Circulating miRNAs in localized/locally advanced prostate cancer patients after radical prostatectomy and radiotherapy

Cell-free and extracellular vesicle microRNAs with clinical utility for solid tumors

As cutting-edge technologies applied for the study of body fluid molecular biomarkers are continuously evolving, clinical applications of these biomarkers improve. Diverse forms of circulating molecular biomarkers have been described, including cell-free DNA (cfDNA), circulating tumor cells (CTCs), and cell-free microRNAs (cfmiRs), although unresolved issues remain in their applicability, specificity, sensitivity, and reproducibility. Translational studies demonstrating the clinical utility and importance of cfmiRs in multiple cancers have significantly increased. This review aims to summarize the last 5 years of translational cancer research in the field of cfmiRs and their potential clinical applications to diagnosis, prognosis, and monitoring disease recurrence or treatment responses with a focus on solid tumors. PubMed was utilized for the literature search, following rigorous exclusion criteria for studies based on tumor types, patient sample size, and clinical applications. A total of 136 studies on cfmiRs in different solid tumors were identified and divided based on tumor types, organ sites, number of cfmiRs found, methodology, and types of biofluids analyzed. This comprehensive review emphasizes clinical applications of cfmiRs and summarizes underserved areas where more research and validations are needed.

Radio-miRs: a comprehensive view of radioresistance-related microRNAs

Radiotherapy is a key treatment option for a wide variety of human tumors, employed either alone or alongside with other therapeutic interventions. Radiotherapy uses high-energy particles to destroy tumor cells, blocking their ability to divide and proliferate. The effectiveness of radiotherapy is due to genetic and epigenetic factors that determine how tumor cells respond to ionizing radiation. These factors contribute to the establishment of resistance to radiotherapy, which increases the risk of poor clinical prognosis of patients. Although the mechanisms by which tumor cells induce radioresistance are unclear, evidence points out several contributing factors including the overexpression of DNA repair systems, increased levels of reactive oxygen species, alterations in the tumor microenvironment, and enrichment of cancer stem cell populations. In this context, dysregulation of microRNAs or miRNAs, critical regulators of gene expression, may influence how tumors respond to radiation. There is increasing evidence that miRNAs may act as sensitizers or enhancers of radioresistance, regulating key processes such as the DNA damage response and the cell death signaling pathway. Furthermore, expression and activity of miRNAs have shown informative value in overcoming radiotherapy and long-term radiotoxicity, revealing their potential as biomarkers. In this review, we will discuss the molecular mechanisms associated with the response to radiotherapy and highlight the central role of miRNAs in regulating the molecular mechanisms responsible for cellular radioresistance. We will also review radio-miRs, radiotherapy-related miRNAs, either as sensitizers or enhancers of radioresistance that hold promise as biomarkers or pharmacological targets to sensitize radioresistant cells.

Influence of radical prostatectomy on miRNA dynamics in urine extracellular vesicles

PURPOSE

Cancer statistics demonstrate leading growth of prostate cancer. As a rule, radical prostatectomy (RP) is a mandatory option in the treatment of localized prostate cancer (PCa). Over 30% of patients develop biochemical resistance after the surgery and over 30% of these patients experience prostate cancer recurrence and metastasis. Currently used PCa patient's diagnostic features fail to identify PCa recurrence. To identify the risk group of PCa patients after RP we attempt to apply miRNAs which were shown as promising liquid biopsy markers for PCa diagnosis and prognosis.

MATERIALS AND METHODS

Expression of 14 miRNAs closely involved in the development of prostate cancer from urine extracellular vesicles (uEV) of PCa patients before as well as 3, 6 and 12 months after radical prostatectomy was assessed using RT PCR and compared with their expression from uEV of healthy donors in the current study.

RESULTS

It was shown that 22 miRNA pairs prognostic ratios (MPPRs) significantly changed after radical prostatectomy. MPPRs the most promising in terms of evaluating the effectiveness of radical prostatectomy have been identified. These include two groups: MPPRs significantly changed after surgery towards that in healthy donors; and MPPRs, which divided PCa patients into two significantly different subgroups 3 or 6 months after radical prostatectomy.

CONCLUSIONS

The obtained data indicate that urine EVs represent a valuable source of both MPDR and MPPR for prostate cancer.

