Cooperative and individualistic functions of the microRNAs in the miR-23a~27a~24-2 cluster and its implication in human diseases

Regulation of antitumor miR-144-5p targets oncogenes: Direct regulation of syndecan-3 and its clinical significance

In the human genome, miR-451a, miR-144-5p (passenger strand), and miR-144-3p (guide strand) reside in clustered microRNA (miRNA) sequences located within the 17q11.2 region. Low expression of these miRNAs is significantly associated with poor prognosis of patients with renal cell carcinoma (RCC) (miR-451a: P = .00305; miR-144-5p: P = .00128; miR-144-3p: P = 9.45 × 10-5 ). We previously reported that miR-451a acted as an antitumor miRNA in RCC cells. Involvement of the passenger strand of the miR-144 duplex in the pathogenesis of RCC is not well understood. Functional assays showed that miR-144-5p and miR-144-3p significantly reduced cancer cell migration and invasive abilities, suggesting these miRNAs acted as antitumor miRNAs in RCC cells. Analyses of miR-144-5p targets identified a total of 65 putative oncogenic targets in RCC cells. Among them, high expression levels of 9 genes (FAM64A, F2, TRIP13, ANKRD36, CENPF, NCAPG, CLEC2D, SDC3, and SEMA4B) were significantly associated with poor prognosis (P < .001). Among these targets, expression of SDC3 was directly controlled by miR-144-5p, and its expression enhanced cancer cell aggressiveness. We identified genes downstream by SDC3 regulation. Data showed that expression of 10 of the downstream genes (IL18RAP, SDC3, SH2D1A, GZMH, KIF21B, TMC8, GAB3, HLA-DPB2, PLEK, and C1QB) significantly predicted poor prognosis of the patients (P = .0064). These data indicated that the antitumor miR-144-5p/oncogenic SDC3 axis was deeply involved in RCC pathogenesis. Clustered miRNAs (miR-451a, miR-144-5p, and miR-144-3p) acted as antitumor miRNAs, and their targets were intimately involved in RCC pathogenesis.

Tumor suppressor miR-449a inhibits the development of gastric cancer via down-regulation of SGPL1

MicroRNAs (miRNAs) are small noncoding RNAs that are known to participate in the regulation of many physiological and pathological processes, which can indirectly influence the development of malignant behaviors. Numerous studies have demonstrated that miR-449a plays important roles in human carcinogenesis. However, its precise functional and regulatory roles remain unclear. In this study, we mainly explored the functional role of miR-449a in gastric cancer (GC). The expression levels of miR-449a in 98 cases of GC tissues and cell lines were determined by qRT-PCR. The possible mechanisms of miR-449a in GC cells were explored by fluorescence reporter assay. miR-449a expression was significantly lower in GC tissues compared to matched para-carcinoma tissues and was associated with tumor differentiation. Furthermore, in vitro knockdown of miR-449a by siRNA significantly inhibited MKN-28 cell proliferation, migration and invasion as well as tumorigenesis via inducing G0/G1 arrest of GC cells. In addition, we identified SGPL1 as a target of miR-449a and demonstrated that miR-449a regulated SGPL1 expression via binding its 3′-UTR region. The experiments indicated that miR-449a functions as a novel tumor suppressor in GC and its anti-oncogenic activity may involve its inhibition of the target gene SGPL1. These findings suggested that miR-449a may be a promising candidate for the development of antitumor drugs targeting GC.

MicroRNAs (miRNAs) are small noncoding RNAs that are known to participate in the regulation of many physiological and pathological processes, which can indirectly influence the development of malignant behaviors.

Effects of microRNA-24 targeting C-myc on apoptosis, proliferation, and cytokine expressions in chondrocytes of rats with osteoarthritis via MAPK signaling pathway

To investigate whether microRNA-24 (miR-24) targeting C-myc affects chondrocytes of rats with osteoarthritis (OA) via the MAPK signaling pathway. Thirty rats were assigned as a sham group and an OA group (established as OA rat models by cutting the anterior cruciate ligaments and removing 1/3 medial meniscus). TUNEL staining and immunohistochemistry were conducted for cell apoptosis index (AI) and positive expression rate of C-myc protein. Enzyme-linked immuno sorbent assay (ELISA) was carried out for serum level of IL-1β and TNF-α. Primary chondrocytes were assigned into the blank, negative control (NC), miR-24 mimics, miR-24 inhibitors, siRNA-C-myc, and miR-24 inhibitors+siRNA-C-myc groups. The expressions of miR-24, C-myc, p38, ERK, JNK, IL-1β, and TNF-α in tissues and cells were detected using reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) and Western blotting. CCK8 assay and flow cytometry were performed for cell proliferation and apoptosis. The OA group showed higher IL-1β, TNF-α, AI, and C-myc than the sham group. C-myc is a target gene of miR-24. Compared with the blank group, the miR-24 mimics and siRNA-C-myc groups showed reduced expression of C-myc, IL-1β, TNF-α, p38, p-p38, ERK, p-ERK, JNK, and p-JNK, apoptosis rate yet increased cell proliferation; however, the miR-24 inhibitors group exhibited an opposite trend. The miR-24 inhibitors+siRNA-C-myc group presented a same tendency compared to the siRNA-C-myc group. Upregulated miR-24 downregulates C-myc could suppress apoptosis and promote proliferation of chondrocytes to prevent the occurrence and subsequent progression of OA via inactivating the MAPK signaling pathway.

MicroRNA-23a/27a/24-2 cluster promotes gastric cancer cell proliferation synergistically

Previous studies have indicated that certain microRNAs (miRNAs/miRs) function as either tumor suppressors or oncogenes in human cancer. The present study identified the miR-23a/27a/24-2 cluster, containing miR-23, miR-27a and miR-24, as an oncogene in gastric cancer. The expression of the miR-23a/27a/24-2 cluster was upregulated in clinical gastric cancer tissues. Transfection with inhibitors of miR-23a, miR-27a, or miR-24, either independently or together, repressed in vitro colony formation and in vivo tumor formation. The miR23a/27a/24-2 cluster inhibitors repressed the growth of gastric cancer cells in a synergistic manner. In addition, treatment with lower doses of the miRNA inhibitor mixture induced the formation of apoptotic bodies. According to computational predictions using TargetScan, suppressor of cytokine-induced signaling 6 (SOCS6) was identified as one of the downstream target genes of the miR-23a/27a/24-2 cluster. The expression of SOCS6 was significantly lower in tumor tissues than in matched normal tissues (P<0.01) and was associated with poor survival (P<0.00001). Taken together, these results strongly suggested that the miR-23a/27a/24-2 cluster may mediate the progression of gastric cancer through the suppression of SOCS6 expression. The present study also provides a novel molecular target for the development of an anti-gastric cancer agent.

Gastrin inhibits gastric cancer progression through activating the ERK-P65-miR23a/27a/24 axis

BACKGROUND

To test the hypothesis that activated extracellular signal-regulated kinase (ERK) regulates P65-miR23a/27a/24 axis in gastric cancer (GC) and the ERK-P65-miR23a/27a/24 axis plays an important role in the development of GC, and to evaluate the role of gastrin in GC progression and ERK-P65-miR23a/27a/24 axis.

METHODS

The component levels of the ERK-P65-miR23a/27a/24 axis in four fresh GC tissues, 101 paraffin-embedded GC tissues and four GC cell lines were determined by Western blotting, immunohistochemistry (IHC) or qRT-PCR. The effects of gastrin on GC were first evaluated by measuring gastrin serum levels in 30 healthy and 70 GC patients and performing a correlation analysis between gastrin levels and survival time in 27 GC patients after eight years of follow-up, then evaluated on GC cell lines, GC cell xenograft models, and patient-derived xenografts (PDX) mouse models. The roles of ERK-P65-miR23a/27a/24 axis in GC progression and in the effects of gastrin on GC were examined.

