COUP-TFII inhibits TGF-ß-induced growth barrier to promote prostate tumorigenesis.

Mutations in phosphatase and tensin homologue (PTEN) or genomic alterations in the phosphatidylinositol-3-OH kinase-signalling pathway are the most common genetic alterations reported in human prostate cancer. However, the precise mechanism underlying how indolent tumours with PTEN alterations acquire metastatic potential remains poorly understood. Recent studies suggest that upregulation of transforming growth factor (TGF)-ß signalling triggered by PTEN loss will form a growth barrier as a defence mechanism to constrain prostate cancer progression, underscoring that TGF-ß signalling might represent a pre-invasive checkpoint to prevent PTEN-mediated prostate tumorigenesis. Here we show that COUP transcription factor II (COUP-TFII, also known as NR2F2), a member of the nuclear receptor superfamily, serves as a key regulator to inhibit SMAD4-dependent transcription, and consequently overrides the TGF-ß-dependent checkpoint for PTEN-null indolent tumours. Overexpression of COUP-TFII in the mouse prostate epithelium cooperates with PTEN deletion to augment malignant progression and produce an aggressive metastasis-prone tumour. The functional counteraction between COUP-TFII and SMAD4 is reinforced by genetically engineered mouse models in which conditional loss of SMAD4 diminishes the inhibitory effects elicited by COUP-TFII ablation. The biological significance of COUP-TFII in prostate carcinogenesis is substantiated by patient sample analysis, in which COUP-TFII expression or activity is tightly correlated with tumour recurrence and disease progression, whereas it is inversely associated with TGF-ß signalling. These findings reveal that the destruction of the TGF-ß-dependent barrier by COUP-TFII is crucial for the progression of PTEN-mutant prostate cancer into a life-threatening disease, and supports COUP-TFII as a potential drug target for the intervention of metastatic human prostate cancer.

Influence of the neural microenvironment on prostate cancer.

BACKGROUND: Nerves are key factors in prostate cancer (PCa), but the functional role of innervation in prostate cancer is poorly understood. PCa induced neurogenesis and perineural invasion (PNI), are associated with aggressive disease. METHOD: We denervated rodent prostates chemically and physically, before orthotopically implanting cancer cells. We also performed a human neoadjuvant clinical trial using botulinum toxin type A (Botox) and saline in the same patient, before prostatectomy. RESULT: Bilateral denervation resulted in reduced tumor incidence and size in mice. Botox treatment in humans resulted in increased apoptosis of cancer cells in the Botox treated side. A similar denervation gene array profile was identified in tumors arising in denervated rodent prostates, in spinal cord injury patients and in the Botox treated side of patients. Denervation induced exhibited a signature gene profile, indicating translation and bioenergetic shutdown. Nerves also regulate basic cellular functions of non-neoplastic epithelial cells. CONCLUSION: Nerves play a role in the homeostasis of normal epithelial tissues and are involved in prostate cancer tumor survival. This study confirms that interactions between human cancer and nerves are essential to disease progression. This work may make a major impact in general cancer treatment strategies, as nerve/cancer interactions are likely important in other cancers as well. Targeting the neural microenvironment may represent a therapeutic approach for the treatment of human prostate cancer.

Obesity modulates diaphragm curvature in subjects with and without COPD.

Obesity is a common comorbidity of chronic obstructive pulmonary disease (COPD) and has been associated with worse outcomes. However, it is unknown whether the interaction between obesity and COPD modulates diaphragm shape and consequently its function. The body mass index (BMI) has been used as a correlate of obesity. We tested the hypothesis that the shape of the diaphragm muscle and size of the ring of its insertion in non-COPD and COPD subjects are modulated by BMI. We recruited 48 COPD patients with postbronchiodilator forced expiratory volume in 1 s (FEV1)-to-forced vital capacity (FVC) < 0.7 and 29 age-matched smoker/exsmoker control (non-COPD) subjects, who underwent chest computed tomography (CT) at lung volumes ranging from functional residual capacity (FRC) to total lung capacity (TLC). We then computed maximum principal diaphragm curvature in the midcostal region of the left hemidiaphragm at the end of inspiration during quiet breathing (EI) and at TLC. The radius of maximum curvature of diaphragm muscle increased with BMI in both COPD and non-COPD subjects. The size of diaphragm ring of insertion on the chest wall also increased significantly with increasing BMI. Surprisingly, COPD severity did not appear to cause significant alteration in diaphragm shape except in normal-weight subjects at TLC. Our data uncovered important factors such as BMI, the size of the diaphragm ring of insertion, and disease severity that modulate the structure of the ventilatory pump in non-COPD and COPD subjects.