Blood-Derived Extracellular Vesicles as a Promising Liquid Biopsy Diagnostic Tool for Early Cancer Detection

Cancer poses a significant public health challenge worldwide, and timely screening has the potential to mitigate cancer progression and reduce mortality rates. Currently, early identification of most tumors relies on imaging techniques and tissue biopsies. However, the use of low-cost, highly sensitive, non-invasive detection methods for early cancer screening has become more attractive. Extracellular Vesicles (EVs) released by all living cells contain distinctive biological components, such as nucleic acids, proteins, and lipids. These vesicles play crucial roles in the tumor microenvironment and intercellular communication during tumor progression, rendering liquid biopsy a particularly suitable method for diagnosis. Nevertheless, challenges related to purification methods and validation of efficacy currently hinder its widespread clinical implementation. These limitations underscore the importance of refining isolation techniques and conducting comprehensive investigations on EVs. This study seeks to evaluate the potential of liquid biopsy utilizing blood-derived EVs as a practical, cost-effective, and secure approach for early cancer detection.

Evaluating circulating cell-free DNA and DNA integrity index as biomarkers in non-small cell lung cancer

BACKGROUND

Analysis of free DNA molecules shed from tumour cells in plasma of patients referred as circulating tumour DNA (ctDNA) with reference to physiological circulating cell-free DNA (cfDNA) is nowadays exploited as liquid biopsy and is considered a new emerging promising biomarker for diagnosis, selection of proper treatment, and prognosis of cancer. DNA integrity index (DII) is assessed by calculating the ratio between the concentration of long cfDNA strands released from tumour cells (ALU247) and the short strands released from normal cells (ALU115). The aim of the current study was to evaluate DII as a potential diagnostic and prognostic biomarker of NSCLC.

METHODS

Our study included 48 NSCLC patients diagnosed as primary NSCLC before starting treatment, 30 COPD patients diagnosed clinically, radiologically, and subjected to chest high-resolution computerized tomography, and 40 healthy controls. cfDNA concentration and DII were measured by quantitative real-time polymerase chain reaction (qPCR).

RESULTS

ALU115, ALU247, and DII were significantly higher in NSCLC compared to COPD patients (p < 0.0001) and controls (p < 0.0001) and in COPD patients compared to control subjects (p < 0.0001). DII positively correlated with the stage of tumour (p = 0.01), tumour metastasis (p = 0.004), and with adenocarcinoma compared to other histopathological types (p = 0.02). To evaluate clinical utility of DII in NSCLC, ROC curve analysis demonstrated an AUC of 0.91 at a cut-off value of 0.44 with total accuracy = 85.6%, sensitivity = 90%, specificity = 83%, PPV = 78.1%, and NPV = 92.1%.

CONCLUSION

cfDNA and DII represent a promising diagnostic and prognostic tool in NSCLC. This type of noninvasive liquid biopsy revealed its chance in the screening, early diagnosis, and monitoring of NSCLC.

BL-MOL-AR Project, Preliminary Results about Liquid Biopsy: Molecular Approach Experience and Research Activity in Oncological Settings

Background  Liquid biopsy is mainly used to identify tumor cells in pulmonary neoplasms. It is more often used in research than in clinical practice. The BL-MOL-AR study aims to investigate the efficacy of next-generation sequencing (NGS) and clinical interpretation of the circulating free DNA (cfDNA) levels. This study reports the preliminary results from the first samples analyzed from patients affected by various neoplasms: lung, intestinal, mammary, gastric, biliary, and cutaneous. Methods  The Biopsia Liquida-Molecolare-Arezzo study aims to enroll cancer patients affected by various malignancies, including pulmonary, intestinal, advanced urothelial, biliary, breast, cutaneous, and gastric malignancies. Thirty-nine patients were included in this preliminary report. At time zero, a liquid biopsy is executed, and two types of NGS panels are performed, comprising 17 genes in panel 1, which is already used in the routine tissue setting, and 52 genes in panel 2. From the 7th month after enrollment, 10 sequential liquid biopsies are performed up to the 17th month. The variant allele frequency (%) and cfDNA levels (ng/mL) are measured in every plasmatic sample. Results  The NGS results obtained by different panels are similar even though the number of mutations is more concordant for lung pathologies. There are no significant differences in the actionability levels of the identified variants. Most of the molecular profiles of liquid biopsies reflect tissue data. Conclusions  Preliminary data from this study confirm the need to clarify the limitations and potential of liquid biopsy beyond the lung setting. Overall, parameters related to cfDNA levels and variant allele frequency could provide important indications for prognosis and disease monitoring.

MiRNA biomarkers in cancers of the male reproductive system: are we approaching clinical application?

BACKGROUND

Specific cancer types face specific clinical management challenges. Owing to their stability, robustness and fast, easy, and cost-effective detection, microRNAs (miRNAs) are attractive candidate biomarkers to the clinic.

OBJECTIVES

Based on a comprehensive review of the relevant literature in the field, we explore the potential of miRNAs as biomarkers to answer relevant clinical dilemmas inherent to cancers of the male reproductive tract (prostate (PCa), testis (TGCTs) and penis (PeCa)) and identify some of the challenges/limitations hampering their widely application.

