Molecular markers for prostate cancer

Proteases in cancer drug delivery

Whereas protease inhibitors have been developed successfully against hypertension and viral infections, they have failed thus far as cancer drugs. With advances in cancer profiling we now better understand that the tumor "degradome" (i.e. the repertoire of proteases and their natural inhibitors and interaction partners) forms a complex network in which specific nodes determine the global outcome of manipulation of the protease web. However, knowing which proteases are active in the tumor micro-environment, we may tackle cancers with the use of Protease-Activated Prodrugs (PAPs). Here we exemplify this concept for metallo-, cysteine and serine proteases. PAPs not only exist as small molecular adducts, containing a cleavable substrate sequence and a latent prodrug, they are presently also manufactured as various types of nanoparticles. Although the emphasis of this review is on PAPs for treatment, it is clear that protease activatable probes and nanoparticles are also powerful tools for imaging purposes, including tumor diagnosis and staging, as well as visualization of tumor imaging during microsurgical resections.

Expression of α5-integrin, α7-integrin, Ε-cadherin, and N-cadherin in localized prostate cancer

OBJECTIVE

To explore the correlation between the expression of α5-integrin, α7-integrin, Ε-cadherin, and N-cadherin in prostate cancer (PCa) and its clinicopathological data including tumor grade and clinical stage.

METHODS

The expression of α5-integrin, α7-integrin, Ε-cadherin, and N-cadherin was examined in 157 cases of PCa and adjacent normal prostatic tissue by immunohistochemical assay, and the correlation with clinicopathological features was analyzed.

RESULTS

Expressions of α5-integrin, α7-integrin, and Ε-cadherin in PCa were lower than those in normal prostatic tissues (P<0.05). N-cadherin expression was higher in cancer prostatic tissue than in normal prostatic tissues (P<0.05). The reduced expression of α5-integrin, α7-integrin, and Ε-cadherin was related to Gleason score, pathological stage, lymph node metastasis, and prostate-specific antigen level, but it was not associated with positive surgical margins and patient age. The increased expression of N-cadherin was related to Gleason score, pathological stage, lymph node metastasis, and prostate-specific antigen level, but not to age and positive surgical margins. The expression of E-cadherin was highly negatively correlated with that of N-cadherin and also positively correlated with that of α5-integrin and α7-integrin.

CONCLUSION

The reduced expression of α5-integrin, α7-integrin, and Ε-cadherin and abnormal expression of N-cadherin play an important role in the occurrence and development of PCa. The results indicate that these have potential values in the diagnosis and are predictable indices in the proliferation of PCa.

Prevalence and clinical significance of incidental (18)F-fluoro-2-deoxyglucose uptake in prostate

Purpose

To investigate the prevalence and clinical significance of incidental prostate fluoro-2-deoxyglucose (FDG) uptake and to evaluate its impact on patient management.

Materials and Methods

Of 47,109 men who underwent FDG positron emission tomography between 2004 and 2014, 1,335 (2.83%) demonstrated incidental FDG uptake in the prostate, with 99 of the latter undergoing prostate biopsy. The primary end point was the histological presence of prostate adenocarcinoma in the biopsy specimen. Outcomes, including treatment methods, survival, and causes of death, were also assessed. Factors associated with the diagnosis of prostate cancer were evaluated by using logistic regression analysis.

Results

Patients with prostate cancer were more likely to have higher serum prostate-specific antigen (PSA) (p=0.001) and focal FDG uptake (p=0.036) than were those without. Prostate cancer occurred in 1 of 26 patients (3.8%) with serum PSA<2.5 ng/mL, compared with 40 of 67 patients (59.7%) with serum PSA≥2.5 ng/mL. Multivariable analysis showed that focal lesions (odds ratio [OR], 5.50; p=0.038), age (OR, 1.06; p=0.031), and serum PSA (OR, 1.28; p=0.001) were independent predictors of prostate cancer diagnosis. Most patients with prostate cancer had organ-confined tumors. Of these, 12 (29.3%) underwent radical prostatectomy and 25 (60.9%) received hormone therapy. Of the 11 patients who died, 9 died of primary cancer progression, with only 1 patient dying from prostate cancer.

