Intensity Of Androgen Receptor Staining Research Articles

The Clinical Importance of Androgen Receptor Status in Response to Neoadjuvant Chemotherapy in Turkish Patients with Local and Locally Advanced Breast Cancer

Purpose: To investigate whether androgen receptor (AR) status affects neoadjuvant chemotherapy (NACT) in stage II and III Turkish breast cancer patients. Methods: The histological response for breast and axilla was assessed according to the Miller-Payne grading system. In light microscopy, nuclear staining in tumor cells was evaluated, and nuclear staining above 1% was accepted as positive for AR expression. The patients were divided into 3 groups according to the intensity of AR staining: low, moderate, and high. Results: In total, 71 women with breast cancer were included in the study. In univariate analysis, age, menopause status, tumor diameter, stage, histological grade, Ki-67, estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER-2) status were tested to determine which of these factors were associated with >90% responsiveness. AR negativity was found to be the only statistically significant factor. In multivariate analysis, AR positivity at each intensity was found to be the single important factor affecting decreasing pathologic response in patients receiving NACT for breast cancer. Conclusion: Our results show that AR positivity is associated with poor response to NACT in Turkish breast cancer patients and that AR positivity is independent of stage, hormone receptor status, HER-2 status, and disease stage.

Androgen receptor expression in preputial dartos tissue correlates with physiological androgen exposure in congenital malformations of the penis and in controls

The androgen receptor (AR) plays an important role in the development of male genitalia, and impaired androgen signalling has been hypothesised to underlie congenital penile malformations (CPM) such as hypospadias. Previous studies exploring the role of AR expression in the development of CPM have yielded conflicting results. To assess AR expression in human foreskin of boys/men born with hypospadias, buried penis versus controls. Foreskin samples of 428 boys and men undergoing primary penile surgery (198 controls, 197 hypospadias, and 33 buried penis) were collected between October 2013 and July 2018. AR staining was performed in all samples and semi-quantitatively scored by two researchers independently, using a modified quick score (mQuicks) that assesses the proportion and intensity of AR staining in smooth muscle fibres. The interobserver variability of the mQuicks had a high level of agreement for the total score, as well as for the subscores. Two phases of high AR expression were observed in all groups, the first following the postnatal gonadotropin surge (i.e., mini-puberty) and the second in (pre-) puberty. No differences in AR expression were found in hypospadias or buried penis cases as compared to controls matched for age at time of surgery. This study describes the physiological evolution in AR expression in the human foreskin of boys with CPM and explains the cause of the previously reported, conflicting results. Despite the very large cohort, the limitations of this study are the low number of cases younger than sixmonthsat the time of surgery and the lack of Tanner stages to correlate with the mQuicks in adolescents. The mQuicks is a straightforward and informative tool to semi-quantitatively assess AR expression in the dartos tissue. In this study, AR expression in human foreskin shows a bimodal distribution in boys with CMP and controls, following physiological androgen exposure. No statistically significant difference in AR expression could be found between both groups. Whether other local mechanisms are affected by these physiological changes is currently unclear. However, strict age-matching should be considered when exploring the mechanisms underlying disturbed penile and urethral development in CMP.

Role of androgen receptor in prostatic neoplasia versus hyperplasia.

