Relationship between upregulated oestrogen receptors and expression of growth factors in cultured, human, prostatic stromal cells exposed to estradiol or dihydrotestosterone

Fingolimod interrupts the cross talk between estrogen metabolism and sphingolipid metabolism within prostate cancer cells

Sphingolipids are critical regulators of tumor microenvironments and play an important role in estrogen-dependent cancers. Estrogen and estrogen metabolites were found to be involved in prostate cancer. Fingolimod (FTY720) is a sphingokinase-1 (SphK1) inhibitor with anticancer properties against various tumor cell types. Herein, we investigated the interference of FTY720 with the cross talk between sphingolipid metabolism and estrogen metabolism within prostate cancer cells. FTY720 showed cytotoxic antiproliferative effects against androgen-dependent and -independent prostate cancer cells with IC₅₀ ranging from 3.0 ± 0.3 to 6.8 ± 1.7 μM. Exposure of prostate cancer cells to FTY720 resulted in a dramatic decrease in the concentration of estradiol, estrone, 4-hydroxyestradiol and 16α-hydroxyestrone compared to control cells. However, FTY720 significantly increased the concentration of 2-methoxyestrone and 2-methoxyestradiol within prostate cancer cells. This was mirrored by significant downregulating of the expression of estrogen and catechol estrogen-synthesizing enzymes (CYP19, CYP1A1 and CYP1B1) within prostate cancer cells. On the other hand, FTY720 significantly upregulated the expression of catechol estrogen-detoxifying enzyme (COMT). Additionally, FTY720 abolished estrogen-stimulated expression of ERα and basal expression of ERβ within prostate cancer cells. Furthermore, FTY720 suppressed the expression of the ER-downstream regulated genes, CXCR4 and cyclin D1. Reciprocally, it was found that estradiol and catechol estrogens significantly induced the expression of SphK1 while methoxylated catechol estrogen suppressed its expression within prostate cancer cells in a dose-dependent manner. Current research has highlighted the hazardous influence of the estrogenic component to prostate cancer. We found that fingolimod (FTY720) could modulate the estrogenic micromilieu and interrupt its cross talk with sphingolipid metabolism.

Upregulation of Oxytocin Receptor in the Hyperplastic Prostate

Background: The etiology of benign prostatic hyperplasia (BPH) is complex, both age and androgen are thought to be important. However, the failure of androgen blockade treatments suggests other paracrine/autocrine factors involved in BPH. Oxytocin was found to have a paracrine/autocrine role in prostate in recent years. The influence of BPH on prostatic oxytocin receptor (OTR) expression has never been studied. Material and methods: A testosterone-estradiol induced rat model of BPH was employed and human hyperplastic prostate specimens were harvested. Expressions of OTR, α₁-adrenoreceptor subtypes and nitric oxide synthase isoforms were determined via real-time RT-PCR. OTR was further analyzed with Western-Blotting and histological examination. Subsequently, rat epithelial cells, human stromal cells and epithelial cells were cultured in vitro and treated with gradient concentrations of OT from 1 to 5 days. Cell proliferation was tested by Cell Counting Kit-8 and Flow Cytometry. Results: The rat BPH model was validated with significant increased prostate weight. H-E stain revealed a different histopathology between human and rat BPH. Masson's trichrome staining demonstrated that smooth muscle (SM) cells, epithelium cells and collagen fibers were simultaneously augmented in this rat BPH model and human BPH samples. OTR mainly localized in epithelium in rat prostate whereas it mainly localized in stroma in human prostate. OTR gene was upregulated 3.3-fold in rat BPH and 3.0-fold in human BPH, along with increased expression of 2.0-fold α_1aARs and 3.0-fold eNOS for rat BPH and 5.0-fold α_1aARs for human BPH. The expression of OTR protein was upregulated 1.4-fold in rat BPH and 3.9-fold in human BPH, respectively. Increased concentrations of exogenous OT can accelerate proliferation of rat epithelial cells and human stromal cells but has no impact on human epithelial cells in vitro. Flow Cytometry showed oxytocin could significantly increase G₂/M period cell number. Conclusions: Our novel data demonstrates a significant and previously undocumented upregulation of OTR in both rat and human BPH. Moreover, exogenous OT accelerates proliferation of rat prostate epithelial cells and human prostate stromal cells. It is suggested OTR is involved in the development of BPH and OT regulatory system could be a potential new target for the BPH treatment.

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.

Serum sex steroid hormones and lower urinary tract symptoms in Third National Health and Nutrition Examination Survey (NHANES III)

OBJECTIVES

To evaluate the association of circulating sex steroid hormones and sex hormone binding globulin (SHBG) with lower urinary tract symptoms (LUTS).

