304
cells in the present work is supported by several findings. First,
both cell types contained nuclear estradiol receptors. Second, under
various experimental conditions the combined effects of estradiol and
antiestrogens were consistent with competitive inhibition. For
example, both estradiol and TAM (or RAL) increased DNA synthesis, but
in accordance with observations in other estrogen responsive
tissues,18 this effect was not apparent in the
presence of both the agonist and the antagonist. Similarly,
both estradiol and estrogen antagonists (TAM and RAL)
increased CK activity in E304 cells and VSMCs, but these actions did
not persist when estradiol and these antagonists were added
simultaneously to the same cultures. Third, antiidiotypic
antiestrogen antibodies shown in previous studies to possess
estrogen-mimetic activity19 elicited a
stimulatory effect on DNA synthesis and CK activity in E304 cells and
inhibited [3H]thymidine incorporation in VSMCs,
thus exerting the same cell-specific effects induced by estradiol
itself. Fourth, the F(ab')2 fragment of the
antiidiotypic antiestrogen antibody 1D5 inhibited
the effects of estradiol on DNA synthesis in E304 cells as well as in
VSMCs. Finally, the Fab' proteolytic fragment of the high-affinity
antiestradiol antibody E15 blocked estradiol-dependent effects on DNA
synthesis and CK-specific activity in both E304 cells and VSMCs as
observed in other cell types.11 Although we did
not establish which type of estrogen receptor is involved, recent
observations indicating that estradiol inhibits VSMC proliferation
after balloon injury in transgenic mice lacking the
Our results indicate that overall, estradiol induces opposing effects
on DNA synthesis in endothelial cells and VSMCs.
However, in VSMCs, estradiol acts in a bimodal fashion, enhancing
[3H]thymidine incorporation at very low
concentrations (prepubertal and postmenopausal range) while inhibiting
DNA synthesis at high concentrations such as those attained during the
ovulatory phase. Whether this bimodal dose dependency is unique to
cells derived from umbilical vessels or rather represents a
general phenomenon in human arterial tissue must be
addressed in further studies. Of note is the finding that regardless of
whether DNA synthesis was stimulated or inhibited, CK activity was
stimulated in a dose-dependent fashion in both cell types, thus
suggesting energy-requiring responses.
The interaction between estradiol and two different growth factors
acting in the vasculature, PDGF and IGF-1, further underscores the
differential effect of estrogen in endothelial cells
and VSMCs. Estradiol entirely blocked the increase in
[3H]thymidine incorporation into DNA induced by
PDGF and IGF-1, whereas in E304 cells these effects were further
enhanced in the presence of estradiol. Because IGF-1 and PDGF are
likely involved in the proliferative response of VSMCs to various
stimuli such as angiotensin II, endothelial
injury, and platelet aggregation, the potent antiproliferative
effect of estradiol, reducing PDGF- and IGF-1–dependent DNA synthesis
to below basal levels, may have considerable
pathophysiological significance.
Although some antiestrogens may confer cardiovascular
protection,21 little is known with respect to
their mode of action in the vasculature. The finding that TAM and RAL
indeed mimic the effect of estradiol on DNA synthesis in both
endothelial cells and VSMCs suggests one potential
mechanism by which their vascular effect might take place. Notably,
however, not all estrogen-mimetic effects of antiestrogens are
necessarily conserved in the presence of estradiol, as is exemplified
by the loss of stimulation of [3H]thymidine
incorporation when both agonists and antagonists are
present.
To our knowledge, this is the first report of an androgenic inhibition
of DNA synthesis in human VSMCs and stimulation in
endothelial cells. The antiandrogen flutamide
effectively blocked these effects while exerting no effect on its own.
The observation that DHT modulates DNA synthesis in both VSMCs and
endothelial cells in a manner that closely resembles
the action of estrogen, albeit at a higher concentration range, was
somewhat unexpected. Given that testosterone concentrations in vivo are
10 to 100 times higher than those of estradiol, DHT modulation of DNA
synthesis in this study is operative at
physiological levels. However, attempts to discern
the effects of estrogens and androgens in the vasculature in vivo are
inevitably complicated by the fact that androgen-free or estrogen-free
environments practically do not exist in adult human subjects.
