Loss of miR-26a-5p promotes proliferation, migration, and invasion in prostate cancer through negatively regulating SERBP1. Tumour Biol. 2016;37:12843-12854. [PMID: 27449037 DOI: 10.1007/s13277-016-5158-z]

Harnessing tumor-derived exosomes: A promising approach for the expansion of clinical diagnosis, prognosis, and therapeutic outcome of prostate cancer

Prostate cancer is the second leading cause of men's death worldwide. Although early diagnosis and therapy for localized prostate cancer have improved, the majority of men with metastatic disease die from prostate cancer annually. Therefore, identification of the cellular-molecular mechanisms underlying the progression of prostate cancer is essential for overcoming controlled proliferation, invasion, and metastasis. Exosomes are small extracellular vesicles that mediate most cells' interactions and contain membrane proteins, cytosolic and nuclear proteins, extracellular matrix proteins, lipids, metabolites, and nucleic acids. Exosomes play an essential role in paracrine pathways, potentially influencing Prostate cancer progression through a wide variety of mechanisms. In the present review, we outline and discuss recent progress in our understanding of the role of exosomes in the Prostate cancer microenvironment, like their involvement in prostate cancer occurrence, progression, angiogenesis, epithelial-mesenchymal transition, metastasis, and drug resistance. We also present the latest findings regarding the function of exosomes as biomarkers, direct therapeutic targets in prostate cancer, and the challenges and advantages associated with using exosomes as natural carriers and in exosome-based immunotherapy. These findings are a promising avenue for the expansion of potential clinical approaches.

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.

SERBP1 affects the apoptotic level by regulating the expression and alternative splicing of cellular and metabolic process genes in HeLa cells

Background

RNA-binding proteins (RBPs) have important roles in orchestrating posttranscriptional regulation and modulating many tumorigenesis events. SERBP1 has been recognized as an important regulator in multiple cancers, while it remains unclear whether SERBP1-regulated gene expression at the transcriptome-wide level is significantly correlated with tumorigenesis.

Methods

We overexpressed SERBP1 in HeLa cells and explored whether SERBP1 overexpression (SERBP1-OE) affects the proliferation and apoptosis of HeLa cells. We analyzed the transcriptome-wide gene expression changes and alternative splicing changes mediated by SERBP1-OE using the transcriptome sequencing method (RNA-seq). RT-qPCR was conducted to assay SERBP1-regulated alternative splicing.

Results

SERBP1-OE induced the apoptosis of HeLa cells. The downregulated genes were strongly enriched in the cell proliferation and apoptosis pathways according to the GO analysis, including FOS, FOSB, PAK6 and RAB26. The genes undergoing at least one SERBP1-regulated alternative splicing event were enriched in transcriptional regulation, suggesting a mechanism of the regulation of gene expression, and in pyruvate and fatty acid metabolic processes critical for tumorigenesis events. The SERBP1-regulated alternative splicing of ME3, LPIN3, CROT, PDP1, SLC27A1 and ALKBH7 was validated by RT-qPCR analysis.

Conclusions

We for the first time demonstrated the cellular function and molecular targets of SERBP1 in HeLa cells at transcriptional and post-transcriptional levels. The SERBP1-regulated gene expression and alternative splicing networks revealed by this study provide important information for exploring the functional roles and regulatory mechanisms of SERBP1 in cancer development and progression.

Proteomic Analysis of Prostate Cancer FFPE Samples Reveals Markers of Disease Progression and Aggressiveness

Simple Summary

Prostate cancer (PCa) is the second most frequently diagnosed type of cancer in men. The lack of tools for accurate risk assessment is causing over-treatment of men with indolent PCa but also delayed detection of metastatic disease and thus high mortality. The aim of our study was to identify proteins related to the progression and aggressiveness of PCa that could serve as potential biomarkers for better risk stratification. To this end, we performed proteomic analysis of Formalin Fixed Paraffin Embedded (FFPE) prostate tissue specimens (n = 86) and compared them based on grade groups and biochemical recurrence status. Based on the valuable data generated by these comparisons, we have selected seven proteins (NMP1, UQCRH, HSPA9, MRPL3, VCAN, SERBP1, HSPE1) as common denominators of PCa aggressiveness and persistence that could potentially be used for the development of risk assessment tools. Notably, our observations are largely validated by transcriptomics data and literature.

Abstract

Prostate cancer (PCa) is the second most common cancer in men. Diagnosis and risk assessment are widely based on serum Prostate Specific Antigen (PSA) and biopsy, which might not represent the exact degree of PCa risk. Towards the discovery of biomarkers for better patient stratification, we performed proteomic analysis of Formalin Fixed Paraffin Embedded (FFPE) prostate tissue specimens using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Comparative analysis of 86 PCa samples among grade groups 1–5 identified 301 significantly altered proteins. Additional analysis based on biochemical recurrence (BCR; BCR+ n = 14, BCR- n = 51) revealed 197 significantly altered proteins that indicate disease persistence. Filtering the overlapping proteins of these analyses, seven proteins (NPM1, UQCRH, HSPA9, MRPL3, VCAN, SERBP1, HSPE1) had increased expression in advanced grades and in BCR+/BCR- and may play a critical role in PCa aggressiveness. Notably, all seven proteins were significantly associated with progression in Prostate Cancer Transcriptome Atles (PCTA) and NPM1NPM1, UQCRH, and VCAN were further validated in The Cancer Genome Atlas (TCGA), where they were upregulated in BCR+/BCR-. UQCRH levels were also associated with poorer 5-year survival. Our study provides valuable insights into the key regulators of PCa progression and aggressiveness. The seven selected proteins could be used for the development of risk assessment tools.

Overexpression of Nucleolin and Associated Genes in Prostate Cancer

Prostate cancer (PCa) is the second most frequent cancer and the fifth leading cause of cancer death in men worldwide. If local PCa presents a favorable prognosis, available treatments for advanced PCa display limiting benefits due to therapeutic resistances. Nucleolin (NCL) is a ubiquitous protein involved in numerous cell processes, such as ribosome biogenesis, cell cycles, or angiogenesis. NCL is overexpressed in several tumor types in which it has been proposed as a diagnostic and prognostic biomarker. In PCa, NCL has mainly been studied as a target for new therapeutic agents. Nevertheless, little data are available concerning its expression in patient tissues. Here, we investigated the expression of NCL using a new cohort from Mondor Hospital and data from published cohorts. Results were then compared with NCL expression using in vitro models. NCL was overexpressed in PCa tissues compared to the normal tissues, but no prognostic values were demonstrated. Nine genes were highly co-expressed with NCL in patient tissues and tumor prostate cell lines. Our data demonstrate that NCL is an interesting diagnostic biomarker and propose a signature of genes co-expressed with NCL.

miR-26a-5p protects against drug-induced liver injury via targeting bid

BACKGROUNDS

miR-26a-5p is a short noncoding RNA that is abnormally expressed in drug-induced liver injury (DILI), but its pathophysiologic role in the mechanism of disease in DILI is still vague.

