Non-neoplastic Prostate Tissue Research Articles

MicroRNA in prostate cancer: Practical aspects.

In the last decade, microRNAs (miRNAs) have emerged as biomarkers for cancer diagnosis, prognosis, therapy and prediction of treatment response and have earned a promising role in prostate cancer (PCa) management. A plethora of studies has been conducted on miRNA expression in PCa compared to non-neoplastic prostatic tissue, in PCa of different histologic grades and pathologic stages, in castration resistance prostate cancer (CRPC), in metastatic disease and in response to therapy, with evidence pointing towards distinctive miRNAs differentially expressed in each of these phases. In addition to tissue, miRNA can be detected in blood, serum, and urine. The aim of this review is to survey studies conducted on human prostate tissue and biofluids and to consolidate trustworthy data on the role of miRNA in the occurrence and progression of PCa, with a delineation of differentially expressed miRNAs and an analysis of their association with PCa prognosis, progression to CRPC and metastatic disease, as well as their correlation with response to chemotherapy and hormonal therapy. Changes in circulating miRNAs may represent potentially useful non-invasive biomarkers for PCa diagnosis, staging and prediction of outcome.

Quantitative pharmacokinetic analysis of prostate cancer DCE-MRI at 3 T: comparison of two arterial input functions on cancer detection with digitized whole mount histopathological validation

Accurate pharmacokinetic (PK) modeling of dynamic contrast enhanced MRI (DCE-MRI) in prostate cancer (PCa) requires knowledge of the concentration time course of the contrast agent in the feeding vasculature, the so-called arterial input function (AIF). The purpose of this study was to compare AIF choice in differentiating peripheral zone PCa from non-neoplastic prostatic tissue (NNPT), using PK analysis of high temporal resolution prostate DCE-MRI data and whole-mount pathology (WMP) validation.This prospective study was performed in 30 patients who underwent multiparametric endorectal prostate MRI at 3.0T and WMP validation. PCa foci were annotated on WMP slides and MR images using 3D Slicer. Foci ≥0.5cm3 were contoured as tumor regions of interest (TROIs) on subtraction DCE (early-arterial - pre-contrast) images. PK analyses of TROI and NNPT data were performed using automatic AIF (aAIF) and model AIF (mAIF) methods. A paired t-test compared mean and 90th percentile (p90) PK parameters obtained with the two AIF approaches. Receiver operating characteristic (ROC) analysis determined diagnostic accuracy (DA) of PK parameters. Logistic regression determined correlation between PK parameters and histopathology.Mean TROI and NNPT PK parameters were higher using aAIF vs. mAIF (p<0.05). There was no significant difference in DA between AIF methods: highest for p90 volume transfer constant (Ktrans) (aAIF differences in the area under the ROC curve (Az) = 0.827; mAIF Az=0.93). Tumor cell density correlated with aAIF Ktrans (p=0.03).Our results indicate that DCE-MRI using both AIF methods is excellent in discriminating PCa from NNPT. If quantitative DCE-MRI is to be used as a biomarker in PCa, the same AIF method should be used consistently throughout the study.

The role of NFATc1 in prostate cancer progression: cyclosporine A and tacrolimus inhibit cell proliferation, migration, and invasion.

