MicroRNA-18a-5p functions as an oncogene by directly targeting IRF2 in lung cancer

lncRNA PART1, manipulated by transcriptional factor FOXP2, suppresses proliferation and invasion in ESCC by regulating the miR‑18a‑5p/SOX6 signaling axis

An increasing number of studies have demonstrated that long non-coding (lnc)RNAs are associated with tumor invasion, metastasis and the prognosis of patients with a variety of different tumors. However, the roles of lncRNA prostate androgen regulated transcript 1 (PART1) in esophageal squamous cell carcinoma (ESCC) remain unknown. In the present study, reverse transcription-quantitative PCR was performed to investigate the levels of PART1, SRY-box transcription factor 6 (SOX6) and miR-18a-5p in ESCC tissues and cells. The functions of PART1 in ESCC were demonstrated using Cell Counting Kit-8 and Matrigel assays. Promoter activity and dual-luciferase reporter assays, RNA immunoprecipitation and western blot analyses were also used to determine the potential mechanisms of PART1 in ESCC cell lines. It was found that PART1 and SOX6 were both downregulated in ESCC tissues and cells, and their low expression levels were associated with TNM stage, lymph node metastasis and poor prognosis in patients with ESCC. Forkhead box protein P2 (FOXP2) exhibited low expression level in ESCC tissues, and its expression was positively correlated with PART1 expression level in ESCC tissues. FOXP2 was found to bind to the promoter region of PART1 to regulate its expression in ESCC cells. Functionally, PART1 overexpression suppressed cell proliferation and invasion, whereas PART1 downregulation promoted cell proliferation and invasion in the ESCC cell lines. Mechanistically, PART1 functions as a competing endogenous (ce)RNA by sponging miR-18a-5p, resulting in the upregulation of the downstream target gene, SOX6, coupled with the inactivation of the β-catenin/c-myc signaling axis, to suppress ESCC cell proliferation and invasion. In conclusion, data from the present study unveil a potential ceRNA regulatory pathway, in which PART1 affects SOX6 expression level by sponging miR-18a-5p, to ultimately suppress ESCC development and progression.

Identification of novel transcription factor-microRNA-mRNA co-regulatory networks in pulmonary large-cell neuroendocrine carcinoma

Background

Large cell neuroendocrine carcinoma (LCNEC) of the lung is a rare neuroendocrine neoplasm. Previous studies have shown that microRNAs (miRNAs) are widely involved in tumor regulation through targeting critical genes. However, it is unclear which miRNAs play vital roles in the pathogenesis of LCNEC, and how they interact with transcription factors (TFs) to regulate cancer-related genes.

Methods

To determine the novel TF-miRNA-target gene feed-forward loop (FFL) model of LCNEC, we integrated multi-omics data from Gene Expression Omnibus (GEO), Transcriptional Regulatory Relationships Unraveled by Sentence-Based Text Mining (TRRUST), Transcriptional Regulatory Element Database (TRED), and The experimentally validated microRNA-target interactions database (miRTarBase database). First, expression profile datasets for mRNAs (GSE1037) and miRNAs (GSE19945) were downloaded from the GEO database. Overlapping differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) were identified through integrative analysis. The target genes of the FFL were obtained from the miRTarBase database, and the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses were performed on the target genes. Then, we screened for key miRNAs in the FFL and performed gene regulatory network analysis based on key miRNAs. Finally, the TF-miRNA-target gene FFLs were constructed by the hypergeometric test.

Results

A total of 343 DEGs and 60 DEMs were identified in LCNEC tissues compared to normal tissues, including 210 down-regulated and 133 up-regulated genes, and 29 down-regulated and 31 up-regulated miRNAs. Finally, the regulatory network of TF-miRNA-target gene was established. The key regulatory network modules included ETS1-miR195-CD36, TAOK1-miR7-1-3P-GRIA1, E2F3-miR195-CD36, and TEAD1-miR30A-CTHRC1.

Conclusions

We constructed the TF-miRNA-target gene regulatory network, which is helpful for understanding the complex LCNEC regulatory mechanisms.

