MicroRNA miR-93 promotes tumor growth and angiogenesis by targeting integrin-β8

The role of microRNA-93 regulating angiopoietin2 in the formation of malignant pleural effusion

The biological roles of miRNAs in the development of malignant pleural effusion (MPE) are unclear. In this study, the miRNA microarray analysis was performed in two different prognosis groups of lung adenocarcinoma patients. Expression profiles of miRNAs in MPEs were identified. With the help of quantification PCR, we confirmed the expression differences of miRNAs and further analyzed their biological functions and relative target genes in vitro. The target gene of miR-93 was estimated by online database, and also, the protein was tested. The target gene and the binding sites of specific miRNA were estimated by online database. The combining capacity of binding sites was verified by luciferase reporter gene assay, and the target gene protein was tested by western blot. We detected 107 miRNAs with expression differences (n = 10) and confirmed significant expression differences in miR-93 and miR-146a in two groups of patients (n = 84). By manipulating miR-93 expression of human lymphatic endothelial cells (HLEC) and human umbilical vein endothelial cells (HUVEC), we discovered that high expression of miR-93 inhibited migration, proliferation, and angiogenesis. And also, miR-93 increased not only apoptosis, but also G1 phase cell block. By using luciferase reporter gene assay and western blot, we confirmed that angiopoietin2 (Ang2) was the target of miR-93. The data showed that miR-93 has an inhibiting effect on pleural effusion. By targeting Ang2, miR-93 regulates angiogenesis and lymphangiogenesis and plays a role in pathogenetic mechanism of MPE. MiR-93/Ang2 may shed light on potential new targets in cancer treatment.

Plasma level of miR-93 is associated with higher risk to develop type 2 diabetic retinopathy

PURPOSE

MicroRNA-93 (miR-93) usually acts as a promoter of tumor progression in several human carcinomas. It has been found distinctly high in eyes with proliferative diabetic retinopathy (DR). The present study aims to investigate the role of plasma miR-93 in the progression of type 2 diabetic retinopathy (T2DR).

METHODS

Our study subjects were made up of 140 type 2 diabetes mellitus (T2DM) patients who were assigned into DR (DR patients, n = 75), NDR (non-DR patients, n = 65), and control (healthy individuals, n = 127) groups. Levels of fasting blood glucose (FBG), fasting plasma glucose (FPG), triglyceride (TG), glycosylated hemoglobin (HbA1c), total cholesterol (TC), blood urea nitrogen (BUN), creatinine (Cr), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and fasting insulin (FIsn) were detected by automatic biochemical analyzer. Enzyme-linked immunosorbent assay (ELISA) was performed for the levels of interleukin (IL)-1, IL-6, tumor necrosis factor (TNF)-α and vascular endothelial growth factor (VEGF), qRT-PCR for the miR-93 expression in plasma, and mRNA expressions of IL-1, IL-6, TNF-α and VEGF; receiver operating characteristic (ROC) curve for the diagnostic performance of miR-93 to T2DR, Pearson correlation analysis for correlation analysis between miR-93 and other indexes detected before and multivariate logistic regression analyses for the risk factors for T2DR.

RESULTS

The DR and NDR groups exhibited elevated course of disease, and decreased levels of FBG, FPG, TG, HbA1c, TC, BUN, Cr, HDL-C, FIsn, IL-1, IL-6, TNF-α and VEGF but declined LDL-C level as compared to the control group. The course of disease was longer and the levels of FBG, FPG, HbA1c, IL1, IL6 and VEGF were higher in the DR group than those in the NDR group (all P < 0.05). The miR-93 expression and RNA expressions of IL-1, IL-6, TNF-α and VEGF were higher in the DR group than those in the NDR group (P < 0.05). The best cutoff for miR-93 to assess T2DR was 1.31, with a Youden index of 0.63, sensitivity of 73.33%, specificity of 89.24%, and area under the curve (AUC) of 0.866. Pearson correlation analysis indicated that miR-93 expression was positively associated with course of disease, the levels of FPG, HbA1c, TNF-α and VEGF. T2DM patients with longer disease course, higher levels of FBG, HbA1c, VEGF and miR-93 expression were risk factors for developing DR.

CONCLUSION

Our study demonstrates that plasma miR-93 is associated with the progression of T2DR and it can sever as a diagnostic marker for T2DR.

Evaluation Expression of Microrna-93 and Integrin Β8 in Different Types of Glioma Tumors

MicroRNAs (miRNAs), are a type of small non-coding RNAs, that induce mRNA degradation or repress translation by binding to the 3′-untranslated region (UTR) of its target mRNA. Some specific miRNAs, e.g. miR-93, have been discovered to be involved in pathological procedures by targeting some oncogenes or tumor suppressors in glioma. In the present study, real-time RT-PCR data was indicated the expression pattern and prognostic value of miR-93 in patients with types of Glioma. MiR-93 expression was significantly decreased in tumor tissue compared with normal group brain tissues (P<0.001). Low miR-93 expression was significantly correlated with progressive tumor grade (P=0.02). Moreover, multivariate analysis showed that miR-93 decreased expression (HR, 4.3; 95% CI, 0.8–17.2, P=0.02), advanced tumor grade (HR, 3.1; 95% CI, 0.2–13.9, P=0.04), for integrinβ8, level expression was inverse. Our data was shown that the down regulation of miR-93 was significantly correlated with unfavorable pathological features in patients with Glioma. Suggesting that decreased expression of miR-93can be used as a novel prognostic factor for this disease.

A Comprehensive Review of Genomics and Noncoding RNA in Gliomas

Glioblastoma (GBM) is the most malignant primary adult brain tumor. In spite of our greater understanding of the biology of GBMs, clinical outcome of GBM patients remains poor, as their median survival with best available treatment is 12 to 18 months. Recent efforts of The Cancer Genome Atlas (TCGA) have subgrouped patients into 4 molecular/transcriptional subgroups: proneural, neural, classical, and mesenchymal. Continuing efforts are underway to provide a comprehensive map of the heterogeneous makeup of GBM to include noncoding transcripts, genetic mutations, and their associations to clinical outcome. In this review, we introduce key molecular events (genetic and epigenetic) that have been deemed most relevant as per studies such as TCGA, with a specific focus on noncoding RNAs such as microRNAs (miRNA) and long noncoding RNAs (lncRNA). One of our main objectives is to illustrate how miRNAs and lncRNAs play a pivotal role in brain tumor biology to define tumor heterogeneity at molecular and cellular levels. Ultimately, we elaborate how radiogenomics-based predictive models can describe miRNA/lncRNA-driven networks to better define heterogeneity of GBM with clinical relevance.

Synthetic miR-145 Mimic Enhances the Cytotoxic Effect of the Antiangiogenic Drug Sunitinib in Glioblastoma

Although aggressive therapeutic regimen has been applied in the treatment of Glioblastoma (GBM), the prognosis of patients with GBM remains poor. Preclinical studies have demonstrated the efficacy of Suntinib in GBM both in vitro and in vivo. In this study, we showed that the cytotoxicity was enhanced by transfection with miR-145 mimic. In addition, we suggested that the enhanced cytotoxicity of Sunitinib by miR-145 mimic was mediated by inhibition of both P-gp and Bcrp.

Bioinformatic analysis of microRNA and mRNA Regulation in peripheral blood mononuclear cells of patients with chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a progressive, irreversible chronic inflammatory disorder typified by increased recruitment of monocytes, lymphocytes and neutrophils. Because of this, as well as the convenience of peripheral blood nuclear cells (PBMCs) assessments, miRNA profiling of PBMCs has drawn increasing attention in recent years for various disease. Therefore, we analyzed miRNA and mRNA profiles to understand their regulatory network between COPD subjects versus smokers without airflow limitation.

METHODS

miRNA and mRNA profiling of PBMCs from pooled 17 smokers and 14 COPD subjects was detected by high-throughput microarray. The expression of dysregulated miRNAs were validated by q-PCR. The miRNA targets in dysregulated mRNAs were predicted and the pathway enrichment was analyzed.

