Prostate cancer: the need for biomarkers and new therapeutic targets

The Impact of Lifestyle on Prostate Cancer: A Road to the Discovery of New Biomarkers

Prostate cancer (PCa) is one of the most common cancers among men, and its incidence has been rising through the years. Several risk factors have been associated with this disease and unhealthy lifestyles and inflammation were appointed as major contributors for PCa development, progression, and severity. Despite the advantages associated with the currently used diagnostic tools [prostate-specific antigen(PSA) serum levels and digital rectal examination (DRE)], the development of effective approaches for PCa diagnosis is still necessary. Finding lifestyle-associated proteins that may predict the development of PCa seems to be a promising strategy to improve PCa diagnosis. In this context, several biomarkers have been identified, including circulating biomarkers (CRP, insulin, C-peptide, TNFα-R2, adiponectin, IL-6, total PSA, free PSA, and p2PSA), urine biomarkers (PCA3, guanidine, phenylacetylglycine, and glycine), proteins expressed in exosomes (afamin, vitamin D-binding protein, and filamin A), and miRNAs expressed in prostate tissue (miRNA-21, miRNA-101, and miRNA-182). In conclusion, exploring the impact of lifestyle and inflammation on PCa development and progression may open doors to the identification of new biomarkers. The discovery of new PCa diagnostic biomarkers should contribute to reduce overdiagnosis and overtreatment.

Circ_0044516 Enriches the Level of SARM1 as a miR-330-5p Sponge to Regulate Cell Malignant Behaviors and Tumorigenesis of Prostate Cancer

Prostate cancer (PCa) is one of the most common and deadly cancers in men. The dysregulated circular RNAs (circRNAs) are involved in the development of various cancers, including PCa. The purpose of this study was to construct a circRNA-microRNA (miRNA)-mRNA network to explain the function of circ_0044516 in PCa. The expression analysis of circ_0044516, miR-330-5p, and sterile alpha and TIR motif-containing 1 (SARM1) was performed using real-time quantitative polymerase chain reaction, and the protein level of SARM1 was detected by western blot. The interaction between miR-330-5p and circ_0044516 or SARM1 obtained by bioinformatics prediction was verified by dual-luciferase reporter assay or RNA immunoprecipitation assay. For functional studies, cell proliferation was assessed by cell viability and colony formation ability using cell counting kit-8 assay and colony formation assay. Cell migration and invasion were studied using transwell assay. Cell apoptosis and cell cycle were investigated using flow cytometry assay. The tumorigenicity of circ_0044516 was tested by animal study. Circ_0044516 and SARM1 were highly expressed, while miR-330-5p was rarely expressed in PCa tissues and cells. Circ_0044516 acted as a miR-330-5p sponge to block miR-330-5p expression, and circ_0044516 knockdown suppressed PCa cell proliferation, migration, invasion, and cycle progression by enriching miR-330-5p. SARM1 was a target of miR-330-5p, and miR-330-5p restoration also inhibited PCa cell proliferation, migration, invasion, and cycle progression by degrading SARM1. Moreover, circ_0044516 deficiency blocked tumor growth in vivo by regulating the miR-330-5p/SARM1 axis. Circ_0044516 as a miR-330-5p sponge increases SARM1 expression, thus promoting the malignant development of PCa.

Aromatic amino acids play a harmonizing role in prostate cancer: A metabolomics-based cross-sectional study

BACKGROUND

Prostate cancer (PCa) is a common health problem worldwide. The rate of this disease is likely to grow by 2021. PCa is a heterogeneous disorder, and various biochemical factors contribute to the development of this disease. The metabolome is the complete set of metabolites in a cell or biological sample and represents the downstream end product of the omics. Hence, to model PCa by computational systems biology, a preliminary metabolomics-based study was used to compare the metabolome profile pattern between healthy and PCa men.

OBJECTIVE

This study was carried out to highlight energy metabolism modification and assist the prognosis and treatment of disease with unique biomarkers.

MATERIALS AND METHODS

In this cross-sectional research, 26 men diagnosed with stage-III PCa and 26 healthy men with normal PSA levels were enrolled. Urine was analyzed with proton nuclear magnetic resonance (1 H-NMR) spectroscopy, accompanied by the MetaboAnalyst web-based platform tool for metabolomics data analysis. Partial least squares regression discriminant analysis was applied to clarify the separation between the two groups. Outliers were documented and metabolites determined, followed by identifying biochemical pathways.