Conclusions

The prevalence of incidental FDG uptake in the prostate was not high, although patients with elevated serum PSA had a higher incidence of prostate cancer. Patients with FDG uptake in the prostate should be secondarily evaluated by measuring serum PSA, with those having high serum PSA undergoing prostate biopsy.

Quantitative assessment of the association between CYP17 rs743572 polymorphism and prostate cancer risk

Published data on the association between CYP17 rs743572 polymorphism and risk of PC showed inconclusive results. The aim of this study was to further estimate the pooled effect size of rs743572 polymorphism and PC progression via large-scale meta-analysis. We searched the case-control studies of rs743572 polymorphism and PC risk in PubMed, Embase, and Web of Science databases up to February 2014. Odds ratios (ORs) along with 95 % confidence intervals (CIs) were pooled by means of both fixed effects model and random effects model. A total of 38 publications consisting of 42 studies with 15,735 cases and 17,825 controls were included in this meta-analysis. Overall, no significant association was found between rs743572 polymorphism and PC risk. Stratified analyses by control source and sample size did not provide significant results. However, there was a borderline association in African population under A2A2 versus A1A2 + A1A1 genetic model (OR = 1.39, 95 % CI: 1.01-1.92, P = 0.975, I (2) = 0.0 %). Results from the current meta-analysis suggested that CYP17 rs743572 polymorphism might modify the risk of PC in the subjects of African decent.

Expression profile of MAGI2 gene as a novel biomarker in combination with major deregulated genes in prostate cancer

Complex molecular changes that occur during prostate cancer (PCa) progression have been described recently. Whole genome sequencing of primary PCa samples has identified recurrent gene deletions and rearrangements in PCa. Specifically, these molecular events disrupt the gene loci of phosphatase and tensin homolog (PTEN) and membrane-associated guanylate kinase inverted-2 (MAGI2). In the present study, we analyzed the expression profile of MAGI2 gene in a cohort of clinical PCa (n = 45) and benign prostatic hyperplasia (BPH) samples (n = 36) as well as three PCa cell lines. We also studied the expression of PCa-related genes, including PTEN, NKX3.1, SPINK1, DD3, AMACR, ERG, and TMPRSS2-ERG fusion in the same samples. The expression of MAGI2 mRNA was significantly down-regulated in PC3, LNCaP and DU-145 PCa cell lines (p = 0.000), and also in clinical tumor samples (Relative expression = 0.307, p = 0.002, [95 % CI 0.002-12.08]). The expression of PTEN, NKX3.1, SPINK1, DD3, and AMACR genes was significantly deregulated in prostate tumor samples (p range 0.000-0.044). A significant correlation was observed between MAGI2 and NKX3.1 expression in tumor samples (p = 0.006). Furthermore, the inclusion of MAGI2 in the gene panel improved the accuracy for discrimination between PCa and BPH samples with the sensitivity and specificity of 0.88 [CI 0.76-0.95] and 0.83 [CI 0.68-0.92], respectively. The data presented here suggest that MAGI2 gene can be considered as a novel component of gene signatures for the detection of PCa.

Prostate cancer risk after anti-androgen treatment for priapism

BACKGROUND

Patients with recurrent ischemic priapism have historically been treated with anti-androgen therapy due to the limited available evidence for more targeted therapies to treat the underlying pathophysiologic mechanisms of this condition. We report a case in which anti-androgen therapy caused significant adverse side effects and likely masked this patient's elevated prostate-specific antigen (PSA) levels, which adversely impacted the timely diagnosis and treatment of his prostate cancer.

CASE REPORT

A 69-year-old man treated with anti-androgens for priapism initially developed unwanted anti-androgenic side effects such as gynecomastia, erectile dysfunction, and decreased libido. After decreasing his anti-androgen dosage and starting a specified regimen of phosphodiesterase type 5 inhibitor therapy, his serum PSA levels were found to be elevated. He was subsequently diagnosed with adenocarcinoma of the prostate and underwent a radical prostatectomy with the pathologic finding of high-grade, locally progressive disease.

CONCLUSION

Anti-androgen therapy carries significant complication risks, including the potential to alter the diagnosis and treatment of prostate cancer. Clinicians administering this therapy for priapism management should be aware of these possible risks.

