Prognostic value of microRNA-9 and microRNA-155 expression in triple-negative breast cancer

MicroRNAs (miRNAs) are involved in regulation of epithelial-mesenchymal transition (EMT) during breast cancer progression. The purpose of this study was to analyze the clinicopathologic significance of expression of EMT-related miRNAs, miR-9 and miR-155, in triple-negative breast cancers (TNBCs). We analyzed relative expression levels of miR-9 and miR-155 in 190 surgically resected TNBC specimens using quantitative real-time polymerase chain reaction. Then we analyzed the relationship between these miRNA expression levels and EMT marker expression (vimentin, smooth muscle actin [SMA], osteonectin, N-cadherin, E-cadherin, CD146, and ZEB1) assessed by immunohistochemistry. We also evaluated the prognostic significance of these miRNA expression levels. While miR-9 expression level showed a positive correlation with pT category, miR-155 expression level did not correlate with any clinicopathologic features of TNBCs. In relation to EMT phenotype, miR-9 expression was not associated with EMT marker expression except for SMA. However, miR-155 expression level correlated inversely with the expression of several EMT markers including SMA, osteonectin, and CD146. We observed that both miR-9 and miR-155 could be prognostic markers in TNBC in opposite ways; high level of miR-9 expression showed significant association with poor disease-free survival and distant metastasis-free survival (DMFS) in TNBC, while high level of miR-155 expression was associated with better DMFS. Our study suggests that expression levels of both miR-9 and miR-155 can serve as candidates for prognostic biomarkers in TNBCs.

Expression of hsa-miR-9 and MYC Copy Number Variation in Hereditary Diffuse Gastric Cancer

BACKGROUND/AIM

Approximately, 15-50% of families affected by hereditary diffuse gastric cancer (HDGC) exhibit CDH1 germline mutations. CDH1 gene encodes E-cadherin, protein essential to the cell-cell contact of gastric epithelium. Studies have shown that hsa-miR-9 participates in this protein downregulation. Moreover, MYC is responsible for the transcription of hsa-miR-9-3. In the present study, hsa-miR-9 expression and MYC copy number variation were investigated to elucidate the hsa-miR-9 role in HDGC.

PATIENTS AND METHODS

Tumor samples were obtained from nine individuals with HDGC history belonging to four Brazilian families. Then, relative quantification of hsa-miR-9 expression and MYC gene copy number variation analysis were performed by real-time PCR.

RESULTS

In all the samples, an overexpression of hsa-miR-9 and an increased MYC copy number (≥3 copies) were observed.

CONCLUSION

hsa-miR-9 acts as an oncomiR in HDGC. In addition, we suggest that hsa-miR-9 acts as second event in individuals with HDGC carrying CDH1 gene germinline mutations.

MicroRNA-mediated disruption of dendritogenesis during a critical period of development influences cognitive capacity later in life

The prenatal period of cortical development is important for the establishment of neural circuitry and functional connectivity of the brain; however, the molecular mechanisms underlying this process remain unclear. Here we report that disruption of the actin-cytoskeletal network in the developing mouse prefrontal cortex alters dendritic morphogenesis and synapse formation, leading to enhanced formation of fear-related memory in adulthood. These effects are mediated by a brain-enriched microRNA, miR-9, through its negative regulation of diaphanous homologous protein 1 (Diap1), a key organizer of the actin cytoskeletal assembly. Our findings not only revealed important regulation of dendritogenesis and synaptogenesis during early brain development but also demonstrated a tight link between these early developmental events and cognitive functions later in life.

MiR-9 Promotes Apoptosis Via Suppressing SMC1A Expression in GBM Cell Lines

Objective:

Glioblastomas multiforme (GBM) is the most malignant brain cancer, which presented vast genomic variation with complicated pathologic mechanism.

Method:

MicroRNA is a delicate post-transcriptional tuner of gene expression in the organisms by targeting and regulating protein coding genes. MiR-9 was reported as a significant biomarker for GBM patient prognosis and a key factor in regulation of GBM cancer stem cells. To explore the effect of miR-9 on GBM cell growth, we over expressed miR-9 in U87 and U251 cells. The cell viability decreased and apoptosis increased after miR-9 overexpression in these cells. To identify the target of miR-9, we scanned miR-9 binding site in the 3’UTRs region of expression SMC1A (structural maintenance of chromosomes 1A) genes and designed a fluorescent reporter assay to measure miR-9 binding to this region. Our results revealed that miR-9 binds to the 3’sUTR region of SMC1A and down-regulated SMC1A expression.