Androgens play a fundamental role in the growth, differentiation, and maintenance of prostate tissue. The objective of the study was to evaluate and compare the androgen receptor (AR) expression in benign prostatic hyperplasia (BPH), prostatic intraepithelial neoplasia (PIN), and prostatic adenocarcinoma. A relationship between the Gleason score and AR expression was also determined in cases of prostatic adenocarcinoma. A total of 25 cases were collected which included 10 cases of prostatic adenocarcinoma, 10 cases of BPH, and five cases of PIN. Histopathological evaluation was done to determine the type of lesion including Gleason scoring. Immunohistochemistry (IHC) was performed for AR using monoclonal anti-AR antibody. Specific AR immunostaining was present in all 25 cases in varying intensity. The staining was more intense in cases of adenocarcinoma and PIN as compared BPH. There was no significant statistical difference in the intensity of staining of AR. The Gleason score was inversely related to the intensity of AR staining in adenocarcinoma. There was no significant statistical association between the AR expression and tumor, necrosis, metastasis (TNM) stage. AR nuclear expression is present in benign and malignant prostatic epithelium. In this study, cases of prostate cancer demonstrated a higher staining intensity for AR when compared with BPH. The intensity of AR staining in prostate cancer significantly reduces as the Gleason grade of the tumor increases. The staining intensity for AR was heterogeneous specifically in cases of prostate cancer. Our results indicate that AR maybe considered as a prognostic marker in prostate cancer.

Co‐assessment of cytoplasmic and nuclear androgen receptor location in prostate specimens: potential implications for prostate cancer development and prognosis

To address, by co-assessing cytoplasmic and nuclear androgen receptor (AR) expression in prostate tissues, the contribution of the AR throughout the stages of prostate cancer (PC) and its value as a marker for predicting biochemical recurrence (BCR) after radical prostatectomy (RP). Archival prostate specimens from patients who were cancer-free (43), with hormone-sensitive prostate cancer (HSPC, 62), and with androgen-independent prostate cancer (AIPC, 30) were used to construct tissue microarrays (total 135). Prostatic intraepithelial neoplasia (PIN) and non-neoplastic tissues (NA) found adjacent to HSPC were also included. Nuclear and cytoplasmic AR expression was scored by two observers using a composite scale, after immunohistochemical detection of the AR. The nuclear/cytoplasmic AR expression ratio was also calculated. Univariate Kaplan-Meier plots, and multivariate Cox and survival-tree analyses, were then used to assess the ability of the AR to predict BCR in the patients with HSPC. There was markedly greater nuclear AR staining intensity in NA than in normal prostate tissues from cancer-free patients. Cytoplasmic AR expression was highest in AIPC and markedly more than in HSPC. The nuclear/cytoplasmic AR expression ratio was highest in NA and PIN. In univariate analyses, a low nuclear AR, low cytoplasmic AR, and a high nuclear/cytoplasmic AR expression ratio were associated with BCR. Although cytoplasmic AR was an independent predictor of BCR in a Cox multivariate model (hazard ratio 2.736, 95% confidence interval 1.228-6.091, P = 0.014), survival-tree analyses suggested a complex relationship between AR expression and clinicopathological features. We propose that increased nuclear AR expression might be a precursor to PC and that cytoplasmic AR could contribute to the AIPC phenotype. The predictive ability of the AR might be closely linked to clinicopathological features.

Immunohistochemical Localization of Androgen Receptor in Two Subpopulations of Porcine Granulosa Cells In Vitro

In the ovarian follicles of mammals, androgens are utilized as substrates for estrogen synthesis or can act via androgen receptor (AR). Within the ovary, granulosa cells generally display the strongest immunoreactivity for AR protein. Therefore, the aim of the present study was to analyse possible changes in the intensity of AR staining in cultured mural and antral granulosa cells isolated from follicles at various stages of development. Porcine ovaries were obtained at a local slaughterhouse and the follicles were classified as small, medium and large dependently on their diameter. Isolated granulosa cells were separated into two populations, mural and antral, and then the cells were cultured during 48 h. After this time the cells were fixed and immunostained to visualize the AR. Androgen receptor immunostaining was detected in both, antral and mural granulosa cell cultures isolated from follicles at all stages of the development. In the mural granulosa cultures the immunostaining was comparatively weaker than that in the antral granulosa cells originating from all types of follicles. Our results provide immunohistochemical evidence that antral granulosa layer is the main site of AR immunoexpression.

