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,25-Dihydroxyvitamin D3 and 9-cis Retinoic Acid in LNCaP Human Prostate Cancer Cells1
Departments of Medicine (X.-Y.Z., L.H.L., D.F.) and Urology (D.M.P.), Stanford University School of Medicine, Stanford, California 94305
Address all correspondence and requests for reprints to: David Feldman, M.D., Division of Endocrinology, Stanford University Medical Center, Room S-005, Stanford, California 94305-5103.
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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,25-dihydroxyvitamin D3
[1,25-(OH)2D3] inhibits proliferation of
LNCaP cells, an androgen-responsive human prostate cancer cell line.
Also, 1,25-(OH)2D3 increases androgen receptor
(AR) abundance and enhances cellular responses to androgen in these
cells. In the current study, we have investigated the mechanism by
which 1,25-(OH)2D3 regulates AR gene expression
and the involvement of AR in the 1,25-(OH)2D3-
and 9-cis retinoic acid (RA)-mediated growth inhibition of LNCaP cells.
Northern blot analyses demonstrated that the steady-state messenger
RNA (mRNA) level of AR was significantly increased by
1,25-(OH)2D3 in a dose-dependent manner.
Time-course experiments revealed that the increase of AR mRNA by
1,25-(OH)2D3 exhibited delayed kinetics. In
response to 1,25-(OH)2D3, AR mRNA levels were
first detected to rise at 8 h and reached a maximal induction of
10-fold over the untreated control at 48 h; the effect was
sustained at 72 h. Furthermore, the induction of AR mRNA by
1,25-(OH)2D3 was completely abolished by
incubation of cells with cycloheximide, a protein synthesis inhibitor.
1,25-(OH)2D3 was unable to induce expression of
an AR promoter-luciferase reporter. Together, these findings indicate
that the stimulatory effect of 1,25-(OH)2D3 on
AR gene expression is indirect. Western blot analyses showed an
increase of AR protein in 1,25-(OH)2D3-treated
cells. This increased expression of AR was followed by
1,25-(OH)2D3-induced inhibition of growth in
LNCaP cells. Similar to 1,25-(OH)2D3, 9-cis RA
also induced AR mRNA expression, and the effect of both hormones was
additive. Moreover, 1,25-(OH)2D3 and 9-cis RA
acted synergistically to inhibit LNCaP cell growth. These
antiproliferative effects of 1,25-(OH)2D3 and
9-cis RA, alone or in combination, were blocked by the pure AR
antagonist, Casodex. In conclusion, our results demonstrate that growth
inhibition of LNCaP cells by 1,25-(OH)2D3 and
9-cis RA is mediated by an AR-dependent mechanism and preceded by the
induction of AR gene expression. This finding, that differentiating
agents such as vitamin D and A derivatives are potent inducers of AR,
may have clinical implications in the treatment of prostate cancer. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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,25-DIHYDROXYVITAMIN D3
[1,25-(OH)2D3], the active metabolite of
vitamin D, regulates calcium homeostasis in the body by actions in the
intestine, bone, kidney, and parathyroid glands (1, 2). Recently,
1,25-(OH)2D3 has also been shown to have
nonclassical actions. For example, the hormone exerts antiproliferative
and prodifferentiating effects on many cell types, including cells
derived from myeloid, breast, colon, and prostate tissues (3, 4, 5, 6).