The functional role of nuclear factor of activated T-cells (NFAT), a well-characterized regulator of the immune response, in prostate cancer progression remains largely unknown. We aim to investigate biological significance of NFATc1, a NFAT isoform shown to function as an oncogene in a sarcoma model, in human prostate cancer. We first determined the expression levels of NFAT in prostate cell lines and tissue specimens. We then assessed the effects of NFAT inhibition via NFATc1-small interfering RNA (siRNA) as well as immunosuppressants including cyclosporine A (CsA) and tacrolimus (FK506) on prostate cancer cell proliferation, apoptosis, migration, and invasion in vitro and in vivo. Immunohistochemistry revealed that the expression levels of NFATc1 were significantly elevated in prostatic carcinomas, compared with non-neoplastic prostate or high-grade prostatic intraepithelial neoplasia tissues, and in high-grade (Gleason scores ≥7) tumors. NFATc1 positivity in carcinomas, as an independent prognosticator, also correlated with the risk of biochemical recurrence after radical prostatectomy. In prostate cancer cell lines, CsA and FK506 inhibited NFATc1 expression and its nuclear translocation, NFAT transcriptional activity, and the expression of c-myc, a downstream target of NFAT. NFAT silencing or treatment with these NFAT inhibitors resulted in decreases in cell viability/colony formation and cell migration/invasion, as well as increases in apoptosis, in androgen receptor (AR)-negative, AR-positive/androgen-sensitive, and AR-positive/castration-resistant lines. No significant additional inhibition in the growth of NFAT-siRNA cells by CsA and FK506 was seen, whereas these agents, especially FK506, further inhibited their invasion. In xenograft-bearing mice, CsA and FK506 significantly retarded tumor growth. Our results suggest that NFATc1 plays an important role in prostate cancer outgrowth. Thus, NFATc1 inactivation, especially using CsA and FK506, has the potential of being a therapeutic approach for not only hormone-naïve but also castration-resistant prostate cancers.

Nin one binding protein expression as a prognostic marker in prostate carcinoma

To investigate the prognostic value of expression levels of nin one binding protein (Nob1) in prostate carcinoma. Nob1 protein levels were evaluated by Western blot in samples from 40 prostate carcinomas and matched adjacent non-neoplastic prostate tissues. Nob1 expression was also assessed by immunohistochemistry in samples from 300 prostate carcinoma and matched adjacent non-neoplastic prostate tissues, as well as 20 benign prostatic hyperplasia samples. The findings were compared with clinical and pathologic parameters and patient outcome. Nob1 protein analysis showed significant differences between the prostate carcinomas and control groups tested. Immunohistochemical analysis showed that Nob1 positivity was higher in prostate carcinoma than that in paired adjacent non-cancerous tissues (58 vs 7 %, P < 0.001). Nob1 positivity was significantly associated with high Gleason scores and metastasis in patients. Nob1 expression was significantly associated with shorter biochemical recurrence-free survival (BCRFS). Multivariate analysis revealed that Nob1 is an independent marker for BCRFS. These findings provide evidence that Nob1 is an indicator of poor prognosis in prostate carcinoma.

STEAP1 protein overexpression is an independent marker for biochemical recurrence in prostate carcinoma

To investigate the prognostic value of expression levels of the genes STEAP1 and STEAP2, and of STEAP1 protein, in prostate carcinomas (PCa). STEAP1 and STEAP2 transcript levels were evaluated by RT-qPCR in samples from 35 PCa, 24 adjacent non-neoplastic prostate (AdjP) tissues, five cases of benign prostatic hyperplasia (BPH), and two histologically normal prostates (N). STEAP1 expression was assessed by immunohistochemistry in samples from 198 PCa, 76 AdjP, 22 BPH, and two N. The findings were compared with clinical and pathological parameters and patient outcome. STEAP1 and STEAP2 transcript analysis showed no differences between the groups tested. Although not significant, higher STEAP1 mRNA levels were detected in tumours with high Gleason scores and in patients who presented with biochemical recurrence (BCR). STEAP1 overexpression was detected in PCa, and was significantly associated with high-grade Gleason scores, seminal vesicle invasion, BCR, and worse outcome (metastasis or PCa-specific death). STEAP1 overexpression was significantly associated with shorter BCR-free survival. Multivariate analysis revealed that STEAP1 is an independent marker for BCR. These findings provide evidence that STEAP1 is a biomarker of worse prognosis in PCa patients.

