Blood and tissue biomarkers in prostate cancer: state of the art

Proteomic Profiling of Serum-Derived Exosomes from Ethnically Diverse Prostate Cancer Patients

Prostate cancer (PCa) remains the most frequently diagnosed male malignancy in Western countries and the second most common cause of male cancer death in the United States. The relatively elevated PCa incidence and mortality among African American men makes this cancer type a challenging health disparity disease. To increase the chance for successful trea tment, earlier detection and prediction of tumor aggress iveness will be important and need to be resolved. This study demonstrates that small membrane-bound vesicles shed from the tumor called exosomes contain ethnically and tumor-specific biomarkers, and could be exploited for their diagnostic and therapeutic potential.

Analysis of the Human Prostate-Specific Proteome Defined by Transcriptomics and Antibody-Based Profiling Identifies TMEM79 and ACOXL as Two Putative, Diagnostic Markers in Prostate Cancer

To better understand prostate function and disease, it is important to define and explore the molecular constituents that signify the prostate gland. The aim of this study was to define the prostate specific transcriptome and proteome, in comparison to 26 other human tissues. Deep sequencing of mRNA (RNA-seq) and immunohistochemistry-based protein profiling were combined to identify prostate specific gene expression patterns and to explore tissue biomarkers for potential clinical use in prostate cancer diagnostics. We identified 203 genes with elevated expression in the prostate, 22 of which showed more than five-fold higher expression levels compared to all other tissue types. In addition to previously well-known proteins we identified two poorly characterized proteins, TMEM79 and ACOXL, with potential to differentiate between benign and cancerous prostatic glands in tissue biopsies. In conclusion, we have applied a genome-wide analysis to identify the prostate specific proteome using transcriptomics and antibody-based protein profiling to identify genes with elevated expression in the prostate. Our data provides a starting point for further functional studies to explore the molecular repertoire of normal and diseased prostate including potential prostate cancer markers such as TMEM79 and ACOXL.

Prostate cell lines as models for biomarker discovery: performance of current markers and the search for new biomarkers

BACKGROUND

Prostate cancer cell lines have been used in the search for biomarkers that are suitable for prostate cancer diagnosis. Unfortunately, many cell line studies have only involved single cell lines, partially characterized cell lines or were performed without controls, and this may have been detrimental to effective biomarker discovery. We have analyzed a panel of prostate cancer and nonmalignant control cell lines using current biomarkers and then investigated a set of prospective endosomal and lysosomal proteins to search for new biomarkers.

METHODS

Western blotting was used to define the amount of protein and specific molecular forms in cell extracts and culture media from a panel of nonmalignant (RWPE-1, PNT1a, PNT2) and prostate cancer (22RV1, CaHPV10, DU-145, LNCaP) cell lines. Gene expression was determined by qRT-PCR.

RESULTS

HPV-18 transfected cell lines displayed a different pattern of protein and gene expression when compared to the other cell lines examined, suggesting that these cell lines may not be the most optimal for prostate cancer biomarker discovery. There was an increased amount of prostatic acid phosphatase and kallikrein proteins in LNCaP cell extracts and culture media, but variable amounts of these proteins in other prostate cancer cell lines. There were minimal differences in the amounts of lysosomal proteins detected in prostate cancer cells and culture media, but two endosomal proteins, cathepsin B and acid ceramidase, had increased gene and protein expression, and certain molecular forms showed increased secretion from prostate cancer cells (P ≤ 0.05). LIMP-2 gene and protein expression was significantly increased in prostate cancer compared to nonmalignant cell lines (P ≤ 0.05).

CONCLUSIONS

While the existing prostate cancer biomarkers and lysosomal proteins investigated here were not able to specifically differentiate between a panel of nonmalignant and prostate cancer cell lines, endosomal proteins showed some discriminatory capacity. LIMP-2 is a critical regulator of endosome biogenesis and the increased expression observed in prostate cancer cells indicated that other endosome related proteins may also be upregulated and could be investigated as novel biomarkers.