RESULTS

Our findings reveal that modifications in aromatic amino acid metabolism and some of their metabolites have a high potential for use as urinary PCa biomarkers. Tryptophan metabolism (p < 0.001), tyrosine metabolism (p < 0.001), phenylalanine, tyrosine and tryptophan biosynthesis (p < 0.001), phenylalanine metabolism (p = 0.01), ubiquinone and other terpenoid-quinone biosynthesis (p = 0.19), nitrogen metabolism (p = 0.21), and thiamine metabolism (p = 0.41) with Q2 (0.198) and R2 (0.583) were significantly altered.

CONCLUSION

The discriminated metabolites and their pathways play an essential role in PCa causes and harmony.

Prostate Cancer Biomarkers: From diagnosis to prognosis and precision-guided therapeutics

Prostate cancer (PCa) is one of the most commonly diagnosed malignancies and among the leading causes of cancer-related death worldwide. It is a highly heterogeneous disease, ranging from remarkably slow progression or inertia to highly aggressive and fatal disease. As therapeutic decision-making, clinical trial design and outcome highly depend on the appropriate stratification of patients to risk groups, it is imperative to differentiate between benign versus more aggressive states. The incorporation of clinically valuable prognostic and predictive biomarkers is also potentially amenable in this process, in the timely prevention of metastatic disease and in the decision for therapy selection. This review summarizes the progress that has so far been made in the identification of the genomic events that can be used for the classification, prediction and prognostication of PCa, and as major targets for clinical intervention. We include an extensive list of emerging biomarkers for which there is enough preclinical evidence to suggest that they may constitute crucial targets for achieving significant advances in the management of the disease. Finally, we highlight the main challenges that are associated with the identification of clinically significant PCa biomarkers and recommend possible ways to overcome such limitations.

Modulating tumor reactive stroma by extracorporeal shock waves to control prostate cancer progression

BACKGROUND

Prostate cancer is the second most common cancer worldwide. Tumor microenvironment is composed of activated fibroblasts, the so called carcinoma-associated fibroblasts (CAFs). They express high levels of α-smooth muscle actin (α-SMA) and type I collagen (COL1), and support proliferation and migration of tumor epithelial cells. Extracorporeal shock waves (ESWs), acoustic waves, are effective in the treatment of hypertrophic scars, due to their ability to modulate fibrosis. Based on this rationale, the study evaluated the effects of ESWs on CAF activation and the influence of ESW-treated CAFs on the growth and migration of epithelial prostatic carcinoma cells.

METHODS

Primary cultures of CAFs (n = 10) were prepared from tumors of patients undergoing surgery for high-risk prostate carcinoma. CAFs were treated with ESWs (energy levels: 0.32 mJ/mm² , 1000 pulses; 0.59 mJ/mm² , 250 pulses). After treatment, the messenger RNA and protein levels of the stromal activation markers α-SMA and COL1 were determined. Subsequently, two different stabilized cell lines (PC3 and DU145) of androgen-resistant prostate cancer were treated with the conditioned media produced by ESW-treated CAFs. At different times, viability and migration of PC3 and DU145 cells were evaluated. Viability was also assessed by coculture system using CAFs and PC3 or DU145 cells.

RESULTS

ESWs reduced gene expression and protein level of α-SMA and COL1 in CAFs. The treatment of PC3 and DU145 with conditioned media of ESW-treated CAFs determined a reduction of their growth and invasive potential. Coculture systems between ESW-treated CAFs and PC3 or DU145 cells confirmed the epithelial cell number reduction.

CONCLUSIONS

This in vitro study demonstrates for the first time that ESWs are able to modulate the activation of prostate CAFs in favor of a less "reactive" stroma, with consequent slowing of the growth and migration of prostate cancer epithelial cells. However, only further studies to be performed in vivo will confirm the possibility of using this new therapy in patients with prostate cancer.

