Cytoplasmic expression of estrogen receptor beta (ERβ) predicts poor clinical outcome in advanced serous ovarian cancer

Targeting estrogen receptor subtypes (ERα and ERβ) with selective ER modulators in ovarian cancer

Ovarian cancer cells express both estrogen receptor α (ERα) and ERβ, and hormonal therapy is an attractive treatment option because of its relatively few side effects. However, estrogen was previously shown to have opposite effects in tumors expressing ERα compared with ERβ, indicating that the two receptor subtypes may have opposing effects. This may explain the modest response to nonselective estrogen inhibition in clinical practice. In this study, we aimed to investigate the effect of selectively targeting each ER subtype on ovarian cancer growth. Ovarian cancer cell lines SKOV3 and OV2008, expressing both ER subtypes, were treated with highly selective ER modulators. Sodium 3'-(1-(phenylaminocarbonyl)-3,4-tetrazolium)-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate (XTT) assay revealed that treatment with 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP) (ERα antagonist) or 2,3-bis(4-hydroxy-phenyl)-propionitrile (DPN) (ERβ agonist) significantly suppressed cell growth in both cell lines. In contrast, 4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol (PPT) (ERα agonist) or 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]-pyrimidin-3-yl]phenol (PHTPP) (ERβ antagonist) significantly enhanced cell growth. These results were confirmed on a xenograft model where SKOV3 cells were injected s.c. into ovariectomized mice. We observed that the average size of xenografts in both the DPN-treated group and the MPP-treated group was significantly smaller than that for the vehicle-treated group. In addition, we found that phospho-AKT expressions in SKOV3 cells were reduced by 80% after treatment with MPP and DPN, indicating that the AKT pathway was involved. The combined treatment with MPP and DPN had a synergistic effect in suppressing ovarian cancer cell growth. Our findings indicate that targeting ER subtypes may enhance the response to hormonal treatment in women with ovarian cancer.

Analysis of the contribution of immunologically-detectable HER2, steroid receptors and of the "triple-negative" tumor status to disease-free and overall survival of women with epithelial ovarian cancer

We assessed associations between steroid receptors including: estrogen-alpha, estrogen-beta, androgen receptor, progesterone receptor, the HER2 status and triple-negative epithelial ovarian cancer (ERα-/PR-/HER2-; TNEOC) status and survival in women with epithelial ovarian cancer. The study included 152 women with primary epithelial ovarian cancer. The status of steroid receptor and HER2 was determined by immunohistochemistry. Disease-free and overall survival were calculated and compared with steroid receptor and HER2 status as well as clinicopathological features using the Cox Proportional Hazards model. A mean follow-up period of 43.6 months (interquartile range=41.4 months) was achieved where 44% of patients had serous tumor, followed by mucinous (23%), endometrioid (9%), mixed (9%), undifferentiated (8.5%) and clear cell tumors (5.3%). ER-alpha staining was associated with grade II-III tumors. Progesterone receptor staining was positively associated with a Body Mass Index≥25. Androgen receptor positivity was higher in serous tumors. In stand-alone analysis of receptor contribution to survival, estrogen-alpha positivity was associated with greater disease-free survival. However, there was no significant association between steroid receptor expression, HER2 status, or TNEOC status, and overall survival. Although estrogen-alpha, androgen receptor, progesterone receptor and the HER2 status were associated with key clinical features of the women and pathological characteristics of the tumors, these associations were not implicated in survival. Interestingly, women with TNEOC seem to fare the same way as their counterparts with non-TNEOC.

Autocrine production of interleukin-6 confers ovarian cancer cells resistance to tamoxifen via ER isoforms and SRC-1