Diagnostic and prognostic utility of a DNA hypermethylated gene signature in prostate cancer

We aimed to identify a prostate cancer DNA hypermethylation microarray signature (denoted as PHYMA) that differentiates prostate cancer from benign prostate hyperplasia (BPH), high from low-grade and lethal from non-lethal cancers. This is a non-randomized retrospective study in 111 local Asian men (87 prostate cancers and 24 BPH) treated from 1995 to 2009 in our institution. Archival prostate epithelia were laser-capture microdissected and genomic DNA extracted and bisulfite-converted. Samples were profiled using Illumina GoldenGate Methylation microarray, with raw data processed by GenomeStudio. A classification model was generated using support vector machine, consisting of a 55-probe DNA methylation signature of 46 genes. The model was independently validated on an internal testing dataset which yielded cancer detection sensitivity and specificity of 95.3% and 100% respectively, with overall accuracy of 96.4%. Second validation on another independent western cohort yielded 89.8% sensitivity and 66.7% specificity, with overall accuracy of 88.7%. A PHYMA score was developed for each sample based on the state of methylation in the PHYMA signature. Increasing PHYMA score was significantly associated with higher Gleason score and Gleason primary grade. Men with higher PHYMA scores have poorer survival on univariate (p = 0.0038, HR = 3.89) and multivariate analyses when controlled for (i) clinical stage (p = 0.055, HR = 2.57), and (ii) clinical stage and Gleason score (p = 0.043, HR = 2.61). We further performed bisulfite genomic sequencing on 2 relatively unknown genes to demonstrate robustness of the assay results. PHYMA is thus a signature with high sensitivity and specificity for discriminating tumors from BPH, and has a potential role in early detection and in predicting survival.

Predictive factors of oncologic outcomes in patients who do not achieve undetectable prostate specific antigen after radical prostatectomy

PURPOSE

We identified factors predicting oncologic outcomes in cases of persistently detectable prostate specific antigen.

MATERIALS AND METHODS

We reviewed the charts of patients treated with radical prostatectomy between 1998 and 2011 at a total of 14 centers. Study inclusion criteria were radical prostatectomy for presumed localized prostate cancer, absent positive nodes and detectable prostate specific antigen, defined as prostate specific antigen 0.1 ng/ml or greater 6 weeks postoperatively. Of the 9,735 radical prostatectomy cases reviewed 496 (5.1%) were eligible for analysis. Predictive factors for oncologic outcomes were assessed in time dependent analyses using the Kaplan-Meier method and Cox regression models.

RESULTS

At 6 weeks prostate specific antigen was 0.1 to 6.8 ng/ml. Biochemical progression was noted in 74.4% of patients and clinical metastasis was noted in 5%. The 2 most powerful predictors of general salvage treatment (vs radiotherapy) were postoperative prostate specific antigen greater than 1 ng/ml (OR 3.46, p=0.032) and prostate specific antigen velocity greater than 0.2 ng/ml per year (HR 6.01, p=0.001). Positive prostate specific antigen velocity was the single factor that independently correlated with the risk of failed salvage therapy (HR 2.6, p=0.001). The 5-year disease-free survival rate was 81.0% in patients with stable or negative prostate specific antigen velocity compared with 58.4% in those with positive prostate specific antigen velocity (p<0.001).

CONCLUSIONS

Patients with detectable prostate specific antigen after radical prostatectomy have a poor biochemical outcome. We identified postoperative prostate specific antigen and prostate specific antigen velocity as independent predictors of progression and failed salvage treatment. In addition to pathological prognostic factors, these factors should be considered early to better stratify patients for adjuvant therapy.

Tumor-associated copy number changes in the circulation of patients with prostate cancer identified through whole-genome sequencing

BACKGROUND

Patients with prostate cancer may present with metastatic or recurrent disease despite initial curative treatment. The propensity of metastatic prostate cancer to spread to the bone has limited repeated sampling of tumor deposits. Hence, considerably less is understood about this lethal metastatic disease, as it is not commonly studied. Here we explored whole-genome sequencing of plasma DNA to scan the tumor genomes of these patients non-invasively.

METHODS

We wanted to make whole-genome analysis from plasma DNA amenable to clinical routine applications and developed an approach based on a benchtop high-throughput platform, that is, Illuminas MiSeq instrument. We performed whole-genome sequencing from plasma at a shallow sequencing depth to establish a genome-wide copy number profile of the tumor at low costs within 2 days. In parallel, we sequenced a panel of 55 high-interest genes and 38 introns with frequent fusion breakpoints such as the TMPRSS2-ERG fusion with high coverage. After intensive testing of our approach with samples from 25 individuals without cancer we analyzed 13 plasma samples derived from five patients with castration resistant (CRPC) and four patients with castration sensitive prostate cancer (CSPC).

