miR-145 suppress the androgen receptor in prostate cancer cells and correlates to prostate cancer prognosis

Liquid biomarkers in prostate cancer: recent advancements and future directions

PURPOSE OF REVIEW

Traditional diagnostic approaches of prostate cancer like PSA are limited by high false-positive rates and insufficient capture of tumour heterogeneity, necessitating the development of more precise tools. This review examines the latest advancements in liquid biomarkers for prostate cancer, focusing on their potential to refine diagnostic accuracy and monitor disease progression.

RECENT FINDINGS

Liquid biomarkers have gained prominence because of their minimally invasive nature and ability to reflect the molecular characteristics of prostate cancer. Circulating tumour cells provide insight into tumour cell dissemination and are indicative of aggressive disease phenotypes, with single-cell analyses revealing genomic instability and treatment resistance. Circulating tumour DNA offers real-time tumour genomic information, aiding in treatment decision-making in advanced prostate cancer, where it has been associated with clinical progression. MicroRNAs act as oncogenes or tumour suppressors and exhibit diagnostic and prognostic potential; however, their clinical utility is constrained by the lack of consistent validation. Extracellular vesicles contain tumour-derived biomolecules, with specific proteins demonstrating prognostic relevance. Applications of these markers to urinary testing have been demonstrated.

SUMMARY

Liquid biomarkers show potential in refining prostate cancer management. Future research should aim to integrate these biomarkers into a cohesive framework in line with precision medicine principles.

Epigenetic regulation of androgen dependent and independent prostate cancer

Prostate cancer is one of the most common malignancies among men worldwide. Besides genetic alterations, epigenetic modulations including DNA methylation, histone modifications and miRNA mediated alteration of gene expression are the key driving forces for the prostate tumor development and cancer progression. Aberrant expression and/or the activity of the epigenetic modifiers/enzymes, results in aberrant expression of genes involved in DNA repair, cell cycle regulation, cell adhesion, apoptosis, autophagy, tumor suppression and hormone response and thereby disease progression. Altered epigenome is associated with prostate cancer recurrence, progression, aggressiveness and transition from androgen-dependent to androgen-independent phenotype. These epigenetic modifications are reversible and various compounds/drugs targeting the epigenetic enzymes have been developed that are effective in cancer treatment. This chapter focuses on the epigenetic alterations in prostate cancer initiation and progression, listing different epigenetic biomarkers for diagnosis and prognosis of the disease and their potential as therapeutic targets. This chapter also summarizes different epigenetic drugs approved for prostate cancer therapy and the drugs available for clinical trials.

Radiotherapy Metastatic Prostate Cancer Cell Lines Treated with Gold Nanorods Modulate miRNA Signatures

MicroRNA (miRNA) modulation has been identified as a promising strategy for improving the response of human prostate cancer (PCa) to radiotherapy (RT). Studies have shown that mimics or inhibitors of miRNAs could modulate the sensitivity of PCa cells to RT. In addition, pegylated gold nanoparticles have been studied as a therapeutic approach to treat PCa cells and/or vehicles for carrying miRNAs to the inside of cells. Therefore, we evaluated the capacity of hypofractionated RT and pegylated gold nanorods (AuNPr-PEG) to modulate the miRNA signature on PCa cells. Thus, RT-qPCR was used to analyze miRNA-95, miRNA-106-5p, miRNA-145-5p, and miRNA-541-3p on three human metastatic prostate cell lines (PC3, DU145, and LNCaP) and one human prostate epithelial cell line (HprEpiC, a non-tumor cell line) with and without treatment. Our results showed that miRNA expression levels depend on cell type and the treatment combination applied using RT and AuNPr-PEG. In addition, cells pre-treated with AuNPr-PEG and submitted to 2.5 Gy per day for 3 days decreased the expression levels of miRNA-95, miRNA-106, miRNA-145, and miRNA-541-3p. In conclusion, PCa patients submitted to hypofractionated RT could receive personalized treatment based on their metastatic cellular miRNA signature, and AuNPr-PEG could be used to increase metastatic cell radiosensitivity.

Functional In Vivo Screening Identifies microRNAs Regulating Metastatic Dissemination of Prostate Cancer Cells to Bone Marrow

Distant metastasis is the major cause of cancer-related deaths in men with prostate cancer (PCa). An in vivo functional screen was used to identify microRNAs (miRNAs) regulating metastatic dissemination of PCa cells. PC3 cells transduced with pooled miRZiP™ lentivirus library (anti-miRNAs) were injected intraprostatic to 13 NSG mice followed by targeted barcode/anti-miR sequencing. PCa cells in the primary tumours showed a homogenous pattern of anti-miRNAs, but different anti-miRNAs were enriched in liver, lung, and bone marrow, with anti-miR-379 highly enriched in the latter. The bone metastasis-promoting phenotype induced by decreased miR-379 levels was also confirmed in a less metastatic PCa cell line, 22Rv1, where all mice injected intracardially with anti-miR-379-22Rv1 cells developed bone metastases. The levels of miR-379 were found to be lower in bone metastases compared to primary tumours and non-cancerous prostatic tissue in a patient cohort. In vitro functional studies suggested that the mechanism of action was that reduced levels of miR-379 gave an increased colony formation capacity in conditions mimicking the bone microenvironment. In conclusion, our data suggest that specific miRNAs affect the establishment of primary tumours and metastatic dissemination, with a loss of miR-379 promoting metastases in bone.

Plasmatic MicroRNAs and Treatment Outcomes of Patients with Metastatic Castration-Resistant Prostate Cancer: A Hospital-Based Cohort Study and In Silico Analysis

Prostate cancer (PCa) is one of the most common malignancies among men worldwide. Inevitably, all advanced PCa patients develop metastatic castration-resistant prostate cancer (mCRPC), an aggressive phase of the disease. Treating mCRPC is challenging, and prognostic tools are needed for disease management. MicroRNA (miRNA) deregulation has been reported in PCa, constituting potential non-invasive prognostic biomarkers. As such, this study aimed to evaluate the prognostic potential of nine miRNAs in the liquid biopsies (plasma) of mCRPC patients treated with second-generation androgen receptor axis-targeted (ARAT) agents, abiraterone acetate (AbA) and enzalutamide (ENZ). Low expression levels of miR-16-5p and miR-145-5p in mCRPC patients treated with AbA were significantly associated with lower progression-free survival (PFS). The two miRNAs were the only predictors of the risk of disease progression in AbA-stratified analyses. Low miR-20a-5p levels in mCRPC patients with Gleason scores of <8 were associated with worse overall survival (OS). The transcript seems to predict the risk of death regardless of the ARAT agent. According to the in silico analyses, miR-16-5p, miR-145-5p, and miR-20a-5p seem to be implicated in several processes, namely, cell cycle, proliferation, migration, survival, metabolism, and angiogenesis, suggesting an epigenetic mechanism related to treatment outcome. These miRNAs may represent attractive prognostic tools to be used in mCRPC management, as well as a step further in the identification of new potential therapeutic targets, to use in combination with ARAT for an improved treatment outcome. Despite the promising results, real-world validation is necessary.

Investigating microRNA Profiles in Prostate Cancer Bone Metastases and Functional Effects of microRNA-23c and microRNA-4328

MicroRNAs (miRNAs) are aberrantly expressed in prostate cancer (PC), but comprehensive knowledge about their levels and function in metastatic PC is lacking. Here, we explored the differential expression of miRNA profiles during PC progression to bone metastasis, and further focused on the downregulation of miRNA-23c and -4328 and their impact on PC growth in experimental models. Using microarray screening, the levels of 1510 miRNAs were compared between bone metastases (n = 14), localized PC (n = 7) and benign prostate tissue (n = 7). Differentially expressed miRNAs (n = 4 increased and n = 75 decreased, p < 0.05) were identified, of which miRNA-1, -23c, -143-3p, -143-5p, -145-3p, -205-5p, -221-3p, -222-3p and -4328 showed consistent downregulation during disease progression (benign > localized PC > bone metastases). The downregulation of miRNA-23c and -4328 was confirmed by reverse transcription and quantitative polymerase chain reaction analysis of 67 metastasis, 12 localized PC and 12 benign prostate tissue samples. The stable overexpression of miRNA-23c and -4328 in the 22Rv1 and PC-3 cell lines resulted in reduced PC cell growth in vitro, and in the secretion of high levels of miRNA-23c (but not -4328) in extracellular vesicles. However, no tumor suppressive effects were observed from miRNA-23c overexpression in PC-3 cells subcutaneously grown in mice. In conclusion, bone metastases display a profound reduction of miRNA levels compared to localized PC and benign disease. The downregulation of those miRNAs, including miRNA-23c and -4328, may lead to a loss of tumor suppressive effects and provide biomarker and therapeutic possibilities that deserve to be further explored.