In summary, estradiol and DHT modulate DNA synthesis in human
vascular cells in a parallel fashion. Their effects in VSMCs are
bimodal, inducing stimulation at low concentrations and inhibition at
high concentrations. In contrast, [3H]thymidine
incorporation into DNA by cells of endothelial origin
is positively influenced by both estradiol and DHT. Antiestrogens alone
exert estrogen-mimetic effects, but their mode of action is more
complex in the presence of estradiol. The interactions between
estrogens, androgens, PDGF, and IGF-1 may be important for vascular
wall repair and remodeling.
Received December 9, 1997;
first decision January 6, 1998;
accepted March 3, 1998.
© 1998 American Heart Association, Inc.
Scientific Contributions
Effects of Gonadal Steroids and Their Antagonists on DNA Synthesis in Human Vascular Cells
Abstract
Top
Abstract
Introduction
Methods
Results
Discussion
References
Abstract—The
cardiovascular effect of estrogen is currently under
intense investigation, but the role of androgens in vascular biology
has attracted little attention. Because endothelial
repair and vascular smooth muscle cell (VSMC) proliferation affect
atherogenesis, we analyzed the effects of 17ß-estradiol
(E2), dihydrotestosterone (DHT), and sex hormone
antagonists on DNA synthesis in human umbilical VSMCs and
in E304 cells (a human umbilical endothelial cell
line). In VSMCs, both E2 and DHT had a biphasic effect on
[3H]thymidine incorporation into DNA: low concentrations
(0.3 nmol/L for E2, 3 nmol/L for DHT) stimulated
[3H]thymidine incorporation (+35% and +41%,
respectively), whereas high concentrations (30 nmol/L for
E2, 300 nmol/L for DHT) inhibited
[3H]thymidine incorporation (-40%). In contrast,
E2 (0.3 to 300 nmol/L) and DHT (3 to 3000 nmol/L)
dose-dependently enhanced [3H]thymidine incorporation in
E304 cells (peak, +85% for both). In VSMCs, high concentrations of
E2 and DHT inhibited platelet-derived growth factor
(PDGF)–or insulin-like growth factor (IGF-1)–induced DNA synthesis
(-50% to 80%), whereas PDGF- or IGF-1–dependent DNA synthesis in
E304 cells was further increased by E2. The antiestrogens
tamoxifen and raloxifene mimicked the effects of E2 on DNA
synthesis in both VSMCs and E304 cells. However, when coincubated with
a stimulatory concentration of E2 (0.3 nmol/L), tamoxifen
and raloxifene blocked E2-induced
[3H]thymidine incorporation in E304 cells but not in
VSMCs. Finally, the androgen antagonist flutamide inhibited
the biphasic effects of DHT on VSMCs and blocked the increase in DNA
elicited by DHT in E304 cells. The results suggest complex,
dose-dependent, and cell-specific interactions of estrogens, androgens,
and their respective antagonists in the control of cellular
proliferation in the vascular wall. Gonadal steroid–dependent
inhibition of VSMC proliferation and stimulation of
endothelial replication may contribute to vascular
protection and remodeling responses to vascular injury.
Key Words: estradiol • dihydrotesterone • muscle, smooth, vascular • tamoxifen • raloxifene • flutamide
Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
References
Animal and human
studies indicate that estrogens are protective against coronary
atherosclerosis. Multiple potential mechanisms may be
involved, such as favorable effects on lipids,1
fibrinolysis,2 coronary
flow,3 4 and myocardial
contractility.5 Although recent
evidence suggests the existence of both estrogen and androgen receptors
in VSMCs and endothelial cells,6
the precise biological role of sex hormones in either cell type is
currently incompletely understood. There are well-known examples of
estrogenic and/or androgenic control of cell growth and proliferation
in classic target organs for sex hormone action. Because
endothelial repair and VSMC proliferation have defined
pathophysiological roles in vascular injury and
atherogenesis, the potential modulation of such processes by sex
hormones is of obvious interest. In several tissues, the effects of
estrogen, including growth modulation, are linked to the induction of
CK activity, and this has been used as a general genomic response
marker for gonadal steroids. CK is involved in cellular energy
buffering and is closely related to changes in cell replication rate in
various cell types.7 8 9
Methods
Top
Abstract
Introduction
Methods
Results
Discussion
References
Reagents
E2, DHT, progesterone, IGF-1, and PDGF
were purchased from Sigma Chemical Co. TAM was the gift of Dr A.