Result:

Our results indicated that miR-9 was a potential therapeutic target for GBM through triggering apoptosis of cancer cells.

LincRNA-p21 inhibits invasion and metastasis of hepatocellular carcinoma through miR-9/E-cadherin cascade signaling pathway molecular mechanism

In the previous study, it was found that long intergenic noncoding RNA-p21 (lincRNA-p21) was downregulated in hepatocellular carcinoma (HCC) and lincRNA-p21 overexpression inhibited tumor invasion through inducing epithelial–mesenchymal transition. However, the underlying mechanism was not fully elaborated. In this study, lincRNA-p21 expression was measured in 12 paired HCC and nontumor adjacent normal tissues by quantitative real-time polymerase chain reaction. The effects of lincRNA-p21 on HCC cells were studied using lentivirus expressing lincRNA-p21 vector in vitro. The association between lincRNA-p21 level and miR-9 level was tested with the Spearman rank correlation. The effects of miR-9 on HCC cells were studied by using miR-9 inhibitor in vitro. Luciferase assay was used to validate the target of miR-9. The results showed that lincRNA-p21 was downregulated in human HCC tissues and cell lines. LincRNA-p21 overexpression significantly inhibited HCC cell migration and invasion in vitro. Besides, lincRNA-p21 negatively regulated miR-9 expression level, and miR-9 was upregulated in human HCC tissues and cells. MiR-9 knockdown inhibited HCC cell migration and invasion in vitro. Finally, the luciferase assay results showed that E-cadherin was a direct target of miR-9. The expression level of E-cadherin was found to be regulated by lincRNA-p21 and miR-9. Altogether, the results suggested that lincRNA-p21 inhibits migration and invasion of HCC cells through regulating miR-9-mediated E-cadherin cascade signaling pathway.

Diabetic nephropathy: serum miR-9 confers a poor prognosis in and is associated with level changes of vascular endothelial growth factor and pigment epithelium-derived factor

OBJECTIVE

To investigate the relationship between the serum level of miR-9 and the progression of diabetic nephropathy (DN) and related molecular mechanisms.

RESULTS

Thirty-five healthy subjects and 140 DN patients were divided into five groups: control, DN I-II, DN III, DN IV and DN V. Serum level of miR-9 was measured by real-time qPCR. Serum levels of vascular endothelial growth factor (VEGF), pigment epithelium-derived factor (PEDF) lipids, fasting glucose, insulin, hemoglobin A1c (HBA1c), creatinine, fibrinogen and insulin resistance (HOMA-IR) were also measured. The results show that the levels of miR-9, PEDF and VEGF are increased with DN progression (P < 0.05). miR-9, VEGF and PEDF are independent risk factors of DN (R² = 0.430). Spearman rank correlation analysis showed that miR-9 level is positively related to the levels of VEGF, PEDF, cholesterol, triglyceride, fasting glucose, fasting insulin, HBA1c, creatinine, fibrinogen and HOMA-IR (P < 0.05).

CONCLUSIONS

Serum miR-9 is a potential marker for conferring a poor prognosis in DN and associated with the levels of VEGF, PEDF and biochemical indices.

miR-124 and miR-9 mediated downregulation of HDAC5 promotes neurite development through activating MEF2C-GPM6A pathway

The class IIa histone deacetylases (HDACs) play important roles in the central nervous system during diverse biological processes such as synaptic plasticity, axon regeneration, cell apoptosis, and neural differentiation. Although it is known that HDAC5 regulates neuronal differentiation, neither the physiological function nor the regulation of HDAC5 in neuronal differentiation is clear. Here, we identify HDAC5 as an inhibitor of neurite elongation and show that HDAC5 is regulated by the brain enriched microRNA miR-124 and miR-9. We discover that HDAC5 inhibits neurite extension both in differentiated P19 cells and primary neurons. We also show that the neuronal membrane glycoprotein GPM6A (M6a) is a direct target gene of HDAC5 regulated transcriptional factor MEF2C. HDAC5 inhibits neurite elongation, acting at least partially via a MEF2C/M6a signaling pathway. We also confirmed the miR-124/miR-9 regulated HDAC5-MEF2C-M6a pathway regulates neurite development in primary neurons. Thus, HDAC5 emerges as a cellular conductor of MEF2C and M6a activity and is regulated by miR-124 and miR-9 to control neurite development.