RESULTS

ERK- P65-miR23a/27a/24 axis was proved to be present in GC cells. The levels of components of ERK-P65-miR23a/27a/24 axis were decreased in GC tissue samples and PGC cells. The decreased levels of components of ERK-P65-miR23a/27a/24 axis were associated with poor prognosis of GC, and ERK-P65-miR23a/27a/24 axis played a suppressive role in GC progression. Low blood gastrin was correlated with poor prognosis of the GC patients and decreased expression of p-ERK and p-P65 in GC tissues. Gastrin inhibited proliferation of poorly-differentiated GC (PGC) cells through activating the ERK-P65-miR23a/27a/24 axis. Gastrin inhibited GC growth and enhanced the suppression of GC by cisplatin in mice or PGC cell culture models through activating the ERK-P65-miR23a/27a/24 axis or its components.

CONCLUSIONS

ERK-P65-miR23a/27a/24 axis is down-regulated, leading to excess GC growth and poor prognosis of GC. Low gastrin promoted excess GC growth and contributed to the poor prognosis of the GC patients by down-regulating ERK-P65-miR23a/27a/24 axis. Gastrin inhibits gastric cancer growth through activating the ERK-P65-miR23a/27a/24 axis.

MiR-23a transcriptional activated by Runx2 increases metastatic potential of mouse hepatoma cell via directly targeting Mgat3

MicroRNAs (miRNAs) and aberrant glycosylation both play important roles in tumor metastasis. In this study, the role of miR-23a in N-glycosylation and the metastasis of mouse hepatocellular carcinoma (HCC) cells was investigated. The miRNA expression array profiles that were confirmed by qPCR and Western blot analyses revealed higher miR-23a expression levels in Hca-P cells (with lymphatic metastasis potential) than in Hepa1-6 cells (with no lymphatic metastasis potential), while the expression of mannoside acetylglucosaminyltransferase 3 (Mgat3) was negatively associated with metastasis potential. Mgat3 is a key glycosyltransferase in the synthesis of the bisecting (β1,4GlcNAc branching) N-glycan structure. Bioinformatics analysis indicated that Mgat3 may be a target of miR-23a, and this hypothesis was verified by dual-luciferase reporter gene assays. Furthermore, we found that the transcription factor Runx2 can directly bind to the miR-23a gene promoter and promote its expression, as shown in dual-luciferase reporter gene assays and ChIP assays. Collectively, these results indicate that miR-23a might increase the metastatic potential of mouse HCC by affecting the branch formation of N-glycan chains presented on the cell surface through the targeting of the glycosyltransferase Mgat3. These findings may provide insight into the relationship between abnormal miRNA expression and aberrant glycosylation during tumor lymphatic metastasis.

Expression and clinical significance of miR-23a and MTSS1 in diffuse large B-cell lymphoma

The present study investigated the expression and clinical significance of micro-ribonucleic acid-23a (miR-23a) and metastasis suppressor 1 (MTSS1) in diffuse large B-cell lymphoma (DLBCL). A total of 70 cases of tumor tissues of patients with DLBCL and 30 cases of reactive lymphoid hyperplasia tissues were collected. OCI-LY10 cell was transfected with miR-23a antisense oligonucleotide (miR-23a ASO). The expression of miR-23a and MTSS1 in tumor tissues of patients with DLBCL and reactive lymphoid hyperplasia tissues were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry. Spearmans test was used for correlation analysis was also performed for their expression. The relationship of the expressions of miR-23a and MTSS1 with the pathological parameters of patients with DLBCL was further analyzed. The DLBCL OCI-LY10 cells were cultured in vitro, and gene silencing downregulated the expression of miR-23a in OCI-LY10 cells. The expression of miR-23a was studied via RT-qPCR, and the effect of downregulation of miR-23a on MTSS1 protein expression was determined by western blot analysis. Moreover, the effects of miR-23a on the proliferation, metastasis and invasion capacities of OCI-LY10 cells were observed by both methyl thiazolyl tetrazolium (MTT) assay and Transwell chamber assay. The results of RT-qPCR showed that the mRNA expression of miR-23a in DLBCL tissues was significantly higher than that of reactive hyperplasia tissues. Immunohistochemical results revealed that the positive expression rate of MTSS1 in DLBCL tissues (30.00%) was significantly lower in comparison to reactive hyperplasia tissues (90.00%). Correlation analysis revealed that the miR-23a expression had a significant negative correlation with MTSS1 expression (r=-0.538, p=0.01). The expression of miR-23a and MTSS1 were correlated with the Ann Arbor staging, extranodal invasion and International Prognostic Index (IPI) scores of patients (p<0.05). However, they had no significant correlation with the sex and age of patients (p>0.05). After the downregulation of miR-23a expression, the MTSS1 protein expression in OCI-LY10 cells showed a significant increase. However, the proliferation, metastasis and invasion capacities of OCI-LY10 cells were obviously decreased. In conclusion, miR-23a promoted the proliferation, invasion and metastasis of DLBCL OCI-LY10 cells through the targeted inhibition of MTSS1. The high expression of miR-23a and the low expression of MTSS1 protein could be used as reference indexes for the prognosis of DLBCL.

An integrated view of the role of miR-130b/301b miRNA cluster in prostate cancer

Prostate cancer is a major health problem worldwide due to its high incidence morbidity and mortality. There is currently a need of improved biomarkers, capable to distinguish mild versus aggressive forms of the disease, and thus guide therapeutic decisions. Although miRNAs deregulated in cancer represent exciting candidates as biomarkers, its scientific literature is frequently fragmented in dispersed studies. This problem is aggravated for miRNAs belonging to miRNA gene clusters with shared target genes. The miRNA cluster composed by hsa-mir-130b and hsa-mir-301b precursors was recently involved in prostate cancer pathogenesis, yet different studies assigned it opposite effects on the disease. We sought to elucidate the role of the human miR-130b/301b miRNA cluster in prostate cancer through a comprehensive data analysis of most published clinical cohorts. We interrogated methylomes, transcriptomes and patient clinical data, unifying previous reports and adding original analysis using the largest available cohort (TCGA-PRAD). We found that hsa-miR-130b-3p and hsa-miR-301b-3p are upregulated in neoplastic vs normal prostate tissue, as well as in metastatic vs primary sites. However, this increase in expression is not due to a decrease of the global DNA methylation of the genes in prostate tissues, as the promoter of the gene remains lowly methylated in normal and neoplastic tissue. A comparison of the levels of human miR-130b/301b and all the clinical variables reported for the major available cohorts, yielded positive correlations with malignance, specifically significant for T-stage, residual tumor status and primary therapy outcome. The assessment of the correlations between the hsa-miR-130b-3p and hsa-miR-301b-3p and candidate target genes in clinical samples, supports their repression of tumor suppressor genes in prostate cancer. Altogether, these results favor an oncogenic role of miR-130b/301b cluster in prostate cancer.

Plasma microRNA profiles: identification of miR-23a as a novel biomarker for chemoresistance in esophageal squamous cell carcinoma

BACKGROUND

This study aims to explore novel microRNAs in plasma for predicting chemoresistance in preoperative chemotherapy of patients with esophageal squamous cell carcinoma (ESCC) using a microRNA array-based approach.

RESULTS

(1) Four candidate microRNAs (miR-223, 103a, 23b and 23a), which were highly expressed in the pretreatment plasma of patients with a low histopathologic response, were selected. (2) In a large-scale validation analysis by quantitative RT–PCR, plasma levels of miR-223, miR-23b and miR-23a were significantly higher in patients with a low histopathologic response than in those with a high histopathologic response (p = 0.0345, p = 0.0125 and p = 0.0114). (3) Of all candidate microRNAs, miR-23a expression of pretreatment ESCC tumor tissues was significantly higher in ESCC patients with a low histopathologic response than in those with a high histopathologic response (p = 0.0278). (4) After overexpressing each candidate in ESCC cells, miR-23a induced significant chemoresistance to both 5-fluorouracil and cisplatin, and miR-223 to cisplatin in vitro. (5) A high level of plasma miR-23a, which tended to correlate with lymphatic invasion (p = 0.0808) and deep depth of invasion (p = 0.0658), was an independent risk factor for chemoresistance in ESCC (p = 0.0222; odds ratio: 12.4; range 1.46–105).