RESULTS AND DISCUSSION

We conclude that the use of miRNAs as biomarkers is at different stages for these distinct cancer types. While for TGCTs, miRNA-371a-3p is universally accepted to fill in important clinicals gaps and is moving fast towards clinical implementation, for PCa almost no overlap of miRNAs exists between studies, denoting the absence of a consistent miRNA biomarker, and for PeCa the field of miRNAs has just recently started, with only a few studies attempting to explore their clinical usefulness.

CONCLUSION

Technological advances influencing miRNA detection and quantification will be instrumental to continue to move forward with implementation of miRNAs in the clinic as biomarkers for non-invasive diagnosis, risk stratification, treatment monitoring and follow-up. This article is protected by copyright. All rights reserved.

The potential of cell-free and exosomal microRNAs as biomarkers in liquid biopsy in patients with prostate cancer

PURPOSE

Prostate cancer (PCa) is the 4th most diagnosed cancer and the 8th leading cause of cancer-related death worldwide. Currently, clinical risk stratification models including factors like PSA levels, Gleason score, and digital rectal examination are used for this purpose. There is a need for novel biomarkers that can distinguish between indolent and aggressive pathology and reduce the risk of overdiagnosis/overtreatment. Liquid biopsy has a non-invasive character, can lead to less morbidity and provide new biomarkers, such as miRNAs, that regulate diverse important cellular processes. Here, we report an extended revision about the role of cell-free and exosomal miRNAs (exomiRNAs) as biomarkers for screening, diagnosis, prognosis, or treatment of PCa.

METHODS

A comprehensive review of the published literature was conducted focusing on the usefulness, advantages, and clinical applications of cell-free and exomiRNAs in serum and plasma. Using PubMed database 53 articles published between 2012 and 2021 were selected and discussed from the perspective of their use as diagnostic, prognostic and therapeutic biomarkers for PCa.

RESULTS

We identify 119 miRNAs associated with PCa development and the cell-free and exosomal miR-21, miR-141, miR-200c, and miR-375 were consistently associated with progression in multiple cohorts/studies. However, standardized experimental procedures, and well-defined and clinically relevant cohort studies are urgently needed to confirm the biomarker potential of cell-free and exomiRNAs in serum or plasma.

CONCLUSION

Cell-free and exomiRNAs in serum or plasma are promising tools for be used as non-invasive biomarkers for diagnostic, prognosis, therapy improvement and clinical outcome prediction in PCa patients.

MicroRNA-125b-5p Correlates With Prognosis and Lung Adenocarcinoma Progression

A growing number of studies have focused on investigating microRNAs as crucial regulators in the progression of multiple cancer types. Nevertheless, the biological effects and immunological role of miR-125b-5p in non-small cell lung cancer (lung adenocarcinoma, LUAD) have not been determined. The present study aimed to examine the function of miR-125b-5p on cell proliferation and the outcomes of LUAD patients. We utilized diverse public databases in the analysis of the expression, prognosis, diagnostic value, and immune role of miR-125b-5p in non-small cell lung cancer. The growth curve, colony formation, flow cytometry, and Transwell and invasion assays were utilized to determine the function of miR-125b-5p in LUAD progression. In this study, we found that miR-125b-5p was decreased in LUAD and correlated with poor prognosis. Pathway analyses revealed that miR-125b-5p was mainly involved in cell proliferation and immune regulation. Moreover, in vitro experiments indicated that the overexpression of miR-125b-5p significantly inhibited cell proliferation, migration, and invasion and induced cell apoptosis of LUAD. Finally, we discovered that miR-125b-5p correlated with immune cell infiltration. In summary, these results demonstrated that miR-125b-5p serves as a prognostic marker and a therapeutic target for LUAD.

Circulating RNAs in prostate cancer patients

Growing bodies of evidence have demonstrated that the identification of prostate cancer (PCa) biomarkers in the patients' blood and urine may remarkably improve PCa diagnosis and progression monitoring. Among diverse cancer-derived circulating materials, extracellular RNA molecules (exRNAs) represent a compelling component to investigate cancer-related alterations. Once outside the intracellular environment, exRNAs circulate in biofluids either in association with protein complexes or encapsulated inside extracellular vesicles (EVs). Notably, EV-associated RNAs (EV-RNAs) were used for the development of several assays (such as the FDA-approved Progensa Prostate Cancer Antigen 3 (PCA3 test) aiming at improving early PCa detection. EV-RNAs encompass a mixture of species, including small non-coding RNAs (e.g. miRNA and circRNA), lncRNAs and mRNAs. Several methods have been proposed to isolate EVs and relevant RNAs, and to perform RNA-Seq studies to identify potential cancer biomarkers. However, EVs in the circulation of a cancer patient include a multitude of diverse populations that are released by both cancer and normal cells from different tissues, thereby leading to a heterogeneous EV-RNA-associated transcriptional signal. Decrypting the complexity of such a composite signal is nowadays the major challenge faced in the identification of specific tumor-associated RNAs. Multiple deconvolution algorithms have been proposed so far to infer the enrichment of cancer-specific signals from gene expression data. However, novel strategies for EVs sorting and sequencing of RNA associated to single EVs populations will remarkably facilitate the identification of cancer-related molecules. Altogether, the studies summarized here demonstrate the high potential of using EV-RNA biomarkers in PCa and highlight the urgent need of improving technologies and computational approaches to characterize specific EVs populations and their relevant RNA cargo.