Biologic responses of target cells to
1,25-(OH)2D3 are mediated by its nuclear
receptor, the vitamin D receptor (VDR) (7). The VDR belongs to the
steroid/thyroid/retinoid receptor superfamily (1, 2). Numerous studies
indicate that VDR controls target gene transcription by forming a
heterodimeric complex with the retinoid X receptor (RXR), the receptor
for 9-cis retinoic acid (RA), and binding to the vitamin D response
element (VDRE) present in the promoter region of target genes. Our group (8, 9), as well as others (10), have shown that VDRs are present in established human prostate cancer cell lines, as well as primary cultures of normal prostate and cancer cells (11). Moreover, 1,25-(OH)2D3 and its analogs significantly inhibit cellular proliferation of prostate cancer cells, including LNCaP (8, 9, 12, 13, 14, 15, 16, 17, 18, 19, 20). LNCaP cells express both the VDR and the androgen receptor (AR). Our recent studies (21) and those of others (15, 22) have demonstrated that cross-talk between 1,25-(OH)2D3 and androgens exists and that the antiproliferative actions of 1,25-(OH)2D3 in LNCaP cells are androgen-dependent. Blutt et al. (17) have shown that 9-cis RA acts synergistically with 1,25-(OH)2D3 to inhibit LNCaP cell growth.
Because cellular responsiveness to androgen depends on AR abundance, in the present study, we have analyzed the ability of 1,25-(OH)2D3 and 9-cis RA to regulate the level of AR gene expression in these cells. We found that 1,25-(OH)2D3 increased the levels of AR messenger RNA (mRNA) and AR protein in a concentration- and time-dependent manner. Such regulatory effects of 1,25-(OH)2D3 on AR gene expression required de novo protein synthesis. Furthermore, the stimulatory effect of 1,25-(OH)2D3 on AR mRNA was also enhanced by 9-cis RA. Because it has been reported that the antiproliferative effects of 1,25-(OH)2D3 on LNCaP cells can be synergistically enhanced by the addition of 9-cis RA (17), we examined the involvement of AR in the antiproliferative action of 9-cis RA, as well as 1,25-(OH)2D3. Using the pure AR antagonist, Casodex, we demonstrated that AR blockade prevented the growth inhibitory activity of both 1,25-(OH)2D3 and 9-cis RA. In contrast, Casodex did not affect the antiproliferative activity of dibutyrl cAMP, a well-known up-regulator of AR in LNCaP cells (23). Our studies demonstrate that both 1,25-(OH)2D3 and 9-cis RA up-regulate AR mRNA levels in LNCaP cells and that growth inhibition mediated by 1,25-(OH)2D3 and 9-cis RA requires the action of AR.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Cell culture and hormone treatment
The LNCaP human prostate carcinoma cell line was obtained from
the American Type Culture Collection (Rockville, MD).
Cells were routinely cultured in RPMI-1640 medium supplemented
with 5% FBS and antibiotics (FBS medium), at 37 C in a humidified
atmosphere of 5% CO2. For experiments, LNCaP cells were
trypsinized and seeded at an appropriate density, and hormonal
treatments were initiated, the next day, in FBS medium or in RPMI-1640
medium supplemented with 5% CSS and antibiotics (CSS medium).
Hormone stocks [1,25-(OH)2D3, 9-cis RA, and Casodex] were prepared in 100% ethanol, at a concentration 1000-fold higher than the working concentrations. Fresh culture media were premixed with hormone stock and then added to triplicate wells. Media and hormone were replenished every 2 days. Controls received ethanol vehicle at a concentration equal to that in hormone-treated cells.
Assay of cell proliferation
Cell proliferation was assessed by measurement of attained cell
mass using an assay of DNA content. As previously described (21), LNCaP
cells were seeded in six-well tissue culture plates (Becton Dickinson and Co., Lincoln Park, NJ), at a density of 50,000
cells per well, in 3 ml RPMI-1640 containing 5% FBS. After incubation
for 24 h, the medium was replaced with fresh medium containing 5%
FBS (FBS medium). Cells were treated with vehicle (ethanol, final
concentration 0.1%), 1,25-(OH)2D3, 9-cis RA,
dibutyrl cAMP, or Casodex. On the sixth day, cell monolayers were
processed for DNA assay using the method of Burton (24). DNA content of
each treatment was derived from the mean value of triplicate wells in
an experiment. Each experiment was repeated three times.
