Androgen depletion up‐regulates cadherin‐11 expression in prostate cancer

Men with castration‐resistant prostate cancer (PCa) frequently develop metastasis in bone. The reason for this association is unclear. We have previously shown that cadherin‐11 (also known as OB‐cadherin), a homophilic cell adhesion molecule that mediates osteoblast adhesion, plays a role in the metastasis of PCa to bone. Here, we report that androgen‐deprivation therapy up‐regulates cadherin‐11 expression in PCa. In human PCa specimens, immunohistochemical staining showed that 22/26 (85%) primary PCa tumours from men with castration‐resistant PCa expressed cadherin‐11. In contrast, only 7/50 (14%) androgen‐dependent PCa tumours expressed cadherin‐11. In the MDA–PCa‐2b xenograft animal model, cadherin‐11 was expressed in the recurrent tumours following castration. In the PCa cell lines, there is an inverse correlation between expression of cadherin‐11 and androgen receptor (AR), and cadherin‐11 is expressed in very low levels or not expressed in AR‐positive cell lines, including LNCaP, C4‐2B4 and VCaP cells. We showed that AR likely regulates cadherin‐11 expression in PCa through an indirect mechanism. Although re‐expression of AR in the AR‐negative PC3 cells led to the inhibition of cadherin‐11 expression, depletion of androgen from the culture medium or down‐regulation of AR by RNA interference in the C4‐2B4 cells or VCaP cells only produced a modest increase of cadherin‐11 expression. Promoter analysis indicated that cadherin‐11 promoter does not contain a typical AR‐binding element, and AR elicits a modest inhibition of cadherin‐11 promoter activity, suggesting that AR does not regulate cadherin‐11 expression directly. Together, these results suggest that androgen deprivation up‐regulates cadherin‐11 expression in prostate cancer, and this may contribute to the metastasis of PCa to bone. Our study suggests that therapeutic strategies that block cadherin‐11 expression or function may be considered when applying androgen‐ablation therapy. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Genome‐Wide Association Study Confirms SNPs in SNCA and the MAPT Region as Common Risk Factors for Parkinson Disease

Parkinson disease (PD) is a chronic neurodegenerative disorder with a cumulative prevalence of greater than one per thousand. To date three independent genome‐wide association studies (GWAS) have investigated the genetic susceptibility to PD. These studies implicated several genes as PD risk loci with strong, but not genome‐wide significant, associations. In this study, we combined data from two previously published GWAS of Caucasian subjects with our GWAS of 604 cases and 619 controls for a joint analysis with a combined sample size of 1752 cases and 1745 controls. SNPs in SNCA (rs2736990, p‐value = 6.7 × 10^?8; genome‐wide adjusted p = 0.0109, odds ratio (OR) = 1.29 [95% CI: 1.17–1.42] G vs. A allele, population attributable risk percent (PAR%) = 12%) and the MAPT region (rs11012, p‐value = 5.6 × 10^?8; genome‐wide adjusted p = 0.0079, OR = 0.70 [95% CI: 0.62–0.79] T vs. C allele, PAR%= 8%) were genome‐wide significant. No other SNPs were genome‐wide significant in this analysis. This study confirms that SNCA and the MAPT region are major genes whose common variants are influencing risk of PD.     

New Therapeutic Approach to Suppress Castration-Resistant Prostate Cancer Using ASC-J9 via Targeting Androgen Receptor in Selective Prostate Cells