Fibronectin Modulates the Expression of miRNAs in Prostate Cancer Cell Lines

Prostate cancer (PCa) is a significant cause of cancer-related deaths among men and companion animals, such as dogs. However, despite its high mortality and incidence rates, the molecular mechanisms underlying this disease remain to be fully elucidated. Among the many factors involved in prostate carcinogenesis, the extracellular matrix (ECM) plays a crucial role. This ECM in the prostate is composed mainly of collagen fibers, reticular fibers, elastic fibers, proteoglycans and glycoproteins, such as fibronectin. Fibronectin is a glycoprotein whose dysregulation has been implicated in the development of multiple types of cancer, and it has been associated with cell migration, invasion, and metastasis. Furthermore, our research group has previously shown that fibronectin induces transcriptional changes by modulating the expression of protein coding genes in LNCaP cells. However, potential changes at the post-transcriptional level are still not well understood. This study investigated the impact of exposure to fibronectin on the expression of a key class of regulatory RNAs, the microRNAs (miRNAs), in prostate cancer cell lines LNCaP and PC-3. Five mammalian miRNAs (miR-21, miR-29b, miR-125b, miR-221, and miR-222) were differentially expressed after fibronectin exposure in prostate cell lines. The expression profile of hundreds of mRNAs predicted to be targeted by these miRNAs was analyzed using publicly available RNA-Sequencing data (GSE64025, GSE68645, GSE29155). Also, protein-protein interaction networks and enrichment analysis were performed to gain insights into miRNA biological functions. Altogether, these functional analyzes revealed that fibronectin exposure impacts the expression of miRNAs potentially involved in PCa causing changes in critical signaling pathways such as PI3K-AKT, and response to cell division, death, proliferation, and migration. The relationship here demonstrated between fibronectin exposure and altered miRNA expression improves the comprehension of PCa in both men and other animals, such as dogs, which naturally develop prostate cancer.

miRNAs as molecular biomarkers for prostate cancer

MicroRNAs (miRNAs) are short noncoding RNA able to regulate specific mRNA stability, thus influencing target gene expression. Disrupted levels of several miRNA have been associated with prostate cancer, the leading cause of cancer death among men and the fifth leading cause of death worldwide. Here, we investigated whether miR-145, miR-148, and miR-185 circulating levels in plasma could be used as molecular biomarkers, to allow distinguishing between individuals with benign prostatic hyperplasia, precancerous lesion, and prostate cancer. In this study, we recruited 170 urological clinic patients with suspected prostate cancer who underwent prostate biopsy. Total RNA was isolated from plasma, and TaqMan MicroRNA assays were used to analyze miR-145, miR-185, and miR-148 expression. First, differential miRNA expression among patient groups was evaluated. Then, miRNA levels were combined with clinical assessment outcomes, including results from invasive tests, using multivariate analysis to examine their ability in discriminating among the three patient groups. Our results suggest that miRNA is a promising molecular tool for clinical management of at-risk patients.

miR-145-5p Inhibits Neuroendocrine Differentiation and Tumor Growth by Regulating the SOX11/MYCN Axis in Prostate cancer

Recent studies have shown that the downregulation of miR-145-5p in prostate cancer (PCa) is significantly associated with poor differentiation and prognosis. We aimed to investigate the biological role of miR-145-5p in the neuroendocrine differentiation (NED) of PCa. In this study, TheCancer Genome Atlas was used to identify the association of miR-145-5p with PCa. The functions of miR-145-5p were evaluated using the Cell Counting Kit-8 (CCK-8) assay and cell cycle analysis. We validated changes in cell cycle control by testing the expression of cyclin-related genes by western blot. The luciferase reporter assay was performed to test miR-145-5p-targeting genes and direct transcriptional targets of SOX11. The expression of miR-145-5p was found to be significantly downregulated in castration-resistant PCa, and this was correlated with higher Gleason score and prostate-specific antigen. We confirmed these results using PC3 and LNCaP cell lines depicted a gradual decline of miR-145-5p while the cells were cultured under androgen depletion conditions. Moreover, the knockdown of miR-145-5p significantly promoted NED and proliferation of LNCaP cells, whereas overexpression of miR-145-5p significantly inhibited NED and proliferation of LNCaP cells. Mechanistically, we found that SOX11 was a direct target of miR-145-5p, which regulates MYCN might mediate induction of NED and proliferation of LNCaP cells. Furthermore, knockdown of miR-145-5p promoted tumor growth in vivo. Our findings suggest that miR-145-5p can inhibit NED and tumor growth by targeting SOX11, which regulates the expression of MYCN, and that this could be a novel therapeutic strategy for preventing the progression of PCa.

Role of miRNA-145, 148, and 185 and Stem Cells in Prostate Cancer

MicroRNAs (miRNAs) are small non-coding RNA molecules that play a role in cancer linked to the regulation of important cellular processes and pathways involving tumorigenesis, cell proliferation, differentiation, and apoptosis. A lot of human miRNA sequences have been identified which are linked to cancer pathogenesis. MicroRNAs, in prostate cancer (PC), play a relevant role as biomarkers, show a specific profile, and have been used as therapeutic targets. Prostate cancer (PC) is the most frequently diagnosed cancer in men. Clinical diagnoses among the gold standards for PC diagnosis and monitoring are prostate-specific antigen (PSA) testing, digital rectal examination, and prostate needle biopsies. PSA screening still has a large grey area of patients, which leads to overdiagnosis. Therefore, new biomarkers are needed to improve existing diagnostic tools. The miRNA expression profiles from tumour versus normal tissues are helpful and exhibit significant differences not only between cancerous and non-cancerous tissues, but also between different cancer types and subtypes. In this review, we focus on the role of miRNAs-145, 148, and 185 and their correlation with stem cells in prostate cancer pathogenesis. MiR-145, by modulating multiple oncogenes, regulates different cellular processes in PC, which are involved in the transition from localised to metastatic disease. MiR-148 is downregulated in high-grade tumours, suggesting that the miR-148-3 family might act as tumour suppressors in PC as a potential biomarker for detecting this disease. MiR-185 regulation is still unclear in being able to regulate tumour processes in PC. Nevertheless, other authors confirm the role of this miRNA as a tumour suppressor, suggesting its potential use as a suitable biomarker in disease prognosis. These three miRNAs are all involved in the regulation of prostate cancer stem cell behaviour (PCSCs). Within this contest, PCSCs are often involved in the onset of chemo-resistance in PC, therefore strategies for targeting this subset of cells are strongly required to control the disease. Hence, the relationship between these two players is interesting and important in prostate cancer pathogenesis and in PCSC stemness regulation, in the attempt to pave the way for novel therapeutic targets in prostate cancer.

The Role of Androgen Receptor and microRNA Interactions in Androgen-Dependent Diseases

The androgen receptor (AR) is a member of the steroid hormone receptor family of nuclear transcription factors. It is present in the primary/secondary sexual organs, kidneys, skeletal muscles, adrenal glands, skin, nervous system, and breast. Abnormal AR functioning has been identified in numerous diseases, specifically in prostate cancer (PCa). Interestingly, recent studies have indicated a relationship between the AR and microRNA (miRNA) crosstalk and cancer progression. MiRNAs are small, endogenous, non-coding molecules that are involved in crucial cellular processes, such as proliferation, apoptosis, or differentiation. On the one hand, AR may be responsible for the downregulation or upregulation of specific miRNA, while on the other hand, AR is often a target of miRNAs due to their regulatory function on AR gene expression. A deeper understanding of the AR–miRNA interactions may contribute to the development of better diagnostic tools as well as to providing new therapeutic approaches. While most studies usually focus on the role of miRNAs and AR in PCa, in this review, we go beyond PCa and provide insight into the most recent discoveries about the interplay between AR and miRNAs, as well as about other AR-associated and AR-independent diseases.

MicroRNAs as biomarkers for prostate cancer prognosis: a systematic review and a systematic reanalysis of public data

Background

Reliable prognostic biomarkers to distinguish indolent from aggressive prostate cancer (PCa) are lacking. Many studies investigated microRNAs (miRs) as PCa prognostic biomarkers, often reporting inconsistent findings. We present a systematic review of these; also systematic reanalysis of public miR-profile datasets to identify tissue-derived miRs prognostic of biochemical recurrence (BCR) in patients undergoing radical prostatectomy.

Methods

Independent PubMed searches were performed for relevant articles from January 2007 to December 2019. For the review, 128 studies were included. Pooled-hazard-ratios (HRs) for miRs in multiple studies were calculated using a random-effects model (REM). For the reanalysis, five studies were included and Cox proportional-hazard models, testing miR association with BCR, performed for miRs profiled in all.

