Immunohistochemical evaluation of estrogen receptor status in benign prostatic hypertrophy and in prostate carcinoma and the relationship to efficacy of endocrine therapy

Nuclear Estrogen Receptors in Prostate Cancer: From Genes to Function

Estrogens are almost ubiquitous steroid hormones that are essential for development, metabolism, and reproduction. They exert both genomic and non-genomic action through two nuclear receptors (ERα and ERβ), which are transcription factors with disregulated functions and/or expression in pathological processes. In the 1990s, the discovery of an additional membrane estrogen G-protein-coupled receptor augmented the complexity of this picture. Increasing evidence elucidating the specific molecular mechanisms of action and opposing effects of ERα and Erβ was reported in the context of prostate cancer treatment, where these issues are increasingly investigated. Although new approaches improved the efficacy of clinical therapies thanks to the development of new molecules targeting specifically estrogen receptors and used in combination with immunotherapy, more efforts are needed to overcome the main drawbacks, and resistance events will be a challenge in the coming years. This review summarizes the state-of-the-art on ERα and ERβ mechanisms of action in prostate cancer and promising future therapies.

Estrogen and Androgen Blockade for Advanced Prostate Cancer in the Era of Precision Medicine

Androgen deprivation therapy (ADT) has been widely prescribed for patients with advanced prostate cancer (PC) to control key signaling pathways via androgen receptor (AR) and AR-collaborative transcriptional factors; however, PC gradually acquires a lethal phenotype and results in castration-resistant PC (CRPC) during ADT. Therefore, new therapeutic strategies are required in clinical practice. In addition, ARs; estrogen receptors (ERs; ERα and ERβ); and estrogen-related receptors (ERRs; ERRα, ERRβ, and ERRγ) have been reported to be involved in the development or regulation of PC. Recent investigations have revealed the role of associated molecules, such as KLF5, FOXO1, PDGFA, VEGF-A, WNT5A, TGFβ1, and micro-RNA 135a of PC, via ERs and ERRs. Selective ER modulators (SERMs) have been developed. Recently, estrogen and androgen blockade (EAB) using a combination of toremifene and ADT has been demonstrated to improve biochemical recurrence rate in treatment-naïve bone metastatic PC. In the future, the suitability of ADT alone or EAB for individuals may be evaluated by making clinical decisions on the basis of information obtained from RT-PCR, gene-panel, or liquid biopsy to create a “personalized medicine” or “precision medicine”. In this review, we summarize ER and ERR signaling pathways, molecular diagnosis, and SERMs as candidates for advanced PC treatment.

Importance of Estrogenic Signaling and Its Mediated Receptors in Prostate Cancer

Prostate cancer (PCa) treatment was first established by Huggins and Hodges in 1941, primarily described as androgen deprivation via interference of testicular androgen production. The disease remains incurable with relapse of hormone-refractory cancer after treatments. Epidemiological and clinical studies disclosed the importance of estrogens in PCa. Discovery of estrogen receptor ERβ prompted direct estrogenic actions, in conjunction with ERα, on PCa cells. Mechanistically, ERs upon ligand binding transactivate target genes at consensus genomic sites via interactions with various transcriptional co-regulators to mold estrogenic signaling. With animal models, Noble revealed estrogen dependencies of PCa, providing insight into potential uses of antiestrogens in the treatment. Subsequently, various clinical trials were conducted and molecular and functional consequences of antiestrogen treatment in PCa were delineated. Besides, estrogens can also trigger rapid non-genomic signaling responses initiated at the plasma membrane, at least partially via an orphan G-protein-coupled receptor GPR30. Activation of GPR30 significantly inhibited in vitro and in vivo PCa cell growth and the underlying mechanism was elucidated. Currently, molecular networks of estrogenic and antiestrogenic signaling via ERα, ERβ and GPR30 in PCa have not been fully deciphered. This crucial information could be beneficial to further developments of effective estrogen- and antiestrogen-based therapy for PCa patients.

DNA methylation in promoter region as biomarkers in prostate cancer

The prostate gland is the most common site of cancer and the second leading cause of cancer death in American men. Recent emerging molecular biological technologies help us to know that epigenetic alterations such as DNA methylation within the regulatory (promoter) regions of genes are associated with transcriptional silencing in cancer. Promoter hypermethylation of critical pathway genes could be potential biomarkers and therapeutic targets for prostate cancer. In this chapter, we updated current information on methylated genes associated with the development and progression of prostate cancer. Over 40 genes have been investigated for methylation in promoter region in prostate cancer. These methylated genes are involved in critical pathways, such as DNA repair, metabolism, and invasion/metastasis. The role of hypermethylated genes in regulation of critical pathways in prostate cancer is discussed. These findings may provide new information of the pathogenesis, the exciting potential to be predictive and to provide personalized treatment of prostate cancer. Indeed, some epigenetic alterations in prostate tumors are being translated into clinical practice for therapeutic use.