Prognostic value of miR-21 for prostate cancer: a systematic review and meta-analysis

Elevated levels of miR-21 expression are associated with many cancers, suggesting it may be a promising clinical biomarker. In prostate cancer (PCa), however, there is still no consensus about the usefulness of miR-21 as an indicator of disease progression. This systematic review and meta-analysis was conducted to investigate the value of miR-21 expression as a prognostic measurement in PCa patients. Medline (Ovid), EMBASE, Web of Science, Scopus and Cochrane Library databases were systematically searched for relevant publications between 2010 to 2021. Studies exploring the relationship between miR-21 expression, PCa prognosis and clinicopathological factors were selected for review. Those reporting hazard ratio (HR) and 95% confidence intervals (CIs) were subject to meta-analyses. Fixed-effect models were employed to calculated pooled HRs and 95% CIs. Risk of bias in each study was assessed using QUIPS tool. Certainty of evidence in each meta-analysis was assessed using GRADE guidelines. A total of 64 studies were included in the systematic review. Of these, 11 were eligible for inclusion in meta-analysis. Meta-analyses revealed that high miR-21 expression was associated with poor prognosis: HR = 1.58 (95% CI = 1.19–2.09) for biochemical recurrence, MODERATE certainty; HR = 1.46 (95% CI = 1.06–2.01) for death, VERY LOW certainty; and HR = 1.26 (95% CI = 0.70–2.27) for disease progression, VERY LOW certainty. Qualitative summary revealed elevated miR-21 expression was significantly positively associated with PCa stage, Gleason score and risk groups. This systematic review and meta-analysis suggests that elevated levels of miR-21 are associated with poor prognosis in PCa patients. miR-21 expression may therefore be a useful prognostic biomarker in this disease.

The Influence of miRNAs on Radiotherapy Treatment in Prostate Cancer - A Systematic Review

In the last years, extensive investigation on miRNomics have shown to have great advantages in cancer personalized medicine regarding diagnosis, treatment and even clinical outcomes. Prostate cancer (PCa) is the second most common male cancer and about 50% of all PCa patients received radiotherapy (RT), despite some of them develop radioresistance. Here, we aim to provide an overview on the mechanisms of miRNA biogenesis and to discuss the functional impact of miRNAs on PCa under radiation response. As main findings, 23 miRNAs were already identified as being involved in genetic regulation of PCa cell response to RT. The mechanisms of radioresistance are still poorly understood, despite it has been suggested that miRNAs play an important role in cell signaling pathways. Identification of miRNAs panel can be thus considered an upcoming and potentially useful strategy in PCa diagnosis, given that radioresistance biomarkers, in both prognosis and therapy still remains a challenge.

Blood-Derived Biomarkers of Diagnosis, Prognosis and Therapy Response in Prostate Cancer Patients

Prostate cancer is among the most frequent cancers in men worldwide. Despite the fact that multiple therapeutic alternatives are available for its treatment, it is often discovered in an advanced stage as a metastatic disease. Prostate cancer screening is based on physical examination of prostate size and prostate-specific antigen (PSA) level in the blood as well as biopsy in suspect cases. However, these markers often fail to correctly identify the presence of cancer, or their positivity might lead to overdiagnosis and consequent overtreatment of an otherwise silent non-progressing disease. Moreover, these markers have very limited if any predictive value regarding therapy response or individual risk for therapy-related toxicities. Therefore, novel, optimally liquid biopsy-based (blood-derived) markers or marker panels are needed, which have better prognostic and predictive value than the ones currently used in the everyday routine. In this review the role of circulating tumour cells, extracellular vesicles and their microRNA content, as well as cellular and soluble immunological and inflammation- related blood markers for prostate cancer diagnosis, prognosis and prediction of therapy response is discussed. A special emphasis is placed on markers predicting response to radiotherapy and radiotherapy-related late side effects.