The Emerging Roles of Autophagy-Related MicroRNAs in Cancer

Autophagy is a conserved catabolic process involving the degradation and recycling of damaged biomacromolecules or organelles through lysosomal-dependent pathways and plays a crucial role in maintaining cell homeostasis. Consequently, abnormal autophagy is associated with multiple diseases, such as infectious diseases, neurodegenerative diseases and cancer. Currently, autophagy is considered to be a dual regulator in cancer, functioning as a suppressor in the early stage while supporting the growth and metastasis of cancer cells in the later stage and may also produce therapeutic resistance. MicroRNAs (miRNAs) are small, non-coding RNA molecules that regulate gene expression at the post-transcriptional level by silencing targeted mRNA. MiRNAs have great regulatory potential for several fundamental biological processes, including autophagy. In recent years, an increasing number of studies have linked miRNA dysfunction to the growth, metabolism, migration, metastasis, and responses of cancer cells to therapy. Therefore, the study of autophagy-related miRNAs in cancer will provide insights into cancer biology and lead to the development of novel anti-cancer strategies. In the present review, we summarise the current knowledge of miRNA dysregulation during autophagy in cancer, focusing on the relationship between autophagy and miRNAs, and discuss their involvement in cancer biology and cancer treatment.

Circular RNA hsa_circ_0000658 inhibits osteosarcoma cell proliferation and migration via the miR-1227/IRF2 axis

Osteosarcoma (OS) is the most frequently occurring bone cancer. Circular RNAs (circRNAs) have been shown to exert pivotal impact in modulation of gene expression, but their roles in OS are still not fully understood. In this study, we analysed the role of circ‐0000658 in OS. Thereafter, molecular techniques such as Western blot, qRT‐PCR, RNA‐binding protein immunoprecipitation and Dual‐Luciferase reporter assays were implemented to investigate the role of circ‐0000658/miR‐1227/interferon regulatory factor‐2 (IRF2) axis in OS. Eventually, the impact of circ‐0000658 on tumour growth and metastasis was observed in a xenograft mouse model. The results of this study revealed that circ‐0000658 exhibits low levels in OS tissues and cell lines. Moreover, circ‐0000658 repression promoted cell cycle, proliferation, invasion and migration but inhibited the apoptosis of OS cells. Researches have previously shown that circ‐0000658 contains a binding site for miR‐1227 and thus can abundantly sponge miR‐1227 to up‐regulate the expression of its target gene IRF2. Moreover, both inhibition of miR‐1227 and overexpression of IRF2 reversed cell proliferation and invasion, which was triggered by circ‐0000658 repression. Conclusively, circ‐0000658 modulates biological function of OS cells through the miR‐1227/IRF2 axis. Therefore, circ‐0000658 might act as a possible novel therapeutic target for the treatment of OS.

The lncRNA SNHG15/miR-18a-5p axis promotes cell proliferation in ovarian cancer through activating Akt/mTOR signaling pathway

Here, we report the expression pattern, function and regulatory mechanism of SNHG15 together with miR-18a-5p micro RNA in ovarian cancer (OC) for the first time. We recruited 20 patients and took normal ovarian tissues and ovarian tumor tissues from them. We used cell culture, transfection, in vivo tumor xenograft assay, and multiple types of detection assays to investigate the expression and regulation of long noncoding RNA (lncRNA) SNHG15/miR-18a-5p in ovarian tissues and cells. Results: We found that the messenger RNA expression level of SNHG15 was significantly higher and miR-18 was decreased in ovarian cancer tissues and in OC cells. Functional experiments showed that SNHG15 overexpression potentiated the migration and invasion of OC cells, while SNHG15 inhibition reduced the tumor proliferation, which was restored via overexpression of miR-18a. SNHG15 was found to directly target and suppress the expression of miR-18a. Our results illustrate the possible molecular mechanism of lncRNA SNHG15/miR-18a-5p functions in cell proliferation in OC. SNHG15/miR-18a promoted the progression of OC cells via the protein kinase B/mammalian target of rapamycin signaling pathway.

