Benign prostatic hyperplasia--video image analysis and its relationship to androgen and epidermal growth factor receptor expression

Intrinsic and extrinsic factors causing hyperplasia of the prostate

Prostatic hyperplasia is very common in elderly men and is a typical disease that reduces quality of life. Histologically, hyperplasia of the prostate gland causes obstruction at the bladder outlet, resulting in symptoms such as a weak urine stream. Various factors have been considered to cause histological enlargement of the prostate, but the underlying cause is still unknown. The factors that cause prostate hyperplasia can be broadly classified into intrinsic and extrinsic ones. Extrinsic factors include things that we directly come into contact with such as bacteria and food. On the other hand, intrinsic factors are those that cause changes in functions originally provided in the body due to some cause, including extrinsic factors, such as chronic inflammation and an imbalance of sex hormones. A large number of reports have been made to date regarding the etiology of prostatic hyperplasia, although they have not yet clarified the fundamental cause(s). The various factors currently known should be outlined for future research. Should it be possible to prevent this highly prevalent prostatic hyperplasia which is mainly cause of dcreasing quality of life, there is no doubt that it would be a huge contribution to humanity.

Action, localization and structure-function relationship of growth factors and their receptors in the prostate

Whereas the direct action of sex steroids, namely of androgens, on prostate cell division was questioned as early as in the 1970s, and remains so, the interest in prostatic growth factors (GFs) is rather recent but has expanded tremendously in the last five years. This lag period can be partly explained by the fact that, at the time, androgen receptors had just been discovered, and newly developed hormonal regimens or strategies to treat patients with prostate carcinoma (PCa) or epithelioma had generated great enthusiasm and hopes in the medical and scientific community. Another point to consider was the difficulty in maintaining prostate tissues in organ cultures and the relative novelty of culturing prostate epithelial cells in monolayers. Failures of sex steroids to elicit a direct positive response on prostate cell divisionin vitro, as seenin vivo, were interpreted as resulting from inappropriate models or culture conditions. However, the increasing number of reports confirming the lack of mitogenic activity of sex steroidsin vitro, coupled with the powerful mitogenic activity of GFs displayed in other systems, the discovery of GF receptors (GF-Rs), and the elucidation of their signalling pathways showing sex steroid receptors as potential substrates of GF-activated protein kinases gradually led to an increased interest in the putative role of GFs in prostate physiopathology. Of utmost importance was the recognition that hormone refractiveness was responsible for PCa progression, and for the poor outcome of patients with advanced disease under endocrine therapies. This problem remains a major issue and it raises several key questions that need to be solved at the fundamental and clinical levels.

Bladder drainage and glandular epithelial morphometry of the prostate in benign prostatic hyperplasia with severe symptoms

OBJECTIVE

Morphometrically analyze the cells nuclei of the basal layer of the prostatic glandular epithelium in 20 patients aged between 57 and 85 years presenting benign prostatic hyperplasia with severe symptoms, catheterized or not.

MATERIALS AND METHODS

Patients with score of severe prostatic symptoms (with indication for transurethral resection of the prostate) were distributed according to the presence or absence of bladder drainage previous to the surgery, in the treated group (n = 10, catheter during 3 months) and in the control group (n = 10, without catheter). After obtaining prostate fragments through transurethral resection and the use of morphometric techniques, 100 nuclei of prostatic glands epithelium cells were studied (as to size and form), and compared to 500 nuclei from patients submitted to catheter drainage and 500 nuclei of non-catheterized patients.

RESULTS

Significantly reduced values of the major, medium and minor nuclear diameters, volume, area and perimeter, contour index and nuclear volume-nuclear area ratio were observed in the treated group in relation to the control group. As to the form, eccentricity and coefficient of nuclear form, there were significant differences between treated and control groups.

CONCLUSION

Long-term catheter bladder drainage in patients presenting benign prostatic hyperplasia with severe symptoms is associated to the reduction of morphometric parameters of the nuclei of prostatic glands' epithelial cells, suggesting a likely decompressive duct effect.