GATA2 facilitates steroid receptor coactivator recruitment to the androgen receptor complex.

The androgen receptor (AR) is a key driver of prostate cancer (PC), even in the state of castration-resistant PC (CRPC) and frequently even after treatment with second-line hormonal therapies such as abiraterone and enzalutamide. The persistence of AR activity via both ligand-dependent and ligand-independent mechanisms (including constitutively active AR splice variants) highlights the unmet need for alternative approaches to block AR signaling in CRPC. We investigated the transcription factor GATA-binding protein 2 (GATA2) as a regulator of AR signaling and an actionable therapeutic target in PC. We demonstrate that GATA2 directly promotes expression of both full-length and splice-variant AR, resulting in a strong positive correlation between GATA2 and AR expression in both PC cell lines and patient specimens. Conversely, GATA2 expression is repressed by androgen and AR, suggesting a negative feedback regulatory loop that, upon androgen deprivation, derepresses GATA2 to contribute to AR overexpression in CRPC. Simultaneously, GATA2 is necessary for optimal transcriptional activity of both full-length and splice-variant AR. GATA2 colocalizes with AR and Forkhead box protein A1 on chromatin to enhance recruitment of steroid receptor coactivators and formation of the transcriptional holocomplex. In agreement with these important functions, high GATA2 expression and transcriptional activity predicted worse clinical outcome in PC patients. A GATA2 small molecule inhibitor suppressed the expression and transcriptional function of both full-length and splice-variant AR and exerted potent anticancer activity against PC cell lines. We propose pharmacological inhibition of GATA2 as a first-in-field approach to target AR expression and function and improve outcomes in CRPC.

The Germ Cell Gene TDRD1 as an ERG Target Gene and a Novel Prostate Cancer Biomarker.

BACKGROUND: TMPRSS2-ERG fusion occurs in about half of prostate cancers and results in over-expression of the oncogenic ERG protein in the prostate. The mechanism by which ERG contributes to prostate cancer initiation and progression remains largely unknown. Because ERG is a transcriptional activator, we reasoned that the target genes regulated by ERG could contribute to prostate cancer development. METHODS: In a search for ERG target genes, we took advantage of published datasets from the MSKCC Prostate Oncogene Project, in which a comprehensive analysis was applied to define transcriptomes in 150 prostate tumors. We retrieved the mRNA expression dataset, split them based on ERG expression, and identified genes whose expression levels are associated with ERG mRNA levels. RESULTS: mRNA expression levels of 21 genes were found to be significantly increased, while for one gene it was decreased in ERG-positive prostate tumors. Among them, the expression of TDRD1 was the most significantly increased in ERG-positive tumors. Among 131 primary prostate tumors which were primarily from European American patients, TDRD1 is over-expressed in 68% of samples, while ERG is overexpressed in 48% of samples, suggesting an additional ERG-independent mechanism of TDRD1 overexpression. In African American prostate tumors, TDRD1 mRNA is expressed in 44%, while ERG is expressed in 24% of samples. In normal tissues, TDRD1 mRNA is exclusively expressed in germ cells and its protein is also known as cancer/testis antigen 41.1 (CT41.1). We generated a mouse monoclonal antibody that recognizes human TDRD1 protein with high specificity and sensitivity. By Western blot analysis and immunohistochemistry (IHC) staining, we demonstrate that TDRD1 protein is expressed in the majority of human prostate tumors, but not in normal prostate tissue. Finally, TDRD1 is not induced in the prostate of ERG overexpression transgenic mice, suggesting that such model does not fully recapitulate the TMPRSS2/ERG fusion-dependent human prostate cancer development. CONCLUSIONS: Our results suggest TDRD1 as a novel prostate cancer biomarker. As an ERG target gene, TDRD1 might play an important role in human prostate cancer development, and as a cancer/testis antigen, TDRD1 might have long-term potential to be a therapeutic target for prostate cancer immunotherapy. Prostate 76:1271-1284, 2016. © 2016 Wiley Periodicals, Inc.