MiRNAs and radical prostatectomy: Current data, bioinformatic analysis and utility as predictors of tumour relapse

BACKGROUND

Studies of microRNAs (miRNAs) and genes have particular interest for cancer biology and medicine due to the discovery of new therapeutic targets and markers. These studies are extensively influenced by anticancer therapy, as miRNAs interfere with the therapy's efficacy in prostate cancer (PCa).

OBJECTIVES

In this article, we summarise the available data on the influence of radical prostatectomy (RP) and biochemical recurrence on miRNA expression.

MATERIALS AND METHODS

Molecular targets of these miRNAs, as well as the reciprocal relations between different miRNAs and their targets, were studied using the DIANA, STRING and TransmiR databases. Special attention was dedicated to the mechanisms of PCa development, miRNA, and associated genes as tumour development mediators.

RESULTS AND DISCUSSION

Combined analysis of the databases and available literature indicates that expression of four miRNAs that are associated with prostate cancer relapse and alter their expression after RP, combined with genes that closely interact with selected miRNAs, has high potential for the prediction of PCa relapse after RP. PCa tissues and biofluids, both immediately after RP for diagnostics/prognostics and in long-term (relapse) monitoring, may be used as sources of these miRNAs.

CONCLUSION

An overview of the usefulness of published data and bioinformatics resources looking for diagnostic markers and molecular targets is presented in this article. The selected miRNA and gene panels have good potential as prognostic and PCa relapse markers after RP and likely could also serve as markers for therapeutic efficiency on a broader scale.

miRNAs as Therapeutic Tools and Biomarkers for Prostate Cancer

Prostate cancer (PCa) is the fifth cause of tumor-related deaths in man worldwide. Despite the considerable improvement in the clinical management of PCa, several limitations emerged both in the screening for early diagnosis and in the medical treatment. The use of prostate-specific antigen (PSA)-based screening resulted in patients' overtreatment and the standard therapy of patients suffering from locally advanced/metastatic tumors (e.g., radical prostatectomy, radiotherapy, and androgen deprivation therapy) showed time-limited efficacy with patients undergoing progression toward the lethal metastatic castration-resistant PCa (mCRPC). Although valuable alternative therapeutic options have been recently proposed (e.g., docetaxel, cabazitaxel, abiraterone, enzalutamide, and sipuleucel-T), mCRPC remains incurable. Based on this background, there is an urgent need to identify new and more accurate prostate-specific biomarkers for PCa diagnosis and prognosis and to develop innovative medical approaches to counteract mCRPC. In this context, microRNA (miRNAs) emerged as potential biomarkers in prostate tissues and biological fluids and appeared to be promising therapeutic targets/tools for cancer therapy. Here we overview the recent literature and summarize the achievements of using miRNAs as biomarkers and therapeutic targets/tools for fighting PCa.

Liquid Biopsies: Applications for Cancer Diagnosis and Monitoring

The minimally-or non-invasive detection of circulating tumor-derived components in biofluids, such as blood, liquid biopsy is a revolutionary approach with significant potential for the management of cancer. Genomic and transcriptomic alterations can be accurately detected through liquid biopsies, which provide a more comprehensive characterization of the heterogeneous tumor profile than tissue biopsies alone. Liquid biopsies could assist diagnosis, prognosis, and treatment selection, and hold great potential to complement current surveilling strategies to monitor disease evolution and treatment response in real-time. In particular, these are able to detect minimal residual disease, to predict progression, and to identify mechanisms of resistance, allowing to re-orient treatment strategies in a timelier manner. In this review we gathered current knowledge regarding the role and potential of liquid biopsies for the diagnosis and follow-up of cancer patients. The presented findings emphasize the strengths of liquid biopsies, revealing their chance of improving the diagnosis and monitoring of several tumor types in the near future. However, despite growing evidence supporting their value as a management tool in oncology, some limitations still need to be overcome for their implementation in the routine clinical setting.

Radiation Response in the Tumour Microenvironment: Predictive Biomarkers and Future Perspectives

Radiotherapy (RT) is a primary treatment modality for a number of cancers, offering potentially curative outcomes. Despite its success, tumour cells can become resistant to RT, leading to disease recurrence. Components of the tumour microenvironment (TME) likely play an integral role in managing RT success or failure including infiltrating immune cells, the tumour vasculature and stroma. Furthermore, genomic profiling of the TME could identify predictive biomarkers or gene signatures indicative of RT response. In this review, we will discuss proposed mechanisms of radioresistance within the TME, biomarkers that may predict RT outcomes, and future perspectives on radiation treatment in the era of personalised medicine.

