The proliferative effect of estradiol on human prostate stromal cells is mediated through activation of ERK

YAP-mediated GPER signaling impedes proliferation and survival of prostate epithelium in benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) occurs when there is an imbalance between the proliferation and death of prostate cells, which is regulated tightly by estrogen signaling. However, the role of G protein-coupled estrogen receptor (GPER) in prostate cell survival remains ambiguous. In this study, we observed that prostates with epithelial hyperplasia showed increased yes-associated protein 1 (YAP) expression and decreased levels of estrogen and GPER. Blocking YAP through genetic or drug interventions led to reduced proliferation and increased apoptosis in the prostate epithelial cells. Interestingly, GPER agonists produced similar effects. GPER activation enhanced the phosphorylation and degradation of YAP, which was crucial for suppressing cell proliferation and survival. The Gαs/cAMP/PKA/LATS pathway, downstream of GPER, transmitted signals that facilitated YAP inhibition. This study investigated the interaction between GPER and YAP in the prostate epithelial cells and its contribution to BPH development. It lays the groundwork for future research on developing BPH treatments.

The ERα-NRF2 signalling axis promotes bicalutamide resistance in prostate cancer

BACKGROUND

Bicalutamide is a nonsteroidal antiandrogen widely used as a first-line clinical treatment for advanced prostate cancer (PCa). Although patients initially show effective responses to bicalutamide treatment, resistance to bicalutamide frequently occurs and leads to the development of castration-resistant PCa (CRPC). This research investigated the roles of the oestrogen receptor α (ERα)-nuclear factor E2-related factor 2 (NRF2) signalling pathway in bicalutamide resistance in PCa cells.

METHODS

We performed bioinformatic analysis and immunohistochemical staining on normal and cancerous prostate tissue to evaluate ERα and NRF2 expression and their correlation. Gene expression and localization in PCa cell lines were further investigated using real-time reverse transcription PCR/Western blotting and immunofluorescence staining. We treated PCa cells with the ER inhibitor tamoxifen and performed luciferase reporter assays and chromatin immunoprecipitation (ChIP) assays to understand ERα-dependent NRF2 expression. Overexpression and knockdown of ERα and NRF2 were used to explore the potential role of the ERα-NRF2 signalling axis in bicalutamide resistance in PCa cells.

RESULTS

We found that the expression of ERα and NRF2 was positively correlated and was higher in human CRPC tissues than in primary PCa tissues. Treatment with oestrogen or bicalutamide increased the expression of ERα and NRF2 as well as NRF2 target genes in PCa cell lines. These effects were blocked by pretreatment with tamoxifen. ChIP assays demonstrated that ERα directly binds to the oestrogen response element (ERE) in the NRF2 promoter. This binding led to increased transcriptional activity of NRF2 in a luciferase reporter assay. Activation of the ERα-NRF2 signalling axis increased the expression of bicalutamide resistance-related genes. Inhibition of this signalling axis by knockdown of ERα or NRF2 downregulated the expression of bicalutamide resistance-related genes and inhibited the proliferation and migration of PCa cells.

CONCLUSIONS

We demonstrated the transcriptional interaction between ERα and NRF2 in CRPC tissues and cell lines by showing the direct binding of ERα to the ERE in the NRF2 promoter under oestrogen treatment. Activation of the ERα-NRF2 signalling axis contributes to bicalutamide resistance in PCa cells, suggesting that the ERα-NRF2 signalling axis is a potential therapeutic target for CRPC. Video Abstract.

Decreased mitophagy aggravates benign prostatic hyperplasia in aged mice through DRP1 and estrogen receptor α

Benign prostatic hyperplasia (BPH) is an age-related disease, whose etiology largely remains unclear. The regulation of mitophagy plays a key role in aging and associated diseases, however, its function in BPH has not been studied. Although the expression of the androgen receptor is primarily implicated in BPH, the estrogen receptor (ER) has been reported to be involved in the development of BPH by mediating the proliferation of prostate cells. Here, we studied the involvement of mitophagy and ERs in spontaneous BPH in aging mice and investigated their functions. To identify the activation of mitophagy and expression of ERs, 8-week, 12-month, and 24-month-old mice were used. Mice were treated with mitochondrial division inhibitor mdivi-1, a dynamin-related protein 1 (Drp1) inhibitor, to examine the expression of mitophagy-related proteins and the development of BPH. In addition, prostate stromal cells were treated with an ER antagonist to investigate the regulation of mitophagy following the expression of ERs. With aging, the Drp1 and phosphorylation of parkin reduce. Electron microscopy revealed reduced mitochondrial fission and mitophagy. In addition, the expression of androgen receptor was decreased and that of ERα was increased in aged mice with BPH. Treatment with mdivi-1 exacerbated BPH and increased cell proliferation. In addition, blockade of ERα increased mitophagy and decreased cell proliferation. In conclusion, mitophagy is reduced with aging during the development of BPH. We speculate that spontaneous BPH progresses through the reduction in the expression of ERα in aged mice by downregulating mitophagy.

Proliferative and Apoptotic Pathways in the Testis of Quail Coturnix coturnix during the Seasonal Reproductive Cycle

Simple Summary

The quail Coturnix coturnix exhibits an annual cycle of testis size, sexual steroid production, and spermatogenesis. The testicular levels of both 17β-estradiol (E₂) and androgens are higher during the reproductive period compared to the non-reproductive period, suggesting that estrogens act in synergy with the androgens for the initiation of spermatogenesis. Therefore, the present study aimed to investigate the estrogen responsive system in quail testis in relation to the reproduction seasons, with a focus on the molecular pathways activated in both active and regressive quail testes. The results indicated that estrogens participated in the activation of mitotic and meiotic events during the reproductive period by activating the ERK1/2 and Akt-1 pathways. In the non-reproductive period, when the E₂/ERα levels are low, ERK1/2 and Akt-1 pathways remain inactive and apoptotic events occur. Our results suggest that the activation or inhibition of these molecular pathways plays a crucial role in the physiological switch “on/off” of the testicular activity in male quail during the seasonal reproductive cycle.

Abstract

The quail Coturnix coturnix is a seasonal breeding species, with the annual reproductive cycle of its testes comprising an activation phase and a regression phase. Our previous results have proven that the testicular levels of both 17β-estradiol (E₂) and androgens are higher during the reproductive period compared to the non-reproductive period, which led us to hypothesize that estrogens and androgens may act synergistically to initiate spermatogenesis. The present study was, therefore, aimed to investigate the estrogen responsive system in quail testis in relation to the reproduction seasonality, with a focus on the molecular pathways elicited in both active and regressive quail testes. Western blotting and immunohistochemistry analysis revealed that the expression of ERα, which is the predominant form of estrogen receptors in quail testis, was correlated with E₂ concentration, suggesting that increased levels of E₂-induced ERα could play a key role in the resumption of spermatogenesis during the reproductive period, when both PCNA and SYCP3, the mitotic and meiotic markers, respectively, were also increased. In the reproductive period we also found the activation of the ERK1/2 and Akt-1 kinase pathways and an increase in second messengers cAMP and cGMP levels. In the non-reproductive phase, when the E2/ERα levels were low, the inactivation of ERK1/2 and Akt-1 pathways favored apoptotic events due to an increase in the levels of Bax and cytochrome C, with a consequent regression of the gonad.