Advances in targeted alpha therapy for prostate cancer

Amongst therapeutic radiopharmaceuticals, targeted alpha therapy (TαT) can deliver potent and local radiation selectively to cancer cells as well as the tumor microenvironment and thereby control cancer while minimizing toxicity. In this review, we discuss the history, progress, and future potential of TαT in the treatment of prostate cancer, including dosimetry-individualized treatment planning, combinations with small-molecule therapies, and conjugation to molecules directed against antigens expressed by prostate cancer cells, such as prostate-specific membrane antigen (PSMA) or components of the tumor microenvironment. A clinical proof of concept that TαT is efficacious in treating bone-metastatic castration-resistant prostate cancer has been demonstrated by radium-223 via improved overall survival and long-term safety/tolerability in the phase III ALSYMPCA trial. Dosimetry calculation and pharmacokinetic measurements of TαT provide the potential for optimization and individualized treatment planning for a precision medicine-based cancer management paradigm. The ability to combine TαTs with other agents, including chemotherapy, androgen receptor-targeting agents, DNA repair inhibitors, and immuno-oncology agents, is under investigation. Currently, TαTs that specifically target prostate cancer cells expressing PSMA represents a promising therapeutic approach. Both PSMA-targeted actinium-225 and thorium-227 conjugates are under investigation. The described clinical benefit, safety and tolerability of radium-223 and the recent progress in TαT trial development suggest that TαT occupies an important new role in prostate cancer treatment. Ongoing studies with newer dosimetry methods, PSMA targeting, and novel approaches to combination therapies should expand the utility of TαT in prostate cancer treatment.

miR-425-5p suppresses tumorigenesis and DDP resistance in human-prostate cancer by targeting GSK3β and inactivating the Wnt/β-catenin signaling pathway

Prostate cancer (PCa) represents the most frequently diagnosed cancer in men. Cisplatin, also known as cis-diamminedichloroplatinum (DDP), is a standard chemotherapeutic agent used to treat PCa, and DDP resistance remains one important obstacle in DDP-based chemotherapy. In our research, we found miR-425-5p was down-regulated in PCa and even lower in DDP-resistant PCa determined by quantitative polymerase chain reaction; in contrast, GSK3β mRNA expression was upregulated in PCa and even higher in DDP-resistant PCa. Moreover, there was a modest but significant inverse correlation between the expression of GSK3β mRNA and miR-425-5p. Functional experiments showed that miR-425-5p mimic inhibited DDP resistance as evidenced by a promoted apoptosis rate (flow cytometry) and suppressed cell viability (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay) and expressions of MDR1 andMRP1 (western blotting) in DU145/DDP and PC3/DDP cells. Luciferase reporter assay and RNA immunoprecipitation identifiedGSK3β was a potential target of miR-425-5p. The effect ofmiR-425-5pmimic on DDP resistance was partially reversed by pcDNA-GSK3β. Mechanically, miR-425-5p mimic reduced expression of β-catenin, cyclin D1 and C-myc, which was further blocked when GSK3β overexpressed. In vivo experiments, recovery of GSK3β prevented xenograft tumor growth and DDP resistance in the presence of miR-425-5p mimic. To sum up, miR-425-5p upregulation might sensitize human PCa to DDP by targeting GSK3β and inactivating the Wnt/β-catenin signaling pathway.

The transcription factor ZEB1 promotes an aggressive phenotype in prostate cancer cell lines

It has been reported that one of the factors that promotes tumoral progression is the abnormal activation of the epithelial-mesenchymal transition program. This process is associated with tumoral cells acquiring invasive and malignant properties and has the transcription factor zinc finger E-box-binding homeobox 1 (ZEB1) as one of its main activators. However, the role of ZEB1 in promoting malignancy in prostate cancer (PCa) is still unclear. Here, we report that ZEB1 expression correlates with Gleason score in PCa samples and that expression of ZEB1 regulates epithelial-mesenchymal transition and malignant characteristics in PCa cell lines. The results showed that ZEB1 expression is higher in samples of higher malignancy and that overexpression of ZEB1 was able to induce epithelial-mesenchymal transition by upregulating the mesenchymal marker Vimentin and downregulating the epithelial marker E-Cadherin. On the contrary, ZEB1 silencing repressed Vimentin expression and upregulated E-Cadherin. ZEB1 expression conferred enhanced motility and invasiveness and a higher colony formation capacity to 22Rv1 cells whereas DU145 cells with ZEB1 silencing showed a decrease in those same properties. The results showed that ZEB1 could be a key promoter of tumoral progression toward advanced stages of PCa.