Results

Systematic review identified 120 miRs as prognostic. Five (let-7b-5p, miR-145-5p, miR152-3p, miR-195-5p, miR-224-5p) were consistently associated with progression in multiple cohorts/studies. In the reanalysis, ten (let-7a-5p, miR-148a-3p, miR-203a-3p, miR-26b-5p, miR30a-3p, miR-30c-5p, miR-30e-3p, miR-374a-5p, miR-425-3p, miR-582-5p) were significantly prognostic of BCR. Of these, miR-148a-3p (HR = 0.80/95% CI = 0.68-0.94) and miR-582-5p (HR = 0.73/95% CI = 0.61-0.87) were also reported in prior publication(s) in the review.

Conclusions

Fifteen miRs were consistently associated with disease progression in multiple publications or datasets. Further research into their biological roles is warranted to support investigations into their performance as prognostic PCa biomarkers.

Interaction between Non-Coding RNAs and Androgen Receptor with an Especial Focus on Prostate Cancer

The androgen receptor (AR) is a member of the nuclear receptor superfamily and has three functional domains, namely the N-terminal, DNA binding, and C-terminal domain. The N-terminal domain harbors potent transactivation functions, whereas the C-terminal domain binds to androgens and antiandrogens used to treat prostate cancer. AR has genomic activity being DNA binding-dependent or through interaction with other DNA-bound transcription factors, as well as a number of non-genomic, non-canonical functions, such as the activation of the ERK, AKT, and MAPK pathways. A bulk of evidence indicates that non-coding RNAs have functional interactions with AR. This type of interaction is implicated in the pathogenesis of human malignancies, particularly prostate cancer. In the current review, we summarize the available data on the role of microRNAs, long non-coding RNAs, and circular RNAs on the expression of AR and modulation of AR signaling, as well as the effects of AR on their expression. Recognition of the complicated interaction between non-coding RNAs and AR has practical importance in the design of novel treatment options, as well as modulation of response to conventional therapeutics.

Wnt/β-catenin signal transduction pathway in prostate cancer and associated drug resistance

Globally, prostate cancer ranks second in cancer burden of the men. It occurs more frequently in black men compared to white or Asian men. Usually, high rates exist for men aged 60 and above. In this review, we focus on the Wnt/β-catenin signal transduction pathway in prostate cancer since many studies have reported that β-catenin can function as an oncogene and is important in Wnt signaling. We also relate its expression to the androgen receptor and MMP-7 protein, both critical to prostate cancer pathogenesis. Some mutations in the androgen receptor also impact the androgen-β-catenin axis and hence, lead to the progression of prostate cancer. We have also reviewed MiRNAs that modulate this pathway in prostate cancer. Finally, we have summarized the impact of Wnt/β-catenin pathway proteins in the drug resistance of prostate cancer as it is a challenging facet of therapy development due to the complexity of signaling pathways interaction and cross-talk.

MiR-145 suppresses the motility of prostate cancer cells by targeting cadherin-2

Metastasis is the main cause of poor prognosis in the advanced prostate cancer in clinic. Accumulating evidences have proposed that cell motility greatly contributes to the multiple steps of the metastatic process. MicroRNA-145 (miR-145) has been found to be downregulated in prostate cancer and serve as a putative tumor suppressor via decrease of cell growth and augmentation of cell death; however, the effects and the underlying mechanisms of miR-145 in prostate cancer cell motility have not been completely clarified. In the current study, we first demonstrated that miR-145 exerted inhibitory effects on the aggressive phenotype of the prostate cancer cells. Based on the bioinformatics analysis of the putative target genes of miR-145, we further experimentally identified a novel mechanism of miR-145 suppressing the aggressive phenotype of prostate cancer cells via directly targeting cadherin-2 (CDH2) protein translation. Re-expression of CDH2 could rescue miR-145-triggered cell migration and invasion defects. Our results suggested that miR-145 suppressed the motility of prostate cancer cells via post-transcriptional downregulation of CDH2 expression, and miR-145-CDH2 pair might serve as a potential target for intervention of prostate cancer metastasis.

miRNAs and androgen deprivation therapy for prostate cancer

Androgen deprivation therapy (ADT) is mainly used for the treatment of advanced, metastatic or recurrent prostate cancer (PCa). However, patients progress to ADT resistance and castration-resistant prostate cancer (CRPC) with a poor prognosis. Reliable validated markers of ADT resistance with proven clinical utility are necessary for timely correction of the therapy as well as for improvement of patient quality of life. MiRNAs involved in the ADT response and CRPC development via multiple mechanisms may act as biomarkers for patient outcomes. Available data on miRNAs associated with the ADT response (resistance and sensitivity) are summarized and analyzed in the manuscript, including analyses using bioinformatics resources. Molecular targets of miRNAs, as well as reciprocal relations between miRNAs and their targets, were studied using different databases. Special attention was dedicated to the mechanisms of ADT resistance and CRPC development, including testosterone, PI3K-AKT, VEGF pathways and associated genes. Several different approaches can be used to search for miRNAs associated with the ADT response, each of which focuses on the associated set of miRNAs - potential markers of ADT. The intersection of these approaches and combined analysis allowed us to select the most promising miRNA markers of the ADT response. Meta-analysis of the current data indicated that the selected 5 miRNAs (miRNAs - 125b, miR-21, miR-23b, miR-27b and miR-221) and 14 genes are involved in the regulation of key processes of CRPC development and represent the most promising predictors of the ADT response, further demonstrating their potential in combination therapy for advanced PCa.

Androgen receptor variants: RNA-based mechanisms and therapeutic targets

Prostate cancer is the second leading cause of male cancer death in the United States. The androgen receptor (AR) transcription factor is a master regulator of normal glandular homeostasis in the prostate, as well as growth and survival of prostate cancer cells. Therefore, AR-targeted therapies are effective for improving overall survival of patients with advanced prostate cancer that is incurable by surgery or radiation. However, prostate cancer will inevitably progress on AR-targeted therapies to a castration-resistant prostate cancer (CRPC) phenotype that accounts for virtually all prostate cancer-specific death. mRNA transcript variants of the AR gene are expressed in CRPC cells and can be translated to produce AR variant (AR-V) proteins that function as ligand-independent, constitutively active transcription factors. AR-Vs are able to support growth of CRPC cells by promoting expression of AR target genes that are normally suppressed by AR-targeted therapies. Knowledge of mechanisms that govern expression of AR-Vs is incomplete. Studies have shown genomic rearrangements of the AR gene underlie expression of diverse AR-Vs in certain CRPC tumors, but post-transcriptional processes represent a broader regulatory mechanism for expression of AR-Vs in CRPC. This review focuses on alternative splicing, 3' end processing, miRNA-mediated mRNA repression, of AR and AR-V expression and the potential these mechanisms hold as therapeutic targets for CRPC.

Human Prostate Tissue MicroRNAs and Their Predicted Target Pathways Linked to Prostate Cancer Risk Factors

MicroRNAs are important in prostate cancer development, progression and metastasis. The aim of this study was to test microRNA expression profile in prostate tissue obtained from prostate cancer patients for associations with various prostate cancer related factors and to pinpoint the predicted target pathways for these microRNAs. Prostate tissue samples were obtained at prostatectomy from patients participating in a trial evaluating impact of pre-operative atorvastatin on serum prostate specific antigen (PSA) and Ki-67 expression in prostate tissue. Prostate tissue microRNA expression profiles were analyzed using OpenArray^® MicroRNA Panel. Pathway enrichment analyses were conducted for predicted target genes of microRNAs that correlated significantly with studied factors. Eight microRNAs correlated significantly with studied factors of patients after Bonferroni multiple testing correction. MiR-485-3p correlated with serum HDL-cholesterol levels. In atorvastatin-treated subjects, miR-34c-5p correlated with a change in serum PSA and miR-138-3p with a change in total cholesterol. In the placebo arm, both miR-576-3p and miR-550-3p correlated with HDL-cholesterol and miR-627 with PSA. In pathway analysis, these eight microRNAs related significantly to several pathways relevant to prostate cancer. This study brings new evidence from the expression of prostate tissue microRNAs and related pathways that may link risk factors to prostate cancer and pinpoint new therapeutic possibilities.

