Expression of two parental imprinted miRNAs improves the risk stratification of neuroblastoma patients

Oncogenic role of MIR516A in human bladder cancer was mediated by its attenuating PHLPP2 expression and BECN1-dependent autophagy

Although MIR516A has been reported to be downregulated and act as a tumor suppressor in multiple cancers, its expression and potential contribution to human bladder cancer (BC) remain unexplored. Unexpectedly, we showed here that MIR516A was markedly upregulated in human BC tissues and cell lines, while inhibition of MIR516A expression attenuated BC cell monolayer growth in vitro and xenograft tumor growth in vivo, accompanied with increased expression of PHLPP2. Further studies showed that MIR516A was able to directly bind to the 3'-untranslated region of PHLPP2 mRNA, which was essential for its attenuating PHLPP2 expression. The knockdown of PHLPP2 expression in MIR516A-inhibited cells could reverse BC cell growth, suggesting that PHLPP2 is a MIR516A downstream mediator responsible for MIR516A oncogenic effect. PHLPP2 was able to mediate BECN1/Beclin1 stabilization indirectly, therefore promoting BECN1-dependent macroautophagy/autophagy, and inhibiting BC tumor cell growth. In addition, our results indicated that the increased autophagy by attenuating MIR516A resulted in a dramatic inhibition of xenograft tumor formation in vivo. Collectively, our results reveal that MIR516A has a novel oncogenic function in BC growth by directing binding to PHLPP2 3'-UTR and inhibiting PHLPP2 expression, in turn at least partly promoting CUL4A-mediated BECN1 protein degradation, thereby attenuating autophagy and promoting BC growth, which is a distinct function of MIR516A identified in other cancers.Abbreviation: ATG3: autophagy related 3; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG12: autophagy related 12; BAF: bafilomycin A1; BC: bladder cancer; CHX: cycloheximide; Co-IP: co-immunoprecipitation; CUL3: cullin 3; CUL4A: cullin 4A; CUL4B: cullin 4B; IF: immunofluorescence: IHC-p: immunohistochemistry-paraffin; MIR516A: microRNA 516a (microRNA 516a1 and microRNA 516a2); MS: mass spectrometry; PHLPP2: PH domain and leucine rich repeat protein phosphatase.

MiRNA-516a promotes bladder cancer metastasis by inhibiting MMP9 protein degradation via the AKT/FOXO3A/SMURF1 axis

BACKGROUND

Metastasis is the leading cause of death in patients with bladder cancer (BC). However, current available treatments exert little effects on metastatic BC. Moreover, traditional grading and staging have only a limited ability to identify metastatic BC. Accumulating evidence indicates that the aberrant expression of microRNA is intimately associated with tumor progression. So far, many miRNAs have been identified as molecular targets for cancer diagnosis and therapy. This study focused on the role of miR-516a-5p (miR-516a) in BC.

METHODS

MiR-516a expression and its downstream signaling pathway were detected using molecular cell biology and biochemistry approaches and techniques. Fresh clinical BC tissue was used to study the clinicopathological characteristics of patients with different miR-516a expression. The biological functions of miR-516a in BC were tested both in vivo and in vitro.

RESULTS

A more invasive BC phenotype was significantly and positively correlated with miR-516a overexpression in BC patients. MiR-516a inhibition significantly decreased BC cell invasion and migration in vitro and in vivo. Furthermore, miR-516a attenuated the expression of PH domain leucine-rich repeat-containing protein phosphatase 2 protein and inhibited SMAD-specific E3 ubiquitin protein ligase 1 transcription by activating the AKT/Forkhead box O3 signaling pathway, which stabilized MMP9 and slowed down its proteasomal degradation, ultimately promoting BC motility and invasiveness.

CONCLUSIONS

Our findings reveal the crucial function of miR-516a in promoting BC metastasis, and elucidate the molecular mechanism involved, suggesting that miR-516a may be a promising novel diagnostic and therapeutic target for BC.