ZBTB46, SPDEF, and ETV6: Novel Potential Biomarkers and Therapeutic Targets in Castration-Resistant Prostate Cancer

Prostate cancer (PCa) is the second most common killer among men in Western countries. Targeting androgen receptor (AR) signaling by androgen deprivation therapy (ADT) is the current therapeutic regime for patients newly diagnosed with metastatic PCa. However, most patients relapse and become resistant to ADT, leading to metastatic castration-resistant PCa (CRPC) and eventually death. Several proposed mechanisms have been proposed for CRPC; however, the exact mechanism through which CRPC develops is still unclear. One possible pathway is that the AR remains active in CRPC cases. Therefore, understanding AR signaling networks as primary PCa changes into metastatic CRPC is key to developing future biomarkers and therapeutic strategies for PCa and CRPC. In the current review, we focused on three novel biomarkers (ZBTB46, SPDEF, and ETV6) that were demonstrated to play critical roles in CRPC progression, epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI) drug resistance, and the epithelial-to-mesenchymal transition (EMT) for patients treated with ADT or AR inhibition. In addition, we summarize how these potential biomarkers can be used in the clinic for diagnosis and as therapeutic targets of PCa.

Nuclear magnetic resonance spectroscopy as a new approach for improvement of early diagnosis and risk stratification of prostate cancer

Prostate cancer (PCa) is the second most common male cancer worldwide and the fifth leading cause of death from cancer in men. Early detection and risk stratification is the most effective way to improve the survival of PCa patients. Current PCa biomarkers lack sufficient sensitivity and specificity to cancer. Metabolite biomarkers are evolving as a new diagnostic tool. This review is aimed to evaluate the potential of metabolite biomarkers for early detection, risk assessment, and monitoring of PCa. Of the 154 identified publications, 27 and 38 were original papers on urine and serum metabolomics, respectively. Nuclear magnetic resonance (NMR) is a promising method for measuring concentrations of metabolites in complex samples with good reproducibility, high sensitivity, and simple sample processing. Especially urine-based NMR metabolomics has the potential to be a cost-efficient method for the early detection of PCa, risk stratification, and monitoring treatment efficacy.

Differential role of PTEN in transforming growth factor β (TGF-β) effects on proliferation and migration in prostate cancer cells

BACKGROUND

Transforming growth factor-β (TGF-β) acts as a tumor suppressor in normal epithelial cells but as a tumor promoter in advanced prostate cancer cells. PI3-kinase pathway mediates TGF-β effects on prostate cancer cell migration and invasion. PTEN inhibits PI3-kinase pathway and is frequently mutated in prostate cancers. We investigated possible role(s) of PTEN in TGF-β effects on proliferation and migration in prostate cancer cells.

METHODS

Expression of PTEN mRNA and proteins were determined using RT-PCR and Western blotting in RWPE1 and DU145 cells. We also studied the role of PTEN in TGF-β effects on cell proliferation and migration in DU145 cells after transient silencing of endogenous PTEN. Conversely, we determined the role of PTEN in cell proliferation and migration after over-expression of PTEN in PC3 cells which lack endogenous PTEN.

RESULTS

TGF-β1 and TGF-β3 had no effect on PTEN mRNA levels but both isoforms increased PTEN protein levels in DU145 and RWPE1 cells indicating that PTEN may mediate TGF-β effects on cell proliferation. Knockdown of PTEN in DU145 cells resulted in significant increase in cell proliferation which was not affected by TGF-β isoforms. PTEN overexpression in PC3 cells inhibited cell proliferation. Knockdown of endogenous PTEN enhanced cell migration in DU145 cells, whereas PTEN overexpression reduced migration in PC3 cells and reduced phosphorylation of AKT in response to TGF-β.

CONCLUSION

We conclude that PTEN plays a role in inhibitory effects of TGF-β on cell proliferation whereas its absence may enhance TGF-β effects on activation of PI3-kinase pathway and cell migration.