Promoter hypermethylation in prostate cancer

BACKGROUND

The prostate gland is the most common site of cancer and the second leading cause of cancer mortality in American men. It is well known that epigenetic alterations such as DNA methylation within the regulatory (promoter) regions of genes are associated with transcriptional silencing in cancer. Promoter hypermethylation of critical pathway genes could be potential biomarkers and therapeutic targets for prostate cancer.

METHODS

This review discusses current information on methylated genes associated with prostate cancer development and progression.

RESULTS

Over 30 genes have been investigated for promoter methylation in prostate cancer. These methylated genes are involved in critical pathways, such as DNA repair, metabolism, and invasion/metastasis. The role of hypermethylated genes in regulation of critical pathways in prostate cancer is reviewed.

CONCLUSIONS

These findings may provide new information of the pathogenesis of prostate cancer. Certain epigenetic alterations in prostate tumors are being translated into clinical practice for therapeutic use.

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.

Acquisition of androgen independence by human prostate epithelial cells during arsenic-induced malignant transformation

Lethal phenotypes of human prostate cancer are characterized by progression to androgen independence, although the mechanisms behind this progression remain unclear. Arsenic is a potential human prostate carcinogen that may affect tumor progression. In this study, we used a prostate cancer cell model in which an immortalized, nontumorigenic human prostate epithelial cell line (RWPE-1) had been malignantly transformed by chronic low-level arsenic to help determine whether arsenic affects prostate tumor progression. Control and CAsE-PE (chronic-arsenic-exposed human prostate epithelial) cells were continuously maintained in a complete medium [keratinocyte serum-free medium (K-SFM) with bovine pituitary extract and epidermal growth factor] or in a steroid-depleted medium (K-SFM alone). The arsenic-transformed cells showed a more rapid proliferation rate in complete medium than did control cells and also showed sustained proliferation in steroid-reduced medium. Although both control and CAsE-PE cells showed similar levels of androgen receptor (AR), androgens were less effective in stimulating cell proliferation and AR-related gene expression in CAsE-PE cells. For instance, dihydrotestosterone caused a 4.5-fold increase in prostate-specific antigen transcript in control cells but only a 1.5-fold increase in CAsE-PE cells. CAsE-PE cells also showed relatively low levels of growth stimulation by nonandrogen steroids, such as estradiol. Thus, arsenic-induced malignant transformation is associated with acquired androgen independence in human prostate cells. This acquired androgen independence was apparently not due to AR up-regulation, increased activity, or altered ligand specificity. The precise manner in which arsenic altered CAsE-PE growth and progression is undefined but may involve a bypass of AR involving direct stimulation of downstream signaling pathways.

A rat endometrial cell line (R1-49E1) expressing estrogen receptor-alpha regulated by the tet-off system

BACKGROUND

Estrogens exert profound effects on target tissues. These effects are mediated by two estrogen receptors (ER(alpha) and ER(beta)) that bind to specific DNA sequences in estrogen-dependent genes. Other molecules such as growth factors, transcription factors and some oncoproteins might interact with the estrogen receptors and thus regulate the transcription of these genes. Currently there is no adequate cellular model to study these interactions.

METHODS

We transfected the human wild-type ER(alpha) to an ER-negative rat epithelial endometrial cell line (Rentr01) using a tetracycline-regulated gene expression system. The exogenous receptor was correctly translated, had an appropriate hormone-binding affinity, and bound well to estrogen response elements containing DNA.

RESULTS

We obtained a new stable cell line that is ER(beta) negative but ER(alpha) positive (R1-49E1). The expression of receptor alpha can be regulated in a dose-response manner by addition of tetracycline in the culture medium. Estradiol treatment of ER(alpha)-containing cells apparently diminished cellular proliferation, and the exogenous receptor can induce the transcription of the endogenous progesterone receptor isoform B (PgR-B) gene.

CONCLUSIONS

This epithelial cellular model may be useful to study the interaction between estrogens and other cell signaling pathways in epithelial endometrial cell physiology.