Using androgen receptor (AR) knockout mice to determine AR functions in selective prostate cancer (PCa) cells, we determined that AR might play differential roles in various cell types, either to promote or suppress PCa development/progression. These observations partially explain the failure of current androgen deprivation therapy (ADT) to reduce/prevent androgen binding to AR in every cell. Herein, we identified the AR degradation enhancer ASC-J9, which selectively degrades AR protein via interruption of the AR-AR selective coregulator interaction. Such selective interruption could, therefore, suppress AR-mediated PCa growth in the androgen-sensitive stage before ADT and in the castration-resistant stage after ADT. Mechanistic dissection suggested that ASC-J9 could activate the proteasome-dependent pathway to promote AR degradation through the enhanced association of AR-Mdm2 complex. The consequences of ASC-J9-promoted AR degradation included reduced androgen binding to AR, AR N-C terminal interaction, and AR nuclear translocation. Such inhibitory regulation could then result in suppression of AR transactivation and AR-mediated cell growth in eight different mouse models, including intact or castrated nude mice xenografted with androgen-sensitive LNCaP cells or androgen-insensitive C81 cells and castrated nude mice xenografted with castration-resistant C4-2 and CWR22Rv1 cells, and TRAMP and Pten^+/− mice. These results demonstrate that ASC-J9 could serve as an AR degradation enhancer that effectively suppresses PCa development/progression in the androgen-sensitive and castration-resistant stages.Androgen/androgen receptor (AR) signaling plays essential roles in prostate cancer (PCa) progression and results in castration resistance.^1–4 Currently, most, if not all, androgen deprivation therapy (ADT) targets androgens via surgical and/or medical castration to reduce/prevent androgen binding to AR.⁵ However, few, if any, of these ADTs with various antiandrogens, including the recently developed enzalutamide,⁶ have the capacity to eliminate all PCa cells in the later castration-resistant stage. Therefore, degradation of AR during/after ADT can be considered to have clinical benefits for patients with advanced PCa with substantial AR.⁶ These conclusions suggest that identifying a novel compound(s) that could degrade/diminish AR protein in the castration-resistant stage, unlike currently used antiandrogens, may yield better therapeutic efficacies to battle PCa in the castration-resistant stage.Early studies via isolation of three PCa primary cells (PCa1, PCa2, and PCa3) from the same patient found that androgen/AR signaling could function differentially to either suppress or promote PCa growth.⁷ Using the cre-loxP strategy in mice to selectively knockout AR in various PCa cells, Niu and colleagues^3,4,8 observed that the loss of AR in cytokeratin 5/cytokeratin 8–positive basal intermediate epithelial cells led to increased PCa metastasis, yet loss of AR in cytokeratin 8–positive luminal epithelial cells resulted in suppressed PCa progression with increased cell apoptosis. In contrast, loss of AR in stromal fibroblasts and smooth muscle cells resulted in suppression of prostate/PCa growth.^9,10 These results conclude that AR can either promote or suppress PCa progression in different types of PCa cells.Because only one AR gene has been identified,¹¹ we hypothesized that these differential AR roles in various PCa cells in the same patient could be due to the existence of different AR-AR coregulator complexes. This hypothesis led us to screen the AR degradation enhancer 5-hydroxy-1,7-bis(3,4-dimethoxyphenyl)-1,4,6-heptatrien-3-one (ASC-J9) from natural products and their derivatives by selectively interrupting the interaction between AR and selective AR coregulators, such as AR–AR-associated protein (ARA) 70 and AR-ARA55, which are expressed mainly in luminal epithelial cells and stromal cells, respectively, in which AR may function with positive roles to either maintain cell survival or promote cell proliferation. Results from four different human PCa cell lines and eight different in vivo mouse models concluded that ASC-J9 could function as a promising AR degradation enhancer to suppress PCa progression before and after castration resistance with few adverse effects.     