METHODS

The expression of miR-26a-5p, viability of hepatic stellate cells (HSCs) proliferation, and apoptosis were explored via real-time PCR, CCK-8 assay, Tunel fluorescence, and flow cytometry. The expression of Bid was detected via Western blot assays, real-time PCR, and immunofluorescence. The apoptosis-associated proteins were determined through Western blot. The interaction between miR-26a-5p and Bid was measured via Dual luciferase reporter assay.

RESULTS

miR-26a-5p expression was greatly decreased in HSCs and serum treated with azithromycin, simvastatin and diclofenac sodium, respectively. Hepatocyte viability was largely suppressed while hepatocyte apoptosis was markedly increased in DILI. Correspondingly, the apoptosis-associated proteins including Bid, caspase-8 and cytochrome C in HSCs were significantly upregulated when treated with either of these drugs. Moreover, miR-26a-5p interacted with Bid, and hepatocyte proliferation and apoptosis influenced by miR-26a-5p mimics were obviously reversed when co-treated with overexpressed Bid plasmids.

CONCLUSIONS

miR-26a-5p played a protective role against DILI via targeting Bid.

Long Non-Coding RNA, Small Nucleolar RNA Host Gene 5, Inhibits the Oxidized Low-Density Lipoprotein Induced Vascular Endothelial Cell Injury by Targeting miR-26a-5p

Atherosclerosis is the major cause of cardiovascular disease, and endothelial cell injury is the primary atherogenic factor. Long non-coding RNAs (lncRNAs) are increasingly implicated as critical regulators of disease progression. Still, the role of lncRNA in endothelial cell injury is largely unknown. This issue was explored in control, ox-LDL stimulated, ox-LDL stimulated+transfected negative control vector, and ox-LDL stimulated+SNHG5 overexpression vector EA. hy926 cells. Quantitative real-time PCR used to assess the expression of SNHG5 and miR-26a-5p. Flow cytometry was used to evaluate cell apoptosis. Activity or concentration of SOD, MDA, CAT, and reactive oxygen species (ROS) was measured to assess oxidative stress. Western blotting was used to examine protein-level expression of cleaved Caspase-3, cleaved Caspase-9, and cyt-c in cytoplasm and mitochondria. Potential binding sites between SNHG5 and miR-26a-5p were predicted using Starbase software, and dual-luciferase reporter assays were used to identify target relationships. SNHG5 expression in cells following ox-LDL treatment was downregulated in EA. hy926 cells. Ox-LDL treatment promotes apoptosis, and increased C-Caspase-3, C-Caspase-9, and cytoplasmic cyt-c protein levels. MDA concentration and ROS activity were increased, while the activity of SOD and CAT was decreased. Transfection with SNHG5 reversed the effects of ox-LDL on cell apoptosis and oxidative stress. SNHG5 targeted miR-26a-5p and regulated its expression. miR-26a-5p mimics reversed SNHG5 modulation of apoptosis and oxidative stress. lncRNA SNHG5 targets to miR-26a-5p to regulate vascular endothelial cell injury induced by ox-LDL.

The 1H, 15N and 13C resonance assignments of the C-terminal domain of Serpine mRNA binding protein 1 (SERBP1)

SERBP1 is a multifunctional mRNA-binding protein that has been shown to play a regulatory role in a number of biological processes such as thrombosis, DNA damage repair, and the cellular response to nutrient deprivation. Additionally, SERBP1 is upregulated in glioblastoma, leukemia as well as liver, prostrate and ovarian cancers where it has been implicated in metastatic disease and poor patient outcomes. SERBP1 binds target mRNA, stabilizing and regulating the post-translational expression of the transcript. Since SERBP1 lacks canonical RNA-binding motifs such as RRM domains or zinc fingers, its target recognition and binding mechanisms are not well understood. Recent reports suggest that it is capable of recognizing both RNA sequence motifs and structured domains. Here we report the production and purification of the intrinsically disordered C-terminal domain of SERBP1, the assignment of the 1H, 13C, 15N backbone resonances of the protein by solution-state NMR, and secondary structure predictions. We show that the protein is not entirely disordered and identify an α-helix that was stable under the experimental conditions. This work is the first step toward understanding the structural basis underpinning the molecular mechanisms of SERBP1 functions, particularly interactions with mRNA targets.

MicroRNA-148a-3p Directly Targets SERPINE1 to Suppress EMT-Mediated Colon Adenocarcinoma Progression

Aim

This research aimed at clarifying the intracellular effect of SERPINE1 in the progression of colon adenocarcinoma (COAD) and the underlying mechanism.

Methods

We obtained the expression profile of SERPINE1 in COAD via the Starbase database and verified it on COAD tissue samples through qRT-PCR and immunoblotting, respectively. Also, miRWalk, TargetScan and miRDB databases were adopted to generate the miRNA prediction that might target SERPINE1, and the gene target miR-148a-3p was confirmed using dual-luciferase assays. The effect of SERPINE1 and miR-148a-3p on COAD was further evaluated by cell experiments. MTT assay was used to detect the change of cell proliferation ability. The invasive and migratory capability of COAD cells was examined using transwell and would healing assays. Cell apoptosis was determined through flow cytometry. The expressions of genes and EMT-associated proteins were evaluated by qRT-PCR and immunoblotting. Further lucubration of the biological relevance of SERPINE1 and miR-148a-3p was conducted using rescue experiments.

Results

We found that the expression quantities of SERPINE1 in COAD tissues and cell lines were higher than those in corresponding non-cancerous tissues and normal cells. When SERPINE1 expression is reduced, EMT process is inhibited, invasion and proliferation ability of COAD cells are obviously reduced, and apoptosis level is increased. Moreover, SERPINE1 was identified as the target gene of miR-148a-3p. When the expression of miR-148a-3p was enhanced, it was found that the expression of SERPINE1 was reduced. miR-148a-3p played the similar effect of si-SERPINE1 that suppressed the COAD progression. Additionally, we found out that SERPINE1 is validated in hindering the tumor healing effect of miR148a-3p in COAD, including cell growth and invasion.

Conclusion

Our study suggests that SERPINE1/miR-148a-3p axis has potential as prognostic markers of COAD and provides reference for the development of new therapies.

