Clinical significance of miRNA host gene promoter methylation in prostate cancer

Blocking the MIR155HG/miR-155 axis reduces CTGF-induced inflammatory cytokine production and α-SMA expression via upregulating AZGP1 in hypertrophic scar fibroblasts

Hypertrophic scarring (HS) is a pathological condition characterized by excessive fibrosis and inflammation, resulting in excessive extracellular matrix formation in the skin. MIR155HG, a long non-coding RNA, is abnormally upregulated in fibrotic tissues; however, its underlying mechanism is poorly understood. Using single-cell sequencing data, we analyzed connective tissue growth factor (CTGF) expression in various cell types in HS and normal skin tissues and MIR155HG expression in clinical samples. To investigate the mechanism of fibrosis, an in vitro model using CTGF-treated hypertrophic scar fibroblasts (HSFBs) was established and qRT-PCR, western blotting and ELISA assays were performed to investigate the expression of interleukin (IL)-1β, IL-6, and mesenchymal markers α-smooth muscle actin (α-SMA). CTGF stimulates MIR155HG level through phosphorylated STAT3 binding to the MIR155HG promoter. We analyzed the methylation of MIR155HG, assessed the levels of miR-155-5p/-3p in CTGF-treated HSFBs and identified differentially expressed genes among HS and NS samples using the Gene Expression Omnibus RNA sequencing data. The binding between miR-155-5p/-3p and AZGP1 was confirmed using a dual-luciferase assay and inflammatory cytokine production and α-SMA expression were investigated in rescue experiments. The findings revealed that CTGF elevated inflammatory cytokine production, α-SMA and MIR155HG expression in HSFBs. MIR155HG is upregulated in HS tissues due to low DNA methylation. Mechanistically, miR-155-5p/-3p was directly bound to MIR155HG 3'UTR. MIR155HG silencing inhibited cytokine production and α-SMA expression by repressing the generation of miR-155-5p/-3p in CTGF-treated HSFBs. Bioinformatics analysis and luciferase reporter assays revealed that miR-155-5p/-3p targets AZGP1. In addition, transfection with plasmids carrying AZGP1 cDNA significantly inhibited the signaling activity of miR-155-5p/-3 p-overexpressing HSFBs. Our findings highlight the importance of the MIR155HG/miR-155/AZGP1 axis in regulating cytokine production and α-SMA in HS.

miR-26a-5p restoration via EZH2 silencing blocks the IL-6/STAT3 axis to repress the growth of prostate cancer

BACKGROUND

Interleukin-6 (IL-6) is involved in the activation of several oncogenic pathways in prostate cancer. However, its upstream trans-signaling pathway remains largely unknown. This work proposes a mechanistic explanation of IL-6's upstream effectors in prostate carcinogenesis.

RESEARCH DESIGN & METHODS

Samples were harvested to validate the expression of EZH2, miR-26a-5p, and IL-6. Moreover, the protein and its phosphorylation of STAT3 (signal transducer and transcription activator 3) were assessed in prostate cancer cells. We explored the effects of these effectors on malignant phenotypes in vitro and tumor growth in vivo using functional assays. Bioinformatics analysis, dual-luciferase reporter gene assays, and chromatin immunoprecipitation (ChIP) assays were used to determine their binding relationships.

RESULTS

Overexpression of EZH2 and IL-6, and under expression of miR-26a-5p was observed in prostate cancer. Silencing IL-6 repressed STAT3 to suppress the malignant phenotypes of prostate cancer cells. Mechanistically, EZH2 inhibited miR-26a-5p expression by promoting H3K27 histone methylation, and miR-26a-5p restricted the malignant phenotypes of prostate cancer by targeting IL-6. Ectopic EZH2 expression reduced xenograft growth by inhibiting miR-26a-5p and activating the IL-6/STAT3 axis.

CONCLUSION

EZH2 May potentially be involved in regulating its expression by recruiting H3K27me3 to the miR-26a-5p promoter region, which could further impact the IL6/STAT3 pathway.

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.

MiR-124-3p inhibits tumor progression in prostate cancer by targeting EZH2

Prostate cancer (PCa) is widespread cancer with significant morbidity and mortality rates. MicroRNAs (miRNAs) have been identified as important post-transcriptional modulators in various malignancies. This study investigated the miR-124-3p effect on PCa cell proliferation, infiltration, and apoptosis. EZH2 and miR-124-3p expression levels were measured in PCa tissues. PCa cell lines DU145 and PC3 were transfected with miR-124-3p inhibitors or analogs. EZH2 and miR-124-3p linkage was validated by conducting the luciferase enzyme reporter test. The cell viability and apoptosis were assessed by flow cytometry and MTT test. Cell movement was noted during infiltration using transwell assays. EZH2, AKT, and mTOR contents were assessed using qRT-PCR and western blotting. In clinical PCa specimens, miR-124-3p and EZH2 contents were inversely correlated. Further research has demonstrated that EZH2 is the miR-124-3p direct target. Furthermore, miR-124-3p overexpression reduced EZH2 levels and lowered cell viability, infiltration, and promoted cell death, whereas miR-124-3p silencing had the opposite effect. Overexpression of miR-124-3p decreased the phosphorylation level of AKT and mTOR, whereas miR-124-3p downregulation produced the opposite result. Our findings depict that miR-124-3p prevents PCa proliferative and invasive processes while promoting apoptosis by targeting EZH2.

Protective effect of hepatocyte-enriched lncRNA-Mir122hg by promoting hepatocyte proliferation in acute liver injury

Some long noncoding RNAs (lncRNAs), which harbor microRNAs in their gene sequence and are also known as microRNA host gene derived lncRNAs (lnc-MIRHGs), play a dominant role alongside miRNAs, or both perform biological functions synergistically or independently. However, only a small number of lnc-MIRHGs have been identified. Here, multiple liver injury datasets were analyzed to screen and identify the target lncRNA Mir122hg. Mir122hg was mainly enriched in liver tissues with human-mouse homology. In both CCl₄-induced acute liver injury and Dgal/LPS-induced fulminant liver failure in mice, Mir122hg was sharply downregulated at the early stage, while a subsequent significant increase was only found in the CCl₄ group with liver recovery. Overexpression and silencing assays confirmed that Mir122hg played a protective role in acute injury by promoting hepatocyte proliferation in vivo and in vitro. Consistent with the results of gene enrichment analysis, Mir122hg binding to C/EBPα affected its transcriptional repression, promoted gene transcription of downstream chemokines, Cxcl2, Cxcl3, and Cxcl5, and exerted pro-proliferative effects on hepatocytes through activation of the AKT/GSK-3β/p27 signaling pathway by CXC/CXCR2 complexes. This study identifies a novel lncRNA with protective effects in acute liver injury and demonstrates that the binding of Mir122hg-C/EBPα promotes hepatocyte proliferation via upregulation of CXC chemokine and activation of AKT signaling.