RESULTS

miRNA microarray showed that 8 miRNAs were up-regulated and 3 miRNAs were down-regulated in COPD subjects compared with smokers; the upregulation of miR-24-3p, miR-93-5p, miR-320a and miR-320b and the downregulation of miR-1273 g-3p were then validated. Bioinformatic analysis of regulatory network between miRNA and mRNA showed that NOD and TLR were the most enriched pathways. miR-24-3p was predicted to regulate IL-18, IL-1β, TNF, CCL3 and CCL4 and miR-93-5p to regulate IκBα.

CONCLUSIONS

The expression of miRNA and mRNA were dysregulated in PBMCs of COPD patients compared with smokers without airflow limitation. The regulation network between the dysregulated miRNA and mRNA may provide potential therapeutic targets for COPD.

Profiling of microRNAs in AML cells following overexpression or silencing of the VEGF gene

Acute myeloid leukemia (AML) is a disease of the hematopoietic progenitor cells associated with heterogeneous clonal proliferation. Vascular endothelial growth factor (VEGF) and its receptors play important roles in the regulation of angiogenesis during physiological and pathological processes. It is thought that AML cells have an autocrine VEGF pathway that contributes to the development and progression of AML. In addition, growing evidence has suggested that numerous microRNAs are involved in AML. The present study aimed to investigate the relationship between VEGF dysregulation and microRNA profiles in AML cells and patients. VEGF-overexpressing and VEGF-knockdown leukemia cells were constructed and changes in the patterns of microRNA expression were analyzed using a microRNA array. Subsequently, mononuclear cells from the blood of patients with AML showing high or low expression levels of VEGF were obtained and were used to assess the patterns of microRNA expression by reverse transcription-quantitative polymerase chain reaction. The results of the present study suggested that downregulation of VEGF markedly altered the profile of microRNAs in AML cells, while upregulation of VEGF did not. Examination of clinical samples from patients with AML showed that several microRNAs were closely associated with the expression level of VEGF, including miR-20a, miR-93, miR-16-5p, miR-17-5p, miR-124-5p and miR-17-3p. These results suggested that VEGF may be a pivotal protein that can both receive and initiate signals in leukemia cells.

Sevoflurane inhibits the migration and invasion of glioma cells by upregulating microRNA-637

Cancer cell migration and invasion are essential features of the metastatic process. Volatile anesthetic sevoflurane inhibits the migration and invasion of multiple cancer cell lines; however, its effects on glioma cells are unclear. Emerging evidence suggests that microRNA (miRNA)-637 regulates glioma cell migration and invasion through the Akt1 pathway. Sevoflurane has been shown to modulate a number of miRNAs. In the present study, we examined whether sevoflurane inhibits glioma cell migration and invasion and, if so, whether these beneficial effects are mediated by miRNA-637. U251 glioma cells were treated without (control) or with sevoflurane at low, moderate or high concentrations for 6 h. To explore the molecular mechanisms, an additional group of U251 cells was treated with a miRNA‑637 inhibitor prior to treatment with a high concentration of sevoflurane. Compared with the control group, sevoflurane inhibited the migration and invasion of U251 cells in a dose-dependent manner. Molecular analyses revealed that sevoflurane increased the expression of miRNA‑637 and decreased the expression of Akt1 and phosphorylated Akt1 in a dose-dependent manner. Moreover, the inhibitory effects of sevoflurane on U251 cell migration and invasion were completely abolished by pre-treatment with miRNA‑637 inhibitor, which reversed the sevoflurane-induced reduction in the expression of Akt1 and phosphorylated Akt1 in the U251 cells. These results demonstrate that sevoflurane inhibits glioma cell migration and invasion and that these beneficial effects are mediated by the upregulation of miRNA‑637, which suppresses Akt1 expression and activity. These findings may have significant clinical implications for anesthesiologists regarding the choice of volatile anesthetic agents for the surgical resection of gliomas to prevent metastases and improve patient outcomes.

miR-520e regulates cell proliferation, apoptosis and migration in breast cancer

Previous studies have indicated that the deregulation of microRNAs contributes to tumorigenesis. Misregulation of microRNA-520e (miR-520e) has been observed in various types of cancer. However, the expression profile and biological function of miR-520e in breast cancer remains largely unknown. The present study demonstrated that miR-520e expression was significantly increased in breast cancer tissues compared with adjacent non-cancerous breast tissues in 21 patients, as revealed by reverse transcription-quantitative polymerase chain reaction. Furthermore, the proliferation capacity of breast cancer cells was markedly enhanced by the introduction of miR-520e in vitro using a cell counting kit-8 assay. The present study also revealed that the overexpression of miR-520e could suppress breast cancer cell apoptosis, revealed using Annexin V/propidium iodide double staining and flow cytometry analysis. In addition, the ectopic expression of miR-520e promoted the migration of breast cancer cells in vitro, as demonstrated by a Transwell assay. Overall, the findings of the present study highlight an important role for miR-520e in breast cancer development and in the molecular etiology of breast cancer, which indicates the potential application of miR-520e in cancer therapy.

Prioritizing cancer-related microRNAs by integrating microRNA and mRNA datasets

MicroRNAs (miRNAs) are small non-coding RNAs regulating the expression of target genes, and they are involved in cancer initiation and progression. Even though many cancer-related miRNAs were identified, their functional impact may vary, depending on their effects on the regulation of other miRNAs and genes. In this study, we propose a novel method for the prioritization of candidate cancer-related miRNAs that may affect the expression of other miRNAs and genes across the entire biological network. For this, we propose three important features: the average expression of a miRNA in multiple cancer samples, the average of the absolute correlation values between the expression of a miRNA and expression of all genes, and the number of predicted miRNA target genes. These three features were integrated using order statistics. By applying the proposed approach to four cancer types, glioblastoma, ovarian cancer, prostate cancer, and breast cancer, we prioritized candidate cancer-related miRNAs and determined their functional roles in cancer-related pathways. The proposed approach can be used to identify miRNAs that play crucial roles in driving cancer development, and the elucidation of novel potential therapeutic targets for cancer treatment.

MicroRNAs in glioblastoma multiforme pathogenesis and therapeutics

Glioblastoma multiforme (GBM) is the most common and lethal cancer of the adult brain, remaining incurable with a median survival time of only 15 months. In an effort to identify new targets for GBM diagnostics and therapeutics, recent studies have focused on molecular phenotyping of GBM subtypes. This has resulted in mounting interest in microRNAs (miRNAs) due to their regulatory capacities in both normal development and in pathological conditions such as cancer. miRNAs have a wide range of targets, allowing them to modulate many pathways critical to cancer progression, including proliferation, cell death, metastasis, angiogenesis, and drug resistance. This review explores our current understanding of miRNAs that are differentially modulated and pathologically involved in GBM as well as the current state of miRNA-based therapeutics. As the role of miRNAs in GBM becomes more well understood and novel delivery methods are developed and optimized, miRNA-based therapies could provide a critical step forward in cancer treatment.

miRNA involvement in angiogenesis in age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly. Late-stage AMD is characterized by choroidal neovascularization (CNV). miR-93 appears to play a role in regulating vascular endothelial growth factor-A (VEGF-A), a known factor involved in neovascularization. Understanding its biological significance might enable development of therapeutic interventions for diseases like AMD. We aimed to determine the role of miR-93 in AMD using a laser-induced CNV mouse model. CNV was induced by laser photocoagulation in C57BL/6 mice. The CNV mice were transfected with scrambled miR or miR-93 mimic. The treatment effect was assessed by fundus photography and fluorescein angiography and confirmed by choroidal flatmount. The expression of miR-93 and VEGF-A in ocular tissues was analysed by quantitative polymerase chain reaction (qPCR) and Western blot. The overexpression effects of miR-93 were also proved on human microvascular endothelial cells (HMECs). Significantly decreased expression of miR-93 was observed by qPCR analysis in CNV mice compared to untreated mice (p < 0.05). VEGF-A messenger RNA (mRNA) and protein expression were upregulated with CNV; these changes were ameliorated by restoration of miR-93 (p < 0.05). CNV was reduced after miR-93 transfection. Transfection of miR-93 reduced the proliferation of HMECs (p < 0.01), but no significant changes were observed in 2D capillary-like tube formation (p > 0.05) and migration (p > 0.05) compared with that in the untreated cells. miR-93 has been shown to be a negative modulator of angiogenesis in the eye. All together, these results highlight the therapeutic potential of miR-93 and suggest that it may contribute as a putative therapeutic target for AMD in humans.