MATERIALS AND METHODS

We used the Toray^® 3D-Gene microRNA array-based approach to compare plasma microRNA levels between patients with a high or a low histopathologic response to chemotherapy. All patients underwent a preoperative chemotherapy regimen with cisplatin plus 5-fluorouracil.

CONCLUSIONS

Plasma miR-23a might be a useful biomarker for predicting chemoresistance in ESCC patients.

miR‑152 regulates TGF‑β1‑induced epithelial‑mesenchymal transition by targeting HPIP in tubular epithelial cells

Renal fibrosis is a common pathological feature of chronic kidney diseases, and their development and progression are influenced by epigenetic modifications including aberrant microRNA (miRNA or miR) expression. miRNAs have been demonstrated to modulate the aggressiveness of various cancers and have emerged as possible therapeutic agents for the management of renal fibrosis. Transforming growth factor β1 (TGF‑β1)‑induced epithelial‑mesenchymal transition (EMT) of tubular epithelial cells serves a role in the initiation and progression of renal fibrosis. Furthermore, recent results indicated that the progression of EMT is reversible. The present study aimed to clarify the role of miR‑152 in EMT of the tubular epithelial cell line HK‑2, stimulated by TGF‑β1, using in vitro transfection with a miR‑152 mimic and to further investigate the underlying mechanism of miR‑152 activity. In the present study, miR‑152 expression was significantly reduced in TGF‑β1‑treated HK‑2 cells, accompanied by an increased expression of hematopoietic pre‑B‑cell leukemia transcription factor (PBX)‑interacting protein (HPIP). Additionally, miR‑152 overexpression inhibited TGF‑β1‑induced EMT and suppressed HPIP expression by directly targeting the 3' untranslated region of HPIP in HK‑2 cells. Furthermore, upregulation of HPIP reversed miR‑152‑mediated inhibitory effects on the EMT. Collectively, the results suggest that downregulation of miR‑152 initiates the dedifferentiation of renal tubules and progression of renal fibrosis, which may provide important targets for prevention strategies of renal fibrosis.

Altered microRNA expression profile in the peripheral lymphoid compartment of multiple myeloma patients with bisphosphonate-induced osteonecrosis of the jaw

Bisphosphonates are formidable inhibitors of osteoclast-mediated bone resorption employed for therapy of multiple myeloma (MM) subjects with osteolytic lesions. Osteonecrosis of the jaw (ONJ) is an uncommon drug-induced adverse event of these agents. MicroRNAs (miRNAs) are a group of small, noncoding RNAs nucleotides, which are essential post-transcriptional controllers of gene expression. They have a central role in the normal bone development. The goal of our study was to investigate 18 miRNAs, whose targets were previously validated and described in MM subjects without ONJ, in peripheral lymphocytes of MM subjects with bisphosphonate-induced ONJ. Utilizing reverse transcription quantitative polymerase chain reaction, we evaluated miRNAs in five healthy subjects and in five MM patients with ONJ. Our experimental data revealed that a diverse miRNA signature for ONJ subjects emerged with respect to control subjects. Using the filter for in silico analysis, among the 18 miRNAs, we recognized 14 dysregulated miRNAs. All these miRNAs were significantly over-expressed in patients vs controls (MIR-16-1, MIR-21, MIR-23A, MIR-28, MIR-101-1, MIR-124-1, MIR-129, MIR-139, MIR-145, MIR-149, MIR-202, MIR-221, MIR-424, MIR-520). Among them, six were strongly upregulated (fourfold upregulated and more). These miRNAs target numerous pathways and genes implicated in calcium ion binding, bone resorption, mineralization of bone matrix, and differentiation and maintenance of bone tissue. A modified microRNA expression profile after zoledronate therapy could participate to the onset of ONJ. Targeting these miRNAs could provide a new opportunity for the prevention or treatment of ONJ.

ER stress mediated regulation of miR23a confer Hela cells better adaptability to utilize glycolytic pathway

Cancer cells exhibit increased dependency on aerobic glycolysis, a phenomenon referred as the "Warburg effect" and therefore, blocking glycolysis by using non-metabolizable analogues of glucose, like 2-Deoxy glucose (2-DG), has been proposed to be of huge therapeutic importance. One of the major drawbacks of using 2-DG as a chemotherapeutic agent is that it can induce ER stress. ER stress is a hall mark in many solid tumors and the unfolded protein response (UPR) associated with it initiates many survival mechanisms in cancer cells. In the present study, we report a novel survival mechanism associated with ER stress, by which the cancer cells become more adapted to aerobic glycolysis. When ER stress was induced in Hela cells by treating them with 2-DG or Thapsigargin (TG) the expression and activity of LDH was significantly up regulated, conferring the cells a greater glycolytic potential. A simultaneous decrease was observed in the expression of miR-23a, which was predicted in silico to have target site on the 3'UTR of LDH A and B mRNAs. miRNA over expression studies and mRNA degradation assays suggest that miR-23a could target LDH A and LDH B mRNAs. Further on the basis of our results and previous scientific reports, we propose that "c-Myc," which is over expressed during ER stress, repress the expression of miR-23a, which in turn regulates the expression of its target genes viz., LDH A and LDH B, thereby making the cells more competent to survive in tumor microenvironment, which requires efficient use of aerobic glycolysis.

DDX5/p68 associated lncRNA LOC284454 is differentially expressed in human cancers and modulates gene expression

Long non-coding RNAs (lncRNAs) are emerging as important players in regulation of gene expression in higher eukaryotes. DDX5/p68 RNA helicase protein which is involved in splicing of precursor mRNAs also interacts with lncRNAs like, SRA and mrhl, to modulate gene expression. We performed RIP-seq analysis in HEK293T cells to identify the complete repertoire of DDX5/p68 interacting transcripts including 73 single exonic (SE) lncRNAs. The LOC284454 lncRNA is the second top hit of the list of SE lncRNAs which we have characterized in detail for its molecular features and cellular functions. The RNA is located in the same primary transcript harboring miR-23a∼27a∼24-2 cluster. LOC284454 is a stable, nuclear restricted and chromatin associated lncRNA. The sequence is conserved only in primates among 26 different species and is expressed in multiple human tissues. Expression of LOC284454 is significantly reduced in breast, prostate, uterus and kidney cancer and also in breast cancer cell lines (MCF7 and T47D). Global gene expression studies upon loss and gain of function of LOC284454 revealed perturbation of genes related to cancer-related pathways. Focal adhesion and cell migration pathway genes are downregulated under overexpression condition, and these genes are significantly upregulated in breast cancer cell lines as well as breast cancer tissue samples suggesting a functional role of LOC284454 lncRNA in breast cancer pathobiology.

Multitargeting activity of miR-24 inhibits long-term melatonin anticancer effects

We have previously shown that melatonin exerts tumor suppressor activities by inducing the p38-p53 axis. This occurred within a few hours while no data are available on how melatonin pathway can be sustained on the long term. Here we show that miR-24, which has been demonstrated to target genes involved in the DNA repair process, targets p38, p53, PML and H2AX simultaneously. We show that long-term treatment with melatonin can decrease miR-24 levels post-transcriptionally, which pairs with a long-wave regulation of genes involved in cell proliferation, DNA damage, RNA metabolism and cell shape and transformation. Moreover, we show that melatonin can inhibit cell proliferation and migration, at least in part, by downregulating miR-24. Furthermore, we propose the involvement of hnRNP A1, which is downregulated by melatonin and involved in miRNA processing, in the regulation of miR-24 levels by melatonin. We conclude showing that miR-24 is upregulated in colon, breast and head and neck datasets and its levels negatively correlate with overall survival.