CircRNA circBACH1 (hsa_circ_0061395) serves as a miR-656-3p sponge to facilitate hepatocellular carcinoma progression through increasing SERBP1 expression

Hsa_circ_0061395(circBACH1) and SERBP1(SERPINE1 mRNA binding protein 1) have been reported to play a carcinogenic role in HCC.In this study, circBACH1, microRNA(miR)-656-3p, and SERBP1 expression levels with quantitative real-time polymerase chain reaction (qRT-PCR) in HCC tissue specimens and cells.The protein levels of SERBP1, E-Cadherin, vimentin, and N-Cadherin were detected with western blotting.Cell proliferation, migration, invasion, and apoptosis were determined with CCK-8, colony formation, transwell, and flow cytometry assays.The targeting relatio-nship between circBACH1 or SERBP1 and miR-656-3p was verified by dual-lucifer- ase reporter assay.The role of circBACH1 was validated by xenograft assay.CircBAC- H1 and SERBP1 were upregulated in HCC tissues and cells.Both circBACH1 and SERBP1 knockdown constrained proliferation, migration, invasion, and EMT(epithel-ial-mesenchymal transition), and facilitated apoptosis of HCC cells in vitro.Knockdo-wn of circBACH1 reduced HCC growth in vivo. SERBP1 overexpression partially neutralized the repressive effect of circBACH1 silencing on malignant behaviors of HCC cells.CircBACH1 sponged miR-656-3p to elevate SERBP1 expression, thereby accelerating the progression of HCC.The research provided a new evidence to support the role of circBACH1 in HCC.

Rapamycin Inhibits Glioma Cells Growth and Promotes Autophagy by miR-26a-5p/DAPK1 Axis

Background

Glioma is a common intracranial malignant tumor with high rates of invasiveness and mortality. This study aimed to investigate the mechanism of rapamycin in glioma.

Methods

U118-MG cells were treated with and without rapamycin in vivo and then collected for RNA sequencing. Differentially expressed miRNAs (DEMs) were screened and verified. MiR-26a-5p was selected for functional verification, and the target gene of miR-26a-5p was identified. The effects of miR-26a-5p on cell proliferation, cell cycle, apoptosis, and autophagy were also investigated.

Results

In total, 58 up-regulated and 41 down-regulated DEMs were identified between rapamycin-treated and untreated U118-MG cells. MiR-26-5p levels were up-regulated in U118-MG cells treated with 12.5 μM rapamycin, and death-associated protein kinase 1 (DAPK1) expression, a direct miR-26a-5p target gene, was down-regulated. Rapamycin substantially inhibited cell proliferation and cell percentage in the S phase and promoted cell apoptosis; miR-26a-5p inhibitor increased cell proliferation and cell cycle and decreased cell apoptosis; DAPK1 overexpression further induced cell proliferation, increased the cell number in the S phase, and inhibited apoptosis in glioma cells. Notably, rapamycin increased the autophagy-related Beclin1 protein expression levels and the LC3 II/I ratio.

Conclusion

Rapamycin exerts anti-tumor effects by promoting autophagy in glioma cells, which was dependent on the miR-26a-5p/DAPK1 pathway activation by rapamycin.

MicroRNA-26a inhibits cell proliferation and invasion by targeting FAM98A in breast cancer

MicroRNAs (miRNAs/miRs) play key roles in cancer progression. Extensive research has revealed that miR-26a is abnormally expressed and functions as a tumor suppressor in numerous types of cancer. Thus, the present study was undertaken to investigate the regulatory role and potential mechanism of action of miR-26a in breast cancer. Furthermore, the present study aimed to examine the alterations in miR-26a expression and its effects on human breast cancer cells. Reverse transcription-quantitative PCR was conducted to assess the differences in miR-26a expression between human breast cancer and normal breast specimens. A Cell Counting Kit-8 assay and cloning experiments were used to detect cell proliferation and clone formation. Wound healing and Transwell assays were performed to examine cell migration and invasion. A luciferase activity experiment was utilized to validate the association between miR-26a and family with sequence similarity 98 member A (FAM98A). Western blotting was conducted to detect the protein expression levels of FAM98A, sonic hedgehog signaling molecule (SHH), smoothened, frizzled class receptor (SMO) and GLI family zinc finger 1 (GLI1). The results indicated that miR-26a expression was decreased in breast carcinoma tissues and cell lines. Moreover, overexpression of miR-26a significantly suppressed cell proliferation, clone formation ability and metastasis, and it sensitized breast cancer cells to docetaxel. It was demonstrated that miR-26a directly targeted FAM98A, and that FAM98A, SHH, SMO and GLI1 expression levels were decreased in cells transfected with miR-26a mimics. Collectively, the results of the present study suggested that miR-26a negatively regulated the expression of FAM98A, indicating that it may play a key role in the suppression of breast carcinogenesis.

Small-sized extracellular vesicles (EVs) derived from acute myeloid leukemia bone marrow mesenchymal stem cells transfer miR-26a-5p to promote acute myeloid leukemia cell proliferation, migration, and invasion

Bone marrow mesenchymal stem cells (BMSCs) in acute myeloid leukemia (AML) microenvironment undergo modification that includes expression of contents in the small-sized extracellular vesicles (EVs) they secrete. This study aims to investigate whether small-sized EVs from BMSCs of AML patients regulate AML progression by modifying the expression of miR-26a-5p. Small-sized EVs from BMSCs of AML patients (AML-BMSC-EVs) or healthy controls (HC-BMSC-EVs) were isolated by ultra-centrifugation and administered to AML cells (OCI/AML-2 and THP-1). Cell proliferation, migration, and invasion were evaluated by CCK-8 assay, Transwell migration and invasion assays, respectively. Compared with HC-BMSC-EVs, AML-BMSC-EVs contained higher expression of miR-26a-5p and promoted AML cell proliferation, migration, and invasion. Inhibition of miR-26a-5p expression in AML-BMSC-EVs could abrogate the promoting effects of AML-BMSC-EVs on AML cell proliferation, migration, and invasion. Furthermore, GSK3β was a direct target of miR-26a-5p. Moreover, AML-BMSC-EVs inhibited GSK3β expression and activated Wnt/β-catenin signaling in AML cells. Additionally, GSK3β overexpression in THP-1 cells counteracted the promoting effects of AML-BMSCs-EVs on THP-1 cell proliferation, migration, and invasion. AML-BMSC-EVs promoted AML progression by transferring miR-26a-5p to AML cells and subsequently activating the Wnt/β-catenin pathway.