Notch/Hes signaling and miR-9 engage in complex feedback interactions controlling neural progenitor cell proliferation and differentiation

Canonical Notch signaling has diverse functions during nervous system development and is critical for neural progenitor self-renewal, timing of differentiation and specification of various cell fates. A key feature of Notch-mediated self-renewal is its fluctuating activity within the neural progenitor cell population and the oscillatory expression pattern of the Notch effector Hes1 and its target genes. A negative feedback loop between Hes1 and neurogenic microRNA miR-9 was found to be part of this oscillatory clock. In a recent study we discovered that miR-9 expression is further modulated by direct binding of the Notch intracellular domain/RBPj transcriptional complex to the miR-9_2 promoter. In turn, miR-9 not only targets Hes1 but also Notch2 to attenuate Notch signaling and promote neuronal differentiation. Here, we discuss how the two interwoven feedback loops may provide an additional fail-save mechanism to control proliferation and differentiation within the neural progenitor cell population. Furthermore, we explore potential implications of miR-9-mediated regulation of Notch/Hes1 signaling with regard to neural progenitor homeostasis, patterning, timing of differentiation and tumor formation.

MicroRNA-9 plays a role in interleukin-10-mediated expression of E-cadherin in acute myelogenous leukemia cells

We previously showed that the CD82/signal transducer and activator of transcription/interleukin-10 (IL-10) axis is activated in CD34⁺ /CD38^- AML cells that favor the bone marrow microenvironment. The present study explored the novel biological function of IL-10 in regulation of expression of adhesion molecules in AML cells and found that exposing AML cells to IL-10 induced expression of E-cadherin, but not other adhesion molecules, including VLA4, CD29, and LFA1. Downregulation of E-cadherin with an siRNA suppressed the adhesion of leukemia cells to bone marrow-derived mesenchymal stem cells and enhanced the anti-leukemia effect of cytarabine. A microRNA (miRNA) database search identified an miR-9 as a candidate miRNA binding onto the 3'-UTR of E-cadherin and regulating its expression. Notably, treatment of leukemia cells with IL-10 decreased miR-9 expression through hypermethylation of the miR-9 CpG islands. In addition, downregulation of DNA methyltransferase 3A by siRNAs decreased E-cadherin expression in parallel with an increase in levels of miR-9 in leukemia cells. Notably, short hairpin RNA-mediated IL-10 downregulation impaired engraftment of human AML cells and enhanced the anti-leukemia effect of cytarabine in conjunction with miR-9 upregulation and E-cadherin downregulation in a human AML xenograft model. Taken together, the IL-10/E-cadherin axis may be a promising therapeutic target for treating AML.

MicroRNA-9 Inhibits NLRP3 Inflammasome Activation in Human Atherosclerosis Inflammation Cell Models through the JAK1/STAT Signaling Pathway

BACKGROUND/AIMS

MicroRNA-9 (miR-9) is involved in inflammatory reaction in atherosclerosis; however, its function and regulatory mechanisms remain unclear. We aimed to uncover the exact roles of miR-9 and downstream signaling pathways using in vitro human atherosclerosis models.

METHODS

We used oxidized low-density lipoprotein (oxLDL)-stimulated human THP-1 derived macrophages, oxLDL-stimulated human primary peripheral blood monocytes and lipopolysaccharides (LPS) or Alum-stimulated human THP-1 derived macrophages as in vitro atherosclerosis inflammation models. Transient transfection of over-expression vectors, small interference RNAs (siRNAs) or antisense oligonucleotides was used to regulate intracellular protein or miR-9 levels. Cell responses and signal transduction were detected by multiple assays including Western blotting, enzyme-linked immunosorbent assay (ELISA) and luciferase reporter assay.

RESULTS

MiR-9 inhibited while anti-miR-9 antisense oligonucleotides induced interleukin-1 beta (IL-1β) and NLRP3 inflammasome activation in all in vitro models. Janus kinase 1 (JAK1) and matrix metalloproteinase 13 (MMP-13) were identified as the target genes of miR-9. In oxLDL-stimulated human THP-1 derived macrophages, knockdown of JAK1 by siRNA blocked the phosphorylation of signal transducer and activator of transcription 1 (STAT1) and mimicked the effects of miR-9. In the same model, JAK1 knockdown blocked the phosphorylation of NF-κB p65 in the nuclei and the phosphorylation of NF-κB IκBα in the cytoplasm.

CONCLUSIONS

Our study demonstrated that miR-9 could inhibit activation of the NLRP3 inflammasome and attenuate atherosclerosis-related inflammation, likely through the JAK1/STAT1 signaling pathway. Therefore, miR-9 may serve as a potential therapeutic target for atherosclerosis.