Effect of CYP17 and PSA gene polymorphisms on prostate cancer risk and circulating PSA levels in the Slovak population

Cytochrome P-450c17α (CYP17) and prostate-specific antigen (PSA) genes, which are involved in the androgen metabolism cascade, have been studied as possible candidates for genetic influences on prostate cancer development. Contradictory results prompted us to evaluate the frequencies of polymorphisms in the CYP17 and PSA genes as well as the association between these genetic variants and serum PSA levels in prostate cancer patients and men routinely screened for prostate cancer with PSA in the Slovak male population. The CYP17 and PSA polymorphisms were determined by the PCR-RFLP analysis in 197 Caucasian prostate cancer patients and 256 Caucasian controls. We did not find any association between the CYP17 and PSA genotypes and prostate cancer risk overall, or by grade. Also the total serum PSA levels in the cases with the AG or AA genotype were not significantly higher than in the men with the GG genotype (P > 0.05). Our study did not provide support for the hypothesized relationship between CYP17 and PSA gene polymorphisms and prostate cancer in the Slovak male population.

Protease-activated drug development

In this extensive review, we elucidate the importance of proteases and their role in drug development in various diseases with an emphasis on cancer. First, key proteases are introduced along with their function in disease progression. Next, we link these proteases as targets for the development of prodrugs and provide clinical examples of protease-activatable prodrugs. Finally, we provide significant design considerations needed for the development of the next generation protease-targeted and protease-activatable prodrugs.

Significance of incidental focal uptake in prostate on 18-fluoro-2-deoxyglucose positron emission tomography CT images

To evaluate the clinical significance of incidental focal prostate fluorodeoxyglucose (FDG) uptake, we reviewed 18-F-FDG positron emission tomography (PET)/CT scans from 2003 to 2007 and selected cases with focal FDG uptake in prostate. Cases of known prostate cancer were excluded. The maximum standardised uptake value (SUV(max)), site (central or peripheral) and pattern (discrete or ill-defined) of FDG uptake, calcification (present or absent) and prostate volume (<30 or ≥30 cc) were recorded. The PET/CT findings were correlated with serum prostate-specific antigen (PSA) levels, imaging studies, clinical follow-up and biopsy. Of a total of 5119 cases, 63 (1.2%) demonstrated focal FDG uptake in prostate. Eight cases were lost to follow-up. Among the 55 cases with follow-up, malignancy was confirmed by biopsy in 3 (5.4%). The three malignant cases had SUV(max) values of 3.3, 3.6 and 2.3, and all were noted in the peripheral portion of prostate; two of these cases had a discrete FDG uptake pattern, none had calcification corresponding to the FDG uptake area and one had a prostatic volume greater than 30 cc. The mean SUV(max) of 52 benign cases was 3.2 ± 1.7 and focal FDG uptake was noted in the peripheral portion in 34 (65%), 20 (38%) cases showed a discrete FDG uptake pattern, 35 (67%) were accompanied by calcification and 32 (62%) had a prostatic volume greater than 30 cc. The majority of cases demonstrating focal FDG uptake in prostate were benign and no PET/CT finding could reliably differentiate benign from malignant lesions; however, when discrete focal FDG uptake without coincidental calcification is seen, particularly in the peripheral zone of the prostate, further clinical evaluation is recommended.

Molecular assays for the detection of prostate tumor derived nucleic acids in peripheral blood

BACKGROUND

Prostate cancer is the second leading cause of cancer mortality in American men. Although serum PSA testing is widely used for early detection, more specific prognostic tests are needed to guide treatment decisions. Recently, the enumeration of circulating prostate epithelial cells has been shown to correlate with disease recurrence and metastasis following definitive treatment. The purpose of our study was to investigate an immunomagnetic fractionation procedure to enrich circulating prostate tumor cells (CTCs) from peripheral blood specimens, and to apply amplified molecular assays for the detection of prostate-specific markers (PSA, PCA3 and TMPRSS2:ERG gene fusion mRNAs).