Critical role of miR-26a-5p/Wnt5a signaling in gambogic acid-induced inhibition of gastric cancer

Gastric cancer (GC) represents the fifth most human malignant disease and the third-most common cause of cancer-related death. Gambogic acid (GA) is a natural compound with a polyprenylated xanthone structure and possesses remarkable antitumor activity in a variety of cancer cells. However, the mechanism underlying the inhibitory effect of GA in GC is far from being completely understood. The goal of the present study is to investigate whether potential microRNAs are involved in antitumor effect of GA toward GC and to elucidate the possible mechanisms. We identified that miR-26a-5p was significantly increased by GA in GC cell lines and xenograft tumor. Downregulation of miR-26a-5p not only prevented GA-induced inhibition on GC cell growth, but also suppressed GA-induced apoptosis of GC cells. Informatics assay predicted that Wnt5a was regulated by miR-26a-5p and GA-induced downregulation of Wnt5a was prevented by anti-miR-26a-5p. Reporter gene assay showed that miR-26a-5p could negatively regulate Wnt5a through direct binding with 3'-UTR messenger RNA of Wnt5a. Thus, upregulation of Wnt5a exhibited the same action tendency for GA-induced GC cell growth and apoptosis as observed by downregulation of miR-26a-5p. In conclusion, these results indicated that the inhibitory effect of GA on GC was mediated by the upregulation of miR-26a-5p and downregulation of Wnt5a. Our study provided new clues for the potential therapeutic effect of GA against GC and highlighted the importance of miR-26a-5p/Wnt5a pathway in the regulation of GC development.

The miRNA Profile in Non-Hodgkin's Lymphoma Patients with Secondary Myelodysplasia

Myelodysplastic syndromes are a group of clonal diseases of hematopoietic stem cells and are characterized by multilineage dysplasia, ineffective hematopoiesis, peripheral blood cytopenias, genetic instability and a risk of transformation to acute myeloid leukemia. Some patients with non-Hodgkin lymphomas (NHLs) may have developed secondary myelodysplasia before therapy. Bone marrow (BM) hematopoiesis is regulated by a spectrum of epigenetic factors, among which microRNAs (miRNAs) are special. The aim of this work is to profile miRNA expression in BM cells in untreated NHL patients with secondary myelodysplasia. A comparative analysis of miRNA expression levels between the NHL and non-cancer blood disorders samples revealed that let-7a-5p was upregulated, and miR-26a-5p, miR-199b-5p, miR-145-5p and miR-150-5p were downregulated in NHL with myelodysplasia (p < 0.05). We for the first time developed a profile of miRNA expression in BM samples in untreated NHL patients with secondary myelodysplasia. It can be assumed that the differential diagnosis for blood cancers and secondary BM conditions based on miRNA expression profiles will improve the accuracy and relevance of the early diagnosis of cancerous and precancerous lesions in BM.

ARNTL2 promotes pancreatic ductal adenocarcinoma progression through TGF/BETA pathway and is regulated by miR-26a-5p

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies and the therapeutic outcomes remain undesirable. Increasing evidence shows that aryl hydrocarbon receptor nuclear translocator like 2 (ARNTL2) plays crucial roles in tumorigenesis of multiple tumors. However, the expression status and functions of ARNTL2 in PDAC remain elusive. Here we showed that ARNTL2 expression was markedly upregulated in PDAC tissues and cell lines. elevated expression of ARNTL2 was positively related to unfavorable prognosis. Knockdown of ARNTL2 could suppress motility and invasive ability of PDAC cells in vitro, as well as tumor development in vivo. In addition, microRNA-26a-5p (miR-26a-5p) was identified as the crucial specific arbitrator for ARNTL2 expression and the expression of miR-26a-5p was inversely correlated with ARNTL2 expression in PDAC tissues. Functionally, elevated expression of miR-26a-5p was found to inhibit the proliferation, migration, and invasion of PDAC cells in vitro, while ARNTL2 increased expression could partially abolish the suppressive effect of miR-26a-5p. Mechanism study indicated that elevated expression of miR-26a-5p suppressed TGF/BETA signaling pathway by targeting ARNTL2 in PDAC cells. In conclusion, our data suggested that ARNTL2 acted as an oncogene to regulate PDAC growth. MiR-26a-5p/ARNTL2 axis may be a novel therapeutic candidate target in PDAC treatment.

The RNA-binding protein SERBP1 functions as a novel oncogenic factor in glioblastoma by bridging cancer metabolism and epigenetic regulation

BACKGROUND

RNA-binding proteins (RBPs) function as master regulators of gene expression. Alterations in RBP expression and function are often observed in cancer and influence critical pathways implicated in tumor initiation and growth. Identification and characterization of oncogenic RBPs and their regulatory networks provide new opportunities for targeted therapy.

RESULTS

We identify the RNA-binding protein SERBP1 as a novel regulator of glioblastoma (GBM) development. High SERBP1 expression is prevalent in GBMs and correlates with poor patient survival and poor response to chemo- and radiotherapy. SERBP1 knockdown causes delay in tumor growth and impacts cancer-relevant phenotypes in GBM and glioma stem cell lines. RNAcompete identifies a GC-rich region as SERBP1-binding motif; subsequent genomic and functional analyses establish SERBP1 regulation role in metabolic routes preferentially used by cancer cells. An important consequence of these functions is SERBP1 impact on methionine production. SERBP1 knockdown decreases methionine levels causing a subsequent reduction in histone methylation as shown for H3K27me3 and upregulation of genes associated with neurogenesis, neuronal differentiation, and function. Further analysis demonstrates that several of these genes are downregulated in GBM, potentially through epigenetic silencing as indicated by the presence of H3K27me3 sites.

CONCLUSIONS

SERBP1 is the first example of an RNA-binding protein functioning as a central regulator of cancer metabolism and indirect modulator of epigenetic regulation in GBM. By bridging these two processes, SERBP1 enhances glioma stem cell phenotypes and contributes to GBM poorly differentiated state.

Transcriptomic analysis reveals the oncogenic role of S6K1 in hepatocellular carcinoma

The p70 ribosomal protein S6 kinase 1 (S6K1), a serine/threonine kinase, is commonly overexpressed in a variety of cancers. However, its expression level and functional roles in hepatocellular carcinoma (HCC), which ranks as the third leading cause of cancer-related death worldwide, is still largely unknown. In the current report, we show the in vivo and in vitro overexpression of S6K1 in HCC. In the functional analysis, we demonstrate that S6K1 is required for the proliferation and colony formation abilities in HCC. By using comparative transcriptomic analysis followed by gene ontology enrichment analysis and Ingenuity Pathway Analysis, we find that the depletion of S6K1 can elevate the expression of a cluster of apoptotic genes, tumor suppressor genes and immune responsive genes. Moreover, the knockdown of S6K1 is predicted to reduce the tumorigenicity of HCC through the regulation of hubs of genes including STAT1, HDAC4, CEBPA and ONECUT1. In conclusion, we demonstrate the oncogenic role of S6K1 in HCC, suggesting the possible use of S6K1 as a therapeutic target for HCC treatment.