MicroRNA-93 promotes the malignant phenotypes of human glioma cells and induces their chemoresistance to temozolomide

MicroRNAs (miRNAs), a class of small non-coding RNAs, can induce mRNA degradation or repress translation by binding to the 3'-untranslated region (UTR) of its target mRNA. Recently, some specific miRNAs, e.g. miR-93, have been found to be involved in pathological processes by targeting some oncogenes or tumor suppressors in glioma. However, the regulatory mechanism of miR-93 in the biological behaviors and chemoresistance of glioma cells remains unclear. In the present study, in situ hybridization and real-time RT-PCR data indicated that miR-93 was significantly upregulated in glioma patients (n=43) compared with normal brain tissues (n=8). Moreover, the upregulated miR-93 level was significantly associated with the advanced malignancy. We also found that upregulation of miR-93 promoted the proliferation, migration and invasion of glioma cells, and that miR-93 was involved in the regulation of cell cycle progression by mediating the protein levels of P21, P27, P53 and Cyclin D1. P21 was further identified as a direct target of miR-93. Knockdown of P21 attenuated the suppressive effects of miR-93 inhibition on cell cycle progression and colony formation. In addition, inhibition of miR-93 enhanced the chemosensitization of glioma cells to temozolomide (TMZ). Based on these above data, our study demonstrates that miR-93, upregulated in glioma, promotes the proliferation, cell cycle progression, migration and invasion of human glioma cells and suppresses their chemosensitivity to TMZ. Therefore, miR-93 may become a promising diagnostic marker and therapeutic target for glioma.

Micro ribonucleic acid-93 promotes oncogenesis of cervical cancer by targeting RAB11 family interacting protein 1

AIM

Micro ribonucleic acid (RNA)-93 (miR-93) is a novel oncogenic miRNA dysregulated in many types of tumors. We aimed to further study the expression pattern and clinical significance of miR-93 and its target, the RAB11 family interacting protein 1 (RAB11FIP1) gene, in cervical cancer.

METHODS

Mir-93 and RAB11FIP1 expression in cervical cancer (n = 168), cervical intraepithelial neoplasia (CIN) 2 or 3 (n = 60) and normal cervical tissues (n = 48) was examined by real-time reverse transcription polymerase chain reaction and immunohistochemical staining. Methyl thiazolyl tetrazolium assay, flow cytometry, and Transwell chamber invasion assay were performed to investigate the function of miR-93 in the proliferation, apoptosis and invasion of cervical cancer cell lines SiHa and CaSki. Luciferase activity assay was conducted to identify the target gene of miR-93.

RESULTS

Mir-93 expression levels in cervical cancer and CIN tissues were significantly increased (P = 0.032), but the RAB11FIP1 protein was significantly decreased (P = 0.006) compared with normal tissues. Neither was associated with clinicopathological variables. Enforced miR-93 knockdown or RAB11FIP1 overexpression suppressed proliferation and promoted apoptosis, but did not influence invasion in cervical cancer cells. Luciferase activity indicated that RAB11FIP1 was a direct target for miR-93.

CONCLUSIONS

Our findings suggest that overexpression of miR-93 via targeting RAB11FIP1 as an early event plays an important role in oncogenesis of cervical cancer. MiR-93 and its target protein RAB11FIP1 may be potential therapeutic targets for cervical cancer and its precursors.

Essential role of miRNAs in orchestrating the biology of the tumor microenvironment

MicroRNAs (miRNAs) are emerging as central players in shaping the biology of the Tumor Microenvironment (TME). They do so both by modulating their expression levels within the different cells of the TME and by being shuttled among different cell populations within exosomes and other extracellular vesicles. This review focuses on the state-of-the-art knowledge of the role of miRNAs in the complexity of the TME and highlights limitations and challenges in the field. A better understanding of the mechanisms of action of these fascinating micro molecules will lead to the development of new therapeutic weapons and most importantly, to an improvement in the clinical outcome of cancer patients.

Targeting oncomiRNAs and mimicking tumor suppressor miRNAs: Νew trends in the development of miRNA therapeutic strategies in oncology (Review)

MicroRNA (miRNA or miR) therapeutics in cancer are based on targeting or mimicking miRNAs involved in cancer onset, progression, angiogenesis, epithelial-mesenchymal transition and metastasis. Several studies conclusively have demonstrated that miRNAs are deeply involved in tumor onset and progression, either behaving as tumor-promoting miRNAs (oncomiRNAs and metastamiRNAs) or as tumor suppressor miRNAs. This review focuses on the most promising examples potentially leading to the development of anticancer, miRNA-based therapeutic protocols. The inhibition of miRNA activity can be readily achieved by the use of miRNA inhibitors and oligomers, including RNA, DNA and DNA analogues (miRNA antisense therapy), small molecule inhibitors, miRNA sponges or through miRNA masking. On the contrary, the enhancement of miRNA function (miRNA replacement therapy) can be achieved by the use of modified miRNA mimetics, such as plasmid or lentiviral vectors carrying miRNA sequences. Combination strategies have been recently developed based on the observation that i) the combined administration of different antagomiR molecules induces greater antitumor effects and ii) some anti-miR molecules can sensitize drug-resistant tumor cell lines to therapeutic drugs. In this review, we discuss two additional issues: i) the combination of miRNA replacement therapy with drug administration and ii) the combination of antagomiR and miRNA replacement therapy. One of the solid results emerging from different independent studies is that miRNA replacement therapy can enhance the antitumor effects of the antitumor drugs. The second important conclusion of the reviewed studies is that the combination of anti-miRNA and miRNA replacement strategies may lead to excellent results, in terms of antitumor effects.

How Does Transcranial Magnetic Stimulation Influence Glial Cells in the Central Nervous System?

Transcranial magnetic stimulation (TMS) is widely used in the clinic, and while it has a direct effect on neuronal excitability, the beneficial effects experienced by patients are likely to include the indirect activation of other cell types. Research conducted over the past two decades has made it increasingly clear that a population of non-neuronal cells, collectively known as glia, respond to and facilitate neuronal signaling. Each glial cell type has the ability to respond to electrical activity directly or indirectly, making them likely cellular effectors of TMS. TMS has been shown to enhance adult neural stem and progenitor cell (NSPC) proliferation, but the effect on cell survival and differentiation is less certain. Furthermore there is limited information regarding the response of astrocytes and microglia to TMS, and a complete paucity of data relating to the response of oligodendrocyte-lineage cells to this treatment. However, due to the critical and yet multifaceted role of glial cells in the central nervous system (CNS), the influence that TMS has on glial cells is certainly an area that warrants careful examination.

miR-93 functions as an oncomiR for the downregulation of PDCD4 in gastric carcinoma

Programmed cell death 4 (PDCD4), as a tumor suppressor gene, is frequently reduced in a variety of tumors, including gastric cancer. Previous findings have indicated that PDCD4 participates in tumorigenesis through the regulation of apoptosis, but the molecular basis of this process has not been fully elucidated, and no studies have shown the upstream regulation of this gene in gastric cancer. In this study, we used bioinformatics analysis to search for miRNAs that could potentially target PDCD4 and identified miR-93 as a candidate. Moreover, we observed the inverse correlation between miR-93 and PDCD4 protein levels, but not mRNA levels, in human gastric cancer tissues. We further experimentally validated PDCD4 as the direct target of miR-93 by evaluating PDCD4 expression in gastric cancer cells after the overexpression or knockdown of miR-93. Additionally, the biological consequences of targeting PDCD4 through miR-93 were examined using cell apoptosis assays in vitro. We demonstrated that the repression of PDCD4 through miR-93 suppressed the apoptosis of gastric cancer cells. Finally, we revealed that miR-93 promoted the development of gastric tumor growth in xenograft mice by negatively regulating PDCD4. Taken together, the findings of the present study indicated the oncogenic role of miR-93 in gastric cancer tumorigenesis through targeting PDCD4, particularly in apoptosis.