Resveratrol Attenuates the Proliferation of Prostatic Stromal Cells in Benign Prostatic Hyperplasia by Regulating Cell Cycle Progression, Apoptosis, Signaling Pathways, BPH Markers, and NF- κB Activity

Resveratrol can inhibit cell proliferation and metastasis and induce apoptosis. However, the mechanisms of action through which resveratrol inhibits the abnormal proliferation of prostate stromal cells, causing prostatic hyperplasia, have not been fully elucidated. Here, we evaluated the inhibitory effects of resveratrol on cell proliferation associated with prostatic hyperplasia using WPMY-1 cells. Our results showed that resveratrol inhibited the proliferation of WPMY-1 cells via the induction of G₀/G₁-phase cell cycle arrest, which was caused by downregulated expression of cyclins and cyclin-dependent kinases regulated by increased p21WAF1 and p27KIP1 expression level. In addition, resveratrol treatment suppressed the phosphorylation of phosphatidylinositol 3-kinase/AKT and extracellular signal-regulated kinase 1/2. The expression levels of molecular markers affecting prostate development were also reduced by treatment with resveratrol. Finally, resveratrol attenuated the binding activity of the transcription factor nuclear factor-κB in WPMY-1 cells, and accelerated apoptotic cell death via intrinsic cascade pathway. These results indicate that resveratrol may be useful for the prevention or treatment of prostatic hyperplasia.

Immunomodulatory effect of diallyl sulfide on experimentally-induced benign prostate hyperplasia via the suppression of CD4+T/IL-17 and TGF-β1/ERK pathways

Benign prostatic hyperplasia (BPH) is a nonmalignant enlargement of the prostate common in older men. Diallyl sulfide (DAS), a major component of garlic, has been reported to possess antioxidant, anti-inflammatory, and antiproliferative effects. However, the underlying protective immunomodulatory mechanism of DAS on BPH remains vague. Herein, experimental BPH was induced in rats by daily subcutaneous injection of testosterone propionate (TP) (3 mg/kg, s.c.) for 4 weeks. In parallel, finasteride (Fin) (5 mg/kg, p.o) or DAS (50 mg/kg, p.o.) was administered orally during BPH induction. TP-induced histological alterations and the immune-inflammatory cascade. On the other hand, DAS or Fin administration alleviated all abnormalities induced testosterone. Fin and DAS administration markedly reduced prostate weight by 53% with Fin, and by 60% with DAS. Moreover, serum testosterone and DHT were reduced by 55% and 52%, respectively, with Fin and by 68% and 75%, respectively, with DAS, in concordance with decreased protein expression of androgen receptor (AR), and prostate-specific antigen (PSA). Furthermore, both regime lessen immune-inflammatory milieu, as evidenced by decrease CD4+ T-cells protein expression and associated inflammatory cytokines. Concomitantly, Fin and DAS exhibited marked mitigation in insulin-like growth factor-1 (IGF-1), transforming growth factor-beta1 (TGF-β1), and phosphorylated extracellular signal-regulated kinase (ERK1/2) signaling. Besides alleviating oxidative stress by 53% and 68% in prostatic MDA and by 27% and 7% in prostatic iNOS with Fin and DAS, respectively. In conclusion, this work highlighted a potential therapeutic approach of DAS as a dietary preventive agent against BPH via its anti-inflammatory and immunomodulatory effect along with suppression of the ERK pathway.

Pao Pereira Extract Attenuates Testosterone-Induced Benign Prostatic Hyperplasia in Rats by inhibiting 5α-Reductase

Benign prostatic hyperplasia (BPH) is one of the most common diseases in the urinary system of elderly men. Pao extract is an herbal preparation of the bark of the Amazon rainforest tree Pao Pereira (Geissospermum vellosii), which was reported to inhibit prostate cancer cell proliferation. Herein we investigated the therapeutic potential of Pao extract against BPH development in a testosterone-induced BPH rat model. The administration of testosterone induced the prostate enlargement, compared with the sham operated group with vehicle treatment. The BPH/Pao group showed reduced prostate weight comparable with BPH/finasteride group. Notably, Pao treatment did not significantly reduce body weights and sperm number of rats, compared with the control group. Furthermore, Pao extract treatment reduced the proliferative index in prostate glands and testosterone-induced expression levels of AR, as well as androgen-associated proteins such as SRD5A1 and PSA. Moreover, Pao extract and its active component, flavopereirine, induced cytotoxicity on human prostate epithelial RWPE-1 cells in a dose- and time- dependent manner with G2/M arrest. Consistently, Pao extract and flavopereirine suppressed the expression levels of SRD5A1, AR and PSA, respectively. Together, these data demonstrated that Pao extract suppresses testosterone-induced BPH development through inhibiting AR activity and expression, and suggested that Pao extract may be a promising and relative safe agent for BPH.

Aromatase-induced endogenous estrogen promotes tumour metastasis through estrogen receptor-α/matrix metalloproteinase 12 axis activation in castration-resistant prostate cancer

Castration-resistant prostate cancer (CRPC) following androgen deprivation therapy remains a major obstacle advanced prostate cancer management. Aromatase catalyzes estrogen from androgens, yet the role of aromatase-generated endogenous estrogen in CRPC is poorly understood. In this study, we assessed the expression and function of aromatase in CRPC. We found that aromatase expression was significantly increased in CRPC tissues and cell lines. In some prostate cancer cell lines, aromatase was predominantly expressed in CD44⁺ subsets. Bicalutamide treatment significantly increased aromatase expression, and CYP19A1 expression positively correlated with estrogen responses and epithelial-mesenchymal transition. Aromatase knockdown in PC3 cells reduced invasiveness and decreased metastasis-related gene expression. The aromatase inhibitor, letrozole, attenuated tumour metastasis in castrated PC3-xenograft mice. Mechanistically, aromatase-induced endogenous estrogen promoted estrogen receptor-α (ERα) binding to matrix metalloproteinase 12 (MMP12) promoter estrogen response element (ERE). MMP12 co-localized with CD44 on the cell membrane and MMP12 knockdown significantly reduced estradiol-induced PC3 invasion. Taken together, our findings indicated that increased endogenous estrogen, catalysed by elevated aromatase levels, enhanced MMP12 expression via ERα, participated in CRPC progression and promoted tumour metastasis. Thus, aromatase represents a potential novel therapeutic target for CRPC.

Cynomorium songaricum Rupr demonstrates phytoestrogenic or phytoandrogenic like activities that attenuates benign prostatic hyperplasia via regulating steroid 5-α-reductase

ETHNOPHARMACOLOGICAL RELEVANCE

Cynomorium songaricum Rupr. (CS) belongs to the genus of parasitic perennial flowering plants, mostly used in Chinese traditional medicine for benign prostatic hyperplasia (BPH) treatment. BPH is a chronic disease in men that both androgen and estrogen play a crucial role in promoting its development via their receptors. Previously we have showed that compounds from CS have the phytoestrogenic and/or phytoandrogenic activities that may have the potential suppressive effects on BPH, while the mechanism remains unclear.

AIM OF THE STUDY

In this study, we aim to investigate the effect of CS and its derived compounds: luteolin (LUT), gallic acid (GA), protocatechuic acid (PA) and protocatechualdehyde (Pra) on inhibition of rat BPH and proliferation of BPH-1 cell line respectively, and further uncover whether it is related with the phytoestrogenic and / or phytoandrogenic activities.

MATERIALS AND METHODS

Estradiol/testosterone (1:100) was subcutaneous injected to induce BPH in a castrated rat model, and CS was orally administrated for 45 days. Then the weights of the body and prostate were recorded, the pathogenesis changes of prostate were analyzed by Hematoxylin and eosin (H&E) and immunohistochemical (IHC). The levels of 17β-estradiol (E₂), testosterone, and dihydrotestosterone (DHT) from rats' serum were measured by enzyme-linked immunosorbent assay (ELISA). In vitro, human benign prostatic epithelial cell BPH-1 was cultured and treated with or without different CS compounds and DHT or E₂. MTT and CCK-8 assays were performed to detect the regulatory effects on cell proliferation. The expressions of PCNA, AR, ERα, ERβ, and steroid 5-α-reductases (SRD5A1 and SRD5A2) were further analyzed by western blotting upon treatment.