miR‑18a‑5p promotes melanoma cell proliferation and inhibits apoptosis and autophagy by targeting EPHA7 signaling

Micro (mi)RNAs serve crucial roles in cancer development although little is known about their cellular mechanisms in the pathogenesis of melanoma. The present study explored the regulatory roles of miR-18a-5p in melanoma cell proliferation, apoptosis and autophagy, in addition to its target gene in melanoma cells. miRNA and ephrin receptor A7 (EPHA7) mRNA were analyzed by reverse transcription-quantitative PCR. Cell Counting Kit-8 and colony formation assays were performed to examine the cell proliferation rate. Hoechst staining and flow cytometry were performed to investigate cell apoptosis. Western blotting was used to estimate the abundance of proteins. Dual-Luciferase reporter assay verified the binding of miRNA with target gene sequences. Melanoma tissues and cell lines exhibited markedly elevated miR-18a-5p expression. miR-18a-5p inhibitor inhibited proliferation rates, and triggered apoptosis and autophagy marker protein expression in WM266-4 and A375 cells. It also negatively regulated EPHA7 expression in WM266-4 and A375 cells by directly binding at the 3′-untranslated region of EPHA7. miR-18a-5p mimics reversed the EPHA7 overexpression-induced suppression of proliferation, and the EPHA7 overexpression-induced promotion of apoptosis and autophagy. miR-18a-5p triggered proliferation of melanoma cells and inhibited apoptosis and autophagy by directly targeting and inhibiting EPHA7 expression. Thus, the present study aided our understanding of miRNA-mediated melanoma pathogenesis.

miR-550a-5p Functions as a Tumor Promoter by Targeting LIMD1 in Lung Adenocarcinoma

Lung adenocarcinoma accounts for half of all lung cancer cases in most countries. Mounting evidence has demonstrated that microRNAs play important roles in cancer progression, and some of them can be identified as potential biomarkers. This study aimed to explore the role of miR-550a-5p, a lung adenocarcinoma-associated mature microRNA screened out from the TCGA database via R-studio and Perl, with abundant expression in samples and with 5-year survival prognosis difference, as well as having not been studied in lung cancer yet. Potential target genes were predicted by the online database. Gene ontology enrichment, pathway enrichment, protein–protein interaction network, and hub genes–microRNA network were constructed by FunRich, STRING database, and Cytoscape. Then, LIMD1, a known tumor suppressor gene reported by multiple articles, was found to have a negative correlation with miR-550a-5p. The expression of miR-550a-5p was up-regulated in tumor samples and tumor-associated cell lines. Its high expression was also correlated with tumor size. Cell line A549 treated with miR-550a-5p overexpression promoted tumor proliferation, while H1299 treated with miR-550a-5p knockdown showed the opposite result. Mechanically, miR-550a-5p negatively regulated LIMD1 by directly binding to its 3′-UTR validated by dual luciferase assay. In summary, a new potential prognostic and therapeutic biomarker, miR-550a-5p, has been identified by bioinformatics analysis and experimental validation in vitro and in vivo, which promotes lung adenocarcinoma by silencing a known suppressor oncogene LIMD1.

Long non-coding RNAs as epigenetic mediator and predictor of glioma progression, invasiveness, and prognosis

Gliomas are aggressive brain tumors with high mortality rate. Over the past several years, non-coding RNAs, specifically the long non-coding RNAs (lncRNAs), have emerged as biomarkers of considerable interest. Emerging data reveals distinct patterns of expressions of several lncRNAs in the glioma tissues, relative to their expression in normal brains. This has led to the speculation for putative exploitation of lncRNAs as diagnostic biomarkers as well as biomarkers for targeted therapy. With a focus on lncRNAs that have shown promise as epigenetic biomarkers in the proliferation, migration, invasion, angiogenesis and metastasis in various glioma models, we discuss several such lncRNAs. The data from cell line / animal model-based studies as well as analysis from human patient samples is presented for the most up-to-date information on the topic. Overall, the information provided herein makes a compelling case for further evaluation of lncRNAs in clinical settings.