Loss of caveolin-1 in prostate cancer stroma correlates with reduced relapse-free survival and is functionally relevant to tumour progression.

Levels of caveolin-1 (Cav-1) in tumour epithelial cells increase during prostate cancer progression. Conversely, Cav-1 expression in the stroma can decline in advanced and metastatic prostate cancer. In a large cohort of 724 prostate cancers, we observed significantly decreased levels of stromal Cav-1 in concordance with increased Gleason score (p = 0.012). Importantly, reduced expression of Cav-1 in the stroma correlated with reduced relapse-free survival (p = 0.009), suggesting a role for stromal Cav-1 in inhibiting advanced disease. Silencing of Cav-1 by shRNA in WPMY-1 prostate fibroblasts resulted in up-regulation of Akt phosphorylation, and significantly altered expression of genes involved in angiogenesis, invasion, and metastasis, including a > 2.5-fold increase in TGF-ß1 and γ-synuclein (SNCG) gene expression. Moreover, silencing of Cav-1 induced migration of prostate cancer cells when stromal cells were used as attractants. Pharmacological inhibition of Akt caused down-regulation of TGF-ß1 and SNCG, suggesting that loss of Cav-1 in the stroma can influence Akt-mediated signalling in the tumour microenvironment. Cav-1-depleted stromal cells exhibited increased levels of intracellular cholesterol, a precursor for androgen biosynthesis, steroidogenic enzymes, and testosterone. These findings suggest that loss of Cav-1 in the tumour microenvironment contributes to the metastatic behaviour of tumour cells by a mechanism that involves up-regulation of TGF-ß1 and SNCG through Akt activation. They also suggest that intracrine production of androgens, a process relevant to castration resistance, may occur in the stroma.

Determining prostate cancer-specific death through quantification of stromogenic carcinoma area in prostatectomy specimens.

We previously reported that reactive stroma grading in prostate cancer (PCa) is predictive of biochemical recurrence in prostatectomies and biopsies. In this study, we tested whether quantifying the percentage of reactive stromal grade 3 (RSG 3; stromogenic carcinoma pattern) in the entire tumor is predictive of PCa-specific death. Whole-mount prostatectomies operated by a single surgeon obtained between 1983 and 1998 were reviewed. Reactive stroma was evaluated as described previously, and areas of RSG 3 in the entire tumor were registered as percentages of total tumor. Statistical analysis was performed using Spearman, Kaplan-Meier, and Cox analyses. In all, 872 cases were evaluable. Quantification of RSG 3 percentage was an independent predictor of biochemical recurrence, analyzed as a continuous or grouped variable. Patients with higher RSG 3 percentages (larger tumor areas with RSG 3) had a significantly decreased biochemical recurrence-free survival than those with a lower RSG 3 percentage, even within the Gleason score 7 subset of patients. A nomogram introduced this new variable to the model. Furthermore, quantification of RSG 3 percentage was significantly predictive of PCa-specific death. Quantification of the RSG 3 (stromogenic carcinoma) area in PCa provides additional novel information on prognosis. These data substantiate the concept that the tumor microenvironment holds significant predictive information, as well as biological significance.

Prognostic value of Akt-1 in human prostate cancer: a computerized quantitative assessment with quantum dot technology.