Wakeling (Xeneca Ltd, Macclefield, UK). TMI was obtained from Dr A.
Beigon (Pharmos Ltd, Rehovot, Israel). RAL was the gift of Dr B.
Fournier (Ciba-Geigy Ltd, Basel, Switzerland). The antiidiotypic
antiestrogen antibody 1D5 and its
F(ab')2 and Fab' fragments were prepared by us,
as previously described.10 The monoclonal
antiestradiol antibody E15 was raised in mice by us and characterized
as previously described.11 The Fab' monomer of
E15 was prepared and analyzed as reported
elsewhere.11
Umbilical Artery Smooth Muscle Cells
The use of human umbilical cords was approved by our
institution's human subject committee. Umbilical VSMCs were prepared
as previously described with minor
modifications.12 In brief, umbilical cords were
collected shortly after delivery, and arteries were dissected, cleaned
of blood and adventitia, and cut into tiny slices (1 to 3 mm). The
segments were kept in culture in Medium 199 containing 20% fetal calf
serum, glutamine, and antibiotics. Cell migration was detected within 5
to 7 days. Cells were fed twice a week and, on confluence, trypsinized
and transferred to 24-well dishes. Cells were used only at passages 1
to 3 when expression of smooth muscle actin was clearly
demonstrable.12
E304 cells, an endothelial cell line derived
from a human umbilical vein, were obtained from American Type Culture
Collection and grown in Medium 199 containing 10% fetal calf serum,
glutamine, and antibiotics.
Cultured cells were washed with 0.5 mL cold methanol,
fixed by incubating the cells with 1 mL methanol at -20°c, and then
washed twice with 1 mL of cold PBS for 5 minutes at 0°C. The cells
were then incubated with 250 µL FITC-labeled monoclonal antiidiotypic
antiestrogen antibody 1D5 directed against the
steroid binding domain of the estrogen receptor for 1 hour at 0°C in
the dark. After the incubation, cells were washed twice with cold PBS
for 5 minutes. The labeled receptors were visualized by
fluorescence microscopy. Control cultures were incubated in the
same way with FITC-labeled IgG.10
Cells were grown until subconfluence and then treated with
various hormones or agents as indicated. Twenty-two hours later,
[3H]thymidine (thymidine
[methyl-3H], 50 Ci/mmol, 1 mCi/mL, ICN
Pharmaceutical Inc) was added for 2 hours. Cells were then treated with
10% ice-cold trichloroacetic acid (TCA) for 5 minutes and washed twice
with 5% TCA and then with cold ethanol. The cellular layer was
dissolved in 0.3 mL of 0.3N NaOH, the samples were collected, and
[3H]thymidine incorporation into DNA was
determined.9
Cells were treated for 4 hours with the various hormones and
agents as specified and were then scraped off the culture dishes and
homogenized by freezing and thawing three times in an
extraction buffer as previously described.9
Supernatant extracts were obtained by centrifugation of
homogenates at 14000g for 5 minutes at 4°C in
an Eppendorf microcentrifuge. CK was determined by a coupled
spectrophotometric assay (Sigma) as described
previously.8 Protein was determined by Coomassie
blue dye binding using bovine serum albumin as the
standard.14
Comparisons between the control and various treatments were made
by ANOVA.
Results
Top
Abstract
Introduction
Methods
Results
Discussion
References
Estrogen Receptors
As shown in Figure 1
, incubation of
VSMCs and E304 cells with the FITC-labeled 1D5,
an antibody that binds to the estrogen receptor, resulted in nuclear
labeling (Figure 1), whereas control cells incubated with FITC-labeled
IgG showed no staining. In most cells, labeling was entirely confined
to the nucleus. However, occasional cytoplasmic (but not membranous)
staining was also seen.
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Figure 1. Immunolabeling of estrogen receptors in VSMCs (A)
and E304 cells (B). Cells were treated with the FITC-labeled
antiidiotypic antibody 1D5 and visualized by
fluorescence microscopy.10 Control cells were
exposed to FITC-labeled IgG.
Endothelial Cells
Both E2 (0.3 to 300 nmol/L) and DHT (3 to
3000 nmol/L) induced dose-dependent increases in
[3H]thymidine incorporation into DNA (Figure 2). As shown, cells were somewhat more
sensitive to E2 than to DHT (one order of
magnitude). In contrast, progesterone (6 µmol/L) had no effect
on DNA synthesis.