MicroRNA-27a-5p regulation by promoter methylation and MYC signaling in prostate carcinogenesis

Upregulation of MYC and miRNAs deregulation are common in prostate cancer (PCa). Overactive MYC may cause miRNAs’ expression deregulation through transcriptional and post-transcriptional mechanisms and epigenetic alterations are also involved in miRNAs dysregulation. Herein, we aimed to elucidate the role of regulatory network between MYC and miRNAs in prostate carcinogenesis. MYC expression was found upregulated in PCa cases and matched precursor lesions. MicroRNA’s microarray analysis of PCa samples with opposed MYC levels identified miRNAs significantly overexpressed in high-MYC PCa. However, validation of miR-27a-5p in primary prostate tissues disclosed downregulation in PCa, instead, correlating with aberrant promoter methylation. In a series of castration-resistant PCa (CRPC) cases, miR-27a-5p was upregulated, along with promoter hypomethylation. MYC and miR-27a-5p expression levels in LNCaP and PC3 cells mirrored those observed in hormone-naíve PCa and CRPC, respectively. ChIP analysis showed that miR-27a-5p expression is only regulated by c-Myc in the absence of aberrant promoter methylation. MiR-27a-5p knockdown in PC3 cells promoted cell growth, whereas miRNA forced expression in LNCaP and stable MYC-knockdown PC3 cells attenuated the malignant phenotype, suggesting a tumor suppressive role for miR-27a-5p. Furthermore, miR-27a-5p upregulation decreased EGFR/Akt1/mTOR signaling. We concluded that miR-27a-5p is positively regulated by MYC, and its silencing due to aberrant promoter methylation occurs early in prostate carcinogenesis, concomitantly with loss of MYC regulatory activity. Our results further suggest that along PCa progression, miR-27a-5p promoter becomes hypomethylated, allowing for MYC to resume its regulatory activity. However, the altered cellular context averts miR-27a-5p from successfully accomplishing its tumor suppressive function at this stage of disease.

Diagnosis of prostate cancer by analyzing oxidative stress in human seminal plasma: developing unsophisticated tools for noninvasive prostate cancer diagnosis

Prostate-specific antigen blood testing has improved early detection of prostate cancer (PCa); however, PCa mortality has not decreased accordingly and a prostate biopsy is still required for a definitive diagnosis. Proteomic biomarker screening in easily available body fluids such as seminal plasma is now increasingly being proposed as a solution to improve PCa detection and prognosis. PCa cells typically produce high levels of reactive oxygen species (ROS). In this study, we therefore investigated ROS levels in semen samples from patients with a negative or a positive prostate biopsy to predict PCa diagnosis. Multiple clinicopathological parameters (digital rectal examination, prostate-specific antigen scoring, prostate biopsy, and ROS levels) of patients examined for PCa were measured. No significant differences in ROS levels were detected in relation to PCa diagnosis. Although seminal plasma is a well-suited medium for prostate-related biomarkers, no significant differences in ROS levels were observed between the patient groups. Comparison with ROS levels encountered in semen of larger patient groups is the next logical step.

Diagnostic values of serum tumor markers Cyfra21-1, SCCAg, ferritin, CEA, CA19-9, and AFP in oral/oropharyngeal squamous cell carcinoma

Background

At present, the research on serum tumor markers in the early diagnosis of malignant tumors has aroused widespread concern. The aim of this study was to investigate the diagnostic values of serum tumor markers cytokeratin 19 fragment (Cyfra21-1), squamous cell carcinoma antigen (SCCAg), ferritin, carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), and α-fetoprotein (AFP) for patients with oral/oropharyngeal squamous carcinoma (OSCC/OPSCC).

Methods

One hundred and sixty-nine cases of patients with OSCC/OPSCC as the experimental group, 86 cases of oral benign tumor patients as the control group, and 30 cases of healthy people as the normal control group were studied. The levels of serum Cyfra21-1, SCCAg, ferritin, CEA, CA19-9, and AFP were measured using electrochemiluminescence immunoassay.

Results

The levels of serum Cyfra21-1, SCCAg, ferritin, and CEA in patients with OSCC/OPSCC were significantly higher than those of benign tumor and healthy control group (P<0.05). The levels of CA19-9 and AFP showed no significant difference between patients with OSCC/OPSCC, benign tumor, and healthy group (P>0.05). The level of serum Cyfra21-1 in patients with early OSCC/OPSCC (stage I + II) was significantly higher than that of benign tumor and healthy control group (P<0.05). However, the levels of serum SCCAg, ferritin, CEA, CA19-9, and AFP showed no significant difference between patients with early OSCC/OPSCC, benign tumor, and healthy control group (P>0.05). The levels of serum Cyfra21-1, SCCAg, ferritin, and CEA in the middle-late stage of patients with OSCC/OPSCC (stage III + IV) were significantly higher than those of patients with the early OSCC/OPSCC, benign tumor, and healthy control group (P<0.05). The diagnostic cutoff levels of Cyfra21-1, SCCAg, ferritin, and CEA were 2.17, 0.72, 109.95, and 1.99 ng/mL, respectively. The sensitivities were 60.36%, 73.37%, 81.66%, and 66.27%, respectively. The specificities were 81.03%, 68.10%, 40.52%, and 61.21%, respectively.