The Influence of Radical Prostatectomy on the Expression of Cell-Free MiRNA

MiRNAs of blood and urine have been shown to represent a convenient source of biomarkers for prostate cancer (PCa) diagnosis and assessment of the therapy effectiveness due to their high stability and representation and the low invasiveness of sample collection. Here, we studied the influence of radical prostatectomy (RP) on the expression of 12 cell-free miRNAs previously shown as potential markers of PCa (i.e., miR-19b, miR-22, miR-92a, miR-378, miR-425, miR-30e, miR-31, miR-125b, miR-200b, miR-205, miR-375 and miR-660). The relative expression of the miRNAs combined into 31 paired ratios was evaluated in the urine extracellular vesicles (EVs), clarified urine (CU) and blood plasma of healthy donors, pre- and post-RP samples of PCa patients. Nineteen miRNA ratios based on combinations of ten of the miRNAs (miR-19b, miR-30e, miR-31, miR-125b, miR-200b, miR-205, miR-375, miR-378, miR-425, and miR-660) were altered by RP. The comparative expression analysis of the cell-free miRNA ratios between healthy donors and PCa patients revealed miR-125b/miR-30e and miR-375/miR-30e as potential markers for evaluating therapeutic efficacy. MiR-378/miR-19b, miR-425/miR-19b, miR-200/miR-30e, miR-660/miR-30e, and miR-205/miR-30e had minor prognostic value but could be used to increase the steadiness of the diagnostic system. The urine EVs had the highest potential as a source of markers.

MiR-93/miR-375: Diagnostic Potential, Aggressiveness Correlation and Common Target Genes in Prostate Cancer

Dysregulation of miRNAs has a fundamental role in the initiation, development and progression of prostate cancer (PCa). The potential of miRNA in gene therapy and diagnostic applications is well documented. To further improve miRNAs' ability to distinguish between PCa and benign prostatic hyperplasia (BPH) patients, nine miRNA (-21, -27b, -93, -141, -205, -221, -182, -375 and let-7a) with the highest reported differentiation power were chosen and for the first time used in comparative studies of serum and prostate tissue samples. Spearman correlations and response operating characteristic (ROC) analyses were applied to assess the capability of the miRNAs present in serum to discriminate between PCa and BPH patients. The present study clearly demonstrates that miR-93 and miR-375 could be taken into consideration as single blood-based non-invasive molecules to distinguish PCa from BPH patients. We indicate that these two miRNAs have six common, PCa-related, target genes (CCND2, MAP3K2, MXI1, PAFAH1B1, YOD1, ZFYVE26) that share the molecular function of protein binding (GO:0005515 term). A high diagnostic value of the new serum derived miR-182 (AUC = 0.881, 95% confidence interval, CI = 0.816-0.946, p < 0.0001, sensitivity and specificity were 85% and 79%, respectively) is also described.

Circulating cell-free nucleic acids as prognostic and therapy predictive tools for metastatic castrate-resistant prostate cancer

Metastatic castrate-resistant prostate cancer remains a disease hard to cure, and for this reason predictive tools to monitor disease progression and therapy response are an urgent need. In this respect, liquid biopsy on circulating cell-free nucleic acids represents an interesting strategy based on robust data. The low invasiveness and the possibility to target circulating cell-free tumor deoxyribonucleic acid underline the high specificity, sensitivity and clinical usability of the technique. Moreover, it has been observed that the cell-free tumor deoxyribonucleic acid of metastatic castrate-resistant prostate cancer patients can be representative of the tumor heterogeneity. Cell-free tumor deoxyribonucleic acids express the same behaviors as mutations: Variation in gene copy number or the methylation rate of the tumor tissue. Recently, circulating cell-free ribonucleic acid molecules have emerged as interesting markers to stratify the disease. Due to high-throughput technologies, liquid biopsy on circulating cell-free nucleic acids will soon be utilized in the clinical management of metastatic castrate-resistant prostate cancer patients.

microRNAs identified in prostate cancer: Correlative studies on response to ionizing radiation

As the most frequently diagnosed non-skin cancer in men and a leading cause of cancer-related death, understanding the molecular mechanisms that drive treatment resistance in prostate cancer poses a significant clinical need. Radiotherapy is one of the most widely used treatments for prostate cancer, along with surgery, hormone therapy, and chemotherapy. However, inherent radioresistance of tumor cells can reduce local control and ultimately lead to poor patient outcomes, such as recurrence, metastasis and death. The underlying mechanisms of radioresistance have not been fully elucidated, but it has been suggested that miRNAs play a critical role. miRNAs are small non-coding RNAs that regulate gene expression in every signaling pathway of the cell, with one miRNA often having multiple targets. By fine-tuning gene expression, miRNAs are important players in modulating DNA damage response, cell death, tumor aggression and the tumor microenvironment, and can ultimately affect a tumor's response to radiotherapy. Furthermore, much interest has focused on miRNAs found in biofluids and their potential utility in various clinical applications. In this review, we summarize the current knowledge on miRNA deregulation after irradiation and the associated functional outcomes, with a focus on prostate cancer. In addition, we discuss the utility of circulating miRNAs as non-invasive biomarkers to diagnose, predict response to treatment, and prognosticate patient outcomes.