MiR-9-5p Down-Regulates PiT2, but not PiT1 in Human Embryonic Kidney 293 Cells

PiT1 (SLC20A1) and PiT2 (SLC20A2) are members of the mammalian type-III inorganic phosphate transporters and recent studies linked SLC20A2 mutations with primary brain calcifications. MicroRNAs (miRNAs) are endogenous noncoding regulatory RNAs and MicroRNA-9 (miR-9) modulates neurogenesis but is also involved with different types of cancer. We evaluated possible interactions between miR-9 and the phosphate transporters (PiT1 and PiT2). SLC20A2, platelet-derived growth factor receptor beta (PDGFRB) and Fibrillin-2 (FBN2) showed binding sites with high affinity for mir-9, In silico. miR-9 mimic was transfected into HEK293 cells and expression was confirmed by RT-qPCR. Overexpression of miR-9 in these cells caused a significant reduction in PiT2 and FBN2. PDGFRB appeared to be decreased, but was not significantly down-regulated. PiT1 showed no significant difference relative to controls. The down-regulation of PiT2 protein by miR-9 was confirmed by western blotting. In conclusion, we showed that miR-9 can down-regulate PiT2, in HEK293 cells. [corrected].

miR-9 functions as a tumor inhibitor of cell proliferation in epithelial ovarian cancer through targeting the SDF-1/CXCR4 pathway

The current study aimed to investigate the potential role of miR-9 in the inhibition of ovarian cancer progression through the stromal cell-derived factor-1 (SDF-1)/ C-X-C chemokine receptor type 4 (CXCR4) pathway and to provide a theoretical basis for the diagnosis and treatment of ovarian cancer. Human ovarian cancer OVCAR-3 cells were transfected with miR-9 short hairpin RNA (shRNA). The effect of miR-9 on the mRNA expression levels of CXCR4 were analyzed using reverse transcription-quantitative polymerase chain reaction. The effects of miR-9 on OVCAR-3 cell proliferation, invasion and apoptotic ability were detected using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide assay, Matrigel method, and Annexin V-fluorescein isothiocyanate flow cytometry, respectively. In addition, expression levels of SDF-1/CXCR4 pathway associated proteins were determined by western blot analysis. mRNA expression levels of CXCR4 in OVCAR-3 cells transfected with miR-9 shRNA was significantly downregulated compared with the blank and control groups (P<0.05). Furthermore, compared with the two control groups, the current results revealed that miR-9 inhibited cell proliferation, suppressed invasive ability and induced cell apoptosis in OVCAR-3 cells (P<0.05). Finally, it was observed that miR-9 functioned as a tumor inhibitor through the SDF-1/CXCR4 pathway by suppressing the expression levels of extracellular signal-regulated kinase 1 (ERK1), ERK2 and matrix metalloproteinase-9 proteins. The present study suggested that miR-9 may function as a promising tumor inhibitor for ovarian cancer through targeting the SDF-1/CXCR4 pathway.

MicroRNA-9 inhibits the gastric cancer cell proliferation by targeting TNFAIP8

BACKGROUND AND OBJECTIVES

MicroRNA-9 is frequently dysregulated in many human carcinoma types, including gastric cancer (GC). Previous studies demonstrated that the expression of TNFAIP8 in GC is correlated with tumour occurrence, development, invasion, metastasis and prognosis. However, till now, the relationship between MicroRNA-9 and TNFAIP8 in GC has not been reported.

MATERIALS AND METHODS

Levels of miR-9 and TNFAIP8 expression in GC tissues and in human GC cell lines were studied using qualitative real-time PCR (qRT-PCR) and Western blotting. Cell viability was detected using the CCK-8 and clone formation assays. A dual-luciferase reporter system was used to confirm the target gene of miR-9.

RESULTS

We found that the expression level of MicroRNA-9 in GC tissues and cell lines was significantly lower than that in adjacent non-cancerous tissues and human immortalized gastric epithelial cell (GES) line, respectively. In addition, overexpression of MicroRNA-9 markedly inhibited GC cell proliferation in vitro and tumour growth in vivo. Further experiments revealed that TNFAIP8 was a direct and functional target of MicroRNA-9 in GC and overexpression of MicroRNA-9 obviously down-regulated the expression of TNFAIP8, which was involved in the gastric carcinogenesis and cancer progression.

CONCLUSION

Our results suggested that MicroRNA-9-TNFAIP8 might represent a promising diagnostic biomarker for GC patients and could be a potential therapeutic target in the prevention and treatment of GC.