MicroRNA dysregulation interplay with childhood abdominal tumors

Abdominal tumors (AT) in children account for approximately 17% of all pediatric solid tumor cases, and frequently exhibit embryonal histological features that differentiate them from adult cancers. Current molecular approaches have greatly improved the understanding of the distinctive pathology of each tumor type and enabled the characterization of novel tumor biomarkers. As seen in abdominal adult tumors, microRNAs (miRNAs) have been increasingly implicated in either the initiation or progression of childhood cancer. Moreover, besides predicting patient prognosis, they represent valuable diagnostic tools that may also assist the surveillance of tumor behavior and treatment response, as well as the identification of the primary metastatic sites. Thus, the present study was undertaken to compile up-to-date information regarding the role of dysregulated miRNAs in the most common histological variants of AT, including neuroblastoma, nephroblastoma, hepatoblastoma, hepatocarcinoma, and adrenal tumors. Additionally, the clinical implications of dysregulated miRNAs as potential diagnostic tools or indicators of prognosis were evaluated.

miR-15a-5p, miR-15b-5p, and miR-16-5p inhibit tumor progression by directly targeting MYCN in neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid malignancy in children. Despite current aggressive treatment regimens, the prognosis for high-risk NB patients remains poor, with the survival of less than 40%. Amplification/stabilization of MYCN oncogene, in NB is associated with a high risk of recurrence. Thus, there is an urgent need for novel therapeutics. The deregulated expression of microRNA (miR) is reported in NB; nonetheless, its effect on MYCN regulation is poorly understood. First, we identified that miR-15a-5p, miR-15b-5p, and miR-16-5p (hereafter miR-15a, miR-15b or miR-16) were down-regulated in patient-derived xenografts (PDX) with high MYCN expression. MiR targeting sequences on MYCN mRNA were predicted using online databases such as TargetScan and miR database. The R2 database, containing 105 NB patients, showed an inverse correlation between MYCN mRNA and deleted in lymphocytic leukemia (DLEU) 2, a host gene of miR-15. Moreover, overexpression of miR-15a, miR-15b or miR-16 significantly reduced the levels of MYCN mRNA and N-Myc protein. Conversely, inhibiting miR dramatically enhanced MYCN mRNA and N-Myc protein levels, as well as increasing mRNA half-life in NB cells. By performing immunoprecipitation assays of argonaute-2 (Ago2), a core component of the RNA-induced silencing complex, we showed that miR-15a, miR-15b and miR-16 interact with MYCN mRNA. Luciferase reporter assays showed that miR-15a, miR-15b and miR-16 bind with 3'UTR of MYCN mRNA, resulting in MYCN suppression. Moreover, induced expression of miR-15a, miR-15b and miR-16 significantly reduced the proliferation, migration, and invasion of NB cells. Finally, transplanting miR-15a-, miR-15b- and miR-16-expressing NB cells into NSG mice repressed tumor formation and MYCN expression. These data suggest that miR-15a, miR-15b and miR-16 exert a tumor-suppressive function in NB by targeting MYCN. Therefore, these miRs could be considered as potential targets for NB treatment.

MiR-516a-5p inhibits the proliferation of non-small cell lung cancer by targeting HIST3H2A

The dysregulation of microRNAs (miRNAs) is associated with the pathogenesis of non-small cell lung cancer (NSCLC). However, the mechanisms by which miR-516a-5p contributes to NSCLC remain unclear. The association between miR-516a-5p expression and the clinicopathological characteristics and prognosis in patients with NSCLC was analyzed by The Cancer Genome Atlas (TCGA) data set. The targets of miR-516a-5p were identified by bioinformatic analysis and luciferase report assay. MTT and soft agar assays were conducted to investigate the function of miR-516a-5p in NSCLC cells. We found that the expression of miR-516a-5p was decreased in NSCLC tissues and associated with the age, pathological stage, and tumor size, acting as an independent prognostic factor of tumor recurrence in patients with NSCLC. Restoration of miR-516a-5p inhibited the cell viability and anchorage-independent growth of NSCLC cells, but its inhibitor had the opposite effects. Histone cluster 3 H2A (HIST3H2A) was further identified as a direct target of miR-516a-5p and displayed a negative correlation with miR-516a-5p expression in NSCLC tissues. Overexpression of HIST3H2A reversed the anti-proliferation effects induced by miR-516a-5p and acted as an independent prognostic factor of poor survival in patients with NSCLC. Altogether, our findings demonstrate that miR-516a-5p may function as a tumor suppressive factor in NSCLC cells by targeting HIST3H2A and might represent a potential indicator of tumor recurrence in patients with NSCLC.