Stromal Androgen Receptor Roles in the Development of Normal Prostate,Benign Prostate Hyperplasia,and Prostate Cancer

The prostate is an androgen-sensitive organ that needs proper androgen/androgen receptor (AR) signals for normal development. The progression of prostate diseases, including benign prostate hyperplasia (BPH) and prostate cancer (PCa), also needs proper androgen/AR signals. Tissue recombination studies report that stromal, but not epithelial, AR plays more critical roles via the mesenchymal-epithelial interactions to influence the early process of prostate development. However, in BPH and PCa, much more attention has been focused on epithelial AR roles. However, accumulating evidence indicates that stromal AR is also irreplaceable and plays critical roles in prostate disease progression. Herein, we summarize the roles of stromal AR in the development of normal prostate, BPH, and PCa, with evidence from the recent results of in vitro cell line studies, tissue recombination experiments, and AR knockout animal models. Current evidence suggests that stromal AR may play positive roles to promote BPH and PCa progression, and targeting stromal AR selectively with AR degradation enhancer, ASC-J9, may allow development of better therapies with fewer adverse effects to battle BPH and PCa.The prostate contains mainly the stromal cells and epithelial cells that are separated by base members and merged in extracellular matrix. Stromal cells include fibroblasts, smooth muscle cells (SMCs), and other minor inflammatory cells, nerve cells, and endothelial cells.The prostate is developed from the endodermal urogenital sinus¹ that contains an outer layer of embryonic connective tissue urogenital sinus mesenchyme (UGM) and an inner layer of urogenital sinus epithelium (UGE).¹ The initial step of prostate development in UGM involves the differentiation of fibroblasts and SMCs,¹ and in response to the UGM androgen/androgen receptor (AR) signals, UGE can grow into the surrounding stromal cells and develop into the prostate epithelial cells as part of the normal prostate development.The ability of the UGM to induce epithelial development and the developed epithelial cells, in return, to direct UGM to undergo differentiation, suggesting that the reciprocal developmental interactions between UGM and UGE might be governed by androgen/AR signals, which are essential for the development of normal prostate, benign prostate hyperplasia (BPH), and prostate cancer (PCa). Prostate development factors, including its proliferation, differentiation, morphogenesis, and functional maintenance, are all influenced by androgen/AR signals.² Androgen/AR signals also play vital roles in the initiation and progression of BPH and PCa,^3,4 which may require the proper interaction with various AR coregulators.²AR is a member of the nuclear receptor superfamily that can be activated and translocated from cytoplasm to nucleus after binding the testosterone or dihydrotestosterone.^5–7 In prostate, AR is expressed in both epithelial and stromal tissues. The transactivated AR in nucleus may then function through modulation of various downstream target genes to influence the development and maintenance of the prostate. In addition to influencing cell growth directly, epithelial AR and stromal AR can also function through epithelial-mesenchymal transition (EMT) to influence prostate development. EMT is a process by which epithelial cells lose their cell-cell adhesion and gain migratory properties to become mesenchymal-like and/or mesenchymal stem cells. These potent mesenchymal cells may then differentiate into different cell types to influence the progression of BHP⁸ and PCa.⁹This review will focus on the discussion of the roles of stromal AR in the development of normal prostate and prostate diseases.     

Androgen receptor expression in breast cancer patients tested for BRCA1 and BRCA2 mutations

Pristauz G, Petru E, Stacher E, Geigl J B, Schwarzbraun T, Tsybrovskyy O, Winter R & Moinfar F
(2010) Histopathology 57, 877–884 Androgen receptor expression in breast cancer patients tested for BRCA1 and BRCA2 mutations Aim: To assess the expression of receptors for androgen (AR), oestrogen (ER) and progesterone (PR) as well as human epidermal growth factor receptor type 2 (Her‐2/neu) status of breast carcinomas in breast cancer susceptibility gene (BRCA) BRCA1/2 mutation carriers and BRCA1/2 negative tested women. Methods: One hundred and thirty‐five breast cancers in women tested for BRCA1/2 mutations. Screening for BRCA1 and BRCA2 mutations was performed by direct sequencing of all BRCA1 and BRCA2 exons as well as the surrounding intronic sequences. Additionally, BRCA genes were analysed with multiplex ligation‐dependent probe amplification. Consecutive paraffin sections were examined immunhistochemically for AR, ER, PR and Her‐2/neu. Results: Of the 135 tumours, 43 (32%) were BRCA1‐related, 18 (13%) were BRCA2‐related and 74 (55%) were BRCA1/2‐negative. Seventy‐two per cent of the BRCA1‐related, 22% of the BRCA2‐related and 12% of the BRCA1/2‐negative tumours were triple (ER, PR, Her2neu)‐negative. Eighty‐four per cent of BRCA1 mutated cancers were high‐grade (G3) tumours. ARs were expressed in 30% (13 of 43) of BRCA1‐related, in 78% (14 of 18) in BRCA2‐related tumours and in 76% (56 of 74) in BRCA1/2 negative tumours. Twenty‐one per cent of ER‐negative BRCA1‐related tumours expressed androgen receptors. Conclusion: Approximately one in five BRCA1 mutated breast cancers negative for ER and PR express androgen receptors. Modulation of AR might open a new avenue for treating these high‐risk cancers.     