Circular RNA ciRS-7 promotes tube formation in microvascular endothelial cells through downregulation of miR-26a-5p

Atherosclerosis is one of the most common and crucial heart diseases involving the heart and brain. At present, atherosclerosis and its major complications comprise the leading causes of death worldwide. Our purpose was to identify the role of ciRS-7 in atherosclerosis. Tubulogenesis of HMEC-1 cell was evaluated utilizing tube formation assay. Cell Counting Kit-8 assay and flow cytometry were utilized to test viability and apoptosis. Migration assay was utilized to determine the migration capacity of experimental cells. Western blot was applied to examine apoptosis and tube formation-associated protein expression. In addition, the above experiments were repeated when silencing ciRS-7, overexpressing ciRS-7, and upregulating miR-26a-5p. HMEC-1 cells formed tube-like structures over time. Silencing ciRS-7 suppressed viability, migration, and tube formation but promoted apoptosis. Oppositely, overexpressing ciRS-7 reversed the effect in HMEC-1 cells. miR-26a-5p expression was elevated by silencing ciRS-7 and reduced by overexpressing ciRS-7. Moreover, overexpressing ciRS-7 facilitated viability, migration, and tube formation via upregulating miR-26a-5p. Conclusively, overexpressing ciRS-7 mobilized phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway and suppressed c-Jun N-terminal kinase (JNK)/p38 pathway. ciRS-7 exerted influence on apoptosis, viability, migration, and tube formation through mediating PI3K/AKT and JNK/p38 pathways by miR-26a-5p downregulation in HMEC-1 cells.

Overexpression of miR-26a-5p Suppresses Tau Phosphorylation and Aβ Accumulation in the Alzheimer's Disease Mice by Targeting DYRK1A

OBJECTIVE

It is reported that miR-26a-5p could regulate neuronal development, but its underlying mechanisms in Alzheimer's disease (AD) progression is unclear.

METHODS

APP (swe)/PS1 (ΔE9) transgenic mice served as AD mice. Morris water maze test was used to measure the spatial learning and memory ability of mice. The expressions of miR-26a-5p, DYRK1A, phosphorylated-Tau, Aβ40, and Aβ42 were detected. The relationship between miR- 26a-5p and DYRK1A was explored using dual luciferase reporter assay. The effects of miR-26a- 5p on AD mice was determined.

RESULTS

AD mice walked a lot of wrong ways to find the platform area and the latency time to reach the platform was longer. There was low expression of MiR-26a-5p in AD mice. Overexpression of miR-26a-5p inhibited Tau phosphorylation and Aβ accumulation. MiR-26a-5p negatively regulated DYRK1A via targeting its 3'UTR. In vivo, increased miR-26a-5p down-regulated Aβ40, Aβ42, p-APP and p-Tau levels in AD mice through decreasing DYRK1A. Meanwhile, the swimming path and the latency time, to reach the platform, was shorten after enhancing miR-26a-5p expression.

CONCLUSION

Overexpression of miR-26a-5p could repress Tau phosphorylation and Aβ accumulation via down-regulating DYRK1A level in AD mice.

Complex interactomes and post-translational modifications of the regulatory proteins HABP4 and SERBP1 suggest pleiotropic cellular functions

The 57 kDa antigen recognized by the Ki-1 antibody, is also known as intracellular hyaluronic acid binding protein 4 and shares 40.7% identity and 67.4% similarity with serpin mRNA binding protein 1, which is also named CGI-55, or plasminogen activator inhibitor type-1-RNA binding protein-1, indicating that they might be paralog proteins, possibly with similar or redundant functions in human cells. Through the identification of their protein interactomes, both regulatory proteins have been functionally implicated in transcriptional regulation, mRNA metabolism, specifically RNA splicing, the regulation of mRNA stability, especially, in the context of the progesterone hormone response, and the DNA damage response. Both proteins also show a complex pattern of post-translational modifications, involving Ser/Thr phosphorylation, mainly through protein kinase C, arginine methylation and SUMOylation, suggesting that their functions and locations are highly regulated. Furthermore, they show a highly dynamic cellular localization pattern with localizations in both the cytoplasm and nucleus as well as punctuated localizations in both granular cytoplasmic protein bodies, upon stress, and nuclear splicing speckles. Several reports in the literature show altered expressions of both regulatory proteins in a series of cancers as well as mutations in their genes that may contribute to tumorigenesis. This review highlights important aspects of the structure, interactome, post-translational modifications, sub-cellular localization and function of both regulatory proteins and further discusses their possible functions and their potential as tumor markers in different cancer settings.

miR-26a promotes hepatocellular carcinoma invasion and metastasis by inhibiting PTEN and inhibits cell growth by repressing EZH2

A previous study revealed that therapeutic miR-26a delivery suppresses tumorigenesis in a murine liver cancer model, whereas we found that forced miR-26a expression increased hepatocellular carcinoma (HCC) cell migration and invasion, which prompted us to characterize the causes and mechanisms underlying enhanced invasion due to ectopic miR-26a expression. Gain-of-function and loss-of-function experiments demonstrated that miR-26a promoted migration and invasion of BEL-7402 and HepG2 cells in vitro and positively modulated matrix metalloproteinase (MMP)-1, MMP-2, MMP-9, and MMP-10 expression. In addition, exogenous miR-26a expression significantly enhanced the metastatic ability of HepG2 cells in vivo. miR-26a negatively regulated in vitro proliferation of HCC cells, and miR-26a overexpression suppressed HepG2 cell tumor growth in nude mice. Further studies revealed that miR-26a inhibited cell growth by repressing the methyltransferase EZH2 and promoted cell migration and invasion by inhibiting the phosphatase PTEN. Furthermore, PTEN expression negatively correlated with miR-26a expression in HCC specimens from patients with and without metastasis. Thus, our findings suggest for the first time that miR-26a promotes invasion/metastasis by inhibiting PTEN and inhibits cell proliferation by repressing EZH2 in HCC. More importantly, our data also suggest caution if miR-26a is used as a target for cancer therapy in the future.

Prostate carcinoma cell-derived exosomal MicroRNA-26a modulates the metastasis and tumor growth of prostate carcinoma

Prostate carcinoma may develop into metastatic castration-resistant prostate carcinoma (mCRPC) after endocrine therapy. Exosomal microRNAs play an important role in the regulation of tumor microenvironment. Our study aimed to investigate the effect of exosomal miR-26a on tumor phenotype of prostate carcinoma. Low-grade prostate carcinoma cell line (LNCAP) and mCRPC cell line (PC-3) were treated as experimental subjects according to their miR-26a expressions. Wound healing, transwell and colony-forming unit assays were performed after miR-26a mimic/inhibitor transfection. Then, exosomes were isolated from LNCAP and PC-3 cells, and the levels of exosomal miR-26a were determined. After co-culture of LNCAP (PC-3) cells with PC-3 (LNCAP) exosomes, changes in malignant behaviors were measured. Moreover, LNCAP/PC-3 exosomes were injected into xenograft tumor mice to determine effects of the exosomes on tumorigenicity of LNCAP and PC-3 cells. MiR-26a showed a potently inhibitory effect on cell proliferation, migration and invasion of LNCAP and PC-3 cells. LNCAP exosomes had a higher miR-26a level, compared with PC-3 exosomes. Overexpression of miR-26a attenuated the enhanced malignant behavior of LNCAP cells induced by PC-3 exosomes, and miR-26a inhibition could reverse the inhibitory effects of LNCAP exosomes on PC-3 cells. Exosomal miR-26a could significantly alter the expressions of epithelial-mesenchymal transition (EMT)-related factors. Moreover, LNCAP exosomes suppressed the tumorigenicity of PC-3 cells, while PC-3 exosomes could promote the tumorigenicity of LNCAP cells. Our data suggest that exosomal miR-26a derived from prostate carcinoma cells had a suppressive effect on the metastasis and tumor growth of prostate carcinoma.