RESULTS

Treatment with CS significantly inhibited rat prostate enlargement, improved the pathological feature and reduced the thickness of smooth muscle layer. The up-regulated AR and ERα expressions and down-regulated ERβ in BPH rat prostate were significantly blocked after CS administration. Moreover, the enhanced values of E₂/testosterone and the level of DHT in serum were also strongly inhibited in CS group compared with those in BPH groups. In cellular level, LUT, GA, PA, or Pra significantly inhibited DHT- or E₂- induced BPH-1 cell proliferation and PCNA expressions. Consistently with the data in vivo, compounds from CS interfered the DHT or E₂-regulated AR, ERα and ERβ expressions in BPH-1 cells as well. Importantly, the dramatic increased SRD5A1 and SRD5A2 expressions were observed in BPH rat prostates and DHT or E₂-stimulated BPH-1 cells. However, treatment with CS in rat or with compounds isolated from CS in BPH-1 cells significantly blocked the induction of SRD5A1 and SRD5A2.

CONCLUSIONS

CS suppressed BPH development through interfering with prostatic AR, ERα/β, and SRD5A1/2 expressions, which provided evidence of CS for BPH treatment.

Roles of ERK1/2 and PI3K/AKT signaling pathways in mitochondria-mediated apoptosis in testes of hypothyroid rats

The absence of the thyroid hormone (TH) could impair testicular function, but its mechanism is still rudimentary. This study aims to explore the roles of estrogen receptor (ER α, β) and G protein-coupled receptor 30 (GPR30), extracellular signal regulated kinase (ERK1/2) and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathways in apoptosis in testes of hypothyroidism rats. Male Wistar rats were randomly divided into control (C), low-(L) and high-hypothyroidism (H) groups [1 mL per 100 g BW per day normal saline, 0.001% and 0.1% propylthiouracil (PTU), respectively] by intragastrical gavage for 60 days. The levels of triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) in serum were measured. Expressions of ERα, ERβ and GPR30, pathway related protein expressions of ERK1/2 and PI3 K/AKT and apoptosis were detected in testicular homogenates. The results showed that T3 and T4 levels were decreased, and the TSH level was increased significantly in the H group. Protein expressions of ERα, ERβ and GPR30 decreased significantly in the H group. Significantly decreased protein expressions of p-ERK1/2, p-PI3K p85, p-AKT Ser473, Ras, p-Raf-1 Ser259, p-Raf-1 Ser338 and cyclin D1 in L and H groups as well PI3K p85, p-AKT and Thr308 in the H group were observed. Moreover, there was a significant increase in the Bad protein expression in L and H groups. In addition, there was a significant increase in the expression of Bax/Bcl-2, caspase 9 and cleaved caspase 3 and a significant decrease in the total caspase 3 protein expression in the H group. These results suggested that ERK1/2 and PI3K/AKT signaling pathways could be suppressed by hypothyroidism via inhibiting the expressions of ERs and could finally induce apoptosis in testes.

Comparative Analysis of the Effects of 17-Beta Estradiol on Proliferation, and Apoptosis in Hepatocellular Carcinoma Hep G2 and LCL-PI 11 Cell Lines

Background:

Phytoestrogens are a group of natural compounds with estrogen-like activity and similar structure to estradiol that structurally mimic the mammalian estrogen 17-β estradiol (E2). They have a biphasic effect and exert pleiotropic effects which induce or inhibit estrogen action by activation/inhibition of the estrogen receptors (ERs). These compounds can induce apoptosis at high concentrations. The previous finding indicated that E2 inhibited cell growth and induced apoptosis in hepatocellular carcinoma (HCC) PLC/PRF/5 cell line. The aim of the present study was to investigate the apoptotic and proliferative effects of E2 on hepatocellular carcinoma HepG 2 and LCL-PI 11 cells.

Methods:

The Hep G2 and LCL-PI 11 cells were cultured and treated with E2 for different time periods and then MTT [3-(4, 5-dimethyl-2-thiazolyl) -2, 5-diphenyl -2H- tetrazolium bromide] assay and flow cytometry assay were done to determine cell viability and cell apoptosis respectively.

Results:

E2 had inhibitory and apoptotic effects on Hep G2 cell line, whereas it indicated a biphasic effect on LCL-PI 11 cell line. The half-maximum inhibitory concentration (IC50) value was 3 μM. The inhibitory effect of E2 on Hep G2 cells was observed with all concentrations of E2 (P <0.087), whereas E2 showed a biphasic effect on LCL-PI 11. This compound induced significant apoptosis in Hep G2 cell line at the all treatment times versus control groups, whereas, in the LCL-PI 11 cell, significant apoptotic cells were observed after 72 and 96h (P <0.001).

Conclusion:

E2 can inhibit cell growth and induce apoptosis in hepatocellular carcinoma HepG 2 and LCL-PI 11 cell lines.

Berberine Improves Benign Prostatic Hyperplasia via Suppression of 5 Alpha Reductase and Extracellular Signal-Regulated Kinase in Vivo and in Vitro

Benign prostate hyperplasia (BPH) is a common disease in elderly men, characterized by proliferated prostate and urinary tract symptoms. The hormonal cascade starting by the action of 5-alpha-reductase (5AR) is known to be one of the pathways responsible for the pathogenesis of BPH. Present investigation evaluated the capacity of berberine (BBR), a nature-derived compound abundant in Coptis japonica, in testosterone-induced BPH rats. Experimental BPH was induced by inguinal injection with testosterone propionate (TP) for 4 weeks. BBR or finasteride, a 5AR inhibitor as positive control, was treated for 4 weeks during BPH. BPH induced by TP evoked weight gaining and histological changes of prostate and BBR treatment improved all the detrimental effects not only weight reduction and histological changes but also suppression of prostate-specific antigen (PSA), which is elevated during BPH. Additionally, BBR suppressed TP-associated increase of 5AR, androgen receptor (AR) and steroid coactivator-1 (SRC-1), the key factors in the pathogenesis of BPH. To evaluate the underlying molecular mechanisms responsible for beneficial effects of BBR, we investigated whether these effects were associated with the mitogen-activated protein kinase pathway. BPH induced by TP showed increased phosphorylation of extracellular signal-regulated kinase (ERK), whereas this was suppressed by BBR treatment. On the other hand, c-jun-N-terminal kinase (JNK) and p38 mitogen-activated protein kinase was not changed in BPH rats. In in vitro study using RWPE-1 cells, a human prostate epithelial cell line. TP increased cell proliferation and BPH-related key factors such as PSA, AR, and 5AR in RWPE-1 cells, and those factors were significantly decreased in the presence of BBR. Furthermore, these proliferative effects in RWPE-1cells were attenuated by treatment with U0126, an ERK inhibitor, confirming BBR can relieve overgrowth of prostate via ERK-dependent signaling. The cotreatment of U0126 and BBR did not affect the change of 5AR nor proliferation compared with U0126 alone, suggesting that the effect of BBR was dependent on the action of ERK. In conclusion, this study shows that BBR can be used as a therapeutic agent for BPH by controlling hyperplasia of prostate through suppression of ERK mechanism.

Effect of Genistein and 17-β Estradiol on the Viability and Apoptosis of Human Hepatocellular Carcinoma HepG2 cell line

Background:

One of the most lethal cancers is hepatocellular carcinoma (HCC). Genistein (GE) is a choice compound for treatment of certain types of cancer. Phytoestrogens are plant derivatives that bear a structural similarity to 17-β estradiol (E2) and act in a similar manner. They are a group of lipophillic plant compounds with tumorigenic and antitumorigenic effects. E2 has stimulatory and inhibitory effects on cancer cell lines. This study was designed to investigate the antiproliferative and apoptotic effects of GE and E2 on the HCC HepG2 cell line.