Cullin 4A (CUL4A), a direct target of miR-9 and miR-137, promotes gastric cancer proliferation and invasion by regulating the Hippo signaling pathway

Although Cullin 4A (CUL4A) is mutated or amplified in several human cancer types, its role in gastric cancer (GC) and the mechanisms underlying its regulation remain largely uncharacterized. In the present study, we report that the expression of CUL4A significantly correlated with the clinical stage of the tumor and lymph node metastasis, and survival rates were lower in GC patients with higher levels of CUL4A than in patients with lower CUL4A levels. The upregulation of CUL4A promoted GC cell proliferation and epithelial-mesenchymal transition (EMT) by downregulating LATS1-Hippo-YAP signaling. Knocking down CUL4A had the opposite effect in vitro and in vivo. Interestingly, CUL4A expression was inhibited by the microRNAs (miRNAs), miR-9 and miR-137, which directly targeted the 3′-UTR of CUL4A. Overexpression of miR-9 and miR-137 downregulated the CUL4A-LATS1-Hippo signaling pathway and suppressed GC cell proliferation and invasion in vitro. Taken together, our findings demonstrate that perturbations to miR-9/137-CUL4A-Hippo signaling contribute to gastric tumorigenesis, and suggest potential therapeutic targets for the future treatment of GC.

Double In situ Hybridization for MicroRNAs and mRNAs in Brain Tissues

MicroRNAs (miRNAs) participate in a variety of functions in the brain. Understanding the in vivo localization of miRNAs is an important step for uncovering their roles in brain function. However, the in situ detection of low-abundance miRNAs in brain tissues remains difficult and requires extensive optimization of in situ hybridization (ISH) protocols in individual laboratories. Thus, detailed information regarding experimental conditions would serve as a useful reference for researchers in this field. Here, we investigated and summarized the effects of adjusting a series of critical steps, including tissue fixation, probe accessibility and hybridization stringency, to standardize the currently used miRNA ISH procedures. As a result, we successfully detected several low-abundance miRNAs by ISH using the following experimental conditions: (1) use of fresh brain tissues, (2) digestion of brain samples with proteinase K, (3) LNA-probe hybridization at a temperature 37°C below the melting temperature of the RNA, (4) performance of high-stringency wash steps using 50% formamide in 1 × standard saline citrate (SSC) buffer. RT-PCR of the punched-out tissues using TaqMan^TM primers confirmed the ISH results. Finally, double-fluorescence ISH successfully demonstrated the colocalization of miRNAs and mRNAs. Thus, the detailed information regarding the miRNA ISH procedures used in this study may help to resolve the technical hurdles observed in the in vivo localization of miRNAs, and the elucidation of the specific roles of miRNAs.

Prognostic Value of microRNA-9 in Various Cancers: a Meta-analysis

Recently, there are more and more evidences from studies have revealed the association between microRNA-9 (miR-9) expression and outcome in multiple cancers, but inconsistent results have also been reported. It is necessary to rationalize a meta analysis of all available data to clarify the prognostic role of miR-9. Eligible studies were selected through multiple search strategies and the quality was assessed by MOOSE. Data was extracted from studies according to the key statistics index. All analyses were performed using STATA software. Twenty studies were selected in the meta-analysis to evaluate the prognostic role of miR-9 in multiple tumors. MiR-9 expression level was an independent prognostic biomarker for OS in tumor patients using multivariate and univariate analyses. High expression levels of miR-9 was demonstrated to associated with poor overall survival (OS) (HR = 2.23, 95 % CI: 1.56-3.17, P < 0.05) and recurrence free survival/progress free survival (RFS/PFS) (HR = 2.08, 95 % CI: 1.33-3.27, P < 0.05). Subgroup analysis showed that residence region (China and Japan), sample size, cancer type (solid or leukemia), follow-up months and analysis method (qPCR) did not alter the predictive value of miR-9 on OS in various cancers. Furthermore, no significant associations were detected for miR-9 expression and lymph node metastasis or distant metastasis. The present results suggest that promoted miR-9 expression is associated with poor OS in patients with general cancers.

WITHDRAWN: LncRNA TUG1 promotes breast cancer cell proliferation via inhibiting miR-9

Ahead of Print article withdrawn by publisher.

MiR-9 is overexpressed in spontaneous canine osteosarcoma and promotes a metastatic phenotype including invasion and migration in osteoblasts and osteosarcoma cell lines

Background

MicroRNAs (miRNAs) regulate the expression of networks of genes and their dysregulation is well documented in human malignancies; however, limited information exists regarding the impact of miRNAs on the development and progression of osteosarcoma (OS). Canine OS exhibits clinical and molecular features that closely resemble the corresponding human disease and it is considered a well-established spontaneous animal model to study OS biology. The purpose of this study was to investigate miRNA dysregulation in canine OS.