Multidrug resistance protein 4 (MRP4) expression in prostate cancer is associated with androgen signaling and decreases with tumor progression

Multidrug resistance protein 4 (MRP4) is a transmembrane transport protein found in many cell types and is involved in substrate-specific transport of endogenous and exogenous substrates. Recently, it has shown to be expressed in prostate cancer cell lines and to be among the most commonly upregulated transcripts in prostate cancer, although a comprehensive expression analysis is lacking so far. We aimed to investigate its expression by immunohistochemistry in a larger cohort of neoplastic and nonneoplastic prostate tissues (n = 441) and to correlate its expression with clinicopathological parameters including PSA-free survival times and molecular correlates of androgen signaling (androgen receptor (AR), prostate-specific antigen (PSA), and forkhead box A (FoxA)). MRP4 is widely expressed in benign and neoplastic prostate epithelia, but its expression gradually decreases during tumor progression towards castrate-resistant disease. Concordantly, it correlated with conventional prognosticators of disease progression and-within the group of androgen-dependent tumors-with AR and FoxA expression. Moreover, lower levels of MRP4 expression were associated with shorter PSA relapse-free survival times in the androgen-dependent group. In benign tissues, we found zone-dependent differences of MRP4 expression, with the highest levels in the peripheral and central zones. Although MRP4 is known to be regulated in prostate cancer, this study is the first to demonstrate a gradual downregulation of MRP4 protein during malignant tumor progression and a prognostic value of this loss of expression.

Monocarboxylate transporter 2 (MCT2) as putative biomarker in prostate cancer

Monocarboxylate transporter 2 (MCT2) is a transmembrane protein involved in the transport of monocarboxylates such as pyruvate and lactate. In a previous study we described overexpression of MCT2 in prostate carcinoma raising the hypothesis of using MCT2 as a possible biomarker in prostate cancer. With the present study we aimed to compare the pattern of expression of MCT2 and alpha-methylacyl-CoA racemase (AMACR), in prostate carcinoma, PIN lesions, non-neoplastic prostate tissue, and normal prostate and compare their sensitivity and specificity. Also, we wanted to evaluate the value of using MCT2 in combination with AMACR and the negative markers 34βE12 or p63 to detect prostate cancer. A total of 349 cases, including prostate carcinoma, non-neoplastic prostate tissue and PIN lesions, from radical prostatectomies were examined by immunohistochemistry for AMACR, MCT2, p63, and 34βE12, using tissue microarrays (TMAs). Normal prostate from radical cystoprostatectomy was also studied. Our study revealed that MCT2, similarly to AMACR, was consistently expressed in prostate cancer regardless of the Gleason score. In combination with AMACR and p63 or 34βE12, MCT2 helped to improve the diagnosis of prostate carcinoma. Also, overexpression of MCT2 as well as AMACR in PIN lesions may indicate the involvement of these two proteins in prostate cancer initiation. We provided evidence for the presence of MCT2 in prostate cancer, selectively labeling malignant glands. Importantly, assessment of MCT2 together with AMACR, along with the negative markers, highly increases the accuracy in prostate cancer diagnosis.

Clinical Utility of an Epigenetic Assay to Detect Occult Prostate Cancer in Histopathologically Negative Biopsies: Results of the MATLOC Study

Concern about possible false-negative prostate biopsy histopathology findings often leads to rebiopsy. A quantitative methylation specific polymerase chain reaction assay panel, including GSTP1, APC and RASSF1, could increase the sensitivity of detecting cancer over that of pathological review alone, leading to a high negative predictive value and a decrease in unnecessary repeat biopsies. The MATLOC study blindly tested archived prostate biopsy needle core tissue samples of 498 subjects from the United Kingdom and Belgium with histopathologically negative prostate biopsies, followed by positive (cases) or negative (controls) repeat biopsy within 30 months. Clinical performance of the epigenetic marker panel, emphasizing negative predictive value, was assessed and cross-validated. Multivariate logistic regression was used to evaluate all risk factors. The epigenetic assay performed on the first negative biopsies of this retrospective review cohort resulted in a negative predictive value of 90% (95% CI 87-93). In a multivariate model correcting for patient age, prostate specific antigen, digital rectal examination and first biopsy histopathological characteristics the epigenetic assay was a significant independent predictor of patient outcome (OR 3.17, 95% CI 1.81-5.53). A multiplex quantitative methylation specific polymerase chain reaction assay determining the methylation status of GSTP1, APC and RASSF1 was strongly associated with repeat biopsy outcome up to 30 months after initial negative biopsy in men with suspicion of prostate cancer. Adding this epigenetic assay could improve the prostate cancer diagnostic process and decrease unnecessary repeat biopsies.