RESULTS

The genome-wide profiling in the plasma of our patients revealed multiple copy number aberrations including those previously reported in prostate tumors, such as losses in 8p and gains in 8q. High-level copy number gains in the AR locus were observed in patients with CRPC but not with CSPC disease. We identified the TMPRSS2-ERG rearrangement associated 3-Mbp deletion on chromosome 21 and found corresponding fusion plasma fragments in these cases. In an index case multiregional sequencing of the primary tumor identified different copy number changes in each sector, suggesting multifocal disease. Our plasma analyses of this index case, performed 13 years after resection of the primary tumor, revealed novel chromosomal rearrangements, which were stable in serial plasma analyses over a 9-month period, which is consistent with the presence of one metastatic clone.

CONCLUSIONS

The genomic landscape of prostate cancer can be established by non-invasive means from plasma DNA. Our approach provides specific genomic signatures within 2 days which may therefore serve as 'liquid biopsy'.

Serum sarcosine increases the accuracy of prostate cancer detection in patients with total serum PSA less than 4.0 ng/ml

BACKGROUND

Sarcosine is reported to be a differential metabolite that is greatly increased during prostate cancer (PCa) progression. In this study, we assessed the role of serum sarcosine as a biomarker for PCa, as well as any association between sarcosine levels and clinical-pathological parameters.

METHODS

Sarcosine was measured by fluorometric assay in serum samples from 290 PCa patients and 312 patients with no evidence of malignancy (NEM), confirmed by 8-12 core prostate biopsies. Nonparametric statistical tests and receiver operating characteristics (ROC) analyses were performed to assess the diagnostic performance of sarcosine in different (prostate-specific antigen) PSA ranges.

RESULTS

ROC analyses in subjects with PSA < 4 ng/ml showed a higher predictive value of sarcosine (AUC = 0.668) versus total PSA (AUC = 0.535) (P = 0.03), whereas for the other two PSA ranges (4-10 ng/ml and >10 ng/ml), percent ratio of free to total PSA (%fPSA) showed a predictive superiority over sarcosine. Moreover, in patients with a PSA < 4 ng/ml, the percentage of low/intermediate-grade cancers was positively associated with sarcosine levels (P = 0.005). The specificities for serum sarcosine, %fPSA, PSA, and the logistic regression model at 95% sensitivity were 24.4, 3.41, 2.22, and 28.4%, respectively.

CONCLUSIONS

We provide evidence that serum sarcosine has a higher predictive value than tPSA and %fPSA in patients with PSA < 4 ng/ml. Moreover, sarcosine levels were significantly different in low grade versus high grade cancers in this subset of patients, suggesting that this marker may be a further tool not only for diagnosing PCa in normal PSA and abnormal DRE/TRUS patients but also for selecting candidates for non-aggressive therapies and active surveillance.

Plasma-derived exosomal survivin, a plausible biomarker for early detection of prostate cancer

Background

Survivin is expressed in prostate cancer (PCa), and its downregulation sensitizes PCa cells to chemotherapeutic agents in vitro and in vivo. Small membrane-bound vesicles called exosomes, secreted from the endosomal membrane compartment, contain RNA and protein that they readily transport via exosome internalization into recipient cells. Recent progress has shown that tumor-derived exosomes play multiple roles in tumor growth and metastasis and may produce these functions via immune escape, tumor invasion and angiogenesis. Furthermore, exosome analysis may provide novel biomarkers to diagnose or monitor PCa treatment.

Methods

Exosomes were purified from the plasma and serum from 39 PCa patients, 20 BPH patients, 8 prostate cancer recurrent and 16 healthy controls using ultracentrifugation and their quantities and qualities were quantified and visualized from both the plasma and the purified exosomes using ELISA and Western blotting, respectively.

Results

Survivin was significantly increased in the tumor-derived samples, compared to those from BPH and controls with virtually no difference in the quantity of Survivin detected in exosomes collected from newly diagnosed patients exhibiting low (six) or high (nine) Gleason scores. Exosome Survivin levels were also higher in patients that had relapsed on chemotherapy compared to controls.

Conclusions

These studies demonstrate that Survivin exists in plasma exosomes from both normal, BPH and PCa subjects. The relative amounts of exosomal Survivin in PCa plasma was significantly higher than in those with pre-inflammatory BPH and control plasma. This differential expression of exosomal Survivin was seen with both newly diagnosed and advanced PCa subjects with high or low-grade cancers. Analysis of plasma exosomal Survivin levels may offer a convenient tool for diagnosing or monitoring PCa and may, as it is elevated in low as well as high Gleason scored samples, be used for early detection.