Intensity of Androgen and Epidermal Growth Factor Receptor Immunoreactivity in Samples of Radical Prostatectomy as Prognostic Indicator: Correlation With Clinical Data of Long-Term Observations

We analyzed the potential prognostic significance of the immunohistochemical expression of androgen and growth factor receptors determined in prostatectomy specimens of patients with prostate cancer. A cohort of 211 patients with locally confined prostate cancer treated with radical prostatectomy with or without antiandrogen pretreatment between January 1, 1990 and August 31, 1996 was observed prospectively. Prostatectomy samples were processed immunohistochemically to visualize androgen and growth factor receptors, of which immunoreaction intensity was scored relative to that of positive control tissue. Clinical postoperative data were processed using the Kaplan-Meier method, log rank test, and univariate and multivariate explorative Cox modeling to evaluate the contribution to overall and relapse-free survival. There were statistical dependencies between the androgen receptor and epidermal growth factor receptor staining indexes. Following data stratification according to the epidermal growth factor receptor staining index the prognosis associated with a low androgen receptor staining index was worse than that with a higher androgen receptor staining index. Cox regression analysis for relapse-free survival confirmed that the risk factors low androgen receptor and increased epidermal growth factor receptor staining were associated with significantly increased relative risk. Univariate Kaplan-Meier analysis showed that patients with grade 3 carcinoma had a worse prognosis than those with better differentiated carcinoma, whereas antiandrogen pretreatment had no influence on overall survival or relapse-free survival. Using a multivariate proportional hazards regression model for data on a cohort of 211 patients with 68 showing relapse/progress or death from disease a low intensity of androgen receptor staining indicated a poor prognosis.

Androgen receptor expression in sertoli cells as a function of seminiferous tubule maturation in the human cryptorchid testis.

Androgen receptor (AR) immunohistochemistry was performed in an archival collection of adult human cryptorchid testes to determine whether AR cellular distribution and intensity of immunostaining were functions of the severity of cellular dysgenesis. The seminiferous tubule histology of cryptorchid testes collected from adults is marked by three specific patterns. 1) Seminiferous tubules are characterized as maintaining focal areas of germinal cell differentiation (albeit incomplete) that are interspersed with 2) tubules composed of Sertoli cells only, these latter cells being principally of the adult type, although dysgenetic and immature Sertoli cells may also be detected. 3) In contrast, there is a class of tubule that is characterized as being composed exclusively of Sertoli cells that are extremely dysgenetic in appearance. The majority of adult-type Sertoli cells found in the first types of tubules exhibited either robust or moderate AR staining intensity. Peritubular cells of these tubules also expressed a similar AR staining intensity. In contrast, in the more dysgenetic and immature type Sertoli cells found in the second type of tubules, the intensity of AR staining was significantly less, if not missing altogether. Finally, in the most dysgenetic tubules, Sertoli cell AR staining was never detected. To our knowledge, this is the first report in the literature that addresses the intensity of AR immunostaining in Sertoli cells of cryptorchid testes. The results presented herein are consistent with the interpretation that the intensity of AR staining in Sertoli cells diminishes as a function of the severity to which the cells are afflicted within a cryptorchid testis and that focal absence of AR expression in Sertoli cells correlates with a lack of local spermatogenesis in the tubules.

Androgen receptor distribution in adult human testis.

The distribution of the androgen receptor (AR) in archival human testes was determined immunocytochemically using an affinity-purified peptide-specific rabbit antibody, PG21, and employing a modified biotin-streptavidin-immunoperoxidase method that incorporated a biotin amplification step. In combination with microwave epitope retrieval, the biotin amplification step increased the sensitivity of the immunostaining assay approximately 20-fold. Thus, the useful range at which PG21 rendered a robust, specific immunostaining signal without also increasing nonspecific background was extended dramatically. Broadening the useful range of the PG21 antibody made it possible to resolve the relative amounts of immunopositive AR in different cell types of the human testis. At a high PG21 concentration, for example, all AR-positive cells exhibited a robust immunostaining intensity, but it was not possible to distinguish between nuclei exhibiting either high or moderate immunostaining intensities. In contrast, as the concentration of PG21 was decreased, distinct populations of testicular cells exhibited differential AR immunostaining intensities in their nuclei. AR immunostaining of Sertoli cell nuclei was present at low PG21 concentrations at which no immunostaining of peritubular myoid cells or Leydig cells could be detected. In turn, AR immunostaining of peritubular myoid cells was detected at PG21 concentrations that did not immunostain Leydig cells. Moreover, within the seminiferous epithelium, Sertoli cell nuclear AR staining intensity was less at stages V and VI of the cycle of the seminiferous epithelium than that at stage III, and stage III staining intensity was greater than that at stages I and II. This AR immunostaining pattern in human Sertoli cell nuclei as a function of the cycle of the seminiferous epithelium is reminiscent of the pattern observed in rodent species. Finally, no AR immunostaining of germ cells was observed at any of the PG21 concentrations examined.

