Discovery of circulating microRNAs associated with human prostate cancer using a mouse model of disease.

Circulating microRNAs (miRNAs) are emerging as useful non-invasive markers of disease. The objective of this study was to use a mouse model of prostate cancer as a tool to discover serum miRNAs that could be assessed in a clinical setting. Global miRNA profiling identified 46 miRNAs at significantly altered levels (p ≤ 0.05) in the serum of TRansgenic Adenocarcinoma of Mouse Prostate (TRAMP) mice with advanced prostate cancer compared to healthy controls. A subset of these miRNAs with known human homologues were validated in an independent cohort of mice and then measured in serum from men with metastatic castration-resistant prostate cancer (mCRPC; n = 25) or healthy men (n = 25). Four miRNAs altered in mice, mmu-miR-141, mmu-miR-298, mmu-miR-346 and mmu-miR-375, were also found to be at differential levels in the serum of men with mCRPC. Three of these (hsa-miR-141, hsa-miR-298 and hsa-miR-375) were upregulated in prostate tumors compared with normal prostate tissue, suggesting that they are released into the blood as disease progresses. Moreover, the intra-tumoral expression of hsa-miR-141 and hsa-miR-375 were predictors of biochemical relapse after surgery. This study is the first to demonstrate that specific serum miRNAs are common between human prostate cancer and a mouse model of the disease, highlighting the potential of such models for the discovery of novel biomarkers.

Prevalence and factors associated with uncomplicated storage and voiding lower urinary tract symptoms in community-dwelling Australian men.

PURPOSE: To determine the prevalence of, and associated risk factors for, voiding and storage lower urinary tract symptoms (LUTS) in a population-based sample of Australian men. METHODS: Data were collected from 1,103 men randomly selected, community-dwelling men, as part of the Florey Adelaide Male Ageing Study, after exclusion of men with prostate or bladder cancer or prior surgery to either organ. The presence of LUTS was assessed using the International Prostate Symptom Score. Urine flow was measured via flow meter. Demographic, clinical, and bio-psychosocial data were collected by questionnaire. RESULTS: The prevalence of total, storage, and voiding LUTS was 18.1, 28.0 and 12.6%, respectively. The most common storage symptoms were frequency (12.3%), nocturia (9.9%) and urgency (8.1%), and voiding symptoms were weak stream (8.5%), intermittency (5.4%), incomplete emptying (5.1%) and straining (2.4%). There were linear associations between storage LUTS and increased abdominal fat mass, plasma glucose and low HDL cholesterol (components of the metabolic syndrome), obstructive sleep apnoea (OSA) risk, and retirement. Voiding symptoms were associated with a previous diagnosis of benign prostatic enlargement (BPH), mean peak urine flow, total energy intake, elevated risk of OSA, erectile dysfunction, physician-diagnosed thyroid dysfunction and higher household income. CONCLUSIONS: The close association of storage LUTS with the metabolic syndrome, and of both storage and voiding LUTS with OSA, suggest that these conditions should be considered in men presenting with LUTS.

Prostatic chondroitin sulfate is increased in patients with metastatic disease but does not predict survival outcome.

BACKGROUND: Previous studies from our laboratory demonstrated a strong association between an elevated level of chondroitin sulfate (CS) in peritumoral stroma and PSA-relapse in patients with early stage disease. In this study we determined whether CS levels could predict overall survival in men diagnosed with advanced prostate cancer subsequently treated by orchiectomy alone. METHODS: CS was localized in archived prostatic tissues by immunohistochemistry, and the level of CS expression as measured by video image analysis was compared in cohorts of 157 and 60 men with early stage or advanced disease, respectively. RESULTS: The CS levels in the peritumoral stroma of patients without relapse after treatment for early stage disease was significantly reduced compared to levels in prostate tissue from patients who either relapsed (P = 0.003) or were diagnosed with advanced prostate cancer (P < 0.00001). There was no difference between the median CS level in the peritumoral prostatic stroma of early stage patients that relapsed after treatment and patients diagnosed with advanced prostate cancer. Increased CS levels (P < 0.0001) and high Gleason score (P < 0.0001) were associated with an increased rate of PSA-relapse in the cohort of patients with early stage disease. However, neither CS level nor Gleason score alone or in combination could predict survival outcome in patients with advanced prostate cancer following androgen deprivation therapy. CONCLUSIONS: Although peritumoral CS levels and Gleason score are strong predictors of relapse-free survival in early stage prostate cancer patients, neither peritumoral CS levels nor Gleason score can predict survival outcome in patients with advanced disease.