The microRNA regulatory landscape of MSC-derived exosomes: a systems view

Mesenchymal stem cell (MSC)-derived exosomes mediate tissue regeneration in a variety of diseases including ischemic heart injury, liver fibrosis, and cerebrovascular disease. Despite an increasing number of studies reporting the therapeutic effects of MSC exosomes, the underlying molecular mechanisms and their miRNA complement are poorly characterized. Here we microRNA (miRNA)-profiled MSC exosomes and conducted a network analysis to identify the dominant biological processes and pathways modulated by exosomal miRNAs. At a system level, miRNA-targeted genes were enriched for (cardio)vascular and angiogenesis processes in line with observed cardiovascular regenerative effects. Targeted pathways were related to Wnt signaling, pro-fibrotic signaling via TGF-β and PDGF, proliferation, and apoptosis. When tested, MSC exosomes reduced collagen production by cardiac fibroblasts, protected cardiomyocytes from apoptosis, and increased angiogenesis in HUVECs. The intrinsic beneficial effects were further improved by virus-free enrichment of MSC exosomes with network-informed regenerative miRNAs capable of promoting angiogenesis and cardiomyocyte proliferation. The data presented here help define the miRNA landscape of MSC exosomes, establish their biological functions through network analyses at a system level, and provide a platform for modulating the overall phenotypic effects of exosomes.

Horizontal transfer of miR-23a from hypoxic tumor cell colonies can induce angiogenesis

Neo vessel formation by angiogenesis is an important event during many pathological conditions including cancer, where it is indispensable for tumor growth and survival. Although, various pro-angiogenic cytokines and soluble factors, secreted by tumor cells, have been reported to promote angiogenesis, recent studies have shown regulatory role of exosomes, secreted by tumor cells in the process of angiogenesis. These exosomes are capable of carrying nucleic acids, proteins, etc., as their cargo. Under the light of these facts and considering the presence of miRNAs, the non-coding RNAs capable of regulating target gene expression, as one of the major cargos in the exosomes, we investigated, whether exosomes derived from normoxic and hypoxic tumor cell colonies exhibit difference in levels of miR-23∼27∼24 cluster members and if so, to check the significance of their horizontal transfer on the process of angiogenesis. Results of our study showed that exosomes secreted by hypoxic tumor cell colonies possess significantly higher levels of miR23a and can induce angiogenesis. Further, we have shown that exosomes secreted by cells that ectopically over express miR23a is capable of inducing angiogenesis in different angiogenic model systems such as CAM, in ovo Xenograft and HUVEC models systems. Further, mechanistic analysis revealed that miR23a driven regulation of angiogenesis is brought about by down regulation of SIRT1 in the recipient cells. Collectively, the results presented here suggest that exosomal transfer of miR23a from tumor cell colonies can induce the process of angiogenesis by targeting SIRT1 in the recipient endothelial cells.

The Oncogenic Role of Tribbles 1 in Hepatocellular Carcinoma Is Mediated by a Feedback Loop Involving microRNA-23a and p53

Hepatocellular carcinoma (HCC) is a common malignancy associated with a high risk of recurrence and metastasis and a poor prognosis. Here, we examined the involvement of the pseudokinase Tribbles 1 (TRIB1), a scaffold protein associated with several malignancies, in HCC and investigated the underlying mechanisms. TRIB1 was upregulated in HCC tissues and cell lines in correlation with low levels of p53. TRIB1 gain and loss of function experiments indicated that TRIB1 promoted HCC cell viability concomitant with the downregulation of p53, and induced HCC cell migration, invasion, and epithelial-mesenchymal transition. TRIB1 was identified as a target of microRNA-23a (miR-23a), and miR-23a overexpression downregulated TRIB1 and upregulated p53 in HCC cells. Ectopic expression of TRIB1 upregulated β-catenin and its effectors c-myc and MMP-7 in a p53-dependent manner. TRIB1 silencing inhibited tumor growth and promoted apoptosis in vivo via a mechanism that would involve the modulation of p53 and β-catenin signaling. The present results indicate that TRIB1 promotes HCC tumorigenesis and invasiveness via a feedback loop that involves the modulation of its expression by miR-23a with the likely downregulation of p53, and suggest the involvement of the β-catenin signaling pathway. These findings suggest potential targets for the treatment of HCC and therefore merit further investigation.

MiR-24 induces chemotherapy resistance and hypoxic advantage in breast cancer

Breast cancer remains one of the leading causes of cancer mortality among women. It has been proved that the onset of cancer depends on a very small pool of tumor cells with a phenotype similar to that of normal adult stem cells. Cancer stem cells (CSC) possess self-renewal and multilineage differentiation potential as well as a robust ability to sustain tumorigenesis. Evidence suggests that CSCs contribute to chemotherapy resistance and to survival under hypoxic conditions. Interestingly, hypoxia in turn regulates self-renewal in CSCs and these effects may be primarily mediated by hypoxic inducible factors (HIFs). Recently, microRNAs (miRNAs) have emerged as critical players in the maintenance of pluripotency and self-renewal in normal and cancer stem cells. Here, we demonstrate that miR-24 is upregulated in breast CSCs and that its overexpression increases the number of mammospheres and the expression of stem cell markers. MiR-24 also induces apoptosis resistance through the regulation of BimL expression. Moreover, we identify a new miR-24 target, FIH1, which promotes HIFα degradation: miR-24 increases under hypoxic conditions, causing downregulation of FIH1 and upregulation of HIF1α. In conclusion, miR-24 hampers chemotherapy-induced apoptosis in breast CSCs and increases cell resistance to hypoxic conditions through an FIH1−HIFα pathway.

Expression, regulation and mechanism of action of the miR-17-92 cluster in tumor cells (Review)

MicroRNAs (miRNAs), a class of short, single-stranded non-coding RNAs, regulate and control gene expression in eukaryotes by degrading mRNA at the post-transcriptional level. Regulation by miRNAs involves a plethora of biological processes, such as cell differentiation, proliferation, metastasis, metabolism, apoptosis, tumorigenesis and others. miRNAs also represent a powerful tool in disease diagnosis and prognosis. The miR-17-92 cluster, one of the most extensively investigated microRNA clusters, comprises six mature miRNA members, including miR-17, miR-18a, miR-19a, miR-19b, miR-20a and miR-92a. Originally identified as being involved in tumorigenesis, it is currently evident that the expression of the miR-17-92 cluster is upregulated in a wide range of tumor cells and cancer types; thus, this cluster has been identified as a potential oncogene. Considering the growing interest in the field of miR-17-92 research, we herein review recent advances in the expression and regulation of this cluster in various cancer cells, discuss the proposed mechanism of action for tumorigenesis and tumor development, and propose clinical and therapeutic applications for miR-17-92 cluster members, such as potential cancer biomarkers.

Regulation of TGF-β-mediated endothelial-mesenchymal transition by microRNA-27

Multiple microRNAs (miRNAs) regulate epithelial-mesenchymal transition and endothelial-mesenchymal transition (EndMT). Here we report that microRNA-27b (miR-27b) positively regulates transforming growth factor-β (TGF-β)-induced EndMT of MS-1 mouse pancreatic microvascular endothelial cells. TGF-β induced miR-23b/24-1/27b expression, and inhibition of miR-27 suppressed TGF-β-mediated induction of mesenchymal genes. Genome-wide miRNA target analysis revealed that miR-27 targets Elk1, which acts as a competitive inhibitor of myocardin-related transcription factor-serum response factor signalling and as a myogenic repressor. miR-27b was also found to regulate several semaphorin receptors including Neuropilin 2, Plexin A2 and Plexin D1. These results suggest important roles of miR-27 in TGF-β-driven EndMT.

RNA-seq reveals distinctive RNA profiles of small extracellular vesicles from different human liver cancer cell lines

Liver cancer (LC) is one of the most common cancers and represents the third highest cause of cancer-related deaths worldwide. Extracellular vesicle (EVs) cargoes, which are selectively enriched in RNA, offer great promise for the diagnosis, prognosis and treatment of LC. Our study analyzed the RNA cargoes of EVs derived from 4 liver-cancer cell lines: HuH7, Hep3B, HepG2 (hepato-cellular carcinoma) and HuH6 (hepatoblastoma), generating two different sets of sequencing libraries for each. One library was size-selected for small RNAs and the other targeted the whole transcriptome. Here are reported genome wide data of the expression level of coding and non-coding transcripts, microRNAs, isomiRs and snoRNAs providing the first comprehensive overview of the extracellular-vesicle RNA cargo released from LC cell lines. The EV-RNA expression profiles of the four liver cancer cell lines share a similar background, but cell-specific features clearly emerge showing the marked heterogeneity of the EV-cargo among the individual cell lines, evident both for the coding and non-coding RNA species.

