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Obstetrics & Gynecology 2007;110:146-154
© 2007 by The American College of Obstetricians and Gynecologists
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ORIGINAL RESEARCH

Endometrial Expression of Cyr61

A Marker of Estrogenic Activity in Normal and Abnormal Endometrium

Shannon D. MacLaughlan, MD1,2, Wilder A. Palomino, MD1, Bilan Mo, MS1, Terrence D. Lewis3, Ruth A. Lininger, MD3 and Bruce A. Lessey, MD, PhD1

From the 1 Warren Alpert Medical School of Brown University, Providence, Rhode Island; 2 University Medical Group, Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Greenville Hospital System, Greenville, South Carolina; and 3 Department of Pathology and Laboratory Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina.


   ABSTRACT
TOP
ABSTRACT
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
OBJECTIVE: To compare the expression of Cyr61 in normal cycling endometrium with endometrium from women with polycystic ovarian syndrome (PCOS) and endometrial hyperplasia and adenocarcinoma.

METHODS: This is a retrospective study of 59 samples of normal and abnormal endometrium. Endometrial biopsies were obtained from normal fertile controls throughout the menstrual cycle and compared with endometrium from ovulatory and anovulatory women with PCOS and complex endometrial hyperplasia and endometrioid adenocarcinoma. Cyr61 expression was evaluated by using immunohistochemistry and reverse transcription PCR for Cyr61, estrogen receptor (ER)-{alpha}, a marker of cell proliferation (Ki67), and another marker of early estrogen action, cFos. Regulation of Cyr61 protein was studied in a steroid-responsive endometrial carcinoma cell line, ECC1.

RESULTS: Cyr61 protein was regulated by estrogen. In normal endometrium, Cyr61 was highest in the proliferative phase and lowest in the normal midsecretory phase. In contrast, elevated levels of Cyr61, ER-{alpha}, Ki67, and cFos were all found in the midsecretory endometrium of ovulatory PCOS patients, endometrial cancer patients, and hyperplasia patients.

CONCLUSION: Cyr61 is overexpressed in PCOS endometrium, reflecting a heightened responsiveness to estrogen. As a unique marker of estrogen action, Cyr61 may be an early biomarker for the development of hyperplasia or adenocarcinoma in this group of women.

LEVEL OF EVIDENCE: II

Endometrial adenocarcinoma is a disorder of cell proliferation and thought to arise as an estrogen-dependent cancer in many cases. Women with polycystic ovarian syndrome have been described as a group that is prone to the development of endometrial hyperplasia and cancer1 Cysteine-rich 61 (Cyr61), is an immediate early gene encoded on chromosome 1.2 It encodes a protein that is a member of the CCN protein family and is an integrin-binding, angiogenic factor that also promotes cell migration and adhesion.3Cyr61 protein is a regulator of apoptosis and associated with tumorigenesis, with disparate roles in different cell types. As a tumor suppressor in small-cell lung cancer, it functions by up-regulating p53.4,5Cyr61 expression is down-regulated in prostate6 and thyroid cancers,7 whereas Cyr61 expression is elevated and associated with poor prognosis in glioblastoma multiforma tumors.8

Cyr61 expression has also been reported in gynecologic disorders, including uterine fibroids and endometriosis and in breast cancer. Elevated levels of Cyr61 protein has been described in uterine leiomyomata compared with normal myometrium.9 Aberrant expression of Cyr61 has also been described in human endometriosis as a marker of cell proliferation and present in endometriosis in primate models of this disorder.10,11 In human breast cancer, Cyr61 is over-expressed in tumor biopsies and metastases. Interestingly, the presence of Cyr61 is associated with more aggressive, estrogen receptor (ER)-negative cell types, and it appears to confer resistance to chemotherapy-induced apoptosis through an integrin-mediated mechanism. The only study on Cyr61 expression in an endometrial cancer cell line found that Cyr61 appeared to suppress the growth rate of endometrial cancer cells.18 Interference with Cyr61 expression in the Ishikawa cells resulted in increased growth of this cell line. Little information is available on the expression of Cyr61 in the endometrium of women with polycystic ovarian syndrome (PCOS) or endometrial hyperplasia or adenocarcinoma.