Materials and Methods:

HepG2 cells were cultured and treated with various concentrations of GE and E2 and then 3-[4, 5-dimethyl-2-thiazolyl]-2, 5-diphenyl-2H-tetrazolium bromideand flow cytometry assay were performed to determine cell viability and apoptosis.

Results:

GE and E2 induced apoptosis and inhibited cell growth significantly. Reduction of cell viability by 50% required 20 μM E2 for E2-treatment groups and 20 μMGE for GE-treatment groups. The percentage of the GE-treated apoptotic cells was reduced by about 35%, 42%, and 47% (P < 0.001) and that of E2-treated groups 34%, 39%, and 42% (P < 0.001) after 24, 48, and 72 h, respectively.

Conclusions:

Our experimental work clearly demonstrated that GE and E2 exhibited significant antiproliferative and apoptotic effects on human HCC HepG2 cells.

Estradiol promotes epithelial-to-mesenchymal transition in human benign prostatic epithelial cells

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) is involved in pathogenesis of human benign prostatic hyperplasia (BPH). Estrogenic signaling pathways may stimulate the induction of EMT. However, the details of estradiol (E2) and estrogen receptors (ERs) effects on EMT, as well as E2-induced modulation of benign prostatic epithelial cell phenotype in vitro have not been completely clarified.

METHODS

The effects of E2 on EMT markers and cytokeratins (CKs) expression were evaluated in benign epithelial cell lines BPH-1 and RWPE-1, which were cultured both in two-dimensional (2D) culture and three-dimensional (3D) culture model using hanging drop technique or 3D Matrigel model. ER antagonist, ICI182,780, was used to confirm the regulatory effects of E2 on EMT and phenotypic modulation. In 3D culture, immunohistochemical stainings were performed to detect the specific phenotype of cells that underwent EMT in acinar-like spheroids formed by RWPE-1. To illustrate the exact function of ERs in E2-induced EMT and phenotypic modulation, specific short interfering RNAs (siRNAs), and agonists were used to knockdown or activate individual ERs, respectively.

RESULTS

E2-induced EMT was observed both in 2D and 3D culture, with related regulation of EMT markers expression at both mRNA and protein level. In addition, E2 down-regulated luminal cell type markers CK18 and CK8 and up-regulated basal cell type markers CK5 and CK14. E2 also increased intermediate type markers CK15 and CK17, while it attenuated CK19 in 3D culture. ICI182,780 blocked E2-induced EMT and cell phenotypic switching. In 3D Matrigel culture, Vimentin was co-expressed with ERα and CK17, as well as with SMemb, which is related to cell status switching and proliferation. Knockdown of ERα but not GPR30 inhibited EMT, while ERβ knockdown facilitated EMT process. Knockdown of ERα blocked E2-induced EMT both in RWPE-1 and BPH-1. MRNA expression of EMT markers was stimulated by ERα-specific agonist PPT and inhibited by ERβ-specific agonist DPN.

CONCLUSIONS

Estrogenic effect mediated by ERα can promote EMT. E2 is also an inductive factor of cell phenotypic switching. Cell type modulation is associated with E2-induced EMT in benign prostatic epithelial cells. Taken together the results support a contribution of estrogens to the pathogenesis of BPH in elderly men.

Compounds from Cynomorium songaricum with Estrogenic and Androgenic Activities Suppress the Oestrogen/Androgen-Induced BPH Process

Objective

To investigate the phytoestrogenic and phytoandrogenic activities of compounds isolated from CS and uncover the role of CS in prevention of oestrogen/androgen-induced BPH.

Methods

Cells were treated with CS compounds, and immunofluorescence assay was performed to detect the nuclear translocation of ERα or AR in MCF-7 or LNCaP cells; luciferase reporter assay was performed to detect ERs or AR transcriptional activity in HeLa or AD293 cells; MTT assay was performed to detect the cell proliferation of MCF-7 or LNCaP cells. Oestrogen/androgen-induced BPH model was established in rat and the anti-BPH, anti-estrogenic, and anti-androgenic activities of CS in vivo were further investigated.

Results

The nuclear translocation of ERα was stimulated by nine CS compounds, three of which also stimulated AR translocation. The transcriptional activities of ERα and ERβ were induced by five compounds, within which only ECG induced AR transcriptional activity as well. Besides, ECG stimulated the proliferation of both MCF-7 cells and LNCaP cells. CS extract suppressed oestrogen/androgen-induced BPH progress in vivo by downregulation of E2 and T level in serum and alteration of the expressions of ERα, ERβ, and AR in the prostate.

Conclusion

Our data demonstrates that compounds from CS exhibit phytoestrogenic and phytoandrogenic activities, which may contribute to inhibiting the oestrogen/androgen-induced BPH development.

Role of GPR30 in estrogen-induced prostate epithelial apoptosis and benign prostatic hyperplasia

Several studies have implicated estrogen and the estrogen receptor (ER) in the pathogenesis of benign prostatic hyperplasia (BPH); however, the mechanism underlying this effect remains elusive. In the present study, we demonstrated that estrogen (17β-estradiol, or E2)-induced activation of the G protein-coupled receptor 30 (GPR30) triggered Ca²⁺ release from the endoplasmic reticulum, increased the mitochondrial Ca²⁺ concentration, and thus induced prostate epithelial cell (PEC) apoptosis. Both E2 and the GPR30-specific agonist G1 induced a transient intracellular Ca²⁺ release in PECs via the phospholipase C (PLC)-inositol 1, 4, 5-triphosphate (IP₃) pathway, and this was abolished by treatment with the GPR30 antagonist G15. The release of cytochrome c and activation of caspase-3 in response to GPR30 activation were observed. Data generated from the analysis of animal models and human clinical samples indicate that treatment with the GPR30 agonist relieves testosterone propionate (TP)-induced prostatic epithelial hyperplasia, and that the abundance of GPR30 is negatively associated with prostate volume. On the basis of these results, we propose a novel regulatory mechanism whereby estrogen induces the apoptosis of PECs via GPR30 activation. Inhibition of this activation is predicted to lead to abnormal PEC accumulation, and to thereby contribute to BPH pathogenesis.

GPER-novel membrane oestrogen receptor

The recent discovery of the G protein-coupled oestrogen receptor (GPER) presents new challenges and opportunities for understanding the physiology, pathophysiology and pharmacology of many diseases. This review will focus on the expression and function of GPER in hypertension, kidney disease, atherosclerosis, vascular remodelling, heart failure, reproduction, metabolic disorders, cancer, environmental health and menopause. Furthermore, this review will highlight the potential of GPER as a therapeutic target.

Rs4265085 in GPER1 gene increases the risk for unexplained recurrent spontaneous abortion in Dai and Bai ethnic groups in China

Oestrogen receptors are implicated in the pathogenesis of recurrent spontaneous abortion (RSA). Non-genomic oestrogen responses can be mediated by GPER. The prevalence of polymorphisms in GPER1 gene in RSA was assessed in 747 Chinese women from Yunnan province (171 Bai, 258 Chinese Han, 234 Dai, 33 Achang and 51 Jingpo patients). Snapshot technology was used for genotyping the polymorphisms of the GPER1 gene. The rs4265085G was significantly increased in the Dai and Bai groups versus controls (Dai: P < 0.0001, P_adj < 0.0001, OR 95% CI 2.34 [1.79 to 3.05]; Bai: P = 0.0004, P_adj = 0.0012, OR 95% CI 1.71 [1.27 to 2.31]); recessive model of rs4265085 in the Dai (P = 0.003, P_adj = 0.009, OR 95% CI 2.71 [1.38 to 5.30]); Bai (P < 0.0001, P_adj < 0.0001, OR 95% CI 3.37 [1.93 to 5.91]). Haplotype frequencies containing rs10269151G-rs4265085G-rs11544331C were separately significantly different in Dai and Bai ethnic groups (Dai: P = 0.0002, P_adj = 0.001, OR 95% CI = 2.12 [1.43 to 3.17]; Bai: P = 0.005, P_adj = 0.025, OR 95% CI = 1.82 [1.18 to 2.78]) compared with controls. The intron variant rs4265085 may confer risk for RSA in Dai and Bai ethnic groups.

