Morphometric and stereological study of the glandular epithelium of the lateral prostate of the intact and castrated guinea pig

The glandular epithelium of the lateral prostate of the guinea pig was described within the framework of a morphometric model in terms of relative densities and absolute dimensions. A combination of direct measurement and point and intersection counting techniques was used. The quantitative data generated in the intact animals were compared with those of castrated controls. Castration was accompanied by a significant decrease in height of the glandular epithelium and in sizes of secretory and basal cells and their corresponding nuclei. On a per cell basis, significant decreases in total volume and surface area of granular endoplasmic reticulum were detected after castration. This was accompanied by a significant reduction in the total volume of Golgi cisternae. The total volume, surface area, and number of highly electron-dense and clear granules decreased significantly compared with the intact control animals. However, no significant changes in these parameters of low electron-dense granules were found. Significant reductions in the total volume and surface area of condensing granules, lysosomes, and mitochondria, but not their number, were detected. The average sizes of condensing granules, secretory granules, lysosomes, and mitochondria were decreased significantly after castration. The present study showed that the alterations in the secretory function of the secretory cells of the lateral prostate was reflected by the quantitative changes in granular endoplasmic reticulum, Golgi complexes, and secretory granules on a per cell basis. The data generated in the present study will serve as a baseline for further studies of the lateral prostate of the guinea pig.     

Pharmacologically induced ultrastructural and immunohistochemical changes in the prostate of the castrated dog

The effects of an aromatase inhibitor and of an antiandrogen on the ultrastructure and the expression of a secretory protein (acid phosphatase) and marker proteins for basal cells (keratin) and fibroblasts (vimentin) were studied in the prostate of castrated, androstenedione-treated dogs. Androstenedione treatment partially restored the normal appearance of the gland and also some secretory activity. In the central portion of the gland, basal cell hyperplasia developed instead of secretory activity after androstenedione treatment. Administration of the aromatase inhibitor reduced the number of secretory cells but did not completely suppress the latter. There was some proliferation of the connective tissue surrounding the atrophic acini. Combined treatment with aromatase inhibitor and antiandrogen resulted in a general atrophy of prostatic acini that was less intense relative to the changes observed after castration. Residual secretory activity, detected in specimens treated exclusively with aromatase inhibitor, were lacking after combined treatment. The influence of all regimens on the ultrastructure of smooth muscle cells was comparably discrete, whereas regional differences in the arrangement pattern of the epithelium and the fibromuscular stroma were impressive. The ultrastructural findings support previous results of a synergic inhibitory effect of aromatase inhibitor and antiandrogens on the canine prostate.     

Changes in hormone sensitivity in the ventral prostate of aging Sprague-Dawley rats

The adult rat ventral prostate, which has been used extensively as a model for hormone-dependent prostate cancer, is composed of hormone-dependent columnar secretory epithelial cells and a mixture of hormone-independent cuboidal epithelial cells, basal epithelial cells, and stromal cells. Androgen ablation causes the gland to regress due to the selective loss of the secretory luminal epithelial cells that undergo apoptosis. Most, if not all, of the studies examining the induction of apoptosis and the mechanism of regression have used young adult males at around 3 months of age. Prostate cancer, however, is a disease of older males, and we have therefore investigated whether age-related changes in hormone sensitivity and apoptosis occur in the ventral prostate of aged animals (12 months old) compared to young animals (3 months old). We have observed distinct differences in the morphology of the prostate between young and old rats prior to castration and a significant slowing in the rate of regression after castration in older animals. These changes are accompanied by changes in lipofuscin accumulation and levels of the antioxidant enzymes catalase and manganese (Mn) superoxide dismutase in the gland.     

Cell proliferation and apoptosis in prostate tumors and adjacent non-malignant prostate tissue in patients at different time-points after castration treatment

BACKGROUND: Androgen ablation is the standard treatment for advanced prostate cancer but the short-term cellular effects are largely unknown. METHODS: Sextant prostate biopsies were taken from 77 prostate cancer patients before and 1-10 days after castration treatment. Apoptosis, cell proliferation, and morphology were studied in malignant and non-malignant tissue, using stereological and immunohistochemical methods. RESULTS: Epithelial cell proliferation was significantly decreased both in non-malignant and malignant epithelium already 1 day after therapy. It remained low until day 7, but increased thereafter in the remaining non-malignant epithelial cells and in some tumors. Epithelial cell apoptosis was significantly increased during the first week and then returned to basal levels. The maximal apoptotic indexes, seven- and two-times the intact levels in the non-malignant and malignant glands, respectively, were found at days 3-4 or even earlier in the tumors. Signs of tumor shrinkage such as glandular collapse and decreased tumor cell size were observed from day 3 in most tumors. DISCUSSION: The present study shows that the magnitude and kinetics of the response to castration in the normal human prostate is very similar to the response previously described in rodents. We also demonstrate that most human prostate tumors rapidly respond to castration indicating the need for further evaluation of when and how to best monitor the effects of hormone ablation therapy in prostate cancer patients.     

