A novel method for detection of exfoliated prostate cancer cells in urine by RNA in situ hybridization.

BACKGROUND: In the current study, we explore the feasibility of detecting exfoliated prostate cancer cells in urine using an RNA in situ hybridization (RISH) assay. We hypothesized that robust and specific labeling of prostate cancer cells could be achieved in post-digital rectal examination (DRE) urine samples using RISH. METHODS: We focused on method development, optimization, and analytical evaluation of RISH-based detection of prostate cancer in urine. We optimized a sample collection, processing, and target detection workflow for urine cytology specimens in conjunction with RNA target detection by RISH. We screened a panel of 11 prostate-specific RNA targets, and selected NKX3-1 and PRAC1 as markers for cells of prostate origin and PCA3 as a marker of prostate malignancy. Following analytical validation of a multiplexed NKX3-1/PRAC1/PCA3 assay, we evaluated whether prostate cancer cells can be detected in a pilot cohort of 19 post-DRE specimens obtained from men diagnosed with prostate cancer. RESULTS: Using cytology specimens prepared from spiked urine samples, we established the analytical validity of the RISH assay for detection and visualization of prostate cells in urine. Cells of prostate origin could be readily and specifically identified and separated into benign and malignant cell populations based on the multiplex test that consisted of markers specific for prostate cells (NKX3-1, PRAC1) and prostate cancer cells (PCA3). Upon evaluation of post-DRE urine from a pilot cohort of prostate cancer patients, we identified 11 samples in which prostate cells were present, 6 of which were also positive for prostate cancer cells. CONCLUSIONS: Multiplex RISH enables the direct visualization and molecular characterization of individual exfoliated prostate cells in urine. This proof-of-principle study provides evidence supporting the application of RISH as a potential noninvasive tool for prostate cancer detection.

Identification of miR-30b-3p and miR-30d-5p as direct regulators of androgen receptor signaling in prostate cancer by complementary functional microRNA library screening.

The Androgen Receptor (AR) plays a key role in prostate biology and in the progression of prostate cancer (PCa) to castration resistance. The role of microRNAs (miRNAs) in aberrant AR signaling have not been fully characterized. Here we screened a library of 810 miRNA mimics to identify miRNAs that alter AR activity in complementary functional assays including protein lysate microarray (LMA) quantification of AR and PSA protein levels, AR transcriptional reporter activity, and AR-positive PCa cell viability. Candidate AR-regulating miRNAs were verified through AR transcriptional reporter and cell viability assays. MiRNA binding sites were found within the AR 3'-untranslated region (UTR) and within the AR and AR-V7 coding regions. MiRNA activity was characterized by western blotting, 3'-UTR reporter assay, and AR-GFP and AR-V7-GFP reporter assays. Results uncovered miR-30 family members as direct AR inhibitors. Inhibition of endogenous miR-30b-3p and miR-30d-5p enhanced AR expression and androgen-independent cell growth. Droplet digital RT-PCR quantification of miR-30c-5p and miR-30d-5p revealed significantly reduced levels in metastatic castration resistant PCa (CRPC), when compared to healthy prostate tissues. MiR-30d-5p levels were inversely correlated with AR activity, as measured by PSA mRNA, in metastatic CRPC. Collectively, these studies provide a comprehensive evaluation of AR-regulating miRNAs in PCa.

Role of biobanking in urology: a review.

In the current era of individualized medicine, a biorepository of human samples is essential to support clinical and translational research. There have been limited efforts in this arena within the field of urology, as cost, logistical and ethical issues represent significant deterrents to biobanking. The Johns Hopkins Brady Urological Institute Biorepository was founded in 1994 as a resource to facilitate discovery. Since its inception, the biorepository has enabled numerous research endeavours including pivotal trials leading to the regulatory approval of four diagnostic tests for prostate cancer. In the present review, we discuss the current state of biobanking within urology, outline the specific ethical and financial challenges to biobanking as well as solutions, and describe the operations of a successful urological biorepository.

Cyr61 is regulated by cAMP-dependent protein kinase with serum levels correlating with prostate cancer aggressiveness.

BACKGROUND: Cysteine-rich angiogenic inducer 61 (Cyr61) is an extracellular matrix protein involved in the transduction of growth factor and hormone signaling. Previously, we demonstrated that Cyr61 was highly expressed in prostate cancer (PCa) but that the expression levels were associated with a lower risk of PCa recurrence. In the present study, we demonstrate that serum Cyr61 is a potential biomarker that correlates with PCa aggressiveness. Furthermore, we also explore the potential mechanism underlying the changes in Cyr61 expression during PCa progression. METHODS: Cyr61 concentrations in the medium from PCa cell lines and in serum samples obtained from PCa patients were measured by sandwich ELISA. Serum Cyr61 levels were correlated with disease characteristics and the association between Cyr61 expression changes by several types of stimulation or stress and cAMP/cAMP-dependent protein kinase (PKA) pathway were examined. RESULTS: There was a positive correlation between Cyr61 levels in cell supernatants and mRNA expression in these cell lines. Serum Cyr61 levels were significantly higher in non-organ-confined PCa patients (116.3 ± 140.2 ng/ml) than in organ-confined PCa patients (79.7 ± 56.1 ng/ml) (P = 0.031). Cyr61 expression was up-regulated in response to both lysophosphatidic acid and androgen treatments which promoted PCa cell invasion. Serum starvation and phosphoinositide-3-kinase inhibition also resulted in Cyr61 up-regulation; however, they suppressed cell proliferation. Cyr61 up-regulation was correlated with an increase in cAMP and suppressed by PKA inhibition. CONCLUSIONS: These findings suggest that Cyr61 expression in PCa is regulated by the cAMP/PKA pathway and that circulating Cyr61 levels are a potential serum-based biomarker for characterizing PCa.