Although 40-60% of ovarian cancer (OVCA)s express estrogen receptor (ER)α, only a minor proportion of patients respond to anti-estrogen treatment with ER antagonist tamoxifen (TAM). The mechanism underlying TAM resistance in the course of OVCA progression is incompletely understood. However, interleukin-6 (IL-6) plays a critical role in the development and progression of OVCA. Here we explore an association between IL-6 and TAM resistance. We demonstrate that both exogenous (a relatively short period of treatment with recombinant IL-6) and endogenous IL-6 (by transfecting with plasmid encoding for sense IL-6) induce TAM resistance in non-IL-6-expressing A2780 cells, while deleting of endogenous IL-6 expression in IL-6-overexpressing CAOV-3 cells (by transfecting with plasmid encoding for antisense IL-6) promotes the sensitivity of these cells to TAM. Further investigation indicates that TAM resistance caused by IL-6 is associated with the alteration of ERα, ERβ and steroid hormone receptor coactivator (SRC)-1 expression levels, the protein interactions between SRC-1 and ERα, but not ERβ, as well as blockage of estrogen-induced ER receptor nuclear translocation. These results show that IL-6 secreted by OVCA cells may contribute to the refractoriness of these cells to TAM via ER isoforms and SRC-1. Overexpression of IL-6 not only plays an important role in OVCA progression but also contributes to TAM resistance. Our studies suggest that TAM-IL-6-targeted adjunctive therapy may lead to a more effective intervention than TAM alone.

Prognostic significance of the estrogen receptor beta (ERβ) isoforms ERβ1, ERβ2, and ERβ5 in advanced serous ovarian cancer

OBJECTIVE

In the present study we have examined the pattern of expression of the full length estrogen receptor β (ERβ1) and two ERβ splice variant isoforms (ERβ2, ERβ5) in well-characterized advanced serous ovarian cancers.

METHODS

Immunohistochemistry was performed with ERβ1, ERβ2, and ERβ5 antibodies and results were correlated with pathological and clinical follow-up data. Expression of ERβ isoforms in a panel of ovarian cancer cell lines and human tumor xenografts was also assessed.

RESULTS

Immunohistochemical staining revealed cellular compartment-specific distribution for each isoform in malignant ovarian tissues exhibiting both nuclear staining and cytoplasmic staining. Patients with cytoplasmic ERβ2 expression had significantly worse outcome (p = 0.006 at the multivariate analysis), the 5-year survival rate being nearly 28% for patients who did express cytoplasmic ERβ2, and 60% in negative patients. Cytoplasmic ERβ2 expression was also found to be significantly associated with chemoresistance. In concordance with clinical results both nuclear and cytoplasmic expressions were observed for the three isoforms in the cancer cell lines and human tumor xenografts tested.

CONCLUSIONS

This is the first study to uncover an unfavorable prognostic role of ERβ2 in advanced serous ovarian cancer. If anomalies of ERβ2 cytoplasmic expression could be demonstrated to represent an independent unfavorable prognostic marker and/or a marker predicting chemoresistance in advanced serous ovarian cancer, its immunohistochemical assessment at the time of surgery, could help to recognize candidates for clinical trials of new interventions.

Prognostic role of hormone receptors in ovarian cancer: a systematic review and meta-analysis

OBJECTIVE

The aim of this study was to summarize the global predicting role of hormone receptors for survival in ovarian cancer.

METHODS

Eligible studies were identified and assessed for quality through multiple search strategies. Data were collected from studies comparing overall or progression-free/disease-free/relapse-free survival in patients with elevated levels of estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER2) with those in patients with lower levels. Studies were pooled, and combined hazards ratios (HRs) of ER, PR, and HER2 for survival were calculated, respectively.

RESULTS

A total of 35 studies were included for meta-analysis (23 for ER, 19 for PR, and 8 for HER2). For overall survival, the pooled HR of PR reached 0.88 [95% confidence interval (CI), 0.82-0.95], which means that elevated PR level could significantly indicate better survival. In contrast, elevated levels of HER2 could predict worse outcome with an HR of 1.41 (95% CI, 1.05-1.89). Increased level of ER was not significantly prognostic (HR, 0.94; 95% CI, 0.87-1.01). For progression-free survival/disease-free survival/recurrence-free survival, elevated PR level also had predictive value for better outcome with a pooled HR of PR of 0.80 (95% CI, 0.67-0.95). Oppositely, elevated HER2 level could predict poorer outcome with an HR of 1.55 (95% CI, 1.11-2.16). Estrogen receptor failed to predict outcome with an HR of 0.90 (95% CI, 0.78-1.03).

CONCLUSIONS

In patients with ovarian cancer, elevated level of PR predicted favorable survival, and elevated level of HER2 was associated with worse survival.