Like cFos, Cyr61 is rapidly upregulated by estrogen within minutes of stimulation. Transcripts of Cyr61 RNA have been shown to be up-regulated by 17ß-estradiol in ovariectomized rats and down-regulated by the antiestrogen ZK191703.19Cyr61 has been localized in the glandular epithelium of human endometrium, with increased expression in the proliferative phase, and elevated in women with endometriosis.10 Recent studies in our laboratory show that Cyr61 is regulated through a G-protein–coupled estrogen receptor, GPR30, rather than the traditional estrogen receptor (Young SL, Scotchie JG, Palomino WA, Lessey BA. Expression, regulation, and possible function of the alternative estrogen receptor, GPR30, in human endometrial cells [abstract]. Reprod Sci 2007;14 suppl:204A). Because both Cyr61 and GPR30 are associated with poor prognosis in various cancers, the investigation of Cyr61 as a biomarker of alternative estrogen signaling will likely be important. The purpose of this study was to examine the expression patterns of Cyr61 in women with PCOS, a group who are thought to be at high risk for development of endometrial neoplasia and to compare the levels of expression in the endometrium of fertile women and women with endometrial hyperplasia and cancer


   MATERIALS AND METHODS
TOP
ABSTRACT
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Endometrial biopsies were obtained as part of institutional review board–approved protocols (University of North Carolina, Chapel Hill, North Carolina, and Greenville Hospital System, Greenville, South Carolina). Proliferative and secretory samples from five normal, fertile women were obtained at the time of surgery for tubal ligation and some samples (n=5) were obtained from normal fertile volunteers in luteinizing hormone (LH)-timed cycles. Secretory phase samples from fertile and infertile women were also obtained based on the time of the urinary LH surge and classified as early secretory (urinary LH surge plus 1–5), midsecretory (LH surge plus 6–10), and late secretory (LH surge plus 11–14). Six samples were obtained from anovulatory PCOS patients, and six from PCOS patients induced to ovulate with clomiphene citrate. All PCOS patients met the criteria for PCOS based on the Consensus meeting in Rotterdam,20 and all had signs or laboratory evidence of hyperandrogenism. Complex endometrial hyperplasia with (n=5) and without (n=5) atypia were evaluated along with 15 samples of endometriod adenocarcinoma of varying grades. Demographic characteristics in terms of age of the patient population is shown in Table 1. All samples were placed in 10% buffered formalin and processed into paraffin blocks. Serial 5-mm sections were obtained and processed for immunohistochemistry. Additional samples were snap frozen on liquid nitrogen, and RNA was extracted for reverse transcriptase polymerase chain reaction (PCR), including four additional samples of adenocarcinoma provided by the Gynecologic Oncology Group.


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  		Table 1. Demographics of Patient Population

 

Cyr61 expression was evaluated by immunohistochemistry in sections of endometrial biopsies by using a polyclonal antibody directed against human Cyr61 (generously provided by Lester F. Lau, University of Illinois at Chicago, Chicago, Illinois).21 This antibody was serially diluted in a solution of phosphate-buffered saline containing 1% normal goat serum and 0.1% sodium azide to optimize the appropriate concentrations to achieve maximum sensitivity and specificity. Tissue sections were incubated with primary antibody at 4ºC overnight at 1:150 final concentration. Negative control sections were treated with nonimmune serum diluted in the same manner.