RESULTS

As few as five prostate cancer cells were detected per 5 mL of whole blood in model system experiments using anti-EpCAM magnetic particles alone or in combination with anti-PSMA magnetic particles. In our experiments, anti-EpCAM magnetic particles alone exhibited equivalent or better analytical performance with patient samples compared to a combination of anti-EpCAM + anti-PSMA magnetic particles. Up to 39% of men with advanced prostate cancer tested positive with one or more of the molecular assays tested, whereas control samples from men with benign prostate hyperplasia gave consistently negative results as expected. Interestingly, for the vast majority of men who tested positive for PSA mRNA following CTC enrichment, their matched plasma samples also tested positive, although CTC enrichment gave higher overall mRNA copy numbers.

CONCLUSION

CTCs were successfully enriched and detected in men with advanced prostate cancer using an immunomagnetic enrichment procedure coupled with amplified molecular assays for PSA, PCA3, and TMPRSS2:ERG gene fusion mRNAs. Our results indicate that men who test positive following CTC enrichment also exhibit higher detectable levels of non-cellular, circulating prostate-specific mRNAs.

KLK5 gene expression is severely upregulated in androgen-independent prostate cancer cells after treatment with the chemotherapeutic agents docetaxel and mitoxantrone

Kallikrein-related peptidases (KLKs), includingKLK5, have been proposed as promising biomarkers for prostate cancer diagnosis and prognosis. In the present study, we report that distinct augmentations (up to 6.4-fold) ofKLK5mRNA expressional levels, calculated via quantitative real-time PCR, occur after treatment of DU145 cells with appropriate concentrations, determined by the MTT method, of docetaxel and mitoxantrone. Our data reveal the endogenous need of prostate cancer cells for modifiedKLK5expression to cope with the administration of chemotherapeutic drugs. Furthermore, it is proposed that the expression profile ofKLK5could serve as a putative biomarker for monitoring the treatment response in hormone refractory prostate cancer patients.

Expression analysis and study of the KLK15 mRNA splice variants in prostate cancer and benign prostatic hyperplasia

Prostate cancer is the most commonly diagnosed malignancy in male populations in the Western world. The KLK15 gene, the newest member of the kallikrein family, is expressed in the prostate gland. The purpose of this study is the expression analysis and the clinical evaluation of the KLK15 mRNA spliced variants in prostate cancer (CaP) and benign prostatic hyperplasia (BPH) patients. Total RNA was isolated from 104 CaP and BPH tissue specimens. After testing the quality of the RNA, cDNA was produced by reverse transcription, and PCR was performed for the amplification of the KLK15 mRNA transcripts. GAPDH and HPRT genes were used as endogenous controls Our data revealed that mRNA spliced variants of KLK15 were differentially expressed in prostate tissue specimens. Analysis of data showed a statistically significant (P < 0.001) increase in the frequency of overexpression of KLK15 transcripts encoding for both the active isoform and for the isoform 3 in CaP compared to BPH samples. Furthermore, KLK15 transcripts were found to be highly expressed in more aggressive tumors (P = 0.017). These results suggest that KLK15 expression analysis could be employed as a valuable tool for the discrimination between BPH and CaP tissue specimens and as an unfavorable prognostic marker for prostate cancer.

DNA methylation based biomarkers in non-invasive cancer screening

DNA methylation plays a critical role in the regulation of gene expression, differentiation and in the development of cancer and other diseases. Hypermethylation of CpG islands located in the promoter regions of tumor suppressor genes is now firmly established as the most frequent mechanism for gene inactivation in cancers. Feasibility of using DNA methylation based biomarkers for early detection of cancer has been shown. Potential of using DNA methylation for prediction of therapeutic outcome and patient survival has also been shown. DNA originated from cancer cells has been routinely detected in clinical specimens (ex. Plasma/serum, sputum, urine etc.) from cancer patients. Presence of methylated DNA sequences in clinical specimens and potential of using them as biomarkers have been recognized. Novel methylation based biomarkers that can be used in clinical specimens, obtained non-invasively from cancer patients, offer significant practical advantages. More resources need to be committed to this area of biomarker research. Thus, we review recent findings on DNA methylation based cancer biomarkers with particular focus on these applicable to the clinical specimens obtained non-invasively from cancer patients.