Cell kinetics and differentiation after hormonal-induced prostatic hyperplasia in the dog

BACKGROUND: Our aim was to characterize the immunophenotypical changes in canine prostate epithelium after hormonal-induced benign prostatic hyperplasia (BPH). METHODS: Castrated dogs (aged 1-2 and 9-12 years) were treated with vehicle (group C), androstanediol (group A), or androstanediol plus estradiol (group AE). Surgical prostate biopsies were obtained before and after castration and after hormonal treatment. Tissue sections were stained using antibodies specific for basal cells (34betaE12), transiently proliferating (TP)/amplifying cells (RCK103), and luminal exocrine cells (RGE53). RESULTS: Castration resulted in a marked reduction in specific immunoreactivity associated with luminal secretory cells and basal cells in young dogs. In older dogs the number of basal cells remained constant. Hormonal treatment (AE) resulted in an increased number of cells with an immunophenotype that was associated with the TP/amplifying cell compartment and hyperplastic luminal epithelium. CONCLUSIONS: The relative increase in TP/amplifying cells in hormonally induced BPH in the dog is in line with a stem-cell-derived proliferation. Moreover, the finding of androgen-independent basal cells in the prostate of older dogs may contribute to the enhanced risk of development of BPH with increasing age.     

The proliferative function of basal cells in the normal and hyperplastic human prostate

To obtain more insight into the proliferative function of basal and secretory cell types in human prostate, we studied the immunoprofile of three well-characterized proliferation-associated antigens (Ki-67, PCNA, MIB 1) in normal and hyperplastic prostate tissue. Distinction between labeled basal and secretory cell types was made by simultaneous demonstration of the proliferation-associated antigens and basal cell-specific cytokeratins in identical sections. In normal and hyperplastic acini, approximately 70% of labeled cells were of the basal cell phenotype. These data clearly suggest that the proliferative compartment of the normal and hyperplastic epithelium is located in the basal cell layer. Compared to normal and hyperplastic conditions, severe proliferative abnormalities were detected in high-grade prostate intraepithelial neoplasias (PIN), as documented by the extension of the proliferative compartment up to the luminal border. Conversely, approximately 70% of proliferating cells detected in atypical hyperplasias that progressed in invasive carcinomas were localized in the remaining basal cell layer. These findings may indicate the proliferative role of basal cells in the epithelial renewal, and the development of hyperplastic and neoplastic disorders in the human prostate. © 1994 Wiley-Liss, Inc.     

Cell proliferation in dysplasia of the prostate: Analysis by PCNA immunostaining

Patterns of cell proliferation in the prostate were compared between benign epithelium and dysplasia. Proliferating cell nuclear antigen (PCNA) immunostaining was used to quantitate proliferation, and basal cells were tallied separately from secretory cells with the aid of keratin immunostaining. Using a novel technique, absolute cell densities (cells/mm) were determined and used to calculate growth fractions. In benign epithelium, 83% of PCNA⁺ cells were basal cells, while only 7% of PCNA⁺ cells in dysplasia were basal cells and there was a clear separation between groups. This dramatic shift of the proliferative compartment to the secretory cells in dysplasia was accompanied only by a moderate increase in overall secretory cell density and moderate reduction in basal cell density, but these ranges overlapped those of benign epithelium. The median PCNA⁺ secretory cell “growth fraction” was 0.12% in benign epithelium and 1.06% in dysplasia. The findings presented give further support to the concept that dysplasia represents an evolutionary stage in the malignant transformation of prostatic epithelium. The patterns of change in PCNA immunostaining may reflect certain aspects of the biologic nature of malignant transformation. © 1995 Wiley-Liss, Inc.     