Sections were deparaffinized in toluene and rehydrated with serially graded concentrations of ethanol. Antigen retrieval was achieved by heating sections in 750-W microwave oven at 80% power in 0.01 M citrate buffer pretreatment. After a phosphate-buffered saline rinse, endogenous peroxidase was quenched with a 30-minute incubation with 0.3% H2O2 in absolute ethanol and incubated with blocking serum for 15 minutes at room temperature (1:100 dilution of nonimmune goat serum). After primary antibody incubation, sections were washed twice with phosphate-buffered saline, followed by treatment with 2% normal goat serum for an additional 30 minutes. Subsequently, sections were washed with phosphate-buffered saline and incubated with biotin-SP-conjugated goat antirabbit immunoglobulin (Ig)G (Jackson ImmunoResearch Labs, West Grove, PA) at a dilution of 1:100 for 30 minutes at room temperature. After rinsing with phosphate-buffered saline, the immunoreactive antigen was visualized by using avidin-biotin peroxidase complex (Vectastain Elite ABC kit, Vector Laboratories Inc, Burlingame, CA) and 3,3 –diaminobenzidine as chromogen. Slides were counterstained with Mayer's hematoxylin blue/toluidine blue followed by dehydration in a graded series of ethanols, cleared in xylene, and mounted with Permount (Fisher Scientific, Fair Lawn, NJ). The resulting staining was evaluated on a Nikon (Tokyo, Japan) microscope by two blinded observers. For this analysis, staining intensity was assigned by using a semiquantitative histologic score (HSCORE) as previously described.22 The HSCORE was calculated with the following equation: HSCORE={Sigma} Pi (i+1), where i=intensity of staining with a value of 1, 2, or 3, (weak, moderate, or strong, respectively) and Pi is the percentage of stained epithelial cells for each intensity, varying from 0% to 100%.

Unless otherwise stated, all reagents were obtained from Sigma Inc (St. Louis, MO). Endometrial carcinoma cell line (ECC1), a hormone-responsive endometrial cell line, was cultured in phenol red-free media (Dulbecco modified eagle's medium/F12) supplemented with 5% charcoal-stripped fetal calf serum (Hi-Clone, Logan, UT) for 2 days before hormone treatment at 37ºC in 95% air, 5% CO2. Cells were then treated with no hormone (control) or the synthetic estrogen diethylstilbestrol (DES; 10-8M) plus or minus equimolar concentrations of the antiestrogen ICI 182,780. Cells were treated for 30 minutes, 1, 2, 4, 8, and 24 hours. Approximately 50–100 mg of cells were homogenized on ice in 1 mL of tissue homogenate buffer (20 mM Tris-HCl [pH 7.4], 150 mM NaCl, 1 mM ethylenediaminetetraacetic acid [EDTA, pH 8.0], 0.25% sodium deoxycholate, 1% Igepal CA630) containing protease inhibitors (1 mM phenylmethylsulfonylfluoride, 50 mM NaF, 1 mcg/mL pep stain, 1 mcg/mL aprotinin, 1 mcg/mL leupeptin, and 1 mM sodium orthovanadate). Tissue homogenates were incubated on ice for 30 minutes and then were cleared by centrifugation at 16,000g for 15 minutes at 4°C. The supernatant was collected and the protein concentration measured with the Bradford protein concentration assay kit (Bio-Rad, Hercules, CA). Sixty micrograms of protein were added per lane, resolved on 4–15% sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE; Biorad) and transferred to polyvinylidene fluoride membranes. After blocking nonspecific binding in 5% skim milk containing 0.1% Tween-20 (vol/vol), blots were incubated with rabbit antihuman Cyr61 polyclonal antibody at 4°C overnight. Bands were detected by incubating the membrane with peroxidase-conjugated goat antirabbit IgG for 1 hour at room temperature. Thereafter, membranes were incubated in Amersham enhanced chemiluminescence reagents for exactly 1 minute, exposed to film, and then developed for documentation. Standards molecular weight markers were used on each gel (Cell Signaling, Danvers, MA).