Control of androgen receptor signaling in prostate cancer by the cochaperone small glutamine rich tetratricopeptide repeat containing protein alpha.

Although the androgen receptor (AR) is accepted as the major determinant of prostate cancer cell survival throughout disease progression, it is currently unclear how the receptor sustains genomic signaling under conditions of systemic androgen ablation. Here, we show that the evolutionarily conserved Hsp70/Hsp90 cochaperone, small glutamine-rich tetratricopeptide repeat containing protein alpha (alphaSGT), interacts with the hinge region of the human AR in yeast and mammalian cells. Overexpression and RNA interference revealed that alphaSGT acts to (a) promote cytoplasmic compartmentalization of the AR, thereby silencing the receptors basal/ligand-independent transcriptional activity, (b) regulate the sensitivity of receptor signaling by androgens, and (c) limit the capacity of noncanonical ligands to induce AR agonist activity. Immunofluorescence, coactivator, and chromatin immunoprecipitation analyses strongly suggest that these effects of alphaSGT on AR function are mediated by interaction in the cytoplasm and are distinct from the receptors response to classic coregulators. Quantitative immunohistochemical analysis of alphaSGT and AR levels in a cohort of 32 primary and 64 metastatic human prostate cancers revealed dysregulation in the level of both proteins during disease progression. The significantly higher AR/alphaSGT ratio in metastatic samples is consistent with the sensitization of prostate tumor cells to androgen signaling with disease progression, particularly in a low-hormone environment. These findings implicate alphaSGT as a molecular rheostat of in vivo signaling competence by the AR, and provide new insight into the determinants of androgen sensitivity during prostate cancer progression.

Immunohistochemical level of unsulfated chondroitin disaccharides in the cancer stroma is an independent predictor of prostate cancer relapse.

The glycosaminoglycan chondroitin sulfate is significantly increased in the peritumoral stroma of prostate tumors compared with normal stroma and is an independent predictor of prostate-specific antigen (PSA) relapse following radical prostatectomy. In this study, we determined whether specific alterations in the sulfation pattern of glycosaminoglycan chains in clinically organ-confined prostate cancer are associated with PSA relapse. Immunoreactivity to distinct glycosaminoglycan disaccharide epitopes was assessed by manually scoring the staining intensity in prostate tissues from patients with benign prostatic hyperplasia (n = 19), early-stage cancer (cohort 1, n = 55 and cohort 2, n = 275), and advanced-stage cancer (n = 20). Alterations to glycosaminoglycans in benign and malignant prostate tissues were determined by cellulose acetate chromatography and high-pressure liquid chromatography. Glycosaminoglycan disaccharide epitopes were localized to the peritumoral stroma of clinically localized prostate cancer. The level of immunostaining for unsulfated disaccharides (C0S) in the peritumoral stroma, but not for 4-sulfated (C4S) or 6-sulfated disaccharides (C6S), was significantly associated with the rate of PSA relapse following radical prostatectomy. High levels of C0S immunostaining were determined to be an independent predictor of PSA relapse (1.6-fold, P = 0.020). Advanced-stage prostate cancer tissues exhibited reduced electrophoretic mobility for chondroitin sulfate and increased unsulfated disaccharides when compared with benign prostatic hyperplasia tissues, whereas the sulfated disaccharide levels were unaffected. The level of C0S immunostaining in the peritumoral stroma is an independent determinant of PSA failure in clinically localized prostate cancer. Specific alterations to chondroitin sulfate side chains occurring during tumor development may be a crucial step for disease progression in prostate cancer.

Modulation of prostate cancer cell attachment to matrix by versican.