FGFR3 mutations in prostate cancer: association with low-grade tumors

Prostate cancer is the second cause of cancer-related death in men of the Western World. The role of FGFR3 and its abnormalities in prostate cancer are not known. FGFR3 mutations have been reported in some human tumors. Few studies have analyzed the mutations of FGFR3 in prostate tumors, and no mutations have been previously reported. Prevalence of FGFR3 somatic mutations was investigated in a series of prostate tumors. The presence of other tumors in these patients, including urothelial, skin, colon, and lung neoplasms, was recorded. Mutational analysis of exons 7, 10, and 15 of FGFR3 revealed 9 mutations in the 112 prostate tumors studied (8%). Most of them consisted of the missense change S249C. The prevalence of mutations in tumors with combined Gleason score=6 is 18% (8/45) compared to 3% (1/36) for tumors with grade=7, and 0% (0/31) for those with grade >or=8 and metastases (P=0.007). The frequency of FGFR3 mutations in autopsy and biopsy samples was 6 and 9%, respectively. The prevalence of FGFR3 mutations in prostate tumors from patients with only prostate cancer was 2% compared to 23% in prostate tumors from patients with other associated neoplasms (P=0.001). This is the first report of molecular changes of FGFR3 in prostate cancer. This gene does not seem to be central to the pathogenesis of prostate cancer, but it is significantly associated with a subgroup of low-grade prostate tumors, and with the finding of other tumors, mainly arising in bladder and skin.

Molecular Pathology of the Genitourinary Tract: Prostate and Bladder

The knowledge of cellular mechanisms in tumors of the prostate and bladder has grown exponentially. Molecular technologies have led to the discovery of TMPRSS2 in prostate cancer and the molecular pathways distinguishing low- and high-grade urothelial neoplasms. UroVysion with fluorescence in situ hybridization is already commonplace as an adjunct to cytologic diagnosis of urothelial neoplasms. This trend portends the future in which classification and diagnosis of tumors of the prostate and bladder through morphologic analysis will be supplemented by molecular information correlating with prognosis and targeted therapy. This article outlines tumor molecular pathology of the prostate and bladder encompassing current genomic, epigenomic, and proteonomic findings.

KLF6 and TP53 mutations are a rare event in prostate cancer: distinguishing between Taq polymerase artifacts and true mutations

Krüppel-like factor 6 (KLF6) has been reported to act as a tumor suppressor gene involved in the regulation of the cell cycle by activating p21 in a p53-independent manner. Many studies suggest that KLF6 is inactivated by allelic loss and somatic mutation. However, there is a high variability in the reported frequency of mutations (from 1 to 55%). TP53 also regulates the cell cycle through the activation of p21. In prostate cancer, the reported frequency of TP53 mutations ranges from 3 to 42%. In all these reports, there is a considerable degree of methodological heterogeneity. Our aim was to determine the frequency of KLF6 and TP53 mutations in a well-defined group of prostate tumors with different stages and Gleason grades. The four exons of KLF6 and exons 4-9 of TP53 were studied in 103 cases, including 90 formalin-fixed, paraffin-embedded (FFPE) and 13 frozen samples. All tumors were analyzed through PCR and direct sequencing. All changes found were confirmed by a second independent PCR and sequencing reaction. For KLF6, mutation (E227G) was only detected in one tumor (1%) and for TP53, three different mutations (L130H, H214R, and Y234C) were detected in five tumors (5%). This low mutation index is in keeping with recent papers on the subject. Our study strongly supports the notion that KLF6 and TP53 mutations are not frequent events in prostate cancer. When using FFPE tissues, it is mandatory to perform at least two independent rounds of PCR and sequencing to confirm mutations and exclude Taq polymerase-induced artifacts.

Annexin A3 in urine: a highly specific noninvasive marker for prostate cancer early detection

PURPOSE

In prostate cancer cases the early diagnosis of tumors carrying a high risk of progression is of the utmost importance. There is an urgent clinical need to avoid unnecessary biopsies and subsequent overtreatment. We validated annexin A3 as a diagnostic marker for prostatic disease in typical clinical populations and relevant segments, such as patients with a negative digital rectal examination and low prostate specific antigen.