Global mapping of miRNA-target interactions in cattle (Bos taurus)

With roles in development, cell proliferation and disease, micro-RNA (miRNA) biology is of great importance and a potential therapeutic target. Here we used cross-linking immunoprecipitation (CLIP) and ligation of miRNA-target chimeras on the Argonaute (AGO) protein to globally map miRNA interactions in the cow. The interactome is the deepest reported to date. miRNA targeting principles are consistent with observations in other species, but with expanded pairing rules. Experimental mapping robustly predicted functional miR-17 regulatory sites. From miRNA-specific targeting for >5000 mRNAs we determined gene ontologies (GO). This confirmed repression of genes important for embryonic development and cell cycle progress by the let-7 family, and repression of those involved in cell cycle arrest by the miR-17 family, but also suggested a number of unappreciated miRNA functions. Our results provide a significant resource for understanding of bovine and species-conserved miRNA regulation, and demonstrate the power of experimental methods for establishing comprehensive interaction maps.

MiR-23-TrxR1 as a novel molecular axis in skeletal muscle differentiation

Thioredoxin reductase 1 (TrxR1) is a selenocysteine-containing protein involved in cellular redox homeostasis which is downregulated in skeletal muscle differentiation. Here we show that TrxR1 decrease occurring during myogenesis is functionally involved in the coordination of this cellular process. Indeed, TrxR1 depletion reduces myoblasts growth by inducing an early myogenesis -related gene expression pattern which includes myogenin and Myf5 up-regulation and Cyclin D1 decrease. On the contrary, the overexpression of TrxR1 during differentiation delays myogenic process, by negatively affecting the expression of Myogenin and MyHC. Moreover, we found that miR-23a and miR-23b - whose expression was increased in the early stage of C2C12 differentiation - are involved in the regulation of TrxR1 expression through their direct binding to the 3' UTR of TrxR1 mRNA. Interestingly, the forced inhibition of miR-23a and miR-23b during C2C12 differentiation partially rescues TrxR1 levels and delays the expression of myogenic markers, suggesting the involvement of miR-23 in myogenesis via TrxR1 repression. Taken together, our results depict for the first time a novel molecular axis, which functionally acts in skeletal muscle differentiation through the modulation of TrxR1 by miR-23.

TGF-β1 Downregulates the Expression of CX3CR1 by Inducing miR-27a-5p in Primary Human NK Cells

Activity of human natural killer (NK) cells against cancer cells is deeply suppressed by TGF-β1, an immunomodulatory cytokine that is released and activated in the tumor microenvironment. Moreover, our previous data showed that TGF-β1 modifies the chemokine receptor repertoire of NK cells. In particular, it decreases the expression of CX₃CR1 that drives these effectors toward peripheral tissues, including tumor sites. To identify possible mechanisms mediating chemokine receptors modulation, we analyzed the microRNA profile of TGF-β1-treated primary NK cells. The analysis pointed out miR-27a-5p as a possible modulator of CX₃CR1. We demonstrated the functional interaction of miR-27a-5p with the 3′ untranslated region (3′UTR) of CX₃CR1 mRNA by two different experimental approaches: by the use of a luciferase assay based on a reporter construct containing the CX₃CR1 3′UTR and by transfection of primary NK cells with a miR-27a-5p inhibitor. We also showed that the TGF-β1-mediated increase of miR-27a-5p expression is a consequence of miR-23a-27a-24-2 cluster induction. Moreover, we demonstrated that miR-27a-5p downregulates the surface expression of CX₃CR1. Finally, we showed that neuroblastoma cells induced in resting NK cells a downregulation of the CX₃CR1 expression that was paralleled by a significant increase of miR-27a-5p expression. Therefore, the present study highlights miR-27a-5p as a pivotal TGF-β1-induced regulator of CX₃CR1 expression.

A three-microRNA signature identifies two subtypes of glioblastoma patients with different clinical outcomes

Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumor in adults, characterized by aggressive growth, limited response to therapy, and inexorable recurrence. Because of the extremely unfavorable prognosis of GBM, it is important to develop more effective diagnostic and therapeutic strategies based on biologically and clinically relevant patient stratification systems. Analyzing a collection of patient‐derived GBM stem‐like cells (GSCs) by gene expression profiling, nuclear magnetic resonance spectroscopy, and signal transduction pathway activation, we identified two GSC clusters characterized by different clinical features. Due to the widely documented role played by microRNAs (miRNAs) in the tumorigenesis process, in this study we explored whether these two GBM patient subtypes could also be discriminated by different miRNA signatures. Global miRNA expression pattern was analyzed by oblique principal component analysis and principal component analysis. By a combined inferential strategy on PCA results, we identified a reduced set of three miRNAs – miR‐23a, miR‐27a, and miR‐9* (miR‐9‐3p) – able to discriminate the proneural‐ and mesenchymal‐like GSC phenotypes as well as mesenchymal and proneural subtypes of primary GBM included in The Cancer Genome Atlas (TCGA) data set. Kaplan–Meier analysis showed a significant correlation between the selected miRNAs and overall survival in 429 GBM specimens from TCGA‐identifying patients who had an unfavorable outcome. The survival prognostic capability of the three‐miRNA signatures could have important implications for the understanding of the biology of GBM subtypes and could be useful in patient stratification to facilitate interpretation of results from clinical trials.

The Central Conserved Region (CCR) of Respiratory Syncytial Virus (RSV) G Protein Modulates Host miRNA Expression and Alters the Cellular Response to Infection

Respiratory Syncytial Virus (RSV) infects respiratory epithelial cells and deregulates host gene expression by many mechanisms including expression of RSV G protein (RSV G). RSV G protein encodes a central conserved region (CCR) containing a CX3C motif that functions as a fractalkine mimic. Disruption of the CX3C motif (a.a. 182-186) located in the CCR of the G protein has been shown to affect G protein function in vitro and the severity of RSV disease pathogenesis in vivo. We show that infection of polarized Calu3 respiratory cells with recombinant RSV having point mutations in Cys173 and 176 (C173/176S) (rA2-GC12), or Cys186 (C186S) (rA2-GC4) is associated with a decline in the integrity of polarized Calu-3 cultures and decreased virus production. This is accompanied with downregulation of miRNAs let-7f and miR-24 and upregulation of interferon lambda (IFNλ), a primary antiviral cytokine for RSV in rA2-GC12/rA2-GC4 infected cells. These results suggest that residues in the cysteine noose region of RSV G protein can modulate IFN λ expression accompanied by downregulation of miRNAs, and are important for RSV G protein function and targeting.

Role of microRNAs in premature ovarian insufficiency

Premature ovarian insufficiency (POI) is a typical disorder of amenorrhea lasting for a minimum of 4 months. The typical characteristics comprised of declined estrogen and raised serum concentrations of follicle-stimulating hormone (FSH) in women <40-year-old, primarily originating from iatrogenic factors, karyotypic abnormalities, and genetic factors. However, the etiology of POI remains unknown in approximately 90% of cases. POI could lead to infertility, osteoporosis, cardiovascular disorder, and cognitive dysfunction. MicroRNAs (miRNAs) are a class of endogenous noncoding RNAs (ncRNAs) that can mediate post-translational silencing of the genes involved in the regulation of proliferation, differentiation, apoptosis, development, tumorigenesis, and hematopoiesis. Recently, the regulatory functions of miRNAs in the development of POI have been the topic of intensive research. The present review addresses the association of miRNAs' machinery genes (Dicer, Drosha, and XPO5) with POI and the miRNA expression profiles in the plasma of patients with POI. In addition, several specific miRNAs (miR-23a, miR-27a, miR-22-3p, miR-146a, miR-196a, miR-290-295, miR-423, and miR-608) related to POI are also examined in order to highlight the issues that deserve further investigation. A thorough understanding of the exact regulatory roles of miRNAs is imperative to gain novel insights into the etiology of idiopathic POI and offer new research directions in the field.

