Frank Smit

Detection of TMPRSS2-ERG Fusion Transcripts and Prostate Cancer Antigen 3 in Urinary Sediments May Improve Diagnosis of Prostate Cancer

Purpose: Early detection of prostate cancer can increase the curative success rate for prostate cancer. We studied the diagnostic usefulness of TMPRSS2-ERG fusion transcripts as well as the combination of prostate cancer antigen 3 (PCA3) RNA and TMPRSS2-ERG fusion transcripts in urinary sediments after digital rectal examination (DRE). Experimental Design: A total of 78 men with prostate cancer–positive biopsies and 30 men with prostate cancer–negative biopsies were included in this study. After DRE, the first voided urine was collected, and urinary sediments were obtained. We used semiquantitative reverse transcription-PCR (RT-PCR) analysis followed by Southern blot hybridization with a radiolabeled probe for the detection TMPRSS2-ERG fusion transcripts in these urinary sediments. A quantitative RT-PCR assay for PCA3 was used to determine the PCA3 score in the same sediments. Results: TMPRSS2-ERG fusion transcripts can be detected in the urine after DRE with a sensitivity of 37%. In this cohort of patients, the PCA3-based assay had a sensitivity of 62%. When both markers were combined, the sensitivity increased to 73%. Especially in the cohort of men with persistently elevated serum prostate-specific antigen levels and history of negative biopsies, the high positive predictive value of 94% of TMPRSS2-ERG fusion transcripts could give a better indication which patients require repeat biopsies. Conclusion: In this report, we used for the first time the combination of the prostate cancer–specific biomarkers TMPRSS2-ERG and PCA3, which significantly improves the sensitivity for prostate cancer diagnosis.

TMPRSS2 Fusions with Oncogenic ETS Factors in Prostate Cancer Involve Unbalanced Genomic Rearrangements and Are Associated with HDAC1 and Epigenetic Reprogramming

Translocations fusing the strong androgen-responsive gene, TMPRSS2, with ERG or other oncogenic ETS factors may facilitate prostate cancer development. Here, we studied 18 advanced prostate cancers for ETS factor alterations, using reverse transcription-PCR and DNA and RNA array technologies, and identified putative ERG downstream gene targets from the microarray data of 410 prostate samples. Out of the 27 ETS factors, ERG was most frequently overexpressed. Seven cases showed TMPRSS2:ERG gene fusions, whereas the TMPRSS2:ETV4 fusion was seen in one case. In five out of six tumors with high ERG expression, array-CGH analysis revealed interstitial 2.8 Mb deletions between the TMPRSS2 and ERG loci, or smaller, unbalanced rearrangements. In silico analysis of the ERG gene coexpression patterns revealed an association with high expression of the histone deacetylase 1 gene, and low expression of its target genes. Furthermore, we observed increased expression of WNT-associated pathways and down-regulation of tumor necrosis factor and cell death pathways. In summary, our data indicate that the TMPRSS2:ERG translocation is common in advanced prostate cancer and occurs by virtue of unbalanced genomic rearrangements. Activation of ERG by fusion with TMPRSS2 may lead to epigenetic reprogramming, WNT signaling, and down-regulation of cell death pathways, implicating ERG in several hallmarks of cancer with potential therapeutic importance.

Prospective Multicentre Evaluation of PCA3 and TMPRSS2-ERG Gene Fusions as Diagnostic and Prognostic Urinary Biomarkers for Prostate Cancer ☆