The Potential of MicroRNAs as Non-Invasive Prostate Cancer Biomarkers: A Systematic Literature Review Based on a Machine Learning Approach

Simple Summary

Prostate cancer (PCa) is the most common cancer in men worldwide. Screening and diagnosis are based on prostate-specific antigen (PSA) blood testing and digital rectal examination. Nevertheless, these methods are not specific and have a high risk of mistaken results. This has led to overtreatment and unnecessary radical therapy; thus, better prognostic tools are urgently needed. In this view, microRNAs (miRs) appear as potential non-invasive biomarkers for PCa diagnosis, prognosis, and therapy. As the scientific literature available in this field is huge and very often controversial, we identified and discussed three topics that characterize the investigated research area by combining the big data from the literature together with a novel machine learning approach. By analyzing the papers clustered into these topics we have offered a deeper understanding of the current research, which helps to contribute to the advancement of this research field.

Abstract

Background: Prostate cancer (PCa) is the second leading cause of cancer-related deaths in men. Although the prostate-specific antigen (PSA) test is used in clinical practice for screening and/or early detection of PCa, it is not specific, thus resulting in high false-positive rates. MicroRNAs (miRs) provide an opportunity as biomarkers for diagnosis, prognosis, and recurrence of PCa. Because the size of the literature on it is increasing and often controversial, this study aims to consolidate the state-of-art of relevant published research. Methods: A Systematic Literature Review (SLR) approach was applied to analyze a set of 213 scientific publications through a text mining method that makes use of the Latent Dirichlet Allocation (LDA) algorithm. Results and Conclusions: The result of this activity, performed through the MySLR digital platform, allowed us to identify a set of three relevant topics characterizing the investigated research area. We analyzed and discussed all the papers clustered into them. We highlighted that several miRs are associated with PCa progression, and that their detection in patients’ urine seems to be the more reliable and promising non-invasive tool for PCa diagnosis. Finally, we proposed some future research directions to help future scientists advance the field further.

Identification of key miRNAs in prostate cancer progression based on miRNA-mRNA network construction

Prostate cancer (PC) is one of the major male cancers. Differential diagnosis of PC is indispensable for the individual therapy, i.e., Gleason score (GS) that describes the grade of cancer can be used to choose the appropriate therapy. However, the current techniques for PC diagnosis and prognosis are not always effective. To identify potential markers that could be used for differential diagnosis of PC, we analyzed miRNA-mRNA interactions and we build specific networks for PC onset and progression. Key differentially expressed miRNAs for each GS were selected by calculating three parameters of network topology measures: the number of their single regulated mRNAs (NSR), the number of target genes (NTG) and NSR/NTG. miRNAs that obtained a high statistically significant value of these three parameters were chosen as potential biomarkers for computational validation and pathway analysis. 20 miRNAs were identified as key candidates for PC. 8 out of 20 miRNAs (miR-25-3p, miR-93-3p, miR-122-5p, miR-183-5p, miR-615-3p, miR-7-5p, miR-375, and miR-92a-3p) were differentially expressed in all GS and proposed as biomarkers for PC onset. In addition, "Extracellular-receptor interaction", "Focal adhesion", and "microRNAs in cancer" were significantly enriched by the differentially expressed target genes of the identified miRNAs. miR-10a-5p was found to be differentially expressed in GS 6, 7, and 8 in PC samples. 3 miRNAs were identified as PC GS-specific differentially expressed miRNAs: miR-155-5p was identified in PC samples with GS 6, and miR-142-3p and miR-296-3p in PC samples with GS 9. The efficacy of 20 miRNAs as potential biomarkers was revealed with a Random Forest classification using an independent dataset. The results demonstrated our 20 miRNAs achieved a better performance (AUC: 0.73) than miRNAs selected with Boruta algorithm (AUC: 0.55), a method for the automated feature extraction. Studying miRNA-mRNA associations, key miRNAs were identified with a computational approach for PC onset and progression. Further experimental validations are needed for future translational development.

Regulation of Neuroendocrine-like Differentiation in Prostate Cancer by Non-Coding RNAs

Neuroendocrine prostate cancer (NEPC) represents a variant of prostate cancer that occurs in response to treatment resistance or, to a much lesser extent, de novo. Unravelling the molecular mechanisms behind transdifferentiation of cancer cells to neuroendocrine-like cancer cells is essential for development of new treatment opportunities. This review focuses on summarizing the role of small molecules, predominantly microRNAs, in this phenomenon. A published literature search was performed to identify microRNAs, which are reported and experimentally validated to modulate neuroendocrine markers and/or regulators and to affect the complex neuroendocrine phenotype. Next, available patients’ expression datasets were surveyed to identify deregulated microRNAs, and their effect on NEPC and prostate cancer progression is summarized. Finally, possibilities of miRNA detection and quantification in body fluids of prostate cancer patients and their possible use as liquid biopsy in prostate cancer monitoring are discussed. All the addressed clinical and experimental contexts point to an association of NEPC with upregulation of miR-375 and downregulation of miR-34a and miR-19b-3p. Together, this review provides an overview of different roles of non-coding RNAs in the emergence of neuroendocrine prostate cancer.

Therapeutic Targeting of Cancer: Epigenetic Homeostasis

A large number of studies have revealed that epigenetics plays an important role in cancer development. However, the currently-developed epigenetic drugs cannot achieve a stable curative effect. Thus, it may be necessary to redefine the role of epigenetics in cancer development. It has been shown that embryonic development and tumor development share significant similarities in terms of biological behavior and molecular expression patterns, and epigenetics may be the link between them. Cell differentiation is likely a manifestation of epigenetic homeostasis at the cellular level. In this article, we introduced the importance of epigenetic homeostasis in cancer development and analyzed the shortcomings of current epigenetic treatment regimens. Understanding the dynamic process of epigenetic homeostasis in organ development can help us characterize cancer according to its differentiation stages, explore new targets for cancer treatment, and improve the clinical prognosis of patients with cancer.

miR-148a, miR-152 and miR-200b promote prostate cancer metastasis by targeting DNMT1 and PTEN expression