LncRNA SNHG5 promotes growth and invasion in melanoma by regulating the miR-26a-5p/TRPC3 pathway

INTRODUCTION

Melanoma has been reported as the most common malignancy in skin cancer. The small nucleolar RNA host gene 5 (SNHG5), an lncRNA, has been proven as a vital regulator in several types of carcinoma. This study was designed to investigate the detailed roles and possible mechanisms of SNHG5 in melanoma progression.

METHODS

Quantitative real-time PCR (qRT-PCR) analysis was conducted to detect the expression levels of SNHG5, miR-26a-5p and transient receptor potential, canonical 3 (TRPC3) mRNA in melanoma tissues and cells. CCK-8 assay was used to measure the cell viability. Flow cytometry assays were performed to determine the cell cycle distribution and apoptosis. The invasive ability was assessed by a 24-well Transwell insert. Western blot analysis was employed to evaluate the protein expression of TRPC3. Dual luciferase reporter assay, RNA immunoprecipitation (RIP) assay, and RNA pull-down assay were applied to identify the interactions among SNHG5, miR-26a-5p and TRPC3.

RESULTS

The results showed that SNHG5 expression was increased in melanoma tumor tissues and cell lines. Higher SNHG5 expression was correlated with advanced pathogenic status. Moreover, SNHG5 could serve as a molecular sponge of miR-26a-5p. SNHG5 downregulation repressed proliferation, promoted apoptosis, and decreased invasion in melanoma cells, while these effects were greatly counteracted by miR-26a-5p inhibitor. Furthermore, miR-26a-5p directly targeted TRPC3 to suppress its expression, and this effect was aggravated following SNHG5 downregulation. Also, TRPC3 depletion exerted similar tumor-suppressive functions as SNHG5 knockdown.

CONCLUSION

SNHG5 promoted melanoma development by inhibiting miR-26a-5p and facilitating TRPC3 expression, highlighting the potential of SNHG5 as a novel target therapy for melanoma.

MiR-26a-5p potentiates metastasis of human lung cancer cells by regulating ITGβ8- JAK2/STAT3 axis

Most lung cancer patients die of metastasis. Recent studies have indicated that dysregulated microRNAs (miRNAs) are involved not only in tumorigenesis, but also in metastasis. In the present study, we found that over-expression of miR-26a-5p potentiated the migration and invasion of lung cancer cells evidenced by wound healing assay and transwell assay, and metastasis-related genes MMP-9 and CD44 were up-regulated. We identified integrin-beta8 (ITGβ8) as a novel target of miR-26a, and ITGβ8 expression was negatively correlated with miR-26a-5p expression in lung cancer specimens. Mechanism study showed that miR-26a-5p enhanced lung cancer cell metastasis via activation of Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway, and ITGβ8 mediated the activation of JAK2/STAT3 pathway by miR-26a-5p. By using in vivo imaging technology, we found that miR-26a-5p enhanced both tumor growth and metastasis in vivo; and activated JAK2/STAT3 pathway. Taken together, our results demonstrated that miR-26a-5p potentiated lung cancer cell metastasis via JAK2/STAT3 pathway by targeting ITGβ8. This finding provides insights into the mechanism underlying miRNAs regulation on lung cancer metastasis; and suggests miR-26a-5p as a therapeutic target for lung cancer treatment.

miR-26a induced the suppression of tumor growth of cholangiocarcinoma via KRT19 approach

Background and Aims

KRT19 was identified as one of the key biomarkers for distinguishing cholangiocarcinoma (CCA) and hepatocellular carcinoma. The detailed role of miRNAs involved in the oncogenic incident of KRT19 was poor investigated.

Results

Based on prediction and validation, miR-26a was inversely correlated with KRT19 in patients’ tissues samples and biopsies. Ectopic expression of miR-26a dramatically suppressed cell proliferation and tumor growth in vitro and in vivo. Knock-down miR-26a could induce an increasing population of SP cells by promoting KRT19 expression. The KRT19 was also suppressed via directly binding at 3′UTR region by miR-26a.

Materials and Methods

Bioinformatics prediction was first applied to screening the potential miRNA involved. RT-PCR, Immunohistochemistry and Western blot were used to examine the expression of miRNAs and candidate genes in 65 pairs of cholangiocarcinoma. The loss-and gain-function assay was employed to detect the role of certain miRNA in vitro and vivo. Side-population (SP) cells were detected and sorted by flow cytometry.

Conclusions

Aberrant decreased miR-26a could promote cell proliferation by regulating KRT19 which play important roles in the pathogenesis of CCA.

Downregulation of miR‑205 is associated with glioblastoma cell migration, invasion, and the epithelial-mesenchymal transition, by targeting ZEB1 via the Akt/mTOR signaling pathway

Glioblastoma (GBM) is the most common type of malignant brain tumor. In spite of recent advancements in surgical techniques, chemotherapy, and radiation therapy, patients with GBM often face a dire prognosis. MicroRNAs have been shown to modulate the aggressiveness of various cancers, and have emerged as possible therapeutic agents for the management of GBM. miR‑205 is dysregulated in glioma and act as a prognostic indicator. However, the role of miR‑205 in the development of GBM has not been elucidated. To better understand the pathogenesis of GBM, we examine the biological significance and molecular mechanisms of miR‑205 in GBM cells. Zinc finger E-box binding homeobox 1 (ZEB1) has been shown to regulate the epithelial-mesenchymal transition (EMT), which is strongly associated with GBM malignancy. In the present study, we show miR‑205 expression is reduced in GBM tissues and cell lines, and ZEB1 expression is inversely correlated with miR‑205 expression. We also show ZEB1 is a downstream target of miR‑205 and the Akt/mTOR signaling pathway is activated when miR‑205 interacts with ZEB1. Increased activity of miR‑205 in GBM cells significantly inhibits migration and invasion, and prevents EMT. Furthermore, overexpression of ZEB1 partially abolishes these inhibitory effects of miR‑205. We show that miR‑205 negatively regulates the expression of ZEB1 in GBM, inhibits cell migration and invasion, and prevents EMT, at least in part through the inhibition of the activation of the Akt/mTOR signaling pathway. Our results indicate miR‑205 may be an efficacious therapeutic agent in the treatment of GBM.