Preclinical Pharmacology of a Nonsteroidal Ligand for Androgen Receptor-Mediated Imaging of Prostate Cancer

Proper management of prostate cancer patients is highly dependent on the spread of the disease. High expression levels of the androgen receptor (AR) in prostate tumor offer a target for identifying cancer metastasis. We investigated the use of nonsteroidal AR ligands for receptor-mediated imaging as a diagnostic tool for prostate cancer staging. Compound S-26 [S-3-(4-fluorophenoxy)-2-hydroxy-2-methyl-N-(4-cyano-3-iodophenyl)-propionamide]was identified from a series of iodinated ether-linked derivatives of bicalutamide due to its high-AR binding affinity of 3.3 nM (which is similar to testosterone and approximately 25% of the binding affinity of dihydrotestosterone) in an in vitro competitive binding assay using rat prostate cytosol. Furthermore, S-26 exhibited a greater binding affinity (K(i) = 4.4 nM) in a whole-cell binding assay using COS-7 cells transfected with human AR than testosterone (K(i) = 32.9 nM) and dihydrotestosterone (K(i) = 45.4 nM). We also confirmed that sex hormone-binding globulin (SHBG), a plasma protein that binds steroids with high affinity, does not bind with S-26. Cotransfection studies with the estrogen, progesterone, and glucocorticoid receptor indicated that S-26 does not cross-react with other members of the steroid hormone receptor family. The nonsteroidal structure, high-AR binding affinity, specificity, and lack of binding to SHBG indicate that S-26 exhibits favorable properties for further development as an imaging agent for prostate cancer.

Intake of selected micronutrients and the risk of surgically treated benign prostatic hyperplasia: a case-control study from Italy

OBJECTIVE

To analyze the relationship between surgically treated benign prostatic hyperplasia (BPH) and intake of selected micronutrients.

METHODS

A multicentric case-control study was conducted in Italy between 1991 and 2002. Cases were 1369 men with histologically confirmed, surgically treated BPH and controls were 1451 men younger than 75 yr, frequency matched by quinquennium of age and study center, admitted to the hospital for acute nonneoplastic diseases. Information was collected by trained interviewers using a structured validated food-frequency questionnaire. The odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by unconditional multiple logistic regression models.

RESULTS

The risk of BPH significantly decreased with increasing intake of carotene (OR=0.80 for an increment equal to the difference between the 80th and 20th percentile of intake), alpha-carotene (OR=0.83), beta-carotene (OR=0.82), and cis beta-carotene (OR=0.82) and tended to decrease with the intake of vitamin C (OR=0.89) and iron (OR=0.79). The OR tended to increase with the intake of sodium (OR=1.30) and zinc (OR=1.10). No systematic heterogeneity was observed across strata of age, education, and body mass index. No meaningful associations emerged for other antioxidants, such as folic acid, lycopene, lutein/zeaxanthin, vitamin E, vitamin D, nor for retinol.

CONCLUSIONS

Our results suggest a protective effect of carotene on the risk of BPH. The risk tended to decrease also with the intake of vitamin C and iron and tended to increase with the intake of sodium and zinc. Results also indicate that other antioxidants, including folic acid, lycopene, lutein/zeaxanthin, and vitamins D and E, and retinol were not related to the risk for this disease.

History of weight and obesity through life and risk of benign prostatic hyperplasia

OBJECTIVE

The relation of anthropometric measures, diabetes, hypertension and hyperlipidemia with benign prostatic hyperplasia (BPH) risk was investigated.

DESIGN

Hospital-based case-control study.

SUBJECTS

Cases were 1369 men with histologically confirmed BPH, and controls were 1451 men below 75 y, admitted to hospital for acute non-neoplastic diseases.

MEASUREMENTS

Using a structured questionnaire, trained interviewers collected information on self-reported height and weight, and measured waist and hip circumference of patients. The odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional multiple logistic regression models.

RESULTS

Compared to the corresponding lowest quartile, the OR for the highest one were 0.76 (95% CI 0.59-0.98) for body weight, 0.71 (95% CI 0.54-0.94) for waist-to-hip ratio and 0.87 (95% CI 0.70-1.09) for body mass index (BMI, kg/m(2)). Compared to a lowest lifelong BMI <20.7 kg/m(2), the OR was 1.56 (95% CI 1.25-1.95) for a lowest lifelong BMI > or =23.7 kg/m(2). The OR was 0.74 (95% CI 0.60-0.93) for a lifelong increase of BMI > or =6.1 kg/m(2), compared to <1.6 kg/m(2). No association emerged for history of diabetes, hypertension and hyperlipidemia.