BACKGROUND: Akt/protein kinase B signaling pathway has been implicated in tumorigenesis and progression. Previous studies showed the predictive potential of p-Akt-1, but total Akt-1 could provide more reliable information. We used image deconvolution, nanotechnology (quantum dots), and image analysis to improve Akt-1 quantification. DESIGN: This tissue microarray study included 840 radical prostatectomy cases. Slides were incubated with primary antibody against nonphosphorylated Akt-1 (Akt-1) followed by biotinylated secondary antibody and then by Qdot655 streptavidin conjugate. Slides were imaged under fluorescence microscopy and spectral deconvolution (Nuance) and quantified using plug-in image analysis software. Average intensity of Akt-1 signal was measured and subject to statistical analysis. Multivariate analysis (Cox regression) was applied to assess the prognostic value of Akt-1 for biochemical recurrence and prostate cancer-specific death. Akt-1 expression was also examined for correlations with Ki-67 index and apoptotic index in our database. RESULT: Akt-1 was inversely correlated with apoptotic index (rho = -0.203; P = 0.004) but not with Ki-67 index. The correlation between Akt and p-Akt is significant but weak (P = 0.0496; R(2) = 0.118). On multivariate analysis Akt-1 was independently predictive of biochemical recurrence [hazard ratio, 2.863 (95% confidence interval, 1.127-7.271); P = 0.0270]. Akt-1 level is also predictive of prostate cancer-specific death (P = 0.0376). CONCLUSION: High levels of Akt-1, assessed by quantum dots, deconvolution imaging, and image analysis, are associated with a higher risk of biochemical recurrence and prostate cancer-specific death.

Cytoplasmic accumulation of glycogen synthase kinase-3beta is associated with aggressive clinicopathological features in human prostate cancer.

BACKGROUND: Activation of glycogen synthase kinase-3 (GSK-3) is involved in the regulation of cell growth, differentiation, mobility, proliferation and survival. However, its clinicopathologic significance remains unclear in prostate cancer (PCa). MATERIALS AND METHODS: A tissue microarray was produced from 640 samples. Sections were immunostained with an antibody against the non-phosphorylated form of GSK-3(GSK-3beta) and were digitized. Spearman correlation test was processed for correlations between GSK-3beta and biological and clinicopathological variables. The prognostic value of GSK-3beta was analyzed by Cox Regression model. RESULTS: Cytoplasmic GSK-3beta was higher in PCa than in normal prostate (mean expression index 4.55 vs. 3.50, p<0.0001). Conversely, nuclear expression was higher in normal prostate than that in PCa (3.38 vs. 2.04, p<0.0001). Cytoplasmic levels of GSK-3beta were correlated with clinical stage (rho=0.095, p=0.0337), lymph node metastasis (rho=0.116, p=0.0096), extracapsular extension (rho=0.092, p=0.0392), and Gleason score (rho=0.167, p=0.0002). Increased cytoplasmic GSK-3beta expression was correlated with high Ki-67 labeling index (rho=0.319, p<0.0001), low apoptotic index by TUNEL (rho=-0.118, p=0.0134), high levels of androgen receptor (rho=0.292, p<0.0001) and p-Akt (rho=0.396, p<0.0001). Patients with higher cytoplasmic levels of GSK-3beta had a two-fold risk of biochemical recurrence-free survival compared to those with lower levels of GSK-3beta [HR 1.934 (1.020-3.667), p=0.043]. CONCLUSION: Cytoplasmic accumulation of GSK-3beta is potentially associated with a pro-survival mechanism that promotes PCa development and progression.

Bortezomib-mediated inhibition of steroid receptor coactivator-3 degradation leads to activated Akt.

PURPOSE: To assess the safety of administering bortezomib to patients undergoing a radical prostatectomy, to assess pathologic changes induced by bortezomib in prostate cancer specimen, and to verify alterations by the drug in proteasome protein targets. EXPERIMENTAL DESIGN: Bortezomib is a proteasome inhibitor that has shown activity in vitro and in vivo in prostate cancer. We performed a neoadjuvant clinical trial of bortezomib in men with prostate cancer at high risk of recurrence. The primary endpoints were to evaluate safety and biological activity. RESULTS: Bortezomib is generally safe in the preoperative setting. Antitumor activity was manifested by tumor cytopathic effect, drops in serum prostate-specific antigen in some patients, and increases in tumor apoptosis. This was associated with cytoplasmic entrapment of nuclear factor-kappaB. We found an unexpected increase in proliferation in treated tissues and in vitro. Bortezomib also increased SRC-3 levels and phosphorylated Akt, both in vitro and in treated prostate cancer tissues. Knockdown of SRC-3 blocked the increase in activated Akt in vitro. Combined treatment with bortezomib and the Akt inhibitor perifosine was more effective than either agent alone in vitro. CONCLUSION: These data suggest that combined therapies targeting the proteasome and the Akt pathway may have increased efficacy.