In Uteroand Lactational Exposure of the Male Rat to 2,3,7,8-Tetrachlorodibenzo-p-dioxin Impairs Prostate Development: 2. Effects on Growth and Cytodifferentiation

In the male Holtzman rat,in uteroand lactational 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure decreases prostate weight without inhibiting testicular androgen production or decreasing circulating androgen concentrations. Therefore, the present study sought to characterize effects of TCDD exposure on prostate development, from very early outgrowth from the urogenital sinus (Gestation Day [GD] 20) until rapid growth and differentiation are essentially complete (Postnatal Day [PND] 32). Pregnant Holtzman rats were administered a single dose of TCDD (1.0 μg/kg po) or vehicle on GD 15 and offspring were exposed via placental transfer (GD 20 euthanasia) or placental and subsequent lactational transfer until euthanasia (if before PND 21) or weaning. Results show that the prostatic epithelial budding process was impaired byin uteroTCDD exposure, as evidenced by significant decreases in the number of buds emerging from dorsal, lateral, and ventral aspects of the GD 20 urogenital sinus. Ventral prostate cell proliferation index was significantly decreased on PND 1 but was similar to or higher than control at later times, whereas apoptosis was an extremely rare event in ventral prostates from both control and TCDD-exposed animals. Delays were noted in the differentiation of pericordal smooth muscle cells and luminal epithelial cells. In addition, ventral prostates from approximately 40% of TCDD-exposed animals examined on PNDs 21 and 32 exhibited alterations in the histological arrangement of cell types that could not be explained by a developmental delay. Compared to controls, these ventral prostates exhibited a disorganized, hyperplastic epithelium containing fewer luminal epithelial cells and an increased density or continuous layer of basal epithelial cells, as well as thicker periductal smooth muscle sheaths. In addition, in ventral prostates from TCDD-exposed animals, the intensity of androgen receptor staining was relatively low in the central and distal epithelium, and the number of androgen receptor-positive cells was relatively high in the periductal stroma. These data suggest thatin uteroand lactational TCDD exposure interferes with prostate development by decreasing very early epithelial growth, delaying cytodifferentiation, and, in the most severely affected animals, producing alterations in epithelial and stromal cell histological arrangement and the spatial distribution of androgen receptor expression that may be of permanent consequence.

The developmental pattern of androgen receptor expression in rat prostate lobes is altered after neonatal exposure to estrogen