In this study, we examined whether versican, a recognized anti-cell adhesive molecule for various mesenchymal and nerve cell types, influences prostate cancer cell adhesion to extracellular matrix components. Prostate cancer cell adhesion to fibronectin, a major component of the stromal extracellular matrix was inhibited by versican-rich conditioned medium (CM) from cultured human prostatic fibroblasts. In contrast, cancer cell attachment to laminin, a component of basement membranes, was not affected by the same CM. Consistent with versican being the active inhibitory factor in the CM, the integrity of chondroitin sulfate side chains and an ability to bind the RGD (Arg-Gly-Asp) peptide sequence of fibronectin were essential for the inhibition of prostate cancer cell attachment to fibronectin. Subsequent studies with versican purified from human prostate fibroblast CM confirmed its anti-adhesive activity. We conclude that versican is an important modulator of tumor cell attachment to the interstitial stromal matrix of the prostate, the latter being an essential step in cancer cell motility and local invasion of the prostatic stroma.

A comparison of propensity score-based approaches to health service evaluation: a case study of a preoperative physician-led clinic for high-risk surgical patients.

RATIONALE, AIMS AND OBJECTIVES: A physician-led clinic for the preoperative optimization and management of high-risk surgical patients was implemented in a South Australian public hospital in 2008. This study aimed to estimate the costs and effects of the clinic using a mixed retrospective and prospective observational study design. METHOD: Alternative propensity score estimation methods were applied to retrospective routinely collected administrative and clinical data, using weighted and matched cohorts. Supplementary survey-based prospective data were collected to inform the analysis of the retrospective data and reduce potential unmeasured confounding. RESULTS: Using weighted cohorts, clinic patients had a significantly longer mean length of stay and higher mean cost. With the matched cohorts, reducing the calliper width resulted in a shorter mean length of stay in the clinic group, but the costs remained significantly higher. The prospective data indicated potential unmeasured confounding in all analyses other than in the most tightly matched cohorts. CONCLUSIONS: The application of alternative propensity-based approaches to a large sample of retrospective data, supplemented with a smaller sample of prospective data, informed a pragmatic approach to reducing potential observed and unmeasured confounding in an evaluation of a physician-led preoperative clinic. The need to generate tightly matched cohorts to reduce the potential for unmeasured confounding indicates that significant uncertainty remains around the effects of the clinic. This study illustrates the value of mixed retrospective and prospective observational study designs but also underlines the need to prospectively plan for the evaluation of costs and effects alongside the implementation of significant service innovations.

Dissolved urate salts out calcium oxalate in undiluted human urine in vitro: implications for calcium oxalate stone genesis.

Hyperuricosuria has long been documented as a predisposing factor to calcium oxalate (CaOx) stone pathogenesis. However, its mechanism is still without sound scientific foundation. Previously, we showed that hyperuricosuria, simulated by the addition of dissolved sodium urate, promotes the crystallization of CaOx. In the present study, we demonstrate that the urate's effect on the crystallization is attributable to its salting out CaOx from solution. Furthermore, analysis of urines revealed that their metastable limit decreased with increases in the product of the prevailing concentrations of calcium and urate: this has implications for CaOx stone genesis. We also outline anti-salting out strategies for future research for the prevention and/or treatment of CaOx calculi.

Corepressor effect on androgen receptor activity varies with the length of the CAG encoded polyglutamine repeat and is dependent on receptor/corepressor ratio in prostate cancer cells.

The response of prostate cells to androgens reflects a combination of androgen receptor (AR) transactivation and transrepression, but how these two processes differ mechanistically and influence prostate cancer risk and disease outcome remain elusive. Given recent interest in targeting AR transrepressive processes, a better understanding of AR/corepressor interaction and responses is warranted. Here, we used transactivation and interaction assays with wild-type and mutant ARs, and deletion AR fragments, to dissect the relationship between AR and the corepressor, silencing mediator for retinoic acid and thyroid hormone receptors (SMRT). We additionally tested how these processes are influenced by AR agonist and antagonist ligands, as well as by variation in the polyglutamine tract in the AR amino terminal domain (NTD), which is encoded by a polymorphic CAG repeat in the gene. SMRT was recruited to the AR ligand binding domain by agonist ligand, and as determined by the effect of strategic mutations in activation function 2 (AF-2), requires a precise conformation of that domain. A distinct region of SMRT also mediated interaction with the AR-NTD via the transactivation unit 5 (TAU5; residues 315-538) region. The degree to which SMRT was able to repress AR increased from 17% to 56% as the AR polyglutamine repeat length was increased from 9 to 42 residues, but critically this effect could be abolished by increasing the SMRT:AR molar ratio. These data suggest that the extent to which the CAG encoded polyglutamine repeat influences AR activity represents a balance between corepressor and coactivator occupancy of the same ligand-dependent and independent AR interaction surfaces. Changes in the homeostatic relationship of AR to these molecules, including SMRT, may explain the variable penetrance of the CAG repeat and the loss of AR signaling flexibility in prostate cancer progression.