Germ-line sequence variants of PTEN do not have an important role in hereditary and non-hereditary prostate cancer susceptibility

PTEN (phosphatase and tensin homolog deleted on chromosome 10) functions as a major tumor suppressor gene and is frequently deleted in different types of tumors including prostate cancer (PCa). It was hypothesized that germ-line genetic changes of PTEN affect susceptibility to PCa. Both common (with a minor allele frequency 5%) and rare (with a minor allele frequency <5%) germ-line variants of PTEN were comprehensively evaluated. A total of 15 germ-line variants were identified by re-sequencing the PTEN gene, including 5' untranslated region, all nine exons, exon-intron junctions and 3' untranslated region, in 188 probands of hereditary prostate cancer (HPC) families recruited from Johns Hopkins Hospital. Two microsatellite markers surrounding PTEN were used to test the co-segregation of 10 rare variants, which may give rise to highly penetrance in HPC. Two common single nucleotide polymorphisms (SNPs) were evaluated in the 188 HPC families using a family-based association study approach. To study low penetrant SNPs in PCa susceptibility, 33 SNPs covering PTEN were selected from the whole genome-wide association studies (GWAS) from our available case-control studies in Sweden (Cancer of the Prostate in Sweden (CAPS)) and the publicly available cancer genetic markers of susceptibility (CGEMS) study. Germ-line copy-number variations (CNVs) in PTEN were assessed in CAPS. Co-segregation of germ-line variants and PCa was not observed among HPC families and no significant differences in the allele frequencies were observed in sporadic cases and controls, aggressive and non-aggressive PCa (P>0.05). These results suggest that germ-line variants in PTEN do not have an important role in PCa susceptibility.     

Genotyping of AR and PSA polymorphisms in a patient with Klinefelter syndrome, non-Hodgkin lymphoma, and adenocarcinoma of the prostate

It has been hypothesized that the AR (androgen receptor) gene binds the two PSA (prostate-specific antigen) alleles with differing affinities and may differentially influence prostate cancer risk. In this article, we report a case of adenocarcinoma of the prostate in a 56-year-old man with Klinefelter syndrome (47,XXY) and non-Hodgkin lymphoma, as well as the AR and PSA genotype. AR and PSA gene polymorphisms were analyzed by polymerase chain reaction-based methods using DNA from peripheral white blood cells and the prostate cancer. We determined the methylation status of the AR gene on the X chromosome. The patient presents with the AG genotype for the ARE-1 (androgen response element) region of the PSA gene. We detect the presence of two short AR alleles with 19 and 11 CAG repeats each. Unmethylated alleles were demonstrated for both. The shorter allele was inactive in more than 60% of total DNA in both control blood and prostate cancer cells. The presence of short AR alleles and the G allele of the PSA gene may contribute to the development of prostate cancer in a 47,XXY patient.     