Brief administration of estrogen to newborn rats permanently imprints adult prostatic androgen receptor (AR) expression in a lobe-specific manner. To delineate this effect, we examined the immediate effects of early estrogen exposure on the changing AR pattern in the developing ventral, dorsal, and lateral prostate lobes. Antibodies against rat AR (PG-21) were used in combination with several antibodies to cell-specific antigens for positive cellular identification by immunocytochemistry. At birth, mesenchymal cells of the ventral prostate were strongly AR positive (AR+). Epithelial cells stained only for basal cell cytokeratins and, in contrast to earlier reports, many were AR+ on day 1. Between days 3-5, periductal mesenchymal cells differentiated into smooth muscle cells which retained strong AR+ staining, whereas interductal fibroblasts exhibited a decreased incidence of AR+ cells. Between days 5-10, luminal epithelial cells first appeared, and a striking increase in AR staining intensity was noted relative to that in the basal cells. During puberty, basal cells lost their AR immunoreactivity. Similar changes were observed in the dorsal and lateral lobes. Newborn rats were given 25 micrograms estradiol benzoate on days 1, 3, and 5 and were killed thereafter. By day 6, AR staining was markedly decreased to a weak to moderate intensity in all cell types, and by day 10, AR was virtually absent in the separate lobes. Growth and epithelial cytodifferentiation were significantly retarded. Between days 15-30, evidence of luminal cell cytodifferentiation was noted; however, this was frequently not associated with an increase in AR staining. In the ventral and dorsal lobes, a continuous peripheral layer of AR-negative basal cells surrounded the ducts in the central and proximal regions, and this was associated with a permanent inability of luminal epithelial cells to express AR. Epithelial and smooth muscle AR expression was observed only in the distal tips. In contrast, AR expression rapidly returned in all regions of the lateral lobes, except the proximal ducts. We conclude that 1) basal epithelial cells express AR as early as day 1 of life and should be considered as possible direct targets of androgen action during prostate morphogenesis; 2) differentiation into luminal cells is associated with an increase, rather than an induction, of AR expression; and 3) periductal smooth muscle cells retain strong AR expression throughout development and should be considered primary targets for androgen-mediated morphogenesis. Neonatal estrogen initially down-regulates AR expression in all cells of three lobes, which may explain the overall growth retardation.

The developmental pattern of androgen receptor expression in rat prostate lobes is altered after neonatal exposure to estrogen.

Brief administration of estrogen to newborn rats permanently imprints adult prostatic androgen receptor (AR) expression in a lobe-specific manner. To delineate this effect, we examined the immediate effects of early estrogen exposure on the changing AR pattern in the developing ventral, dorsal, and lateral prostate lobes. Antibodies against rat AR (PG-21) were used in combination with several antibodies to cell-specific antigens for positive cellular identification by immunocytochemistry. At birth, mesenchymal cells of the ventral prostate were strongly AR positive (AR+). Epithelial cells stained only for basal cell cytokeratins and, in contrast to earlier reports, many were AR+ on day 1. Between days 3-5, periductal mesenchymal cells differentiated into smooth muscle cells which retained strong AR+ staining, whereas interductal fibroblasts exhibited a decreased incidence of AR+ cells. Between days 5-10, luminal epithelial cells first appeared, and a striking increase in AR staining intensity was noted relative to that in the basal cells. During puberty, basal cells lost their AR immunoreactivity. Similar changes were observed in the dorsal and lateral lobes. Newborn rats were given 25 micrograms estradiol benzoate on days 1, 3, and 5 and were killed thereafter. By day 6, AR staining was markedly decreased to a weak to moderate intensity in all cell types, and by day 10, AR was virtually absent in the separate lobes. Growth and epithelial cytodifferentiation were significantly retarded. Between days 15-30, evidence of luminal cell cytodifferentiation was noted; however, this was frequently not associated with an increase in AR staining. In the ventral and dorsal lobes, a continuous peripheral layer of AR-negative basal cells surrounded the ducts in the central and proximal regions, and this was associated with a permanent inability of luminal epithelial cells to express AR. Epithelial and smooth muscle AR expression was observed only in the distal tips. In contrast, AR expression rapidly returned in all regions of the lateral lobes, except the proximal ducts. We conclude that 1) basal epithelial cells express AR as early as day 1 of life and should be considered as possible direct targets of androgen action during prostate morphogenesis; 2) differentiation into luminal cells is associated with an increase, rather than an induction, of AR expression; and 3) periductal smooth muscle cells retain strong AR expression throughout development and should be considered primary targets for androgen-mediated morphogenesis. Neonatal estrogen initially down-regulates AR expression in all cells of three lobes, which may explain the overall growth retardation.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunohistochemistry of the Androgen Receptor in Human Benign and Malignant Prostate Tissue