Comparison of microRNA profiles between benign and malignant salivary gland tumors in tissue, blood and saliva samples: a prospective, case-control study

Introduction

Salivary gland tumors (SGTs) are rare head and neck malignancies consisting of a spectrum of tumors with different biological behaviors.

Objective

In this study we aimed to find out differential expression of microRNA profiles between benign and malignant SGTs.

Methods

We investigated the possible role of 95 microRNAs in the 20 patients with salivary gland tumors with comparison of 17 patients without malignancy or salivary gland diseases. Sixteen of the tumors were benign (seven pleomorphic adenomas, nine Warthin tumors), four of them were malignant (two squamous cell carcinomas, one high grade mucoepidermoid carcinoma, one adenocarcinoma). Serum and saliva samples were collected from both patients and control group. Tissue samples of tumor masses were also collected from patient group.

Results

Among studied microRNAs miR-21, miR-23a, miR-27a, miR-223, miR-125b, miR-126, miR-146a, miR-30e were down regulated in the benign group compared to control group in the serum samples (p-values are 0.04, 0.00005, 0.00005, 0.0022, 0.031, 0.00008, 0.044, and 0.0007, respectively). When tissue samples were studied miR-21, miR-31, miR-199a-5p, miR-146b, miR-345 were up-regulated in the malignant group compared to benign group (p values are 0.006, 0.02, 0.013, 0.013, 0.041, respectively). miR-30e showed statistically significant up-regulation in malignant tumor group's plasma samples compared to benign group (p = 0.034). There was no statistically significant difference in saliva samples between groups.

Conclusion

Our results showed that different microRNAs may play role in salivary tumor pathogenesis according to biological behavior. Although there was no difference in saliva samples between groups, according to tissue and serum samples miR-21 and 30e may have an important role; since they were down-regulated in benign tumors whereas up-regulated in malignant ones.

Expression of miR-23a by apoptotic regulators in human cancer: A review

MicroRNAs play fundamental roles in mammalian development, differentiation and cellular homeostasis by regulating essential processes such as proliferation, migration, metabolism, migration and cell death. These small non-coding RNAs are also responsible in RNA silencing, and in many developmental and pathological processes. Not surprisingly, miR-23a misexpression contributes to numerous diseases including cancer where certain miRNA genes have been classified as either oncogenes or tumor suppressor genes. Since a single microRNA is capable of targeting a large number of mRNA sequences, de-regulated miRNA expression has the ability to alter various transcripts and activate a wide range of cancer-related pathways. This review article documents reduced levels of mature miR-23a in various tumors, primarily due to epigenetic silencing or alterations in biogenesis pathways. Moreover, inhibition of miR-23a in stressed cells represent a general mechanism for inducing apoptosis and these microRNAs are showed to be regulated by molecular chaperon HSP70. Microarray expression analysis of miRNA overexpression or depletion is now used in the characterization of cancer development pathways and as a biomarker for early cancer detection.

MicroRNA-23a and MicroRNA-27a Mimic Exercise by Ameliorating CKD-Induced Muscle Atrophy

Muscle atrophy is a frequent complication of CKD, and exercise can attenuate the process. This study investigated the role of microRNA-23a (miR-23a) and miR-27a in the regulation of muscle mass in mice with CKD. These miRs are located in a gene cluster that is regulated by the transcription factor NFAT. CKD mice expressed less miR-23a in muscle than controls, and resistance exercise (muscle overload) increased the levels of miR-23a and miR-27a in CKD mice. Injection of an adeno-associated virus encoding the miR-23a/27a/24-2 precursor RNA into the tibialis anterior muscles of normal and CKD mice led to increases in mature miR-23a and miR-27a but not miR-24-2 in the muscles of both cohorts. Overexpression of miR-23a/miR-27a in CKD mice attenuated muscle loss, improved grip strength, increased the phosphorylation of Akt and FoxO1, and decreased the activation of phosphatase and tensin homolog (PTEN) and FoxO1 and the expression of TRIM63/MuRF1 and FBXO32/atrogin-1 proteins. Provision of miR-23a/miR-27a also reduced myostatin expression and downstream SMAD-2/3 signaling, decreased activation of caspase-3 and -7, and increased the expression of markers of muscle regeneration. Lastly, in silico miR target analysis and luciferase reporter assays in primary satellite cells identified PTEN and caspase-7 as targets of miR-23a and FoxO1 as a target of miR-27a in muscle. These findings provide new insights about the roles of the miR-23a/27a-24-2 cluster in CKD-induced muscle atrophy in mice and suggest a mechanism by which exercise helps to maintain muscle mass.

A pilot study: Screening target miRNAs in tissue of nonsyndromic cleft lip with or without cleft palate

Nonsyndromic cleft lip with or without cleft palate (NSCLP) has been recognized as a condition resulting from a combination of environmental and genetic factors. Studies have demonstrated that microRNAs (miRNAs) are involved in embryonic development. However, few studies have focused on screening potential target miRNAs in human NSCLP tissue. Using microarray-based miRNA expression profiling, miRNA expression was compared in tissue samples from 4 NSCLP patients and 4 healthy control subjects. Two hundred and fifty-four miRNAs were found to be differentially expressed. Changes in Homo sapiens (hsa)-miR-24-3p, hsa-miR-27b-3p, hsa-miR-205-5p, hsa-miR-1260b and hsa-miR-720 were of particular interest with respect to Wnt signaling (fold-changes were 12.5, 12.2, 12.1, 12.3 and 10.5, respectively; P<0.005 for all). The levels of hsa-miR-24-3p, hsa-miR-1260b and hsa-miR-205-5p were higher in tissues from NSCLP patients than in those from controls according to PCR analysis. Hsa-miR-24-3p, hsa-miR-1260b and hsa-miR-205-5p may be candidate miRNAs involved in the etiology of NSCLP via Wnt signaling.

High-throughput sequencing identifies HIV-1-replication- and latency-related miRNAs in CD4+ T cell lines

MicroRNAs are potent gene expression regulators involved in regulating various biological processes, including host-pathogen interactions. In this study, we used high-throughput sequencing to investigate cellular miRNA signatures related to HIV-1 replication and latent infection in CD4⁺ T cell lines, which included HIV-1-replicating H9/HTLV-IIIB, HIV-1-latently-infected CEM-Bru cells, and their parental uninfected H9 and CEM-SS cells. Relatively few miRNAs were found to be modulated by HIV-1 replication or latent infection, while the cell-lineage-specific miRNA difference was more pronounced, irrespective of HIV-1 infection. In silico analysis showed that some of our HIV-1 infection-regulated miRNA profiles echoed previous studies, while others were novel. In addition, some of the miRNAs that were differentially expressed between the productively and latently infected cells seemed to participate in shaping the differential infection state. Thus, the newly identified miRNA profiles related to HIV-1 replication and latency provide information about the interplay between HIV-1 and its host.

HIC1 and miR-23~27~24 clusters form a double-negative feedback loop in breast cancer

MicroRNAs (miRNAs) have emerged as a major regulator of the initiation and progression of human cancers, including breast cancer. However, the cooperative effects and transcriptional regulation of multiple miRNAs, especially miRNAs that are present in clusters, remain largely undiscovered. Here we showed that all members of the miR-23~27~24 clusters are upregulated and function as oncogenes in breast cancer and simultaneously target HIC1. Furthermore, we found that HIC1 functions as a transcriptional repressor to negatively control the expression of miR-23~27~24 clusters and forms a double-negative (overall positive) feedback loop. This feedback regulatory pathway is important because overexpression of miR-23~27~24 clusters can remarkably accelerate tumor growth, whereas restoration of HIC1 significantly blocks tumor growth in vivo. A mathematical model was created to quantitatively illustrate the regulatory circuit. Our finding highlights the cooperative effects of miRNAs in a cluster and adds another layer of complexity to the miRNA regulatory network. This study may also provide insight into the molecular mechanisms of breast cancer progression.