Western blot analysis
Cells were treated with ethanol or
1,25-(OH)2D3 (10 nM) in RPMI-1640
medium containing 5% CSS (CSS medium) for 2 days. They were
harvested, and sonicated extracts were prepared as described. Aliquots
of 100 µg protein were heated in SDS sample buffer at 95 C, for 5
min, before electrophoresis in an 8% SDS-polyacrylamide gel. After
electrophoresis, the gels were transferred and processed as previously
described (25). After transfer, the blots were incubated with anti-AR
monoclonal antibody F39.4 (1:100 dilution) for 1 h, at room
temperature, with gentle shaking. The blots were washed and then
incubated with a horseradish peroxidase-conjugated rabbit antimouse IgG
(1:1000 dilution) for 1 h at room temperature. Blots were rewashed
and developed with the Enhanced Chemiluminesence (ECL) System
system, according to the manufacturer’s instructions (Amersham
Chemical Co.).
Steroid receptor ligand-binding assay
LNCaP cells were seeded at a density of 150,000 cells per 100-mm
dish in 10-ml medium containing 5% FBS or 5% CSS. At the end of the
6-day incubation with hormone (at concentrations of 0, 1, and 10
nM), cell monolayers were harvested, and high-salt nuclear
extracts were made as previously described (21). Protein concentration
of the extract was determined (26). In a typical binding experiment,
200 µl soluble extract (1–2 mg protein/ml) were incubated with 10
nM concentration of
[3H]-5-dihydrotestosterone (DHT) for 16–20 h
at 4 C. Bound and free hormone were separated by hydroxylapatite (21).
Specific binding was calculated by subtracting nonspecific binding
(obtained in the presence of a 250-fold excess of radioinert DHT) from
the total binding (measured in the absence of radioinert steroid). Data
were expressed as femtomoles [3H]-DHT bound per milligram
protein.
Northern blot analysis
Northern blot analysis was performed as previously described (8, 11). Briefly, semiconfluent LNCaP cells were treated with graded
concentrations of 1,25-(OH)2D3, or 5
mM dibutyrl cAMP, or 9-cis RA in FBS medium and in CSS
medium for 24 h before isolation of total RNA. Ten micrograms of
total RNA were denatured, fractionated by electrophoresis, and
transferred to Hybond-N nylon membrane (Amersham), as previously
described (8, 11). The bound RNA was immobilized by UV cross-linking
and then hybridized with a random primed [32P]-labeled
0.8-kb HindIII-BamHI fragment of the human AR
cDNA at 60 C. To control for RNA sample loading and transfer, Northern
blots were also hybridized with a [32P]-labeled 0.9-kb
EcoRI fragment of the human cDNA for the ribosomal protein
gene L7 (8, 11). The silver grain pixel intensity of each AR and L7
band was scanned by a densitometer, and the data were integrated by
scanner software and indexed to the corresponding levels of L7
mRNA.
AR promoter-luciferase reporter gene assay
LNCaP cells were seeded at 3 x 106
cells/dish in 60-mm tissue culture dishes (Corning, Inc.,
Corning, NY) in RPMI-1640 medium containing 5% FCS and antibiotics. A
6-kb promoter-luciferase reporter was transfected using a
calcium-phosphate method (23). Each transfection contained 1 µg
pAR-LUC DNA (Drs. G. Mora and D. Tindall, personal communication) and
0.1 µg pSV-Renilla DNA. The control plasmid pSV-Renilla was used to
monitor transfection efficiency. Cells were harvested after 32 h
of incubation with tested compounds at 37 C. Luciferase activity was
employed to measure induction using Promega Corp.
(Madison, WI) dual luciferase assay system on luminometer TD-20 (Turner
Design, Sunnyvale, CA). The results were expressed as the ratio of
luciferase activity to Renilla activity.
Statistical analysis
ANOVA was used to assess the statistical significance of the
difference. P < 0.05 was considered significant.
