Wild-Type Estrogen Receptor Beta Expression in Normal and Neoplastic Paraffin-Embedded Tissues

Fulvestrant inhibits growth of triple negative breast cancer and synergizes with tamoxifen in ERα positive breast cancer by up-regulation of ERβ

The estrogen receptor-alpha (ERα) is used as a predictive marker for anti-estrogen therapy in breast cancer patients. In addition to aromatase inhibitors, ERα can be targeted at the receptor level using the receptor modulator tamoxifen or by the pure anti-estrogen fulvestrant. The role of the second ER, ER-beta (ERβ), as a therapeutic target or prognostic marker in breast cancer is still elusive. Hitherto, it is not known if ERα+/ERβ+ breast cancers would benefit from a treatment strategy combining tamoxifen and fulvestrant or if fulvestrant exert any therapeutic effects in ERα-/ERβ+ breast cancer. Here, we report that fulvestrant up-regulated ERβ in ERα+/ERβ+ breast cancer and in triple negative ERβ+ breast cancers (ERα-/ERβ+). In ERα+/ERβ+ breast cancer, a combination therapy of tamoxifen and fulvestrant significantly reduced tumor growth compared to either treatment alone both in vivo and in vitro. In ERα-/ERβ+ breast cancer fulvestrant had potent effects on cancer growth, in vivo as well as in vitro, and this effect was dependent on intrinsically expressed levels of ERβ. The role of ERβ was further confirmed in cells where ERβ was knocked-in or knocked-down. Inhibition of DNA methyltransferase (DNMT) increased the levels of ERβ and fulvestrant exerted similar potency on DNMT activity as the DNMT inhibitor decitabine. We conclude that fulvestrant may have therapeutic potential in additional groups of breast cancer patients; i) in ERα+/ERβ+ breast cancer where fulvestrant synergizes with tamoxifen and ii) in triple negative/ERβ+ breast cancer patients, a subgroup of breast cancer patients with poor prognosis.

Perinatal exposure to diethylstilbestrol alters the functional differentiation of the adult rat uterus

The exposure to endocrine disrupters and female reproductive tract disorders has not been totally clarified. The present study assessed the long-term effect of perinatal (gestation+lactation) exposure to diethylstilbestrol (DES) on the rat uterus and the effect of estrogen replacement therapy. DES (5μg/kg bw/day) was administered in the drinking water from gestational day 9 until weaning and we studied the uterus of young adult (PND90) and adult (PND360) females. To investigate whether perinatal exposure to DES modified the uterine response to a long-lasting estrogen treatment, 12-month-old rats exposed to DES were ovariectomized and treated with 17β-estradiol for 3 months (PND460). In young adult rats (PND90), the DES treatment decreased both the proliferation of glandular epithelial cells and the percentage of glandular perimeter occupied by α-smooth muscle actin-positive cells. The other tissue compartments remained unchanged. Cell apoptosis was not altered in DES-exposed females. In control adult rats (PND360), there were some morphologically abnormal uterine glands. In adult rats exposed to DES, the incidence of glands with cellular anomalies increased. In response to estrogens (PND460), the incidence of cystic glands increased in the DES group. We observed glands with daughter glands and conglomerates of glands only on PND460 and in response to estrogen replacement therapy, independently of DES exposure. The p63 isoforms were expressed without changes on PND460. Estrogen receptors α and β showed no changes, while the progesterone receptor decreased in the subepithelial stroma of DES-exposed animals with estrogen treatment. The long-lasting effects of perinatal exposure to DES included the induction of abnormalities in uterine tissues of aged female rats and an altered response of the adult uterus to estradiol.