MicroRNAs (miRs) modulate the expression of target genes in the signal pathway on transcriptome level. The present study investigated the ‘epigenetic-based miRNA (epi-miRNA)-mRNA’ regulatory network of miR-34b, miR-34c, miR-148a, miR-152, miR-200a and miR-200b epi-miRNAs and their target genes, DNA methyltransferase (DNMT1, 3a and 3b), phosphate and tensin homolog (PTEN) and NK3 Homeobox 1 (NKX3.1), in prostate cancer (PCa) using reverse transcription-quantitative PCR. The expression level of NKX3.1 were not significantly different between the PCa, Met-PCa and control groups. However, in the PCa and Met-PCa groups, the expression level of DNMT1 was upregulated, while DNMT3a, DNMT3b and PTEN were downregulated. Overexpression of DNMT1 (~5 and ~6-fold increase in the PCa and Met-PCa groups respectively) was accompanied by a decreased expression in PTEN, indicating a potential negative association. Both groups indicated that a high level of DNMT1 is associated with the aggressiveness of cancer, and there is a a directly proportional relationship between this gene and PSA, GS and TNM staging. A significant ~2 to ~5-fold decrease in the expression levels of DNMT3a and DNMT3b was found in both groups. In the PCa group, significant associations were identified between miR-34b and DNMT1/DNMT3b; between miR-34c/miR-148a and all target genes; between miR-152 and DNMT1/DNMT3b and PTEN; and between miR-200a/b and DNMT1. In the Met-PCa group, miR-148a, miR-152 and miR-200b exhibited a significant association with all target genes. A significant negative association was identified between PTEN and DNMT1 in the Met-PCa group. It was also revealed that that miR-148a, miR-152 and miR-200b increased the expression of DNMT1 and suppressed PTEN. Furthermore, the ‘epi-miRNA-mRNA’ bidirectional feedback loop was emphasised and the methylation pattern in PCa anti-cancer therapeutics was highlighted.

miR-92a promotes proliferation and inhibits apoptosis of prostate cancer cells through the PTEN/Akt signaling pathway

MicroRNAs (miRNAs) play an important role in the development of prostate cancer (PCa). Recent studies have shown that miR-92a expression is significantly increased in various cancers including PCa. However, its specific mechanism in PCa remains unknown. The goal of this study was to investigate the effect of miR-92a expression on the function and mechanism of PCa. PCa cell lines PC-3 and LNCap were transfected with miR-92a inhibitor to reduce the expression of miR-92a, respectively. The cell proliferation, cell viability, apoptosis, cell invasion and migration ability of PCa cells were examined by CCK8 assay, cell cloning, flow cytometry, Transwell assay and scratch assay, respectively. The effects of miR-92a on PTEN/Akt signaling pathway-related factors (PI3k, Akt, p-PI3k, p-Akt, PTEN) were also observed by RT-qPCR and Western blot. Compared with the control group and NC inhibitor group, the viability, cell migration and invasion ability of PC-3 and LNCap cells were decreased and apoptosis was significantly increased after interference with miR-92a expression. In addition, the mRNA and protein levels of PTEN in PC-3 and LNCap cells in the miR-92a inhibitor group were significantly increased, while the phosphorylation levels of PI3K and AKT were significantly decreased. MiR-92a might play a key role in regulating the proliferation, migration and invasion of PCa cells through the PTEN/Akt signaling pathway. Inhibition of miR-92a expression has practical value against PCa and provides ideas for further clinical treatment of patients with PCa.

Promoter Methylation of PRKCB, ADAMTS12, and NAALAD2 Is Specific to Prostate Cancer and Predicts Biochemical Disease Recurrence

The molecular diversity of prostate cancer (PCa) has been demonstrated by recent genome-wide studies, proposing a significant number of different molecular markers. However, only a few of them have been transferred into clinical practice so far. The present study aimed to identify and validate novel DNA methylation biomarkers for PCa diagnosis and prognosis. Microarray-based methylome data of well-characterized cancerous and noncancerous prostate tissue (NPT) pairs was used for the initial screening. Ten protein-coding genes were selected for validation in a set of 151 PCa, 51 NPT, as well as 17 benign prostatic hyperplasia samples. The Prostate Cancer Dataset (PRAD) of The Cancer Genome Atlas (TCGA) was utilized for independent validation of our findings. Methylation frequencies of ADAMTS12, CCDC181, FILIP1L, NAALAD2, PRKCB, and ZMIZ1 were up to 91% in our study. PCa specific methylation of ADAMTS12, CCDC181, NAALAD2, and PRKCB was demonstrated by qualitative and quantitative means (all p < 0.05). In agreement with PRAD, promoter methylation of these four genes was associated with the transcript down-regulation in the Lithuanian cohort (all p < 0.05). Methylation of ADAMTS12, NAALAD2, and PRKCB was independently predictive for biochemical disease recurrence, while NAALAD2 and PRKCB increased the prognostic power of multivariate models (all p < 0.01). The present study identified methylation of ADAMTS12, NAALAD2, and PRKCB as novel diagnostic and prognostic PCa biomarkers that might guide treatment decisions in clinical practice.

Epigenetic dynamics in cancer stem cell dormancy

Cancer remains one of the most challenging diseases despite significant advances of early diagnosis and therapeutic treatments. Cancerous tumors are composed of various cell types including cancer stem cells capable of self-renewal, proliferation, differentiation, and invasion of distal tumor sites. Most notably, these cells can enter a dormant cellular state that is resistant to conventional therapies. Thereby, cancer stem cells have the intrinsic potential for tumor initiation, tumor growth, metastasis, and tumor relapse after therapy. Both genetic and epigenetic alterations are attributed to the formation of multiple tumor types. This review is focused on how epigenetic dynamics involving DNA methylation and DNA oxidations are implicated in breast cancer and glioblastoma multiforme. The emergence and progression of these cancer types rely on cancer stem cells with the capacity to enter quiescence also known as a dormant cellular state, which dictates the distinct tumorigenic aggressiveness between breast cancer and glioblastomas.