Total cellular RNA from the human endometrial cancer cell lines was extracted with a TRIzol reagent (Invitrogen, Carlsbad, CA) according to the manufacturer's instructions. The reverse transcriptase PCR was performed with AccessQuick reverse transcriptase PCR system on a GeneAmp PCR system 9700 (PE Applied Biosystems, Foster City, CA). The oligomer used for reverse transcriptase PCR specific to Cyr61 were as follows: forward 5'-ACT TCA TGG TCC CAG TGC TC-3' and reverse 5'-AAA TCC GGG TTT CTT TCA CA-3'. The routine reverse transcriptase PCR program was two pre-PCR cycles of 45 minutes at 48°C and 5 minutes at 94°C, and 28 cycles of PCR for amplification of the target gene. Expected size of the Cyr61 product was 118 bp. All PCR products from a single experiment were run on a 2% agarose gel and stained with ethidium bromide and photographed on a Biorad Gel Doc 2000.

Comparisons between HSCOREs and age between groups was made by using analysis of variance with Scheffe correction for multiple comparisons. Statistical significance was set at P<.05 for the 95th percentile confidence interval.


   RESULTS
TOP
ABSTRACT
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
To examine the regulation of Cyr61 in a hormone-responsive cell line, we treated ECC1 cells with a synthetic estrogen (DES) or DES plus a potent antiestrogen ICI 182,780 for 0.5–24 hours. As shown in Figure 1, Cyr61 is rapidly induced by estrogen, reaching maximal expression by 4 hours. This rise in Cyr61 is initially blocked by the antiestrogen ICI, with peak activity at 30 minutes to 2 hours.


Figure 125
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  		Fig. 1. Western blot time course for Cyr61 in cells in the endometrial carcinoma cell line (ECC1) treated with diethylstilbestrol (DES) alone or in the presence of the antiestrogen ICI 182,780 (DES+ICI) for 0–24 hours. ß-actin (b-actin) served as a control for loading, and the absorbance of Cyr61/ß-actin was plotted for comparison. Note that Cyr61 expression increased acutely by 4 hours in response to the synthetic estrogen, DES. The effect of ICI was apparent within 15 minutes.

MacLaughlan. Cyr61 in Normal and Abnormal Endometrium. Obstet Gynecol 2007.

 

An examination of endometrial Cyr61 protein and mRNA throughout the menstrual cycle was undertaken by using the techniques of immunohistochemistry and reverse transcriptase PCR. As shown in Figure 2, changes in the expression of mRNA for Cyr61 from samples from normal women show that expression patterns are highest in the proliferative phase and reduced during the time of peak serum progesterone in the midsecretory phase (Fig. 2). This nadir of Cyr61 expression corresponds to the time of implantation and with the corresponding loss of endometrial estrogen receptors.23


Figure 225
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  		Fig. 2. Reverse transcriptase PCR for Cyr61 or ß-actin in RNA samples from normal endometrium throughout the menstrual cycle. Positive and negative controls are included. Note that expression of Cyr61 is highest in the proliferative and early secretory phase and significantly reduced during the mid-secretory phase, at the time of peak progesterone levels.

MacLaughlan. Cyr61 in Normal and Abnormal Endometrium. Obstet Gynecol 2007.

 

This pattern of expression using the semiquantitative methods of reverse transcriptase PCR was corroborated by immunohistochemical staining for the Cyr61 protein, performed in both normal and abnormal endometrium (Fig. 3). In the proliferative phase in both normal and PCOS women, Cyr61 staining is intense, as shown by the brown staining over the epithelial and stromal compartments (Figs. 3A, B). In the midsecretory phase, this staining largely disappears in the normal samples (Fig. 3C) but persists in midsecretory endometrium from PCOS women (Fig. 3D). These immunohistochemical data are summarized in Figure 4, which shows the mean HSCORE (±standard error) for normal and PCOS endometrium for each cell type (glands, stroma, and luminal epithelium). As indicated by asterisks, the midsecretory phase endometrium from PCOS had an abnormally high level of expression of Cyr61, compared with normal midsecretory endometrium (P<.01). The pattern of Cyr61 expression shown in Figures 3A–D was mirrored by the expression of estrogen receptor (ER)-{alpha} (ER-{alpha}; Fig. 3E–H), Ki67, a marker of proliferation (Figs. 3I–L), and another early immediate gene, cFos (Figs. 3M–P).