Epigenetic changes in prostate cancer: implication for diagnosis and treatment

Prostate cancer is the most common noncutaneous malignancy and the second leading cause of cancer death among men in the United States. DNA methylation and histone modifications are important epigenetic mechanisms of gene regulation and play essential roles both independently and cooperatively in tumor initiation and progression. Aberrant epigenetic events such as DNA hypo- and hypermethylation and altered histone acetylation have both been observed in prostate cancer, in which they affect a large number of genes. Although the list of aberrantly epigenetically regulated genes continues to grow, only a few genes have, so far, given promising results as potential tumor biomarkers for early diagnosis and risk assessment of prostate cancer. Thus, large-scale screening of aberrant epigenetic events such as DNA hypermethylation is needed to identify prostate cancer-specific epigenetic fingerprints. The reversibility of epigenetic aberrations has made them attractive targets for cancer treatment with modulators that demethylate DNA and inhibit histone deacetylases, leading to reactivation of silenced genes. More studies into the mechanism and consequence of demethylation are required before the cancer epigenome can be safely manipulated with therapeutics as a treatment modality. In this review, we examine the current literature on epigenetic changes in prostate cancer and discuss the clinical potential of cancer epigenetics for the diagnosis and treatment of this disease.

DNA methylation in prostate cancer

Prostate cancer is the most common malignancy and the second leading cause of cancer death among men in the United States. There are three well-established risk factors for prostate cancer: age, race and family history. The molecular bases for these risk factors are unclear; however, they may be influenced by epigenetic events. Epigenetic events covalently modify chromatin and alter gene expression. Methylation of cytosine residues within CpG islands on gene promoters is a primary epigenetic event that acts to suppress gene expression. In tumorigenesis, the normal functioning of the epigenetic-regulatory system is disrupted leading to inappropriate CpG island hypermethylation and aberrant expression of a battery of genes involved in critical cellular processes. Cancer-dependent epigenetic regulation of genes involved in DNA damage repair, hormone response, cell cycle control and tumor-cell adhesion/metastasis can contribute significantly to tumor initiation, progression and metastasis and, thereby, increase prostate cancer susceptibility and risk. In this review, we will discuss current research on genes that are hypermethylated in human prostate cancer. We will also discuss the potential involvement of DNA methylation in age-related, race-related and hereditary prostate cancer, and the potential use of hypermethylated genes as biomarkers to detect prostate cancer and assess its risk.

Age-dependent methylation of ESR1 gene in prostate cancer

The incidence of prostate cancer increases dramatically with age and the mechanism underlying this association is unclear. Age-dependent methylation of estrogen receptor alpha (ESR1) gene has been previously implicated in other cancerous and benign diseases. We evaluated the age-dependent methylation of ESR1 in prostate cancer. The methylation status of ESR1 in 83 prostate cancer samples from patients aged 49 to 77 years (mean age at 67.4 years) was examined using the bisulfite genomic sequencing technique. The samples were divided into three age groups: men aged 60 years and under (n = 14), men aged 61-70 years (n = 40), and men aged over 70 years (n = 29). Overall, ESR1 promoter methylation was detected in 54 out of 83 (65.1%) prostate samples. The methylation rate of ESR1 increased dramatically with age from 50.0% in patients aged 60 years and under to 89.7% for patients aged 70 years and over. Logistic regression analyses revealed that age and Gleason score were the only variables that affect incidence of ESR1 methylation; other clinical factors such as prostate-specific antigen level and clinical stage did not. We also calculated ESR1 methylation density (the percentage of methylated CpGs among all CpGs within the analyzed region) and severity (the percentage of methylated CpG alleles) for each sample analyzed. Multiple regression analyses showed a positive correlation between age and methylation density (beta, 0.35; P, 0.012; 95% CI, 0.26-2.01); while Gleason score was positively associated with methylation severity (beta, 0.45; P, 0.018; 95% CI, 1.04-4.26). These findings suggest that methylation of ESR1 is both age-dependent and tumor differentiation-dependent and age-dependent methylation of ESR1 may represent a mechanism linking aging and prostate cancer.