Arachidonic acid metabolism in human prostate cancer

The arachidonic acid pathway is important in the development and progression of numerous malignant diseases, including prostate cancer. To more fully evaluate the role of individual cyclooxygenases (COXs), lipoxygenases (LOXs) and their metabolites in prostate cancer, we measured mRNA and protein levels of COXs and LOXs and their arachidonate metabolites in androgen-dependent (LNCaP) and androgen-independent (PC-3 and DU145) prostate cancer cell lines, bone metastasis-derived MDA PCa 2a and MDA PCa 2b cell lines and their corresponding xenograft models, as well as core biopsy specimens of primary prostate cancer and nonneoplastic prostate tissue taken ex vivo after prostatectomy. Relatively high levels of COX-2 mRNA and its product PGE2 were observed only in PC-3 cells and their xenografts. By contrast, levels of the exogenous 12-LOX product 12-HETE were consistently higher in MDA PCa 2b and PC-3 cells and their corresponding xenograft tissues than were those in LNCaP cells. More strikingly, the mean endogenous level of 12-HETE was significantly higher in the primary prostate cancers than in the nonneoplastic prostate tissue (0.094 vs. 0.010 ng/mg protein, respectively; p=0.019). Our results suggest that LOX metabolites such as 12-HETE are critical in prostate cancer progression and that the LOX pathway may be a target for treating and preventing prostate cancer.

Effect of neoadjuvant docetaxel treatment for locally advanced prostate cancer on miRNA expression: A pilot study.

139 Background: Taxanes are microtubule-stabilizing drugs used investigationally in adjuvant and neoadjuvant settings of prostate cancer (PCA) treatment in an attempt to improve systemic control of high risk disease. Understanding mechanism of response to taxanes is an essential step in developing novel combination therapies to improve PCA response rates. MicroRNAs (miRNAs) are small noncoding RNA molecules that negatively regulate gene expression by binding target messenger RNAs and inhibiting their stability and/or translation. In cancer miRNAs can act as oncogenes and/or tumor suppressor genes. The objective of our study was to identify miRNAs that are affected by neoadjuvant docetaxel in high-risk PCA. Methods: Whole cell RNA was extracted from formalin-fixed paraffin-embedded (FFPE) radical prostatectomy specimens from 8 patients with high grade PCA treated with neoadjuvant docetaxel, 8 high grade untreated PCA and their corresponding untreated non-neoplastic tissue. Tumors were matched by Gleason score, patient age and year of surgery. The expression of 88 cancer-associated miRNAs was then quantified using a PCR-based miRNA microarray assay. Results: Thirty-eight (43%) of the 88 analyzed miRNAs (including miR-205, miR-222, and miR-1) were sgnificantly downregulated in untreated PCA compared with untreated non-neoplastic tissue, and one (miR-183) was upregulated. Twenty (23%) miRNAs (including miR-218, miR-124, and let-7b) were significantly upregulated in treated compared to untreated PCA. The expression levels of 16 of these miRNAs (including miR-9, miR-133b, and miR-27b) were reverted to values similar to untreated non-neoplastic prostatic tissue, as a result of docetaxel treatment. Conclusions: Our results indicate a potential role of miRNAs in PCA response to taxanes. A subset of miRNAs are downregulated in untreated tumors but upregulated in treated PCA to the levels compared to untreated non-neoplastic tissue, suggesting a miRNA modulation towards a non-neoplastic expression profile with neoadjuvant docetaxel treatment. Further studies are underway to evaluate the miRNA-mediated effects of taxanes in PCA.