MATERIALS AND METHODS

We performed a blinded clinical study (ClinicalTrials.gov Identifier NCT00400894) from September 2005 to January 2007 in 591 patients who were continuously recruited from 4 European urological clinics. Urine was obtained directly after digital rectal examination and the annexin A3 concentration in urine was quantified by Western blot. Statistical analysis included combinations of annexin A3 with total, percent free, complexed and percent complexed prostate specific antigen.

RESULTS

Combined readouts of prostate specific antigen and urinary annexin A3 were superior to all others with an area under the ROC curve of 0.82 for a total prostate specific antigen range of 2 to 6 ng/ml, 0.83 for a total prostate specific antigen range of 4 to 10 ng/ml and 0.81 in all patients. The best performing prostate specific antigen derivative was percent free prostate specific antigen with an area under the ROC curve of 0.68 for a total prostate specific antigen range of 2 to 6 ng/ml, 0.72 for a total prostate specific antigen range of 4 to 10 ng/ml and 0.73 in all patients. Annexin A3 has an inverse relationship to cancer and, therefore, its specificity was much better than that of prostate specific antigen.

CONCLUSIONS

Annexin A3 quantification in urine provides a novel noninvasive biomarker with high specificity. Annexin A3 is complementary to prostate specific antigen or to any other cancer marker. It has a huge potential to avoid unnecessary biopsies with a particular strength in the clinically relevant large group of patients who have a negative digital rectal examination and prostate specific antigen in the lower range of values (2 to 10 ng/ml).

Performance of a single assay for both type III and type VI TMPRSS2:ERG fusions in noninvasive prediction of prostate biopsy outcome

BACKGROUND

TMPRSS2:ERG fusions are promising prostate cancer biomarkers. Because they can occur in multiple forms in a single cancer specimen, we developed a quantitative PCR test that detects both type III and type VI TMPRSS2:ERG fusions. The assay is quantified from a standard curve determined with a plasmid-cloned type III TMPRSS2:ERG fusion target.

METHODS

We collected expressed prostatic secretion (EPS) under an institutional review board-approved, blinded, prospective study from 74 patients undergoing transrectal ultrasound-guided biopsy for prostate cancer. We compared the characteristic performance of the test for type III and type VI TMPRSS2:ERG fusions in predicting biopsy outcome and distinguishing between high and low Gleason scores with similar tests for the expression of PCA3 and DNA methylation levels of the APC, RARB, RASSF1, and GSTP1 genes. We used logistic regression to analyze the effects of multiple biomarkers in linear combinations.

RESULTS

Each test provided a significant improvement in characteristic performance over baseline digital rectal examination (DRE) plus serum prostate-specific antigen (PSA); however, the test for type III and type VI TMPRSS2:ERG fusions yielded the best performance in predicting biopsy outcome [area under the curve (AUC) 0.823, 95% CI 0.728-0.919, P < 0.001] and Gleason grade >7 (AUC 0.844, 95% CI 0.740-0.948, P < 0.001).

CONCLUSIONS

Although each test appears to have diagnostic value, PSA plus DRE plus type III and type VI TMPRSS2:ERG provided the best diagnostic performance in EPS specimens.

Molecular alterations in prostate cancer

Prostate tumors display a range of clinical phenotypes, from indolent to aggressively metastatic. Numerous gene expression profiling studies have been conducted toward the potential molecular staging of these pathologies, however the identification of genetic markers that predict aggressive disease has not yet been demonstrated in the clinical setting. A recent survey of the literature has shown that molecular alterations in prostate carcinomas can occur through a variety of different mechanisms, ranging from upstream epigenetic changes and genetic polymorphisms to downstream modulations through alternative splicing and other post-translational processes, some of which could involve noncoding RNAs. A summary of these results and recommendations for future work are the subject of this review.

Tumour endoproteases: the cutting edge of cancer drug delivery?