Targeting Aurora kinases for the treatment of prostate cancer.

Inappropriate expression of the Aurora kinases can induce aberrant mitosis, centrosome irregularities, and chromosomal instability, which lead to anueploidy and cell transformation. Here, we report that Aurora-A and Aurora-B are highly expressed in primary human and mouse prostate cancers and prostate cancer cell lines. In clinical samples, levels of Aurora-A and Aurora-B were significantly elevated in prostatic intraepithelial neoplasia lesions and prostate tumors when compared with the non-neoplastic samples. Interestingly, expression of Aurora-A in non-neoplastic prostates correlated with seminal vesicle invasion (rho = 0.275, P = 0.0169) and in prostate tumor with positive surgical margins (rho = 0.265, P = 0.0161). In addition, nuclear expression of Aurora-B in prostatic intraepithelial neoplasia lesions correlated with clinical staging of the tumor (rho = -0.4, P = 0.0474) whereas cytoplasmic expression in tumors correlated with seminal vesicle invasion (rho = 0.282, P = 0.0098). Cell lines and primary tumors derived from the TRAMP model were also found to express high levels of Aurora-A and Aurora-B. When human PC3, LNCaP, and mouse C1A cells were treated with the potent Aurora kinase inhibitor VX680, which attenuates phosphorylation of histone H3, cancer cell survival was reduced. VX680 could further reduce cell viability >2-fold when used in combination with the chemotherapy drug doxorubicin. Our findings support a functional relationship between Aurora kinase expression and prostate cancer and the application of small-molecule inhibitors in therapeutic modalities.

Androgens modulate expression of transcription intermediary factor 2, an androgen receptor coactivator whose expression level correlates with early biochemical recurrence in prostate cancer.

Prostate cancer is an androgen-dependent disease; metastatic prostate cancer is typically treated by androgen receptor (AR) blockade. Recurrence after androgen ablation and evidence that AR continues to play a role in many prostate cancers has led to an examination of other factors that potentiate AR activity. AR is a ligand-activated transcription factor whose activity is regulated not only by hormone but also by the levels of coactivators recruited by AR to facilitate transcription. We sought to assess the consequences of reducing expression of the transcription intermediary factor 2 (TIF2) coactivator on prostate cancer cell growth and AR action in cell lines to examine TIF2 expression in prostate cancer and to correlate expression with clinical outcome. Depletion of TIF2 reduced expression of AR-induced target genes and slowed proliferation of AR-dependent and AR-independent prostate cancer cells. Remarkably, we found that TIF2 expression is directly repressed by high levels of androgens in multiple AR-expressing cell lines. Expression of a reporter containing 5'-flanking region of the TIF2 was repressed both by androgens and by the antagonist, Casodex. Expression of TIF2 correlates with biochemical (prostate-specific antigen) recurrence (P = 0.0136). In agreement with our in vitro findings, the highest expression of TIF2 was found in patients whose cancer relapsed after androgen ablation therapy, supporting the idea that AR blockade might activate pathways that lead to stimulation of AR-dependent and AR-independent proliferation of prostate epithelium. The elevated expression of TIF2 at low hormone levels likely aids in inducing AR activity under these conditions; treatment with Casodex has the potential to counteract this induction.

Stromal antiapoptotic paracrine loop in perineural invasion of prostatic carcinoma.