Therapy‐associated effects in the prostate gland

Diverse therapies are used to treat both benign prostatic hyperplasia and adenocarcinoma. Transurethral resection, a common surgical procedure, may give rise to characteristic necrobiotic granulomas that manifest in subsequent pathology samples. Radiation and hormone therapy have traditionally been used in prostatic adenocarcinoma. Morphological effects are often identified in needle biopsy specimens, transurethral resectates, and radical prostatectomy specimens. A range of histological changes are noted in the non-neoplastic prostate tissue, as well as in the pre-neoplastic and carcinomatous areas. Other ablative therapies, such as cryotherapy, and emerging focal therapies, including high-intensity focused ultrasound, photodynamic therapy, and interstitial laser thermotherapy, may have morphological effects on prostate tissue. It is important for the pathologist to be aware of the spectrum of histological changes affecting the prostate gland post-therapy. The treatment effects may obscure residual carcinoma, and make measurements of tumour extent and stage difficult. Furthermore, some therapies can profoundly alter the neoplastic glands to such an extent that Gleason scoring is no longer valid. As new therapies are developed for prostate cancer, it is important to document their effects on benign and malignant prostate tissue and to understand possible implications for traditional prognostic factors, especially Gleason grade.

ERG gene rearrangement status in prostate cancer detected by immunohistochemistry

TMPRSS2-ERG, the most common gene fusion in prostate cancer, is associated with expression of a truncated protein product of the oncogene ERG. A novel anti-ERG monoclonal antibody has been recently characterized. We investigated the correlation between ERG rearrangement assessed by fluorescence in situ hybridization (FISH) and ERG expression detected by immunohistochemistry in a large cohort of patients treated with radical prostatectomy for clinically localized prostate cancer. Thirteen tissue microarrays comprising 305 tumors and a subset of 112 samples of nonneoplastic prostatic tissue were assessed for ERG rearrangement status by FISH and for ERG expression by immunohistochemistry. Accuracy of ERG detection by immunohistochemistry in predicting ERG status as assessed by FISH (criterion standard) was calculated in terms of sensitivity, specificity, positive and negative predictive values. Of 305 tumor foci, 103 (34%) showed ERG rearrangement by FISH. ERG was detected by immunohistochemistry in 100 (33%) cases, 99 of which were FISH positive. ERG detection by immunohistochemistry demonstrated a sensitivity and specificity of 96% and 99%, respectively, with positive and negative predictive values of 99% and 98%, respectively. None of the 112 samples of nonneoplastic prostatic tissue was rearranged by FISH or showed any ERG expression. In conclusion, ERG detection by immunohistochemistry in prostate cancer was highly predictive of ERG rearrangement as assessed by FISH in a large cohort of prostatectomy patients. Given the high yield and the easier task of performing immunohistochemistry vs. FISH, ERG assessment by immunohistochemistry may be useful for characterizing ERG status in prostate cancer.

Impact of the EpCAM expression on biochemical recurrence-free survival in clinically localized prostate cancer

BackgroundThe epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein that was originally identified as a marker for carcinoma, attributable to its high expression on rapidly proliferating tumors of epithelial origin. The role of EpCAM is not limited to cell adhesion but includes diverse processes such as signaling, cell migration, proliferation, and differentiation. ObjectiveSeveral studies investigated EpCAM expression in prostate carcinoma but none of them confirmed its prognostic role. The aim of our study was to investigate EpCAM expression and its relationship with established prognostic features in prostate carcinoma. Materials and methodsThe study included a cohort of 102 patients treated with radical prostatectomy for clinically localized prostate carcinoma. Immunohistochemistry was performed to evaluate the EpCAM expression in prostate cancer and non-neoplastic prostate tissue. The percentage of positively stained carcinoma and benign glands was examined in the whole mount of the chosen slide. ResultsThe extent of EpCAM expression was significantly higher in malignant than in benign prostatic tissue (P < 0.001). EpCAM expression in prostate cancer was associated with established features indicative of worse prognosis, such as preoperative (P = 0.009) and postoperative (P = 0.004) Gleason score and follow-up time (P < 0.001). Patients with higher preoperative and postoperative Gleason score and short follow-up time had tumors with a significantly higher expression of EpCAM. Negative correlation of follow-up time and EpCAM expression indicated that tumors in patients with biochemical recurrence (BCR) harbored higher EpCAM expression. Moreover, expression of EpCAM was significantly higher in patients with BCR compared with patients without BCR (P < 0.001). Tumors in T3 stage of the disease showed significantly higher EpCAM expression compared with T2 tumors (P = 0.002). Univariate (P < 0.001) and multivariate (P < 0.001) analyses showed that EpCAM expression was a significant predictor of shorter biochemical recurrence free-survival. ConclusionOur results confirmed high level of EpCAM expression in prostate cancer and support its potential role in prostatic cancer progression. In addition, EpCAM could serve as an additional prognostic marker for the recognition of patients with an increased risk of disease recurrence that need introduction of secondary therapy.