CONCLUSIONS

Overweight was modestly, inversely related to BPH. The hypothesis of reduced testosterone levels in obese individuals may explain the different BPH risk and need to be tested.

Androgen-independent basal cell re-epithelialization, c-erbB-2 mRNA expression and androgen-dependent EGFr mRNA expression in benign prostatic hyperplasia explant cultures treated with finasteride

We have analyzed the effects of the 5alpha-reductase inhibitor, finasteride (MK906), on the mRNA expression of the epidermal growth factor receptor and c-erbB-2 genes, in benign prostatic hyperplasia explant cultures treated with testosterone and with testosterone plus finasteride. A decrease of the epithelial cell content and an androgen-independent basal cell re-epithelialization was observed during the first 10 days of culture, suggesting a role of basal cells as stem cells involved in androgen-independent epithelial regeneration. Using a semi-quantitative reverse transcription polymerase chain reaction technique, we observed a significant decrease in expression of the epidermal growth factor receptor in the cultures treated with finasteride whereas no effect of finasteride on c-erbB-2 transcription was detected, although the expression of both genes was increased by dihydrotestosterone.

Coregulatory effects of epidermal growth factor, dihydrotestosterone, and prolactin on benign human prostatic hyperplasia tissue culture proliferation

BACKGROUND

A variety of hormones have demonstrated effects on prostatic tissue growth dynamics. Our goal was to define the effect of dihydrotestosterone (DHT), epidermal growth factor (EGF), and prolactin (PRL) on prostate cellular proliferation.

METHODS

Thirty benign human prostatic hyperplasias (BPH) were maintained 48 hr as in vitro cultures. Culture media were supplemented with EGF, DHT, and PRL alone and in combinations. Proliferation was assessed by labeling with tritiated thymidine.

RESULTS

The proliferative response of individual BPH cultures was heterogeneous. DHT and EGF tended to have a greater proliferative effect than PRL, both in terms of the percent cultures responding and the magnitude of the response. PRL antagonized EGF-induced proliferative effects. EGF- and PRL-mediated effects correlated with each other, while DHT-mediated effects did not correlate with either those of PRL or EGF.

CONCLUSIONS

The proliferative response of individual BPH to DHT, EGF, and PRL, alone or in combination, is too variable to define a predictable response to their influence. Our methodology represents a technique with the capacity to define therapeutic potential for individual cases.

Regulation of prostatic growth and function by peptide growth factors

Polypeptide growth factors are positive and negative regulators of prostatic growth and function. Expression and biological effects of epidermal growth factor (EGF), transforming growth factors (TGFs) alpha and beta, fibroblast growth factors (FGFs), and insulin-like growth factors (IGFs) in the prostate have been extensively studied. EGF and TGF alpha, which share the same receptor, are strong mitogens for prostatic epithelial and stromal cells. Their paracrine mode of action in normal tissue and early-stage tumors is apparently altered towards an autocrine stimulation in hormone-independent tumors, which gain the ability to produce TGF alpha by themselves. TGF beta has a dual role in the regulation of prostatic growth. It inhibits growth of prostatic epithelial cells in culture and mediates programmed cell death after androgen withdrawal. However, advanced prostatic carcinomas become insensitive to the inhibitory effect of TGF beta. Several members of the FGF family have been identified in the prostate. They are mainly or exclusively expressed in the stromal cells, and stimulate the epithelial cells. In the rat Dunning tumor model, progression is accompanied by distinct changes in the expression of FGFs and their receptors. In the hyperplastic tissue, basic FGF (bFGF) is accumulated. This growth factor is also a potent angiogenic inducer, expression of which may determine the metastatic capability of a tumor. IGFs are paracrine growth stimulators in the normal and hyperplastic prostate. It is still under consideration whether prostatic cancer cells gain the ability to produce IGF-I by themselves and thus shift to an autocrine mode of IGF-I stimulation. Growth factors also interact with the androgen-signaling pathway. IGF-I in particular, other growth factors as well, can activate the androgen receptor.