Higher expression of miR-150-5p promotes tumorigenesis by suppressing LKB1 in non-small cell lung cancer

Lung cancer is one of the most malignant tumors that can form in the human. MicroRNAs (MiRNAs) play significant role in tumor progression. Human lung cancer tissues and cell lines were used to determine miR-150-5p respectively, and Liver Kinase B1 (LKB1) expression using quantitative real-time PCR (qRT-PCR). The data analysis website Kaplan-Meier Plotter (database obtained from The Cancer Genome Atlas) was used to perform a survival analysis with LKB1 levels. Using the appropriate assays, the function of miR-150-5p was also detected in cellular proliferation, migration and cell apoptosis as well as cell cycle. Results revealed that miR-150-5p was upregulated in non-small cell lung cancer (NSCLC) tissue and cell lines. In NSCLC, miR-150-5p promoted cellular proliferation and migration, but decreased cellular apoptosis. Conversely, miR-150-5p inhibition suppressed cellular growth. These results further revealed a network of cellular signaling for miR-150-5p to target LKB1. Ectopic expression of LKB1 can mitigate the tumor-promoting function of miR-150-5p. Collectively, these results indicated that miR-150-5p may promote lung cancer by inhibiting the suppressor gene LKB1 in NSCLC.

Circulating miRNAs as molecular markers of occupational grain dust exposure

Dust from grain and feed production may cause adverse health effects in exposed workers. In this study we explored circulating miRNAs as potential biomarkers of occupational grain dust exposure. Twenty-two serum miRNAs were analyzed in 44 grain dust exposed workers and 22 controls. Exposed workers had significantly upregulated miR-18a-5p, miR-124-3p and miR-574-3p, and downregulated miR-19b-3p and miR-146a-5p, compared to controls. Putative target genes for the differentially expressed miRNAs were involved in a range of Kyoto Encyclopedia of Genes and Genomes signaling pathways, and ‘Pathways in cancer’ and ‘Wnt signaling pathway’ were common for all the five miRNAs. MiRNA-diseases association analysis showed a link between the five identified miRNAs and several lung diseases terms. A positive correlation between miR-124-3p, miR-18a-5p, and miR-574-3p and IL-6 protein level was shown, while miR-19b-3p was inversely correlated with CC-16 and sCD40L protein levels. Receiver-operating characteristic analysis of the five miRNA showed that three miRNAs (miR-574-3p, miR-124-3p and miR-18a-5p) could distinguish the grain dust exposed group from the control group, with miR-574-3p as the strongest predictor of grain dust exposure. In conclusion, this study identified five signature miRNAs as potential novel biomarkers of grain dust exposure that may have potential as early disease markers.

MiR-18a-5p contributes to enhanced proliferation and migration of PASMCs via targeting Notch2 in pulmonary arterial hypertension

AIM

This study is undertaken to investigate the role and molecular mechanisms of miR-18a-5p in regulating pulmonary arterial hypertension (PAH) pathogenesis.

METHODS

Gene expression and protein levels were determined by qRT-PCR and western blot, respectively; Cell counting kti-8 and Transwell migration assays were used to determine the biological functions of miR-18a-5p in pulmonary arterial smooth muscle cells (PASMCs); bioinformatics analysis, luciferase reporter assays were used to elucidate the mechanisms of miR-18a-5p.

RESULTS

MiR-18a-5p was up-regulated in the clinical samples from PAH patients. PASMCs treated with hypoxia exhibited enhanced proliferative ability and upregulated miR-18a-5p expression. Knockdown of miR-18a-5p attenuated hypoxia-induced hyper-proliferation and enhanced migratory potential of PASMCs; while miR-18a-5p overexpression promoted PASMC proliferation and migration. Further mechanistic studies showed that Notch2 was a direct target of miR-18a-5p and was repressed by miR-18a-5p overexpression. The rescue studies indicated that Notch2 overexpression counteracted the enhanced proliferation and migration induced by miR-18a-5p mimics in PASMCs. Similarly, Notch2 overexpression also block the effects caused by hypoxia in PASMCs. Moreover, Notch2 expression was down-regulated in the PAH patients and was negatively correlated with miR-18a-5p expression. In vivo animal studies further revealed the up-regulation of miR-18a-5p and the down-regulation of Notch2 in the PAH rats.