Caveolin-1 (cav-1) is a major scaffolding component of cell membrane invaginations (caveolae). It is involved in sequestering numerous effectors and signaling molecules and has antiapototic activities in prostate cancer. Perineural invasion (PNI) is associated with decreased apoptosis of cancer cells both in human tissues and the in vitro PNI model. We show here that stromal (perineurium) production of cav-1 is involved in a paracrine antiapoptotic loop in PNI. Transforming growth factor-beta1 is up-regulated in the cancer cells as they approach the nerve and is thought to up-regulate cav-1 in the perineurium of nerves with prostate cancer. Cav-1 is then secreted into the microenvironment and used by prostate cancer cells to inhibit apoptosis. In the in vitro PNI model, this phenomenon is partially reversed by neutralizing cav-1 antibodies or using ganglia from cav-1 knockout mice. Our results show a novel paracrine mechanism used by the prostate cancer in PNI to increase their proliferative activity and decrease apoptosis.

Correlative evidence that prostate cancer cell-derived caveolin-1 mediates angiogenesis.

Up-regulation of caveolin-1 (cav-1) has been implicated in human prostate cancer progression/metastasis and shown to promote cancer cell survival. It has also been shown that cav-1 is secreted by tumor cells and may regulate the growth, functional activities, and migration of vascular endothelial cells. However, the relationship of cav-1 expression in prostate cancer cells and tumor associated endothelial cells (TAEC) to tumor-associated angiogenesis remains to be investigated. Dual immunofluorescent labeling with antibodies to CD34 and cav-1 was performed on 56 prostate cancer specimens obtained by radical prostatectomy and stratified according to cav-1 positivity in cancer cells. The tumor microvessel densities (MVD) and cav-1 expression in TAEC within these specimens were measured and correlated with cav-1 expression in prostate cancer cells. The MVD values were significantly higher in cav-1-positive (n = 25) than in the cav-1-negative (n = 31) tumors (median of 44 versus 25 vessels/field, P = .0140). Additional studies showed that the cav-1 positivity in microvessels within tumor specimens was significantly less frequent than in the blood vessels of benign prostatic tissues (94.4% versus 98.6%, P = .0012). In contrast, the percentage of cav-1-positive TAEC in cav-1-positive tumors was significantly higher than in cav-1-negative tumors (95.8% versus 92.7%, P = .0024). This increased cav-1 positivity in TAEC was predominantly confined to regions with cav-1-positive tumor cells corresponding to the higher percentage of cav-1-positive microvessels within these regions in cav-1-positive, as opposed to cav-1-negative tumors (P = .0086). These positive correlations provide new evidence for the involvement of prostate cancer cell derived cav-1 in mediating angiogenesis during prostate cancer progression. They also establish a conceptual framework for further investigation of cav-1 proangiogenic activities.

Forkhead protein FKHR and its phosphorylated form p-FKHR in human prostate cancer.

In vitro studies suggest that the proapoptotic function of forkhead protein FKHR is probably inactivated by means of phosphorylation through the protein kinase B pathway. However, the clinical significance of FKHR in prostate cancer remains unclear. Six hundred forty radical prostatectomies were used for building tissue microarrays. Slides were stained with antibodies against FKHR and phosphorylated FKHR (p-FKHR). Correlations with clinicopathologic parameters were analyzed by Spearman rank test. Cox regression test and Kaplan-Meier test were used to determine the probability of disease recurrence, which is defined as a serum prostate-specific antigen (PSA) level greater than 0.4 ng/mL after radical prostatectomy. Nuclear FKHR level was higher in normal prostate than in benign prostatic hyperplasia and prostate cancer (P = .0000). Nuclear expression of FKHR was correlated with preoperative PSA level (rho = 0.108, P = .029), extracapsular extension (rho = 0.137, P = .005), and seminal vesicle invasion (rho = 0.101, P = .039). FKHR expression was not a significant indicator of biochemical failure by either univariate or multivariate analysis. Nuclear p-FKHR expression correlated with patients' age (rho = 0.179, P = .0003), Gleason score (rho = 0.130, P = .0083), extracapsular extension (rho = 0.227, P = .0000), clinical stage (Union Internationale Contre le Cancer system) (rho = 0.166, P = .0007), and lymph node status (rho = 0.101, P = .0401). Cytoplasmic p-FKHR correlated with patients' age (rho = 0.146, P = .0030) and clinical stage (rho = 0.117, P = .0180). Cytoplasmic p-FKHR was a significant indicator of biochemical recurrence (P = .0164; hazard ratio, 1.114-2.929). Nuclear p-FKHR strongly correlated with phosphorylated protein kinase B (rho = 0.368, P = .0000), androgen receptor (rho = 0.385, P = .0000), and Skp-2 (rho = 0.170, P = .0036). Our data suggest that the proapoptotic role of FKHR is probably regulated by several signaling pathways in prostate cancer.