BAG3 protein delocalisation in prostate carcinoma

Despite the progressive increase of early diagnosis, a subset of prostate cancers show a metastasizing and lethal course, not always predictable upon the traditional prognostic parameters. The object of this study was to investigate the role of the survival co-chaperone protein BAG3 as a new prognostic marker for prostate cancer. BAG3 was detected by immunohistochemistry in 55 specimens of surgically removed prostate carcinomas and in 15 surgical specimens of non-neoplastic prostate tissues. Results were compared with clinic-pathological data and outcome of patients and statistically evaluated. BAG3 resulted expressed in all the cases: Non-neoplastic prostate tissue showed a cytoplasmatic staining with apical reinforcement, a finding which appears consistent with the reported connection of the protein with the membrane focal cell-adhesion complexes. In prostate carcinomas, BAG3 showed a progressive decrease of the expression level from well- to low-differentiated carcinoma, coupled with the loss of polarisation of the signal in metastasizing cases. These results indicate that BAG3 intra-cytoplasmic delocalisation is a specific feature of cancer versus non-neoplastic prostate and a candidate new marker for prediction of prostate cancer invasiveness and behaviour.

Analysis of gene expression in prostate cancer epithelial and interstitial stromal cells using laser capture microdissection

BackgroundThe prostate gland represents a multifaceted system in which prostate epithelia and stroma have distinct physiological roles. To understand the interaction between stroma and glandular epithelia, it is essential to delineate the gene expression profiles of these two tissue types in prostate cancer. Most studies have compared tumor and normal samples by performing global expression analysis using a mixture of cell populations. This report presents the first study of prostate tumor tissue that examines patterns of differential expression between specific cell types using laser capture microdissection (LCM).MethodsLCM was used to isolate distinct cell-type populations and identify their gene expression differences using oligonucleotide microarrays. Ten differentially expressed genes were then analyzed in paired tumor and non-neoplastic prostate tissues by quantitative real-time PCR. Expression patterns of the transcription factors, WT1 and EGR1, were further compared in established prostate cell lines. WT1 protein expression was also examined in prostate tissue microarrays using immunohistochemistry.ResultsThe two-step method of laser capture and microarray analysis identified nearly 500 genes whose expression levels were significantly different in prostate epithelial versus stromal tissues. Several genes expressed in epithelial cells (WT1, GATA2, and FGFR-3) were more highly expressed in neoplastic than in non-neoplastic tissues; conversely several genes expressed in stromal cells (CCL5, CXCL13, IGF-1, FGF-2, and IGFBP3) were more highly expressed in non-neoplastic than in neoplastic tissues. Notably, EGR1 was also differentially expressed between epithelial and stromal tissues. Expression of WT1 and EGR1 in cell lines was consistent with these patterns of differential expression. Importantly, WT1 protein expression was demonstrated in tumor tissues and was absent in normal and benign tissues.ConclusionsThe prostate represents a complex mix of cell types and there is a need to analyze distinct cell populations to better understand their potential interactions. In the present study, LCM and microarray analysis were used to identify novel gene expression patterns in prostate cell populations, including identification of WT1 expression in epithelial cells. The relevance of WT1 expression in prostate cancer was confirmed by analysis of tumor tissue and cell lines, suggesting a potential role for WT1 in prostate tumorigenesis.