CONCLUSIONS

Collectively, this study identified the up-regulated miR-18a-5p in the PAH patients; our data suggest that miR-18a-5p contributes to the enhanced proliferation and migration of PASMCs via repressing Notch2 expression.

The MiR-17-92 Gene Cluster is a Blood-Based Marker for Cancer Detection in Non-Small-Cell Lung Cancer

Background

Lung cancer is one of the most malignant cancers threatening human health. The miR-17-92 gene cluster is a highly conserved oncogene cluster encoding 6 miRNAs: miR-17, miR-18a, miR-19a, miR-19b-1, miR-20a and miR-92a. This study explored whether these miRNAs can be used as diagnostic markers for non-small-cell lung cancer (NSCLC).

Methods

Serum samples were collected from healthy subjects (n = 23) and NSCLC patients at various stages (n = 74). Serum RNA was extracted by the TRIzol-glycogen method, and cDNA libraries were constructed by reverse transcription. Quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to detect the expression levels of the 6 miRNAs.

Results

The expression levels of the 6 miRNAs varied in different stages of NSCLC. Thus, 2 receiver operating characteristic (ROC) curves, that is, normal subjects and stage I-III patients and normal subjects and stage IV patients, of each miRNA were established to determine the interval of normal ΔCt values. The 2 areas under the curve (AUCs) of each miRNA were investigated (miR-17: 0.8097 and 1.000; miR-18a: 0.7388 and 0.9907; miR-19a/19b: 0.8451 and 0.5104; miR-20a: 0.8975 and 1.000; miR-92a: 0.8097 and 0.8342). In addition, a high positive correlation was discovered between miR-17 and miR-20a expression. Combining these 2 miRNAs can improve the screening effect of NSCLC.

Conclusion

The miR-17-92 gene cluster can likely serve as a diagnostic marker in NSCLC.

MiR-18a and miR-18b are expressed in the stroma of oestrogen receptor alpha negative breast cancers

BACKGROUND

Previously, we have shown that miR-18a and miR-18b gene expression strongly correlates with high proliferation, oestrogen receptor -negativity (ER^-), cytokeratin 5/6 positivity and basal-like features of breast cancer.

METHODS

We investigated the expression and localization of miR-18a and -18b in formalin fixed paraffin embedded (FFPE) tissue from lymph node negative breast cancers (n = 40), by chromogenic in situ hybridization (CISH). The expression level and in situ localization of miR-18a and -18b was assessed with respect to the presence of tumour infiltrating lymphocytes (TILs) and immunohistochemical markers for ER, CD4, CD8, CD20, CD68, CD138, PAX5 and actin. Furthermore, in two independent breast cancer cohorts (94 and 377 patients) the correlation between miR-18a and -18b expression and the relative quantification of 22 immune cell types obtained from the CIBERSORT tool was assessed.

RESULTS

CISH demonstrated distinct and specific cytoplasmic staining for both miR-18a and miR-18b, particularly in the intratumoural stroma and the stroma surrounding the tumour margin. Staining by immunohistochemistry revealed some degree of overlap of miR-18a and -18b with CD68 (monocytes/macrophages), CD138 (plasma cells) and the presence of high percentages of TILs. CIBERSORT analysis showed a strong correlation between M1-macrophages and CD4+ memory activated T-cells with mir-18a and -18b.

CONCLUSIONS

Our study demonstrates that miR-18a and miR-18b expression is associated with ER- breast tumours that display a high degree of inflammation. This expression is potentially associated specifically with macrophages. These results suggest that miR-18a and miR-18b may play a role in the systemic immunological response in ER^- tumours.