Meta-analysis of three polymorphisms in the steroid-5-alpha-reductase, alpha polypeptide 2 gene (SRD5A2) and risk of prostate cancer

The steroid-5-alpha-reductase, alpha polypeptide 2 (SRD5A2) gene plays a crucial role in androgen metabolism pathway in human prostate. It encodes SRD5A2 enzyme, which catalyses testosterone to dihydrotestosterone (DHT). DHT is the main active structure binding with androgen receptor (AR). After the activation of AR, it further regulates a series of target genes in androgen metabolism pathway. However, no clear consensus has been reached on the association between the SRD5A2 V89L, A49T and TA repeat polymorphisms and prostate cancer (PCa) risk. Thus, we performed a meta-analysis of 31 association studies with 14,726 PCa cases and 15,802 controls. We found no association between PCa and 89L compared with 89V allele [odds ratio (OR) = 1.02, 95% confidence interval (CI) 0.98-1.06, P(heterogeneity) = 0.44]. The 49T allele showed a significantly elevated effect on the high stage (Stages III-IV) of PCa risk both under the dominant genetic model (OR = 2.13, 95% CI 1.44-3.15, P(heterogeneity) = 0.65) and in the contrast T versus A allele (OR = 2.06, 95% CI 1.41-3.02, P(heterogeneity) = 0.69). There was a significantly decreased association between PCa and long TA repeat as compared versus short TA repeat (OR = 0.86, 95% CI 0.74-1.00, P(heterogeneity) = 0.79). No significant between-study heterogeneity was found in all subjects under four genetic models (dominant model, recessive model, allele comparison and homozygosity comparison) for these three polymorphisms, respectively, so the fixed effects model was used to pool the result. Our result indicated that carriers of 49T might improve the risk of PCa in higher stages (Stages III-IV), carriers of long TA repeat might decrease the risk of PCa and 89L may not be an important risk factor for PCa. However, due to the limited sample sizes, this meta-analysis did not achieve sufficiently conclusive results. Still more well-designed studies should be performed to clarify the role of these three polymorphisms in the development of PCa.     

South Indian men with reduced CAG repeat length in the androgen receptor gene have an increased risk of prostate cancer

The androgen receptor (AR) gene possesses polymorphic CAG tandem repeats and the repeat length has been inversely related to the risk of prostate cancer (PCa). The distinct ethnic variation in the CAG repeat length may be correlated to differences in PCa risk in different populations. To evaluate the CAG repeat length in the AR gene and the implications for PCa, we screened 87 PCa patients and 120 control subjects from South India. The mean CAG repeat length in PCa patients was significantly smaller than that of controls (17.0 vs 20.7; P<0.001). Men with 19 CAG repeats had a significantly increased risk of cancer compared to those with >19 CAG repeats (age-adjusted OR=7.01; 95% CI=3.52–13.94; P<0.001). However, no significant association was observed between CAG repeats and age of onset or prostate-specific antigen levels. Although there was a trend towards shorter CAG repeat length in high grades of cancer, it was not significant (P=0.085). Thus, our results suggest an association between short CAG repeats in the AR gene and PCa risk in South Indian men. Further, we propose that CAG repeats could be used as a prognostic marker for PCa diagnosis.     

Pleiotropic functional properties of androgen receptor mutants in prostate cancer