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Figure 2. Effect of E2, DHT, and progesterone
(P) on DNA synthesis assessed by [3H]thymidine
incorporation into DNA in E304 cells and VSMCs. The results are
mean±SEM of 12 incubates from at least 3 different cultures and
expressed as the ratio between the [3H]thymidine
incorporation in the experimental and control vehicle-treated cells
(E/C). *P<0.01, **P<0.001 for the
comparison between treated and untreated cells.
E2 and DHT had a biphasic effect on DNA
synthesis. At a low concentration of E2 (0.3
nmol/L), [3H]thymidine incorporation was
stimulated, whereas higher concentrations of E2
(
30 nmol/L) led to inhibition of DNA synthesis (Figure 2
). Similar
dose-related effects were seen with DHT, ie, stimulation with a low
concentration (3 nmol/L) and inhibition with high concentrations (300
nmol/L). As with endothelial cells,
[3H]thymidine incorporation into DNA was
unaffected by progesterone. ).
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Figure 3. Effects of E2, DHT, and progesterone
(P) in E304 cells or VSMCs on CK-specific activity. Results are
expressed as the ratio between enzyme activity in treated and control
cells (E/C). Details are given in Figure 2 .
Endothelial Cells
PDGF or IGF-1 alone, as well as the combination of either growth
factor with E2 or DHT, increased
[3H]thymidine incorporation in
endothelial cells (Figure 4). At the low concentrations of gonadal
steroids, no synergistic or additive effect was seen between
E2 or DHT and PDGF or IGF-1. However,
[3H]thymidine incorporation was significantly
increased (P<0.05) when E304 cells were exposed to the
higher concentration of E2 or DHT in the presence
of either PDGF or IGF-1 compared with the effects of PDGF or IGF-1
alone (Figures 4 and 5).
E2 increased CK activity (0.3 nmol/L: 30±8%; 30
nmol/L: 90±11%). CK activity was likewise stimulated by PDGF (1
ng/mL: 30±5%; 5 ng/mL: 52±11%), and IGF-1 (12.5 ng/mL: 43±13%; 25
ng/mL: 52±3%). In the presence of E2 (30
nmol/L), both PDGF (5 ng/mL) and IGF-1 (25 ng/mL) elicited even larger
increments in CK (107±10% and 93±2%, respectively). DHT also
increased CK activity (at 3 nmol/L: 38±5%; at 300 nmol/L: 56±4%).
However, the effect of DHT (300 nmol/L) was not modified in the
presence of PDGF (1 or 5 ng/mL, 53±9% and 70±11%, respectively).
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Figure 4. Interaction between E2 and PDGF or
IGF-1 with respect to DNA synthesis in E304 cells or VSMCs. Cells were
incubated with E2 alone (0.3 or 30 nmol/L), PDGF alone (1
or 5 ng/mL), or IGF-1 alone (12.5 or 25 ng/mL) or the combination of
PDGF (5 ng/mL)+E2 (at either 0.3 or 30 nmol/L) or IGF-1 (25
ng/mL)+E2 (30 nmol/L). DNA synthesis is expressed as
outlined in Figure 2 . C indicates control.
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Figure 5. Interaction between DHT and PDGF in the modulation
of DNA synthesis in E304 or VSMCs. Cells were incubated with either DHT
(3 or 300 nmol/L) or PDGF (1 or 5 ng/mL) or with PDGF (5 ng/mL)+DHT (at
either 3 or 300 nmol/L). DNA synthesis is expressed as described in
Figure 4 . C indicates control.