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Results |
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Dose response effect of 1,25-(OH)2D3 on AR
mRNA
The effect of 1,25-(OH)2D3 on
steady-state AR mRNA levels was assessed by Northern blot analysis. We
have used two culture conditions (FBS medium and CSS medium) in this
set of experiments and have observed similar results. As shown in Fig. 1
, LNCaP cells express a major transcript
of AR at 11 kb. In Fig. 1A, the cells were treated in CSS medium for
24 h with increasing concentrations of
1,25-(OH)2D3 (0–100 nM), and AR
mRNA transcripts increased in a dose-dependent manner. The increased AR
mRNA levels became evident with a concentration of
1,25-(OH)2D3 at 1 nM (lane 3).
Increasing the 1,25-(OH)2D3 concentration
caused further induction of AR mRNA (lanes 4–5). The levels of AR mRNA
were quantitatively determined by densitometric scanning of the
autoradiographs, with correction for the L7 mRNA signal (Fig. 1B). At
100 nM of 1,25-(OH)2D3, more than
5-fold up-regulation of AR mRNA was detected (lane 5). When we carried
out the experiment using FBS medium (Figs. 1, C and D), we also
detected a significant up-regulation of AR mRNA in LNCaP cells in
response to 1,25-(OH)2D3 treatment for 24
h. Hence, 1,25-(OH)2D3 increased AR mRNA
expression in LNCaP cells in a dose-dependent manner in either CSS
medium or FBS medium.
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, time-course experiments
using CSS medium revealed that addition of 10 nM
1,25-(OH)2D3 to LNCaP cells increased AR mRNA
levels by 8 h. The AR mRNA levels peaked at 48 h in the
treated cells, with a 10-fold higher level, compared with the untreated
cells at the concurrent time point, and this inductive effect of
1,25-(OH)2D3 was sustained at 72 h. No
change in AR mRNA could be detected at 4 h, suggesting a delayed
primary response of AR gene expression to
1,25-(OH)2D3.
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). The major species of AR in
LNCaP cells was detected as a single band, at 108 kDa, by monoclonal
antibody F39.4. There was no detectable increase in AR protein levels
after 24 h treatment (data not shown), but levels rose
approximately 4-fold in cells treated with 10 nM
1,25-(OH)2D3 for 48 h. As seen for AR mRNA
levels (Fig. 1
), a detectable increase in AR protein was evident with 1
nM 1,25-(OH)2D3.
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Requirement of new protein synthesis for
1,25-(OH)2D3 regulation of AR
To determine whether 1,25-(OH)2D3 affected
AR mRNA levels via a direct mechanism, LNCaP cells in CSS medium were
treated for 24 h with 1,25-(OH)2D3 in the
presence of the protein synthesis inhibitor cycloheximide (CHX) at
various doses (0, 2, 5, and 10 µg/ml). As shown in Fig. 4, CHX blocked the
1,25-(OH)2D3-induced increase in AR mRNA
levels, such that in the presence of CHX and
1,25-(OH)2D3 (lane 3), AR mRNA levels were no
higher than those in untreated cells (lane 1). The extent of blockade
depended upon the concentration of CHX included in the media (lanes
3–5). Moreover, the effect of CHX could be detected at either 16
h (lane 6) or 24 h (lane 4).
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Enhancement of 1,25-(OH)2D3-mediated
up-regulation of AR by 9-cis RA
It recently has been reported that
1,25-(OH)2D3 acts synergistically with 9-cis RA
to inhibit LNCaP cell proliferation (17). We therefore investigated the
effect of 9-cis RA on 1,25-(OH)2D3 regulation
of AR mRNA. Both culture conditions (FBS medium and CSS medium) gave
similar results. As shown in Fig. 5, 1,25-(OH)2D3, at a dose of 10 nM,
induced a 5-fold increase in AR mRNA levels (lane 1) over the control
at 24 h (lane 2). LNCaP cells, treated with 100 nM
9-cis RA for 24 h, expressed 3-fold more AR mRNA (lane 3) than the
untreated cells (lane 2). Combination treatment of
1,25-(OH)2D3 and 9-cis RA gave a more than
8-fold induction of AR mRNA (lane 4). Thus, although
1,25-(OH)2D3 was more effective than 9-cis RA
in up-regulating AR mRNA, both hormones acted additively to increase AR
gene expression in LNCaP cells.