Effects of Transdermal Testosterone Gel or an Aromatase Inhibitor on Prostate Volume in Older Men

CONTEXT

T replacement is being increasingly offered to older men with age-related low T; hence, monitoring prostate health is important during T therapy. Data suggest that estrogens have an independent effect on the prostate and some effects of T on the prostate might be mediated via its aromatization to estradiol. Although some studies have assessed the effects of T replacement on prostate volume, the differential effects of T and estradiol have not been delineated.

OBJECTIVE

The objective of the study was to investigate the relative effects of T and estradiol on prostate volume in older men with low T.

PARTICIPANTS

Thirty-one men, 65 years old or older with total T less than 350 ng/dL (measured by mass spectrometry) participated in the study.

INTERVENTION

The intervention included randomization to 5 g transdermal T gel (TT), 1 mg oral aromatase inhibitor (AI), or placebo daily for 12 months.

MAIN OUTCOME MEASURES

The primary outcome was prostate volume measured by transrectal ultrasound at baseline and 12 months. Secondary outcomes included prostate-specific antigen levels and lower urinary tract symptoms score.

RESULTS

Serum T levels increased in both intervention groups; estradiol levels increased in the TT group, whereas it decreased in the AI group. At 12 months, prostate volume significantly increased (4.5 ± 1.76 cc, P < .05) only in the TT group. Increase in prostate-specific antigen levels were seen in both intervention groups at 6 months (P < .01 and P < .001). The lower urinary tract symptoms score increased only in the TT group (P < .05).

CONCLUSIONS

The tropic effects of T on the prostate are mediated via its aromatization to estradiol. Administration of AI for 12 months to older men was not detrimental to the prostate.

The therapeutic effects of docosahexaenoic acid on oestrogen/androgen-induced benign prostatic hyperplasia in rats

Benign prostatic hyperplasia (BPH) is one of the major disorders of the urinary system in elderly men. Docosahexaenoic acid (DHA) is the main component of n-3 polyunsaturated fatty acids (n-3 PUFAs) and has nerve protective, anti-inflammatory and tumour-growth inhibitory effects. Here, the therapeutic potential of DHA in treating BPH was investigated. Seal oil effectively prevented the development of prostatic hyperplasia induced by oestradiol/testosterone in a rat model by suppressing the increase of the prostatic index (PI), reducing the thickness of the peri-glandular smooth muscle layer, inhibiting the proliferation of both prostate epithelial and stromal cells, and downregulating the expression of androgen receptor (AR) and oestrogen receptor α (ERα). An in vitro study showed that DHA inhibited the growth of the human prostate stromal cell line WPMY-1 and the epithelial cell line RWPE-1 in a dose- and time-dependent manner. In both cell lines, the DHA arrested the cell cycle in the G2/M phase. In addition, DHA also reduced the expression of ERα and AR in the WPMY-1 and RWPE-1 cells. These results indicate that DHA inhibits the multiplication of prostate stromal and epithelial cells through a mechanism that may involve cell cycle arrest and the downregulation of ERα and AR expression.

The prevention and treatment effects of tanshinone IIA on oestrogen/androgen-induced benign prostatic hyperplasia in rats

Benign prostatic hyperplasia (BPH) is one of the major diseases of the urinary system in elderly men. Tanshinone IIA (Tan IIA) is the active ingredient extracted from the traditional Chinese medicine Salvia, and it has effects of anti-oxidation, anti-inflammation, vascular smooth muscle relaxation and tumour growth inhibition. The present study aimed to investigate the therapeutic potential of Tan IIA in the prevention and treatment of BPH. In a rat model of oestradiol/testosterone-induced BPH, Tan IIA inhibited the increase in the thickness of the peri-glandular smooth muscle layer, suppressed the expression of proliferating cell nuclear antigen (PCNA) in both prostate epithelial cells and stromal cells, downregulated the expression of androgen receptor (AR), oestrogen receptor α (ERα), cyclin B1 (CCNB1) and cyclin D1 (CCND1), and effectively prevented the development of the disorder. In vitro, Tan IIA inhibited the proliferation of human prostate stromal cell line WPMY-1 and epithelial cell line RWPE-1 in a dose- and time-dependent manner. In WPMY-1 cells, Tan IIA treatment arrested the cell cycle at the G2/M phase and downregulated the expression of CCNB1. However, in RWPE-1 cells, Tan IIA treatment arrested cell cycle at the G0/G1 phase and reduced the expression of CCND1. Tan IIA also reduced the expression of ERα and AR in WPMY-1 and RWPE-1 cells. These results suggest that Tan IIA can inhibit the growth of prostate stromal and epithelial cells both in vivo and in vitro by a mechanism that may involve arresting the cell cycle and downregulating ERα and AR expression.

MicroRNAs 143 and 145 may be involved in benign prostatic hyperplasia pathogenesis through regulation of target genes and proteins

OBJECTIVES

The aim of this study was to analyze the roles of miR-143 and miR-145, as well as the gene and protein expression of their targets (KRAS, ERK5, MAP3K3, and MAP4K4) in the pathogenesis of benign prostatic hyperplasia (BPH).

METHODS

We analyzed the specimens of 44 patients diagnosed with BPH who underwent surgical treatment. The control group consisted of prostate samples from 2 young patients who were organ donors. miRNAs and their target genes were assessed using real-time polymerase chain reaction (qRT-PCR), and protein levels were assessed by Western blotting.

RESULTS

miR-143 and miR-145 were overexpressed in, respectively, 62.5% and 73.8% of the cases. The ERK5 and MAP4K4 genes were underexpressed respectively in 59.4% and 100% of the BPH samples, whereas KRAS and MAP3K3 were overexpressed respectively in 79.4% and 61.5% of the samples. Increased protein expression was found for both KRAS (4,312.2 luminance/area) and MAP3K3 (7,461.7 luminance/area), while the ERK5 protein was more abundant in the samples from patients with prostate larger than 60 grams (p=0.019).

CONCLUSIONS

The overexpression of miR-143 and miR-145 in BPH samples suggests an association with the pathogenesis of the disease; additionally, the latter miRNA may act through the inhibition of MAP4K4. KRAS and MAP3K3 overexpression may also be associated with BPH pathogenesis. Further analyses are necessary to confirm these results.

Epithelial-to-mesenchymal transition and estrogen receptor α mediated epithelial dedifferentiation mark the development of benign prostatic hyperplasia

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) has been reported involved in the pathogenesis of fibrotic disorders and associated with stemness characteristics. Recent studies demonstrated that human benign prostatic hyperplasia (BPH) development involves accumulation of mesenchymal-like cells derived from the prostatic epithelium. However, the inductive factors of EMT in the adult prostate and the cause-and-effect relationship between EMT and stemness characteristics are not yet resolved.

METHODS

EMT expression patterns were immunohistochemically identified in the human epithelia of normal/BPH prostate tissue and in a rat BPH model induced by estrogen/androgen (E2/T, ratio 1:100) alone or in the presence of the ER antagonist raloxifene. Gene expression profiles were analyzed in micro-dissected prostatic epithelia of rat stimulated by E2/T for 3 days.

RESULTS

Two main morphological features both accompanied with EMT were observed in the epithelia of human BPH. Luminal cells undergoing EMT dedifferentiated from a cytokeratin (CK) CK18(+) /CK8(+) /CK19(+) to a CK18(-) /CK8(+) /CK19(-) phenotype and CK14 expression increased in basal epithelial cells. ERα expression was closely related to these dedifferentiated cells and the expression of EMT markers. A similar pattern of EMT events was observed in the E2/T induced rat model of BPH in comparison to the prostates of untreated rats, which could be prevented by raloxifene.