Prognostic value of blood mRNA expression signatures in castration-resistant prostate cancer: a prospective, two-stage study

BACKGROUND

Biomarkers are urgently needed to dissect the heterogeneity of prostate cancer between patients to improve treatment and accelerate drug development. We analysed blood mRNA expression arrays to identify patients with metastatic castration-resistant prostate cancer with poorer outcome.

METHODS

Whole blood was collected into PAXgene tubes from patients with castration-resistant prostate cancer and patients with prostate cancer selected for active surveillance. In stage I (derivation set), patients with castration-resistant prostate cancer were used as cases and patients under active surveillance were used as controls. These patients were recruited from The Royal Marsden Hospital NHS Foundation Trust (Sutton, UK) and The Beatson West of Scotland Cancer Centre (Glasgow, UK). In stage II (validation-set), patients with castration-resistant prostate cancer recruited from the Memorial Sloan-Kettering Cancer Center (New York, USA) were assessed. Whole-blood RNA was hybridised to Affymetrix U133plus2 microarrays. Expression profiles were analysed with Bayesian latent process decomposition (LPD) to identify RNA expression profiles associated with castration-resistant prostate cancer subgroups; these profiles were then confirmed by quantative reverse transcriptase (qRT) PCR studies and correlated with overall survival in both the test-set and validation-set.

FINDINGS

LPD analyses of the mRNA expression data divided the evaluable patients in stage I (n=94) into four groups. All patients in LPD1 (14 of 14) and most in LPD2 (17 of 18) had castration-resistant prostate cancer. Patients with castration-resistant prostate cancer and those under active surveillance comprised LPD3 (15 of 31 castration-resistant prostate cancer) and LDP4 (12 of 21 castration-resistant prostate cancer). Patients with castration-resistant prostate cancer in the LPD1 subgroup had features associated with worse prognosis and poorer overall survival than patients with castration-resistant prostate cancer in other LPD subgroups (LPD1 overall survival 10·7 months [95% CI 4·1-17·2] vs non-LPD1 25·6 months [18·0-33·4]; p<0·0001). A nine-gene signature verified by qRT-PCR classified patients into this LPD1 subgroup with a very low percentage of misclassification (1·2%). The ten patients who were initially unclassifiable by the LPD analyses were subclassified by this signature. We confirmed the prognostic utility of this nine-gene signature in the validation castration-resistant prostate cancer cohort, where LPD1 membership was also associated with worse overall survival (LPD1 9·2 months [95% CI 2·1-16·4] vs non-LPD1 21·6 months [7·5-35·6]; p=0·001), and remained an independent prognostic factor in multivariable analyses for both cohorts.

INTERPRETATION

Our results suggest that whole-blood gene profiling could identify gene-expression signatures that stratify patients with castration-resistant prostate cancer into distinct prognostic groups.

FUNDING

AstraZeneca, Experimental Cancer Medicine Centre, Prostate Cancer Charity, Prostate Cancer Foundation.

Quantitative RT-PCR analysis of PSA and prostate-specific membrane antigen mRNA to detect circulating tumor cells improves recurrence-free survival nomogram prediction after radical prostatectomy

BACKGROUND

Circulating tumor cell (CTC) analysis is a potential new biomarker in prostate cancer. We hypothesize that quantitative detection of CTCs in patients pre- and post-radical prostatectomy (RP) using quantitative TaqMan® fluorogenic RT-PCR will improve the accuracy of the Kattan nomogram to predict the probability of recurrence-free survival (RFS) post-RP.

METHODS

Ninty-two patients who underwent RP between 2004 and 2009 had venous blood samples taken pre- (Day - 1) and post-operatively (Day + 7). We performed quantitative Taqman® RT-PCR to detect circulating prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) mRNA. We calculated both the logarithmic ratio of Day + 7/Day - 1 for PSA (PSAr) and PSMA (PSMAr) expression (log(Day+7/Day-1) ) and the Kattan nomogram predicted probability of disease recurrence for each patient. We then analyzed how the AUC-ROC analysis for the Kattan nomogram prediction alone (K) compared to the addition of the PSAr and PSMAr in predicting 5-year RFS.