The androgen receptor (AR) signaling pathway plays an important role during the development of the normal prostate gland, but also during the progression of prostate cancer on androgen ablation therapy. Mutations in the AR gene emerge to keep active the AR signaling pathway and to support prostate cancer cells growth and survival despite the low levels of circulating androgens. Indeed, mutations affecting the ligand binding domain (LBD) of the AR have been shown to generate so-called "promiscuous" receptors that present widened ligand specificity and allow the stimulation of these receptors by a larger spectrum of endogenous hormones. Another class of mutations, arising in the amino-terminal domain (NTD) of the receptor, modulate AR interactions with coregulators involved in cell proliferation regulation. Besides characteristics of these well-known types of mutations, the properties of other classes of AR mutants recently described in prostate cancer are currently under investigation. Most interestingly, in addition to their potential role in the mechanisms which allow prostate cancer cells to escape androgen ablation therapy, data suggest that certain AR mutations are present early in the natural history of the disease and may play a role in many aspects of prostate cancer progression. Surprisingly, singular truncated AR devoid of their carboxy-terminal end (CTE) region seem to exert specific paracrine effects and to induce a clonal cooperation with neighboring prostate cancer cells, which may facilitate both the invasion and metastasis processes. In this article, we review the functional properties of different classes of AR mutants and their potential impact on the natural history of prostate cancer. Hum Mutat 0, 1-14, 2008. (c) 2008 Wiley-Liss, Inc.     

A New Missense Substitution at a Mutational Hot Spot of the Androgen Receptor in SiblingsWith Complete Androgen Insensitivity Syndrome

Several mutations have been described in the human androgen receptor gene including constitutional mutations in androgen insensitivity syndrome, somatic mutations in prostate cancer and triplet expansions in Kennedy's disease (Gottlieb et al. 1997). Here we report on two siblings with complete androgen insensitivity and a novel missense mutation, D695V, in their androgen receptor gene. The two XY females are siblings of German descent and presented at the ages of 23 and 19 years, respectively, with typical clinical features of complete androgen insensitivity. We found both siblings to be hemizygous for a new adenine to thymine transversion at the second nucleotide of codon 695 within the fourth exon of the human androgen receptor gene. The resulting missense mutation D695V is located at the amino-terminal border of the ligand- binding domain of the androgen receptor. The aspartic acid residue at this position is highly conserved in the steroid binding domains of other members of the nuclear receptor family and has already been found to be the site of two other missense mutations associated with androgen insensitivity syndrome (Ris Stalpers et al. 1991, Hiort et al. 1996). Three of four reported subjects showed the complete androgen insensitivity phenotype, in accordance with the two siblings in our study. We suggest that the existence of three pathological amino acid substitutions for aspartic acid 695 most likely reflects the essential role of this residue for normal androgen receptor function in male sexual differentiation.     

Overexpression and gene amplification of BAG-1L in hormone-refractory prostate cancer

BAG‐1L (Bcl‐2‐associated anthanogene 1) has been found to interact with androgen receptor (AR), and has been suggested to be involved in the development of prostate cancer. In order to determine the presence of genetic and/or expression alterations of BAG‐1L in prostate cancer, we analysed human prostate cancer cell lines and xenografts as well as patient samples of untreated, hormone‐naïve, and hormone‐refractory prostate carcinomas for sequence variations using denaturing high‐performance liquid chromatography (DHPLC), for gene copy number using fluorescence in situ hybridization (FISH), and for expression using both quantitative RT‐PCR and immunostaining. Only one sequence variation was found in all 37 cell lines and xenografts analysed. BAG‐1 gene amplification was detected in two xenografts. In addition, gene amplification was found in 6 of 81 (7.4%) hormone‐refractory clinical tumours, whereas no amplification was found in any of the 130 untreated tumours analysed. Additionally, gain of the BAG‐1 gene was observed in 27.2% of the hormone‐refractory tumours and in 18.5% of the untreated carcinomas. In a set of 263 patient samples, BAG‐1L protein expression was significantly higher in hormone‐refractory tumours than in primary tumours (p = 0.002). Altogether, these data suggest that amplification and overexpression of BAG‐1L may be involved in the progression of prostate cancer. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Associations Between G/A1229, A/G3944, T/C30875, C/T48200 and C/T65013 Genotypes and Haplotypes in the Vitamin D Receptor Gene, Ultraviolet Radiation and Susceptibility to Prostate Cancer