MicroRNA miR-93-5p regulates expression of IL-8 and VEGF in neuroblastoma SK-N-AS cells

The role of the microRNA miR-93-5p on the secretome profile and the expression levels of vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) was investigated in the neuroblastoma SK-N-AS cell line by Bio-Plex analysis and RT-qPCR. The results indicate that VEGF and IL-8 are the major miR-93-5p molecular targets. This conclusion was based on in vitro transfection with pre-miR-93-5p and anti-miR-93-5p; these treatments inversely modulated both VEGF and IL-8 gene expression and protein release in the neuroblastoma SK-N-AS cell line. Computational analysis showed the presence of miR-93-5p consensus sequences in the 3'UTR region of both VEGF and IL-8 mRNAs, predicting possible interaction with miR-93-5p and confirming a potential regulatory role of this microRNA.

MicroRNA and extracellular vesicles in glioblastoma: small but powerful

To promote the tumor growth, angiogenesis, metabolism, and invasion, glioblastoma (GBM) cells subvert the surrounding microenvironment by influencing the endogenous activity of other brain cells including endothelial cells, macrophages, astrocytes, and microglia. Large number of studies indicates that the intra-cellular communication between the different cell types of the GBM microenvironment occurs through the functional transfer of oncogenic components such as proteins, non-coding RNAs, DNA and lipids via the release and uptake of extracellular vesicles (EVs). Unlike the communication through the secretion of chemokines and cytokines, the transfer and gene silencing activity of microRNAs through EVs is more complex as the biogenesis and proper packaging of microRNAs is crucial for their uptake by recipient cells. Although the specific mechanism of EV-derived microRNA uptake and processing in recipient cells is largely unknown, the screening, identifying and finally targeting of the EV-associated pro-tumorigenic microRNAs are emerging as new therapeutic strategy to combat the GBM.

Identification of Dormancy-Associated MicroRNAs for the Design of Osteosarcoma-Targeted Dendritic Polyglycerol Nanopolyplexes

The presence of dormant, microscopic cancerous lesions poses a major obstacle for the treatment of metastatic and recurrent cancers. While it is well-established that microRNAs play a major role in tumorigenesis, their involvement in tumor dormancy has yet to be fully elucidated. We established and comprehensively characterized pairs of dormant and fast-growing human osteosarcoma models. Using these pairs of mouse tumor models, we identified three novel regulators of osteosarcoma dormancy: miR-34a, miR-93, and miR-200c. This report shows that loss of these microRNAs occurs during the switch from dormant avascular into fast-growing angiogenic phenotype. We validated their downregulation in patients' tumor samples compared to normal bone, making them attractive candidates for osteosarcoma therapy. Successful delivery of miRNAs is a challenge; hence, we synthesized an aminated polyglycerol dendritic nanocarrier, dPG-NH2, and designed dPG-NH2-microRNA polyplexes to target cancer. Reconstitution of these microRNAs using dPG-NH2 polyplexes into Saos-2 and MG-63 cells, which generate fast-growing osteosarcomas, reduced the levels of their target genes, MET proto-oncogene, hypoxia-inducible factor 1α, and moesin, critical to cancer angiogenesis and cancer cells' migration. We further demonstrate that these microRNAs attenuate the angiogenic capabilities of fast-growing osteosarcomas in vitro and in vivo. Treatment with each of these microRNAs using dPG-NH2 significantly prolonged the dormancy period of fast-growing osteosarcomas in vivo. Taken together, these findings suggest that nanocarrier-mediated delivery of microRNAs involved in osteosarcoma tumor-host interactions can induce a dormant-like state.

Elevated serum miR-93, miR-191, and miR-499 are noninvasive biomarkers for the presence and progression of traumatic brain injury

The levels of miR-93, miR-191, and miR-499 have been reported to be up-regulated in the tissues of experimental traumatic brain injury (TBI) rat models. However, the clinical diagnostic and prognostic values of the serum signatures of these 3 miRNAs in TBI remain unclear. The purpose of this study was to determine the expression levels of these 3 microRNAs (miRNAs) in the sera of TBI patients and to evaluate their relationships with the severity and clinical outcome of TBI. The serum levels of these miRNAs were assessed in TBI patients (n = 76) and healthy controls (n = 38) by quantitative reverse-transcription PCR. The severities and clinical outcomes of the TBI patients were evaluated with the Glasgow coma scale and the Glasgow outcome scale. The serum miR-93, miR-191, and miR-499 levels were significantly increased in the TBI patients compared with the controls at all examined time points, and these levels were significantly higher in the patients with severe TBI than in those with moderate or mild TBI (p < 0.05). The serum miR-93, miR-191, and miR-499 levels were significantly higher in the patients with a poor outcome than in those with a good outcome (p < 0.05). The AUCs of miR-93, miR-191, and miR-499 for distinguishing the TBI patients from the healthy controls were 1.000 (p < 0.001), 0.727 (p < 0.001) and 0.801 (p < 0.001), respectively. Interestingly, the AUCs of miR-93, miR-191, and miR-499 for distinguishing the mild TBI patients from the healthy controls were 1.000 (p < 0.001), 0.742 (p < 0.001) and 0.819 (p < 0.001), respectively. Taken together, these results indicate that miR-93, miR-191, and miR-499 are potentially valuable indicators of the diagnosis, severity, and prognosis of TBI. Our study showed that the serum levels of miR-93, miR-191, and miR-499 are all increased in traumatic brain injury (TBI) patients. Their serum levels are associated with TBI severity and outcome, which suggest that these miRNAs play important roles in the pathogenesis and progression of TBI. We think these findings should provide a new strategy for the diagnostic, prognostic, and treatment of TBI.

The effect of antisense inhibitor of miRNA 106b∼25 on the proliferation, invasion, migration, and apoptosis of gastric cancer cell

Accumulating data has demonstrated that miRNA 106b∼25, which are composed of the highly conserved miRNA 106b, miRNA 93, and miRNA 25, play carcinogenic roles in cancers. We investigated the expression of miRNA 106b∼25 in gastric cancer cells (SGC 7901, MGC 803, BGC 823) and normal gastric epithelial cell then inhibited miRNA 106b∼25 expression via transiently transfecting their antisense inhibitor. After miRNA 106b∼25 cluster was inhibited, MTT, Scratch test, Transwell invasion test, and flow cytometry were applied to investigate the proliferation, invasion, migration, cell cycle, and apoptosis of gastric cancer cell. The expression of miRNA 106b, miRNA 93, and miRNA 25 in gastric cancer cells SGC 7901, MGC 803, and BGC 823 was significantly higher than in gastric epithelial cell GES-1. The most significant suppression of miRNA 106b∼25 expressions can be detected in MGC 803 cell after transiently transfecting their antisense inhibitors. So, MGC 803 cell was selected as our research object. After inhibiting miRNA 106b and miRNA 93 respectively and combined, the proliferation, migration, and invasion of gastric cancer cell MGC 803 were significantly suppressed. The most significant suppression was observed in combined inhibiting group. After miRNA 106b∼25 cluster was inhibited respectively or combined, more gastric cancer cells were arrested in the G0G1 phase. However, there was no statistical difference in comparing with control groups. While the percentages of apoptotic cells increased after miRNA 106b∼25 cluster was inhibited, the statistical difference was detected only in combined inhibiting group. Inhibiting miRNA 106b∼25 cluster via transfecting antisense inhibitor can influence biological behavior of gastric cancer cell.

Stromal Expression of miR-143/145 Promotes Neoangiogenesis in Lung Cancer Development

The two unrelated miRNAs miR-143 and miR-145, coexpressed from the miR-143/145 cluster, have been proposed to act as tumor suppressors in human cancer, and therapeutic benefits of delivering miR-143 and miR-145 to tumors have been reported. In contrast, we found that tumor-specific deletion of miR-143/145 in an autochthonous mouse model of lung adenocarcinoma did not affect tumor development. This was consistent with the lack of endogenous miR-143/145 expression in normal and transformed lung epithelium. Surprisingly, miR-143/145 in the tumor microenvironment dramatically promoted tumor growth by stimulating the proliferation of endothelial cells. Loss of miR-143/145 in vivo led to derepression of the miR-145 target CAMK1D, an inhibitory kinase, which when overexpressed prevents mitotic entry of endothelial cells. As a consequence, tumors in miR-143/145-deficient animals exhibited diminished neoangiogenesis, increased apoptosis, and their expansion was limited by the tumor's ability to co-opt the alveolar vasculature. These findings demonstrate that stromal miR-143/145 promotes tumorigenesis and caution against the use of these miRNAs as agents in cancer therapeutics.