RESULTS

The mean age (years), PSA (ng/ml), and follow-up (mo) was 65.1, 9.13, and 72, respectively. The AUCs for K, PSAr + K, and PSMAr + K were 0.752 (95%CI 0.620-0.860), 0.830 (95%CI 0.740-0.911), and 0.837 (95%CI 0.613-0.923), respectively (P = 0.03). The Kattan 5-year PSA RFS was 75%. The actual 5-year PSA RFS survival rate was 77%.

CONCLUSIONS

Data from modern quantitative RT-PCR to detect circulating prostate-derived PSA and PSM mRNA pre- and post-RP improves the accuracy of the Kattan nomogram to predict biochemical recurrence.

The role of combined measurement of tissue mRNA levels of AMACR and survivin in the diagnosis and risk stratification of patients with suspected prostate cancer

AIM

To determine whether the measurement of tissue mRNA levels of AMACR and survivin has a role in distinguishing prostate cancer (PCa) from benign lesions and high risk from low-risk PCa in men with suspected PCa.

METHODS

TRUS prostate biopsies from 170 patients with suspected PCa were used to measure the mRNA levels of AMACR and survivin using semi-quantitative RT-PCR technique. The diagnosis, staging and risk stratification of PCa was based on established clinical criteria. The ability of tissue mRNA levels to distinguish benign from malignant prostate and high- and low-risk PCa was assessed. The diagnostic value for the two genes was evaluated by calculating their individual and combined sensitivity and specificity, which were compared with that of PSA.

RESULTS

Histological examination showed 90/170 (53%) of patients had benign prostate pathology, while 80/170 (47%) had PCa. Tissue mRNA levels of both AMACR and survivin were able to distinguish benign from PCa biopsies (p<0.0001) and also high-risk from low-risk PCa cases (p<0.02, p<0.05, respectively). Compared with serum PSA levels, the combined use of tissue mRNA levels of AMACR and survivin yielded a higher detection specificity (84 vs. 22%).

CONCLUSION

Based on AMACR and survivin combined sensitivity and specificity, these mRNA markers can be used as an adjunct to distinguish patients with and without PCa and in men with PCa may help to identify those with low- or high-risk PCa.

L-dopa decarboxylase (DDC) gene expression is related to outcome in patients with prostate cancer

What's known on the subject? and What does the study add? L-dopa decarboxylase (DDC) has been documented as a novel co-activator of androgen receptor transcriptional activity. Recently, it was shown that DDC gene expression is significantly higher in patients with PCa than in those with BPH. In the present study, there was a significant association between the DDC gene expression levels and the pathological stage and Gleason score of patients with prostate cancer (PCa). Moreover, DDC expression was shown to be an unfavourable prognostic marker of biochemical recurrence and disease-free survival in patients with PCa treated by radical prostatectomy.

OBJECTIVE

To determine whether L-dopa decarboxylase gene (DDC) expression levels in patients with prostate cancer (PCa) correlate to biochemical recurrence and disease prognosis after radical prostatectomy (RP).

PATIENTS AND METHODS

The present study consisted of 56 samples with confirmed malignancy from patients with PCa who had undergone RP at a single tertiary academic centre. Total RNA was isolated from tissue specimens and a SYBR Green fluorescence-based quantitative real-time polymerase chain reaction methodology was developed for the determination of DDC mRNA expression levels of the tested tissues. Follow-up time ranged between 1.0 and 62.0 months (mean ± SE, 28.6 ± 2.1 month; median, 31.5 months). Time to biochemical recurrence was defined as the interval between the surgery and the measurement of two consecutive values of prostate-specific antigen (PSA) ≥0.2 ng/mL.

RESULTS

DDC expression levels were found to be positively correlated with the tumour-node-metastasis stage (P = 0.021) and Gleason score (P = 0.036) of the patients with PCa. Patients with PCa with raised DDC expression levels run a significantly higher risk of biochemical recurrence after RP, as indicated by Cox proportional regression analysis (P = 0.021). Multivariate Cox proportional regression models revealed the preoperative PSA-, age- and digital rectal examination-independent prognostic value of DDC expression for the prediction of disease-free survival (DFS) among patients with PCa (P = 0.036). Kaplan-Meier survival analysis confirms the significantly shorter DFS after RP of PCa with higher DDC expression levels (P = 0.015).