New insights on the role of hormonal therapy in ovarian cancer

Ovarian cancer (OVCA) is the most lethal gynecological malignancy. It is often diagnosed in advanced stages and despite therapy, 70% relapse within 2years with incurable disease. Regimens with clinical benefit and minimal toxicity are urgently needed. More effective hormonal therapies would be appealing in this setting. Estrogens (E2) are implicated in the etiology of OVCA. Estrogens drive proliferation and anti-estrogens inhibit ovarian cancer growth in vitro and in vivo. Despite estrogen receptor (ER) expression in 67% of OVCAs, small anti-estrogen therapy trials have been disappointing and the benefit of hormonal therapy has not been systematically studied in large well-designed trials. OVCAs often manifest de novo anti-estrogen resistance and those that initially respond invariably develop resistance. Estrogens stimulate ovarian cancer progression by transcriptional activation and cross talk between liganded ER and mitogenic pathways, both of which drive cell cycle progression. Estrogen deprivation and estrogen receptor (ER) blockade cause cell cycle arrest in susceptible OVCAs by increasing the cell cycle inhibitor, p27. This review summarizes and discusses scientific and epidemiological evidence supporting estrogen's role in ovarian carcinogenesis, provides an overview of clinical trials of ER blockade and aromatase inhibitors in OVCA and reviews potential causes of antiestrogen resistance. Anti-estrogen resistance was recently shown to be reversed by dual ER and Src signaling blockade. Blocking cross-talk between ER and constitutively activated kinase pathways may improve anti-estrogen therapeutic efficacy in OVCA, as has been demonstrated in other cancers. Novel strategies to improve benefit from anti-estrogens by combining them with targeted therapies are reviewed.

Expression of the glioma-associated oncogene homolog 1 (gli1) in advanced serous ovarian cancer is associated with unfavorable overall survival

Recent evidence links aberrant activation of Hedgehog (Hh) signaling with the pathogenesis of several cancers including medulloblastoma, glioblastoma, melanoma as well as pancreas, colorectal, and prostate carcinomas. Here we investigated the role of the transcription factor Gli1 in ovarian cancer. To this end, the expression profile of Gli1 was examined in normal ovaries, ovarian tumors, and ovarian cancer cell lines, and the in vitro effects of a specific Hh-pathway blocker, KAAD-cyclopamine, or a specific Gli1 inhibitor (GANT58) on cell proliferation and on Hh target gene expression were also assessed. Results obtained showed that epithelial cells in ovarian cancer tissue express significantly higher levels of nuclear Gli1 than in normal ovarian tissue, where the protein was almost undetectable. In addition, multivariate analysis showed that nuclear Gli1 was independently associated to poor survival in advanced serous ovarian cancer patients (HR = 2.2, 95%CI 1.0–5.1, p = 0.04). In vitro experiments demonstrated Gli1 expression in the three ovarian carcinoma cell lines tested, A2780, SKOV-3 and OVCAR-3. Remarkably, although KAAD-cyclopamine led to decreased cell proliferation, this treatment did not inhibit hedgehog target gene expression in any of the three ovarian cancer cell lines, suggesting that the inhibition of cell proliferation was a nonspecific or toxic effect. In line with these data, no differences on cell proliferation were observed when cell lines were treated with GANT58. Overall, our clinical data support the role of Gli1 as a prognostic marker in advanced serous ovarian cancer and as a possible therapeutic target in this disease. However, our in vitro findings draw attention to the need for selection of appropriate experimental models that accurately represent human tumor for testing future therapies involving Hh pathway inhibitors.

The expression ratios of estrogen receptor α (ERα) to estrogen receptor β1 (ERβ1) and ERα to ERβ2 identify poor clinical outcome in endometrioid endometrial cancer

The prognostic relevance of estrogen (ER) and progesterone receptor (PR) expression in endometrioid endometrial cancer is still controversially discussed. The present study has focused on the evaluation of the prognostic value of ERα, ERβ1, ERβ2, and PR in this histotype. Specifically, we were interested in evaluating whether the relative level of ER subtype-specific expression (in terms of a ratio ERα/ERβ1 and ERα/ERβ2) would predict clinical outcome better than their absolute levels in patients with endometrioid endometrial cancer. To this end, protein content was assessed by immunohistochemistry in a group of 121 cases and staining was analyzed in relation to clinicopathologic variables, disease-free survival and overall survival. Results obtained have demonstrated that none of the biological markers analyzed possess an independent prognostic role with regard to disease-free survival. Multivariate analysis of overall survival has shown that ERα alone is not an independent prognostic indicator in patients with endometrioid endometrial cancer (hazard ratio [HR]; 0.5; 95% confidence interval [CI], 0.09-3.0; P = .5). On the other hand, an ERα/ERβ1 ratio of 1 or less or an ERα/ERβ2 ratio of 1 or less has proved to be independently associated with a higher risk of death (HR, 6.4 [95% CI, 1.0-40.6; P = .04] and 9.7 [95% CI, 1.1-85.3; P = .04], respectively) along with age, tumor stage, and Ki-67. In conclusion, we report here that the ERα/ERβ1 and ERα/ERβ2 expression ratios are independent prognostic markers of survival in endometrioid endometrial cancer; these findings suggest that phenotyping these interacting markers conjointly may better predict patient survival than each individual marker alone.