Methods

We evaluated miRNA expression in primary canine OS tumors and normal canine osteoblast cells using the nanoString nCounter system. Quantitative PCR was used to validate the nanoString findings and to assess miR-9 expression in canine OS tumors, OS cell lines, and normal osteoblasts. Canine osteoblasts and OS cell lines were stably transduced with pre-miR-9 or anti-miR-9 lentiviral constructs to determine the consequences of miR-9 on cell proliferation, apoptosis, invasion and migration. Proteomic and gene expression profiling of normal canine osteoblasts with enforced miR-9 expression was performed using 2D-DIGE/tandem mass spectrometry and RNA sequencing and changes in protein and mRNA expression were validated with Western blotting and quantitative PCR. OS cell lines were transduced with gelsolin (GSN) shRNAs to investigate the impact of GSN knockdown on OS cell invasion.

Results

We identified a unique miRNA signature associated with primary canine OS and identified miR-9 as being significantly overexpressed in canine OS tumors and cell lines compared to normal osteoblasts. Additionally, high miR-9 expression was demonstrated in tumor-specific tissue obtained from primary OS tumors. In normal osteoblasts and OS cell lines transduced with miR-9 lentivirus, enhanced invasion and migration were observed, but miR-9 did not affect cell proliferation or apoptosis. Proteomic and transcriptional profiling of normal canine osteoblasts overexpressing miR-9 identified alterations in numerous genes, including upregulation of GSN, an actin filament-severing protein involved in cytoskeletal remodeling. Lastly, stable downregulation of miR-9 in OS cell lines reduced GSN expression with a concomitant decrease in cell invasion and migration; concordantly, cells transduced with GSN shRNA demonstrated decreased invasive properties.

Conclusions

Our findings demonstrate that miR-9 promotes a metastatic phenotype in normal canine osteoblasts and malignant OS cell lines, and that this is mediated in part by enhanced GSN expression. As such, miR-9 represents a novel target for therapeutic intervention in OS.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2837-5) contains supplementary material, which is available to authorized users.

Aberrant expression of miR-9 in benign and malignant breast tumors

PURPOSE

MicroRNAs (miRNAs) are involved in the progression of breast cancer (BC). miR-9 has been reported to be correlated with either favorable or unfavorable events in BC. This study was aimed to evaluate the expression level of miR-9 in human breast tissues, including benign and malignant tumor samples and also healthy tissue.

MATERIALS AND METHODS

The expression level of miR-9 was analyzed in 10 normal breast tissues, 30 malignant, and 30 benign breast tumor tissue samples using RT-PCR and qPCR. In addition, bioinformatics assessment upon miR-9 functionality in BC cells was performed.

RESULTS AND DISCUSSION

The miR-9 expression level was downregulated in tumor tissues, including benign and malignant compared to the healthy tissue was observed (P value, < 0.0001; fold change, -1.37). In addition, miR-9 expression level was reduced in benign tumors compared with malignant tumors (P value, < 0.0001; fold change, -1.35). Moreover, according to the AUCs (area under curve) of receiver operating characteristic (ROC) curves, miR-9 showed significant capability for distinguishing benign from healthy, malignant from healthy, benign from malignant, and tumor from health tissues. Furthermore, pathways in cancer, p53 signaling pathway, and focal adhesion were manifested by computational analysis as miR-9 related signaling pathways which have logical association with experimental observations.

CONCLUSION

In conclusion, downregulation of miR-9 in benign tumors vs healthy tissue and its overexpression in malignant tumors vs benign tumors suggest paradoxical functionality for this miRNA. Our results shed additional information on controversial expression pattern of miR-9 depending on different progression level of BC.