Single case report of prostate adenocarcinoma in a dog castrated three months previously. Morphological, biochemical, and endocrine determinations

During the course of another investigation, three dogs had been castrated 3 months previously. Upon completion of the experiment, it was discovered that one dog presented a spontaneous prostatic adenocarcinoma of intraalveolar proliferative type at histology. Prostate weight of this dog before castration was estimated to be 22 g by tridimensional measurement at laparotomy and remained relatively constant (19 g) 3 months after castration. These results indicate that if regression had occurred in some cell populations (androgen-dependent) it was only partial and masked by growth of androgen-independent cells. Analysis of 12 individual steroids in peripheral blood and in prostatic tissue attested of a normal adrenal secretory activity. A series of 15 hydrolytic enzymes along with receptors for androgen, estrogen, and progesterone, were determined in prostatic tissue obtained at sacrifice. Enzymatic activities were those of typical epithelial cells, and most of them remained relatively high despite low levels of circulating testosterone. However, two markers of androgen action in dog prostate, acid phosphatase and arginine esterase, were significantly reduced. Receptor levels were similar to those of castrated animals. Thus, cancer cells had probably retained some androgen sensitivity.     

Effect of the addition of estrogen to medical castration on prostatic size, symptoms, histology and serum prostate specific antigen in 4 men with benign prostatic hypertrophy.

A total of 4 men with benign prostatic hypertrophy who underwent medical castration therapy with a long-acting gonadotropin-releasing hormone agonist (leuprolide) for more than 6 months elected to add an estrogen transdermal patch (0.05 mg. to the skin biweekly) to the leuprolide regimen. The average prostatic size (transrectal ultrasound), serum prostate specific antigen (PSA) levels and symptoms of prostatism were dramatically decreased with leuprolide alone. The addition of estrogen for 6 months did not result in any change in prostate size, symptoms or serum PSA levels over that seen with leuprolide alone. The development of squamous metaplasia was noted in 1 man with leuprolide alone and in 1 man after the addition of estrogen. Immunohistochemical staining with anticytokeratin 903 antibodies reveals that squamous metaplasia appears to arise from prostatic basal cells. We postulate that the target cell for estrogen action in the prostate is the prostatic basal cell. In the absence of androgen the only direct effect of estrogens is the induction of squamous metaplasia.     

Interferon-gamma induces neuroendocrine-like differentiation of human prostate basal-epithelial cells

BACKGROUND: Prostatic neuroendocrine (NE) cells are intraglandular hybrid epithelial-neural-endocrine cells that express and secrete numerous hormones and neuropeptides, which presumably regulate growth, differentiation, and secretory activity of the prostatic epithelium. This specialized cell type appears to differentiate from a common basal/precursor/stem cell that also gives rise to the secretory epithelium. In order to elucidate mechanisms of NE-differentiation the effects of type 1 (alpha, beta) and type 2 (gamma) interferons (IFNs) on human prostate basal cells (PrECs) were evaluated. METHODS AND RESULTS: Application of alpha/beta IFN increased the expression of the cell-cycle inhibitor p21(CIP1) and inhibited DNA synthesis, while only IFN-gamma led to increased apoptosis, cell-cycle inhibitor p27(KIP1) upregulation, and differentiation of PrECs into NE-like cells. In vitro differentiated NE-like cells expressed the glycolytic enzyme neuron-specific enolase (NSE) and chromogranin A (CgA), known markers of NE-cells in vivo in the prostate. These NE-like cells also changed cytokeratin (CK) expression patterns by upregulating CK 8/18, predominantly found in terminally-differentiated secretory luminal/NE epithelial cells. CONCLUSIONS: IFN-gamma produced locally in the prostate by basal cells and, under proinflammatory conditions, by infiltrating lymphocytes could support NE cell differentiation and play a role in NE differentiation processes of tumor cells in hormone-refractory prostate cancer.     

Androgen and prostatic stroma

Aim: To investigate the effect of androgen on the proliferation, differentiation and regression of canine prostatic stromal cells in vivo and human stromal cells in vitro. Methods: Twenty-two dogs, including 15 normal prostate dogs and 7 prostatic hyperplasia dogs, had their serum concentration of testosterone and estrodiol determined by radioimmunoassay before and after castration. The expression of androgen receptor (AR) and estrogen receptor (ER) in the prostate were analysed by immunohistochemistry and semi-quantitative RT-PCR before and after castration. Light microscopy, transmission electron microscopy and TUNEL assay were carried out successively before and after castration to evaluate the prostatic histomorphology. In vitro serum-free cell cultures from human prostatic stroma were established and exposed to dihydrotestosterone (DHT). The proliferation of the cell culture was detected by MTT assay. The expression of TGFβ, bFGF, AR, and smooth muscle cell (SMC) specific proteins (myosin and/or sm     

Cell proliferation studies in rat prostate. I. The proliferative role of basal and secretory epithelial cells during normal growth

In the prostates of rats ranging from 10 days to 8 months of age, the proliferative activity of basal and secretory epithelial cells was studied. No clear evidence was found that basal cells alone represented the proliferative compartment, or that they were responsible for the replacement of secretory cells during normal turnover. Cell kinetic and morphological evidence indicated that basal and secretory cells were self-replicating cell types with discrete functions.     

