EZH2 Mediates Proliferation, Migration, and Invasion Promoted by Estradiol in Human Glioblastoma Cells.

Glioblastomas (GBM) are the most frequent and aggressive brain tumors. 17ß-estradiol (E2) increases proliferation, migration, and invasion of human GBM cells; however underlying mechanisms are no fully understood. Zeste 2 Enhancer Homologous enzyme (EZH2) is a methyltransferase part of Polycomb 2 repressor complex (PRC2). In GBM, EZH2 is overexpressed and involved in the cell cycle, migration, and invasion processes. We studied the role of EZH2 in the pro-oncogenic actions of E2 in human GBM cells. EZH2 gene silencing and pharmacological inhibition of EZH2 blocked proliferation, migration, and invasion of GBM cells induced by E2. We identified in silico additional putative estrogen response elements (EREs) at the EZH2 promoter, but E2 did not modify EZH2 expression. In silico analysis also revealed that among human GBM samples, EZH2 expression was homogeneous; in contrast, the heterogeneous expression of estrogen receptors (ERs) allowed the classification of the samples into groups. Even in the GBM cluster with high expression of ERs and those of their target genes, the expression of PCR2 target genes did not change. Overall, our data suggest that in GBM cells, pro-oncogenic actions of E2 are mediated by EZH2, without changes in EZH2 expression and by mechanisms that appear to be unrelated to the transcriptional activity of ERs.

Is There a Role for Sex Hormone Receptors in Head-and-neck Cancer? Links with HPV Infection and Prognosis.

BACKGROUND/AIM: Head-and-neck squamous cell carcinoma (HNSCC) is the fifth most common cancer in the world and human papillomavirus (HPV) is an important risk factor for this neoplasm. Recent studies showed an association between sex hormone receptors and pathogenesis and/or prognosis in patients with HNSCC. The aim of this study was to clarify the expression patterns of sex hormone receptors in HPV-positive and HPV-negative HNSCC and their associations with tumour biopathology and biological behaviour. MATERIALS AND METHODS: Scientific literature indexed in PubMed about sex hormone receptors in HNSCC was retrieved and critically analyzed, to obtain an overview of expression patterns and their possible implications for tumour biopathology and prognosis. RESULTS: Sex hormone receptors were more frequently detected in oropharyngeal tumours compared with HNSCC from other locations. ERα was associated with HPV-positive tumours. The androgen and progesterone receptors were associated with poor patient prognosis. Estrogen receptor alpha (ERα) is implicated in the biopathology of HNSCC in different ways, by promoting DNA hypermutation and facilitating HPV integration thus contributing to an immunogenic phenotype, but also by cooperating with the epithelial growth factor receptor (EGFR) to promote resistance to therapy. CONCLUSION: The expression of sex hormone receptors may be of prognostic value in specific tumour subgroups, but the use of hormonal therapies for HNSCC is still not in close sight.

The rs1256031 of estrogen receptor ß gene is associated with type 2 diabetes.

AIM: To determine the association between the rs1256031 polymorphism and risk of developing type 2 diabetes. MATERIALS AND METHODS: Cases and controls study. 597 individuals with type 2 diabetes and 605 without it participated. Genotyping of the rs1256031 polymorphism of the ERß gene was performed by real-time PCR using TaqMan assay. For the multivariate analysis, a multiple logistic regression was performed that included the main confounding variables. RESULTS AND CONCLUSION: A multiple logistic regression analysis was performed, adjusting for age, WHR, BMI and gender. The dominant model showed a protective effect compared to the TT genotype (OR = 0.596, IC95% [0.458-0.776]). DISCUSSION: The proportions of native American, European and African ancestry were characterized and no difference was found in the study groups. The protective effect obtained in the dominant model could to be due a regulatory function in the transcription or the processing of the primary transcript. Our result are the first to report an association between the polymorphism rs1256031 and the reduction of the risk of T2D in the Mexican population. The rs1256031 polymorphism show reduced risk of developing T2D and is potential markers for predicting T2D.

Effects of Estrogen Therapy on the Serotonergic System in an Animal Model of Perimenopause Induced by 4-Vinylcyclohexen Diepoxide (VCD).