Purine-rich element binding protein (PUR) alpha induces endoplasmic reticulum stress response, and cell differentiation pathways in prostate cancer cells.

BACKGROUND: Following androgen ablation treatment for advanced prostate cancer, almost all men relapse after a period of initial response to therapy, which eventually is life threatening. We have previously found that purine-rich element binding protein, PURalpha, was significantly repressed in androgen-independent prostate cancer cell lines in comparison to an androgen-dependent line. Moreover, over-expressing PURalpha in androgen-independent prostate cancer cells attenuated their cell proliferation. The aim of the studies described here was to uncover some of the mechanisms by which over-expression of PURalpha attenuates cell proliferation. METHODS: A set of common genes induced by over-expressing PURalpha both in PC3 and LNCaP cells was analyzed by DNA microarray. The results were then validated utilizing quantitative reverse transcription-PCR. Using a 5.3-kb region of the PSA promoter containing androgen response elements, the participation of PURalpha in androgen regulated gene expression was determined. RESULTS: Genes involved in stress response and cell differentiation were induced in cells over-expressing PURalpha. Some of the genes that are targets of androgen regulation are also induced. Most strikingly, ectopic expression of PURalpha induced transcriptional activity of the 5.3-kb PSA promoter containing androgen response elements, without androgen stimulation. CONCLUSION: Based upon the consideration that some of the genes involved in cell stress and differentiation are also regulated by androgens our data suggest that PURalpha shares some common pathways regulated by the androgen receptor. These findings suggest that regulation of PURalpha expression in prostate cancer cells may serve as a therapeutic target for hormone refractory prostate cancer.

The potential role of purine-rich element binding protein (PUR) alpha as a novel treatment target for hormone-refractory prostate cancer.

BACKGROUND: Hormonal therapy for advanced prostate cancer is typically effective at first, but almost all men suffer refractory disease which often is life threatening. The nuclear matrix comprises not only of the structural elements of the nucleus, but is associated with many components of the molecular machinery. Our aim is to find novel targets for the treatment of hormone-refractory prostate cancer (HRPC) by focusing on the composition of the nuclear matrix proteins (NMPs). METHODS: LN96 cells were established at our Institution after long-term culturing of LNCaP cells under androgen deprived conditions. The composition of NMPs of LNCaP cells and LN96 cells were analyzed by two-dimensional (2D) electrophoresis and spots differentially expressed were investigated by mass spectrometry for identification. Among the spots identified, we analyzed the potential functional role of the identified proteins in prostate cancer cells by establishing stable overexpressed cells. RESULTS: We found that purine-rich element binding protein (PUR)alpha was significantly repressed not only in NMPs but also in total protein and mRNA levels of LN96 cells in comparison to LNCaP cells under the same steroid deprived conditions. Moreover, PURalpha was decreased in its expression both at the protein and mRNA levels in the androgen-independent prostate cancer cell lines, PC3 and DU145 in comparison to LNCaP cells. Stably overexpressing PURalpha in PC3 and DU145 cells negatively regulates cell proliferation, resulting in decreases in PCNA expression. CONCLUSION: Further dissection of the role of PURalpha in cell growth regulation may reveal a novel target for HRPC.

Sun2 is a novel mammalian inner nuclear membrane protein.

Sun protein (Sun1 and Sun2) cDNAs were previously cloned based on the homology of their C-terminal regions (SUN (Sad1 and UNC) domain) with the Caenorhabditis elegans protein UNC-84 whose mutation disrupts nuclear migration/positioning. In this study, we raised an anti-Sun2 serum and identified Sun2 in mammalian cells. In HeLa cells, Sun2 displays a nuclear rim-like pattern typical for a nuclear envelope protein. The Sun2 antibody signal co-localizes with nuclear pore and INM markers signals. The rim-like pattern was also observed with the recombinant full-length Sun2 protein fused to either EGFP or V5 epitopes. In addition, we found that a recombinant truncated form of Sun2, extending from amino acids 26 to 339, is sufficient to specify the nuclear envelope localization. Biochemical analyses show that Sun2 is an 85-kDa protein that is partially insoluble in detergent with high salt concentration and in chaotropic agents. Furthermore, Sun2 is enriched in purified HeLa cell nuclei. Electron microscopy analysis shows that Sun2 localizes in the nuclear envelope with a sub-population present in small clusters. Additionally, we show that the SUN domain of Sun2 is localized to the periplasmic space between the inner and the outer nuclear membranes. From our data, we conclude that Sun2 is a new mammalian inner nuclear membrane protein. Because the SUN domain is conserved from fission yeast to mammals, we suggest that Sun2 belongs to a new class of nuclear envelope proteins with potential relevance to nuclear membrane function in the context of the involvement of its components in an increasing spectrum of human diseases.