Ultraviolet radiation (UVR) may protect against prostate cancer via a mechanism involving vitamin D. Thus, the vitamin D receptor (VDR) gene is a susceptibility candidate, though published data are discrepant. We studied the association of prostate cancer risk with five VDR single nucleotide polymorphisms (SNPs): G/A¹²²⁹ (SNP 1), A/G³⁹⁴⁴ (SNP 2), T/C³⁰⁸⁷⁵ (SNP 3), C/T⁴⁸²⁰⁰ (SNP 4) and C/T⁶⁵⁰¹³ (SNP 5), in 430 cancer and 310 benign prostatic hypertrophy (BPH) patients. The SNP 2 GG genotype frequency was lower in cancer than BPH patients (odds ratio = 0.63, 95% CI = 0.41–0.98, p = 0.039). SNPs 1 and 2, and SNPs 4 and 5, were in linkage disequilibrium. Two copies of haplotypes comprising SNPs 1‐2, G‐G (odds ratio = 0.63, p = 0.039), SNPs 2‐3 G‐C (odds ratio = 0.45, p = 0.008) and SNPs 1‐2‐3 G‐G‐C (odds ratio = 0.44, p = 0.006), but not SNPs 1‐3, G‐C (odds ratio = 0.81, p = 0.34), were associated with reduced risk (reference, no copies of the haplotypes) . These associations were observed after stratification of subjects by extent of UVR exposure. These data show that SNP 2 GG genotype mediates prostate cancer risk, complementing studies reporting this allele is protective in malignant melanoma pathogenesis. They further suggest that published associations of risk with SNP 1 may result from linkage disequilibrium with SNP 2.     

Stromal Androgen Receptor in Prostate Development and Cancer

The androgen receptor (AR) in stromal cells contributes significantly to the development and growth of prostate during fetal stages as well as during prostate carcinogenesis and cancer progression. During prostate development, stromal AR induces and promotes epithelial cell growth, as observed from tissue recombinant and mouse knockout studies. During prostate carcinogenesis and progression, the stromal cells begin to lose AR expression as early as at the stage of high-grade prostatic intraepithelial neoplasia. The extent of loss of stromal AR is directly proportional to the degree of differentiation (Gleason grade) and progression of prostate cancer (PCa). Co-culture studies suggested that stromal AR inhibits the growth of malignant epithelial cells, possibly through expression of certain paracrine factors in the presence of androgens. This functional reversal of stromal AR, from growth promotion during fetal prostate development to mediating certain growth-inhibiting effects in cancer, explains to some extent the reason that loss of AR expression in stromal cells may be crucial for development of resistance to androgen ablation therapy for PCa. From a translational perspective, it generates the need to re-examine the current therapeutic options and opens a fundamental new direction for therapeutic interventions, especially in advanced PCa.CME Accreditation Statement: This activity (“ASIP 2014 AJP CME Program in Pathogenesis”) has been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Society for Clinical Pathology (ASCP) and the American Society for Investigative Pathology (ASIP). ASCP is accredited by the ACCME to provide continuing medical education for physicians.The ASCP designates this journal-based CME activity (“ASIP 2014 AJP CME Program in Pathogenesis”) for a maximum of 48 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.CME Disclosures: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose.Prostate cancer (PCa) is the most common non-skin malignancy in the male population within the United States and is the second most common cancer in men worldwide.¹ It is also one of the leading causes of cancer-related deaths in males in the United States.Normal human prostate is composed of an epithelial tissue and an adjacent stroma. The epithelium is composed of two principal cell types, the tall columnar secretory luminal cells that line the glandular ducts and the flattened basal cells surrounding them. In addition, some rare neuroendocrine cells are also present. Often, the terms mesenchyme and stroma are loosely used. Herein, mesenchyme refers to the mesodermal-derived fetal or newborn tissues with instructive induction potential. The word stroma describes the tissues surrounding the prostatic epithelium, later in development. In the adult human prostate, the stroma is composed mainly of smooth muscle cells. However, it also includes some fibroblasts, nerves, blood vessels, and various infiltrating immune and inflammatory cell types.Circulating androgens mediate the development and function of prostate by stimulating the androgen receptor (AR). Rat studies have shown that in stroma, AR is expressed in mesenchymal cells of the urogenital sinus (UGS), especially those adjacent to the epithelium, concurrent with the formation of prostatic buds.^2,3 As the prostate develops and the mesenchymal cells differentiate to form smooth muscle, AR expression is widespread, but not universal, throughout the muscle. In the past, investigators have mainly focused on studying epithelial AR function in prostate. Relatively limited data are available to describe the expression and function of stromal AR in prostate development^2–14 and cancer. Stromal AR is involved in both prostate development and prostate carcinogenesis, with distinct functions in these two processes. We examine the current knowledge and understanding of stromal AR function, including its translational significance.     