MicroRNA‑642a‑5p inhibits colon cancer cell migration and invasion by targeting collagen type I α1

The aim of the present study was to explore the mechanism by which microRNA (miR)-642a-5p regulates the migration and invasion of colon cancer cells via collagen type I α1 (COL1A1). The characteristics of miR-642a-5p and COL1A1 were analysed through bioinformatics. Cancer and normal tissues were collected from patients with colon cancer. miR-642a-5p- and COL1A1-overexpressing cell lines were constructed by transfection. A Dual-luciferase reporter assay was used to verify the targeting of COL1A1 by miR-642a-5p. Cell Counting Kit-8, wound healing and Transwell assays were used to detect cell viability, migration and invasion, respectively. Protein and mRNA expression levels were examined by western blotting and reverse transcription-quantitative PCR, respectively. The results revealed that miR-642a-5p expression was significantly upregulated and COL1A1 expression was downregulated in patients with colon cancer. Low levels of miR-642a-5p and high levels of COL1A1 were associated with a poor prognosis in patients with colon cancer. miR-642a-5p directly targeted the 3′-untranslated region of COL1A1 and inhibited COL1A1 expression. Overexpression of miR-642a-5p inhibited cell viability, migration, invasion and epithelial mesenchymal transition. Overexpression of COL1A1 promoted cell viability, migration, invasion and EMT, and partially reversed the inhibitory effects of miR-642a-5p on colon cancer cells. In conclusion, miR-642a-5p inhibited colon cancer cell migration, invasion and EMT by regulating COL1A1.

miR-642a-5p partially mediates the effects of lipopolysaccharide on human pulmonary microvascular endothelial cells via eEF2

Inhalation or systemic administration of lipopolysaccharide (LPS) can induce acute pulmonary inflammation and lung injury. The pulmonary vasculature is composed of pulmonary microvascular endothelial cells (PMVECs), which form a semiselective membrane for gas exchange. The miRNA miR‐642a‐5p has previously been reported to be up‐regulated in patients with acute respiratory distress syndrome; thus, here, we examined whether this miRNA is involved in the effects of LPS on PMVECs. The levels of miR‐642a‐5p and mRNA encoding eukaryotic elongation factor 2 (eEF2) were detected by quantitative RT‐PCR. Moesin and eEF2 protein levels were tested by western blot assay. Dual‐luciferase reporter assay was used to examine the relationship between miR‐642a‐5p and eEF2. Cell viability was assessed using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay, and cell permeability was analyzed using the transendothelial electrical resistance assay. We report that miR‐642a‐5p levels are significantly up‐regulated in LPS‐stimulated PMVECs, and miR‐642a‐5p contributes to LPS‐induced hyperpermeability and apoptosis of PMVECs. LPS treatment results in down‐regulation of eEF2 in PMVECs. Overexpression of eEF2, a direct target of miR‐642a‐5p, inhibited the effect of LPS on PMVECs. miR‐642a‐5p promoted LPS‐induced hyperpermeability and apoptosis by targeting eEF2. Thus, miR‐642a‐5p and eEF2 may serve as potential targets for acute lung injury/acute respiratory distress syndrome diagnosis or treatment.

Advances in Prognostic Methylation Biomarkers for Prostate Cancer

There is a major clinical need for accurate biomarkers for prostate cancer prognosis, to better inform treatment strategies and disease monitoring. Current clinically recognised prognostic factors, including prostate-specific antigen (PSA) levels, lack sensitivity and specificity in distinguishing aggressive from indolent disease, particularly in patients with localised intermediate grade prostate cancer. There has therefore been a major focus on identifying molecular biomarkers that can add prognostic value to existing markers, including investigation of DNA methylation, which has a known role in tumorigenesis. In this review, we will provide a comprehensive overview of the current state of DNA methylation biomarker studies in prostate cancer prognosis, and highlight the advances that have been made in this field. We cover the numerous studies into well-established candidate genes, and explore the technological transition that has enabled hypothesis-free genome-wide studies and the subsequent discovery of novel prognostic genes.

The Tumor Suppressive mir-148a Is Epigenetically Inactivated in Classical Hodgkin Lymphoma

DNA methylation was shown previously to be a crucial mechanism responsible for transcriptional deregulation in the pathogenesis of classical Hodgkin lymphoma (cHL). To identify epigenetically inactivated miRNAs in cHL, we have analyzed the set of miRNAs downregulated in cHL cell lines using bisulfite pyrosequencing. We focused on miRNAs with promoter regions located within or <1000 bp from a CpG island. Most promising candidate miRNAs were further studied in primary Hodgkin and Reed-Sternberg (HRS) cells obtained by laser capture microdissection. Last, to evaluate the function of identified miRNAs, we performed a luciferase reporter assay to confirm miRNA: mRNA interactions and therefore established cHL cell lines with stable overexpression of selected miRNAs for proliferation tests. We found a significant reverse correlation between DNA methylation and expression levels of mir-339-3p, mir-148a-3p, mir-148a-5p and mir-193a-5 demonstrating epigenetic regulation of these miRNAs in cHL cell lines. Moreover, we demonstrated direct interaction between miR-148a-3p and IL15 and HOMER1 transcripts as well as between mir-148a-5p and SUB1 and SERPINH1 transcripts. Furthermore, mir-148a overexpression resulted in reduced cell proliferation in the KM-H2 cell line. In summary, we report that mir-148a is a novel tumor suppressor inactivated in cHL and that epigenetic silencing of miRNAs is a common phenomenon in cHL.

MicroRNA-155-5p inhibits the invasion and migration of prostate cancer cells by targeting SPOCK1

The aim of the present study was to determine the effect of microRNA (miR)-155-5p on the expression of testican-1 (SPOCK1) and the invasion and migration of prostate cancer cells in vitro. Bioinformatics analysis and molecular biology assays revealed that SPOCK1 may be a direct target gene of miR-155-5p. In addition, a negative correlation was identified between SPCOK1 and miR-155-5p expression in prostate tumor tissues and cell lines. miR-155-5p mimic transfection inhibited SPOCK1 expression in PC3 cells and decreased cell migration and invasion abilities, while the expression of vimentin, N-cadherin, E-cadherin, β-catenin, matrix metalloproteinase (MMP)3 and MMP9 was upregulated. In summary, SPOCK1 was found to be a target gene of miR155-5p in prostate cancer, and miR-155-5p acts as a tumor-suppressor gene and may inhibit SPOCK1-mediated prostate cancer progression.

Long noncoding RNA LINC00261 suppresses prostate cancer tumorigenesis through upregulation of GATA6-mediated DKK3

Background

Prostate cancer is one of the leading causes of cancer death in males. Recent studies have reported aberrant expression of lncRNAs in prostate cancer. This study explores the role of LINC00261 in prostate cancer progression.

Methods

The differentially expressed genes, transcription factors, and lncRNAs related to prostate cancer were predicted by bioinformatics analysis. Prostate cancer tissue samples and cell lines were collected for the determination of the expression of LINC00261 by reverse transcription quantitative polymerase chain reaction. The binding capacity of LINC00261 to the transcription factor GATA6 was detected by RIP, and GATA6 binding to the DKK3 promoter region was assessed by ChIP. In addition, luciferase reporter system was used to verify whether LINC00261 was present at the DKK3 promoter. After gain- and loss-of function approaches, the effect of LINC00261 on prostate cancer in vitro and in vivo was assessed by the determination of cell proliferation, invasion and migration as well as angiogenesis.