SChLAP1 promotes prostate cancer development through interacting with EZH2 to mediate promoter methylation modification of multiple miRNAs of chromosome 5 with a DNMT3a-feedback loop

This study aimed to investigate the mechanism of SChLAP1 (second chromosome locus associated with prostate-1) on microRNA expression in prostate cancer. Differential expression of lncRNAs and microRNA prostate cancer cells were predicted by informatics and confirmed by qRT-PCR. SChLAP1-interacting proteins were characterized by RNA pull-down combined with western blotting, which was verified using RIP and qPCR analysis. Then ChIP assay and DNA pull-down were used to validate the binding of DNMT3a and HEK27me3 with miRNA gene promoters. Target genes of miRNAs were bioinformatically predicted and validated by dual-luciferase reporter assays. The tumorigenicity of prostate cancer cells was assessed using the cancer cell line-based xenograft (CDX) model. We found that SChLAP1 expression was significantly elevated in prostate cancer tissues and cell lines, which was negatively correlated with miR-340 expression. SChLAP1 directly binds with EZH2 and repressed multiple miRNA expression on chromosome 5 including the miR-340-3p in prostate cancer cells through recruiting H3K27me3 to mediate promoter methylation modification of miR-340-5p/miR-143-3p/miR-145-5p to suppress gene transcription. Moreover, DNMT3a was one of the common target genes of miR-340-5p/miR-143-3p/miR-145-5p in prostate cancer cells. And SChLAP1/EZH2 could also promote prostate cancer tumor development via the interaction of microRNA-DNMT3a signaling pathways in xenograft nude mice. Altogether, our results suggest that SChLAP1 enhanced the proliferation, migration, and tumorigenicity of prostate cancer cells through interacting with EZH2 to recruit H2K27me3 and mediate promoter methylation modification of miR-340-5p/miR-143-3p/miR-145-5p with a DNMT3a-feedback loop.

MiRNA-145-5p expression and prospective molecular mechanisms in the metastasis of prostate cancer

The clinicopathological implication and prospective molecular mechanisms of miRNA-145-5p in the metastasis of prostate cancer (PCa) stand unclear. Herein, it is found that miRNA-145-5p expression was remarkably reduced in 131 cases of metastatic PCa than 1371 cases of localised ones, as the standardised mean differences (SMD) was -1.26 and the area under the curve (AUC) was 0.86, based on miRNA-chip and miRNA-sequencing datasets. The potential targets of miRNA-145-5p in metastatic PCa (n = 414) was achieved from the intersection of miRNA-145-5p transfected metastatic PCa cell line data, differential expression of metastatic PCa upregulated genes and online prediction databases. TOP2A was screened as one of the target hub genes by PPI network analysis, which was adversely related to miRNA-145-5p expression in both metastatic PCa (r = -0.504) and primary PCa (r = -0.281). Gene-chip and RNA-sequencing datasets, as well as IHC performed on clinical PCa samples, showed consistent upregulated expression of TOP2A mRNA and protein in PCa compared with non-PCa. The expression of TOP2A mRNA was also significantly higher in metastatic than localised PCa with the SMD being 1.72 and the AUC of sROC being 0.91. In summary, miRNA-145-5p may participate in PCa metastasis by binding TOP2A and be useful as a biomarker for the detection of metastatic PCa.

Identification of Key MicroRNAs and Mechanisms in Prostate Cancer Evolution Based on Biomarker Prioritization Model and Carcinogenic Survey

Background: Prostate cancer (PCa) is occurred with increasing incidence and heterogeneous pathogenesis. Although clinical strategies are accumulated for PCa prevention, there is still a lack of sensitive biomarkers for the holistic management in PCa occurrence and progression. Based on systems biology and artificial intelligence, translational informatics provides new perspectives for PCa biomarker prioritization and carcinogenic survey.

Methods: In this study, gene expression and miRNA-mRNA association data were integrated to construct conditional networks specific to PCa occurrence and progression, respectively. Based on network modeling, hub miRNAs with significantly strong single-line regulatory power were topologically identified and those shared by the condition-specific network systems were chosen as candidate biomarkers for computational validation and functional enrichment analysis.

Results: Nine miRNAs, i.e., hsa-miR-1-3p, hsa-miR-125b-5p, hsa-miR-145-5p, hsa-miR-182-5p, hsa-miR-198, hsa-miR-22-3p, hsa-miR-24-3p, hsa-miR-34a-5p, and hsa-miR-499a-5p, were prioritized as key players for PCa management. Most of these miRNAs achieved high AUC values (AUC > 0.70) in differentiating different prostate samples. Among them, seven of the miRNAs have been previously reported as PCa biomarkers, which indicated the performance of the proposed model. The remaining hsa-miR-22-3p and hsa-miR-499a-5p could serve as novel candidates for PCa predicting and monitoring. In particular, key miRNA-mRNA regulations were extracted for pathogenetic understanding. Here hsa-miR-145-5p was selected as the case and hsa-miR-145-5p/NDRG2/AR and hsa-miR-145-5p/KLF5/AR axis were found to be putative mechanisms during PCa evolution. In addition, Wnt signaling, prostate cancer, microRNAs in cancer etc. were significantly enriched by the identified miRNAs-mRNAs, demonstrating the functional role of the identified miRNAs in PCa genesis.

Conclusion: Biomarker miRNAs together with the associated miRNA-mRNA relations were computationally identified and analyzed for PCa management and carcinogenic deciphering. Further experimental and clinical validations using low-throughput techniques and human samples are expected for future translational studies.

Use of miR‑145 and testicular nuclear receptor 4 inhibition to reduce chemoresistance to docetaxel in prostate cancer

The human testicular nuclear receptor 4 (TR4) is a critical regulatory gene for the progression of prostate cancer (PCa). Although it has been revealed that TR4 causes chemoresistance in PCa via the activation of octamer-binding transcription factor 4 (OCT4), the detailed mechanism remains unexplored. In the present study, it was revealed that inhibition of TR4 by shRNA in PCa enhanced the sensitivity to docetaxel in vitro and in vivo. TR4 induced the downregulation of miR-145 by directly binding it to the promoter of miR-145, which was confirmed by chromatin immunoprecipitation analysis and luciferase assay. The overexpression of miR-145 suppressed both the chemoresistance and the expression of OCT4 mRNA and protein. Additionally, the TR4 shRNA mediated re-sensitization to docetaxel, along with the downregulated expression of OCT4, were reversed by the concurrent inhibition of miR-145. The luciferase assay revealed that the activity of the wild-type OCT4 3′ untranslated region reporter was suppressed. This suppression diminished when the miR-145 response element mutated. These findings suggest an undescribed regulatory pathway in PCa, by which TR4 directly suppressed the expression of miR-145, thereby inhibiting its direct target OCT4, leading to the promotion of chemoresistance in PCa.

Relationship between miR-143/145 cluster variations and cancer risk: proof from a Meta-analysis

Recent studies have suggested that single-nucleotide polymorphisms (SNPs) located in the miR-143/145 cluster might be linked to cancer risk. In this meta-analysis association study, we sought to quantitatively measure the strength of this association with cancer susceptibility in the overall analysis. Relevant publications were retrieved through a literature search in Web of Science, Medline, PubMed, Scopus, and Google scholar databases (updated January 22, 2020). Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were estimated under different genetic contrasted models. Our findings showed that rs4705341 (under allelic, codominant AA, dominant, and recessive), rs4705342 (under allelic, codominant TC, codominant CC, dominant, and recessive), and rs353292 (under allelic, codominant CT, and dominant) significantly decreased cancer risk. However, we did not find any association between the rs4705343, rs353293, rs3733845, and rs3733846 variants and cancer risk under any genetic models. The stratified analysis by cancer type showed that the rs41291957 and rs4705342 variants showed protective effects against colorectal- and prostate cancers, respectively. Our findings support the association between some miR-143/145 cluster variants and cancer risk. Replication large-scale studies on different races are encouraged to precisely delineate such associations.

MicroRNAs as Guardians of the Prostate: Those Who Stand before Cancer. What Do We Really Know about the Role of microRNAs in Prostate Biology?

Prostate cancer is the second leading cause of cancer-related deaths of men in the Western world. Despite recent advancement in genomics, transcriptomics and proteomics to understand prostate cancer biology and disease progression, castration resistant metastatic prostate cancer remains a major clinical challenge and often becomes incurable. MicroRNAs (miRNAs), about 22-nucleotide-long non-coding RNAs, are a group of regulatory molecules that mainly work through post-transcriptional gene silencing via translational repression. Expression analysis studies have revealed that miRNAs are aberrantly expressed in cancers and have been recognized as regulators of prostate cancer progression. In this critical review, we provide an analysis of reported miRNA functions and conflicting studies as they relate to expression levels of specific miRNAs and prostate cancer progression; oncogenic and/or tumor suppressor roles; androgen receptor signaling; epithelial plasticity; and the current status of diagnostic and therapeutic applications. This review focuses on select miRNAs, highly expressed in normal and cancer tissue, to emphasize the current obstacles faced in utilizing miRNA data for significant impacts on prostate cancer therapeutics.