Increased estrogen levels altered microRNA expression in prostate and plasma of rats dosed with sex hormones

BACKGROUND

Elevated estrogen (E) levels caused by aging or exposure to endocrine disrupting chemicals are related to prostate disease development. Sixty to seventy percent of prostate cancer or benign prostatic hyperplasia patients are over the age of 65, while prostatitis is likely to occur in men under 45 years. MicroRNAs currently represent a class of distinctive biological indicators to be used for clinical disease diagnosis and treatment monitoring. This study aims to identify microRNAs that could serve as potential biomarkers for prostate disorders induced by elevated E levels according to their altered expression in prostate or plasma.

MATERIALS AND METHODS

Groups of Sprague Dawley rats (offspring) were dosed with estradiol benzoate (EB) on postnatal days 1, 3, and 5, and subcutaneously implanted with tubes containing testosterone (T)/E on postnatal day 90. Expression levels of prostate and plasma microRNAs were evaluated using microRNA microarray and validated via qRT-PCR. The expression levels of the potential targeted genes of a set of identified microRNAs were also examined by qRT-PCR.

RESULTS

Postnatal administration of EB, T, and E elevated serum E levels with decreased serum T levels in rats. Chronic inflammation was observed in the dorsolateral prostate. Significant changes in expression levels of several microRNAs (rno-miR-146-5p, rno-miR-329-3p, and rno-miR-126a-3p) in the dorsolateral prostate and of a microRNA (rno-miR-329-3p) in the plasma were found in the dosed rats. The target gene expression levels of the altered microRNAs also changed accordingly.

CONCLUSION

Chronic inflammation in the dorsolateral prostate of rats dosed with EB, T, and E resulted in deregulated expression in a set of microRNAs whose target genes were related to tumor growth or abnormal proliferation. Our findings suggest the identified microRNAs and their target genes the potential use as biomarkers to predict prostate cancer development. Validation using human samples is warranted.

Circulating miR-141 and miR-375 are associated with treatment outcome in metastatic castration resistant prostate cancer

Metastatic castration resistant prostate cancer (mCRPC) is associated with high mortality, where monitoring of disease activity is still a major clinical challenge. The role of microRNAs (miRs) has been widely investigated in prostate cancer with both diagnostic and prognostic potential. The aim of this study was to investigate the relationship between circulating miRs and treatment outcome in mCRPC patients. The relative expression of five miRs (miR-93-5p, -125b-1-5p, -141-3p, -221-3p, and miR-375-3p) was investigated in plasma samples from 84 mCRPC patients; 40 patients were treated with docetaxel (DOC cohort) and 44 patients with abiraterone (ABI cohort). Blood was sampled at baseline before treatment start and at radiological progression. The plasma levels of four miRs; miR-93-5p, -141-3p, -221-3p, and miR-375-3p decreased significantly after treatment initiation in patients receiving docetaxel, and for miR-141-3p and miR-375-3p the level increased again at the time of radiological progression. In the patients treated with abiraterone, the plasma level of miR-221-3p likewise decreased significantly after the first treatment cycle. High baseline levels of both miR-141-3p and miR-375-3p were significantly associated with a shorter time to radiological progression in both cohorts. Additionally, high baseline levels of miR-141-3p and miR-221-3p were significantly associated with a shorter overall survival (OS) in the ABI cohort, while high levels of miR-141-3p and miR-375-3p were significantly associated with shorter OS in the DOC cohort. Plasma levels of miR-141-3p and miR-375-3p may predict time to progression in mCRPC patients treated with docetaxel or abiraterone. The clinical impact of these findings is dependent on validation in larger cohorts.