Comparative biomarker expression and RNA integrity in biospecimens derived from radical retropubic and robot-assisted laparoscopic prostatectomies.

BACKGROUND: Knowledge of preanalytic conditions that biospecimens are subjected to is critically important because novel surgical procedures, tissue sampling, handling, and storage might affect biomarker expression or invalidate tissue samples as analytes for some technologies. METHODS: We investigated differences in RNA quality, gene expression by quantitative real-time PCR, and immunoreactive protein expression of selected prostate cancer biomarkers between tissues from retropubic radical prostatectomy (RRP) and robot-assisted laparoscopic prostatectomy (RALP). Sections of tissue microarray of 23 RALP and 22 RRP samples were stained with antibodies to androgen receptor (AR) and prostate-specific antigen (PSA) as intersite controls, and 14 other candidate biomarkers of research interest to three laboratories within the Australian Prostate Cancer BioResource tissue banking network. Quantitative real-time PCR was done for AR, PSA (KLK3), KLK2, KLK4, and HIF1A on RNA extracted from five RALP and five RRP frozen tissue cores. RESULTS: No histologic differences were observed between RALP and RRP tissue. Biomarker staining grouped these samples into those with increased (PSA, CK8/18, CKHMW, KLK4), decreased (KLK2, KLK14), or no change in expression (AR, ghrelin, Ki67, PCNA, VEGF-C, PAR2, YB1, p63, versican, and chondroitin 0-sulfate) in RALP compared with RRP tissue. No difference in RNA quality or gene expression was detected between RALP and RRP tissue. CONCLUSIONS: Changes in biomarker expression between RALP and RRP tissue exist at the immunoreactive protein level, but the etiology is unclear. IMPACT: Future studies should account for changes in biomarker expression when using RALP tissues, and mixed cohorts of RALP and RRP tissue should be avoided.

Global levels of specific histone modifications and an epigenetic gene signature predict prostate cancer progression and development.

BACKGROUND: Epigenetic alterations are common in prostate cancer, yet how these modifications contribute to carcinogenesis is poorly understood. We investigated whether specific histone modifications are prognostic for prostate cancer relapse, and whether the expression of epigenetic genes is altered in prostate tumorigenesis. METHODS: Global levels of histone H3 lysine-18 acetylation (H3K18Ac) and histone H3 lysine-4 dimethylation (H3K4diMe) were assessed immunohistochemically in a prostate cancer cohort of 279 cases. Epigenetic gene expression was investigated in silico by analysis of microarray data from 23 primary prostate cancers (8 with biochemical recurrence and 15 without) and 7 metastatic lesions. RESULTS: H3K18Ac and H3K4diMe are independent predictors of relapse-free survival, with high global levels associated with a 1.71-fold (P < 0.0001) and 1.80-fold (P = 0.006) increased risk of tumor recurrence, respectively. High levels of both histone modifications were associated with a 3-fold increased risk of relapse (P < 0.0001). Epigenetic gene expression profiling identified a candidate gene signature (DNMT3A, MBD4, MLL2, MLL3, NSD1, and SRCAP), which significantly discriminated nonmalignant from prostate tumor tissue (P = 0.0063) in an independent cohort. CONCLUSIONS: This study has established the importance of histone modifications in predicting prostate cancer relapse and has identified an epigenetic gene signature associated with prostate tumorigenesis. IMPACT: Our findings suggest that targeting the epigenetic enzymes specifically involved in a particular solid tumor may be a more effective approach. Moreover, testing for aberrant expression of epigenetic genes such as those identified in this study may be beneficial in predicting individual patient response to epigenetic therapies.

A novel androgen receptor amino terminal region reveals two classes of amino/carboxyl interaction-deficient variants with divergent capacity to activate responsive sites in chromatin.