Coordinated AR and microRNA regulation in prostate cancer

The androgen receptor (AR) remains a key driver of prostate cancer (PCa) progression, even in the advanced castrate-resistant stage, where testicular androgens are absent. It is therefore of critical importance to understand the molecular mechanisms governing its activity and regulation during prostate tumourigenesis. MicroRNAs (miRs) are small ∼22 nt non-coding RNAs that regulate target gene, often through association with 3′ untranslated regions (3′UTRs) of transcripts. They display dysregulation during cancer progression, can function as oncogenes or tumour suppressors, and are increasingly recognised as targets or regulators of hormonal action. Thus, understanding factors which modulate miRs synthesis is essential. There is increasing evidence for complex and dynamic bi-directional cross-talk between the multi-step miR biogenesis cascade and the AR signalling axis in PCa. This review summarises the wealth of mechanisms by which miRs are regulated by AR, and conversely, how miRs impact AR's transcriptional activity, including that of AR splice variants. In addition, we assess the implications of the convergence of these pathways on the clinical employment of miRs as PCa biomarkers and therapeutic targets.

Epigenetic regulation of prostate cancer: the theories and the clinical implications

Epigenetics is the main mechanism that controls transcription of specific genes with no changes in the underlying DNA sequences. Epigenetic alterations lead to abnormal gene expression patterns that contribute to carcinogenesis and persist throughout disease progression. Because of the reversible nature, epigenetic modifications emerge as promising anticancer drug targets. Several compounds have been developed to reverse the aberrant activities of enzymes involved in epigenetic regulation, and some of them show encouraging results in both preclinical and clinical studies. In this article, we comprehensively review the up-to-date roles of epigenetics in the development and progression of prostate cancer. We especially focus on three epigenetic mechanisms: DNA methylation, histone modifications, and noncoding RNAs. We elaborate on current models/theories that explain the necessity of these epigenetic programs in driving the malignant phenotypes of prostate cancer cells. In particular, we elucidate how certain epigenetic regulators crosstalk with critical biological pathways, such as androgen receptor (AR) signaling, and how the cooperation dynamically controls cancer-oriented transcriptional profiles. Restoration of a "normal" epigenetic landscape holds promise as a cure for prostate cancer, so we concluded by highlighting particular epigenetic modifications as diagnostic and prognostic biomarkers or new therapeutic targets for treatment of the disease.

A Gleason score-related outcome model for human prostate cancer: a comprehensive study based on weighted gene co-expression network analysis

BACKGROUND

Prostate cancer (PCa) is the second leading cause of cancer death in men in 2018. Thus, the evaluation of prognosis is crucial for clinical treatment decision of human PCa patients. We aim to establishing an effective and reliable model to predict the outcome of PCa patients.

METHODS

We first identified differentially expressed genes between prostate cancer and normal prostate in TCGA-PRAD and then performed WGCNA to initially identify the candidate Gleason score related genes. Then, the candidate genes were applied to construct a LASSO Cox regression analysis model. Numerous independent validation cohorts, time-dependent receiver operating characteristic (ROC), univariate cox regression analysis, nomogram were used to test the effectiveness, accuracy and clinical utility of the prognostic model. Furthermore, functional analysis and immune cells infiltration were performed.

RESULTS

Gleason score-related differentially expressed candidates were identified and used to build up the outcome model in TCGA-PRAD cohort and was validated in MSKCC cohort. We found the 3-gene outcome model (CDC45, ESPL1 and RAD54L) had good performance in predicting recurrence free survival, metastasis free survival and overall survival of PCa patients. Time-dependent ROC and nomogram indicated an ideal predictive accuracy and clinical utility of the outcome model. Moreover, outcome model was enriched in 28 pathways by GSVA and GSEA. In addition, the risk score was positively correlated with memory B cells, native CD4 T cells, activated CD4 memory T cells and eosinophil, and negatively correlated with plasma cells, resting CD4 memory T cells, resting mast cells and neutrophil.

CONCLUSIONS

In summary, our outcome model proves to be an effective prognostic model for predicting the risk of prognosis in PCa.

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.

The long noncoding RNA myocardial infarction-associated transcript modulates the epithelial-mesenchymal transition in renal interstitial fibrosis

AIMS

Renal interstitial fibrosis (RIF) is marked by the epithelial-mesenchymal transition (EMT) and excessive extracellular matrix deposition. The long noncoding RNA myocardial infarction-associated transcript (MIAT) facilitates RIF; however, the molecular mechanism of MIAT in RIF remains unclear. Here, we explored the possible underlying mechanisms through which MIAT modulates RIF.

MATERIALS AND METHODS

MIAT expression in human renal fibrotic tissues and unilateral ureteral obstruction (UUO) model mice was detected by qPCR. Transforming growth factor β1 (TGF-β1) was introduced to stimulate the EMT in human renal proximal tubular epithelial (HK-2) cells. CCK8, EdU, transwell and wound healing assays were employed to measure cell viability, proliferation, and migration respectively. RNA immunoprecipitation (RIP) assays and dual luciferase reporter assays were applied to determine the relationships among MIAT, miR-145, and EIF5A2.

KEY FINDINGS

MIAT was upregulated in human renal fibrotic tissues and UUO model mice compared with normal tissue adjacent to renal tumors and sham operation mice, respectively. MIAT knockdown reduced cell viability, proliferation, migration, and the EMT in HK-2 cells. Additionally, MIAT served as an endogenous sponge for miR-145 in the TGF-β1-induced-EMT in HK-2 cells, as demonstrated by dual luciferase reporter assays and RIP assays. EIF5A2 was confirmed as a target of miR-145, and MIAT knockdown suppressed EIF5A2 expression by sponging miR-145. Downregulation of EIF5A2 partly reversed induction of the EMT by miR-145 inhibitor transfection.

SIGNIFICANCE

MIAT promoted cell viability, proliferation, migration, and the EMT via regulation of the miR-145/EIF5A2 axis. These data established a potential therapy for RIF.

MicroRNA-145 Inhibits Cell Migration and Invasion in Colorectal Cancer by Targeting TWIST

Introduction

MicroRNAs function as oncogenes or tumor suppressors in the development of various human cancers. We investigated the effect of microRNA-145 (miR-145) on colorectal cancer (CRC) cell invasion and migration.

Methods

The levels of miR-145 in CRC cells were examined by quantitative PCR; Western blotting was used to detect TWIST1 (twist family bHLH transcription factor 1) protein and the epithelial–mesenchymal transition (EMT)-related proteins (E-cadherin, vimentin). Then, we transfected miR-145 mimics or inhibitor into CRC cells and used the wound healing and Transwell invasion assays to investigate their migration and invasive capability, respectively.

Results

The miR-145 mimics suppressed CRC cell invasion and migration significantly; in contrast, miR-145 downregulation had the opposite effect. Furthermore, miR-145 regulated TWIST1 levels negatively at transcriptional level. TWIST1 knockdown significantly inhibited the CRC cell migration ability and the number of CRC cells that crossed the Transwell membrane. There was no significant difference in terms of migration and invasive capability after the cells had been transfected with miR-145 mimics or inhibitor plus TWIST1 small interfering RNA (siRNA) as compared to the TWIST1 siRNA–only group. Furthermore, we demonstrate that the inhibition of miR-145 could enhance the capability for lung metastasis in vivo.

Conclusion

Taken together, these findings indicate that miR-145 acts as a new tumor suppressor by regulating TWIST1 and plays a vital role in the invasive and migration ability of CRC cells.

Circular RNAs are differentially expressed in prostate cancer and are potentially associated with resistance to enzalutamide

Most forms of castration-resistant prostate cancer (CRPC) are dependent on the androgen receptor (AR) for survival. While, enzalutamide provides a substantial survival benefit, it is not curative and many patients develop resistance to therapy. Although not yet fully understood, resistance can develop through a number of mechanisms, such as AR copy number gain, the generation of splice variants such as AR-V7 and mutations within the ligand binding domain (LBD) of the AR. circular RNAs (circRNAs) are a novel type of non-coding RNA, which can regulate the function of miRNA, and may play a key role in the development of drug resistance. circRNAs are highly resistant to degradation, are detectable in plasma and, therefore may serve a role as clinical biomarkers. In this study, AR-V7 expression was assessed in an isogenic model of enzalutamide resistance. The model consisted of age matched control cells and two sub-line clones displaying varied resistance to enzalutamide. circRNA profiling was performed on the panel using a high throughout microarray assay. Bioinformatic analysis identified a number of differentially expressed circRNAs and predicted five miRNA binding sites for each circRNA. miRNAs were stratified based on known associations with prostate cancer, and targets were validated using qPCR. Overall, circRNAs were more often down regulated in resistant cell lines compared with control (588 vs. 278). Of particular interest was hsa_circ_0004870, which was down-regulated in enzalutamide resistant cells (p ≤ 0.05, vs. sensitive cells), decreased in cells that highly express AR (p ≤ 0.01, vs. AR negative), and decreased in malignant cells (p ≤ 0.01, vs. benign). The associated parental gene was identified as RBM39, a member of the U2AF65 family of proteins. Both genes were down-regulated in resistant cells (p < 0.05, vs. sensitive cells). This is one of the first studies to profile and demonstrate discrete circRNA expression patterns in an enzalutamide resistant cell line model of prostate cancer. Our data suggests that hsa_circ_0004870, through RBM39, may play a critical role in the development of enzalutamide resistance in CRPC.