Differentiation pathways and histogenetic aspects of normal and abnormal prostatic growth: A stem cell model

A stem cell model is presented for the organization of the prostatic epithelium that may explain normal and abnormal growth in the human prostate. This model is based on recent data indicating that: 1) The three basic cell types encountered in the prostatic epithelium—i.e., secretory luminal, basal, and endocrine paracrine (EP) cells—are linked in the precursor progeny relationship. 2) The proliferative compartment of the normal and hyperplastic epithelium is located in the basal cell layer. 3) The proliferative compartment of the prostatic epithelium is androgen-independent but contains androgen-responsive target cells. 4) During the malignant transformation of the prostatic epithelium, the proliferative zone is inverted and shifts to luminal cell types. 5) Formation of neoplastic basement membrane (BM) material is crucial for the development of the invasive phenotype in prostate cancer. 6) The proliferative activities in prostate cancer are exclusively restricted to exocrine cell types, whereas endocrine differentiated tumor cells are postmitotic cells. 7) The majority of exocrine tumor cells are androgen-responsive in contrast to endocrine differentiated cell types that consistently lack the nuclear androgen receptor (AR). In this model, a small stem cell population located in the basal cell layer gives rise to all epithelial cell lineages encountered in the normal, hyperplastic, and neoplastic prostate. The differentiating process from basal cells to secretory luminal cells via intermediate phenotypes is induced by circulating androgens, and largely depends on the presence of androgen-responsive target cells in the basal cell layer. Accordingly, the abnormal growth of the secretory epithelium in benign prostate hyperplasia (BPH) may be related to an increase in the total number of androgen-responsive basal cells in the proliferative compartment. Prostate cancer derives from transformed stem cells located in the basal cell layer that acquire secretory luminal characteristics under androgenic stimulation. During tumor invasion, the malignant phenotypes adhere via specific receptors to newly formed BM-material, which, in turn, may facilitate their passage through the extracellular matrix. The occurrence of endocrine differentiation in prostate cancer reflects the pluripotency of its stem cells. The widespread absence of nuclear AR in endocrine differentiated tumor cells clearly indicates that this phenotype belongs to those cell clones in prostate cancer, that are initially androgen-independent and refractory to hormonal therapy. Accordingly, the progressive emergence of endocrine cell clones during tumor progression may represent one mechanism by which prostate cancer cells escape hormonal control. © 1996 Wiley-Liss, Inc.     

Androgen ablation promotes neuroendocrine cell differentiation in dog and human prostate

BACKGROUND: Mechanisms triggering prostatic NE differentiation are poorly understood. Since dog and man naturally develop prostatic proliferative diseases with age, our objectives were to confirm the presence of NE cells in the dog prostate and test their hormonal regulation in both species. METHODS: Serotonin staining was examined by immunohistochemistry in 37 dog prostates: 17 from intact and 20 from castrated animals. In intact dogs, 9 prostates were normal and 8 hyperplastic. In the castrated group, 6 dogs were left untreated while androgens and estrogens were administered to 7 dogs, each. Human prostates were from 48 prostate cancer patients; half of them were submitted to androgen ablation prior to prostatectomy. The density of serotonin-positive NE cells was expressed relatively to the number of acini. RESULTS: Serotonin-positive NE cells were morphologically similar in dog and human prostates and identified in all groups, independent of the hormonal status. NE cell densities were within the same range in normal and hyperplastic dog prostates but significantly higher after castration. Androgens and estrogens after castration restored NE cell density to normal values and induced luminal differentiation and basal metaplasia, respectively. In human, the density of serotonin-positive NE cells was also significantly higher in benign glands after androgen ablation. CONCLUSIONS: The dog is a suitable animal model and mimics the human, since androgen ablation favored prostatic NE differentiation in both species. The down-regulation elicited by steroids suggests that the process may be reversible and hormonally-repressed.     