Conclusion

Cyfra21-1, SCCAg, ferritin, and CEA had diagnostic values for patients with OSCC/OPSCC. Meanwhile, Cyfra21-1 had better early diagnostic value for patients with OSCC/OPSCC.

DNA damage signalling barrier, oxidative stress and treatment-relevant DNA repair factor alterations during progression of human prostate cancer

The DNA damage checkpoints provide an anti-cancer barrier in diverse tumour types, however this concept has remained unexplored in prostate cancer (CaP). Furthermore, targeting DNA repair defects by PARP1 inhibitors (PARPi) as a cancer treatment strategy is emerging yet requires suitable predictive biomarkers. To address these issues, we performed immunohistochemical analysis of multiple markers of DNA damage signalling, oxidative stress, DNA repair and cell cycle control pathways during progression of human prostate disease from benign hyperplasia, through intraepithelial neoplasia to CaP, complemented by genetic analyses of TMPRSS2-ERG rearrangement and NQO1, an anti-oxidant factor and p53 protector. The DNA damage checkpoint barrier (γH2AX, pATM, p53) mechanism was activated during CaP tumorigenesis, albeit less and with delayed culmination compared to other cancers, possibly reflecting lower replication stress (slow proliferation despite cases of Rb loss and cyclin D1 overexpression) and progressive loss of ATM activator NKX3.1. Oxidative stress (8-oxoguanine lesions) and NQO1 increased during disease progression. NQO1 genotypes of 390 men did not indicate predisposition to CaP, yet loss of NQO1 in CaP suggested potential progression-opposing tumour suppressor role. TMPRSS2-ERG rearrangement and PTEN loss, events sensitizing to PARPi, occurred frequently along with heterogeneous loss of DNA repair factors 53BP1, JMJD1C and Rev7 (all studied here for the first time in CaP) whose defects may cause resistance to PARPi. Overall, our results reveal an unorthodox DNA damage checkpoint barrier scenario in CaP tumorigenesis, and provide novel insights into oxidative stress and DNA repair, with implications for biomarker guidance of future targeted therapy of CaP.

MicroRNA-410-5p as a potential serum biomarker for the diagnosis of prostate cancer

Background

Prostate cancer (PCa) remains to be a diagnostic challenge due to its variable presentation and the lack of reliable diagnosis tool. MicroRNAs (miRNAs) regulate gene in extensive range of pathophysiologic processes. Plasma miRNAs are ideal biomarkers in heart failure, diabetes and other disease. However, using circulating miRNAs as biomarkers for the diagnosis of PCa is still unknown.

Methods

149 PCa patients, 57 healthy controls, and 121 non-cancer patients (benign prostatic hyperplasia and other urinary diseases) were enrolled in this study. The reverse transcription of miRNA and SYBR-Green-based double standards curve miRNA quantitative polymerase chain reactions (qPCR) were used to evaluate the dysregulated miR-410-5p. Receiver operator characteristic (ROC) curve analysis was used to evaluate the diagnostic accuracy of miR-410-5p identified as the alternative biomarker.

Results

Circulating miRNA-410-5p (miR-410-5p) level was significantly higher in the PCa patients than in healthy controls or non-cancer patients. ROC curve analysis showed that plasma miR-410-5p was a specific diagnostic biomarker of PCa with an area under curve(AUC) of 0.8097 (95 % confidence interval, 0.7371–0.8823; P < 0.001).

Conclusions

The serum miR-410-5p level is a potential biomarker for the diagnosis of PCa.

Flightless I Homolog Represses Prostate Cancer Progression through Targeting Androgen Receptor Signaling

PURPOSE

Flightless I (FLII), member of the gelsolin superfamily of actin-remodeling proteins, functions as a transcriptional coregulator. We aim to evaluate a tumor-suppressive function of FLII in regulating androgen receptor (AR) in prostate cancer progression.