The role of miRNAs as biomarkers in prostate cancer

There is an urged need of non-invasive biomarkers for the implementation of precision medicine. These biomarkers are required to these days for improving prostate cancer (PCa) screening, treatment or stratification in current clinical strategies. There are several commercial kits (Oncotype DX genomic prostate score^®, Prolaris^®, among others) that use genomic changes, rearrangement or even non-coding RNA events. However, none of them are currently used in the routine clinical practice. Many recent studies indicate that miRNAs are relevant molecules (small single-stranded non-coding RNAs that regulate gene expression of more than 30% of human genes) to be implement non-invasive biomarkers. However, contrasting to others tumors, such as breast cancer where miR-21 seems to be consistently upregulated; PCa data are controversial. Here we reported an extended revision about the role of miRNAs in PCa including data of AR signaling, cell cycle, EMT process, CSCs regulation and even the role of miRNAs as PCa diagnostic, prognostic and predictive tool. It is known that current biomedical research uses big-data analysis like Next Generation Sequencing (NGS) analysis. We also conducted an extensive online search, including the main platforms and kits for miRNAs massive analysis (like MiSeq, Nextseq 550, or Ion S5™ systems) indicating their pros, cons and including pre-analytical and analytical issues of miRNA studies.

Interplay between the androgen receptor signaling axis and microRNAs in prostate cancer

The androgen receptor (AR) is a ligand-activated transcription factor that drives prostate cancer. Since therapies that target the AR are the mainstay treatment for men with metastatic disease, it is essential to understand the molecular mechanisms underlying oncogenic AR signaling in the prostate. miRNAs are small, non-coding regulators of gene expression that play a key role in prostate cancer and are increasingly recognized as targets or modulators of the AR signaling axis. In this review, we examine the regulation of AR signaling by miRNAs and vice versa and discuss how this interplay influences prostate cancer growth, metastasis and resistance to therapy. Finally, we explore the potential clinical applications of miRNAs implicated in the regulation of AR signaling in this prevalent hormone-driven disease.

MicroRNA 141 is associated to outcome and aggressive tumor characteristics in prostate cancer

A large number of miRNAs influence key cellular processes involved in prostate tumorigenesis. Previous studies have demonstrated high expression of miRNAs in human prostate cancer (PC) tissues and cell lines. In previous microarray data, we found miR-141 to be upregulated and miR-145 to be downregulated in PC. In this large PC cohort (n = 535), we explored the prognostic role of miR-141 and miR-145 in PC. Tumor epithelial (TE) and tumor stromal (TS) areas were evaluated separately and combined (TE + TS). In situ hybridization was used to evaluate the expression of the miRNAs. We found that miR-141 (TE) correlated significantly to Gleason score ≥8 (p = 0.040) and large tumor size (≥20 mm, p = 0.025) and miR-141 (TE + TS) to Gleason grade (p = 0.001). MiR-145 correlated to pT-stage (p = 0.038), tumor size (p = 0.025), Gleason grade (p = 0.051) and PSA (p = 0.032). In univariate analysis miR-141 (TE + TS) was significantly associated with biochemical failure-free survival (BFFS, p = 0.007) and clinical failure-free survival (CFFS, p = 0.021). For miR-145, there were no differences between patients with high versus low expression. In multivariate analysis overexpression of miR-141 in tumor epithelium and tumor stroma was significantly associated with BFFS (HR = 1.07 CI95% 1.00–1.14, p = 0.007). To conclude, high expression of miR-141 appears associated with increased risk of biochemical PC recurrence.

MicroRNA-145 performs as a tumor suppressor in human esophageal squamous cell carcinoma by targeting phospholipase C epsilon 1

Esophageal squamous cell carcinoma (ESCC) is the leading pathologic type in China. miR-145 has been reported to be downregulated in multiple tumors. This study was aimed to investigate the role of miR-145 in ESCC. miR-145 expression was investigated in 65 ESCC samples as well as four ESCC cell lines by quantitative real-time polymerase chain reaction (qRT-PCR). Targetscan 6.2 website (http://www.targetscan.org/) was used to predict the targets of miR-145. Expression of phospholipase C epsilon 1 (PLCE1) messenger RNA and protein was detected by qRT-PCR or Western blot. MTT and wound healing assay were conducted to explore the effects of miR-145 on the proliferation and migration of ESCC cell lines, respectively. miR-145 was significantly decreased in ESCC tissues. An inverse correlation between miR-145 and invasion depth and TNM stage were observed. PLCE1 was a direct target of miR-145, and the expression of PLCE1 was inversely correlated with miR-145 expression in ESCC tissues. In addition, overexpression of miR-145 suppressed cell proliferation and migration in ESCC cells. The enforced expression of PLCE1 partially reversed the suppressive effect of miR-145. These results prove that miR-145 may perform as a tumor suppressor in ESCC by targeting PLCE1.

The Prognostic Value and Regulatory Mechanisms of microRNA-145 in Various Tumors: A Systematic Review and Meta-analysis of 50 Studies

Acting as an important tumor-related miRNA, the clinical significance and underlying mechanisms of miR-145 in various malignant tumors have been investigated by numerous studies. This study aimed to comprehensively estimate the prognostic value and systematically illustrate the regulatory mechanisms of miR-145 based on all eligible literature.Relevant studies were acquired from multiple online databases. Overall survival (OS) and progression-free survival (PFS) were used as primary endpoints. Detailed subgroup analyses were performed to decrease the heterogeneity among studies and recognize the prognostic value of miR-145. All statistical analyses were performed with RevMan software version 5.3 and STATA software version 14.1. A total of 48 articles containing 50 studies were included in the meta-analysis. For OS, the pooled results showed that low miR-145 expression in tumor tissues was significantly associated with worse OS in patients with various tumors [HR = 1.70; 95% confidence interval (CI), 1.46-1.99; P < 0.001). Subgroup analysis based on tumor type showed that the downregulation of miR-145 was associated with unfavorable OS in colorectal cancer (HR = 2.17; 95% CI, 1.52-3.08; P < 0.001), ovarian cancer (HR = 2.15; 95% CI, 1.29-3.59; P = 0.003), gastric cancer (HR = 1.78; 95% CI, 1.35-2.36; P < 0.001), glioma (HR = 1.65; 95% CI, 1.30-2.10; P < 0.001), and osteosarcoma (HR = 2.28; 95% CI, 1.50-3.47; P < 0.001). For PFS, the pooled results also showed that the downregulation of miR-145 was significantly associated with poor PFS in patients with multiple tumors (HR = 1.39; 95% CI, 1.16-1.67; P < 0.001), and the subgroup analyses further identified that the low miR-145 expression was associated with worse PFS in patients with lung cancer (HR = 1.97; 95% CI, 1.25-3.09; P = 0.003) and those of Asian descent (HR = 1.50; 95% CI, 1.23-1.82; P < 0.001). For the regulatory mechanisms, we observed that numerous tumor-related transcripts could be targeted by miR-145-5p or miR-145-3p, as well as the expression and function of miR-145-5p could be regulated by multiple molecules.This meta-analysis indicated that downregulated miR-145 in tumor tissues or peripheral blood predicted unfavorable prognostic outcomes for patients suffering from various malignant tumors. In addition, miR-145 was involved in multiple tumor-related pathways and the functioning of significant biological effects. miR-145 is a well-demonstrated tumor suppressor, and its expression level is significantly correlated with the prognosis of patients with multiple malignant tumors.