The separate effects of E2 (0.3 and 30
nmol/L), PDGF (1 and 5 ng/mL), or IGF-1 (12.5 and 25 ng/mL) on DNA
synthesis in VSMCs are shown in Figure 4. Stimulation of
[3H]thymidine incorporation was induced by
either of these growth factors and by the low dose of
E2. However, when E2 (30
nmol/L) was present, the stimulatory effects of IGF-1 and PDGF were
entirely inhibited. Furthermore, growth factor–induced DNA synthesis
was suppressed to below basal levels. CK-specific activity was
increased by E2 (0.3 nmol/L: 20±4%; 30 nmol/L:
74±13%), IGF-1 (12.5 ng/mL: 25±7%; 25 ng/mL: 72±9%), or PDGF (1
ng/mL: 44±10%; 5 ng/mL: 133±29%), as well as by the combinations of
E2 (30 nmol/L) with PDGF (43±13% and 52±3% at
the two concentrations applied) or IGF-1 (84±7% and 107±10% at the
two concentrations applied). DHT (at 300 nmol/L but not at 3 nmol/L)
inhibited PDGF-dependent DNA synthesis (Figure 5). In contrast, CK
activity was stimulated by DHT alone (3 nmol/L: 54±11%; 300 nmol/L:
83±9%), PDGF alone (1 ng/mL: 41±12%; 5 ng/mL: 48±9%), or by their
combination (300 nmol/L DHT+PDGF: 68±9% and 122±19%, respectively),
although no additive effect was observed.
Endothelial Cells
In E304 cells, both TAM (30 nmol/L and 3 µmol/L) alone or
RAL (30 nmol/L and 3 µmol/L) alone stimulated DNA synthesis,
whereas TMI was ineffective (Figure 6).
When E2 was also added to antiestrogen-containing
dishes (TAM, RAL, or TMI at 100-fold excess), this agonist-like effect
of antiestrogens on DNA synthesis was not discernible (Figure 6).
Whereas the antiandrogen flutamide was ineffective by itself, it
inhibited the DHT-dependent increase in DNA synthesis (Figure 7).
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Figure 6. Effect of antiestrogens on DNA synthesis in the
absence and presence of E2 in E304 cells and VSMCs. Cells
were incubated with either vehicle or any of the following agents:
E2 (0.3 or 30 nmol/L) or TAM, RAL, and TMI (at 30 nmol/L or
3 µmol/L). Parallel treatments with the antiestrogens (30 nmol/L
or 3 µmol/L) were carried out in the presence of E2
(0.3 or 30 nmol/L), respectively. DNA synthesis was expressed as
described in Figure 4 . C indicates control.
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Figure 7. Effect of the antiandrogen flutamide (Flut) on DNA
synthesis in the absence and presence of DHT in E304 cells and VSMCs.
Cells were incubated with DHT (300 nmol/L), flutamide (10 nmol/L), or
both. DNA synthesis was expressed as described in Figure 4 . C indicates
control.
In VSMCs, the antiestrogen TMI had no effect, whereas both TAM and
RAL mimicked the effect of E2, exhibiting a
stimulatory effect at a low dose (30 nmol/L) and an
inhibitory effect at a higher dose (3 µmol/L).
Notably, in the presence of a low concentration of
E2, the antiestrogens (at 100-fold excess) did
not antagonize the E2-stimulated DNA synthesis.
Likewise, the antiestrogens had no effect on the inhibition of DNA
synthesis exerted by a high concentration of estradiol (Figure 6). In
both cell types, TAM and RAL (but not TMI) enhanced CK activity. In
E304, TAM (3 µmol/L) increased CK by 81±13%, RAL by 66±13%,
and TMI by 1±8%. Similarly, in VSMCs, the same estrogen
antagonists (3 µmol/L) stimulated CK activity (TAM:
85±4%; RAL: 74±11%; and TMI: -2±5%). These
antagonist-induced increases in CK were not apparent in the
presence of E2. Flutamide (10 nmol/L) had no
significant effect on DNA synthesis. However, flutamide blocked both
the increase in DNA synthesis induced by a low concentration of DHT and
the inhibition of [3H]thymidine incorporation
elicited by a high concentration of DHT (Figure 7).
The antiidiotypic antibody 1D5 (8.33
nmol/L), which has estrogen-mimetic activity, elicited a stimulatory
effect on DNA synthesis in E304 cells and an inhibitory
effect in VSMCs (Figure 8). In contrast,
the F(ab')2 fragment of this antibody, which was
inactive by itself, inhibited the effect of E2
and 1D5 in both cell types (Figure 8). In these
cells, E2 (30 nmol/L) caused a 75±13% increase
in CK activity, whereas 1D5 (8.33 nmol/L)
increased CK by 49±6% (compared with a nonsignificant increment of
8±9% observed with IgG). Although the F(ab')2
fragment of 1D5 alone did not modify CK activity
(8±12%), it blocked the E2- and
1D5-induced increments in CK (13±14% and
15±6%, respectively).