The potential of microRNAs as human prostate cancer biomarkers: A meta-analysis of related studies

Prostate cancer (PC) is a very important kind of male malignancies. When PC evolves into a stage of hormone resistance or metastasis, the fatality rate is very high. Currently, discoveries and advances in miRNAs as biomarkers have opened the potential for the diagnosis of PC, especially early diagnosis. miRNAs not only can noninvasively or minimally invasively identify PC, but also can provide the data for optimization and personalization of therapy. Moreover, miRNAs have been shown to play an important role to predict prognosis of PC. The purpose of this meta‐analysis is to integrate the currently published expression profile data of miRNAs in PC, and evaluate the value of miRNAs as biomarkers for PC. All of relevant records were selected via electronic databases: Pubmed, Embase, Cochrane, and CNKI based on the assessment of title, abstract, and full text. we extracted mean ± SD or fold change of miRNAs expression levels in PC versus BPH or normal controls. Pooled hazard ratios (HRs) with 95% confidence intervals (CI) for overall survival (OS) and recurrence‐free survival (RFS), were also calculated to detect the relationship between high miRNAs expression and PC prognosis. Selected 104 articles were published in 2007‐2017. According to the inclusion criteria, 104 records were included for this meta‐analysis. The pooled or stratified analyze showed 10 up‐regulated miRNAs (miR‐18a, miR‐34a, miR‐106b, miR‐141, miR‐182, miR‐183, miR‐200a/b, miR‐301a, and miR‐375) and 14 down‐regulated miRNAs (miR‐1, miR‐23b/27b, miR‐30c, miR‐99b, miR‐139‐5p, miR‐152, miR‐187, miR‐204, miR‐205, miR‐224, miR‐452, miR‐505, and let‐7c) had relatively good diagnostic and predictive potential to discriminate PC from BPH/normal controls. Furthermore, high expression of miR‐32 and low expression of let‐7c could be used to differentiate metastatic PC from local/primary PC. Additional interesting findings were that the expression profiles of five miRNAs (miR‐21, miR‐30c, miR‐129, miR‐145, and let‐7c) could predict poor RFS of PC, while the evaluation of miR‐375 was associated with worse OS. miRNAs are important regulators in PC progression. Our results indicate that miRNAs are suitable for predicting the different stages of PC. The detection of miRNAs is an effective way to control patient's prognosis and evaluate therapeutic efficacy. However, large‐scale detections based on common clinical guidelines are still necessary to further validate our conclusions, due to the bias induced by molecular heterogeneity and differences in study design and detection methods.

Identification and Characterization of MicroRNAs in the Goat (Capra hircus) Rumen during Embryonic Development

The rumen is an important digestive organ in ruminants. Numerous regulatory factors including microRNAs (miRNAs) are involved in embryonic organ development. In the present study, miRNAs expressed in the rumens of goats (Capra hircus) and their potential roles in the pathways involved in rumen development were identified using high-throughput sequencing. Histological morphology revealed a distinct difference in each layer of rumen during the period from embryonic day 60 (E60) to embryonic day 135 (E135). We determined the expression profiles of miRNAs in the goat rumen, and identified 423 known miRNAs and 559 potentially novel miRNAs in the E60 and E135 embryonic rumen, respectively. Bioinformatics analysis annotated the 42 differentially expressed miRNAs and the top 10 most highly expressed miRNAs of the two libraries to 48 and 38 gene ontology categories, as well as to 168 and 71 Kyoto Encyclopedia of Genes and Genomes pathways, respectively. The expression patterns of eight randomly selected miRNAs were validated by stem-loop quantitative reverse transcription PCR, suggesting that the sequencing data were reliable. We profiled the genome-wide expression of rumen-expressed miRNAs at different prenatal stages of rumen tissues, revealing that a subset of miRNAs might play important roles in the formation of the rumen layers. Taken together, these findings will aid the investigation of dominant rumen-related miRNA sets and help understand the genetic control of rumen development in goats.

Discovering the miR-26a-5p Targetome in Prostate Cancer Cells

Purpose. miR-26a-5p is a tumor suppressor (TS) miRNA often downregulated in several tumor tissues and tumor cell lines. In this work, we performed the re-expression of the miR-26a-5p in DU-145 prostate cancer cells to collect genes interacting with miR-26a-5p and analyzed their integration in the tumorigenesis related pathways.

Methods. The transfection of DU-145 prostate cancer cells with miR-26a-5p was done using nucleofection. The biological effects induced by miR-26a-5p re-expression were detected with routine assays for cell proliferation, cell cycle, survival, apoptosis and cell migration. The miRNA pull out technique was used to collect and next generation sequencing to identify the complete repertoire of the miR-26a-5p targets (miR-26a-5p/targetome). TargetScan 7, PITA and RNA22 were used to find the predicted miR-26a-5p targets in the miR-26a-5p/targetome. Gene set enrichment analysis were used to integrate target genes in KEGG pathways and Protein-Protein Interaction networks (PPINs) and modules were built.

Results. miR-26a-5p exerted an anti-proliferative effect acting at several levels, by decreasing survival and migration and inducing both cell cycle block and apoptosis. The analysis of the miR-26a-5p/targetome showed that 1423 (1352 coding and 71 non-coding) transcripts interacted with miR-26a-5p. Filtering the miR-26a-5p/targetome with prediction algorithms, 628 out of 1353 transcripts were miR-26a-5p predicted targets and 73 of them were already validated miR-26a-5p targets. Finally, miR-26a-5p targets were involved in 22 KEGG pathways and 20 significant protein-protein interaction modules

Conclusion. The TS-miR-26a-5p/targetome is a platform that shows both unknown and known miRNA/target interactions thus offering the possibility to validate genes and discover pathways in which these genes could be involved.