Therapeutic microRNAs in human cancer

MicroRNAs (miRNAs) are RNA molecules at about 22 nucleotide in length that are non-coding, which regulate gene expression in the post-transcriptional level by performing degradation or blocks translation of the target mRNA. It is known that they play roles in mechanisms such as metabolic regulation, embryogenesis, organogenesis, differentiation and growth control by providing post-transcriptional regulation of gene expression. With these properties, miRNAs play important roles in the regulation of biological processes such as proliferation, differentiation, apoptosis, drug resistance mechanisms in eukaryotic cells. In addition, there are miRNAs that can be used for cancer therapy. Tumor cells and tumor microenvironment have different miRNA expression profiles. Some miRNAs are known to play a role in the onset and progression of the tumor. miRNAs with oncogenic or tumor suppressive activity specific to different cancer types are still being investigated. This review summarizes the role of miRNAs in tumorigenesis, therapeutic strategies in human cancer and current studies.

Promoter Methylation-Regulated miR-145-5p Inhibits Laryngeal Squamous Cell Carcinoma Progression by Targeting FSCN1

Laryngeal squamous cell carcinoma (LSCC) is a common form of head and neck cancer with poor prognosis. However, the mechanism underlying the pathogenesis of LSCC remains unclear. Here, we demonstrated increased expression of fascin actin-bundling protein 1 (FSCN1) and decreased expression of microRNA-145-5p (miR-145-5p) in a clinical cohort of LSCC. Luciferase assay revealed that miR-145-5p is a negative regulator of FSCN1. Importantly, low miR-145-5p expression was correlated with TNM (tumor, node, metastasis) status and metastasis. Moreover, cases with low miR-145-5p/high FSCN1 expression showed poor prognosis, and these characteristics together served as independent prognostic indicators of survival. Gain- and loss-of-function studies showed that miR-145-5p overexpression or FSCN1 knockdown inhibited LSCC migration, invasion, and growth by suppressing the epithelial-mesenchymal transition along with inducing cell-cycle arrest and apoptosis. Additionally, hypermethylation of the miR-145-5p promoter suggested that repression of miR-145-5p arises through epigenetic inactivation. LSCC tumor growth in vivo could be inhibited by using miR-145-5p agomir or FSCN1 small interfering RNA (siRNA), which highlights the potential for clinical translation. Collectively, our findings indicate that miR-145-5p plays critical roles in inhibiting the progression of LSCC by suppressing FSCN1. Both miR-145-5p and FSCN1 are important potential prognostic markers and therapeutic targets for LSCC.

HDAC-Linked "Proliferative" miRNA Expression Pattern in Pancreatic Neuroendocrine Tumors

Epigenetic factors are essentially involved in carcinogenesis, tumor promotion, and chemoresistance. Two epigenetic key players are miRNAs and histone deacetylases (HDACs). As previously shown by own theoretical databank analysis, the crosstalk between miRNAs and HDACs is relevant in different human chronic diseases and cancerogenic pathways. We aimed to investigate a potential connection between the expression of a well-defined subset of "proliferation-associated" miRNAs and the expression of HDACs as well as clinical parameters in pancreatic neuroendocrine tumors (pNETs).

MATERIALS AND METHODS

Expression levels of miRNA132-3p, miRNA145-5p, miRNA183-5p, miRNA34a-5p, and miRNA449a in 57 pNETs resected between 1997 and 2015 were measured and linked to the immunohistochemical expression pattern of members of the four HDAC classes on human tissue microarrays. All pNET cases were clinically and pathologically characterized according to published guidelines. Correlation analysis revealed a significant association between expression of specific miRNAs and two members of the HDAC family (HDAC3 and HDAC4). Additionally, a linkage between miRNA expression and clinico-pathological parameters like grading, TNM-staging, and hormone activity was found. Moreover, overall and disease-free survival is statistically correlated with the expression of the investigated miRNAs. Overall, we demonstrated that specific miRNAs could be linked to HDAC expression in pNETs. Especially miRNA449a (associated with HDAC3/4) seems to play an important role in pNET proliferation and could be a potential prognostic factor for poor survival. These first data could help, to improve our knowledge of the complex interactions of the epigenetic drivers in pNETs for further therapeutic approaches.

Increased MALAT1 expression contributes to cisplatin resistance in non-small cell lung cancer

Cisplatin-based chemotherapy is commonly used for the clinical treatment of patients with non-small cell lung cancer (NSCLC). However, the anti-tumor efficacy of cisplatin is limited by poor clinical response and the development of chemoresistance. At present, the underlying mechanism for cisplatin resistance remains unclear. In the present study, it was identified that metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a long non-coding RNA that has been demonstrated to function as an oncogene, was increased in tumor tissues from patients with cisplatin-resistant NSCLC. In addition, the MALAT1 level was increased in A549rCDDP cells compared with the parental A549 cells. Silencing of MALAT1 sensitized A549rCDDP cells to cisplatin treatment, while overexpression of MALAT1 in A549 cells decreased their sensitivity towards cisplatin. Through analysis of the gene expression in patient samples, a decrease in miR-145 and an increase in Kruppel-like factor 4 (KLF4) in tumor tissues compared with adjacent normal tissues was observed. A negative association between MALAT1 and miR-145 was also identified in A549 cells and A549rCDDP cells. Furthermore, reverse transcription quantitative polymerase chain reaction and western blotting identified that KLF4 was positively and negatively regulated by MALAT1 and miR-145, respectively. The direct regulatory association between MALAT1 and miR-145 and the target gene KLF4 was additionally confirmed using a luciferase reporter assay. Knockdown of MALAT1 reversed cisplatin resistance in A549rCDDP cells. Taken together, these data indicated that MALAT1 decreased the sensitivity of NSCLC to cisplatin via the regulation of miR-145 and KLF4.

Nanoparticle-based targeted cancer strategies for non-invasive prostate cancer intervention

Prostate cancer is screened by testing circulating levels of the prostate-specific antigen (PSA) biomarker, monitoring changes over time, or a digital rectal exam. Abnormal results often lead to prostate biopsy. Prostate cancer positive patients are stratified into very low-risk, low-risk, intermediate-risk, and high-risk, based on clinical classification parameters, to assess therapy options. However, there remains a gap in our knowledge and a compelling need for improved risk stratification to inform clinical decisions and reduce both over-diagnosis and over-treatment. Further, current strategies for clinical intervention do not distinguish clinically aggressive prostate cancer from indolent disease. This mini-review takes advantage of a large number of functionally characterized microRNAs (miRNA), epigenetic regulators of prostate cancer, that define prostate cancer cell activity, tumor stage, and circulate as biomarkers to monitor disease progression. Nanoparticles provide an effective platform for targeted delivery of miRNA inhibitors or mimics specifically to prostate tumor cells to inhibit cancer progression. Several prostate-specific transmembrane proteins expressed at elevated levels in prostate tumors are under investigation for targeting therapeutic agents to prostate cancer cells. Given that prostate cancer progresses slowly, circulating miRNAs can be monitored to identify tumor progression in indolent disease, allowing identification of miRNAs for nanoparticle intervention before the crucial point of transition to aggressive disease. Here, we describe clinically significant and non-invasive intervention nanoparticle strategies being used in clinical trials for drug and nucleic acid delivery. The advantages of mesoporous silica-based nanoparticles and a number of candidate miRNAs for inhibition of prostate cancer are discussed.

Expression and function of the miR-143/145 cluster in vitro and in vivo in human breast cancer

MicroRNAs (miRNAs) are small non-coding RNAs that function as post-transcriptional regulators of gene expression and are dysregulated in cancer. Studies of miRNAs to explore their potential as diagnostic and prognostic markers are of great scientific interest. Here, we investigate the functional properties and expression of the miR-143/145 cluster in breast cancer (BC) in vitro and in vivo. The ER positive MCF7, the HER2 positive SK-BR-3, and the triple negative cell line MDA-MB-231 were used to assess cell proliferation and cell invasion. Expression of miRNA in 108 breast cancers in the Norwegian Women and Cancer Study and 44 benign tissue controls were analyzed by microarray and validated by RT-PCR. Further, in situ hybridization (ISH) was used to study the cellular and subcellular distribution of the miRNAs. In vitro, miR-143 promoted proliferation of MCF7 and MDA-MB-231 cells, whereas miR-145 and the cotransfection of both miRNAs inhibited proliferation in all three cell lines. The cells’ invasive capacity was reduced after transfection and cotransfection of the miRNAs. In line with the tumor suppressive functions in vitro, the expression of miR-143 and miR-145 was lower in malignant compared to benign breast tissue, and lower in the more aggressive tumors with higher tumor grade, loss of ER and the basal-like phenotype. ISH revealed miR-143 to be cytoplasmatic and predominantly expressed in luminal cells in benign tissue, whilst miR-145 was nuclear and with strong staining in myoepithelial cells. Both miRNAs were present in malignant epithelial cells and stromal fibroblasts in BC. This study demonstrates that miR-143 and -145 have functional properties and expression patterns typical for tumor suppressors, but the function is influenced by cellular factors such as cell type and miRNA cotransfection. Further, the nuclear functions of miR-145 should be explored for a more complete understanding of the complexity of miRNA regulation and function in BC.