Preoperative serum caveolin-1 as a prognostic marker for recurrence in a radical prostatectomy cohort.

PURPOSE: Up-regulation of caveolin-1 (cav-1) is associated with virulent prostate cancer, and serum cav-1 levels are elevated in prostate cancer patients but not in benign prostatic hyperplasia. In this study, we evaluated the potential of high preoperative serum cav-1 levels to predict biochemical progression of prostate cancer. The value of the combined preoperative markers, prostate-specific antigen (PSA), biopsy Gleason score, and serum cav-1 for predicting biochemical recurrence was also investigated. EXPERIMENTAL DESIGN: Serum samples taken from 419 prostate cancer patients before radical prostatectomy were selected from our Specialized Programs of Research Excellence prostate cancer serum and tissue bank. Serum samples were obtained 0 to 180 days before surgery and all patients had complete data on age, sex, race, stage at enrollment, and follow-up for biochemical recurrence. Serum cav-1 levels were measured according to our previously reported ELISA protocol. RESULTS: Cav-1 levels were measured in the sera of 419 prostate cancer patients; the mean serum level was 4.52 ng/mL (median 1.01 ng/mL). Patients with high serum cav-1 levels had a 2.7-fold (P = 0.0493) greater risk of developing biochemical recurrence compared with those with low serum cav-1 levels. Importantly, patients with serum PSA >/= 10 ng/mL and elevated levels of serum cav-1 had 2.44 times higher risk (P = 0.0256) of developing biochemical recurrence compared with patients with low levels of cav-1. In addition, high serum cav-1 levels combined with increasing biopsy Gleason score predicted much shorter recurrence-free survival in the group of patients with PSA >/= 10 ng/mL (P = 0.0353). Cav-1 was also able to distinguish between high- and low- risk patients with biopsy Gleason score of seven, after adjusting, for patients PSA levels (P = 0.0429). CONCLUSIONS: Overall, elevated preoperative levels of serum cav-1 predict decreased time to cancer recurrence. In the subset of patients with serum PSA of >/=10 ng/mL, the combination of serum cav-1 and biopsy Gleason score has the capacity to predict time to biochemical recurrence.

Role of SRC-1 in the promotion of prostate cancer cell growth and tumor progression.

Prostate cancer is initially androgen dependent and there is evidence that androgen receptor continues to play a role in androgen-independent prostate cancer. Androgen receptor activity depends both on the level of androgens and on the level of coactivators that interact with androgen receptor. Our goal was to evaluate the role of the androgen receptor coactivator SRC-1 in prostate cancer progression. Using tissue arrays to measure SRC-1 protein levels, we found that increased SRC-1 expression in clinically localized, androgen-dependent cancer is associated with clinical and pathologic variables of increased tumor aggressiveness. Interestingly, there was variable expression of SRC-1 in normal prostate tissue which correlated with the staining intensity of the corresponding cancer tissue. To test the contribution of SRC-1, we examined its role in androgen-dependent LNCaP and androgen-independent C4-2 prostate cancer cell lines. Using small interfering RNA to reduce expression of androgen receptor, we found that androgen receptor was required both for cell growth and for basal expression of prostate-specific antigen in the androgen-independent C4-2 cell line. Thus, although the cells can grow in an androgen-depleted medium, they remained androgen receptor dependent. Reduction of SRC-1 expression significantly reduced growth and altered androgen receptor target gene regulation in both LNCaP and C4-2 cell lines whereas it had no effect on the growth of the androgen receptor-negative PC-3 and DU145 prostate cancer cell lines. Although the requirement for androgens and androgen receptor in the development of prostate cancer is well established, our study implicates enhanced androgen receptor activity through elevated expression of SRC-1 in the development of more aggressive disease in men with prostate cancer.