SIGNIFICANCE

This study shows that miR-143/145 expressed from the tumor microenvironment stimulates neoangiogenesis and supports tumor expansion in the lung, demonstrating a surprising role for the putative tumor suppressor miRNA cluster in promoting tumorigenesis. We propose inhibition of miR-143/145 as a therapeutic avenue to modulate tumor neoangiogenesis.

MicroRNA: a new and promising potential biomarker for diagnosis and prognosis of ovarian cancer

Epithelial ovarian cancer (EOC) is the leading cause of death among all gynecological malignancies. Despite the technological and medical advances over the past four decades, such as the development of several biological markers (mRNA and proteins biomarkers), the mortality rate of ovarian cancer remains a challenge because of its late diagnosis, which is specifically attributed to low specificities and sensitivities. Under this compulsive scenario, recent advances in expression biology have shifted in identifying and developing specific and sensitive biomarkers, such as microRNAs (miRNAs) for cancer diagnosis and prognosis. MiRNAs are a novel class of small non-coding RNAs that deregulate gene expression at the posttranscriptional level, either by translational repression or by mRNA degradation. These mechanisms may be involved in a complex cascade of cellular events associated with the pathophysiology of many types of cancer. MiRNAs are easily detectable in tissue and blood samples of cancer patients. Therefore, miRNAs hold good promise as potential biomarkers in ovarian cancer. In this review, we attempted to provide a comprehensive profile of key miRNAs involved in ovarian carcinoma to establish miRNAs as more reliable non-invasive clinical biomarkers for early detection of ovarian cancer compared with protein and DNA biomarkers.

Signaling and molecular basis of bone marrow niche angiogenesis in leukemia

Angiogenesis, the process of blood vessel formation, is necessary for tissue survival in normal and pathologic conditions. Increased angiogenesis in BM niche is correlated with leukemia progression and resistance to treatment. Angiogenesis can interfere with disease progression and several angiogenic (such as vascular growth factors) as well as anti-angiogenic factors (i.e. angiostatin) can affect angiogenesis. Furthermore, miRs can affect the angiogenic process by inhibiting angiogenesis or increasing the expression of growth factors. Given the importance of angiogenesis in BM for maintenance of leukemic clones, recognition of angiogenic and anti-angiogenic factors and miRs as well as drug resistance mechanisms of leukemic blasts can improve the therapeutic strategies. We highlight the changes in angiogenic balance within the BM niche in different leukemia types. Moreover, we explored the pathways leading to drug resistance in relation to angiogenesis and attempted to assign interesting candidates for future research.

Noncoding RNAs in Tumor Angiogenesis

Solid tumors require angiogenesis to grow beyond 2 mm in size. In most cases, tumor cells undergo angiogenic switch and secrete substances that are required for generation of new capillary sprouting from existing blood vessels. Tumor angiogenesis is driven by a complex interplay between pro-angiogenic (VEGF/VEGFR, PDGF/PDGFR) and anti-angiogenic factors (TSP-1/TSP-2) within the tumor microenvironment. In addition, control of tissue remodeling and degradation by matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) contribute to tumor angiogenesis. Furthermore, tumor suppressors or oncogenes that control cellular motility and maintain or promote hypoxia (HIFs and MYC) are also actively playing roles in tumor angiogenesis. Noncoding RNAs (ncRNAs), including microRNAs, are a novel class of regulatory molecules that control the gene expression in a posttranscriptional manner. MicroRNAs regulate important physiological processes, such as proliferation, apoptosis, and differentiation, as well as pathological conditions including oncogenesis. Accumulating evidence suggests that microRNAs directly modulate the process of angiogenesis by targeting important angiogenic factors and signaling molecules. Understanding the molecular mechanism behind the regulation of angiogenesis by microRNAs is important due to their therapeutic potential which may lead to improving outcome for cancer patients. Besides, ncRNAs with a regulatory role in angiogenesis, such as long noncoding RNAs (lncRNAs), have been identified in the genome. However, the mechanisms of the vast majority of lncRNAs are currently unknown. For the few lncRNAs characterized at the functional level, accumulating evidence shows that they play important roles in malignant diseases. The function and mechanism in angiogenesis will be described in this chapter.

MicroRNA-148b targets Rho-associated protein kinase 1 to inhibit cell proliferation, migration and invasion in hepatocellular carcinoma

microRNA(miR)-148b has been found to be downregulated in various human malignancies, including hepatocellular carcinoma (HCC) as well as gastric, pancreatic, colon and oral cancer. However, the function of miR‑148b in HCC has remained elusive. The present study examined the effects of miR‑148b on the proliferation, migration and invasion of HCC cells in vitro. After transfection of the HepG2 and SMMC‑7721 HCC cell lines with miR‑148b, an MTT assay, a Transwell migration and invasion assay as well as western blot analysis were performed. miR-148b was shown to inhibit cell proliferation, migration and invasion in the two cell lines. Using a luciferase reporter assay, the present study also provided the first evidence that miR‑148b directly targets Rho‑associated protein kinase 1 in HCC. These results suggested that miR-148 may represent a novel molecular marker and a potential molecular therapeutic for inhibiting metastasis of HCC.

The pseudogene TUSC2P promotes TUSC2 function by binding multiple microRNAs

Various non-coding regions of the genome, once presumed to be ‘junk’ DNA, have recently been found to be transcriptionally active. In particular, pseudogenes are now known to have important biological roles. Here we report that transcripts of the two tumour suppressor candidate-2 pseudogenes (TUSC2P), found on chromosomes X and Y, are homologous to the 3′-UTR of their corresponding protein coding transcript, TUSC2. TUSC2P and the TUSC2 3′-UTR share many common miRNA-binding sites, including miR-17, miR-93, miR-299-3p, miR-520a, miR-608 and miR-661. We find that ectopic expression of TUSC2P and the TUSC2 3′-UTR inhibits cell proliferation, survival, migration, invasion and colony formation, and increases tumour cell death. By interacting with endogenous miRNAs, TUSC2P and TUSC2 3′-UTR arrest the functions of these miRNAs, resulting in increased translation of TUSC2. The TUSC2P and TUSC2 3′-UTR could thus be used as combinatorial miRNA inhibitors and might have clinical applications.

Non-coding RNAs have recently emerged as crucial regulators of gene expression. Here Rutnam et al. identify a pseudogene complementary to the 3′-UTR of the TUSC2 tumour suppressor that regulates TUSC2 levels by acting as a decoy for endogenous microRNAs and thereby inhibits tumorigenesis.

Regulation of IL-8 gene expression in gliomas by microRNA miR-93

Background

Different strategies have been proposed to target neoangiogenesis in gliomas, besides those targeting Vascular Endothelial Growth Factor (VEGF). The chemokine Interleukin-8 (IL-8) has been shown to possess both tumorigenic and proangiogenic properties. Although different pathways of induction of IL-8 gene expression have been already elucidated, few data are available on its post-transcriptional regulation in gliomas.

Methods

Here we investigated the role of the microRNA miR-93 on the expression levels of IL-8 and other pro-inflammatory genes by RT-qPCR and Bio-Plex analysis. We used different disease model systems, including clinical samples from glioma patients and two glioma cell lines, U251 and T98G.