Results

LINC00261, GATA6, and DKK3 were poorly expressed in prostate cancer. LINC00261 could inhibit transcriptional expression of DKK3 by recruiting GATA6. Overexpression of LINC00261 inhibited prostate cancer cells proliferation, migration, and invasion as well as angiogenesis, which could be reversed by silencing DKK3. Furthermore, LINC00261 could also suppress the tumorigenicity of cancer cells in vivo.

Conclusions

Our study demonstrates the inhibitory role of LINC00261 in prostate cancer progression, providing a novel biomarker for early detection of prostate cancer.

One locus with two roles: microRNA-independent functions of microRNA-host-gene locus-encoded long noncoding RNAs

Long noncoding RNAs (lncRNAs) are RNA transcripts longer than 200 nucleotides that do not code for proteins. LncRNAs play crucial regulatory roles in several biological processes via diverse mechanisms and their aberrant expression is associated with various diseases. LncRNA genes are further subcategorized based on their relative organization in the genome. MicroRNA (miRNA)-host-gene-derived lncRNAs (lnc-MIRHGs) refer to lncRNAs whose genes also harbor miRNAs. There exists crosstalk between the processing of lnc-MIRHGs and the biogenesis of the encoded miRNAs. Although the functions of the encoded miRNAs are usually well understood, whether those lnc-MIRHGs play independent functions are not fully elucidated. Here, we review our current understanding of lnc-MIRHGs, including their biogenesis, function, and mechanism of action, with a focus on discussing the miRNA-independent functions of lnc-MIRHGs, including their involvement in cancer. Our current understanding of lnc-MIRHGs strongly indicates that this class of lncRNAs could play important roles in basic cellular events as well as in diseases. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs Regulatory RNAs/RNAi/Riboswitches > Biogenesis of Effector Small RNAs.

DNMT1 maintains the methylation of miR-152-3p to regulate TMSB10 expression, thereby affecting the biological characteristics of colorectal cancer cells

Objective

DNA methyltransferases (DNMTs) take on a relevant role in epigenetic control of cancer proliferation and cell survival. However, the molecular mechanisms underlying the establishment and maintenance of DNA methylation in human cancer remain to be fully elucidated. This study was to investigate that how DNMT1 affected the biological characteristics of colorectal cancer (CRC) cells via modulating methylation of microRNA (miR)‐152‐3p and thymosin β 10 (TMSB10) expression.

Methods

DNMT1, miR‐152‐3p, and TMSB10 expression, and the methylation of miR‐152‐3p in CRC tissues and cells were detected. SW‐480 and HCT‐116 CRC cells were transfected with DNMT1 or miR‐152‐3p‐related sequences or plasmids to explore their characters in biological functions of CRC cells. The binding relationship between DNMT1 and miR‐152‐3p and the targeting relationship between miR‐152‐3p and TMSB10 were analyzed. The tumor growth was also detected in vivo.

Results

Upregulated DNMT1, TMSB10, reduced miR‐152‐3p, and methylated miR‐152‐3p were detected in CRC tissues and cells. Silenced DNMT1 or upregulated miR‐152‐3p reduced TMSB10 expression and suppressed CRC progression and tumor growth. Moreover, elevated DNMT1 could reverse the effect of miR‐152‐3p upregulation on CRC development and tumor growth. DNMT1 maintained methylation of miR‐152‐3p. TMSB10 was the direct target gene of miR‐152‐3p.

Conclusion

The study highlights that silenced DNMT1 results in non‐methylated miR‐152‐3p to depress TMSB10 expression, thereby inhibiting CRC development, which provides a new approach for CRC therapy.

MicroRNA-155 Participates in the Expression of LSD1 and Proinflammatory Cytokines in Rheumatoid Synovial Cells

MicroRNA-155 (miRNA-155) is abundant in fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA). Lysine-specific demethylase 1 (LSD1) has been found that it can ameliorate the severity of RA. Tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 are key proinflammatory cytokines implicated in the pathogenesis of RA. In our study, we investigated whether miRNA-155 participates in the expression of LSD1 and proinflammatory cytokines in rheumatoid synovial cells. First of all, flow cytometry and cell counting kit-8 analysis were employed to explore the apoptosis and proliferation of FLS, respectively. Subsequently, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was applied to probe into the level of miRNA-155 in FLS when stimulated by miRNA-155 molecules. Moreover, RT-qPCR was used to explore the relative LSD1 miRNA expression in FLS when stimulated by miRNA-155 molecules, and Western blot and immunofluorescence assay were applied to probe into the expression level of LSD1. Finally, enzyme-linked immunosorbent assay was employed to analyze the secreting level of proinflammatory cytokines in FLS when stimulated by miRNA-155 molecules. RA-FLS showed a higher apoptosis rate than normal FLS. The cell proliferation of both HFLS and MH7A cells was promoted by miRNA-155 upregulation. Meanwhile, the expression of LSD1 and proinflammatory cytokines in the FLS of RA was also changed by miRNA-155 regulation. In conclusion, miRNA-155 participates in the expression of LSD1 and proinflammatory cytokines in rheumatoid synovial cells. These findings imply a potential function and interaction of miRNA-155 and LSD1.

Comparative analysis of epi-miRNA expression levels in local/locally advanced and metastatic prostate cancer patients

Abnormal expression of enzymes involved in epigenetic mechanisms, such as DNA methyl transferases, can trigger large chaos in cellular gene expression networks and eventually lead to cancer progression. In our study, which is a pioneer in the literature that clinicopathologically evaluates the expression of 30 epi-miRNAs in prostate cancer (PCa), we investigated which of the new miRNA class epi-miRNAs could be an effective biomarker in the diagnosis and progression of PCa. In this study, the expression levels of 30 epi-miRNAs in whole blood samples from 25 control, 25 PCa and 40 metastatic PCa patients were investigated by the Quantitative Real-Time PCR method. Then, promoter methylation levels of 11 epi-miRNAs, whose expression levels were found to be significantly higher, were examined by methylation-specific qPCR method. The correlations between miRNA expression levels and clinicopathological parameters (Gleason Score (GS), PSA levels, TNM Staging) in different stages of PCa groups as well as disease-specific expression levels were examined. We found a hypomethylation in the promoter regions of miRNAs that showed a direct proportional increase with PSA levels (miR-34b/c, miR-148a, miR-152), GS's (miR-34a-5p, miR-34b/c, miR-101-2, miR-126, miR-148a, miR- 152, miR-185-5p) and T staging (miR-34a-5p, miR-34b/c, miR-101-2, miR-126, miR-140, miR-148a, miR-152, miR-185-5p) (p < 0.05). When miR-200a/b was evaluated according to clinicopathological parameters, it acted as an onco-miR in local/local advanced PCa and as a tumor-suppressor-miR in metastatic stage. This study is novel in the sense that our findings draw attention to the important role of miRNAs as diagnostic and prognostic biomarkers in PCa.