A novel six-microRNA-based model to improve prognosis prediction of breast cancer

Current tumor-node-metastasis (TNM) stage is unable to accurately predict the overall survival (OS) in breast cancer (BC) patients. This study aimed to construct a microRNA (miRNA)-based model to improve survival prediction of BC. We confirmed 99 differentially expressed miRNAs (DEMs) in 1044 BC samples compared to 102 adjacent normal breast tissues from The Cancer Genome Atlas (TCGA) database. Prognostic DEMs were used to establish a miRNA-based nomogram via Cox regression model. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analyses (KEGG) were executed to analyze target genes of miRNAs. A six-miRNA signature was screened to effectively distinguish high-risk patients in the primary and validation cohort (all P<0.001). Furthermore, we established a novel prognostic model incorporating the six-miRNA signature and clinical risk factors to predict 5-year OS of BC. Time-dependent receiver operating characteristic analysis suggested that the predictive accuracy of the six-miRNA-based nomogram was distinctly higher than that of TNM stage (0.758 vs 0.650, P<0.001). GO and KEGG pathway analyses showed that the 39 target genes mainly enrichment in protein binding, cytoplasm and MAPK signaling pathway. Our six-miRNA-based model is a reliable prognostic tool for survival prediction and provides information for individualized treatment decisions in BC patients.

Non-High-Risk Neuroblastoma: Classification and Achievements in Therapy

Neuroblastoma, a tumor of the sympathetic nervous system, is the most common extra-cranial neoplasm of childhood. Variables with prognostic significance in patients with neuroblastoma, including age at diagnosis, disease stage, tumor histology, MYCN gene amplification, tumor cell ploidy, and the presence of segmental chromosomal aberrations are utilized to classify patients based on risk of disease recurrence. Patients with non-high-risk neuroblastoma, low- and intermediate-risk categories, represent nearly half of all newly diagnosed cases. This group has an excellent event-free and overall survival with current therapy. Over time, the objective in treatment of non-high-risk neuroblastoma has been reduction of therapy intensity to minimize short- and long-term adverse events all the while maintaining excellent outcomes.

Integrative analysis of dysregulated microRNAs and mRNAs in multiple recurrent synchronized renal tumors from patients with von Hippel-Lindau disease

Von Hippel-Lindau (VHL) disease is a rare auto-somal dominant syndrome that is the main cause of inherited clear-cell renal cell carcinoma (ccRCC), which generally occurs in the form of multiple recurrent synchronized tumors. Affected patients are carriers of a germline mutation in the VHL tumor suppressor gene. Somatic mutations of this gene are also found in sporadic ccRCC and numerous pan-genomic studies have reported a dysregulation of microRNA (miRNA) expression in these sporadic tumors. In order to investigate the molecular mechanisms underlying the pathogenesis of VHL-associated ccRCC, particularly in the context of multiple tumors, the present study characterized the mRNA and miRNA transcriptome through an integrative analysis compared with sporadic renal tumors. In the present study, two series of ccRCC samples were used. The first set consisted of several samples from different tumors occurring in the same patient, for two independent patients affected with VHL disease. The second set consisted of 12 VHL-associated tumors and 22 sporadic ccRCC tumors compared with a pool of normal renal tissue. For each sample series, an expression analysis of miRNAs and mRNAs was conducted using microarrays. The results indicated that multiple tumors within the kidney of a patient with VHL disease featured a similar pattern of miRNA and gene expression. In addition, the expression levels of miRNA were able to distinguish VHL-associated tumors from sporadic ccRCC, and it was identified that 103 miRNAs and 2,474 genes were differentially expressed in the ccRCC series compared with in normal renal tissue. The majority of dysregulated genes were implicated in 'immunity' and 'metabolism' pathways. Taken together, these results allow a better understanding of the occurrence of ccRCC in patients with VHL disease, by providing insights into dysregulated miRNA and mRNA. In the set of patients with VHL disease, there were few differences in miRNA and mRNA expression, thus indicating a similar molecular evolution of these synchronous tumors and suggesting that the same molecular mechanisms underlie the pathogenesis of these hereditary tumors.

Abdominal Aortic Aneurysm-Associated MicroRNA-516a-5p Regulates Expressions of Methylenetetrahydrofolate Reductase, Matrix Metalloproteinase-2, and Tissue Inhibitor of Matrix Metalloproteinase-1 in Human Abdominal Aortic Vascular Smooth Muscle Cells

BACKGROUND

MicroRNAs (miRNAs or miRs) have been highlighted to be involved in abdominal aortic aneurysm (AAA) with the emergence of recent miRNA microarray profiling studies. miR-516a-5p has been shown to be significantly overexpressed in vascular smooth muscle cells (VSMCs) from human AAA tissues from our previous microarray study, suggesting its crucial association with AAA. In addition, further bioinformatics analysis predicted methylenetetrahydrofolate reductase (MTHFR), which regulates homocysteine (Hcy) metabolism and is proposed to be a risk gene for AAA formation and to be the downregulation target of miR-516a-5p. However, the pathogenic role of miR-516a-5p in VSMCs for AAA formation remains unresolved. This study aims to investigate the role of miR-516a-5p in human VSMCs for AAA pathogenesis.