Non-Coding RNAs in Lung Tumor Initiation and Progression

Lung cancer is one of the deadliest forms of cancer affecting society today. Non-coding RNAs, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), through the transcriptional, post-transcriptional, and epigenetic changes they impose, have been found to be dysregulated to affect lung cancer tumorigenesis and metastasis. This review will briefly summarize hallmarks involved in lung cancer initiation and progression. For initiation, these hallmarks include tumor initiating cells, immortalization, activation of oncogenes and inactivation of tumor suppressors. Hallmarks involved in lung cancer progression include metastasis and drug tolerance and resistance. The targeting of these hallmarks with non-coding RNAs can affect vital metabolic and cell signaling pathways, which as a result can potentially have a role in cancerous and pathological processes. By further understanding non-coding RNAs, researchers can work towards diagnoses and treatments to improve early detection and clinical response.

Regulation of PD-1/PD-L1 Pathway in Cancer by Noncoding RNAs

Immune checkpoint blockade has demonstrated significant anti-tumor immunity in an array of cancer types, yet the underlying regulatory mechanism of it is still obscure, and many problems remain to be solved. As an inhibitory costimulatory signal of T-cells, the programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway can paralyze T-cells at the tumor site, enabling the immune escape of tumor cells. Although many antibodies targeting PD-1/PD-L1 have been developed to block their interaction for the treatment of cancer, the reduced response rate and resistance to the therapies call for further comprehension of this pathway in the tumor microenvironment. MicroRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are two main types of noncoding RNAs that play critical parts in the regulation of immune response in tumorigenesis, including the PD-1/PD-L1 pathway. Here we summarize the most recent studies on the control of this pathway by noncoding RNAs in cancer and hopefully will offer new insights into immune checkpoint blockade therapies.

A 5-microRNA signature identified from serum microRNA profiling predicts survival in patients with advanced stage non-small cell lung cancer

Circulating microRNAs (miRNAs) are potential biomarkers for cancer diagnosis, screening and prognosis. This study aimed to identify serum miRNAs as predictors of survival in patients with advanced non-small cell lung cancer (NSCLC). We profiled serum miRNAs in a pilot set of four patients with good survival (>24 months) and four patients with poor survival (<6 months). We selected 140 stably detectable miRNAs and 42 miRNAs reported in literature for further analysis. Expression of these 182 miRNAs was measured using high-throughput polymerase chain reaction assay, and their association with 3-year survival in the discovery (n = 345) and validation (n = 177) cohorts was assessed. Five serum miRNAs (miR-191, miR-28-3p, miR-145, miR-328 and miR-18a) were significantly associated with 3-year overall survival in both cohorts. A combined 5-miRNA risk score was created to assess the cumulative impact of these miRNAs on risk of death. Quartile analysis of the risk score showed significant association with 3-year death risk, with a 4.6-, 6.8- and 9.3-month reduction in median survival time for the second, third and fourth quartiles, respectively. Survival tree analysis also identified distinct risk groups with different 3-year survival durations. Data from The Cancer Genome Atlas revealed all five miRNAs were differentially expressed (P < 0.0001) in paired tumor and normal tissues. Pathway analysis indicated that target genes of these five miRNAs were mainly enriched in inflammatory/immune response pathways and pathways implicated in resistance to chemoradiotherapy and/or targeted therapy. Our results suggested that the 5-miRNA signature could serve as a prognostic predictor in patients with advanced NSCLC.

Long noncoding RNA linc00467 plays an oncogenic role in hepatocellular carcinoma by regulating the miR-18a-5p/NEDD9 axis

Increasing evidence has shown that numerous long noncoding RNAs (lncRNAs) play critical roles in tumorigenesis. Herein, we investigated the biological role of lncRNA linc00467 in the cancer biology of hepatocellular carcinoma (HCC). We observed that linc00467 was upregulated in HCC tissues and cells. Silencing of linc00467 using small interfering RNA interference significantly inhibited the growth and motility of HCC cells, and increased cell apoptosis through regulating the Bcl-2/Bax axis and the caspase cascade, suggesting that linc00467 exerted oncogenic functions in the progression of HCC. Moreover, we found that linc00467 could target miR-18a-5p, and NEDD9 was a target for miR-18a-5p in HCC cells. Furthermore, either the miR-18a-5p inhibitor or upregulation of NEDD9 could recover the inhibitory effects caused by silencing of linc00467. In conclusion, our data highlighted the oncogenic role of linc00467 in HCC progression by regulating the miR-18a-5p/NEDD9 axis.