Regional distribution of epidermal growth factor, testosterone and dihydrotestosterone in benign prostatic hyperplasia tissue

In benign prostatic hyperplasia (BPH), basic fibroblast growth factor (bFGF) is found to have a regional distribution, with concentrations in the periurethral zone (where the primitive fibrostromal nodule originates) higher than those of the peripheral subcapsular zone. The aim of the present investigation was to verify whether androgens and epidermal growth factor (EGF) are uniformly distributed from the periurethral to the peripheral zone or whether they show regional differences. Tissue samples, removed by transvesical resection from nine untreated BPH patients, sectioned in periurethral, subcapsular, and intermediate zones, were examined. In the periurethral zone, dihydrotestosterone (DHT), testosterone, and EGF, determined by radioimmunoassay (RIA) techniques after purification on Celite microcolumns and Sep-pak C18 cartridge, showed values significantly higher (mean +/- SD: 1121 +/- 482 pg, 250 +/- 129 pg, and 6.89 +/- 3.28 ng/mg DNA, respectively; P < 0.01) than those of the subcapsular zone (489 +/- 190 pg, 114 +/- 70 pg, and 3.40 +/- 1.90 ng/mg DNA, respectively). A positive linear correlation between EGF, testosterone, and DHT was also observed. The regional distribution of EGF, testosterone, and DHT was similar to that found for bFGF: the highest levels of these factors in the periurethral region allow us to hypothesize on their possible involvement in the rewakening of mesenchymal tissue, leading to the formation of the primitive fibrostromal nodule and then to BPH development.

Influence of dihydrotestosterone, epidermal growth factor, and basic fibroblast growth factor on the cell kinetics of the PC3, DU145, and LNCaP prostatic cancer cell lines: relationship with DNA ploidy level

The cell kinetics (percentage of cells in the S+G2 phases of the cell cycle) and the DNA ploidy levels (nuclear DNA content) were determined in 108 samples each of the PC3, DU145, and LNCaP prostate cancer models. This was carried out by means of the digital cell image analysis of Feulgen-stained nuclei. Two to three hundred cell nuclei were analyzed for each of the 324 samples under study. The three cell lines were submitted to experimental conditions including the addition of dihydrotestosterone (DHT), epidermal growth factor (EGF), and basic fibroblast growth factor (bFGF), either alone or in combination, to the culture media. The results show that under the present culture conditions, the PC3 cell line was DHT-, EGF- and bFGF-insensitive. In contrast to what is generally reported in the literature, the DU145 cell line was DHT- and EGF-sensitive under the present culture conditions, but bFGF-insensitive. The LNCaP cell line was DHT-sensitive, but EGF- and bFGF-insensitive. While mainly tetraploid, the three cell lines nevertheless exhibited a significant level of heterogeneity in their nuclear DNA content distributions. Indeed, the proportions of non-tetraploid (diploid, hyperdiploid, triploid, hypertriploid, hypertetraploid, polymorphic) DNA histograms were 14% in the PC3, 16% in the DU145, and 29% in the LNCaP cell lines. These results suggest that the DNA ploidy level would not influence the hormone sensitivity level in the cell lines since they had significantly distinct hormone sensitivity profiles while remaining mainly tetraploid.

Ageing and prostate: age-related changes in androgen receptors of epithelial cells from benign hypertrophic glands compared with cancer

Total and nuclear androgen receptors (AR) were studied from epithelial cells in internal and external prostatic zones in 51- to 86-year-old individuals with benign prostatic hyperplasia (BPH) (n = 68) and prostatic cancer (n = 9). We focussed on the role played by androgens on those processes, despite the fact that at these ages, its secretion has normally decreased. In BPH, the nuclear AR do not change, but total measured androgen receptors rise with age (r = 0.5, P < 0.01). Total or nuclear AR do not correlate with gland volume, despite its increase with age (r = 0.8, P < 0.05). In prostates less than 180 cc in volume, there is a significant correlation between size, serum total testosterone level (r = 0.53, P < 0.05) and prostatic specific antigen (PSA) (r = 0.63, P < 0.05). The amount of nuclear AR in cells from the external zone (infiltrated by cancer or healthy) is two times greater than in those from the internal region. Total receptor content of the external zone cells is also high, but the sample is too small to demonstrate an age dependence. The results suggest that ageing is accompanied by an accumulation of non-nuclear AR in the cytosol, that does not play a role in the development of BPH because the amount of nuclear receptors remains unaltered. The enrichment in nuclear receptors of the external zone cells, independently of the presence of cancer, points to a greater androgen dependence in these cells than in cells of the internal region.