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Figure 8. Modulation of DNA synthesis in E304 cells and
VSMCs by the estrogen-mimetic antiidiotypic antibody 1D5
and its proteolytic fragment F(ab')2. Cells were
incubated with E2 (30 nmol/L) alone or with any of the
following proteins: IgG (8.33 nmol/L), 1D5 (8.33
nmol/L), or the F(ab')2 fragment of 1D5 (8.33
nmol/L). In parallel incubates, F(ab')2 (8.33 nmol/L) was
added to wells containing E2 (30 nmol/L) or 1D5
(8.33 nmol/L). DNA synthesis is expressed as described in Figure 2 . C
indicates control.) or CK-specific activity in
either cell type. However, its (Fab') proteolytic fragment, which was
likewise inactive on its own, reversed
E2-dependent suppression of
[3H]thymidine incorporation in VSMCs and
E2-induced stimulation of DNA synthesis in E304
cells (Figure 9). CK-specific activity was enhanced by 30 nmol/L of
E2 (76±12%). E15 (2.5 µg/mL) had no effect on
basal (-11±13%) or E2-stimulated CK activity
(68±12%). Whereas its Fab' fragment (2.5 µg/mL) likewise had no
independent effect (14±7%), it entirely blocked the effect of
E2 (2±4%).
View larger version (41K):
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Figure 9. Modulation of DNA synthesis in E304 cells and
VSMCs by the proteolytic fragment (Fab') of a monoclonal antiestradiol
antibody (E15). Cells were incubated with vehicle or any of the
following: E2 (30 nmol/L), mouse IgG (2.5 µg/mL), E15
(2.5 µg/mL), or the (Fab') fragment of E15 (2.5 µg/mL). In other
incubates, cells were exposed to both E2 (30 nmol/L) and
either E15 (2.5 µg/mL) or (Fab') (2.5 µg/mL). DNA synthesis is
expressed as described in Figure 2 . C indicates control.
Discussion
Top
Abstract
Introduction
Methods
Results
Discussion
References
In the present report, we focus on one aspect of the
interaction of gonadal steroids with the vasculature, ie, the effects
of sex hormones and their antagonists on DNA synthesis in
endothelial and smooth muscle cells derived from human
umbilical vessels. Previous investigations indicated that the
myointimal proliferative response to balloon injury in the rat carotid
artery was inhibited by estrogens but not by androgens, thus suggesting
a differential effect on the response to
injury.14 15 The effects of estradiol on DNA
synthesis in our study are consistent with the concept that
estrogen might influence vascular wall remodeling by inhibition of VSMC
proliferation and increasing the rate of
reendothelialization. The inhibition of DNA synthesis
in VSMCs by higher E2 concentrations is in
accordance with previous reports in porcine and human
cells.16 17 
form of the
estrogen receptor20 raise the possibility that at
least some of the effects reported herein are related to the ß-type
receptor.
Selected Abbreviations and Acronyms
CK
=
creatine kinase
DHT
=
dihydrotestosterone
E2
=
17ß-estradiol
IGF-1
=
insulin-like growth factor-1
PDGF
=
platelet-derived growth factor
RAL
=
raloxifene
TAM
=
tamoxifen
TMI
=
tamoxifen methiodide
VSMC
=
vascular smooth muscle cell
References
Top
Abstract
Introduction
Methods
Results
Discussion
References
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M. R. I. Williams, T. Dawood, S. Ling, A. Dai, R. Lew, K. Myles, J. W. Funder, K. Sudhir, and P. A. Komesaroff Dehydroepiandrosterone Increases Endothelial Cell Proliferation in Vitro and Improves Endothelial Function in Vivo by Mechanisms Independent of Androgen and Estrogen Receptors J. Clin. Endocrinol. Metab., September 1, 2004; 89(9): 4708 - 4715. [Abstract] [Full Text] [PDF]
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S. Ling, A. Dai, R. J. Dilley, M. Jones, E. Simpson, P. A. Komesaroff, and K. Sudhir Endogenous Estrogen Deficiency Reduces Proliferation and Enhances Apoptosis-Related Death in Vascular Smooth Muscle Cells: Insights From the Aromatase-Knockout Mouse Circulation, February 3, 2004; 109(4): 537 - 543. [Abstract] [Full Text] [PDF]