Hormone response in ovarian cancer: time to reconsider as a clinical target?

Ovarian cancer is the sixth most common cancer worldwide among women in developed countries and the most lethal of all gynecologic malignancies. There is a critical need for the introduction of targeted therapies to improve outcome. Epidemiological evidence suggests a critical role for steroid hormones in ovarian tumorigenesis. There is also increasing evidence from in vitro studies that estrogen, progestin, and androgen regulate proliferation and invasion of epithelial ovarian cancer cells. Limited clinical trials have shown modest response rates; however, they have consistently identified a small subset of patients that respond very well to endocrine therapy with few side effects. We propose that it is timely to perform additional well-designed trials that should include biomarkers of response.

Hormone response in ovarian cancer: time to reconsider as a clinical target?

Ovarian cancer is the sixth most common cancer worldwide among women in developed countries and the most lethal of all gynecologic malignancies. There is a critical need for the introduction of targeted therapies to improve outcome. Epidemiological evidence suggests a critical role for steroid hormones in ovarian tumorigenesis. There is also increasing evidence from in vitro studies that estrogen, progestin, and androgen regulate proliferation and invasion of epithelial ovarian cancer cells. Limited clinical trials have shown modest response rates; however, they have consistently identified a small subset of patients that respond very well to endocrine therapy with few side effects. We propose that it is timely to perform additional well-designed trials that should include biomarkers of response.

Potential role of estrogen receptor beta as a tumor suppressor of epithelial ovarian cancer

Ovarian cancer is the gynecological cancer exhibiting the highest morbidity and improvement of treatments is still required. Previous studies have shown that Estrogen-receptor beta (ERβ) levels decreased along with ovarian carcinogenesis. Here, we present evidence that reintroduction of ERβ in BG-1 epithelial ovarian cancer cells, which express ERα, leads in vitro to a decrease of basal and estradiol-promoted cell proliferation. ERβ reduced the frequency of cells in S phase and increased the one of cells in G2/M phase. At the molecular level, we found that ERβ downregulated total retinoblastoma (Rb), phosphorylated Rb and phospho-AKT cellular content as well as cyclins D1 and A2. In addition, ERβ had a direct effect on ERα, by strongly inhibiting its expression and activity, which could explain part of the anti-proliferative action of ERβ. By developing a novel preclinical model of ovarian cancer based on a luminescent orthotopic xenograft in athymic Nude mice, we further revealed that ERβ expression reduces tumor growth and the presence of tumor cells in sites of metastasis, hence resulting in improved survival of mice. Altogether, these findings unveil a potential tumor-suppressor role of ERβ in ovarian carcinogenesis, which could be of potential clinical relevance for the selection of the most appropriate treatment for patients.

Estrogen receptors and human disease: an update

A myriad of physiological processes in mammals are influenced by estrogens and the estrogen receptors (ERs), ERα and ERβ. As we reviewed previously, given the widespread role for estrogen in normal human physiology, it is not surprising that estrogen is implicated in the development or progression of a number of diseases. In this review, we are giving a 5-year update of the literature regarding the influence of estrogens on a number of human cancers (breast, ovarian, colorectal, prostate, and endometrial), endometriosis, fibroids, and cardiovascular disease. A large number of sophisticated experimental studies have provided insights into human disease, but for this review, the literature citations were limited to articles published after our previous review (Deroo and Korach in J Clin Invest 116(3):561-570, 2006) and will focus in most cases on human data and clinical trials. We will describe the influence in which estrogen's action, through one of or both of the ERs, mediates the aforementioned human disease states.