DNA Methylation and Urological Cancer, a Step Towards Personalized Medicine: Current and Future Prospects

Urologic malignancies are some of the commonest tumors often curable when diagnosed at early stage. However, accurate diagnostic markers and faithful predictors of prognosis are needed to avoid over-diagnosis leading to overtreatment. Many promising exploratory studies have identified epigenetic markers in urinary malignancies based on DNA methylation, histone modification and non-coding ribonucleic acid (ncRNA) expression that epigenetically regulate gene expression. We review and discuss the current state of development and the future potential of epigenetic biomarkers for more accurate and less invasive detection of urological cancer, tumor recurrence and progression of disease serving to establish diagnosis and monitor treatment efficacies. The specific clinical implications of such methylation tests on therapeutic decisions and patient outcome and current limitations are also discussed.

Impact of novel miR-145-3p regulatory networks on survival in patients with castration-resistant prostate cancer

BACKGROUND

Despite recent advancements, metastatic castration-resistant prostate cancer (CRPC) is not considered curative. Novel approaches for identification of therapeutic targets of CRPC are needed.

METHODS

Next-generation sequencing revealed 945-1248 miRNAs from each lethal mCRPC sample. We constructed miRNA expression signatures of CRPC by comparing the expression of miRNAs between CRPC and normal prostate tissue or hormone-sensitive prostate cancer (HSPC). Genome-wide gene expression studies and in silico analyses were carried out to predict miRNA regulation and investigate the functional significance and clinical utility of the novel oncogenic pathways regulated by these miRNAs in prostate cancer (PCa).

RESULTS

Based on the novel miRNA expression signature of CRPC, miR-145-5p and miR-145-3p were downregulated in CRPC. By focusing on miR-145-3p, which is a passenger strand and has not been well studied in previous reports, we showed that miR-145-3p targeted 4 key molecules, i.e., MELK, NCAPG, BUB1, and CDK1, in CPRC. These 4 genes significantly predicted survival in patients with PCa.

CONCLUSIONS

Small RNA sequencing for lethal CRPC and in silico analyses provided novel therapeutic targets for CRPC.

Targeting MicroRNAs in Prostate Cancer Radiotherapy

Radiotherapy is one of the most important treatment options for localized early-stage or advanced-stage prostate cancer (CaP). Radioresistance (relapse after radiotherapy) is a major challenge for the current radiotherapy. There is great interest in investigating mechanisms of radioresistance and developing novel treatment strategies to overcome radioresistance. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression at the post-transcriptional level, participating in numerous physiological and pathological processes including cancer invasion, progression, metastasis and therapeutic resistance. Emerging evidence indicates that miRNAs play a critical role in the modulation of key cellular pathways that mediate response to radiation, influencing the radiosensitivity of the cancer cells through interplaying with other biological processes such as cell cycle checkpoints, apoptosis, autophagy, epithelial-mesenchymal transition and cancer stem cells. Here, we summarize several important miRNAs in CaP radiation response and then discuss the regulation of the major signalling pathways and biological processes by miRNAs in CaP radiotherapy. Finally, we emphasize on microRNAs as potential predictive biomarkers and/or therapeutic targets to improve CaP radiosensitivity.

Exploiting Epigenetic Alterations in Prostate Cancer

Prostate cancer affects an increasing number of men worldwide and is a leading cause of cancer-associated deaths. Beside genetic mutations, many epigenetic alterations including DNA and histone modifications have been identified in clinical prostate tumor samples. They have been linked to aberrant activity of enzymes and reader proteins involved in these epigenetic processes, leading to the search for dedicated inhibitory compounds. In the wake of encouraging anti-tumor efficacy results in preclinical models, epigenetic modulators addressing different targets are now being tested in prostate cancer patients. In addition, the assessment of microRNAs as stratification biomarkers, and early clinical trials evaluating suppressor microRNAs as potential prostate cancer treatment are being discussed.

Curcumin sensitizes prostate cancer cells to radiation partly via epigenetic activation of miR-143 and miR-143 mediated autophagy inhibition

Curcumin has been reported as a radiosensitizer in prostate cancer. But the underlying mechanism is not well understood. In this study, we firstly assessed how curcumin affects the expression of miR-143/miR-145 cluster. Then, we investigated whether miR-143 is involved in regulation of radiosensitivity and its association with autophagy in prostate cancer cells. Our data showed that PC3, DU145 and LNCaP cells treated with curcumin had significantly restored miR-143 and miR-145 expression. Curcumin showed similar effect as 5-AZA-dC on reducing methylation of CpG dinucleotides in miR-143 promoter. In addition, curcumin treatment reduced the expression of DNMT1 and DNMT3B, which contribute to promoter hypermethylation of the miR-143/miR-145 cluster. Therefore, we infer that curcumin can restore miR-143 and miR-145 expression via hypomethylation. MiR-143 overexpression and curcumin pretreatment enhanced radiation induced cancer cell growth inhibition and apoptosis. MiR-143 and curcumin remarkably reduced radiation-induced autophagy in PC3 and DU145 cells. MiR-143 overexpression alone also reduced the basal level of autophagy in DU145 cells. Mechanistically, miR-143 can suppress autophagy in prostate cancer cells at least via downregulating ATG2B. Based on these findings, we infer that curcumin sensitizes prostate cancer cells to radiation partly via epigenetic activation of miR-143 and miR-143 mediated autophagy inhibition.

miR-143 Induces the Apoptosis of Prostate Cancer LNCap Cells by Suppressing Bcl-2 Expression

Background

Prostate cancer has become a serious threat to the life of patients. microRNAs are small non-coding RNA molecules that regulate the growth and apoptosis of cells. We aimed to investigate the regulation and mechanism of microRNA (miR-143) in the proliferation and apoptosis of prostate cancer LNCap cells.

Material/Methods

miR-143 and control scramble miRNA were synthesized and respectively transfected into LNCap cells. The proliferation and apoptosis were detected by MTT assay, flow cytometry, and caspase-3 activity assay. The intracellular expression of Bcl-2 was determined by Western blot. Further, LNCap cells were transfected with small interfering RNA (siRNA) targeting Bcl-2 (siBcl-2) or plasmid expressing Bcl-2, followed by transfection of miR-143 or control miRNA. Bcl-2 expression was detected by Western blot, and cell apoptosis was measured by caspase-3 activity assay.

Results

Transfection of miR-143 significantly inhibited the proliferation of LNCap cells (P=0.0073), increased the percentage of externalized phosphatidylserine (P=0.0042), activated the caspase-3 (P=0.0012), and decreased the expression of Bcl-2 (P=0.012) when compared with the control miRNA group. The expression of Bcl-2 was significantly reduced after siBcl-2 transfection. The apoptosis in the siBcl-2+miR-143 group was significantly increased compared with that in the miR-143 group (P=0.036), whereas there was no significant difference in the apoptosis between the siBcl-2+miRNA and miRNA groups. The expression of Bcl-2 was obviously higher after the transfection of Bcl-2-expressing plasmid. The apoptosis in Bcl-2+miR-143 group was significantly reduced compared with the miR-143 group (P=0.031), whereas no significant difference in the apoptosis was detected between the miRNA and Bcl-2+miRNA groups.

Conclusions

Transfection of miR-143 induces the apoptosis of prostate cancer LNCap cells by down-regulating Bcl-2 expression, suggesting that Bcl-2 might be a potential therapeutic target for prostate cancer.

Deciphering the function of non-coding RNAs in prostate cancer

The advent of next-generation sequencing methods is fuelling the discovery of multiple non-coding RNA transcripts with direct implication in cell biology and homeostasis. This new layer of biological regulation seems to be of particular importance in human pathogenesis, including cancer. The aberrant expression of ncRNAs is a feature of prostate cancer, as they promote tumor-suppressive or oncogenic activities, controlling multicellular events leading to carcinogenesis and tumor progression. From the small RNAs involved in the RNAi pathway to the long non-coding RNAs controlling chromatin remodeling, alternative splicing, and DNA repair, the non-coding transcriptome represents the significant majority of transcriptional output. As such, ncRNAs appear as exciting new diagnostic, prognostic, and therapeutic tools. However, additional work is required to characterize the RNA species, their functions, and their applicability to clinical practice in oncology. In this review, we summarize the most important features of ncRNA biology, emphasizing its relevance in prostate carcinogenesis and its potential for clinical applications.