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Y. Li, I. Kishimoto, Y. Saito, M. Harada, K. Kuwahara, T. Izumi, I. Hamanaka, N. Takahashi, R. Kawakami, K. Tanimoto, et al. Androgen Contributes to Gender-Related Cardiac Hypertrophy and Fibrosis in Mice Lacking the Gene Encoding Guanylyl Cyclase-A Endocrinology, February 1, 2004; 145(2): 951 - 958. [Abstract] [Full Text] [PDF]
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 J. M. Orshal and R. A. Khalil Gender, sex hormones, and vascular tone Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2004; 286(2): R233 - R249. [Abstract] [Full Text] [PDF]
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 M. Zeier, B. Dohler, G. Opelz, and E. Ritz The Effect of Donor Gender on Graft Survival J. Am. Soc. Nephrol., October 1, 2002; 13(10): 2570 - 2576. [Abstract] [Full Text] [PDF]
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 S. H. Golden, A. Maguire, J. Ding, J. R. Crouse, J. A. Cauley, H. Zacur, and M. Szklo Endogenous Postmenopausal Hormones and Carotid Atherosclerosis: A Case-Control Study of the Atherosclerosis Risk in Communities Cohort Am. J. Epidemiol., March 1, 2002; 155(5): 437 - 445. [Abstract] [Full Text] [PDF]
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 C. H. Selzman, A. S. Turner, J. S. Gaynor, S. A. Miller, E. Monnet, and A. H. Harken Inhibition of Intimal Hyperplasia Using the Selective Estrogen Receptor Modulator Raloxifene Arch Surg, March 1, 2002; 137(3): 333 - 336. [Abstract] [Full Text] [PDF]
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R. Limor, G. Weisinger, S. Gilad, E. Knoll, O. Sharon, A. Jaffe, F. Kohen, E. Berger, B. Lifschizt-Mercer, and N. Stern A Novel Form of Platelet-Type 12-Lipoxygenase mRNA in Human Vascular Smooth Muscle Cells Hypertension, October 1, 2001; 38(4): 864 - 871. [Abstract] [Full Text] [PDF]
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 S. Ling, G. Deng, H. E. Ives, K. Chatterjee, G. M. Rubanyi, P. A. Komesaroff, and K. Sudhir Estrogen inhibits mechanical strain-induced mitogenesis in human vascular smooth muscle cells via down-regulation of Sp-1 Cardiovasc Res, April 1, 2001; 50(1): 108 - 114. [Abstract] [Full Text] [PDF]
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C. S. Hayward, R. P. Kelly, and P. Collins The roles of gender, the menopause and hormone replacement on cardiovascular function Cardiovasc Res, April 1, 2000; 46(1): 28 - 49. [Full Text] [PDF]
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G.P. Bernini, M. Sgro’, A. Moretti, G.F. Argenio, C.O. Barlascini, R. Cristofani, and A. Salvetti Endogenous Androgens and Carotid Intimal-Medial Thickness in Women J. Clin. Endocrinol. Metab., June 1, 1999; 84(6): 2008 - 2012. [Abstract] [Full Text]
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 R. J. Gonzales and N. L. Kanagy Endothelium-Independent Relaxation of Vascular Smooth Muscle by 17{beta}-Estradiol Journal of Cardiovascular Pharmacology and Therapeutics, January 1, 1999; 4(4): 227 - 234. [Abstract] [PDF]
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 K. J. Scheidegger, B. Cenni, D. Picard, and P. Delafontaine Estradiol Decreases IGF-1 and IGF-1 Receptor Expression in Rat Aortic Smooth Muscle Cells. MECHANISMS FOR ITS ATHEROPROTECTIVE EFFECTS J. Biol. Chem., December 1, 2000; 275(49): 38921 - 38928. [Abstract] [Full Text] [PDF]
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 S. Ling, P. J. Little, M. R. I. Williams, A. Dai, K. Hashimura, J.-P. Liu, P. A. Komesaroff, and K. Sudhir High glucose abolishes the antiproliferative effect of 17beta -estradiol in human vascular smooth muscle cells Am J Physiol Endocrinol Metab, April 1, 2002; 282(4): E746 - E751. [Abstract] [Full Text] [PDF]
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