Thyrotropin-releasing hormone (TRH) activates the adenylyl cyclase of nonsecretory cells in the rat ventral prostate

Prostatic secretory and basal or stem cells were isolated from rat ventral prostate lobes by collagenase dispersion and density centrifugation in a Percoll gradient. The membrane-bound adenylyl cyclase of secretory cells could be activated in a dose-dependent manner by vasoactive intestinal peptide (VIP ED₅₀ 10^?7M) but not thyrotropin-releasing hormone (TRH). Conversely, only TRH could significantly stimulate the adenylyl cyclase in basal cell membranes (ED₅₀ 5 × 10^?7). In two separate studies enzyme activity was stimulated seven- and 13-fold by this peptide. This action of TRH on prostatic basal cells supports previous reports that high levels of immunologically active TRH have been found in prostate tissue and that TRH stimulates the growth of prostatic cancer cells in vitro.     

Selective capture of prostatic basal cells and secretory epithelial cells for proteomic and genomic analysis

Basal cells play an undefined role in signaling the growth and differentiation of normal secretory epithelial cells in the human prostate. Because basal cells disappear during malignant transformation, we hypothesize that loss of basal cell function may have a permissive role in progression of prostate intraepithelial neoplasia into invasive carcinoma. We describe an immuno-laser capture microdissection approach to selectively capture basal cells. Using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry, we identified several protein candidates selectively expressed in microdissected basal cells. We also demonstrate that the RNA derived form this technique is an excellent source for gene-array studies. Thus, we provide evidence that proteomic and microgenomic techniques can be successfully applied to investigate the expression profiles of basal and secretory cells after immuno-capture.     

Regional variations in the testicular dependence of prolactin binding and its possible relationship to castration-induced involution in rat prostate gland

Prolactin binding sites of ventral, lateral, and dorsal lobes of rat prostate were examined immunohistochemically 1, 2, 4, and 8 days after castration or sham operation. In sham-operated rats each lobe exhibited a distinct pattern of intracellular and intraluminal prolactin binding. A loss in prolactin binding from epithelial cells of ventral prostate, which was visualized postcastration, was quantitated with the aid of an image analyzer and then statistically evaluated. The proportion of ventral prostate epithelial cells devoid of prolactin binding increased from approximately 13% in sham-operated rats to approximately 29% 1 day after castration, and reached a peak level of about 71% 4 days postcastration. No loss of prolactin binding was evident in either lateral or dorsal prostate up to 8 days postcastration. Direct measurement of epithelial cell heights and subsequent statistical evaluation revealed similar regional differences in the rates and extent of prostate involution. Eight days after castration ventral prostate epithelial cell heights decreased by 56% whereas lateral and dorsal lobe epithelial cells heights decreased about 25% and 14%, respectively. The apparent relationship between testicular dependence of prostatic prolactin binding and castration-induced prostatic involution are discussed in terms of possible regional variations in the prolactin-androgen interplay in prostate.     

去势Beagle犬前列腺增生模型的建立

目的 :利用Beagle犬建立前列腺增生模型。　方法 :2年龄雄性Beagle犬 2 4只 ,随机分成对照组和 3个剂量的实验组共 4组 ,每组 6只 ,去势 2个月后 ,肌注给药。实验组分别给予丙酸睾酮 (TP) 0 .8、2 .5、7.5mg/kg ,对照组给予等体积溶剂。 2个月后 ,处死 12只动物 ,取前列腺组织 ,称重测量体积 ,放免法测定血清及前列腺组织中双氢睾酮 (DHT)水平 ,组织切片观察前列腺腺腔面积及腺上皮细胞高度。B超测量去势前、后 2个月及给予TP 2个月时犬前列腺体积。　结果 :B超结果显示 ,去势 2个月后 ,各组犬前列腺体积较去势前均明显缩小 (P均 <0 .0 1) ;给予TP 2个月后 ,各实验组犬前列腺体积明显大于对照组 (P均 <0 .0 1)。各实验组犬前列腺湿重及实际体积与对照组相比 ,均明显增重增大 (P均 <0 .0 5 ) ,并存在剂量依赖关系。犬血清及前列腺中DHT含量随TP剂量的增大而增加。显微图像分析结果显示 ,犬前列腺腺腔面积随TP剂量增大而增加 ,腺上皮细胞高度也随TP剂量增大而增高。　结论 :给予去势Beagle犬TP 2个月后 ,可成功建立前列腺增生模型。