Figure 325
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  		Fig. 3. Immunohistochemical staining for Cyr61 in normal and abnormal endometrium. Cyr61 is up-regulated in the proliferative phase of both normal (A) and polycystic ovarian syndrome (PCOS) (B) endometrium. It is absent in normal mid-secretory phase endometrium (C) but elevated in the mid-secretory phase endometrium of women with PCOS (D). The immunostaining pattern for Cyr61 correlates well with that of estrogen receptor-{alpha} (E–H), the nuclear marker of proliferation, Ki67 (I–L), and another early immediate gene, cFos (M–P). Bars represent 50 µM. Immunostaining with specific antibodies was performed as described in Materials and Methods.

MacLaughlan. Cyr61 in Normal and Abnormal Endometrium. Obstet Gynecol 2007.

 

Figure 425
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  		Fig. 4. Immunhistochemical staining of Cyr61 comparing expression in different cell types (glands, black bars; lumen, white bars; stroma, striped bars) in normal endometrium and endometrium from women with polycystic ovarian syndrome (PCOS) in the proliferative and midsecretory phase of the menstrual cycle. The semiquantitative histologic score (HSCORE)22 was determined by blinded observations by two observers and calculated as described in Materials and Methods. Note that midsecretory phase endometrium from normal women expressed reduced Cyr61. Compared with normal midsecretory samples, PCOS women continued to express significantly more Cyr61 in the midsecretory phase (P<.01).

MacLaughlan. Cyr61 in Normal and Abnormal Endometrium. Obstet Gynecol 2007.

 

To compare the normal and PCOS endometrium with pathologic endometrium, we examined the expression of Cyr61 mRNA in endometrioid adenocarcinoma by reverse transcriptase PCR and compared it with mRNA from cycling endometrium from fertile controls. As shown in Figure 5 (upper panel), compared with proliferative and midsecretory samples, overall mRNA expression appeared higher for Cyr61 in endometrial adenocarcinoma samples. Statistically, mRNA expression in the midsecretory phase was significantly reduced compared with proliferative and adenocarcinoma samples normalized against ß-actin (see lower panel).


Figure 525
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  		Fig. 5. Reverse transcriptase polymerase chain reaction assay for Cyr61 in normal endometrium, from the proliferative and secretory phase and in samples of cancer. A summary bar graph of the relative absorbance for each group is shown in panel A. Reverse transcriptase polymerase chain reaction results of Cyr61 expression for three separate samples using ß-actin as a control band is shown in panel B with positive and negative controls.

MacLaughlan. Cyr61 in Normal and Abnormal Endometrium. Obstet Gynecol 2007.

 

An immunohistochemical survey and comparison of Cyr61 expression in endometrial hyperplasia without and with atypia and in endometrioid adenocarcinoma is shown in Figure 6A. Normal midsecretory phase endometrium had significantly reduced Cyr61 expression (P<.01), compared with proliferative endometrium or midsecretory PCOS; hyperplasia and cancer samples exhibited similar levels of Cyr61 to proliferative phase endometrium. Cyr61 immunostaining, as judged by HSCORE, was compared between different tumor grades in the adenocarcinoma samples. As shown in Figure 6B, overall Cyr61 staining was similar in all grades of endometrial adenocarcinoma, compared with proliferative endometrium. Midsecretory immunostaining in normal endometrium was low or absent.