Hypermethylation of the miR-155 gene in the whole blood and decreased plasma level of miR-155 in rheumatoid arthritis

Objectives

miR-155 plays a critical role in the inflammatory process and in diseases such as rheumatoid arthritis (RA). miR155 gene expression is regulated by its gene promoter region CpG island methylation. Previous studies have shown inconsistent changes in circulating levels of mir-155 in RA patients. The aims of our study were to evaluate miR-155 levels in plasma, to investigate its gene methylation level, and to correlate these levels with RA disease activity.

Methods

One hundred and twenty-five patients with RA, and 30 age and sex-matched healthy controls (HC) were enrolled. Whole blood and plasma samples were collected and stored at -80°C until analysis. DAS28 score at the time of the blood draw was used to assess RA disease activity. The methylation status of miR-155 host gene was determined in whole blood by quantitative real-time methylation-specific PCR (qPCR). miR-155 expression levels were evaluated by quantitative reverse transcription PCR.

Results

We found significantly lower circulating miR155 levels in RA patients compared to HC. Interestingly, the miR-155 gene methylation level was significantly higher in RA patients than in HC. miR-155 levels did not correlate with ACPA or RF positivity or disease activity.

Conclusions

We show here higher miR-155 methylation in whole blood and lower plasma miR155 expression in RA patients in comparison to HC. The evaluation of miR-155 host gene methylation status or miR155 plasma level might be a potentially useful marker in RA determination.

BRAFi induced demethylation of miR-152-5p regulates phenotype switching by targeting TXNIP in cutaneous melanoma

Treatment of advanced BRAFV600-mutant melanoma using BRAF inhibitors (BRAFi) eventually leads to drug resistance and selects for highly metastatic tumor cells. We compared the most differentially dysregulated miRNA expression profiles of vemurafenib-resistant and highly-metastatic melanoma cell lines obtained from GEO DataSets. We discovered miR-152-5p was a potential regulator mediating melanoma drug resistance and metastasis. Functionally, knockdown of miR-152-5p significantly compromised the metastatic ability of BRAFi-resistant melanoma cells and overexpression of miR-152-5p promoted the formation of slow-cycling phenotype. Furthermore, we explored the cause of how and why miR-152-5p affected metastasis in depth. Mechanistically, miR-152-5p targeted TXNIP which affected metastasis and BRAFi altered the methylation status of MIR152 promoter. Our study highlights the crucial role of miR-152-5p on melanoma metastasis after BRAFi treatment and holds significant implying that discontinuous dosing strategy may improve the benefit of advanced BRAFV600-mutant melanoma patients.

A Novel Predictor Tool of Biochemical Recurrence after Radical Prostatectomy Based on a Five-MicroRNA Tissue Signature

Within five to ten years after radical prostatectomy (RP), approximately 15–34% of prostate cancer (PCa) patients experience biochemical recurrence (BCR), which is defined as recurrence of serum levels of prostate-specific antigen >0.2 µg/L, indicating probable cancer recurrence. Models using clinicopathological variables for predicting this risk for patients lack accuracy. There is hope that new molecular biomarkers, like microRNAs (miRNAs), could be potential candidates to improve risk prediction. Therefore, we evaluated the BCR prognostic capability of 20 miRNAs, which were selected by a systematic literature review. MiRNA expressions were measured in formalin-fixed, paraffin-embedded (FFPE) tissue RP samples of 206 PCa patients by RT-qPCR. Univariate and multivariate Cox regression analyses were performed, to assess the independent prognostic potential of miRNAs. Internal validation was performed, using bootstrapping and the split-sample method. Five miRNAs (miR-30c-5p/31-5p/141-3p/148a-3p/miR-221-3p) were finally validated as independent prognostic biomarkers. Their prognostic ability and accuracy were evaluated using C-statistics of the obtained prognostic indices in the Cox regression, time-dependent receiver-operating characteristics, and decision curve analyses. Models of miRNAs, combined with relevant clinicopathological factors, were built. The five-miRNA-panel outperformed clinically established BCR scoring systems, while their combination significantly improved predictive power, based on clinicopathological factors alone. We conclude that this miRNA-based-predictor panel will be worth to be including in future studies.

Genome-Wide Methylation Profiling in Canine Mammary Tumor Reveals miRNA Candidates Associated with Human Breast Cancer

Genome-wide methylation profiling is used in breast cancer (BC) studies, because DNA methylation is a crucial epigenetic regulator of gene expression, involved in many diseases including BC. We investigated genome-wide methylation profiles in both canine mammary tumor (CMT) tissues and peripheral blood mononuclear cells (PBMCs) using reduced representation bisulfite sequencing (RRBS) and found unique CMT-enriched methylation signatures. A total of 2.2-4.2 million cytosine-phosphate-guanine (CpG) sites were analyzed in both CMT tissues and PBMCs, which included 40,000 and 28,000 differentially methylated regions (DMRs) associated with 341 and 247 promoters of differentially methylated genes (DMGs) in CMT tissues and PBMCs, respectively. Genes related to apoptosis and ion transmembrane transport were hypermethylated, but cell proliferation and oncogene were hypomethylated in tumor tissues. Gene ontology analysis using DMGs in PBMCs revealed significant methylation changes in the subset of immune cells and host defense system-related genes, especially chemokine signaling pathway-related genes. Moreover, a number of CMT tissue-enriched DMRs were identified from the promoter regions of various microRNAs (miRNAs), including cfa-mir-96 and cfa-mir-149, which were reported as cancer-associated miRNAs in humans. We also identified novel miRNAs associated with CMT which can be candidates for new miRNAs associated with human BC. This study may provide new insight for a better understanding of aberrant methylation associated with both human BC and CMT, as well as possible targets for methylation-based BC diagnostic markers.