Role of miRNA-9 in Brain Development

MicroRNAs (miRNAs) are a class of small regulatory RNAs involved in gene regulation. The regulation is effected by either translational inhibition or transcriptional silencing. In vertebrates, the importance of miRNA in development was discovered from mice and zebrafish dicer knockouts. The miRNA-9 (miR-9) is one of the most highly expressed miRNAs in the early and adult vertebrate brain. It has diverse functions within the developing vertebrate brain. In this article, the role of miR-9 in the developing forebrain (telencephalon and diencephalon), midbrain, hindbrain, and spinal cord of vertebrate species is highlighted. In the forebrain, miR-9 is necessary for the proper development of dorsoventral telencephalon by targeting marker genes expressed in the telencephalon. It regulates proliferation in telencephalon by regulating Foxg1, Pax6, Gsh2, and Meis2 genes. The feedback loop regulation between miR-9 and Nr2e1/Tlx helps in neuronal migration and differentiation. Targeting Foxp1 and Foxp2, and Map1b by miR-9 regulates the radial migration of neurons and axonal development. In the organizers, miR-9 is inversely regulated by hairy1 and Fgf8 to maintain zona limitans interthalamica and midbrain–hindbrain boundary (MHB). It maintains the MHB by inhibiting Fgf signaling genes and is involved in the neurogenesis of the midbrain–hindbrain by regulating Her genes. In the hindbrain, miR-9 modulates progenitor proliferation and differentiation by regulating Her genes and Elav3. In the spinal cord, miR-9 modulates the regulation of Foxp1 and Onecut1 for motor neuron development. In the forebrain, midbrain, and hindbrain, miR-9 is necessary for proper neuronal progenitor maintenance, neurogenesis, and differentiation. In vertebrate brain development, miR-9 is involved in regulating several region-specific genes in a spatiotemporal pattern.

Long noncoding RNA ZNFX1-AS1 suppresses growth of hepatocellular carcinoma cells by regulating the methylation of miR-9

Many long noncoding RNAs have been reported to play pivotal roles in cancer biology. Among them, the long noncoding RNA ZNFX1-AS1 has been confirmed to function in breast cancer progression, but the role of ZNFX1-AS1 in hepatocellular carcinoma (HCC) growth and the related molecular mechanisms still remains unknown. In the present study, we first identified the expression of ZNFX1-AS1 in HCC patients' specimens and HCC cell lines through quantitative reverse transcription polymerase chain reaction. Next, the effects of ZNFX1-AS1 on HCC cell growth and apoptosis were analyzed. MTT assay was used to measure the cell numbers, and fluorescence-activated cell sorting analysis was performed to evaluate cell apoptosis. Finally, the relationship between ZNFX1-AS1 and miR-9 in HCC was studied. Our results suggest that ZNFX1-AS1 was markedly downregulated in HCC samples and cell lines. Overexpression of ZNFX1-AS1 inhibited the cell proliferation and colony formation in HCC cell lines and also induced HCC cell apoptosis. Additionally, miR-9 was lowly expressed in HCC tissues and positively correlated with ZNFX1-AS1 expression. Meanwhile, significant upregulation of miR-9 and downregulation of the methylation of miR-9 promoter CpG island were observed when ZNFX1-AS1 was overexpressed. In summary, our results indicate that ZNFX1-AS1 plays a vital role in HCC progression via regulating the methylation of miR-9 and may be a potential tumor suppressor.

Neuroprotective Effect of Osthole on Neuron Synapses in an Alzheimer's Disease Cell Model via Upregulation of MicroRNA-9

Accumulation of β-amyloid peptide (Aβ) in the brain plays an important role in the pathogenesis of Alzheimer's disease (AD). It has been reported that osthole exerts its neuroprotective effect on neuronal synapses, but its exact mechanism is obscure. Recently, microRNAs have been demonstrated to play a crucial role in inducing synaptotoxicity by Aβ, implying that targeting microRNAs could be a therapeutic approach of AD. In the present study, we investigated the neuroprotective effects of osthole on a cell model of AD by transducing APP695 Swedish mutant (APP695swe, APP) into mouse cortical neurons and human SH-SY5Y cells. In this study, the cell counting kit CCK-8, apoptosis assay, immunofluorescence analysis, enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction, and Western blot assay were used. We found that osthole could enhance cell viability, prevent cell death, and reverse the reduction of synaptic proteins (synapsin-1, synaptophysin, and postsynaptic density-95) in APP-overexpressed cells, which was attributed to increases in microRNA-9 (miR-9) expression and subsequent decreases in CAMKK2 and p-AMPKα expressions. These results demonstrated that osthole plays a neuroprotective activity role in part through upregulating miR-9 in AD.