CONCLUSIONS

This is the first study indicating the potential of DDC expression as a novel prognostic biomarker in patients with PCa who have undergone RP. For further evaluation and clinical application of the findings of the present study, a direct analysis of mRNA and/or its protein expression level in preoperative biopsy, blood serum and urine should be conducted.

Assessing the risk of lymph node invasion in patients with intermediate risk prostate cancer treated with extended pelvic lymph node dissection. A novel prediction tool

BACKGROUND

Controversy exists regarding the need for extended pelvic lymph node dissection (ePLND) in patients with intermediate risk prostate cancer (PCa).

MATERIALS AND METHODS

The study included 982 consecutive men with intermediate risk PCa (PSA 10–20 ng/ml or cT2b-c or biopsy Gleason 3 + 4/ 4 + 3) treated with ePLND and radical prostatectomy (RP) at a single center. All patients underwent an anatomically defined ePLND. A novel risk stratification tool was developed by applying the nonparametric tree modeling technique of classification and regression tree analysis (CART) which relied on pre-operative PSA, clinical stage, biopsy Gleason score, and percentage of positive cores. The area under the receiver characteristic curve (AUC) method was used to quantify the accuracy of the model.

RESULTS

Lymph node invasion (LNI) was found in 81 (8.2%) patients. The CART analyses identified three risk groups of having LNI: a) Low risk: Gleason 3 + 3, cT1c/cT2, PSA 10-20 ng/ml, or Gleason 3 + 4/4 + 3, ≤ 63% of positive cores and PSA < 5 ng/ml (risk of LNI:3.7 and 5.2%, respectively; 64.8% of patients included); b) Moderate risk: Gleason 3 + 4/4 + 3, ≤ 63% of positive cores and PSA ≥ 5 ng/ml (risk of LNI:14.4%; 23% of patients included); c)High risk: Gleason 3 + 4/4 + 3, % positive cores >63% (risk of LNI:20.1%; 12.% of patients included; P < 0.001). The accuracy of the model was 71%.

CONCLUSIONS

The risk of having LNI varies significantly (3.7–20.1%) in patients with intermediate risk PCa. Our predictive tool might help selecting those patients suitable fore PLND, allowing to spare this approach in about 60% of intermediate risk patients.

Serum/glucocorticoid-regulated kinase 1 expression in primary human prostate cancers

BACKGROUND

Serum/glucocorticoid-regulated kinase 1 (SGK1), a known target of the androgen receptor (AR) and glucocorticoid receptor (GR), is reported to enhance cell survival. This study sought to better define the role of SGK1 and GR in prostate cancer.

METHODS

Immunohistochemistry was performed for AR, GR, and SGK1 on primary prostate cancers (n = 138) and 18 prostate cancers from patients treated with androgen deprivation therapy. Relative staining intensity was compared utilizing a Fisher's exact test. Univariate analyses were performed using log-rank and chi-squared tests to evaluate prostate cancer recurrence with respect to SGK1 expression.

RESULTS

SGK1 expression was strong (3+) in 79% of untreated cancers versus 44% in androgen-deprived cancers (P = 0.003). Conversely, GR expression was present in a higher proportion of androgen-deprived versus untreated cancers (78% vs. 38%, P = 0.002). High-grade cancers were nearly twice as likely to have relatively low (0 to 2+) SGK1 staining compared to low-grade cancers (13.8% vs. 26.5%, P = 0.08). Low SGK1 expression in untreated tumors was associated with increased risk of cancer recurrence (adjusted log-rank test P = 0.077), 5-year progression-free survival 47.8% versus 72.6% (P = 0.034).

CONCLUSIONS

SGK1 expression is high in most untreated prostate cancers and declines with androgen deprivation. However, these data suggest that relatively low expression of SGK1 is associated with higher tumor grade and increased cancer recurrence, and is a potential indicator of aberrant AR signaling in these tumors. GR expression increased with androgen deprivation, potentially providing a mechanism for the maintenance of androgen pathway signaling in these tumors. Further study of the AR/GR/SGK1 network in castration resistance.

Assessing prostate cancer growth with citrate measured by intact tissue proton magnetic resonance spectroscopy

BACKGROUND

Annual PSA tests have led to a significant increase in the number of prostate cancer (PCa) cases diagnosed. This increased incidence has led to overtreatment of many patients, as current pathology often cannot distinguish latent from aggressive PCa. Studies have shown that the depletion of zinc in prostate cells correlated with cell-line growth rates, and may therefore relate to the progression of PCa. Furthermore, as zinc is normally an inhibitor of citrate oxidation, the reduction of zinc in PCa may cause a decrease in citrate secretion levels in the glandular epithelia of PCa patients.