The role of the androgen receptor in the development and progression of prostatic carcinoma has not been defined. The development of androgen receptor antibodies has provided new opportunities for direct immunohistochemical analysis. We compared the androgen receptor staining characteristics of fresh human prostatic carcinoma with benign prostatic hyperplasia (BPH) using an avidinbiotin complex method. Cancer and BPH obtained from the same radical retropubic prostatectomy specimen in 10 prostate cancer patients (68.5 ± 7.3 years old standard deviation) and BPH from 10 noncancer patients (71.5 ± 7.7 years old) were incubated with AR52, a rabbit polyclonal antibody against a synthetic androgen receptor peptide. Nuclei within each section were graded for intensity of androgen receptor staining (0—absent, 1—weak, 2—moderate or 3—strong) and the percentage (0 to 100%) of nuclei sampled staining at each of these intensity levels was determined. A total intensity score (0 to 300) was the summation of the products of each intensity score (0 to 3) and their corresponding percentages. Cancer sections (166 ± 69) stained less intensely and more heterogeneously than BPH in cancer patients (246 ± 41, Student’s t test p <0.05) and noncancer patients (225 ± 39, p <0.05). The decreased intensity and greater heterogeneity of androgen receptor staining in cancer tissue may implicate a quantitative or functional difference in androgen receptor between prostatic carcinoma and BPH.

Image analysis of androgen receptor immunostaining in metastatic prostate cancer heterogeneity as a predictor of response to hormonal therapy

Reliable predictors of the response of prostate cancer to androgen ablation therapy are lacking. The goals of this study were to determine whether nuclear androgen receptor (AR) concentrations in metastatic prostate cancer varied within and between specimens and to correlate this information with the response to therapy. AR concentration was evaluated by computer-assisted image analysis of immunohistochemical staining intensity in 200 malignant epithelial nuclei of each of 17 specimens of Stage D2 prostate cancer obtained before hormonal therapy. The data were correlated with the time to tumor progression (relapse) after hormonal therapy. AR staining intensity varied within specimens, and the variance of staining intensity was significantly greater (P = 0.03) in the poor responders (n = 8; time to progression, < 20 months) than in the good responders (n = 9; time to progression, > or = 20 months). The kurtosis was significantly lower in poor responders (P = 0.04). However, the mean AR staining intensity was not significantly different among patients. The frequency distribution plots of good responders were generally uniform and unimodal, but those of poor responders were flattened (more platykurtic), dispersed, and highly variable. Thus, the AR concentration per cell was significantly more heterogeneous in poor responders. Variance was a significant predictor of response. Five of 6 patients with a high variance (defined as variance greater than the mean) were poor responders, whereas 8 of 11 patients with a low variance were good responders (an overall classification accuracy of 13 of 17, 76%). The greater AR heterogeneity in poor responders may reflect a greater genetic instability in tumors that have progressed further toward androgen independence and may be a valuable predictor of progression.

Growth response and androgen receptor expression in seminal vesicles from aging transgenic mice expressing human or bovine growth hormone genes.