Use of Mature miRNA Strand Selection in miRNAs Families in Cervical Cancer Development

Aberrant miRNA expression is well recognized as a cancer hallmark, nevertheless miRNA function and expression does not always correlate in patients tissues and cell lines studies. In addition to this issue, miRNA strand usage conduces to increased cell signaling pathways modulation diversifying cellular processes regulation. In cervical cancer, 20 miRNA families are involved in carcinogenesis induction and development to this moment. These families have 5p and 3p strands with different nucleotide (nt) chain sizes. In general, mature 5p strands are larger: two miRNAs of 24 nt, 24 miRNAs of 23 nt, 35 miRNAs of 22 nt and three miRNAs of 21 nt. On the other hand, the 3p strands lengths observed are: seven miRNAs of 23 nt, 50 miRNAs of 22 nt, six miRNAs of 21 nt and four miRNAs of 20 nt. Based on the analysis of the 20 miRNA families associated with cervical cancer, 67 3p strands and 65 5p strands are selected suggesting selectivity and specificity mechanisms regulating cell processes like proliferation, apoptosis, migration, invasion, metabolism and Warburg effect. The insight reviewed here could be used in the miRNA based therapy, diagnosis and prognosis approaches.

miR clusters target cellular functional complexes by defining their degree of regulatory freedom

Using the two paralog miR-23∼27∼24 clusters as an example and combining experimental and clinical data in a systematical approach to microRNA (miR) function and dysregulation, a complex picture of their roles in cancer is drawn. Various findings appear to be contradictory to a larger extent and cannot be fully explained by the classical regulatory network models and feedback loops that are mainly considered by one-to-one regulatory interactions of the involved molecules. Here, we propose an extended model of the regulatory role of miRs that, at least, supplements the usually considered single/oligo-target regulation of certain miRs. The cellular availability of the participating miR members in this model reflects an upper hierarchy level of intracellular and extracellular environmental influences, such as neighboring cells, soluble factors, hypoxia, chemotherapeutic drugs, and irradiation, among others. The novel model is based on the understanding of cellular functional complexes, such as for apoptosis, migration, and proliferation. These complexes consist of many regulatory components that can be targeted by miR cluster members to a different extent but may affect the functional complex in different ways. We propose that the final miR-related effect is a result of the possible degree of regulatory freedom provided by the miR effects on the whole functional complex structure. This degree of regulatory freedom defines to which extent the cellular functional complex can react in response to regulatory triggers, also understood as sensitization (more regulatory response options) or de-sensitization (less regulatory response options) of the system rather than single molecules.

Role of miR-24, Furin, and Transforming Growth Factor-β1 Signal Pathway in Fibrosis After Cardiac Infarction

BACKGROUND Cardiac fibrosis after primary infarction is a type of pathological phenomena as shown by increased collagen in myocardial cells. Transforming growth factor (TGF)-β1 is a critical factor participating in myocardial fibrosis. A previous study has shown the inhibitory role on TGF-β1 by microRNA-24 (miR-24) via targeting Furin. This study thus investigated the role of miR-24 and Furin/TGF-β1 in rat myocardial fibrosis. MATERIAL AND METHODS A total of 40 adult SD rats (both males and females) were prepared for myocardial infarction model by ligating the descending branch of left coronary artery after anesthesia. HE staining was performed to observe myocardial fibrosis after 1, 2, and 4 weeks. Tissue RNA was extracted to detect mRNA levels of Furin, TGF-β1, and miR-24 by real-time PCR. Western blotting was used to quantify protein expression of Furin and TGF-β1 in myocardial tissues. RESULTS Increased connective tissues were observed in myocardial tissues at 4 weeks after infarction by HE staining, which also revealed widening of the intra-myocardial cleft, along with more inflammatory cells and fibroblast hypertrophy. miR-24 expression was significantly depressed at 2 and 4 weeks after cardiac infarction (p<0.05). mRNA levels of Furin and TGF-β1 were elevated after infarction (p<0.05). With prolonged time periods of myocardial infarction, protein levels of Furin and TGF-β1 were further increased. The level of miR-24 was positively correlated with left ventricular end-diastolic diameter, left ventricular systolic diameter, and left ventricular ejection fraction. However, the level of Furin or TGF-β1 was negatively correlated with the above parameters. CONCLUSIONS This study demonstrated the important role of abnormal expression of miR-24 in myocardial fibrosis after infarction, and may provide drug targets for treating myocardial fibrosis.

A MicroRNA Cluster miR-23-24-27 Is Upregulated by Aldosterone in the Distal Kidney Nephron Where it Alters Sodium Transport

The epithelial sodium channel (ENaC) is expressed in the epithelial cells of the distal convoluted tubules, connecting tubules, and cortical collecting duct (CCD) in the kidney nephron. Under the regulation of the steroid hormone aldosterone, ENaC is a major determinant of sodium (Na⁺ ) and water balance. The ability of aldosterone to regulate microRNAs (miRs) in the kidney has recently been realized, but the role of miRs in Na⁺ regulation has not been well established. Here we demonstrate that expression of a miR cluster mmu-miR-23-24-27, is upregulated in the CCD by aldosterone stimulation both in vitro and in vivo. Increasing the expression of these miRs increased Na⁺ transport in the absence of aldosterone stimulation. Potential miR targets were evaluated and miR-27a/b was verified to bind to the 3'-untranslated region of intersectin-2, a multi-domain protein expressed in the distal kidney nephron and involved in the regulation of membrane trafficking. Expression of Itsn2 mRNA and protein was decreased after aldosterone stimulation. Depletion of Itsn2 expression, mimicking aldosterone regulation, increased ENaC-mediated Na⁺ transport, while Itsn2 overexpression reduced ENaC's function. These findings reinforce a role for miRs in aldosterone regulation of Na⁺ transport, and implicate miR-27 in aldosterone's action via a novel target. J. Cell. Physiol. 232: 1306-1317, 2017. © 2016 Wiley Periodicals, Inc.

The roles of oncogenic miRNAs and their therapeutic importance in breast cancer

Since the discovery of tumour suppressive miRNA in 2002, the dysregulation of miRNAs was implicated in many cancers, exhibiting both tumour suppressive and oncogenic roles. Dysregulation of miRNAs was found to be involved in the initiation of oncogenesis, as well as the progression, invasion and metastasis of cancers. While normal miRNA inhibitory functions help regulate gene expression in the cell, oncogenic miRNA, when dysregulated can lead to suppression of critical pathways that control apoptosis, cell cycle progression, growth and proliferation. This suppression allows for the upregulation of pro-oncogenic factors that drive cell survival, growth and proliferation. Due to emerging discoveries, oncogenic miRNAs are proving to be a critical component in cancers, such as breast cancer, and may provide novel avenues for cancer treatment. In this article, we discuss the roles of the most studied oncogenic miRNAs in breast cancer including clusters and families involved as well as the less studied and recently discovered oncogenic miRNAs. These miRNAs provide valuable information into the complexity of regulatory elements affected by their overexpression and the overall impact in the progression of breast cancer. Also, identifying miRNAs causing or leading to resistance or sensitivity to current anti-cancer drugs prior to treatment may lead to an improvement in treatment selection and overall patient response. This review summarizes known and recently discovered miRNAs in literature found to have oncogenic roles in breast cancer initiation and the progression, invasion and metastasis of the disease.

Different levels of serum microRNAs in prostate cancer and benign prostatic hyperplasia: evaluation of potential diagnostic and prognostic role

Introduction

Diagnosis of prostate cancer (PCa) is based on prostate biopsy that is performed when prostate specific antigen (PSA) is persistently altered over time and/or abnormal digital rectal examination is found. Serum PSA levels increase in both PCa and benign prostatic hyperplasia, leading to an increased number of unnecessary biopsies. There is an urgent need to unravel PCa-specific molecular signatures.