Molecular Composition of Genomic TMPRSS2-ERG Rearrangements in Prostate Cancer

There is increasing interest in the use of cell-free circulating tumor DNA (ctDNA) as a serum marker for therapy assessment in prostate cancer patients. Prostate cancer is characterized by relatively low numbers of mutations, and, in contrast to many other common epithelial cancers, commercially available single nucleotide mutation assays for quantification of ctDNA are insufficient for therapy assessment in this disease. However, prostate cancer shares some similarity with translocation-affected mesenchymal tumors (e.g., leukemia and Ewing sarcoma), which are common in pediatric oncology, where chromosomal translocations are used as biomarkers for quantification of the tumor burden. Approximately 50% of prostate cancers carry a chromosomal translocation resulting in generation of the TMPRSS2-ERG fusion gene, which is unique to the tumor cells of each individual patient because of variability in the fusion breakpoint sites. In the present study, we examined the structural preconditions for TMPRSS2-ERG fusion sites in comparison with mesenchymal tumors in pediatric patients to determine whether the sequence composition is suitable for the establishment of tumor-specific quantification assays in prostate cancer patients. Genomic repeat elements represent potential obstacles to establishment of quantification assays, and we found similar proportions of repeat elements at fusion sites in prostate cancer to those reported for mesenchymal tumors, where genomic fusion sequences are established as biomarkers. Our data support the development of the TMPRSS2-ERG fusion gene as a noninvasive tumor marker for therapy assessment, risk stratification, and relapse detection to improve personalized therapy strategies for patients with prostate cancer.

MicroRNA biogenesis, gene silencing mechanisms and role in breast, ovarian and prostate cancer

Micro-ribonucleic acids (miRNAs) are important class of short regulatory RNA molecules involved in regulation of several essential biological processes. In addition to Dicer and Drosha, over the past few years several other gene products are discovered that regulates miRNA biogenesis pathways. Similarly, various models of molecular mechanisms underlying miRNA mediated gene silencing have been uncovered through which miRNA contribute in diverse physiological and pathological processes. Dysregulated miRNA expression has been reported in many cancers manifesting tumor suppressive or oncogenic role. In this review, critical overview of recent findings in miRNA biogenesis, silencing mechanisms and specifically the role of miRNA in breast, ovarian and prostate cancer will be described. Recent advancements in miRNA research summarized in this review will enhance the molecular understanding of miRNA biogenesis and mechanism of action. Also, role of miRNAs in pathogenesis of breast, ovarian and prostate cancer will provide the insights for the use of miRNAs as biomarker or therapeutic agents for the cancers.

Known epigenetic biomarkers for prostate cancer detection and management: exploring the potential of blood-based liquid biopsies

INTRODUCTION

Although prostate cancer (PCa) stands as an important cause of cancer-related deaths, a sizeable proportion of diagnosed cases are clinically insignificant. Hence, novel and more specific biomarkers to identify clinically significant PCa are needed. Liquid biopsies offer the potential to accurately identify cancer markers, including PCa. Epigenetic biomarkers such as cell-free DNA and circulating RNAs have emerged as minimally invasive cancer markers. Areas covered: Herein, we provide an overview of epigenetic biomarkers current state based on a comprehensive review of the relevant literature in blood-based liquid biopsies and challenges/limitations of this new and growing field of cancer biomarkers. Expert opinion: The epigenetic-based biomarkers characteristics make them attractive to the clinics and their minimally invasive assessment are a promising opportunity for PCa detection/management. The main limitations are the lack of robust validation studies and integrated approaches. Future studies would benefit from a change in focus to a 'selected PCa detection'.

Circulating miRNAs in localized/locally advanced prostate cancer patients after radical prostatectomy and radiotherapy

BACKGROUND

Overtreatment is a well-known clinical challenge in local prostate cancer (PCa). Although risk assessment models have contributed to a better stratification of patients with local PCa, a tailored management is still in its infancy. Over the last few decades, microRNAs (miRNAs) have shown promising results as biomarkers in PCa. The aim of this study was to investigate circulating miRNAs after management of local PCa.

METHODS

The relative expression of four miRNAs (miRNA-21, -93, -125b, and miRNA-221) was assessed in plasma from 149 newly diagnosed patients with local or locally advanced PCa. Real-time polymerase chain reaction was used for analysis. A baseline sample at time of diagnosis and a follow-up sample after 6 months were assessed. The patients were grouped in an interventional cohort (radical prostatectomy, curative intent radiotherapy, or androgen-deprivation therapy alone) and an observational cohort (watchful waiting or active surveillance).

RESULTS

In the interventional cohort, levels of both miRNA-93 and miRNA-221 were significantly lower in the follow-up samples compared to baseline z = -2.738, P = 0.006, and z = -4.498, P < 0.001, respectively. The same observation was recorded for miRNA-125b in the observational cohort (z = -2.656, P = 0.008). Both miRNA-125b and miRNA-221 were correlated with risk assessment r = 0.23, P = 0.015, and r = 0.203, P = 0.016 respectively, while miRNA-93 showed tendency to significant correlation with the prostatectomy Gleason score (r = 0.276, P = 0.0576).

CONCLUSIONS

The current results indicate a possible role of miRNA-93 and miRNA-221 in disease monitoring in localized and locally advanced PCa. Larger studies are warranted to assess the clinical impact of these biomarkers.