Chronic exposure to 4-vinylcycloxene diepoxide (VCD) in rodents accelerates the natural process of ovarian follicular atresia modelling perimenopause in women. We investigated why estrogen therapy is beneficial for symptomatic women despite normal or high estrogen levels during perimenopause. Female rats (28 d) were injected daily with VCD or oil for 15 d; 55-65 d after the first injection, pellets of 17ß-estradiol or oil were inserted subcutaneously. Around 20 d after, the rats were euthanized (control rats on diestrus and estradiol-treated 21 d after pellets implants). Blood was collected for hormone measurement, the brains were removed and dorsal raphe nucleus (DRN), hippocampus (HPC), and amygdala (AMY) punched out for serotonin (5-HT), estrogen receptor ß (ERß), and progesterone receptor (PR) mRNA level measurements. Another set of rats was perfused for tryptophan hydroxylase (TPH) immunohistochemistry in the DRN. Periestropausal rats exhibited estradiol levels similar to controls and a lower progesterone level, which was restored by estradiol. The DRN of periestropausal rats exhibited lower expression of PR and ERß mRNA and a lower number of TPH cells. Estradiol restored the ERß mRNA levels and number of serotonergic cells in the DRN caudal subregion. The 5-HT levels were lower in the AMY and HPC in peristropausal rats, and estradiol treatment increased the 5-HT levels in the HPC and also increased ERß expression in this area. In conclusion, estradiol may improve perimenopause symptoms by increasing progesterone and boosting serotonin pathway from the caudal DRN to the dorsal HPC potentially through an increment in ERß expression in the DRN.

Estrogen receptor ß regulates the tumoral suppressor PTEN to modulate pituitary cell growth.

In this study, we focused on ERß regulation in the adenohypophysis under different estrogenic milieu, by analyzing whether ER modulates the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expression and its subcellular localization on anterior pituitary glands from Wistar rats and GH3 lactosomatotroph cells that over-expressed ERß. ERß was regulated in a cyclic manner, and underwent dynamic changes throughout the estrous cycle, with decreased ERß+ cells in estrus and under E2 treatment, but increased in ovariectomized rats. In addition, the ERα/ß ratio increased in estrus and under E2 stimulation, but decreased in ovariectomized rats. Double immunofluorescence revealed that lactotroph and somatotroph ERß+ were significantly decreased in estrus. Also, variations in the PTEN expression was observed, which was diminished with high E2 conditions but augmented with low E2 milieu. The subcellular localization of this phosphatase was cell cycle-dependent, with remarkable changes in the immunostaining pattern: nuclear in arrested pituitary cells but cytoplasmic in stimulated cells, and responding differently to ER agonists, with only DPN being able to increase PTEN expression and retaining it in the nucleus. Finally, ERß over-expression increased PTEN with a noticeable subcellular redistribution, and with a significant nuclear signal increase in correlation with an increase of cells in G0/G1 phase. These results showed that E2 is able to inhibit ERß expression and suggests that the tumoral suppressor PTEN might be one of the signaling proteins by which E2, through ERß, acts to modulate pituitary cell proliferation, thereby adapting endocrine populations in relation with hormonal necessities.

Inhibitory role of ERß on anterior pituitary cell proliferation by controlling the expression of proteins related to cell cycle progression.

Considering that the role of ERß in the growth of pituitary cells is not well known, the aim of this work was to determine the expression of ERß in normal and tumoral cells and to investigate its implications in the proliferative control of this endocrine gland, by analyzing the participation of cyclin D1, Cdk4 and p21. Our results showed that the expression of ERß decreased during pituitary tumoral development induced by chronic E2 stimulation. The 20 ± 1.6% of normal adenohypophyseal cells expressed ERß, with this protein being reduced in the hyperplastic/adenomatous pituitary: at 20 days the ERß+ population was 10.7 ± 2.2%, while after 40 and 60 days of treatment an almost complete loss in the ERß expression was observed (40 d: 1 ± 0.6%; 60 d: 2 ± 0.6%). The ERα/ß ratio increased starting from tumors at 40 days, mainly due to the loss of ERß expression. The cell proliferation was analyzed in normal and hyperplastic pituitary and also in GH3ß- and GH3ß+ which contained different levels of ERß expression, and therefore different ERα/ß ratios. The over-expression of ERß inhibited the GH3 cell proliferation and expression of cyclin D1 and ERα. Also, the ERß activation by its agonist DPN changed the subcellular localization of p21, inducing an increase in the p21 nuclear expression, where it acts as a tumoral suppressor. These results show that ERß exerts an inhibitory role on pituitary cell proliferation, and that this effect may be partially due to the modulation of some key regulators of the cell cycle, such as cyclin D1 and p21. These data contribute significantly to the understanding of the ER effects in the proliferative control of pituitary gland, specifically related to the ERß function in the E2 actions on this endocrine gland.