METHODS

Using high-resolution magic angle spinning proton magnetic resonance spectroscopy followed by quantitative histopathology, we investigate unit histo-benign prostate epithelial citrate concentrations in intact tissue samples obtained from 18 patients with pre-surgical PSA values less than 20 ng/ml. Using these data, we evaluate correlations between citrate concentrations and PSA velocities, densities and blood percent-free PSA.

RESULTS

We observe different linear patterns between citrate concentrations and histo-benign glandular epithelia from patients of different PSA velocities. More importantly, we obtain a significant correlation between PSA velocity, density and percent-free PSA, and citrate concentrations in unit volume of histo-benign epithelial glands of the peripheral zone.

CONCLUSIONS

Low levels of citrate in unit volume represent rapidly increasing PSA values, and, therefore, may be used as an indicator of fast-growing PCa. Thus, tissue samples obtained at the time of biopsy may be evaluated for their citrate concentrations for the prediction of PCa growth rates, allowing for the implementation of alternative treatment options and reducing overtreatment.

Tissue and serum mesothelin are potential markers of neoplastic progression in Barrett's associated esophageal adenocarcinoma

BACKGROUND

Mesothelin is overexpressed in several malignancies and is purportedly a specific marker of malignant transformation. In this pilot study, we investigated whether tissue and serum mesothelin are potential markers of neoplastic progression in Barrett's esophagus (BE) and in esophageal adenocarcinoma (EAC).

METHODS

Mesothelin expression was retrospectively evaluated in normal, BE, and EAC tissue from surgically resected esophageal specimens (n = 125). In addition, soluble mesothelin-related peptide (SMRP) levels were measured in serum.

RESULTS

Normal esophageal mucosa did not express mesothelin. BE tissue with high-grade dysplasia specifically expressed mesothelin, whereas BE tissue with low-grade or without dysplasia did not. Fifty-seven (46%) EAC tumors were positive for mesothelin. EAC tumors with BE expressed mesothelin more often than those without BE (58% vs. 35%, P = 0.01). SMRP levels were elevated in 70% of EAC patients (mean = 0.89 nmol/L; range: 0.03-3.77 nmol/L), but not in patients with acid reflux and/or BE.

CONCLUSIONS

Mesothelin is commonly expressed in BE-associated EAC. On the basis of this pilot study, a prospective study is under way to evaluate tissue and serum mesothelin which are potential markers of neoplastic progression in BE and in EAC (NCT01393483).

IMPACT

Current surveillance methods in Barrett's esophagus are invasive and neither cost-effective nor sensitive. This pilot study suggests that serum mesothelin is a marker of neoplastic transformation in BE and may provide a noninvasive method to improve identification of malignant transformation.

A patient with prostate cancer and multiple myeloma-diagnostics and possible association of both diseases

In this report, we describe a case of a patient with prostate cancer and multiple myeloma as the second metachronous malignant disease. To our knowledge, synchronous occurrence of bone marrow prostate cancer metastases and multiple myeloma-as it was found in the clinical disease course of our patient-has not been documented in the literature. Among other diagnostic procedures, cytomorphology and immunocytochemistry analyses contribute to detection of metastases of epithelial cells and synchronous plasma cell proliferation in bone marrow. Occurrence of multiple myeloma and prostate cancer in our patient adds to other similar reports and points to possible association between both diseases and also to other factors involved in the development of a second malignant disease. Further studies are needed to confirm and clarify this association, because prostate cancer is a relatively common malignant disease.