BACKGROUND Prostate cancer antigen 3 (PCA3) and v-ets erythroblastosis virus E26 oncogene homolog (TMPRSS2-ERG) gene fusions are promising prostate cancer (PCa) specific biomarkers that can be measured in urine. OBJECTIVE To evaluate the diagnostic and prognostic value of Progensa PCA3 and TMPRSS2-ERG gene fusions (as individual biomarkers and as a panel) for PCa in a prospective multicentre setting. DESIGN, SETTING, AND PARTICIPANTS At six centres, post-digital rectal examination first-catch urine specimens prior to prostate biopsies were prospectively collected from 497 men. We assessed the predictive value of Progensa PCA3 and TMPRSS2-ERG (quantitative nucleic acid amplification assay to detect TMPRSS2-ERG messenger RNA [mRNA]) for PCa, Gleason score, clinical tumour stage, and PCa significance (individually and as a marker panel). This was compared with serum prostate-specific antigen and the European Randomised Study of Screening for Prostate Cancer (ERSPC) risk calculator. In a subgroup (n=61) we evaluated biomarker association with prostatectomy outcome. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Univariate and multivariate logistic regression analysis and receiver operating curves were used. RESULTS AND LIMITATIONS Urine samples of 443 men contained sufficient mRNA for marker analysis. PCa was diagnosed in 196 of 443 men. Both PCA3 and TMPRSS2-ERG had significant additional predictive value to the ERSPC risk calculator parameters in multivariate analysis (p<0.001 and resp. p=0.002). The area under the curve (AUC) increased from 0.799 (ERSPC risk calculator), to 0.833 (ERSPC risk calculator plus PCA3), to 0.842 (ERSPC risk calculator plus PCA3 plus TMPRSS2-ERG) to predict PCa. Sensitivity of PCA3 increased from 68% to 76% when combined with TMPRSS2-ERG. TMPRSS2-ERG added significant predictive value to the ERSPC risk calculator to predict biopsy Gleason score (p<0.001) and clinical tumour stage (p=0.023), whereas PCA3 did not. CONCLUSIONS TMPRSS2-ERG had independent additional predictive value to PCA3 and the ERSPC risk calculator parameters for predicting PCa. TMPRSS2-ERG had prognostic value, whereas PCA3 did not. Implementing the novel urinary biomarker panel PCA3 and TMPRSS2-ERG into clinical practice would lead to a considerable reduction of the number of prostate biopsies.

Steroidogenic enzymes and stem cell markers are upregulated during androgen deprivation in prostate cancer

Considerable levels of testosterone and dihydrotestosterone (DHT) are found In prostate cancer (PCa) tissue after androgen deprivation therapy. Treatment of surviving cancer-initiating cells and the ability to metabolize steroids from precursors may be the keystones for the appearance of recurrent tumors. To study this hypothesis, we assessed the expression of several steroidogenic enzymes and stem cell markers in clinical PCa samples and cell cultures during androgen depletion. Gene expression profiles were determined by microarray or qRT-PCR. In addition, we measured cell viability and analyzed stem cell marker expression in DuCaP cells by immunocytochemistry. Seventy patient samples from different stages of PCa, and the PCa cell line DuCaP were included in this study. The androgen receptor (AR) and enzymes (AKR1C3, HSD17B2, HSD17B3, UGT2B15 and UGT2B17) that are involved in the metabolism of adrenal steroids were upregulated in castration resistant prostate cancer (CRPC). In vitro, some DuCaP cells survived androgen depletion, and eventually gave rise to a culture adapted to these conditions. During and after this transition, most of the steroidogenic enzymes were upregulated. These cells also are enriched with stem/progenitor cell markers cytokeratin 5 (CK5) and ATP-binding cassette sub-family G member 2 (ABCG2). Similarly, putative stem/progenitor cell markers CK5, c-Kit, nestin, CD44, c-met ALDH1A1, α2-integrin, CD133, ABCG2, CXCR4 and POU5F1 were upregulated in clinical CRPC. The upregulation of steroidogenic enzymes and stem cell markers in recurrent tumors suggests that cancer initiating cells can expand by adaptation to their T/DHT deprived environment. Therapies targeting the metabolism of adrenal steroids by the tumor may prove effective in preventing tumor regrowth.