The androgen receptor (AR) is an important signaling molecule in multiple tissues, yet its mode of action and cell-specific activities remain enigmatic. AR function has been best studied in the prostate, in which it is essential for growth and homeostasis of the normal organ as well as each stage of cancer development. Investigation of mechanisms responsible for continued AR action that evolve during prostate cancer progression or after hormonal management of the disease have been instructive in defining AR signaling pathways. In the current paper, we use sequence similarity and the collocation of somatic mutations in prostate cancer to define residues 501-535 of the AR amino-terminal domain as an important mediator of receptor function. Specifically, the 501-535 region is required for optimal interaction of the amino-terminal domain with both the p160 coactivator, nuclear receptor coactivator-2, and the AR-ligand binding domain in the amino/carboxyl (N/C) interaction. The N/C interaction is decreased by deletion of the 501-535 region but is distinct from deletion of the (23)FQNLF(27) peptide in that it does not affect the capacity of the AR to activate transcription from a chromatin integrated reporter or recruitment of the receptor to androgen-responsive loci in vivo. Collectively, we have been able to outline two classes of N/C-deficient AR variant that are divergent in their capacity to act in a chromatin context, thereby further defining the interplay between N/C interaction and coregulator recruitment via multiple receptor domains. These mechanisms are likely to be key determinants of the cell and promoter specific activities of the AR.

Prostate cancer and prostate-specific antigen testing in New South Wales.

OBJECTIVE: To describe trends in prostate-specific antigen (PSA) testing, prostate cancer incidence and mortality in New South Wales. DESIGN AND SETTING: Descriptive analysis using routinely collected data of observed trends in PSA testing from 1989 to 2006, and prostate cancer cases and deaths from 1972 to 2005 in NSW. MAIN OUTCOME MEASURES: Age-standardised and age-specific rates and joinpoint regression to identify changes in trends; projected trends observed before the introduction of PSA testing to quantify its impact on incidence and mortality rates. RESULTS: The number of PSA tests per year more than doubled between 1994 and 2006. Age-standardised incidence of prostate cancer peaked in 1994, fell by 10.0% per year to 1998 and then increased by 4.9% per year from 2001 to 2005. An estimated 19 602 (43%) more men than expected from preceding trends were diagnosed with prostate cancer between 1989 and 2005 after PSA testing was introduced. The incidence of recorded advanced prostate cancer at diagnosis fell from 13.0 per 100,000 men in 1987-1991 to 7.0 per 100,000 men in 2002-2005. The age-standardised mortality from prostate cancer increased by 3.6% per year between 1984 and 1990 and then fell by 2.0% per year to 2005. CONCLUSIONS: There was a sustained increase in prostate cancer incidence in NSW after PSA testing was introduced. While falls in the incidence of advanced disease at diagnosis and mortality from prostate cancer after 1993 are consistent with a benefit from PSA testing, other explanations cannot be excluded.

Elevated levels of HER-2/neu and androgen receptor in clinically localized prostate cancer identifies metastatic potential.

BACKGROUND: In this study, we investigated the expression of HER-2/neu and AR in clinically organ-confined prostate cancer to determine whether alterations in these signaling pathways contribute to the development of metastatic disease. METHODS: HER-2/neu and AR immunoreactivity were evaluated in archived prostatic tissues obtained from 53 men with clinically organ-confined disease who underwent radical prostatectomy. Associations between AR and HER-2/neu immunostaining and disease outcome were determined. RESULTS: Seventy percent (37/53) of tumors exhibited high levels of HER-2/neu immunostaining and 68% (36/53) of tumors had elevated AR levels. Patients with high levels of both HER-2/neu and AR had the highest rate of PSA failure (56%, 15/27) compared with no PSA failures amongst seven patients with low levels of both HER-2/neu and AR (log rank statistic 7.69, P = 0.021). Concurrent high levels of HER-2/neu and AR expression were significantly associated with high pathological stage (P = 0.027) and development of metastatic disease (P = 0.022). CONCLUSIONS: These findings support the notion that both the HER-2/neu and AR signaling pathways may contribute to development of metastatic disease. The subset of prostate tumors with increased HER-2/neu and AR levels may benefit from treatment strategies that target both signaling pathways.