CONCLUSIONS

Epithelial and mesenchymal phenotype switching is an important mechanism in the etiology of BPH. ERα mediated enhanced estrogenic effect is a crucial inductive factor of epithelial dedifferentiation giving rise to activation of an EMT program in prostate epithelium.

The expression status of G protein-coupled receptor GPR30 is associated with the clinical characteristics of endometriosis

INTRODUCTION

GPR30 is a seven-transmembrane G protein-coupled estrogen receptor that regulates endometrial cellular responses to estrogen. GPR30 is often highly expressed in cancer cells from aggressive tumors. The aim of this study was to evaluate the expression patterns of GPR30 in endometriosis during medical treatment.

PATIENTS

A total of 38 females, 28 patients with endometriosis and 10 patients with leiomyoma who underwent laparoscopic surgery were included this study.

INTERVENTION

Eutopic endometrial tissue sampling from women without endometriosis and ectopic endometrial tissue sampling from women with endometriosis.

MAIN OUTCOME MEASURE

A quantitative real-time polymerase chain reaction analysis of the mRNA expression in eutopic and ectopic endometrial tissues with or without GnRH agonist treatment. The expression of GPR30 was confirmed by immunohistochemistry.

RESULTS

There was an increased level of GPR30 mRNA in eutopic endometrium during the proliferative phase, whereas higher expression was observed in the ectopic endometrium during the secretory phase. Increased GPR30 mRNA was observed in ectopic endometrium in comparison to eutopic endometrium. GnRH agonist treatment before laparoscopic surgery decreased GPR30 mRNA in ectopic endometrium. The immunohistochemical analysis also revealed that GPR30 was strongly expressed in epithelial cells in ectopic endometrium, whereas GnRH agonist treatment decreased the GPR30 expression.

CONCLUSION

High levels of GPR30 expression can play an important role in the progression of endometriosis.

G protein-coupled estrogen receptor (GPER) expression in normal and abnormal endometrium

Rapid estrogen effects are mediated by membrane receptors, and evidence suggests a role for both a membrane-associated form of estrogen receptor alpha (ESR1; ERα) and G-protein coupled receptor 30 (GPER; GPR30). Considering estrogen's importance in endometrial physiology and endometriosis pathophysiology, we hypothesized that GPER could be involved in both cyclic changes in endometrial estrogen action and that aberrant expression might be seen in the eutopic endometrium of women with endometriosis. Using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemical analysis of normal endometrium, endometrial samples demonstrated cycle-regulated expression of GPER, with maximal expression in the proliferative phase. Eutopic and ectopic endometrium from women with endometriosis overexpressed GPER as compared to eutopic endometrium of normal participants. Ishikawa cells, an adenocarcinoma cell line, expressed GPER, with increased expression upon treatment with estrogen or an ESR1 agonist, but not with a GPER-specific agonist. Decreased expression was seen in Ishikawa cells stably transfected with progesterone receptor A. Together, these data suggest that normal endometrial GPER expression is cyclic and regulated by nuclear estrogen and progesterone receptors, while expression is dysregulated in endometriosis.

Estrogen promotes prostate cancer cell migration via paracrine release of ENO1 from stromal cells

As a key glycolytic enzyme, enolase 1 (ENO1) is critical for cellular energy metabolism. Recent studies have revealed its important role in growth and metastasis of lung, head and neck, and breast cancer. However, the regulatory mechanisms of ENO1 expression and secretion remain unclear. We observed that conditioned medium from estradiol-stimulated prostate stromal cells significantly promoted the migration of prostate cancer (PCa) cells. Two-dimensional protein electrophoresis, mass spectrometry, and immunodepletion assays identified one of the major active factors in the conditioned medium as α-type enolase (α-enolase, or ENO1). Moreover, in prostate stromal cells, estradiol not only enhanced the stability of ENO1 at the protein level in an estrogen receptor-α-dependent manner but also promoted its secretion to the extracellular matrix. Furthermore, recombinant ENO1 bound to the surface of PCa cells and promoted cell migration via their plasminogen receptor activity in a paracrine manner. Immunohistochemistry suggested that stromal ENO1 levels increased in PCa compared with those in normal tissue.

Involvement of estrogen receptors in prostatic diseases

Accumulating evidence shows that estrogens participate in the pathogenesis and development of benign prostatic hyperplasia and prostate cancer by activating estrogen receptor α. In contrast, estrogen receptor β is involved in the differentiation and maturation of prostatic epithelial cells, and thus possesses antitumor effects in prostate cancer. However, the natural ligands of estrogen receptor β are not fully understood, and its mode of action according to its ligands and the binding sites located in the promoter regions of downstream genes remains to be elucidated. Here, we review recent experimental investigations of estrogen receptors and their urological relevance. Estrogen receptor-mediated signaling in the prostate is essential together with the androgen receptor-mediated pathway, providing a new therapeutic target for prostatic diseases.

Estrogens and prostate cancer: etiology, mediators, prevention, and management

The mainstay targets for hormonal prostate cancer (PCa) therapies are based on negating androgen action. Recent epidemiologic and experimental data have pinpointed the key roles of estrogens in PCa development and progression. Racial and geographic differences, as well as age-associated changes, in estrogen synthesis and metabolism contribute significantly to the etiology. This article summarizes how different estrogens/antiestrogens/estrogen mimics contribute to prostate carcinogenesis, the roles of the different mediators of estrogen in the process, and the potentials of new estrogenic/antiestrogenic compounds for prevention and treatment of PCa.

PPARγ: a molecular link between systemic metabolic disease and benign prostate hyperplasia

The emergent epidemic of metabolic syndrome and its complex list of sequelae mandate a more thorough understanding of benign prostatic hyperplasia and lower urinary tract symptoms (BPH/LUTS) in the context of systemic metabolic disease. Here we discuss the nature and origins of BPH, examine its role as a component of LUTS and review retrospective clinical studies that have drawn associations between BPH/LUTS and type II diabetes, inflammation and dyslipidemia. PPARγ signaling, which sits at the nexus of systemic metabolic disease and BPH/LUTS through its regulation of inflammation and insulin resistance, is proposed as a candidate for molecular manipulation in regard to BPH/LUTS. Finally, we introduce new cell and animal models that are being used to study the consequences of obesity, diabetes and inflammation on benign prostatic growth.

Estrogen and androgen signaling in the pathogenesis of BPH

Estrogens and androgens have both been implicated as causes of benign prostatic hyperplasia (BPH). Although epidemiological data on an association between serum androgen concentrations and BPH are inconsistent, it is generally accepted that androgens play a permissive role in BPH pathogenesis. In clinical practice, inhibitors of 5α-reductase (which converts testosterone to the more potent androgen dihydrotestosterone) have proven effective in the management of BPH, confirming an essential role for androgens in BPH pathophysiology. To date, multiple lines of evidence support a role for estrogens in BPH pathogenesis. Studies of the two estrogen receptor (ER) subtypes have shed light on their differential functions in the human prostate; ERα and ERβ have proliferative and antiproliferative effects on prostate cells, respectively. Effects of estrogens on the prostate are associated with multiple mechanisms including apoptosis, aromatase expression and paracrine regulation via prostaglandin E2. Selective estrogen receptor modulators or other agents that can influence intraprostatic estrogen levels might conceivably be potential therapeutic targets for the treatment of BPH.