EXPERIMENTAL DESIGN

We examined FLII protein and mRNA expression in clinical prostate cancer specimens by immunohistochemistry. Kaplan-Meier analysis was conducted to evaluate the difference in disease-overall survival associated with the expression levels of FLII and AR. Prostate cancer cells stably expressing FLII or shRNA knockdown were used for functional analyses. Immunoprecipitation, Luciferase reporter, and immunofluorescence staining assays were performed to examine the functional interaction between FLII and AR.

RESULTS

Our analysis of the expression levels of FLII in a clinical gene expression array dataset showed that the expression of FLII was positively correlated with the overall survival of prostate cancer patients exhibiting high levels of AR expression. Examination of protein and mRNA levels of FLII showed a significant decrease of FLII expression in human prostate cancers. AR and FLII formed a complex in a ligand-dependent manner through the ligand-binding domain (LBD) of AR. Subsequently, we observed a competitive binding to AR between FLII and the ligand. FLII inhibited AR transactivation and decreased AR nuclear localization. Furthermore, FLII contributed to castration-sensitive and castration-resistant prostate cancer cell growth through AR-dependent signaling, and reintroduction of FLII in prostate cancer cells sensitized the cells to bicalutamide and enzalutamide treatment.

CONCLUSIONS

FLII plays a tumor-suppressive role and serves as a crucial determinant of resistance of prostate cancer to endocrine therapies.

Frequency of Unnecessarily Biopsies among Patients with Suspicion of Prostate Cancer in Syrian Men

BACKGROUND

The prevalence of prostate cancer is considered high in many countries, and screening tests are very important in order to detect prostate cancer in its early stages; however false positivity with these screening tests means that a lot of patients undergo unnecessary biopsy, which is an invasive procedure, for the confirmatory test. The purpose of this study was to estimate the frequency of unnecessary biopsy cases in patients referred for prostate biopsy in one of the most important and overload cancer centers in Syria.

MATERIALS AND METHODS

Retrospective data for a period of four years between January 2009 and December 2012 were collected in Al- Bayrouni University Medical hospital in Damascus, Syria. The patients from whom data were collected were referred to our histopathological department because of elevated prostate specific antigen (PSA) serum or an abnormal digital rectal examination (DRE). All patients underwent prostatic TRUS-guided biopsies. Diagnosis of prostate cancer (PCa) or benign prostatic hyperplasia (BPH) was based on histopathological examination and prostate cancers cases were graded and scored according to the Gleason score system.

RESULTS

For the 406 patients referred to biopsy, the mean±SD age was 58.4 ±23.3 years. The mean ± SD PSA level was 49.2±21.5 ng/ ml. Of the total we found 237 patients diagnosed with PCa (58. 4%), 166 patients with BPH (40.9%) and 3 cases were unable to be diagnosed (0.7%) because of biopsy collection errors.

CONCLUSIONS

Our study shows that a high percentage of patients are undergoing unnecessary biopsy, which suggests that the performed screening tests had a high level of false positive and may need re-evaluation.

The inhibitory effects of AR/miR-190a/YB-1 negative feedback loop on prostate cancer and underlying mechanism

Prostate cancer at advanced stages including metastatic and castration-resistant cancer remains incurable due to the lack of effective therapies. MiR-190a belongs to the small noncoding RNA family and has an important role in breast cancer metastasis. However, it is still unknown whether miR-190a plays a role in prostate cancer development. Herein, we first observed AR/miR-190a/YB-1 forms an auto-regulatory negative feedback loop in prostate cancer: miR-190a expression was down-regulated by AR activation; YB-1 functions are as an AR activator; miR-190a inhibited AR expression and transactivation through direct binding to 3′UTR of YB-1 gene. MiR-190a contributes the human prostate cancer cell growth through AR-dependent signaling. Moreover, we examined the expression of miR-190a and observed a significant decrease in human prostate cancers. Reduced expression of miR-190a was inversely correlated to AR levels of prostate cancer patients, and patients with higher miR-190a expression in their tumor have improved tumor-free survival. Taken together, our findings identified a biochemical and functional link between miR-190a with reduced expression in advanced prostate cancer, YB-1 and AR signaling in prostate cancer.