Formation of hyaluronan- and versican-rich pericellular matrix by prostate cancer cells promotes cell motility.

Previous studies have demonstrated that high levels of hyaluronan (HA) and the chondroitin sulfate proteoglycan, versican in the peritumoral stroma are associated with metastatic spread of clinical prostate cancer. In vitro integration of HA and versican into a pericellular sheath is a prerequisite for proliferation and migration of vascular smooth muscle cells. In this study, a particle exclusion assay was used to determine whether human prostate cancer cell lines are capable of assembling a pericellular sheath following treatment with versican-containing medium and whether formation of a pericellular sheath modulated cell motility. PC3 and DU145, but not LNCaP cells formed prominent polarized pericellular sheaths following treatment with prostate fibroblast-conditioned medium. The capacity to assemble a pericellular sheath correlated with the ability to express membranous HA receptor, CD44. HA and versican histochemical staining were observed surrounding PC3 and DU145 cells following treatment with prostatic fibroblast-conditioned medium. The dependence on HA for integrity of the pericellular sheath was demonstrated by its removal following treatment with hyaluronidase. Purified versican or conditioned medium from Chinese hamster ovary K1 cells overexpressing versican V1, but not conditioned medium from parental cells, promoted pericellular sheath formation and motility of PC3 cells. Using time lapse microscopy, motile PC3 cells treated with versican but not non-motile cells exhibited a polar pericellular sheath. Polar pericellular sheath was particularly evident at the trailing edge but was excluded from the leading edge of PC3 cells. These studies indicate that prostate cancer cells recruit stromal components to remodel their pericellular environment and promote their motility.

Changes in steroid receptors and proteoglycan expression in the guinea pig prostate stroma during puberty and hormone manipulation.

BACKGROUND: Proteoglycans are structural and informational molecules important during embryogenesis and organ maturation. Maturation of the prostate is influenced by androgens and estrogens, but changes in the relative spatiotemporal expression of steroid receptors and proteoglycans during hormonal change are unexplored. METHODS: Guinea pig prostate was used to define hormone-induced changes in the expression of androgen (AR) and estrogen (ER(alpha)) receptors, chondroitin sulfate (CS) glycosaminoglycan and core proteins of versican and syndecan-1. Tissue locations of AR, ER(alpha), CS and the proteoglycans versican and syndecan-1 were determined by immunohistochemistry. Cellular content of ER(alpha) and syndecan-1 was assessed visually. Versican, CS56 epitope, and AR were quantified by image analysis. RESULTS: AR expression within prostate epithelial and stromal cell nuclei decreased following castration and increased following treatment of castrate animals with dihydrotestosterone (DHT). ER(alpha) expression was restricted to prostate stromal cell nuclei and decreased during puberty, and following treatment of castrate animals with DHT. Versican was present in periacinar stroma immediately peripheral to basal epithelial cells, fibromuscular stromal tissue bands surrounding acinar units, and loose fibrovascular connective tissue interspersed between individual acini. Versican and native CS expression decreased (>10-fold) in periacinar stroma during puberty and following administration of DHT to castrated animals. Expression of syndecan-1 was restricted to fibromuscular cells of prostate stroma, and remained constant during puberty and hormone manipulation. CONCLUSIONS: ER(alpha), versican core protein and CS side chain epitopes are negatively regulated in prostate stromal tissue by DHT, whilst AR levels are positively regulated.

Androgen receptor levels in prostate cancer epithelial and peritumoral stromal cells identify non-organ confined disease.

BACKGROUND: Although up to 30% of men who undergo radical prostatectomy for clinically organ-confined prostate cancer will relapse with disseminated disease, currently it is not possible to predict these patients. METHODS: Androgen receptor (AR) immunoreactivity in stromal and epithelial compartments of tumor foci was evaluated by video image analysis in 53 radical prostatectomy specimens. Kaplan-Meier and Cox Regression analyses were used to determine whether AR immunostaining was related to rate and risk of relapse, respectively. RESULTS: Ninety-eight percent (52/53) of the tumors contained AR positive malignant epithelial cells. Kaplan-Meier analysis indicated that patients with high AR levels (>64% AR positive nuclear area) in the malignant epithelial cells or low AR levels (