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, 10 nM
1,25-(OH)2D3 inhibited LNCaP cell growth 50%,
whereas 100 nM 9-cis RA only reduced proliferation by 10%.
However, combination treatment with
1,25-(OH)2D3 and 9-cis RA caused 80% growth
inhibition. Casodex was used to determine whether the 9-cis RA action
was also AR-dependent. In the presence of Casodex, neither
1,25-(OH)2D3 nor 9-cis RA inhibited cell growth
individually or in combination (Fig. 6A). On the other hand, dibutyrl
cAMP, a known up-regulator of AR in LNCaP cells, inhibited cell
proliferation in a dose-dependent manner (Fig. 6B). With maximal growth
inhibition of 90% occurring at a dose of 5 mM dibutyrl
cAMP, addition of Casodex, however, did not block this effect (Fig. 6B). These data imply that the actions of
1,25-(OH)2D3 and 9-cis RA on LNCaP cell growth
are both AR-dependent. In contrast, cAMP, although an inducer of AR
(23), inhibits LNCaP cell proliferation by an AR-independent
mechanism.
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depicts the possible events in the
1,25-(OH)2D3 signaling pathway in these cells.
1,25-(OH)2D3 binds to the VDR and activates the
receptor. The activated VDR controls target gene transcription by
forming a heterodimer with the partner RXR and binding to the VDRE in
the promoter region of a target gene. A
1,25-(OH)2D3 target gene (or genes) encodes
protein(s) X, mediators of the up-regulation of AR mRNA in response to
1,25-(OH)2D3. The production of protein(s) X is
CHX-sensitive. Both 1,25-(OH)2D3 and 9-cis RA,
individually or in combination, induce AR mRNA expression. The
increased AR mRNA causes an increase in AR protein levels, which
mediates the action of androgens on LNCaP cell growth. As we reported
previously (23), either 1,25-(OH)2D3 or DHT was
growth inhibitory on LNCaP when cells were cultured in FBS-containing
medium. The androgen action is blocked by the AR antagonist, Casodex.
Although both the AR mRNA and the AR protein are also induced in CSS
medium, in the absence of androgens,
1,25-(OH)2D3 does not exhibit an
antiproliferative effect on LNCaP cells in this culture system
(21).
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Nonetheless, our finding that androgen mediates the antiproliferative activity of 1,25-(OH)2D3 in LNCaP cells is not the situation in all prostate cancer cells. 1,25-(OH)2D3 inhibits the growth of AR-negative prostate cancer cell line PC-3, as well as primary cultures of human prostate cells. In contrast to LNCaP cells, mechanisms other than androgen signaling are responsible for the growth inhibitory effect of 1,25-(OH)2D3 on these cells.
It is of interest to consider whether increasing the abundance of a steroid receptor, such as the AR, will cause an increased amplitude of response, i.e. antiproliferation. Although it has been well demonstrated that the level of receptors in LNCaP does not necessarily predict the ligand potency of a hormonal response (8, 14, 19, 27), it is clear that the presence of a receptor is essential for a response (1, 2, 13, 14, 28). In a given cell, in the presence of a constant level of hormone, up-regulation of the receptor does cause an enhanced response, whereas down-regulation of the receptor diminishes the response (13, 14, 28, 29, 30). Therefore, we believe that up-regulation of AR, in these studies, is the mechanism of the enhanced antiproliferative effect.