DNA-Methylation-Caused Downregulation of miR-30 Contributes to the High Expression of XPO1 and the Aggressive Growth of Tumors in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma is one of the most aggressive cancers, with high mortality in the United States. One of the important signal transduction proteins involved in the regulation of pancreatic cancer's aggressive progression is the nuclear export protein (XPO1). High expression of XPO1 has been found in pancreatic, lung, breast and other cancers and lymphomas with a poor prognosis of patients with tumors and high proliferative activity of cancer cells. Because XPO1 exports multiple tumor suppressor proteins simultaneously from the nucleus, the inhibition of XPO1 may retain multiple tumor suppressors in the nucleus, resulting in the suppression of cell proliferation and the induction of apoptosis in tumors. In this study, we found that the high expression of XPO1 in pancreatic cancer cells could be, in part, due to the methylation of the miR-30 gene, leading to the low expression level of the miR-30 family. By co-transfection of the XPO1 3'-UTR-Luc target vector with miR-30 mimic, we found that XPO1 is a direct target of the miR-30 family. We also observed that the enforced expression of the miR-30 family inhibited the expression of XPO1, resulting in the suppression of pancreatic cancer growth both in vitro and in vivo. These findings could help to design a novel therapeutic strategy for the treatment of pancreatic cancer by introducing miR-30 into cancer cells.

AKT Inhibition Modulates H3K4 Demethylase Levels in PTEN-Null Prostate Cancer

Hyperactivated AKT kinase due to loss of its negative regulator PTEN influences many aspects of cancer biology, including chromatin. AKT primarily regulates acetyl-CoA production and phosphorylates many histone-modulating enzymes, resulting in their activation or inhibition. Therefore, understanding the therapeutic impact of AKT inhibition on chromatin-related events is essential. Here, we report that AKT inhibition in prostate-specific PTEN knockout mice significantly induces di- and trimethylation of H3K4 with concomitant reduction in H3K9 acetylation. Mechanistically, we observed that AKT inhibition reduces expression of the H3K4 methylation-specific histone demethylases KDM5 family, especially KDM5B expression at transcriptional levels. Furthermore, we observed that AKT negatively regulates miR-137 levels, which transcriptionally represses KDM5B expression. Overexpression of miR-137 significantly reduced KDM5B and increased H3K4 methylation levels but failed to change AKT phosphorylation. Overall, we observed that AKT transcriptionally regulates KDM5B mainly via repression of miR-137. Our data identify a mechanism by which AKT kinase modulates the prostate cancer epigenome through regulating H3K4 methylation. Additional studies on AKT inhibition-mediated induction of H3K4 methylation will help in designing strategies to enhance the therapeutic efficacy of PI3K/AKT inhibitors.

Interplay between miRNAs and host genes and their role in cancer

MicroRNAs (miRNAs) are small endogenous non-coding functional RNAs that post-transcriptionally regulate gene expression. They play essential roles in nearly all biological processes including cell development and differentiation, DNA damage repair, cell death as well as intercellular communication. They are highly involved in cancer, acting as tumor suppressors and/or promoters to modulate cell proliferation, epithelial-mesenchymal transition and tumor invasion and metastasis. Recent studies have shown that more than half of miRNAs are located within protein-coding or non-coding genes. Intragenic miRNAs and their host genes either share the promoter or have independent transcription. Meanwhile, miRNAs work as partners or antagonists of their host genes by fine-tuning their target genes functionally associated with host genes. This review outlined the complicated relationship between intragenic miRNAs and host genes. Focusing on miRNAs known as oncogenes or tumor suppressors in specific cancer types, it studied co-expression relationships between these miRNAs and host genes in the cancer types using TCGA data sets, which validated previous findings and revealed common, tumor-specific and even subtype-specific patterns. These observations will help understand the function of intragenic miRNAs and further develop miRNA therapeutics in cancer.

A Plasma Biomarker Panel of Four MicroRNAs for the Diagnosis of Prostate Cancer

Prostate cancer is diagnosed in over 1 million men every year globally, yet current diagnostic modalities are inadequate for identification of significant cancer and more reliable early diagnostic biomarkers are necessary for improved clinical management of prostate cancer patients. MicroRNAs (miRNAs) modulate important cellular processes/pathways contributing to cancer and are stably present in body fluids. In this study we profiled 372 cancer-associated miRNAs in plasma collected before (~60% patients) and after/during commencement of treatment (~40% patients), from age-matched prostate cancer patients and healthy controls, and observed elevated levels of 4 miRNAs - miR-4289, miR-326, miR-152-3p and miR-98-5p, which were validated in an independent cohort. The miRNA panel was able to differentiate between prostate cancer patients and controls (AUC = 0.88). Analysis of published miRNA transcriptomic data from clinical samples demonstrated low expression of miR-152-3p in tumour compared to adjacent non-malignant tissues. Overexpression of miR-152-3p increased proliferation and migration of prostate cancer cells, suggesting a role for this miRNA in prostate cancer pathogenesis, a concept that was supported by pathway analysis of predicted miR-152-3p target genes. In summary, a four miRNA panel, including miR-152-3p which likely targets genes with key roles in prostate cancer pathogenesis, has the potential to improve early prostate cancer diagnosis.

A multiplatform approach identifies miR-152-3p as a common epigenetically regulated onco-suppressor in prostate cancer targeting TMEM97

Background

Prostate cancer (PCa) is a major cause of morbidity and mortality in men worldwide. MicroRNAs are globally downregulated in PCa, especially in poorly differentiated tumors. Nonetheless, the underlying mechanisms are still elusive. Herein, using combined analysis of microRNAs expression and genomewide DNA methylation, we aimed to identify epigenetically downregulated microRNAs in PCa.

Results

We found that miR-152-3p was underexpressed in PCa and that lower expression levels were associated with promoter hypermethylation in accordance with TCGA dataset analysis. Functional in vitro assays suggest that miR-152-3p suppresses cell viability and invasion potential, whereas it promotes cell cycle arrest at S and G2/M phases. Additionally, miR-152-3p expression was associated with longer disease-free survival in PCa patients from TCGA. Finally, TMEM97, which is overexpressed in PCa, was identified as a novel miR-152-3p target gene.

Conclusions

Our findings demonstrate the advantages of using a combinatory approach to identify microRNAs downregulated due to aberrant promoter methylation. MiR-152-3p downregulation and promoter methylation was found to be prevalent in primary PCa, which impairs its role in control of cell viability, cell cycle regulation and invasion.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0475-2) contains supplementary material, which is available to authorized users.