Results

IL-8 and VEGF transcripts are highly expressed in low and high grade gliomas in respect to reference healthy brain; miR-93 expression is also increased and inversely correlated with transcription of IL-8 and VEGF genes. Computational analysis showed the presence of miR-93 consensus sequences in the 3′UTR region of both VEGF and IL-8 mRNAs, predicting possible interaction with miR-93 and suggesting a potential regulatory role of this microRNA. In vitro transfection with pre-miR-93 and antagomiR-93 inversely modulated VEGF and IL-8 gene expression and protein release when the glioma cell line U251 was considered. Similar data were obtained on IL-8 gene regulation in the other glioma cell line analyzed, T98G. The effect of pre-miR-93 and antagomiR-93 in U251 cells has been extended to the secretion of a panel of cytokines, chemokines and growth factors, which consolidated the concept of a role of miR-93 in IL-8 and VEGF gene expression and evidenced a potential regulatory role also for MCP-1 and PDGF (also involved in angiogenesis).

Conclusion

In conclusion, our results suggest an increasing role of miR-93 in regulating the level of expression of several genes involved in the angiogenesis of gliomas.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1659-1) contains supplementary material, which is available to authorized users.

Convection-enhanced delivery of an anti-miR is well-tolerated, preserves anti-miR stability and causes efficient target de-repression: a proof of concept

Over-expressed microRNAs (miRs) are promising new targets in glioblastoma (GBM) therapy. Inhibition of over-expressed miRs has been shown to diminish GBM proliferation, invasion and angiogenesis, indicating a significant therapeutic potential. However, the methods utilized for miR inhibition have had low translational potential. In clinical trials convection-enhanced delivery (CED) has been applied for local delivery of compounds in the brain. The aim of this study was to determine if safe and efficient miR inhibition was possible by CED of an anti-miR. We used a highly invasive GBM orthotopic xenograft model and targeted a well-validated miR, let-7a, with a 2'-O-methoxyethyl anti-miR with a combined phosphodiester/phosphorothioate backbone to establish an initial proof of concept. In vitro, anti-let-7a was delivered unassisted to the patient-derived T87 glioblastoma spheroid culture. In vivo, anti-let-7a or saline were administered by CED into orthotopic T87-derived tumors. After 1 month of infusion, tumors were removed and tumor mRNA levels of the target-gene High-mobility group AT-hook 2 (HMGA2) were determined. In vitro, 5 days inhibition was superior to 1 day at de-repressing the let-7a target HMGA2 and the inhibition was stable for 24 h. In vivo, anti-miR integrity was preserved in the pumps and no animals showed signs of severe adverse effects attributable to the anti-miR treatment. HMGA2 tumor level was significantly de-repressed in the anti-miR treated animals. The results showed-as an initial proof of concept-that miRs can be efficiently inhibited using CED delivery of anti-miR. The next step is to apply CED for anti-miR delivery focusing on key oncogenic miRs.

Small indels induced by CRISPR/Cas9 in the 5' region of microRNA lead to its depletion and Drosha processing retardance

MicroRNA knockout by genome editing technologies is promising. In order to extend the application of the technology and to investigate the function of a specific miRNA, we used CRISPR/Cas9 to deplete human miR-93 from a cluster by targeting its 5’ region in HeLa cells. Various small indels were induced in the targeted region containing the Drosha processing site and seed sequences. Interestingly, we found that even a single nucleotide deletion led to complete knockout of the target miRNA with high specificity. Functional knockout was confirmed by phenotype analysis. Furthermore, de novo microRNAs were not found by RNA-seq. Nevertheless, expression of the pri-microRNAs was increased. When combined with structural analysis, the data indicated that biogenesis was impaired. Altogether, we showed that small indels in the 5’ region of a microRNA result in sequence depletion as well as Drosha processing retard.

Overexpression of miRNA-497 inhibits tumor angiogenesis by targeting VEGFR2

Recent studies reported miR-497 exhibited inhibitory effects in various cancers. However, whether miR-497 is involved in inhibiting angiogenesis, which is critical for tumor growth and metastasis, is still unknown. The purpose of this study was to investigate the potential role of miR-497 in tumor angiogenesis. In this work, cell proliferation and apoptosis analyses were conducted to explore the potential function of miR-497 in HUVECs by using MTT and TUNEL assays. Western blotting (WB) was employed to validate the downstream targets of miR-497. Furthermore, in order to disclose the role of miR-497 on angiogenesis, VEGFR2-luc transgenic mice were treated with miR-497 mimic and applied to monitor tumor angiogenesis and growth by in vivo bioluminescent imaging (BLI). The results demonstrated that overexpression of miR-497 showed inhibitory effects on VEGFR2 activation and downstream Raf/MEK/ERK signal pathways in vitro and in vivo. Moreover, overexpression of miR-497 effectively induced HUVECs apoptosis by targeting VEGFR2 and downstream PI3K/AKT signaling pathway. Furthermore, miR-497 exhibited anti-angiogenesis and anti-tumor effects in the VEGFR2-luc breast tumor model proven by BLI, WB and immunohistochemistry analysis. In summary, miR-497 inhibits tumor angiogenesis and growth via targeting VEGFR2, indicating miR-497 can be explored as a potential drug candidate for cancer therapy.

Acute hypoxia induces upregulation of microRNA-210 expression in glioblastoma spheroids

AIM

Tumor hypoxia and presence of tumor stem cells are related to therapeutic resistance and tumorigenicity in glioblastomas. The aim of the present study was therefore to identify microRNAs deregulated in acute hypoxia and to identify possible associated changes in stem cell markers.

MATERIALS & METHODS

Glioblastoma spheroid cultures were grown in either 2 or 21% oxygen. Subsequently, miRNA profiling was performed and expression of ten stem cell markers was examined.

RESULTS

MiRNA-210 was significantly upregulated in hypoxia in patient-derived spheroids. The stem cell markers displayed a complex regulatory pattern.

CONCLUSION

MiRNA-210 appears to be upregulated in hypoxia in immature glioblastoma cells. This miRNA may represent a therapeutic target although it is not clear from the results whether this miRNA may be related to specific cancer stem cell functions.

MiR-93 Controls Adiposity via Inhibition of Sirt7 and Tbx3

Conquering obesity has become a major socioeconomic challenge. Here, we show that reduced expression of the miR-25-93-106b cluster, or miR-93 alone, increases fat mass and, subsequently, insulin resistance. Mechanistically, we discovered an intricate interplay between enhanced adipocyte precursor turnover and increased adipogenesis. First, miR-93 controls Tbx3, thereby limiting self-renewal in early adipocyte precursors. Second, miR-93 inhibits the metabolic target Sirt7, which we identified as a major driver of in vivo adipogenesis via induction of differentiation and maturation of early adipocyte precursors. Using mouse parabiosis, obesity in mir-25-93-106b(-/-) mice could be rescued by restoring levels of circulating miRNA and subsequent inhibition of Tbx3 and Sirt7. Downregulation of miR-93 also occurred in obese ob/ob mice, and this phenocopy of mir-25-93-106b(-/-) was partially reversible with injection of miR-93 mimics. Our data establish miR-93 as a negative regulator of adipogenesis and a potential therapeutic option for obesity and the metabolic syndrome.

The Emerging Role of miRNAs in HTLV-1 Infection and ATLL Pathogenesis

Human T-cell leukemia virus (HTLV)-1 is a human retrovirus and the etiological agent of adult T-cell leukemia/lymphoma (ATLL), a fatal malignancy of CD4/CD25+ T lymphocytes. In recent years, cellular as well as virus-encoded microRNA (miRNA) have been shown to deregulate signaling pathways to favor virus life cycle. HTLV-1 does not encode miRNA, but several studies have demonstrated that cellular miRNA expression is affected in infected cells. Distinct mechanisms such as transcriptional, epigenetic or interference with miRNA processing machinery have been involved. This article reviews the current knowledge of the role of cellular microRNAs in virus infection, replication, immune escape and pathogenesis of HTLV-1.

Decreased Expression of MiRNA-204-5p Contributes to Glioma Progression and Promotes Glioma Cell Growth, Migration and Invasion

Gliomas are the most common malignant primary brain tumors in adults and exhibit a spectrum of aberrantly aggressive phenotype. Although increasing evidence indicated that the deregulation of microRNAs (miRNAs) contributes to tumorigenesis and invasion, little is known about the roles of miR-204-5p in human gliomas. In the present study, the expression of miR-204-5p in clinical glioma tissues was measured by qRT-PCR. The effects of miR-204-5p on glioma cell growth and metastasis were examined by overexpressing or inhibiting miR-204-5p. We found that the expression level of miR-204-5p was significantly reduced in clinical glioma tissues compared with normal brain tissues. Moreover, we revealed that the introduction of miR-204-5p dramatically suppressed glioma cell growth, migration and invasion. Furthermore, mechanistic investigations revealed that RAB22A, a member of the RAS oncogene family, is a direct functional target of miR-204-5p in gliomas. In vivo, restoring miR-204-5p expression in glioma cells suppressed tumorigenesis and increased overall host survival. Our findings suggest that miR-204-5p is a cancer suppressor miRNA and overexpression of miR-204-5p is a novel glioma treatment strategy.