Abstract 1172: RARB is a biomarker of poor prognosis in prostate carcinomas

Abstract Purpose: Despite the advances in prostate carcinomas (PCa) management, about 30% of the patients who undergo radical prostatectomy presented biochemical recurrence (BCR). BCR is considered an unfavorable prognostic factor followed by clinical disease progression. The current prognostic markers in PCa are unable detect correctly who is at risk for BCR. Hypermethylation at RARB and RASSF1A genes have been associated with worse prognosis in PCa. The current study aimed to evaluate RARB, and RASSF1A hypermethylation frequencies in prostate carcinoma (PCa) and to correlate these alterations with down-regulation at transcriptional and protein levels and with clinical outcome. Methods: Methylation patterns of RARB and RASSF1A were determined by methylation-specific PCR in 68 PCa samples and 27 non-neoplastic prostate tissues. Gene expression was evaluated by quantitative RT-PCR in 73 PCa, 15 adjacent non-neoplastic prostate tissues (AdjP) and two normal prostate (N). Protein expression was evaluated in an independent PCa cohort (n=141) with long-term follow-up period. The findings were associated with clinicopathological parameters and BCR-free survival (BRFS). Results: RARB and RASSF1A genes were hypermethylated in PCa (P &amp;lt;0.0001 and P = 0.0017, respectively). RASSF1A mRNA and protein levels were similar in PCa and AdjP samples. Down-expression of RARβ in transcript (P=0.001) and protein (P=0.0007) levels were detected in PCa. Lower mRNA levels were associated with RARB hypermethylation. Nuclear and cytoplasmic RARβ protein expression was detected in tumor tissues. Multivariate analysis demonstrated that cytoplasmic RARβ immunostaining was independently associated with decreased BRFS (P=0.005, HR=2.314). Conclusions: RARB hypermethylation seems to be one of the mechanisms involved in RARβ down-expression in PCa. Cytoplasmic RARβ protein is an independent predictor of poor prognosis that may be considered a new biomarker in prostate cancer providing, therefore, relevant information for patient management. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1172.

Hypermethylation of MCAM gene is associated with advanced tumor stage in prostate cancer

DNA methylation has emerged as a promising biomarker for prostate cancer detection. In this report, we screened 36 candidate genes generated by a bioinformatic analysis of the human genome, and found that the melanoma cell adhesion molecule (MCAM) was an excellent candidate for cancer-specific methylation in prostate cancer. Direct sequencing of bisulfite-treated genomic DNA, conventional methylation-specific PCR (MSP), real-time quantitative methylation-specific PCR, immunohistochemistry, colony formation assay, and statistical analysis. We found that the melanoma cell adhesion molecule (MCAM) gene promoter was specifically methylated in prostate cancer cell lines and primary prostate cancer (PCa) but not in non-neoplastic prostate (BPH) tissues by direct sequencing of bisulfite-treated genomic DNA and conventional methylation-specific PCR (MSP). Further analysis with quantitative MSP showed greater hypermethylation of the MCAM promoter (80%, 70/88) in primary prostate cancer compared to 12.5% (3/24) in BPH. Prostatic intraepithelial neoplasias (PIN), potential precursors of prostate carcinoma, showed an intermediate methylation rate of 23% (7/30). We further observed that MCAM promoter methylation was directly correlated with tumor stage (pT3+pT4) (P = 0.001) and Gleason score (P = 0.018) in primary prostate carcinoma. Our results suggest that MCAM promoter hypermethylation deserves further attention as a potential diagnostic prostatic DNA marker in human prostate cancer.