MiR-192-5p suppresses the growth of bladder cancer cells via targeting Yin Yang 1

Bladder cancer has been identified as one of the most malignant cancers with high incidence and mortality. The underlying mechanisms by which regulate the tumorigenesis of bladder cancer deserve further investigation. Here, we found that miR-192-5p was downregulated in human bladder cancer cell lines and tissues. Overexpression of miR-192-5p significantly inhibited the growth of bladder cancer cells, while depletion of miR-192-5p exerted opposite effect. Bioinformatics analysis and molecular mechanism study identified that miR-192-5p targeted the transcription factor Yin Yang 1 (YY1) and decreased the expression level of YY1. Highly expressed YY1 attenuated the potential tumor suppressive function of miR-192-5p. The expression of miR-192-5p was negatively correlated with that of YY1 in bladder cancer tissues. These results indicated that miR-192-5p might serve as a promising target in bladder cancer diagnosis and therapy.

Epigenetics and MicroRNAs in Cancer

The ability to reprogram the transcriptional circuitry by remodeling the three-dimensional structure of the genome is exploited by cancer cells to promote tumorigenesis. This reprogramming occurs because of hereditable chromatin chemical modifications and the consequent formation of RNA-protein-DNA complexes that represent the principal actors of the epigenetic phenomena. In this regard, the deregulation of a transcribed non-coding RNA may be both cause and consequence of a cancer-related epigenetic alteration. This review summarizes recent findings that implicate microRNAs in the aberrant epigenetic regulation of cancer cells.

MicroRNA-31 Function as a Suppressor Was Regulated by Epigenetic Mechanisms in Gastric Cancer

Gastric cancer is one of the most lethal malignancies worldwide. The aberrant expression of microRNA-31 (miR-31) has been reported in gastric cancer; however, its regulation mechanisms are still unclear. Here, we confirmed that miR-31 expression was significantly decreased in gastric cancer tissue and cell lines. Ectopic expression of miR-31 potentially suppresses proliferation and induced early apoptosis in gastric cancer cells. Furthermore, miR-31 expression was regulated as a result of epigenetic mechanisms. The downregulation of miR-31 was associated with promoter DNA methylation status in gastric cancer and cell lines. Moreover, we found that HDAC2 was the direct target of miR-31 by binding to 3′-UTR from the results of luciferase reporter assays, qRT-PCR, and western blotting. HDAC2 played an activation role in tumor growth, whose expression is upregulated and inversely associated with miR-31 levels. All the results suggested that miR-31 function as a crucial tumor suppressor was regulated by epigenetic mechanisms in gastric cancer. We found an epigenetic pathway loop, DNA methylation-miRNA expression-target gene-tumor progression in gastric cancer, and also provided implications for molecular diagnosis and therapeutics of gastric malignancies by detecting miR-31 as a potential target.

Implications of microRNA dysregulation in the development of prostate cancer

MicroRNAs (miRNAs) are non-coding small RNAs that target mRNA to reduce protein expression. They play fundamental roles in several diseases, including prostate cancer (PCa). A single miRNA can target hundreds of mRNAs and coordinately regulate them, which implicates them in nearly every biological pathway. Hence, miRNAs modulate proliferation, cell cycle, apoptosis, adhesion, migration, invasion and metastasis, most of them constituting crucial hallmarks of cancer. Due to these properties, miRNAs emerged as promising tools for diagnostic, prognosis and management of cancer patients. Moreover, they come out as potential targets for cancer treatment, and several efforts are being made to progress in the field of miRNA-based cancer therapy. In this review, we will summarize the recent information about miRNAs in PCa. We will recapitulate all the miRNAs involved in the androgen pathway and the biology of PCa, focusing in PCa initiation and progression. In particular, we will describe the miRNAs associated with cell proliferation, cell cycle and apoptosis in PCa, as well as invasion, adhesion and metastatic miRNAs. We will revise the recent progress made understanding the role of circulating miRNAs identified in PCa that might be useful for PCa patient stratification. Another key aspect to be discussed in this review is miRNAs’ role in PCa therapy, including the miRNAs delivery.

Meta-analysis of miRNA expression profiles for prostate cancer recurrence following radical prostatectomy

BACKGROUND

Prostate cancer (PCa) is a leading reason of death in men and the most diagnosed malignancies in the western countries at the present time. After radical prostatectomy (RP), nearly 30% of men develop clinical recurrence with high serum prostate-specific antigen levels. An important challenge in PCa research is to identify effective predictors of tumor recurrence. The molecular alterations in microRNAs are associated with PCa initiation and progression. Several miRNA microarray studies have been conducted in recurrence PCa, but the results vary among different studies.

METHODS

We conducted a meta-analysis of 6 available miRNA expression datasets to identify a panel of co-deregulated miRNA genes and overlapping biological processes. The meta-analysis was performed using the 'MetaDE' package, based on combined P-value approaches (adaptive weight and Fisher's methods), in R version 3.3.1.

RESULTS

Meta-analysis of six miRNA datasets revealed miR-125A, miR-199A-3P, miR-28-5P, miR-301B, miR-324-5P, miR-361-5P, miR-363*, miR-449A, miR-484, miR-498, miR-579, miR-637, miR-720, miR-874 and miR-98 are commonly upregulated miRNA genes, while miR-1, miR-133A, miR-133B, miR-137, miR-221, miR-340, miR-370, miR-449B, miR-489, miR-492, miR-496, miR-541, miR-572, miR-583, miR-606, miR-624, miR-636, miR-639, miR-661, miR-760, miR-890, and miR-939 are commonly downregulated miRNA genes in recurrent PCa samples in comparison to non-recurrent PCa samples. The network-based analysis showed that some of these miRNAs have an established prognostic significance in other cancers and can be actively involved in tumor growth. Gene ontology enrichment revealed many target genes of co-deregulated miRNAs are involved in "regulation of epithelial cell proliferation" and "tissue morphogenesis". Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that these miRNAs regulate cancer pathways. The PPI hub proteins analysis identified CTNNB1 as the most highly ranked hub protein. Besides, common pathway analysis showed that TCF3, MAX, MYC, CYP26A1, and SREBF1 significantly interact with those DE miRNA genes. The identified genes have been known as tumor suppressors and biomarkers which are closely related to several cancer types, such as colorectal cancer, breast cancer, PCa, gastric, and hepatocellular carcinomas. Additionally, it was shown that the combination of DE miRNAs can assist in the more specific detection of the PCa and prediction of biochemical recurrence (BCR).

CONCLUSION

We found that the identified miRNAs through meta-analysis are candidate predictive markers for recurrent PCa after radical prostatectomy.