Effect of combined hormonal and insulin therapy on the steroid hormone receptors and growth factors signalling in diabetic mice prostate

Diabetes causes harmful effects on prostatic morphology and function. However, there still are doubts about the occurrence of various diseases in the prostate, as well as abnormal angiogenesis in relation to diabetes. Thus, the aim of this study was to correlate and quantify the level of the steroid hormone receptors and the angiogenic and antiangiogenic factors in non-obese diabetic mice (Nod) after combined hormonal and insulin therapy. Sixty mice were divided into six groups after 20 days of diabetes: the control group received 0.9% NaCl, as did the diabetic group. The diabetic-insulin group received insulin, the diabetic-testosterone group received testosterone cypionate, the diabetic-oestrogen group received 17β-oestradiol, and the diabetic-insulin-testosterone-oestrogen group received insulin, testosterone and oestrogen simultaneously. After 20 days, the ventral lobe was processed for immunocytochemical and hormonal analyses. The results showed that the lowest serum testosterone and androgen receptor levels were found in the diabetic group and the highest testosterone and androgen receptor levels in the diabetic-insulin-testosterone-oestrogen group. The serum oestrogen level and its receptor showed changes opposite to those of testosterone and its receptor. The endostatin reactivity was mainly decreased in diabetic mice. The greatest IGFR-1 and VEGF reactivities occurred in diabetic mice. Thus, diabetes led to the prostatic hormonal imbalance, affecting molecular dynamics and angiogenesis in this organ. Combined insulin and steroid hormone therapy partially restored the hormonal and angiogenic imbalance caused by diabetes.

G protein-coupled receptor 30 in tumor development

Estrogen plays several important physiological and pathological functions in not only reproductive system but many other systems as well. Its transcriptional activation has been traditionally described as being mediated by classic nuclear estrogen receptors (ERs). It is however established recently that a novel functional estrogen transmembrane receptor, G protein-coupled receptor 30 (GPR30), modulates both rapid non-genomic events and genomic transcriptional events of estrogen. It has been demonstrated that GPR30 promotes the progress of estrogen-related tumors through mitogen-activated protein kinase (MAPK) signaling pathways. Effects mediated by GPR30 are maintained when classic ERs are absent or blocked. In addition, GPR30 is involved in drug resistance, which is often occurring during cancer treatments. All these new findings strongly imply that GPR30 may be an important therapeutic target for estrogen-related tumors. Simultaneously blocking both GPR30 and classic ERs may be a better strategy for the treatment of estrogen-related tumors.

Antagonism of estrogen-mediated cell proliferation by raloxifene in prevention of ageing-related prostatic hyperplasia

Estrogen has important roles in the initiation and development of benign prostatic hyperplasia (BPH). Regulators of the estrogen receptor (ER) are tissue- and cell-specific. We evaluated the effect of estrogen antagonist, raloxifene (Ral), on the prevention and treatment of BPH by investigating its effect on the proliferation of two different prostate cell lines: a stromal cell line, WPMY-1, and a benign prostatic hyperplasia epithelial cell line, BPH-1. We additionally evaluated its effect on prostatic hyperplasia induced by estrogen and androgen in a rat model. The effect of Ral on the prevention of prostatic hyperplasia was analyzed by haematoxylin and eosin staining and quantitative immunohistochemistry (IHC) for proliferating cell nuclear antigen and alpha-smooth muscle actin. In vitro and in vivo, tamoxifen (Tam), another anti-estrogen drug, and finasteride (Fin), a drug for the clinical treatment of BPH, served as efficacy controls. The in vitro data showed that neither Ral nor Tam alone affected the proliferation of WPMY-1 and BPH-1, but both antagonized the effect of oestradiol in promoting the proliferation of the two cells. Results from the IHC staining of the rat prostates indicated that, similar to Tam and Fin, Ral inhibited the proliferation of stromal cells in vivo. Interestingly, in contrast to Tam, both Ral and Fin inhibited the proliferation of epithelial cells. Furthermore, Ral treatment much strongly decreased the number of prostatic acini and the surrounding layers of smooth muscle cells than Fin (P < 0.05). Our data showed for the first time that Ral may have a role in the response of the rat prostate to selective ER modulators.

Both nongenomic and genomic effects are involved in estradiol's enhancing the phenotype of smooth muscle cells in cultured prostate stromal cells

BACKGROUND

Stromal smooth muscle cells (SMCs) play an important role in the pathogenesis and clinical symptom of benign prostatic hyperplasia. We had reported that estrogen enhances the phenotype of SMC in cultured prostate stromal cells (PRSCs). Here we further investigate the mechanism by which estrogen affects the differentiation of PRSCs.

METHODS

Primary cultured PRSCs were stimulated with E2 or BSA-E2. The mRNA level of SMC-specific genes, smoothelin, and SM-MHC were measured by qRT-PCR. The SM-MHC protein was measured by Western blot. The mRNA and protein levels of TGF-beta1 were measured by qRT-PCR and ELISA. The MAPK inhibitor PD98059, the estrogen receptor antagonist ICI182,780 and neutralizing antibody to TGF-beta1 were used to reveal the mechanism of estrogen effect.

RESULTS

E2 and BSA-E2 significantly up-regulate the expression of SMC-specific genes in PRSCs. Both forms of estrogen could increase the expression of TGF-beta1, which can be blocked by pre-treating with PD98059. Moreover, PD98059 and TGF-beta1 neutralizing antibody could abrogate the effect of BSA-E2 on cell differentiation. However, they could only inhibit part of E2-induced SMC phenotype enhancement. ICI182,780 could partially suppress the pro-differentiation effect of E2 but had no influence on the effect of BSA-E2. Combined treatment with ICI182,780 and PD98059 can completely abrogate the effect of E2.

CONCLUSIONS

Estrogen could promote the expression of TGF-beta1 in PRSCs through nongenomic activation of MAPK pathway, and in turn enhance the SMC phenotype. Besides for this nongenomic effect, estrogen can also enhance the SMC phenotype through classical genomic action.

Estrogen receptors and function in the male reproductive system

A substantial advance in our understanding on the estrogen signaling occurred in the last decade. Estrogens interact with two receptors, ESR1 and ESR2, also known as ERα and ERβ, respectively. ESR1 and ESR2 belong to the nuclear receptor family of transcription factors. In addition to the well established transcriptional effects, estrogens can mediate rapid signaling, triggered within seconds or minutes. These rapid effects can be mediated by ESRs or the G protein-coupled estrogen receptor GPER, also known as GPR30. The effects of estrogen on cell proliferation, differentiation and apoptosis are often mediated by growth factors. The understanding of the cross-talk between androgen, estrogen and growth factors signaling pathways is therefore essential to understand the physiopathological mechanisms of estrogen action. In this review we focused on recent discoveries about the nature of the estrogen receptors, and on the signaling and function of estrogen in the male reproductive system.

Icaritin induces growth inhibition and apoptosis of human prostatic smooth muscle cells in an estrogen receptor-independent manner

Icaritin has selective estrogen receptor (ER) modulating activity. ERs are expressed in the prostate stroma, and estrogens have an important role in the pathology of benign prostatic hyperplasia (BPH). However, the impact of icaritin on BPH was not studied. Human prostatic smooth muscle cells (PSMCs) were treated with 0-100 microM icaritin, also using 10 microM ICI182780 as a specific ER antagonist. The effects on cell growth and apoptosis were determined by cell counting and sandwich-enzyme-immunoassay. Western blotting was employed to illustrate the possible mechanisms. Cell growth was strongly inhibited by icaritin, and this was accompanied by an augmented apoptosis. Few changes in icaritin-induced growth inhibition and apoptosis were observed after pretreatment in the presence of ICI182780. Consistent with growth inhibition and apoptosis induction, icaritin decreased cyclin D1 and CDK4 expression and increased Bax/Bcl-2 ratio in human PSMCs. Furthermore, icaritin induced sustained phosphorylation of extracellular signal-regulated kinase (ERK) in human PSMCs. PD98059, a specific ERK inhibitor, blocked the activation of ERK by icaritin and abolished the icaritin-induced growth inhibition and apoptosis. The results indicate that icaritin reduces growth and induces apoptosis in human PSMCs via ERK signaling pathway without involvement of ERs.