Patients and methods

This study aimed at characterizing a panel of circulating micro RNAs (miRNAs) that could distinguish PCa from benign prostatic hyperplasia in a population of age-matched patients with increased PSA levels. Both miRNAs targeting genes involved in PCa onset and miRNAs whose role in PCa has been highlighted in other studies were included. For this purpose, let-7c, let-7e, let-7i, miR-26a-5p, miR-26b-5p, miR-24-3p, miR-23b-3p, miR-27-b-3p, miR-106a-5p, miR-20b-5p, miR-18b-5p, miR-19b-2-5p, miR-363-3p, miR-497, miR-195, miR-25-3p, miR-30c-5p, miR-622, miR-874-3p, miR-346 and miR-940 were assayed through real-time PCR in 64 patients with PCa and compared with 60 patients with benign prostatic hyperplasia. The ability of miRNAs to predict the stage of disease was also analyzed.

Results

Let-7c, let-7e, let-7i, miR-26a-5p, miR-26b-5p, miR-18b-5p and miR-25-3p were able to discriminate patients with PCa from those harboring benign prostatic hyperplasia, both presenting altered PSA levels (>3 ng/mL). MiR-25-3p and miR-18b-5p showed the highest sensitivity and specificity to predict PCa, respectively. The combination of these two miRNAs improved the overall sensitivity. A correlation between pathological Gleason score and miRNA expression levels was reported; miR-363-3p, miR-26a-5p, miR-26b-5p, miR-106a-5p, miR-18b-5p, miR-25-3p and let-7i decreased in expression concomitantly with an increase in malignancy.

Conclusion

This study confirms serum miRNAs to be reliable candidates for the development of minimally invasive biomarkers for the diagnosis and prognosis of PCa, particularly in those cases where PSA acts as a flawed marker.

miRNA-24-3p promotes cell proliferation and regulates chemosensitivity in head and neck squamous cell carcinoma by targeting CHD5

Aim: To investigate the role of miR-24-3p in tumorigenesis and chemosensitivity in head and neck squamous cell carcinoma (HNSCC). Methods: Growth rate and colony formation assays were performed after transfection with miR-24-3p mimic and inhibitor in cultured SCC-15 cells, followed by a CellTiter-Glo® assay. Western blot and luciferase assays were performed to investigate the direct target of miR-24-3p. Xenograft mouse model was used to evaluate combinatorial effects of miR-24-3p inhibitor and 5-fluorouracil. Results & conclusion: Inhibition of miR-24-3p reduced cell proliferation, colony formation efficiency and reversed chemoresistance in HNSCC cells. CHD5 is the direct target of miR-24-3p which is required for the regulatory role of miR-24-3p in chemoresistance. miR-24-3p may represent a new therapeutic target for the improvement of clinical outcome in HNSCC.

Effect of miR-23a on anoxia-induced phenotypic transformation of smooth muscle cells of rat pulmonary arteries and regulatory mechanism

We investigated the possible implication of miR-23a in anoxia-induced phenotypic transformation of the pulmonary arterial smooth muscle and studied the mechanism of upregulation of miR-23a expression in anoxia. The collagenase digestion method was used for preparing rat primary pulmonary artery smooth muscle cell (PASMC) culture. SM-MHC, SM-α-actin, calponin-1 and SM22α protein expression levels were evaluated using western blot analysis after the ASMCs were subjected to anoxia treatment (3% O₂). Transfection with miR-23a mimics were conducted when PASMCs were under normoxia and anoxia conditions. EdU staining was used to detect the proliferative activity of PASMCs. Cells were transfected with HIF-1α specific siRNA under anoxia condition. RT-qPCR was used to detect miR-23a expression in PASMCs. Chromatin immunoprecipitation method was employed to verify the binding sites of HIF-1α. The dual-luciferase reporter gene was used to study the role of HIF-1 and its binding sites. Rat hypoxic pulmonary hypertension models were established to study the expression of miR-23a using RT-qPCR method and to verify the expression of miR-23a in the arteriole of the rat pulmonary. Our results showed that compared with normoxia condition, under anoxia condition (3% O₂), the expression levels of the contractile phenotype marker proteins decreased significantly after 24 and 48 h. The positive rate of the EdU staining increased significantly and the expression of miR-23a increased. Transfection with miR-23a-mimic downregulated the expression of contractile marker proteins and improved the positive rate of the EdU staining under normoxia. Anoxia and transfection with HIF-1α enhanced the activity of the wild-type Luc-miR-23a-1 (WT) reporter gene. We concluded that miR-23a participated in the anoxia-induced phenotypic transformation of PASMCs. Increased expression of miR-23a under anoxia may primarily be due to miR-23a-1 and miR-23a-3 upregulation. The anoxia-induced upregulation of miR-23a was regulated by HIF-1.

Circulating microRNA Profiles as Liquid Biopsies for the Characterization and Diagnosis of Fibromyalgia Syndrome

This work was aimed at investigating the circulating microRNA (miRNA) profiles in serum and saliva of patients affected by fibromyalgia syndrome (FM), correlating their expression values with clinical and clinimetric parameters and to suggest a mathematical model for the diagnosis of FM. A number of 14 FM patients and sex- and age-matched controls were enrolled in our study. The expression of a panel of 179 miRNAs was evaluated by qPCR. Statistical analyses were performed in order to obtain a mathematical linear model, which could be employed as a supporting tool in the diagnosis of FM. Bioinformatics analysis on miRNA targets were performed to obtain the relevant biological processes related to FM syndrome and to characterize in details the disease. Six miRNAs were found downregulated in FM patients compared to controls. Five of these miRNAs have been included in a linear predictive model that reached a very high sensitivity (100 %) and a high specificity (83.3 %). Moreover, miR-320b displayed a significant negative correlation (r = -0.608 and p = 0.036) with ZSDS score. Finally, several biological processes related to brain function/development and muscular functions were found potentially implicated in FM syndrome. Our study suggests that the study of circulating miRNA profiles coupled to statistical and bioinformatics analyses is a useful tool to better characterize the FM syndrome and to propose a preliminary model for its diagnosis.

Effects of MicroRNA-23a on Differentiation and Gene Expression Profiles in 3T3-L1 Adipocytes

MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate growth, development, and programmed death of cells. A newly-published study has shown that miRNA-23a could regulate 3T3-L1 adipocyte differentiation. Here, we identified miRNA-23a as a negative regulator of 3T3-L1 adipocyte differentiation again. Over-expression of miRNA-23a inhibited differentiation and decreased lipogenesis as well as down-regulated mRNA and protein expression of both peroxisome proliferator-activated receptor (PPAR) γ and fatty acid binding protein (FABP) 4, whereas knock down of miRNA-23a showed the opposite effects on differentiation as well as increasing the number of apoptotic cells. Additionally, digital gene expression profiling sequencing (DGE-Seq) was used to assay changes in gene expression profiles following alterations in the level of miR-23a. In total, over-expression or knock down of miRNA-23a significantly changed the expression of 313 and 425 genes, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that these genes were mainly involved in the stress response, immune system, metabolism, cell cycle, among other pathways. Additionally, the signal transducer and activator of transcription 1 (Stat1) was shown to be a target of miRNA-23a by computational and dual-luciferase reporter assays that indicated Janus Kinase (Jak)-Stat signal pathway was implicated in regulating adipogenesis mediated by miRNA-23a in adipocytes.

From Nutrient to MicroRNA: a Novel Insight into Cell Signaling Involved in Skeletal Muscle Development and Disease

Skeletal muscle is a remarkably complicated organ comprising many different cell types, and it plays an important role in lifelong metabolic health. Nutrients, as an external regulator, potently regulate skeletal muscle development through various internal regulatory factors, such as mammalian target of rapamycin (mTOR) and microRNAs (miRNAs). As a nutrient sensor, mTOR, integrates nutrient availability to regulate myogenesis and directly or indirectly influences microRNA expression. MiRNAs, a class of small non-coding RNAs mediating gene silencing, are implicated in myogenesis and muscle-related diseases. Meanwhile, growing evidence has emerged supporting the notion that the expression of myogenic miRNAs could be regulated by nutrients in an epigenetic mechanism. Therefore, this review presents a novel insight into the cell signaling network underlying nutrient-mTOR-miRNA pathway regulation of skeletal myogenesis and summarizes the epigenetic modifications in myogenic differentiation, which will provide valuable information for potential therapeutic intervention.