Modulation of influenza A virus replication by microRNA-9 through targeting MCPIP1

MicroRNAs (miRNAs), a family of small non-coding RNAs controlling translation and transcription of its target genes, play important roles in the regulation of various biological processes, including viral infection. Influenza A viruses (IAV) infection alters expression of cellular miRNAs, which in turn can modify the cellular environment to facilitate efficient virus replication. In this study, we showed that IAV infection significantly induced miR-9 expression in A549 cells, which occurred earlier than drastic expression of viral matrix (M) and nucleoprotein (NP) genes. Overexpression of miR-9 enhanced viral gene expression and production of infectious progeny, while knockdown of miR-9 significantly inhibited IAV replication in A549 cells. Recent studies have revealed antiviral potential of monocyte chemoattractant protein 1-induced protein 1 (MCPIP1), a PIN-like RNase capable of targeting and degrading viral RNA. Subsequently, we comprehensively confirmed that MCPIP1 functionally inhibited viral M and NP genes expression and progeny production, and also was regulated by miR-9 in A549 cells. Furthermore, MCPIP1 overexpression abrogated miR-9-induced IAV replication. Taken together, our findings indicate a new role of miR-9 induction in IAV infection and suggest IAV may hijack cellular miR-9 to benefit the viral life cycle. J. Med. Virol. 89:41-48, 2017. © 2016 Wiley Periodicals, Inc.

MicroRNAs Are Involved in the Development of Morphine-Induced Analgesic Tolerance and Regulate Functionally Relevant Changes in Serpini1

Long-term opioid treatment results in reduced therapeutic efficacy and in turn leads to an increase in the dose required to produce equivalent pain relief and alleviate break-through or insurmountable pain. Altered gene expression is a likely means for inducing long-term neuroadaptations responsible for tolerance. Studies conducted by our laboratory (Tapocik et al., 2009) revealed a network of gene expression changes occurring in canonical pathways involved in neuroplasticity, and uncovered miRNA processing as a potential mechanism. In particular, the mRNA coding the protein responsible for processing miRNAs, Dicer1, was positively correlated with the development of analgesic tolerance. The purpose of the present study was to test the hypothesis that miRNAs play a significant role in the development of analgesic tolerance as measured by thermal nociception. Dicer1 knockdown, miRNA profiling, bioinformatics, and confirmation of high value targets were used to test the proposition. Regionally targeted Dicer1 knockdown (via shRNA) had the anticipated consequence of eliminating the development of tolerance in C57BL/6J (B6) mice, thus supporting the involvement of miRNAs in the development of tolerance. MiRNA expression profiling identified a core set of chronic morphine-regulated miRNAs (miR's 27a, 9, 483, 505, 146b, 202). Bioinformatics approaches were implemented to identify and prioritize their predicted target mRNAs. We focused our attention on miR27a and its predicted target serpin peptidase inhibitor clade I (Serpini1) mRNA, a transcript known to be intricately involved in dendritic spine density regulation in a manner consistent with chronic morphine's consequences and previously found to be correlated with the development of analgesic tolerance. In vitro reporter assay confirmed the targeting of the Serpini1 3'-untranslated region by miR27a. Interestingly miR27a was found to positively regulate Serpini1 mRNA and protein levels in multiple neuronal cell lines. Lastly, Serpini1 knockout mice developed analgesic tolerance at a slower rate than wild-type mice thus confirming a role for the protein in analgesic tolerance. Overall, these results provide evidence to support a specific role for miR27a and Serpini1 in the behavioral response to chronic opioid administration (COA) and suggest that miRNA expression and mRNA targeting may underlie the neuroadaptations that mediate tolerance to the analgesic effects of morphine.

miR-9 Mediates CALHM1-Activated ATP-P2X7R Signal in Painful Diabetic Neuropathy Rats

In this study, we planned to illuminate the mechanisms of the expression and function of CALHM1 in painful diabetic neuropathy (PDN). PDN rat model was constructed. The expression of CALHM1 and miR-9 in rat spinal dorsal horn neurons was detected. The correlation between the level of CALHM1 mRNA and 50 % PWT and the relationship between the expression of CALHM1 and miR-9 in rat spinal dorsal horn neurons were statistically analyzed. The effect of miR-9 and CALHM1 on each other's expression in PDN rat spinal dorsal horn neurons were tested by qRT-PCR or Western blot. The co-culture system of neurons and glias from PDN rat spinal dorsal horn was constructed. The concentration of calcium and ATP as well as the expression of P2X7 receptor regulated by CALHM1 and miR-9 in PDN rat spinal dorsal horn neurons was measured. The results showed that the expression of CALHM1 was increased in PDN rat compared with controls, while its mRNA level was negatively correlated with 50 % PWT. miR-9, which was also upregulated in the spinal dorsal horn neurons of PDN rats, was positively correlated with the expression of CALHM1. The concentration of calcium and ATP as well as the expression of P2X7 receptor in glias was also increased in PDN rats. These increases could be reverted by inhibiting CALHM1 and/or miR-9. CALHM1 is involved in miR-9-mediated ATP-P2X7 pathway between neurons and glias in PDN rat.