Figure 625
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  		Fig. 6. Histologic score (HSCORE) summary for immunostaining results of Cyr61 protein showed that normal midsecretory endometrium expressed significantly lower levels of Cyr61 compared with normal proliferative or midsecretory polycystic ovarian syndrome (PCOS) endometrium, endometrial hyperplasia, and endometrioid adenocarcinoma (P<.01) (A). Midsecretory endometrium from normal women expressed significantly less Cyr61 (P<.01 in A and B). Cyr61 HSCORE results were compared for different tumor grades (B). No differences in Cyr61 expression were noted by grade of the tumor.

MacLaughlan. Cyr61 in Normal and Abnormal Endometrium. Obstet Gynecol 2007.

 

Examples of immunohistochemical staining are shown in Figure 7; hyperplasia without (A) and with atypia (B) both stained strongly for Cyr61. A few of endometrioid adenocarcinoma samples were negative for Cyr61 (C), but most expressed this protein (D). Interestingly, immunostaining for the estrogen receptor (ER-{alpha}) appeared to coincide with this pattern of Cyr61 expression (insets).


Figure 725
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  		Fig. 7. Immunohistochemical staining in endometrial hyperplasia and cancer. Examples of Cyr61 expression endometrial hyperplasia without (A) and with (B) atypia are shown, along with examples of rare negative staining in endometrial cancer (C) and more typical positive Cyr61 immunostaining (D). An apparent correlation between estrogen receptors and the expression of Cyr61 was noted (insets). Black bars represent 50 µM. Immunostaining was performed as described in Materials and Methods.

MacLaughlan. Cyr61 in Normal and Abnormal Endometrium. Obstet Gynecol 2007.

 


   DISCUSSION
TOP
ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
As a group, women with PCOS bear a disproportionate risk for the development of endometrial hyperplasia and cancer.1,24–26 The PCOS endometrium has been shown to exhibit differences from normal endometrium, including elevated levels of ER-{alpha}, androgen receptor, and steroid receptor coactivators.27,28Cyr61 is an early immediate gene that is associated with certain malignancies, including breast, ovarian, and gastric cancers.17,29–33 Dysfunctional expression patterns of Cyr61 has been reported in gynecologic conditions such as endometriosis and uterine leiomyomata.10,34 Previous work has demonstrated that Cyr61 expression is up-regulated by estrogen in hormone-responsive breast cancer cell line,33 consistent with our observation of significantly higher expression in the proliferative phase endometrium than in the midsecretory phase of normal cycling patients. In this study we confirmed this estrogen dependence of Cyr61 expression in an endometrial cell line and report the new observation of elevated expression of Cyr61 in secretory PCOS endometrium, maintaining levels of Cyr61 similar to hyperplasia and endometrioid adenocarcinoma.

In normal endometrium, Cyr61 appears during the proliferative phase, at the time of maximal epithelial cell division. Its expression corresponds to the peak in estrogen receptors (ER-{alpha}) that climb during the proliferative phase before declining in the secretory phase of the menstrual cycle, a time of peak progesterone action.35 As estrogen receptors disappear under the influence of ovulatory progesterone, so apparently does the expression of Cyr61, as shown in the present study.

Cyr61 is overexpressed in the endometrium of ovulatory PCOS patients, remaining abnormally high into the midsecretory phase. This extended expression of Cyr61 into the midsecretory phase noted in this study correlates with elevations in ER-{alpha} and other markers of cell proliferation, including Ki67 and cFos.28 Indeed, the high levels of expression of Cyr61 in most of the samples of endometrial carcinoma studied suggest a high level of estrogen sensitivity in these endometrioid tumors, which may be driving this Cyr61 expression. The increased estrogen sensitivity seen in PCOS endometrium may also denote a relative insensitivity to progesterone.

The association between Cyr61 and persistent estrogen receptor activity in PCOS endometrium is interesting. In at least one case where Cyr61 was lacking, ER-{alpha} was also not expressed. Could the Cyr61 be driven by locally produced estrogen? Breast cancer cells and endometrial carcinomas are capable of producing estrogen locally through elaboration of the P450 aromatase enzyme.36,37 Further study will be needed to demonstrate whether Cyr61 expression in some tumors becomes independent of estrogen receptor expression and activity or if PCOS endometrium expresses P450 aromatase activity.