METHODS

We included 260 men, 60 years old or older, who participated in Phase 1 (1988 to 1991) of the Third National Health and Nutrition Examination Survey and for whom surplus serum was available. We measured the serum concentrations of testosterone, androstanediol glucuronide (AAG), estradiol, and SHBG. Free testosterone was calculated from the circulating testosterone, SHBG, and albumin. The cases (n = 128) were men with two to four symptoms (nocturia, hesitancy, incomplete emptying, and weak stream), but who had never undergone noncancer prostate surgery. The controls (n = 132) were men who neither had symptoms nor had undergone noncancer prostate surgery. We adjusted for age, race/ethnicity, waist circumference, cigarette smoking, alcohol consumption, and physical activity in logistic regression models and used sampling weights.

RESULTS

The cases had statistically significantly greater AAG and estradiol concentrations than did the controls. After multivariate adjustment, the men in the top tertile of AAG (odds ratio 2.62, 95% confidence interval 1.12 to 6.14) had a greater risk of LUTS compared with men in the bottom two tertiles. Also, men with a greater estradiol concentration (odds ratio 1.78, 95% confidence interval 0.91 to 3.49) and a greater estradiol/SHBG molar ratio (odds ratio 2.41, 95% confidence interval 1.39 to 4.17) had a greater risk of LUTS than did men with lower concentrations. No consistent associations were seen for circulating testosterone, free testosterone, or SHBG.

CONCLUSIONS

In this cross-sectional study representative of older U.S. men, circulating AAG, a metabolite of dihydrotestosterone, and estradiol were associated with an increased risk of having LUTS.

Estrogen receptor beta (ERbeta) and inhibition of prostate cancer cell proliferation: studies on the possible mechanism of action in DU145 cells

Estrogen receptor beta (ERbeta) plays a protective role against uncontrolled cell proliferation. ERbeta is lost during prostate cancer (CaP) progression suggesting its direct involvement in contrasting tumor proliferation in this disease; however, the molecular mechanism at the basis of this effect has not been clearly defined yet. Possible molecular targets of ERbeta were assessed in DU145 cells, a CaP cell line expressing only ERbeta. Cells treated from 1 to 9 days with different doses of estradiol or diarylpropionitrile (DPN, an ERbeta-selective agonist) show a time-dependent decrease in cell proliferation. The reduced proliferation rate is accompanied by the stimulation of ERbeta expression and the increase of cyclin-dependent kinase inhibitor p21. We demonstrate that the endogenous ERbeta is one of the mediator of the antiproliferative action of estrogens enhancing the synthesis of molecules such as p21 that control cell cycle, an effect amplified by the autoregulation of ERbeta expression. Our observations suggest that CaP, when expressing a functional ERbeta, might be sensitive to the antiproliferative action of estrogens; therefore, ERbeta specific agonists might be valid candidates for new pharmacological approaches to this disease.

Estrogen induced functional hypertrophy and increased force generation of the female rabbit bladder

AIMS

Estrogen is essential for physiological maintenance of the female urogenital tract. It is believed that alterations in female sex hormones play a major role in the etiology and response to urinary tract dysfunctions. In animal studies, ovariectomy (Ovx) results in smooth muscle (SM) weakness and atrophy whereas estrogen supplementation reverses these effects. Our study seeks to establish the mechanisms by which estrogen augmentation results in increased contractility.

METHODS

Twenty New Zealand White female rabbits were separated into five groups of four each. Group 1 served as control, rabbits of groups 2-5 were ovariectomized, group 2 ovariectomized received no estradiol, groups 3-5 were given 17-beta estradiol (1 mg/kg/day) by subcutaneous slow release tablet implant for 1, 3, and 7 days, respectively, beginning 2 weeks after Ovx. At the end of the experimental period, each rabbit was anesthetized and the urinary bladder was removed for contractile, histological, and biochemical studies.

RESULTS

Ovx resulted in significantly decreased bladder contractile function, whereas bladders tested after estradiol administration showed increased contractility. Ovx resulted in a decrease in SM/collagen ratio, whereas estrogen resulted in an increase. The estrogen receptor (ER) density significantly increased following Ovx. After 1 day of estrogen treatment, the ER density decreased significantly below control levels, but rose progressively during the estrogen treatment.

CONCLUSION

The present study demonstrates that estrogen supplementation mediates a "functional hypertrophy," that is a hypertrophy characterized by increased contractile responses to all forms of stimulation, and an increased ratio of SM/collagen.

A potential novel marker for human prostate cancer: voltage-gated sodium channel expression in vivo

Functional expression of voltage-gated sodium channel alpha-subunits (VGSCalphas), specifically Nav1.7, is associated with strong metastatic potential in prostate cancer (CaP) in vitro. Furthermore, VGSC activity in vitro directly potentiates processes integral to metastasis. To investigate VGSCalpha expression in CaP in vivo, immunohistochemistry and real-time PCR were performed on human prostate biopsies (n>20). VGSCalpha immunostaining was evident in prostatic tissues and markedly stronger in CaP vs non-CaP patients. Importantly, RT-PCRs identified Nav1.7 as the VGSCalpha most strikingly upregulated (approximately 20-fold) in CaP, and the resultant receiver-operating characteristics curve demonstrated high diagnostic efficacy for the disease. It is concluded that VGSCalpha expression increases significantly in CaP in vivo and that Nav1.7 is a potential functional diagnostic marker.