The Usefulness of the Detection of GSTP1 Methylation in Urine as a Biomarker in the Diagnosis of Prostate Cancer

Prostate cancer has a unique set of problems associated with its early detection and diagnosis that might be aided by the addition of molecular markers, such as DNA hypermethylation. DNA methylation is an important epigenetic mechanism of gene regulation that has a critical role in normal developmental processes. Aberrant DNA methylation is a hallmark of carcinogenesis and GSTP1 hypermethylation is the most common molecular alteration in human prostate cancer. To our knowledge the clinical usefulness of the detection of gene methylation is yet to be established. We evaluated GSTP1 hypermethylation in urine collected after prostatic massage and in core needle biopsies from 100 men referred for diagnostic biopsy. Methylation of GSTP1 in urine specimens had 75% sensitivity and 98% specificity for prostate cancer. GSTP1 methylation in the biopsy had 88% specificity and 91% sensitivity. Interestingly we observed a higher frequency of GSTP1 methylation in the urine of men with stage III vs II disease (100% vs 20%, p = 0.05). This study suggests that the detection of GSTP1 methylation in prediagnostic urine may improve the specificity of PSA and help distinguish men with prostate cancer from those with benign prostatic hyperplasia. This finding should be further explored in a larger, prospective screening trial.

Locked Nucleic Acids Can Enhance the Analytical Performance of Quantitative Methylation-Specific Polymerase Chain Reaction

Aberrant DNA methylation of tumor suppressor genes is a frequent epigenetic event that occurs early in tumor progression. Real-time quantitative methylation-specific polymerase chain reaction (QMSP) assays can provide accurate detection and quantitation of methylated alleles that may be potentially useful in diagnosis and risk assessment for cancer. Development of QMSP requires optimization to maximize analytical specificity and sensitivity for the detection of methylated alleles. However, in some cases challenges encountered in primer and probe design can make optimization difficult and limit assay performance. Locked nucleic acids (LNAs) demonstrate increased affinity and specificity for their cognate DNA sequences. In this proof-of-principle study, LNA residues were incorporated into primer and probe design to determine whether LNA-modified oligonucleotides could enhance the analytical performance of QMSP for IGSF4 promoter methylation in human cancer cell lines using either SYBR Green or fluorogenic probe detection methods. Use of LNA primers in QMSP with SYBR Green improved analytical specificity for methylated alleles and eliminated the formation of nonspecific products because of mispriming from unmethylated alleles. QMSP using LNA probe and primers showed an increased amplification efficiency and maximum fluorescent signal. QMSP with LNA oligonucleotides and either detection method could reliably detect five genome equivalents of methylated DNA in 1000- to 10,000-fold excess unmethylated DNA. Thus, LNA oligonucleotides can be used in QMSP optimization to enhance analytical performance.

Low frequency of BK virus in prostatic adenocarcinomas

BK virus (BKV) exhibits many oncogenic properties and has been associated with a variety of tumors in humans. BKV has not been well studied in the context of prostate neoplasia; however, an association of BKV with prostatic adenocarcinoma has been suggested based on the detection of viral DNA sequences and expression of viral proteins in clinical samples. To further investigate the reported association of BKV with prostatic adenocarcinoma and the potential role of the virus in prostate tumorigenesis, 30 cases of adenocarcinoma of the prostate were analyzed for evidence of BKV infection by in situ hybridization and immunohistochemistry. In situ hybridization analysis detected BKV DNA in 2 of 30 (7%) prostatic adenocarcinomas, with positive signals focally identified in less than 1% of the neoplastic cells in both cases. However, none of the tumors evaluated demonstrated evidence of BKV large tumor antigen expression by immunohistochemistry. Among prostatic adenocarcinomas that showed no evidence of BKV infection, BKV DNA was focally observed in the adjacent non-neoplastic prostate tissue in four cases by in situ hybridization in the absence of BKV large tumor antigen immunoreactivity. The findings of the present study indicate rare cases of prostatic adenocarcinoma may be associated with BKV infection. However, lack of localization of BKV to a large population of the neoplastic cells and absence of BKV large tumor antigen expression suggest that the virus does not play a role in the pathogenesis of prostate cancer.