Regulation of estrogen receptor alpha and beta expression by testosterone in the rat prostate gland

Although ER beta is known to be expressed at high levels in the rat prostate gland, its regulation is not well understood. Here we examined ER mRNA expression and the effects of testosterone administration in male rats at 1, 4 and 9 weeks of age who were castrated and/or treated with testosterone for a week, and then sacrificed. ER alpha was the major type of ER expressed in 2 week-old animals while dominant expression of ER beta mRNA was apparent in older age groups. Interestingly while ER beta expression was diminished and ER alpha mRNA increased in the castrated group, testosterone administration reversed this effect. A time-course study indicated that induction of ER beta mRNA increased within 9 hr and ER alpha decreased in 2 days after an injection (i.p.) of testosterone. Our results suggested that 1) testosterone up-regulates ER beta mRNA expression while ER alpha is down-regulated; and that 2) great changes in ER alpha and beta expression in the prostate gland during development from the newborn to adult may be due to the influence of testosterone.

Hypermethylation can selectively silence multiple promoters of steroid receptors in cancers

Multiple promoters and differential splicing of 5' upstream exons are often found in various nuclear receptor genes including steroid receptors. Three promoters control the expression of human estrogen receptor alpha (ERalpha) isoforms: ERalpha-A, ERalpha-B, and ERalpha-C, and two promoters control the expression of human progesterone receptor (PR) isoforms: PR-A and PR-B. The expression levels of these isoforms differ with respect to each other in certain target tissues. The role of these isoforms may differ in various types of cells and tissues. The ER and PR contain CpG islands in the 5' upstream regions. One possible mechanism for changing the transcriptional status is methylation of CpG-enriched regions in these isoforms. We have investigated the expression and methylation status of the three different ERalpha promoters and the two different PR gene promoters by using methylation specific PCR (MSP) and direct DNA sequencing in several endometrial and prostate cancer cell lines and tissues. The results of these experiments suggest that ERalpha-A, ERalpha-B, and PR-A were expressed and ERalpha-C and PR-B were inactivated in endometrial cancers. To the contrary, ERalpha-A and ERalpha-B were inactivated and ERalpha-C, PR-A and PR-B were expressed in all prostate cancer. Treatment with demethylating agent (5-aza-2'-deoxycytidine) restored these gene expressions, suggesting that inactivation of this gene is through methylation. Our MSP and direct DNA sequencing showed that ERalpha-A, ERalpha-B, and PR-A genes were unmethylated and ERalpha-C and PR-B were methylated in endometrial cancers although ERalpha-A and ERalpha-B were methylated and ERalpha-C, PRA and PRB were unmethylated in prostate cancers. These reports clearly demonstrate that selective hypermethylation can selectively silence multiple promoters of steroid receptors in carcinogenesis.

CGA gene (coding for the alpha subunit of glycoprotein hormones) overexpression in ER alpha-positive prostate tumors

OBJECTIVE

The precise role of estrogen, estrogen receptor (ER) and ER-responsive genes in prostate carcinogenesis is unclear. Paradoxically, estrogens and antiestrogens are used in the treatment of advanced metastatic prostate cancers. Recently, we identified CGA gene coding for the alpha subunit of glycoprotein hormones as a new ER alpha-responsive gene in human breast cancer cells. The aim of this study was to explore the role of CGA in the second major hormone-related cancer, i.e. prostate cancer.

PATIENTS AND METHODS

We quantified CGA mRNA in nine cases of benign prostatic hyperplasia (BPH) and 23 sporadic prostate tumors (TP) by using a real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay.

RESULTS

CGA overexpression (> 10 S.D. above the mean in normal prostate tissues (NP)) was observed in 39% of the TP (ranging from 4.4 to 174.5 times the level in NP) and in none of the BPH samples. CGA overexpression was not accompanied by overexpression of the CGB, LHB, TSHB or FSHB genes to produce ectopic glycoprotein hormones. CGA gene overexpression correlated with ER alpha normal expression (P = 0.016), but not with ER beta or androgen receptor (AR) expression status.

CONCLUSION

These results point to CGA gene as a member of a novel dysregulated pathway in prostate cancer. CGA should therefore be considered for investigation as possible novel molecular marker in clinical applications and as possible new potential therapeutic target.

DNA methylation of nuclear receptor genes--possible role in malignancy

The members of the nuclear receptor superfamily are known to mediate a wide array of basic biological processes, such as regulation of cell growth and differentiation, and induction of apoptosis. In several human malignancies, this central control function of nuclear receptors is disturbed, which seems to play an important role in tumor development and progression. Many nuclear receptor genes have been reported to be downregulated in malignancies; however, only a few mutations, gene arrangements, deletions or similar genetic changes have been shown to occur in these tumors. During the last decade, increasing attention has been directed towards epigenetic mechanisms of gene regulation such as DNA methylation. Many nuclear receptor genes can be silenced through aberrant methylation in tumors; epigenetic silencing, therefore, represents an additional mechanism that modifies expression of key genes during carcinogenesis. This review will give insights into the role of DNA methylation in the silencing of nuclear receptor genes and its involvement in human malignancies.