Experimental procedures to identify and validate specific mRNA targets of miRNAs

Functionally matured microRNAs (miRNAs) are small single-stranded non-coding RNA molecules which are emerging as important post-transcriptional regulators of gene expression and consequently are central players in many physiological and pathological processes. Since the biological roles of individual miRNAs will be dictated by the mRNAs that they regulate, the identification and validation of miRNA/mRNA target interactions is critical for our understanding of the regulatory networks governing biological processes. We promulgate the combined use of prediction algorithms, the examination of curated databases of experimentally supported miRNA/mRNA interactions, manual sequence inspection of cataloged miRNA binding sites in specific target mRNAs, and review of the published literature as a reliable practice for identifying and prioritizing biologically important miRNA/mRNA target pairs. Once a preferred miRNA/mRNA target pair has been selected, we propose that the authenticity of a functional miRNA/mRNA target pair be validated by fulfilling four well-defined experimental criteria. This review summarizes our current knowledge of miRNA biology, miRNA/mRNA target prediction algorithms, validated miRNA/mRNA target data bases, and outlines several experimental methods by which miRNA/mRNA targets can be authenticated. In addition, a case study of human endoglin is presented as an example of the utilization of these methodologies.

Differential expression of microRNAs in periurethral vaginal wall tissues of postmenopausal women with and without stress urinary incontinence

OBJECTIVE

The aims of this study were to investigate microRNA (miRNA) expression profiles in the periurethral vaginal wall tissues of postmenopausal women with and without stress urinary incontinence (SUI) and to explore the putative target genes associated with SUI via miRNA-messenger RNA (mRNA) pair prediction.

METHODS

Periurethral vaginal wall tissues of postmenopausal women with SUI (n = 13) and matched continent postmenopausal women (n = 13) were collected during transvaginal surgical operation. Total RNAs were extracted and miRNAs were profiled by TaqMan Array Human MicroRNA assays in three case-control pairs. TargetScanS, PicTar, and miRanda were used to obtain the putative miRNA-mRNA pairs based on sequence data, and three pairs were predicated. The relative expression levels of miRNAs in predicated miRNA-mRNA pairs were quantified in 10 other case-control pairs by real-time polymerase chain reaction. The expression levels of mRNAs and corresponding proteins were estimated via real-time polymerase chain reaction and Western blot analysis.

RESULTS

Twelve miRNAs were identified to be differentially expressed between two groups: the significantly up-regulated let-7a, miR-101#, miR-125b-2#, miR-190b, and miR-892b, and the down-regulated miR-124, miR-330-3p, miR-485-3p, miR-517b, miR-523, miR-589, and miR-93#. Moreover, three miRNA-mRNA pairs of interest were established via computational algorithms: miR-124 and growth factor receptor-bound protein 2; miR-330-3p and bicaudal D homolog 2; and miR-93# and signal transducer and activator of transcription 3. The expression levels of the three miRNAs were quantified, and a reduction in SUI was revealed. On the other hand, increased expression levels of predicated mRNAs and their protein products were detected.

CONCLUSIONS

This study reports the differential expression of 12 miRNAs in SUI and predicates three miRNA-mRNA pairs. Interestingly, all three predicated target genes are associated with neurodegenerative conditions, indicating the potential significance of neurodegenerative mechanisms in the etiology of SUI.

Microarray analysis of the aberrant microRNA expression pattern in gliomas of different grades

Previous studies have focused on miRNA expression in brain gliomas. However, both the expression pattern of miRNAs in gliomas of different grades and various miRNAs involved in malignant progression of gliomas are poorly understood. In the present study, we used miRNA microarray-based screening to investigate the miRNA expression profile in gliomas, which was further verified by qRT-PCR in selected miRNAs. In total, we found 13 differentially expressed miRNAs between gliomas and their matched surrounding tissues. Among them, 12 miRNAs were upregulated and only one (miR-4489) was downregulated compared with the control. Furthermore, the lower expression level of miR-4489 was confirmed by qRT-PCR in 26 glioma samples. Our microarray result revealed 8, 9 and 15 aberrantly expressed miRNAs in gliomas of World Health Organization (WHO) grade II-IV, respectively. Gene Ontology (GO) and Pathway analysis indicated that target genes of the 13 miRNAs were significantly enriched in central nervous system- and tumor-related biological processes and signaling pathways. The dysregulated miRNAs identified in the present study contribute to the tumorigenesis and malignant progression of gliomas and may serve as useful markers for advanced glioma pathological grading and prognosis.

MicroRNA-93 promotes ovarian granulosa cells proliferation through targeting CDKN1A in polycystic ovarian syndrome

CONTEXT

MicroRNAs (miRNAs) are small, noncoding RNAs that negatively regulate gene expression post-transcriptionally. Whether differently expressed miRNAs contribute to promoting granulosa cell proliferation in polycystic ovarian syndrome disease (PCOS) remains unknown.

OBJECTIVE

We explored whether certain miRNAs are involved in the ovarian dysfunction of PCOS and the mechanism of increased granulosa cells proliferation. Patients and Cells: miRNA expression was analyzed in excised ovarian cortexes from 16 women with PCOS and 8 non-PCOS. An immortalized human granulosa (KGN) cell was used for the mechanism study.

MAIN OUTCOME MEASURES

Expressions of miRNAs in ovarian cortexes were measured using qRT-PCR and KGN granulosa cells were cultured for proliferation assays after overexpression or inhibition of miR-93 or after insulin treatment. Bioinformatics were used to identify the potential miRNA targets. Protein expression analysis, luciferase assays, and rescue assays were used to confirm the substrate of miR-93.

RESULTS

MiR-93 expression was higher in PCOS ovarian cortex and its identified target, CDKN1A, was downregulated. MiR-93 overexpression promoted cell proliferation and G1 to S transition. Knocking down CDKN1A promoted cell growth and cell cycle progression in granulosa cells, and CDKN1A re-introduction reversed the promotional role of miR-93. High concentrations of insulin induced upregulation of miR-93, stimulated KGN cells proliferation and reduced CDKN1A expression.

CONCLUSIONS

miR-93 was increased in PCOS granulosa cells and targeted CDKN1A to promote proliferation and cell cycle progression. Insulin could upregulate the expression of miR-93 and stimulate cell proliferation. This might provide a new insight into the dysfunction of granulosa cells in PCOS.

MicroRNA-93 promotes cell growth and invasion in nasopharyngeal carcinoma by targeting disabled homolog-2

Dysregulation of microRNAs (miRNAs) has been demonstrated to contribute to malignant progression in nasopharyngeal carcinoma (NPC). We previously reported that miR-93 was significantly upregulated in NPC based on a microarray analysis. However, the potential role and mechanism of action of miR-93 in the initiation and progression of NPC remain largely unknown. Quantitative RT-PCR demonstrated that miR-93 was significantly upregulated in NPC cell lines and clinical specimens. The MTT assay, colony formation assay, anchorage-independent growth, and Transwell migration and invasion assays showed that depletion of miR-93 inhibited NPC cell growth, invasion and migration in vitro and suppressed tumor growth in vivo. Disabled homolog-2 (Dab2) was verified as a miR-93 target gene using Luciferase reporter assays, quantitative RT-PCR and Western blotting and was involved in miR-93-regulated NPC cell growth, invasion and migration. These results indicated that miR-93 plays an important role in the initiation and progression of NPC by targeting Dab2 and the miR-93/Dab2 pathway may contribute to the development of novel therapeutic strategies for NPC in the future.