MicroRNA-26a inhibits proliferation and metastasis of human hepatocellular carcinoma by regulating DNMT3B-MEG3 axis

miR-26a is known to play an important oncosuppressive role in HCC. However, its regulatory role and relationship with other non-coding RNAs is less clear. In the present study, we report that the expression levels of miR-26a and long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3) were frequently downregulated in HCC tissues compared to matched non-malignant tissues. In addition, the expression levels of miR-26a and MEG3 were negatively correlated with the tumor sizes and TNM clinical stage in HCC patients. Overexpression of miR-26a significantly reduced the capacity of proliferation, invasion and migration of HCC cells. Moreover, we demonstrated that DNA methyltransferase 3b (DNMT3B) was a direct target gene of miR-26a. Overexpression of miR-26a suppressed the expression level of DNMT3B. Inhibited expression of DNMT3B showed similar tumor suppressive effects induced by miR-26a upregulation, and resulted in the upregulation of MEG3. Furthermore, we found that the expression levels of DNMT3B were upregulated in the HCC tissues compared with non-malignant tissues, and it was inversely correlated with miR-26a and MEG3 in HCC tissues. Thus, these results provided a plausible link between the observed reduction of miR-26a and MEG3 in HCCs. Together, the present study added miR-26a/DNMT3B/MEG3 axis to the complex mechanisms of HCC development.

MiR-218 suppresses the metastasis and EMT of HCC cells via targeting SERBP1

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related deaths worldwide. Although many efforts for treating HCC have been made, the survival rate remains unsatisfied. Accumulating evidence indicates that microRNA-218 (miR-218) functions as a tumor suppressor and involves in many biological processes such as tumor initiation, development, and metastasis in certain types of human cancers. However, the potential function and underlying molecular mechanism of miR-218 in HCC still remains to be elucidated. Since HCC is a genetic disease, exploring the mechanisms of the pathogeny and integration are essential for the discovery of novel treatment targets for HCC. Therefore, the aim of the present study was to investigate the abnormal expression level of miR-218 in clinical HCC tissues and HCC cells, and to evaluate its function and underlying mechanisms in HCC. Our results revealed that miR-218 expression was significantly downregulated in HCC tissues and cell lines. Gain-of-function and loss-of-function assays indicated that forced expression of miR-218 in HCC cells inhibited cell migration/invasion and reversed epithelial-mesenchymal transition (EMT) to mesenchymal-epithelial transition (MET), while deletion of miR-218 promoted cell migration/invasion and contributed to the EMT phenotype formation. Bioinformatics analysis and luciferase reporter assay confirmed that serpine mRNA binding protein 1 (SERBP1) was a target gene of miR-218 and rescue assay further confirmed that SERBP1 involved in the function of miR-218 in HCC. All these results suggested that miR-218/SERBP1 signal pathway could inhibit the malignant phenotype formation and that targeting this pathway may be a potential novel way for HCC therapeutics.

MiR-26a enhances invasive capacity by suppressing GSK3β in human lung cancer cells

Lung cancer is the common cause of death from cancer, and most lung cancer patients die of metastasis. MicroRNAs (miRNAs) function as either oncogenes or tumor suppressors, playing crucial role not only in tumorigenesis, but also in tumor invasion and metastasis. There are several studies showed that miR-26a is involved in carcinogenesis, however, its role in tumor metastasis need to be elucidated. In this study, we showed that ectopic expression of miR-26a enhanced migration and invasion of lung cancer cells. Glycogen synthase kinase-3β (GSK3β) was identified as a direct target of miR-26a. GSK3β expression negatively correlated with miR-26a expression in lung cancer tissues. Silencing of GSK3β achieved similar effect as miR-26a over-expression; over-expression of GSK3β reversed the enhanced effect of miR-26a on lung cancer cell migration and invasion. Further study indicated that miR-26a increased β-catenin expression and nuclear translocation. C-myc and cyclin D1, the downstream genes of β-catenin, were also up-regulated by miR-26a. Furthermore, xenograft study showed that miR-26a promoted lung cancer cell growth in vivo, and suppressed GSK3β expression. Collectively, our results demonstrated that miR-26a enhanced metastatic potential of lung cancer cells via activation of β-catenin pathway by targeting GSK3β, suggesting the potential applicability of miR-26a as a target for cancer treatment.

miR-26a-5p suppresses tumor metastasis by regulating EMT and is associated with prognosis in HCC

OBJECTIVE

To determine the role of miR-26a-5p in tumor invasion and metastasis in hepatocellular carcinoma (HCC).

METHODS

We evaluated miR-26a-5p expression in HCC tissues by quantitative PCR and then analyzed its clinical significance using a Cox regression model. Transwell and nude mouse models were used to examine tumor metastasis in vitro and in vivo, respectively. The relationship between miR-26a-5p and epithelial-mesenchymal transition was also investigated by q-PCR and western blot.

RESULTS

Strong downregulation of miR-26a-5p was observed in tumor tissues compared to paired adjacent normal tissues. Moreover, patients with low miR-26a-5p expression had a significantly poorer prognosis than those with high expression. The multivariate analysis indicated that miR-26a-5p expression was an independent prognostic indicator. The experimental transwell model and athymic mouse model revealed that miR-26a-5p depressed tumor metastasis in vitro and in vivo, respectively. In addition, the decreased miR-26a-5p level observed in HCC was associated with reduced E-cadherin expression and upregulation of vimentin, which affects the molecular mechanism of EMT.

CONCLUSION

Downregulation of miR-26a-5p promotes tumor metastasis by targeting EMT and influences the prognosis of HCC patients. Therefore, miR-26a-5p has potential as a new biomarker and therapeutic target.

MiR-26a and miR-138 block the G1/S transition by targeting the cell cycle regulating network in prostate cancer cells

PURPOSE

The tumor-suppressive microRNAs miR-26a and miR-138 are significantly down-regulated in prostate cancer (PCa) and have been identified as direct regulators of enhancer of zeste homolog 2 (EZH2), which is a known oncogene in PCa. In the present study, the influence of miR-26a and miR-138 on EZH2 and cellular function including the impact on the cell cycle regulating network was evaluated in PCa cells.

METHODS

PC-3 and DU-145 PCa cells were transfected with 100 nM of miRNA mimics, siRNA against EZH2 (siR-EZH2) or control constructs for 4 h. Analyses of gene expression and cellular function were conducted 48 h after transfection.

RESULTS

Both miRNAs influenced the EZH2 expression and activity only marginally, whereas siR-EZH2 led to a notable decrease of the EZH2 expression and activity. Both miRNAs inhibited short- and/or long-term proliferation of PCa cells but showed no effect on viability and apoptosis. In PC-3 cells, miR-26a and miR-138 caused a significant surplus of cells in the G0/G1 phase of 6 and 12 %, respectively, thus blocking the G1/S-phase transition. Treatment with siR-EZH2 was without substantial influence on cellular function and cell cycle. Therefore, alternative target genes involved in cell cycle regulation were identified in silico. MiR-26a significantly diminished the expression of its targets CCNE1, CCNE2 and CDK6, whereas CCND1, CCND3 and CDK6 were suppressed by their regulator miR-138.

CONCLUSIONS

The present findings suggest an anti-proliferative role for miR-26a and miR-138 in PCa by blocking the G1/S-phase transition independent of EZH2 but via a concerted inhibition of crucial cell cycle regulators.