Differential expression of estrogen receptor beta (ERbeta) and its C-terminal truncated splice variant ERbetacx as prognostic predictors in human prostatic cancer

Estrogens have been widely used for the treatment of advanced prostatic adenocarcinoma. However, their direct effect to prostatic cancer cells via estrogen receptors remains unclear. We investigated expression of ERalpha, wild-type ERbeta (wtERbeta), and a C-terminal truncated splice variant of ERbeta (ERbetacx) in 50 benign and 100 malignant human prostatic tissue samples by immunohistochemistry. While strong immunostaining of ERalpha was consistently identified in the stromal compartment, wtERbeta was expressed in epithelial cells in both the benign and malignant foci. However, wtERbeta expression was significantly lower in the cancers than in the benign epithelium and inversely correlated with Gleason tumor grade (P < 0.0001 and P = 0.0099, respectively). In contrast, ERbetacx was significantly more expressed in the high-grade cancers (83%) compared with the low-grade tumors (22%) and the benign sites (11%) (P < 0.0001, both). Cancer-specific survival of patients with lower wtERbeta expression was significantly worse than those with higher expression of wtERbeta (P = 0.0018). Conversely, higher ERbetacx expression significantly correlated with poor cancer-specific survival (P = 0.0058). These results suggest that differential expressions of wtERbeta and ERbetacx may be prognostic predictors for prostatic cancer.

Inhibition of growth and cell cycle arrest of ARCaP human prostate cancer cells by ectopic expression of ER-alpha

The estrogen receptor-alpha (ER-alpha) is a ligand-dependent transcription factor that regulates the growth, differentiation, and development of hormone-responsive target organs. While ER-alpha has been reported to play critical role in the pathogenesis and prognosis of breast and prostate cancers, its possible functional role in regulating prostate cancer cell growth in a ligand-dependent or -independent manner is poorly understood. We addressed this question by stably transfecting wild type (wt) ER-alpha cDNA into an invasive estrogen receptor-negative human prostate cancer cell line ARCaP. We isolated several clonal lines of transfected cells expressing varying levels of ER-alpha. The ectopic expression of wt ER-a markedly inhibited the growth of ARCaP cells in vitro in an ER-a dose-dependent but ligand-independent manner. Flow cytometric analysis of the wt ER-alpha-transfected ARCaP cells revealed that wt ER-alpha expression arrested cell growth in G1 phase. Our results suggest that ER-alpha may regulate prostate cell growth and participate in the pathogenesis of prostate cancer. ER-alpha may be delivered and expressed ectopically to target prostate cancer progression.

Estrogen receptors in the human male prostatic urethra and prostate in prostatic cancer and benign prostatic hyperplasia

Estrogen receptors (ERs) in the prostate and prostatic urethra were examined in 33 men with benign prostatic hyperplasia (BPH) and in 11 with prostate cancer (PC). The Abbot monoclonal ER-ICA assay was used for immunohistochemical investigation. In the BPH group, ERs were revealed in the prostatic stroma in eight cases and in the glandular epithelium in one. In four cases ERs were seen in the prostatic stroma and in the glandular epithelium. In the prostatic urethra, ERs were found in 19 cases located in the urothelium, lamina propria and/or periurethral glands. In the PC group, ERs were demonstrated in the prostatic stroma and/or prostatic urethra in 6 out of 11 cases. In both BPH and PC patients, immunoreactivity was weak and confined to few cells, indicating low ER content in the prostate as well as in the prostatic urethra. Dextran-coated charcoal (DCC) analysis was used for detection and quanticization of cytosolic and nuclear ERs. In the BPH group, ERs were detected once in the prostate and prostatic urethra in the nuclear and cytosol, and additionally in the prostatic urethra in the cytosol fraction in three cases. In all cases, ER content was low, ranging from 10-15 fmol/mg protein. In the PC group, ERs were detected in the prostatic urethra and/or prostate in the cytosol fraction from two patients. The contents were low, ranging from 10-13 fmol/mg protein. We conclude that in human BPH and PC, ERs can be present in the prostate and prostatic urethra. In the prostate, ERs are mainly located in the stroma, but in BPH specimens they can also be found in the glandular epithelium. Biochemically, the use of the DCC analysis is of limited value, since ER content in the human prostate and prostatic urethra is at the limit of detection with this method.