Zonal biochemical and morphological characteristics in BPH

OBJECTIVE

To compare androgen, oestrogen, progesterone and epidermal growth factor receptor concentrations in the transition zone and peripheral zone of the prostate in benign prostatic hyperplasia (BPH), and to relate these findings to epithelial and stromal composition.

PATIENTS AND METHODS

Tissue from both the transition and peripheral zone of the prostate was obtained from 26 patients undergoing transurethral prostatectomy for benign prostatic obstruction and used for both receptor binding studies and morphometric analysis. Androgen receptor (AR), oestrogen receptor (ER), progesterone receptor (PR) and epidermal growth factor receptor (EGFR) concentrations were assayed by saturation binding with a competitive inhibitor. The epithelial, stromal and luminal composition of the tissue was determined using a Zeiss AxioHOME microscope workstation.

RESULTS

The epithelial content was significantly greater in the transition zone than in the peripheral zone. No overall zonal difference in AR concentration was detected; however, when values were expressed relative to the epithelial component, the AR content was significantly higher in the peripheral zone. Conversely, overall EGFR concentrations were significantly greater in the transition zone, although not when expressed per unit epithelium. Higher concentrations of oestrogen receptor were measured in the transition zone per unit stroma. No zonal difference in PR was detected. However, there was a significant correlation between AR and PR in the peripheral zone and between EGFR and AR in the transition zone.

CONCLUSION

These data demonstrate that receptor concentrations should be related to tissue composition. Concentrations of AR were higher in the peripheral zone epithelium than in transition zone epithelium, suggesting greater androgen dependence. This may be important in determining its greater propensity for malignancy. Although EGFR concentrations were greater in the transition zone, there was no zonal difference after correction for the amount of epithelium. Finally, higher concentrations of ER were detected in the transition zone stroma which may reflect important zonal differences in regulating growth and provides further evidence of a role for oestrogens in BPH.

In situ hybridization for epidermal growth factor receptor (EGFR) external domain transcripts in prostatic adenocarcinoma

We examined prostatic adenocarcinomas from 19 formalin fixed radical prostatectomy specimens for EGFR by in situ hybridization employing a 24 base synthetic biotin-labeled oligonucleotide probe complementary to the 5' end of EGFR mRNA. All slides were examined by light microscopy using a 25x objective. Each field was given three values: 1) Gleason grade (1-5), 2) Nuclear grade [small (< 5.0 mu), intermediate (5-10 mu), large (> 10 mu)], and 3) EGFR staining intensity score (0, absent; 1, weak; 2+, moderate to strong). A total 851 25x fields of prostatic adenocarcinoma were studied. All cancers demonstrated at least some degree of cytoplasmic EGFR message. The EGFR intensity score correlated best with tumor nuclear size. No correlation with Gleason grade was observed. Cytoplasmic staining was also identified in the basal cell layer of benign glands, high grade prostatic intraepithelial neoplasia, stromal nodules, transitional epithelium, periurethral glands, and ganglion cells. Competitive hybridization experiments using an unlabeled EGFR probe showed markedly diminished hybridization signal, while in situ hybridization with a biotin-labeled EGFR sense probe was negative. Immunohistochemistry on 13 of the tumors with 2 monoclonal antibodies against EGFR showed staining in only 1/13 and 10/13 tumors. EGFR expression appears to be most prominent in tumors of high nuclear grade. Further studies will be necessary to explore this growth factor as a prognostic variable in this tumor.

Application of low magnification image analysis cytometry to prostatic tissue

Determination of the volume percentage of epithelial tissue present in prostatic tissue samples obtained by transurethral resection presents difficulties for high magnification (0.2-0.5 microns per pixel) measurement techniques due to the random orientation of tissue fragments when sectioned and the necessity of having to select "representative" areas for measurement. A low magnification (110 microns per pixel) image analysis technique was used to overcome these difficulties by allowing measurement of the epithelial tissue component to be made from the entire area of tissue available for microscopic examination. This technique which utilizes standard hematoxylin and eosin preparations was applied to 89 consecutive cases of benign prostatic hyperplasia, with measurement times of four mins per slide being obtained. Replicate measurement of 20 of these samples showed an average absolute difference between replicates of +/- 5.1 percent epithelial tissue. This method thus offers a simple, fast and practical alternative to high magnification methods of estimating the volume percentage of epithelial tissue when the selection of "representative" areas for measurement is complicated by specimen heterogeneity or when large numbers of specimens must be examined.