17Beta-estradiol at low concentrations acts through distinct pathways in normal versus benign prostatic hyperplasia-derived prostate stromal cells

The aim of this study was to identify differential responses to low concentrations of 17beta-estradiol (E2) in primary stromal cell cultures derived from either normal organ donors or benign prostatic hyperplasia or hypertrophy (BPH) specimens. Furthermore, we sought to identify the potential mechanism of E2 action in these cell types, through either a genomic or nongenomic mechanism. We initially treated stromal cells derived from five normal prostates or five BPH specimens with low concentrations of E2 (0.001-1.0 nM) and analyzed their growth response. To determine whether genomic or nongenomic pathways were involved, we performed studies using specific estrogen receptor antagonists to confirm transcriptional activity or MAPK inhibitors to confirm the involvement of rapid signaling. Results of these studies revealed a fundamental difference in the mechanism of the response to E2. In normal cells, we found that a nongenomic, rapid E2 signaling pathway is predominantly involved, mediated by G protein-coupled receptor-30 and the subsequent activation of ERK1/2. In BPH-derived prostate stromal cells, a genomic pathway is predominantly involved because the addition of ICI 182780 was sufficient to abrogate any estrogenic effects. In conclusion, prostate stromal cells respond to far lower concentrations of E2 than previously recognized or examined, and this response is mediated through two distinct mechanisms, depending on its origin. This may provide the basis for new insights into the causes of, and possible treatments for, BPH.

Estradiol-mediated ERK phosphorylation and apoptosis in vascular smooth muscle cells requires GPR 30

Recent studies suggest that the rapid and nongenomic effects of estradiol may be mediated through the G protein-coupled receptor dubbed GPR30 receptor. The present study examines the role of GPR30 versus a classical estrogen receptor (ERalpha) in mediating the growth regulatory effects of estradiol. GPR30 is readily detectable in freshly isolated vascular tissue but barely detectable in cultured vascular smooth muscle cells (VSMC). In freshly isolated aortic tissue, estradiol stimulated extracellular signal-regulated kinases (ERK) phosphorylation. In contrast, in cultured VSMC, where GPR30 expression is significantly reduced, estradiol inhibits ERK phosphorylation. Transfer of the genes encoding GPR30 led to estradiol stimulation of ERK phosphorylation, which is opposite the effects of estradiol in the primary culture of VSMCs. Transduction of the mineralocorticoid receptor (MR) had no effect on estradiol effects on ERK. Estradiol-mediated stimulation of ERK subsequent to heterologous GPR30 expression was pertussis toxin sensitive and phosphoinositide 3-kinase (PI3 kinase) dependent; under these conditions, estradiol also inhibited protein kinase A (PKA). In contrast, in the absence of GPR30 expression in cultured VSMC, estradiol stimulated PKA activity and inhibited ERK phosphorylation. To determine the functional effect of GPR30 (vs. estrogen receptor expression), we assessed estradiol-mediated apoptosis. In the absence of GPR30 expression, estradiol inhibited apoptosis. This effect was enhanced with ERalpha expression. In contrast, with GPR30 expression, estradiol stimulated apoptosis in an ERK-dependent manner. Thus the effect of estradiol on vascular smooth muscle cell apoptosis is likely dependent on the balance between ER-mediated PKA activation and GPR30-mediated PKA inhibition and PI3 kinase activation. Taken together, we postulate that modulation of GPR30 expression or activity may be an important determinant of the effects of estradiol in the vasculature.

Proliferation and phenotypic changes of stromal cells in response to varying estrogen/androgen levels in castrated rats

It is known that human benign prostatic hyperplasia might arise from an estrogen/androgen (E/T) imbalance. We studied the response of castrated rat prostate to different ratios of circulating E/T. The castrated male Wistar rats were randomly injected with E/T at different ratios for 4 weeks. The prostates of E/T (1:100) group showed a distinct prostatic hyperplasia response by prostatic index, hematoxylin and eosin staining, and quantitative immunohistochemical analysis of alpha-smooth muscle actin (SMA). In this group, cells positive for Vimentin, non-muscle myosin heavy chain (NMMHC) and proliferating cell nuclear antigen (PCNA) increased in the stroma and epithelium. Furthermore, the mRNA levels of smooth muscle myosin heavy chain (SMMHC) and NMMHC increased. So E/T at a ratio of 1:100 can induce a stromal hyperplastic response in the prostate of castrated rats. The main change observed was an increase of smooth muscle cells, whereas some epithelial changes were also seen in the rat prostates.

Autocrine human growth hormone expression leads to resistance of MCF-7 cells to tamoxifen

Tamoxifen is the most common antiestrogen used in the treatment of estrogen-positive breast cancer but its adverse effects and also resistance to this drug are serious challenges in the treatment of breast cancer. Characterization of mechanisms responsible for these adverse effects can lead to design of more efficient therapeutic strategies for the treatment of breast cancer. Here, we used a cellular model to evaluate the effects of autocrine expression of human growth hormone on responses of cells to tamoxifen. Our results imply for the first time that autocrine expression of growth hormone in human breast adenocarcinoma cell line, MCF-7, results in increase in cell proliferative capacity of cells even in the presence of tamoxifen. This effect may be due to up-regulation of G-coupled estrogen receptor, GPR30, which is activated by tamoxifen.

Effect of selective estrogen receptor modulators on cell proliferation and estrogen receptor activities in normal human prostate stromal and epithelial cells

We examined the effect of E(2) and selective estrogen receptor modulators (SERMs) on the proliferation and estrogen receptor (ER) activities in normal human prostate cells. SERMs such as toremifene, raloxifene and tamoxifen suppressed the proliferation of prostate epithelial and stromal cells whereas anti-androgens did not. In prostate stromal cells, the transactivation activities of ER were enhanced by adding E(2) and reduced remarkably by toremifene. The results indicate that the ER-mediated pathway plays a central role in the growth of normal prostate cells.

Role of HIF-1alpha and VEGF in human mesenchymal stem cell proliferation by 17beta-estradiol: involvement of PKC, PI3K/Akt, and MAPKs

17beta-Estradiol (E(2)) is a steroid hormone well known for its roles in the regulation of various cell functions. However, the precise role that E(2) plays in the proliferation of human mesenchymal stem cells (hMSCs) has not been completely elucidated. In the present study, we examined the effects of E(2) on cell proliferation and the related signaling pathways using hMSCs. We showed that E(2), at > or =10(-9) M, significantly increased [3H]thymidine incorporation after 24 h of incubation, and E(2) also increased [3H]thymidine incorporation at >6 h. Also, E(2) significantly increased the percentage of the cell population in the S phase based on FACS analysis. Moreover, E(2) increased estrogen receptor (ER), PKC, phosphatidylinositol 3-kinase (PI3K)/Akt, and MAPK phosphorylation. Subsequently, these signaling molecules were involved in an E(2)-induced increase of [3H]thymidine incorporation. E(2) also increased hypoxia-inducible factor (HIF)-1alpha and VEGF protein levels. These levels of protein expression were inhibited by ICI-182,780 (10(-6) M, an ER antagonist), staurosporine and bisindolylmaleimide I (10(-6) M, a PKC inhibitor), LY-294002 (10(-6) M, a PI3K inhibitor), Akt inhibitor (10(-5) M), SP-600125 (10(-6) M, a SAPK/JNK inhibitor), and PD-98059 (10(-5) M, a p44/42 MAPKs inhibitor). In addition, HIF-1alpha small interfering (si)RNA and ICI-182,780 inhibited E(2)-induced VEGF expression and cell proliferation. VEGF siRNA also significantly inhibited E(2)-induced cell proliferation. In conclusion, E(2) partially stimulated hMSC proliferation via HIF-1alpha activation and VEGF expression through PKC, PI3K/Akt, and MAPK pathways.