Cellular interactions of the phosphorylated form of AKT in prostate cancer.

Phospho-Akt (P-Akt1) promotes proliferation and increased survival in vitro and plays an important role in prostate cancer (PCa) progression as well as the prediction of the probability of recurrence. In this study, the goal was to demonstrate the involvement and impact of P-Akt1 on cellular interactions, biomechanisms, and pathways in PCa. Tissue microarrays from 640 PCa patients were immunostained with various antibodies. Ki-67 was used to measure proliferation index, and terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labeling was used for apoptotic index. Increased expression of P-Akt1 was associated with an increased proliferation but inversely correlated with apoptotic index. Higher levels of P-Akt1 are associated with both higher levels of cytoplasmic p27 and higher levels of nuclear p27, suggesting an involvement in both cytoplasmic entrapment and phosphorylation of p27. P-Akt1 expression significantly correlated with nuclear and cytoplasmic staining of FHKR and GSK. The strongest correlations were found with the P- forms of both, suggesting enzyme kinetics in the latter. Here, phosphorylation is the principal method of FHKR and GSK inactivation. P-Akt1 correlated with nuclear transcription factor kappa B, suggesting a role in the inhibition through phosphorylation of nuclear transcription factor kappa B. The results of the current study are unique because of the scope of the markers and the size of the population used. In vitro- and in vivo-derived information of P-Akt1 and its downstream effectors demonstrates significant involvement in PCa. Our data suggest that PCa uses multiple mechanisms to regulate this pathway and substantiate the concept of redundancy in cancer pathway regulation. Consequently, new hypothesis-driven studies can be derived from this information.

Reduced infiltration of class A scavenger receptor positive antigen-presenting cells is associated with prostate cancer progression.

The class A macrophage scavenger receptor (SR-A) is expressed in antigen presenting cells and is involved in host immune responses. Germ-line mutation of this gene has been associated with increased risk of human prostate cancer. However, there is little known about its expression in normal or neoplastic human prostate tissues. Double immunofluorescent labeling with monoclonal antibodies to SR-A and specific macrophage and dendritic cell markers was used to identify cells expressing SR-A in human prostate tissues. SR-A immunohistochemical staining was performed on paraffin sections of normal prostate, prostatic intraepithelial neoplasia (PIN) lesions, and prostate cancers from radical prostatectomy specimens. SR-A was expressed in a subset of macrophages and dendritic cells that infiltrated prostatic tissues. The majority of SR-A-positive cells coexpressed CD68, and a relatively low percentage expressed S100 protein. The number of SR-A-positive cells was significantly increased in PIN as compared with normal prostatic tissue (P = 0.0176). In contrast, the number of SR-A-positive cells decreased with tumor progression. A lower SR-A-positive cell density was associated with higher clinical stage (rho = -0.26; P = 0.0234). Inverse associations were also found between SR-A density and positive lymph nodes (rho = -0.23; P = 0.0437), tumor size (rho = -0.31; P = 0.0100) and preoperative PSA levels (rho = -0.32; P = 0.0057). SR-A density is a significant predictor of disease-free survival after surgery univariately (P = 0.0003), as well as multivariately, adjusted for known clinical and pathological markers including preoperative prostate-specific antigen, clinical stage, Gleason score, surgical margin, extraprostatic extension, and seminal vesicle invasion, as well as lymph node metastasis (P = 0.0021). The preferential accumulation of SR-A-positive cells in PIN suggests a role for SR-A in the APC response to early malignancy. A reduction in the number of SR-A-positive cells demarcates tumor progression as indicated by clinical and pathological correlations. Our results additionally indicate that systematic measurement of SR-A density is a strong prognostic marker for clinical outcome after surgery.