The functional significance of Cyr61 overexpression remains controversial. Cyr61 may confer a more aggressive phenotype on cells that express this extracellular protein. Cyr61 is an angiogenic factor that has roles in cell adhesion and migration.4 It has been shown to promote tumorigenesis and invasion in breast cancer and gastric tumors9,10,38 thought to involve integrin-binding sequences.39 In prostate, Cyr61 expression was reported to be reduced in cancer compared with normal tissues.6 Only one previous study has been reported on Cyr61 in endometrial cancer. In that report, Chien et al18 reported an inverse relationship between Cyr61 expression and growth of endometrial cancer cells. Most of the data presented in that study were obtained after examination of cancer cell lines. In the portion of their study that did examine endometrial cancers, the authors compared Cyr61 mRNA expression in eight tumor samples with eight randomly selected normal tissue samples. The expression of Cyr61 in the control samples was highly variable, and it is unclear if these were age-matched controls or if the phase of the endometrium was known.

With a larger collection of samples than that used, we find that Cyr61 is expressed in endometrial hyperplasia with and without atypia and in most adenocarcinoma samples. These results are consonant with the previous reports of Cyr61 expression in breast cancer. Interestingly, Cyr61 expression appears to be regulated through a G-protein–coupled estrogen receptor, GPR30 (Young et al, 2007 [abstract]). GPR30 was recently shown to be a marker of poor prognosis in endometrial cancer.40 Results based on our study raise the possibility that poor prognosis in endometrial cancer (and perhaps the risk of hyperplasia in PCOS) may be mediated, in part, through Cyr61. Based on these findings, we postulate that PCOS endometrium may be exhibiting a pattern of estrogen sensitivity or progesterone insensitivity that predisposes these patients to the development of endometrial hyperplasia and cancer. Cyr61 may thus be an early marker of this change toward cell proliferation and could be useful in other clinical situations, including the monitoring of women on hormone replacement and women with endometriosis or endometrial polyps. Further, Cyr61 may find utility as a marker of uterine receptivity in women with infertility or pregnancy loss.

The importance in these findings lies in the observation of elevated expression of Cyr61 in PCOS endometrium. Failure to down-regulate this estrogen-regulated marker of cellular proliferation and invasive behavior is further evidence of a proliferative phenotype of the endometrium in PCOS. Given the regulation of Cyr61 by GPR30, it will be important to assess prospectively whether Cyr61 is an independent prognostic factor for survival prognosis in patients with endometrial cancers. Accumulating evidence also suggests that Cyr61 may be useful for the assessment of uterine receptivity in infertile women.


   Footnotes
 
Supported in part by the National Institute of Health and Human Development/National Institutes of Health through cooperative agreement U54 HD-35041 (B.A.L.) as part of the Specialized Cooperative Centers Program in Reproduction Research and Fogarty International Fellowship Award (to W.A.P.).

The authors thank the Gynecologic Oncology Group for providing endometrial adenocarcinoma samples used in this study.

Presented as the prize paper for the Donald F. Richardson Award, Annual Clinical Meeting of the American College of Obstetricians and Gynecologists, Washington, DC, May 6–10, 2006.

Corresponding author: Bruce A. Lessey MD, PhD, 890 W. Faris Road, Suite 470, Greenville, SC 29605; e-mail: blessey{at}ghs.org.

Financial Disclosure The authors have no potential conflicts of interest to disclose.

doi:10.1097/01.AOG.0000269047.46078.28


   REFERENCES
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ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
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I. Gashaw, S. Stiller, C. Boing, R. Kimmig, and E. Winterhager
Premenstrual Regulation of the Pro-Angiogenic Factor CYR61 in Human Endometrium
Endocrinology, May 1, 2008; 149(5): 2261 - 2269.
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