MicroRNAs as mediators and communicators between cancer cells and the tumor microenvironment

Cancer cells grow in an environment comprised of multiple components that support tumor growth and contribute to therapy resistance. Major cell types in the tumor microenvironment are fibroblasts, endothelial cells and infiltrating immune cells all of which communicate with cancer cells. One way that these cell types promote cancer progression is by altering the expression of microRNAs (miRNAs), small noncoding RNAs that negatively regulate protein expression, either in the cancer cells or in the associated normal cells. Changes in miRNA expression can be brought about by direct interaction between the stromal cells and cancer cells, by paracrine factors secreted by any of the cell types or even through direct communication between cells through secreted miRNAs. Understanding the role of miRNAs in the complex interactions between the tumor and cells in its microenvironment is necessary if we are to understand tumor progression and devise new treatments.

MicroRNA-93 regulates collagen loss by targeting MMP3 in human nucleus pulposus cells

OBJECTIVES

Degenerated disc disease is one of the most common medical conditions in patients suffering from low back pain. Recent studies have shown that microRNAs can regulate cell function in many pathological conditions. The aim of this study was to investigate expression and role of miR-93 in disc degeneration.

MATERIALS AND METHODS

Quantitative RT-PCR was employed to investigate level of miR-93 in degenerative nucleus pulposus (NP) tissues. Then, functional analysis of miR-93 in regulating collagen II expression was performed. Subsequently, western blotting and luciferase reporter assay were used to detect the target gene.

RESULTS

We showed that miR-93 was significantly down-regulated in degenerative NP tissues and its levels were associated with grade of disc degeneration. Overexpression of miR-93 stimulated type II collagen expression in NP cells. Moreover, MMP3 was identified as a putative target of miR-93. MiR-93 inhibited MMP3 expression by directly targeting its 3'UTR, and this was abolished by miR-93 binding site mutations. Additionally, restoration of MMP3 in miR-93-overexpressed NP cells reversed effects of type II collagen expression. Expression of MMP3 inversely correlated with miR-93 expression in degenerative NP tissues.

CONCLUSIONS

Taken together, we demonstrated that miR-93 contributed to abnormal NP cell type II collagen expression by targeting MMP3, involved in intervertebral disc degeneration.

Enhanced expression of DNA polymerase eta contributes to cisplatin resistance of ovarian cancer stem cells

Cancer stem cells (CSCs) with enhanced tumorigenicity and chemoresistance are believed to be responsible for treatment failure and tumor relapse in ovarian cancer patients. However, it is still unclear how CSCs survive DNA-damaging agent treatment. Here, we report an elevated expression of DNA polymerase η (Pol η) in ovarian CSCs isolated from both ovarian cancer cell lines and primary tumors, indicating that CSCs may have intrinsically enhanced translesion DNA synthesis (TLS). Down-regulation of Pol η blocked cisplatin-induced CSC enrichment both in vitro and in vivo through the enhancement of cisplatin-induced apoptosis in CSCs, indicating that Pol η-mediated TLS contributes to the survival of CSCs upon cisplatin treatment. Furthermore, our data demonstrated a depletion of miR-93 in ovarian CSCs. Enforced expression of miR-93 in ovarian CSCs reduced Pol η expression and increased their sensitivity to cisplatin. Taken together, our data suggest that ovarian CSCs have intrinsically enhanced Pol η-mediated TLS, allowing CSCs to survive cisplatin treatment, leading to tumor relapse. Targeting Pol η, probably through enhancement of miR-93 expression, might be exploited as a strategy to increase the efficacy of cisplatin treatment.

The tumour-promoting receptor tyrosine kinase, EphB4, regulates expression of integrin-β8 in prostate cancer cells

Background

The EphB4 receptor tyrosine kinase is overexpressed in many cancers including prostate cancer. The molecular mechanisms by which this ephrin receptor influences cancer progression are complex as there are tumor-promoting ligand-independent mechanisms in place as well as ligand-dependent tumor suppressive pathways.

Methods

We employed transient knockdown of EPHB4 in prostate cancer cells, coupled with gene microarray analysis, to identify genes that were regulated by EPHB4 and may represent linked tumor-promoting factors. We validated target genes using qRT-PCR and employed functional assays to determine their role in prostate cancer migration and invasion.

Results

We discovered that over 500 genes were deregulated upon EPHB4 siRNA knockdown, with integrin β8 (ITGB8) being the top hit (29-fold down-regulated compared to negative non-silencing siRNA). Gene ontology analysis found that the process of cell adhesion was highly deregulated and two other integrin genes, ITGA3 and ITGA10, were also differentially expressed. In parallel, we also discovered that over-expression of EPHB4 led to a concomitant increase in ITGB8 expression. In silico analysis of a prostate cancer progression microarray publically available in the Oncomine database showed that both EPHB4 and ITGB8 are highly expressed in prostatic intraepithelial neoplasia, the precursor to prostate cancer. Knockdown of ITGB8 in PC-3 and 22Rv1 prostate cancer cells in vitro resulted in significant reduction of cell migration and invasion.

Conclusions

These results reveal that EphB4 regulates integrin β8 expression and that integrin β8 plays a hitherto unrecognized role in the motility of prostate cancer cells and thus targeting integrin β8 may be a new treatment strategy for prostate cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1164-6) contains supplementary material, which is available to authorized users.

Differential regulation of aggressive features in melanoma cells by members of the miR-17-92 complex

The various roles of microRNAs (miRNAs) in controlling the phenotype of cancer cells are the focus of contemporary research efforts. We have recently shown that miR-17 directly targets the ADAR1 gene and thereby enhances melanoma cell aggressiveness. miR-17 and miR-20a belong to the miR-17/92 complex, and their mature forms are identical except for two non-seed nucleotides. Nevertheless, here we show that these two miRNAs carry markedly different effects on melanoma cells. A strong positive correlation was observed between the expression of miR-17 and miR-20a among various melanoma cultures. Luciferase assays showed that miR-17 but not miR-20a directly targets the 3’ untranslated region of the ADAR1 gene. Ectopic expression of these miRNAs in melanoma cells differentially alters the expression of five exemplar TargetScan-predicted target genes: ADAR1, ITGB8, TGFBR2, MMP2 and VEGF-A. Whole-genome expression microarrays confirm a markedly differential effect on the transcriptome. Functionally, over-expression of miR-20a but not of miR-17 in melanoma cells inhibits net proliferation in vitro. The differential functional effect was observed following ectopic expression of the mature miRNA or of the pre-miRNA sequences. This suggests that the two non-seed nucleotides dictate target sequence recognition and overall functional relevance. These miRNAs are clearly not redundant in melanoma cell biology.

Micro ribonucleic acid-93 promotes proliferation and migration of esophageal squamous cell carcinoma by targeting disabled 2

Background

Accumulated evidence has revealed that the dysregulation of micro ribonucleic acids (miRNAs) may contribute to esophageal squamous cell carcinoma (ESCC). MiR-93, which is a member of the miRNA cluster miR-106b∼25, has been widely studied for its tumor promoting effect on different types of cancers. However, our knowledge of miR-93 function in ESCC remains unclear.

Methods

The expression levels of miR-93 in ESCC and the adjacent non-tumor tissues were measured by real-time polymerase chain reaction. Cell counting kit-8, flow cytometry, and 5-ethynyl-2′-deoxyuridine incorporation and transwell migration assays were employed to explore the effects of miR-93 on proliferation and migration capabilities in EC109 cells. To determine the possible target gene of miR-93, cell transfection, Western blot analysis and luciferase reporter gene assays were performed.

Results

A significant upregulation of miR-93 expression in ESCC tissues was determined, combined with a downregulation of the predicted target gene, disabled 2 (DAB2). The introduction of miR-93 significantly promotes cell proliferation, cell cycle progression, and the metastatic capability of EC109 cells. By cell transfection and luciferase reporter assay, DAB2 was confirmed as a direct target of miR-93. In addition, the knockdown of DAB2 by small interfering RNA displayed a consentaneous phenocopy with miR-93 overexpression in EC109 cells.

Conclusion

Our results indicate that miR-93 acts as a tumor promoter in ESCC, and its promotion effects on ESCC cell proliferation and migration depend largely upon DAB2 suppression.