Previous work has shown that expression of human (h) GH in transgenic mice is associated with significant age-related enlargement of seminal vesicles. To further explore this aberrant growth activity, we have characterized seminal vesicles from various GH transgenic lines and examined their androgen receptor (AR) content and distribution. Six groups of animals were initially studied: young adult (3-5 months) control mice, old (greater than 12 months) control mice, young adult hGH transgenic mice, old hGH transgenics, young adult bovine (b) GH transgenics, and old bGH transgenic mice. Young transgenic mice (hGH and bGH) possessed seminal vesicles with similar relative weights, DNA and protein contents, and AR levels as nontransgenic littermates. Histologically, the glands appeared similar. With aging, the hGH transgenic seminal vesicles exhibited massive stromal hyperplasia, whereas the glands from controls and bGH transgenic mice did not show this response. Seminal vesicles from old hGH mice presented with a marked increase in cell number (DNA content) and a marked decrease in cell size and/or glandular secretions (protein/DNA ratio) compared to those from old controls and young hGH transgenic mice. Tissue AR content was markedly reduced in old hyperplastic hGH seminal vesicles compared to that in seminal vesicles from young hGH transgenics, old controls, and old bGH transgenic mice. Immunohistochemistry indicated the absence of AR in the proliferating stromal cells, whereas acinar epithelial cells showed similar or moderately reduced AR staining intensity compared to control seminal vesicles. To examine whether the above results may be due to insertional mutagenesis rather than hGH itself, two additional GH transgenic lines were examined. Aged transgenic mice expressing bGH with an alternate promoter possessed seminal vesicle weights that were not different from those of old controls, whereas aged transgenic mice expressing an hGH. V gene (variant gene, placental origin) possessed significantly larger vesicles than the controls, which further suggests that vesicular hyperplasia is specifically related to hGH. To assess androgen responsiveness, aged control and hGH transgenic mice were castrated and examined after 15 days. While control seminal vesicles significantly decreased in size, glands from transgenic mice did not. Regressive changes were observed in the remaining epithelium of hGH transgenic mice; however, stromal tissue exhibited no response to androgen withdrawal. The present results suggest that the aging-associated seminal vesicle hyperplasia in hGH transgenic mice is a result of a massive increase in stromal tissue that is low or devoid of AR, suggesting a loss of direct androgen regulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Growth response and androgen receptor expression in seminal vesicles from aging transgenic mice expressing human or bovine growth hormone genes

Previous work has shown that expression of human (h) GH in transgenic mice is associated with significant age-related enlargement of seminal vesicles. To further explore this aberrant growth activity, we have characterized seminal vesicles from various GH transgenic lines and examined their androgen receptor (AR) content and distribution. Six groups of animals were initially studied: young adult (3-5 months) control mice, old (greater than 12 months) control mice, young adult hGH transgenic mice, old hGH transgenics, young adult bovine (b) GH transgenics, and old bGH transgenic mice. Young transgenic mice (hGH and bGH) possessed seminal vesicles with similar relative weights, DNA and protein contents, and AR levels as nontransgenic littermates. Histologically, the glands appeared similar. With aging, the hGH transgenic seminal vesicles exhibited massive stromal hyperplasia, whereas the glands from controls and bGH transgenic mice did not show this response. Seminal vesicles from old hGH mice presented with a marked increase in cell number (DNA content) and a marked decrease in cell size and/or glandular secretions (protein/DNA ratio) compared to those from old controls and young hGH transgenic mice. Tissue AR content was markedly reduced in old hyperplastic hGH seminal vesicles compared to that in seminal vesicles from young hGH transgenics, old controls, and old bGH transgenic mice. Immunohistochemistry indicated the absence of AR in the proliferating stromal cells, whereas acinar epithelial cells showed similar or moderately reduced AR staining intensity compared to control seminal vesicles. To examine whether the above results may be due to insertional mutagenesis rather than hGH itself, two additional GH transgenic lines were examined. Aged transgenic mice expressing bGH with an alternate promoter possessed seminal vesicle weights that were not different from those of old controls, whereas aged transgenic mice expressing an hGH. V gene (variant gene, placental origin) possessed significantly larger vesicles than the controls, which further suggests that vesicular hyperplasia is specifically related to hGH. To assess androgen responsiveness, aged control and hGH transgenic mice were castrated and examined after 15 days. While control seminal vesicles significantly decreased in size, glands from transgenic mice did not. Regressive changes were observed in the remaining epithelium of hGH transgenic mice; however, stromal tissue exhibited no response to androgen withdrawal. The present results suggest that the aging-associated seminal vesicle hyperplasia in hGH transgenic mice is a result of a massive increase in stromal tissue that is low or devoid of AR, suggesting a loss of direct androgen regulation.