Despite progression in anticancer drug development and improvements in the clinical utilization of therapies, current treatment regimes are still dependent upon the use of systemic antiproliferative cytotoxic agents. Although these agents are unquestionably potent, their efficacy is limited by toxicity towards 'normal' cells and a lack of tumour selective targeting, resulting in a therapeutic index which is modest at best. Consequently, the development of more tumour selective cancer treatments, with better discrimination between tumour and normal cells is unequivocally an important goal for cancer drug discovery. One such strategy is to exploit the tumour phenotype as a mechanism for tumour-selective delivery of potent therapeutics. An exciting approach in this area is to develop anticancer therapeutics as prodrugs, which are non-toxic until activated by enzymes localized specifically in the tumour. Enzymes suitable for tumour-activated prodrug development must have increased activity in the tumour relative to non-diseased tissue and an ability to activate the prodrug to its active form. One class of enzyme satisfying these criteria are the tumour endoproteases, particularly the serine- and metallo-proteases. These proteolytic enzymes are essential for tumour angiogenesis, invasion and metastasis, the major defining features of malignancy. This review describes the concept behind development of tumour-endoprotease activated prodrugs and discusses the various studies to date that have demonstrated the huge potential of this approach for improvement of cancer therapy.

Nuclear receptor interaction protein, a coactivator of androgen receptors (AR), is regulated by AR and Sp1 to feed forward and activate its own gene expression through AR protein stability

Previously, we found a novel gene, nuclear receptor interaction protein (NRIP), a transcription cofactor that can enhance an AR-driven PSA promoter activity in a ligand-dependent manner in prostate cancer cells. Here, we investigated NRIP regulation. We cloned a 413-bp fragment from the transcription initiation site of the NRIP gene that had strong promoter activity, was TATA-less and GC-rich, and, based on DNA sequences, contained one androgen response element (ARE) and three Sp1-binding sites (Sp1-1, Sp1-2, Sp1-3). Transient promoter luciferase assays, chromatin immunoprecipitation and small RNA interference analyses mapped ARE and Sp1-2-binding sites involved in NRIP promoter activation, implying that NRIP is a target gene for AR or Sp1. AR associates with the NRIP promoter through ARE and indirectly through Sp1-binding site via AR–Sp1 complex formation. Thus both ARE and Sp1-binding site within the NRIP promoter can respond to androgen induction. More intriguingly, NRIP plays a feed-forward role enhancing AR-driven NRIP promoter activity via NRIP forming a complex with AR to protect AR protein from proteasome degradation. This is the first demonstration that NRIP is a novel AR-target gene and that NRIP expression feeds forward and activates its own expression through AR protein stability.

Progensa PCA3 test for prostate cancer detection

Patients with an elevated serum total prostate-specific antigen value or abnormal digital rectal examination results are at risk of having prostate cancer and should undergo prostate needle biopsies. However, approximately 60% of them will have a negative prostate biopsy result. Therefore, further biopsies are recommended for young patients at risk of prostate cancer with a positive rate of 20-40%. Biomarkers are required in order to avoid unnecessary biopsies. The PCA3 gene product is specifically overexpressed in prostate tumor cells, and modern molecular biology techniques allow us to use a specific test for this gene in order to select patients who have a high risk of having prostate cancer. Literature reviews of the gene product, as well as the first clinical results of the Progensa PCA3 test, are presented.

Genomic biomarkers, androgen pathway and prostate cancer

Prostate cancer is the most frequent male malignancy diagnosed in western countries and the second leading cause of cancer-related deaths. The growth and function of the prostate gland depends on androgens. Owing to the importance of androgens in prostate development, genes involved in androgen biosynthesis and metabolism have been extensively studied. In this review, we address recent progress toward the use of inherited and acquired genetic variants to predict susceptibility and clinical outcomes of prostate cancer patients. Many of these genetic variants involve several genes related to the biosynthesis and metabolism of androgens, such as steroid-5-α-reductase, α polypeptide 2 (SRD5A2), cytochrome P450 (CYP)19A1, CYP17A1, hydroxy-δ-5-steroid dehydrogenase, 3 β- and steroid δ-isomerase 2 (HSD3B2) and androgen receptor (AR). With increasing knowledge, it may be possible to distinguish indolent from aggressive prostate tumors by molecular fingerprinting. Furthermore, with the emergence of new investigative tools, such as microarray platforms and comparative genomic hybridization (CGH) array, a variety of new genomic biomarkers will be available in the future to provide accurate prognostic and monitoring solutions for individualized patient care.