Androgen receptor gene mutations in 46,XY females with germ cell tumours

We present clinical findings and molecular characterization in two patients previously diagnosed as 46,XY female gonadal dysgenesis with germ cell tumour. Both patients showed a female general phenotype with unambiguously female external genitalia and primary amenorrhoea compatible with complete androgen insensitivity syndrome. The first patient, at the age of 31 years, developed a dysgerminoma measuring 8 x 13 x 10 cm in one abdominal testis. Genetic analysis revealed a single nucleotide substitution on exon 4 in the hormone-binding domain of the androgen receptor (AR) gene, resulting in a change of codon 681 GAG (glutamic acid) to AAG (lysine). The second patient, at the age of 17 years, developed a dysgerminoma measuring 12 x 10 x 7 cm in one abdominal testis and gonadoblastoma in the other testis. Genetic analysis showed a point mutation on exon 3 in the DNA-binding domain of the AR gene resulting in a change of codon 607 CGA (arginine) to CAA (glutamine). Arg607-Gln and Arg608-Lys point mutations in the DNA-binding domain of the AR gene have been associated with male breast cancer in partial androgen insensitivity syndrome. A codon 607 mutation in the DNA-binding domain of the AR gene in our patient 2 is associated with early development of germ cell tumour. We suggest regular molecular genetic analysis of the AR gene in 46,XY females with germ cell tumour and androgen insensitivity syndrome to detect differences in the specific regions of AR gene involved in early progression toward oncogenesis of the dysgenetic gonads.     

Androgen receptor amplification is associated with increased cell proliferation in prostate cancer

Mechanisms of prostate cancer progression during hormonal therapy and the pathobiologic consequences of androgen receptor (AR) gene amplification are inadequately known. To further investigate the hypothesis that AR gene amplification is associated with increased cell proliferation, we analyzed 123 paraffin-embedded prostate cancer specimens from men who experienced tumor relapse during androgen withdrawal therapy. We used fluorescence in situ hybridization to quantify AR gene copy number and Ki-67 immunohistochemistry to determine cell proliferation. One third of the tumors showed AR gene amplification. Among tumors with AR amplification, the mean cell proliferation rate was 19.8 (SD, 12.3; 95% confidence interval [CI], 15.4-24.1), whereas it was 13.0 (SD, 15.9; 95% CI, 9.1-16.8) in tumors without amplification (P = .032). In the best fitting logistic regression model, only proliferation remained significant (P = .040). When the median Ki-67 labeling index (6.7%) of all tumors was used as a cutoff point, the tumors with AR amplification were more frequently highly proliferating than tumors with no amplification (P = .010; odds ratio, 3.4; 95% CI, 1.4-8.3). Our results imply that progression of prostate cancer during androgen withdrawal therapy is associated with AR gene amplification and increased cell proliferation rate in one third of tumors. We suggest that AR gene amplification is an important molecular mechanism underlying the increase in proliferation rate of a substantial fraction of recurrent prostate carcinomas. However, efforts should be targeted to develop prostate cancer cell lines to study causal relationships between AR gene amplification and various biologic variables.