The expression of the AR gene has been found to be induced by a number of agents in several systems, such as the rat ventral prostate (31), and in LNCaP human prostate cancer cells (32, 33). Growth factors such as FSH, EGF, and TGF-ß regulate AR gene expression (34, 35). Activators of protein kinase A, such as forskolin and dibutyrl cAMP, are the known up-regulators of AR in LNCaP cells (23). The induction of AR by these reagents was not detected in the two other commonly studied prostate cancer cell lines, PC-3 and DU 145, which do not express basal levels of AR mRNA (36).
1,25-(OH)2D3 is the most potent inducer of AR in LNCaP cells, among the three agents that we tested. Consistent with the reported data (23), we found that treatment of LNCaP cells with dibutyrl cAMP for 24 h caused a 2-fold increase in AR mRNA levels (data not shown). In the same experiment, we observed an increase of 5-fold in AR mRNA, with 1,25-(OH)2D3 at 10 nM. 9-cis RA induced 3-fold induction of AR mRNA. It has been reported that dibutyrl cAMP increases AR gene transcription via the cAMP-response elements present in the 2.3-kb promoter region of the human AR gene (23). In contrast, the same promoter region of the AR gene seems to lack a VDRE and an RXRE. Computer searching of the 2.3-kb promoter region failed to identify a consensus sequence for these regulatory elements. Moreover, the luciferase reporter construct, driven by a 6-kb promoter region of the human AR gene, did not respond to 1,25-(OH)2D3 or 9-cis RA but did respond to dibutyrl cAMP.
An indirect mechanism for 1,25-(OH)2D3 action
to induce AR was supported by several findings taken together: the
delayed time of AR mRNA rise in time-course experiments (Fig. 2), the
CHX studies (Fig. 3), and the failure of the promoter to respond to
1,25-(OH)2D3 (data not shown). We refer to the
indirect, CHX-inhibited mediator(s) of
1,25-(OH)2D3 action to up-regulate AR as
protein(s) X. We surmise that, in the presence of CHX,
1,25-(OH)2D3 was unable to induce protein(s) X,
and as a consequence, 1,25-(OH)2D3 failed to
up-regulate AR mRNA (Fig. 4). It is interesting to speculate on the
nature of protein(s) X. Protein(s) X may be related to the chaperon
proteins, given the fact that several chaperons have been identified in
the regulation of steroid receptors (37). Further studies are needed to
elucidate this mechanism.
We did not detect AR up-regulation by 1,25-(OH)2D3 in two human breast cancer cells, either MCF-7 or T47D (unpublished data). Both MCF-7 and T47D cells express the VDR, as well as the AR. However, the levels of AR protein did not change in both cell lines when treated with 1,25-(OH)2D3. Therefore, induction of protein(s) X by 1,25-(OH)2D3 may be tissue-specific. At present, it is difficult to examine this point because of the limited number of human prostate cancer cells that exhibit the AR. We have, thus far, been unable to induce AR in cells that lack the AR, including primary cultures of prostate cancer cells and established cell lines PC-3 or DU 145. To determine whether AR induction by 1,25-(OH)2D3 is LNCaP cell-specific, we hope to study other AR-positive human prostate cancer cell lines as they become available.
The action of androgens to inhibit proliferation of cultured prostate cancer cells is an interesting finding. We and others (21, 38) showed that LNCaP cells exhibit a biphasic growth response to DHT in charcoal-stripped serum-containing medium, with a growth stimulatory effect at a low concentration (less than 1 nM) and an inhibitory effect at a high concentration (greater than 1 nM). The levels of AR protein in LNCaP cells determine the concentration of DHT at which the stimulatory effect crosses over to an inhibitory effect. In other words, the stimulatory effect is favored at low abundance of AR, and an inhibitory effect at high abundance of AR (21). Liao and co-workers (39, 40, 41) found that high-passage LNCaP cells in an androgen-depleted medium express 10- to 20-fold higher AR levels and are growth inhibited by androgens in vitro and in an in vivo mouse model. Moreover, they demonstrated that G1 arrest of the high AR-expressing cells by androgen is caused by the induction of p27kip1, which in turn inhibits Cdk2, a factor critical for cell cycle progression and proliferation (41). There are two additional examples to document the role of AR in the inhibition of growth of prostate cancer cells. Yuan et al. (42) have reported that PC-3 cells, stably transfected with the human AR cDNA, were growth inhibited by androgen. Recently, Zhau et al. (43) have established an androgen-repressed human prostate cancer cell line (ARCaP) derived from the ascites fluid of a patient with advanced metastatic disease, which is growth inhibited by androgens. Cumulatively, these findings support the hypothesis that higher levels of AR in cultured prostate cancer cells cause increased sensitivity to growth inhibition.