Expression of wild-type estrogen receptor beta protein in human breast cancer: specific correlation with HER2/neu overexpression

Expression of estrogen receptor beta (ERbeta) protein in human breast cancer and correlation with clinicopathological factors have been reported by many investigators, but many of them used ERbeta antibodies that react with both wild-type ERbeta (ERbetawt) and splicing variant isoform. Therefore, the frequency and correlation with clinicopathological factors of ERbetawt expression remain to be established. In the present study a monoclonal antibody EMR02, specific for ERbetawt, was used in formalin-fixed paraffin-embedded sections from 225 female primary breast cancer patients diagnosed as having invasive ductal carcinoma. Expression of ERalpha, progesterone receptor (PgR) and HER2/neu were also investigated by immunohistochemistry. For ERbetawt, ERalpha and PgR, positivity was defined as nuclear staining in >10% of the cancer cells. HER2/neu overexpression was defined as a Hercep test score 3+. Positivity for ERbetawt, ERalpha, PgR and HER2/neu overexpression was 55%, 74%, 61% and 25%, respectively. The expression of ERbetawt had a positive correlation with ERalpha (P=0.018) and PgR (P=0.02). There was significant positive correlation between ERbetawt expression and HER2/neu overexpression (P<0.0001). According to multivariate logistic regression analysis the most significant association was between ERbetawt expression and HER2/neu overexpression (P<0.0001). These results suggest that clinical significances of ERbetawt expression in human breast cancer patients may be more complex.

Immunoreactivity for Sex Steroid Hormone Receptors in Pulmonary Hamartomas

Sex steroid hormone [ie, estrogen (ER), progesterone (PgR), and androgen (AR)] receptors have been identified previously in normal salivary glands and, more variably, in salivary gland and salivary gland-type tumors. No data are available, however, on their expression in pulmonary hamartoma, a benign biphasic tumor consisting of reactive epithelial cells and neoplastic fibromyxoid stroma, cartilage and fat, which shares some morphologic, immunophenotypic, and genotypic features to pleomorphic adenoma of major salivary glands. Thirty pulmonary hamartomas (15 in male patients and 15 in age-matched female patients), were evaluated for ER, PgR, and AR immunoreactivity, and also for mesenchymal, epithelial, and myoepithelial markers, in the fibromyxoid, epithelial, and chondroid components. ER immunoreactivity was encountered in 90% of hamartomas, PgRs in 90%, and ARs in 53% (P<0.001), but not in normal lung tissues. ARs were confined to males (P<0.001), with a marginal prevalence in the fibromyxoid component (P=0.067). PgRs and ERs were instead present in both sex, with the former being restricted to the fibromyxoid stromal component (P<0.001) and the latter preferentially located in epithelial cells (P=0.107). In most cases, fibromyxoid stroma and spindle cells surrounding the chondroid foci displayed simultaneous immunoreactivity for ERs, PgRs, and ARs, along with immunoreactivity for vimentin, S-100 protein, glial fibrillary acid protein, smooth muscle actin, and calponin but lack of staining for cytokeratins. This profile is consistent with an incomplete myoepithelial differentiation of the receptor-expressing mesenchymal cells. In conclusion, sex steroid hormone receptor expression is a nonrandom event in pulmonary hamartoma, and may be related to the development and growth of this tumor.

Differential expression of oestrogen receptors in human secondary lymphoid tissues

Many autoimmune diseases including rheumatoid arthritis (RA), Sjögren's syndrome (SS) and systemic lupus erythematosus (SLE) occur much more frequently in women than in men. There is much evidence that oestrogen is the major cause of this gender difference. Interestingly, oestrogen relieves the symptoms of RA and SS but it exacerbates SLE. This contradictory effect of oestrogen on autoimmune diseases is not well understood. Most of the effects of oestrogen are mediated by two receptors: oestrogen receptor alpha and beta (ERalpha and ERbeta). To determine whether these contradictory effects of oestrogen relate to the involvement of distinct effects of the two ERs, we investigated expression of ERalpha and ERbeta in human secondary lymphoid tissues. We observed that, in tonsils, ERbeta is expressed in lymphocytes of germinal centres (GC) and the follicular mantle zone as well as in granulocytes, while ERalpha is expressed only in activated germinal centres but not in the follicular zone. ERbeta is the predominant ER in human leucocytes from peripheral blood, spleen and in leucocytes infiltrating cancers in both males and females. In addition, in different human lymphoma cell lines including Hodgkin lymphoma, Burkitt lymphoma, and multiple myeloma, ERbeta is abundant while ERalpha is not detectable. Our results indicate that ERbeta is the predominant type of ER in mature lymphocytes. We suggest that ERalpha and ERbeta have distinct roles in secondary lymphoid tissues and that further studies with ERbeta-specific agonists will help to elucidate the role of ERbeta in these tissues.