METHODS

miR-516a-5p was stably overexpressed and knocked down in VSMCs explant cultured from human abdominal aortic tissues by means of lentiviral system. The MTHFR protein expression was first examined by Western blotting. In addition, the protein expressions of several key components involved in AAA pathogenic features are as follows: matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitor of matrix metalloproteinase (TIMP)-1 and TIMP-2 for elastin degradation; collagen type 1 alpha 1 for compensatory collagen synthesis; monocyte chemoattractant protein-1 for inflammation, were also evaluated. Apoptotic level of VSMCs was examined by terminal deoxynucleotidyl transferase dUTP nick end labeling assay.

RESULTS

Results showed that protein expression of MTHFR was significantly downregulated on miR-516a-5p overexpression (P < 0.05) in VSMCs, whereas it was significantly upregulated on miR-516a-5p knockdown (P < 0.05). Of all the AAA key components investigated, only MMP-2 and TIMP-1 protein expressions were found altered. A significant increase in MMP-2 (P < 0.05) and decrease in TIMP-1 (P < 0.05) expressions were observed on miR-516a-5p overexpression in VSMCs. Apoptosis was not promoted on miR-516a-5p overexpression or knockdown in VSMCs.

CONCLUSIONS

Our findings suggested that miR-516a-5p may regulate MTHFR, MMP-2, and TIMP-1 expressions in human VSMCs, possibly promoting the disruption of Hcy metabolism and proteolytic degradation of elastin for AAA formation.

MicroRNA profiling of low-grade glial and glioneuronal tumors shows an independent role for cluster 14q32.31 member miR-487b

Low-grade (WHO I-II) gliomas and glioneuronal tumors represent the most frequent primary tumors of the central nervous system in children. They often have a good prognosis following total resection, however they can create many neurological complications due to mass effect, and may be difficult to resect depending on anatomic location. MicroRNAs have been identified as molecular regulators of protein expression/translation that can repress multiple mRNAs concurrently through base pairing, and have an important role in cancer, including brain tumors. Using the NanoString digital counting system, we analyzed the expression levels of 800 microRNAs in nine low-grade glial and glioneuronal tumor types (n=45). A set of 61 of these microRNAs were differentially expressed in tumors compared with the brain, and several showed levels varying by tumor type. The expression differences were more accentuated in subependymal giant cell astrocytoma, compared with other groups, and demonstrated the highest degree of microRNA repression validated by RT-PCR, including miR-129-2-3p, miR-219-5p, miR-338-3p, miR-487b, miR-885-5p, and miR-323a-3p. Conversely, miR-4488 and miR-1246 were overexpressed in dysembryoplastic neuroepithelial tumors compared with the brain and other tumors. The cluster 14q32.31 member miR-487b was variably under-expressed in pediatric glioma lines compared with human neural stem cells. Overexpression of miR-487b in a pediatric glioma cell line (KNS42) using lentiviral vectors led to a decrease in colony formation in soft agar (30%) (P<0.05), and decreased expression of known predicted targets PROM1 and Nestin (but not WNT5A). miR-487b overexpression had no significant effect on cell growth, proliferation, sensitivity to temozolomide, migration, or invasion. In summary, microRNA regulation appears to have a role in the biology of glial and glioneuronal tumor subtypes, a finding that deserves further investigation.

miR-487b, miR-3963 and miR-6412 delay myogenic differentiation in mouse myoblast-derived C2C12 cells

Background

Skeletal muscle differentiation is a multistep, complex pathway in which several important signaling molecules are involved. Recently, microRNAs (miRNAs), endogenous non-coding small RNAs that regulate mRNAs, have been proposed to be involved in skeletal muscle differentiation. In this study, we identified skeletal muscle differentiation-associated miRNAs by comparing miRNA expression profiles between C2C12 cells and Wnt4 over-expressing C2C12 cells (W4-08), which can spontaneously differentiate into myotubes.

Results

We identified miR-206, miR-133a, and miR-133b as up-regulated miRNAs and miR-487b, miR-3963 and miR-6412 as down-regulated miRNAs in differentiating cells. We focused on the down-regulated miRNAs because their functions were largely unknown. Transfection of mimics of these miRNAs into C2C12 cells resulted in significantly reduced expression of myogenic differentiation markers, including troponin T and myosin heavy chain fast type and slow type, but did not affect the expression of the myogenic transcription factors, MyoD and myogenin.

Conclusions

These miRNAs were characterized as new myogenic differentiation-associated miRNAs which may delay late myogenic differentiation or maturation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12860-015-0061-9) contains supplementary material, which is available to authorized users.