Prostate Cancer Biomarker Profiles in Urinary Sediments and Exosomes

PURPOSE Urinary biomarker tests for diagnosing prostate cancer have gained considerable interest. Urine is a complex mixture that can be subfractionated. We evaluated 2 urinary fractions that contain nucleic acids, ie cell pellets and exosomes. The influence of digital rectal examination before urine collection was also studied and the prostate cancer specific biomarkers PCA3 and TMPRSS2-ERG were assayed. MATERIALS AND METHODS Urine samples were prospectively obtained before and after digital rectal examination from 30 men scheduled for prostate biopsy. Cell pellet and exosomes were isolated and used for biomarker analysis. Analytical and diagnostic performance was tested using the Student t-test and ROC curves. RESULTS Unlike the exosome fraction, urinary sediment gene expression analysis was compromised by amorphous precipitation in 10% of all specimens. Digital rectal examination resulted in increased mRNA levels in each fraction. This was particularly relevant for the exosomal fraction since after digital rectal examination the number of samples decreased in which cancer specific markers were below the analytical detection limit. Biomarker diagnostic performance was comparable to that in large clinical studies. In exosomes the biomarkers had to be normalized for prostate specific antigen mRNA while cell pellet absolute PCA3 levels had diagnostic value. CONCLUSIONS Exosomes have characteristics that enable them to serve as a stable substrate for biomarker analysis. Thus, digital rectal examination enhances the analytical performance of biomarker analysis in exosomes and cell pellets. The diagnostic performance of biomarkers in exosomes differs from that of cell pellets. Clinical usefulness must be prospectively assessed in larger clinical cohorts.

Arachidonic Acid Pathway Members PLA2G7, HPGD, EPHX2, and CYP4F8 Identified as Putative Novel Therapeutic Targets in Prostate Cancer

The arachidonic acid and prostaglandin pathway has been implicated in prostate carcinogenesis, but comprehensive studies of the individual members in this key pathway are lacking. Here, we first conducted a systematic bioinformatic study of the expression of 36 arachidonic acid pathway genes across 9783 human tissue samples. The results showed that the PLA2G7, HPGD, EPHX2, and CYP4F8 genes are highly expressed in prostate cancer. Functional studies using RNA interference in prostate cancer cells indicated that all four genes are also essential for cell growth and survival. Clinical validation confirmed high PLA2G7 expression, especially in ERG oncogene-positive prostate cancers, and its silencing sensitized ERG-positive prostate cancer cells to oxidative stress. HPGD was highly expressed in androgen receptor (AR)-overexpressing advanced tumors, as well as in metastatic prostate cancers. EPHX2 mRNA correlated with AR in primary prostate cancers, and its inhibition in vitro reduced AR signaling and potentiated the effect of antiandrogen flutamide in cultured prostate cancer cells. In summary, we identified four novel putative therapeutic targets with biomarker potential for different subtypes of prostate cancer. In addition, our results indicate that inhibition of these enzymes may be particularly powerful when combined with other treatments, such as androgen deprivation or induction of oxidative stress.

Detection of High-grade Prostate Cancer Using a Urinary Molecular Biomarker-Based Risk Score.

BACKGROUND To reduce overdiagnosis and overtreatment, a test is urgently needed to detect clinically significant prostate cancer (PCa). OBJECTIVE To develop a multimodal model, incorporating previously identified messenger RNA (mRNA) biomarkers and traditional risk factors that could be used to identify patients with high-grade PCa (Gleason score ≥7) on prostate biopsy. DESIGN, SETTING, AND PARTICIPANTS In two prospective multicenter studies, urine was collected for mRNA profiling after digital rectal examination (DRE) and prior to prostate biopsy. The multimodal risk score was developed on a first cohort (n=519) and subsequently validated clinically in an independent cohort (n=386). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The mRNA levels were measured using reverse transcription quantitative polymerase chain reaction. Logistic regression was used to model patient risk and combine risk factors. Models were compared using the area under the curve (AUC) of the receiver operating characteristic, and clinical utility was evaluated with a decision curve analysis (DCA). RESULTS AND LIMITATIONS HOXC6 and DLX1 mRNA levels were shown to be good predictors for the detection of high-grade PCa. The multimodal approach reached an overall AUC of 0.90 (95% confidence interval [CI], 0.85-0.95) in the validation cohort (AUC 0.86 in the training cohort), with the mRNA signature, prostate-specific antigen (PSA) density, and previous cancer-negative prostate biopsies as the strongest, most significant components, in addition to nonsignificant model contributions of PSA, age, and family history. For another model, which included DRE as an additional risk factor, an AUC of 0.86 (95% CI, 0.80-0.92) was obtained (AUC 0.90 in the training cohort). Both models were successfully validated, with no significant change in AUC in the validation cohort, and DCA indicated a strong net benefit and the best reduction in unnecessary biopsies compared with other clinical decision-making tools, such as the Prostate Cancer Prevention Trial risk calculator and the PCA3 assay. CONCLUSIONS The risk score based on the mRNA liquid biopsy assay combined with traditional clinical risk factors identified men at risk of harboring high-grade PCa and resulted in a better patient risk stratification compared with current methods in clinical practice. Therefore, the risk score could reduce the number of unnecessary prostate biopsies. PATIENT SUMMARY This study evaluated a novel urine-based assay that could be used as a noninvasive diagnostic aid for high-grade prostate cancer (PCa). When results of this assay are combined with traditional clinical risk factors, risk stratification for high-grade PCa and biopsy decision making are improved.