Expression of pepsinogen II with androgen and estrogen receptors in human prostate carcinoma

The expression of pepsinogen II (PG II), an aspartyl proteinase usually involved in the digestion of proteins in the stomach, was immunohistochemically investigated in conjunction with androgen (AR) and estrogen receptor (ER) status in prostate adenocarcinomas. Of a total of 38 samples obtained from radical prostatectomies, 23 tumors (60.5%) were positive for PG II and there was a significant positive correlation to the expression of AR but not to ER. Cells positive for PG II were localized mainly to the peripheral zones of tumorous glands which, in normal prostate, are negative, and in areas also expressing AR. In addition, a significant correlation between AR and ER was detected in the prostate carcinomas examined, which suggests a hormone-dependent status. On the basis of these results, PG II expression might be closely related to hormonal alterations associated with the development of prostate tumors.

Localization of 1,25-dihydroxyvitamin D3 receptor (VDR) expression in human prostate

1,25-dihydroxyvitamin D3 (1,25(OH)2D3) has been found to have a variety of physiological functions, including effects on growth and differentiation in normal and malignant cells. The antiproliferative effects of 1,25(OH)2D3 are reported to be mediated through the genomic signaling pathway by binding to a specific high affinity receptor protein, the 1,25-dihydroxyvitamin D3 receptor (VDR). VDR has been localized in a variety of tissues, but little is known about VDR distribution in human prostate. In this study, we raised an antibody against a synthetic peptide corresponding to amino acids 10-24 of human vitamin D receptor. The sequence selected for immunization is identical in human, rat and mouse VDR. Based on this antibody, we developed an immunohistochemical method suitable for studying VDR expression in paraffin-embedded tissue. The immunohistochemical staining was verified using classical target organs for vitamin D (kidney, intestine, skin). With this method, we studied VDR localization on paraffin-embedded human prostatic tissue obtained from 8 patients undergoing radical prostatectomy for urinary bladder cancer and demonstrate VDR expression in the secretory epithelial and few stromal cells of human prostate. The nuclear staining in the secretory epithelial cells was concentrated near the nuclear membrane and in discrete foci in the nucleoplasm. This suggests that effects of 1,25-dihydroxyvitamin D3 are mediated through VDR in these cells. Moreover our result indicates that there are strong variations in VDR expression between prostatic samples.

Androgen, estrogen, and progesterone receptors in normal and aging prostates

Testicular hormones regulate the growth and development of the prostate. The presence of androgen receptors in prostatic tissue and their importance in the normal development of the prostate has been established. Age-related changes in the hormonal milieu, and perhaps steroid hormone receptor profile, could set in motion pathological changes leading to the onset of benign prostatic hyperplasia (BPH) or prostate cancer which primarily affect older men. The accumulation of dihydrotestosterone with age, the reawakening of the inductive potential of the prostatic stroma, the altered rate of apoptosis with age, and the age-related changes in the ratio of testosterone:estrogen have all been implicated in the etiology of BPH. In addition to androgen receptors, several studies have documented the presence of estrogen and progesterone receptors in BPH and prostate cancer. So far, most studies have focussed on the correlation between the presence/absence of steroid hormone receptors and response to hormonal therapy. The molecular mechanisms by which these steroid hormone receptors regulate the onset or progression of BPH and prostate cancer are not yet clear. The chronological changes in the levels and distribution of steroid hormone receptors in normal prostatic tissue and the effect of such changes on the synthesis of growth factors, growth factor receptors, and oncogenes should be investigated.

Progressive activity in latent prostate carcinoma defined by argyrophilic staining of the nucleolar organizer regions (AgNOR)

Argyrophilic staining of the nucleolar organizer regions (AgNOR) was studied in 30 cases of benign prostatic hyperplasias (BPH), 17 cases of latent prostate carcinomas, 50 cases of clinical carcinomas and seven cases of metastatic lesions from prostate carcinomas. The criteria for these comparisons were the number of positive-staining dots per nucleus, the area of the dots, and a relative score determined by multiplying the number of positive-staining dots in the nuclei by the areas of the dots. Overall, there were no significant differences in these three parameters between BPH and latent carcinomas. Among latent carcinomas, however, significantly higher AgNOR scores were observed for infiltrative lesions than for non-infiltrative lesions. AgNOR dot number, area and score increased as tumors became less differentiated, with no significant differences detected in metastatic versus non-metastatic carcinomas. These results suggest that some latent tumors are similar in biological behavior, such as cell proliferation, to clinical carcinoma.