A tri-marker proliferation index predicts biochemical recurrence after surgery for prostate cancer

Prostate cancer exhibits tremendous variability in clinical behavior, ranging from indolent to lethal disease. Better prognostic markers are needed to stratify patients for appropriately aggressive therapy. By expression profiling, we can identify a proliferation signature variably expressed in prostate cancers. Here, we asked whether one or more tissue biomarkers might capture that information, and provide prognostic utility. We assayed three proliferation signature genes: MKI67 (Ki-67; also a classic proliferation biomarker), TOP2A (DNA topoisomerase II, alpha), and E2F1 (E2F transcription factor 1). Immunohistochemical staining was evaluable on 139 radical prostatectomy cases (in tissue microarray format), with a median clinical follow-up of eight years. Each of the three proliferation markers was by itself prognostic. Notably, combining the three markers together as a “proliferation index” (0 or 1, vs. 2 or 3 positive markers) provided superior prognostic performance (hazard ratio = 2.6 (95% CI: 1.4–4.9); P = 0.001). In a multivariate analysis that included preoperative serum prostate specific antigen (PSA) levels, Gleason grade and pathologic tumor stage, the composite proliferation index remained a significant predictor (P = 0.005). Analysis of receiver-operating characteristic (ROC) curves confirmed the improved prognostication afforded by incorporating the proliferation index (compared to the clinicopathologic data alone). Our findings highlight the potential value of a multi-gene signature-based diagnostic, and define a tri-marker proliferation index with possible utility for improved prognostication and treatment stratification in prostate cancer.

Evaluation of the prognostic significance of MSMB and CRISP3 in prostate cancer using automated image analysis

Despite prostate cancer being the most frequent cancer in men in the Western world, tissue biomarkers for predicting disease recurrence after surgery have not been incorporated into clinical practice. Our group has previously identified β-microseminoprotein (MSMB) and cysteine-rich secretory protein-3 (CRISP3) as independent predictors of biochemical recurrence after radical prostatectomy. The purpose of the present study was to use automated image analysis, enabling quantitative determination of MSMB and CRISP3 expressions in a large cohort and to validate the previous findings. MSMB and CRISP3 protein expressions were assessed on tissue microarrays constructed from 3268 radical prostatectomy specimens. Whole-slide digital images were captured, and a novel cytoplasmic algorithm was used to develop a quantitative scoring model for cytoplasmic staining. Classification regression tree analysis was used to group patients, with different risk for biochemical recurrence, depending on level of protein expression. Patients with tumors expressing high levels of MSMB had a significantly reduced risk for biochemical recurrence after radical prostatectomy (HR=0.468; 95% CI 0.394-0.556; P<0.001). Multivariate analysis adjusted for clinicopathological parameters revealed that MSMB expression was an independent predictor of decreased risk of recurrence (HR=0.710; 95% CI 0.578-0.872; P<0.001). We found no correlation between CRISP3 expression and biochemical recurrence. In this current study, we applied a novel image analysis on a large independent cohort and successfully verified that MSMB is a strong independent factor, predicting favorable outcome after radical prostatectomy for localized prostate cancer.

Diagnostic biomarkers of prostate cancer

OBJECTIVE

Diagnostic tissue biomarkers for prostate cancer (PC) include basal cell markers and α-methylacyl-coenzyme A-racemase (AMACR), often used in combination. Their sensitivity and specificity are not perfect and there is a need for additional diagnostic biomarkers for PC in cases that are difficult to diagnose on routine stained sections.

MATERIAL AND METHODS

This study investigated the diagnostic accuracy of three novel tissue biomarkers for PC found through a search in the Human Protein Atlas database ( www.proteinatlas.com ): somatic cytochrome c (CYCS), intestinal cell kinase (ICK) and inhibitor of nuclear factor-κB kinase subunit beta (IKBKB), and compared the results with AMACR. A tissue microarray was constructed from 40 consecutive radical prostatectomy (RP) specimens including benign prostatic tissue, atrophy, high-grade prostatic intraepithelial neoplasia (HGPIN) and PC. Immunoreactivity was scored based on staining intensity and extent. Real-time polymerase chain reaction (PCR) was performed on malignant and benign frozen tissue samples from 32 RP specimens.

RESULTS

All four biomarkers showed a stronger expression in PC and HGPIN than in benign tissue (p < 0.001). The highest diagnostic accuracy for PC was achieved with ICK and AMACR at 97%. The area under the curve for CYCS, ICK, IKBKB and AMACR was 0.859, 0.997, 0.865 and 0.983, respectively. The presence of mRNA transcripts of the genes was confirmed by real-time PCR in benign and malignant prostatic tissue.

CONCLUSIONS

AMACR is an accurate diagnostic tissue marker for PC. However, in some PCs AMACR is false negative and a panel of CYCS, ICK and IKBKB may serve as ancillary diagnostic tool.

Being more realistic about the public health impact of genomic medicine

Wayne Hall and colleagues discuss the limitations of genomic risk prediction for population-level preventive health care.