Relative mRNA expression of prostate-derived E-twenty-six factor and E-twenty-six variant 4 transcription factors, and of uridine phosphorylase-1 and thymidine phosphorylase enzymes, in benign and malignant prostatic tissue

Prostate cancer is the most frequent urological tumor, and the second most common cancer diagnosed in men. Incidence and mortality are variable and appear to depend on behavioral factors and genetic predisposition. The prostate-derived E-twenty-six factor (PDEF) and E-twenty-six variant 4 (ETV4) transcription factors, and the thymidine phosphorylase (TP) and uridine phosphorylase-1 (UP-1) enzymes, are reported to be components of the pathways leading to tumorigenesis and/or metastasis in a number of tumors. The present study aimed to analyze the mRNA expression levels of these proteins in prostatic cancerous and benign tissue, and their association with clinical and pathological variables. Using quantitative reverse transcription polymerase chain reaction, the mRNA expression levels of PDEF, ETV4, TP and UP-1 were studied in 52 tissue samples (31 of benign prostatic hyperplasia and 21 of prostate adenocarcinomas) obtained from patients treated by transurethral resection of the prostate or by radical prostatectomy. Relative expression was assessed using the ∆-CT method. Data was analyzed using Spearman's tests for correlation. P<0.05 was considered to indicate a statistically significant difference. The results revealed that PDEF, ETV4, UP-1 and TP were expressed in 85.7, 90.5, 95.2 and 100% of the prostate cancer samples, and in 90.3, 96.8, 90.3 and 96.8% of the benign samples, respectively. PDEF and ETV4 exhibited a significantly higher relative expression level in the tumor samples compared with their benign counterparts. The relative expression of TP and UP-1 did not differ significantly between benign and cancerous prostate tissues. The relative expression of TP was moderately and significantly correlated with the expression of ETV4 in the benign tissues. The relative expression of UP-1 was significantly lower in T3 compared with T1 and T2 cancers. These findings indicate that PDEF, ETV4, TP and UP-1 are typically expressed in benign and malignant prostatic tissues. Further studies are necessary to define the role of these proteins as therapeutic targets in prostate cancer.

Phosphoprotein phosphatase 1-interacting proteins as therapeutic targets in prostate cancer

Prostate cancer is a major public health concern worldwide, being one of the most prevalent cancers in men. Great improvements have been made both in terms of early diagnosis and therapeutics. However, there is still an urgent need for reliable biomarkers that could overcome the lack of cancer-specificity of prostate-specific antigen, as well as alternative therapeutic targets for advanced metastatic cases. Reversible phosphorylation of proteins is a post-translational modification critical to the regulation of numerous cellular processes. Phosphoprotein phosphatase 1 (PPP1) is a major serine/threonine phosphatase, whose specificity is determined by its interacting proteins. These interactors can be PPP1 substrates, regulators, or even both. Deregulation of this protein-protein interaction network alters cell dynamics and underlies the development of several cancer hallmarks. Therefore, the identification of PPP1 interactome in specific cellular context is of crucial importance. The knowledge on PPP1 complexes in prostate cancer remains scarce, with only 4 holoenzymes characterized in human prostate cancer models. However, an increasing number of PPP1 interactors have been identified as expressed in human prostate tissue, including the tumor suppressors TP53 and RB1. Efforts should be made in order to identify the role of such proteins in prostate carcinogenesis, since only 26 have yet well-recognized roles. Here, we revise literature and human protein databases to provide an in-depth knowledge on the biological significance of PPP1 complexes in human prostate carcinogenesis and their potential use as therapeutic targets for the development of new therapies for prostate cancer.

Exosomes as divine messengers: are they the Hermes of modern molecular oncology?

Exosomes are cell-derived vesicles that convey key elements with the potential to modulate intercellular communication. They are known to be secreted from all types of cells, and are crucial messengers that can regulate cellular processes by 'trafficking' molecules from cells of one tissue to another. The exosomal content has been shown to be broad, composed of different types of cytokines, growth factors, proteins, or nucleic acids. Besides messenger RNA (mRNA) they can also contain noncoding transcripts such as microRNAs (miRNAs), which are small endogenous cellular regulators of protein expression. In diseases such as cancer, exosomes can facilitate tumor progression by altering their vesicular content and supplying the tumor niche with molecules that favor the progression of oncogenic processes such as proliferation, invasion and metastasis, or even drug resistance. The packaging of their molecular content is known to be tissue specific, a fact that makes them interesting tools in clinical diagnostics and ideal candidates for biomarkers. In the current report, we describe the main properties of exosomes and explain their involvement in processes such as cell differentiation and cell death. Furthermore, we emphasize the need of developing patient-targeted treatments by applying the conceptualization of exosomal-derived miRNA-based therapeutics.