In summary, we have shown that the hormonally active forms of vitamin D and vitamin A are potent inducers of AR in LNCaP cells. Both 1,25-(OH)2D3 and 9-cis RA act in synergy to inhibit cell proliferation; moreover, their antiproliferative actions can be blocked by the AR antagonist, Casodex. In conclusion, our study provides direct evidence for an important role of the AR in mediating the growth inhibitory actions of 1,25-(OH)2D3 and 9-cis RA in LNCaP cells. More importantly, the newly discovered AR-inducing property of both vitamins A and D suggests a possible application of these potential chemo-preventive agents in increasing androgen sensitivity of prostate cancer cells. An understanding of the mechanisms of AR gene regulation may be of great importance in efforts to restore androgen responsiveness to the patients with androgen-independent prostate cancer, because this type of cancer is commonly unresponsive to most conventional therapies.
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Acknowledgments |
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Footnotes |
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Received August 20, 1998.
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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,25-dihydroxyvitamin D3. Cancer Res 52:515–520,25-dihydroxyvitamin D3 in
seven human prostatic carcinoma cell lines. Clin Cancer Res 1:997–1003[Abstract]
,25-dihydroxyvitamin D3 in human prostate
cancer cell line LNCaP involves reduction of cyclin-dependent kinase 2
activity and persistent G1 accumulation. Endocrinology 139:1197–1207This article has been cited by other articles:
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J. L. Martin and S. L. Pattison Insulin-Like Growth Factor Binding Protein-3 Is Regulated by Dihydrotestosterone and Stimulates Deoxyribonucleic Acid Synthesis and Cell Proliferation in LNCaP Prostate Carcinoma Cells Endocrinology, July 1, 2000; 141(7): 2401 - 2409. [Abstract] [Full Text] [PDF]
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X.-Y. Zhao, D. M. Peehl, N. M. Navone, and D. Feldman 1{alpha},25-Dihydroxyvitamin D3 Inhibits Prostate Cancer Cell Growth by Androgen-Dependent and Androgen-Independent Mechanisms Endocrinology, July 1, 2000; 141(7): 2548 - 2556. [Abstract] [Full Text] [PDF]
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 T. J. Schrader and G. M. Cooke Examination of Selected Food Additives and Organochlorine Food Contaminants for Androgenic Activity in Vitro Toxicol. Sci., February 1, 2000; 53(2): 278 - 288. [Abstract] [Full Text] [PDF]
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D. Feldman, X.-Y. Zhao, and A. V. Krishnan Editorial/Mini-Review: Vitamin D and Prostate Cancer Endocrinology, January 1, 2000; 141(1): 5 - 9. [Full Text] [PDF]
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 M. Guzey, S. Takayama, and J. C. Reed BAG1L Enhances Trans-activation Function of the Vitamin D Receptor J. Biol. Chem., December 22, 2000; 275(52): 40749 - 40756. [Abstract] [Full Text] [PDF]
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H.-K. Lin, S. Yeh, H.-Y. Kang, and C. Chang Akt suppresses androgen-induced apoptosis by phosphorylating and inhibiting androgen receptor PNAS, June 19, 2001; 98(13): 7200 - 7205. [Abstract] [Full Text] [PDF]
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