Prevalence of human xenotropic murine leukemia virus-related gammaretrovirus (XMRV) in dutch prostate cancer patients†

The occurrence of the retrovirus xenotropic murine leukemia virus (MLV)‐related virus (XMRV) has been reported in prostate tissue of patients with prostate cancer (PrCa). Considering the potential great medical and social relevance of this discovery, we investigated whether this finding could be confirmed in an independent group of Dutch sporadic PrCa cases.

Identification of a Candidate Gene Panel for the Early Diagnosis of Prostate Cancer

Purpose: Serum PSA (sPSA) testing has led to the identification of patients with indolent prostate cancer, and inevitably overtreatment has become a concern. Progensa PCA3 urine testing was shown to improve the diagnosis of prostate cancer, but its diagnostic value for aggressive prostate cancer is limited. Therefore, urinary biomarkers that can be used for prediction of Gleason score ≥7 prostate cancer in biopsies are urgently needed. Experimental Design: Using gene expression profiling data, 39 prostate cancer biomarkers were identified. After quantitative PCR analysis on tissue specimens and urinary sediments, eight promising biomarkers for the urinary detection of prostate cancer were selected (ONECUT2, HOXC4, HOXC6, DLX1, TDRD1, NKAIN1, MS4A8B, PPFIA2). The hypothesis that biomarker combinations improve the diagnostic value for aggressive prostate cancer was tested on 358 urinary sediments of an intention-to-treat cohort. Results: A urinary three-gene panel (HOXC6, TDRD1, and DLX1) had higher accuracy [area under the curve (AUC), 0.77; 95% confidence interval (CI), 0.71–0.83] to predict Gleason score ≥7 prostate cancer in biopsies compared with Progensa PCA3 (AUC, 0.68; 95% CI, 0.62–0.75) or sPSA (AUC, 0.72; 95% CI, 0.65–0.78). Combining the three-gene panel with sPSA further improved the predictive accuracy (AUC, 0.81; 95% CI, 0.75–0.86). The accuracy of the three-gene predictive model was maintained in subgroups with low sPSA concentrations. Conclusions: The urinary three-gene panel (HOXC6, TDRD1, and DLX1) represents a promising tool to identify patients with aggressive prostate cancer, also in those with low sPSA values. The combination of the urinary three-gene panel with sPSA bears great potential for the early diagnosis of patients with clinically significant prostate cancer. Clin Cancer Res; 21(13); 3061–70. ©2015 AACR.

p16 mutations/deletions are not frequent events in prostate cancer.

Cyclin-dependent kinase-4 inhibitor gene (p16INK4) has recently been mapped to chromosome 9p21. Homozygous deletions of this gene have been found at high frequency in cell lines derived from different types of tumours. These findings suggested therefore, that p16INK4 is a tumour-suppressor gene involved in a wide variety of human cancers. To investigate the frequency of p16INK mutations/deletions in prostate cancer, we screened 20 primary prostate tumours and four established cell lines by polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) analysis for exon 1 and exon 2. In contrast to most previous reports, no homozygous deletions were found in prostate cancer cell lines, but one cell line (DU145) has revealed to a mutation at codon 76. Only two SSCP shifts were detected in primary tumours: one of them corresponds to a mutation at codon 55 and the other one probably corresponds to a polymorphism. These data suggest that mutation of the p16INK4 gene is not a frequent genetic alteration implicated in prostate cancer development.