The dual functional role of MicroRNA-18a (miR-18a) in cancer development

The polycistronic miR-17-92 cluster is instrumental in physiological processes commonly dysregulated in cancer, such as proliferation, the cell cycle, apoptosis, and differentiation. MicroRNA-18a (miR-18a) is one of the most conserved and multifunctional miRNAs in the cluster and is frequently overexpressed in malignant tumors. Altered miR-18a expression has been found in various physiological and pathological processes, including cell proliferation, apoptosis, epithelial-mesenchymal transition (EMT), tumorigenesis, cancer invasion and metastasis. In this review, we summarized the molecular basis and regulatory targets of miR-18a in cancer development. Interestingly, miR-18a has a dual functional role in either promoting or inhibiting oncogenesis in different human cancers. The differential miRNA expression in cancers of the same organ at different stages or of various subtypes suggests that this dual function of miR-18a is independent of cancer type and may be attributed to the fundamental differences in tumorigenic mechanisms. Finally, we summarized the current clinical use of miR-18a and discussed its potential uses in cancer therapy.

Nuclear Factor κB Signaling and Its Related Non-coding RNAs in Cancer Therapy

Nuclear factor κB (NF-κB) acts as a nuclear factor that is composed of five main subunits. It is a pluripotent and crucial dimer transcription factor that has a close relationship with many serious illnesses, especially its influences on cell proliferation, inflammation, and cancer initiation and progression. NF-κB acts as part of the signaling pathway and determines its effect on the expression of several other genes, such as epidermal growth factor receptor (EGFR), p53, signal transducer and activator of transcription 3 (STAT3), and non-coding RNA (ncRNA). Continuous activation of the NF-κB signaling pathway has been seen in many cancer types. While the NF-κB signaling pathway is tightly regulated in physiological settings, quite frequently it is constitutively activated in cancer, and the molecular biology mechanism underlying the deregulated activation of NF-κB signaling remains unclear. In this review, we discuss the regulatory role and possible clinical significance of ncRNA (microRNA [miRNA] and long non-coding RNA [lncRNA]) in NF-κB signaling in cancer, including in the conversion of inflammation to carcinogenesis. Non-coding RNA plays an essential and complex role in the NF-κB signaling pathway. NF-κB activation can also induce the ncRNA status. Targeting NF-κB signaling by ncRNA is becoming a promising strategy of drug development and cancer treatment.

TCPA v3.0: An Integrative Platform to Explore the Pan-Cancer Analysis of Functional Proteomic Data

Reverse-phase protein arrays represent a powerful functional proteomics approach to characterizing cell signaling pathways and understanding their effects on cancer development. Using this platform, we have characterized ∼8,000 patient samples of 32 cancer types through The Cancer Genome Atlas and built a widely used, open-access bioinformatic resource, The Cancer Proteome Atlas (TCPA). To maximize the utility of TCPA, we have developed a new module called "TCGA Pan-Cancer Analysis," which provides comprehensive protein-centric analyses that integrate protein expression data and other TCGA data across cancer types. We further demonstrate the value of this module by examining the correlations of RPPA proteins with significantly mutated genes, assessing the predictive power of somatic copy-number alterations, DNA methylation, and mRNA on protein expression, inferring the regulatory effects of miRNAs on protein expression, constructing a co-expression network of proteins and pathways, and identifying clinically relevant protein markers. This upgraded TCPA (v3.0) will provide the cancer research community with a more powerful tool for studying functional proteomics and making translational impacts.

Detection of circulating exosomal miR-17-5p serves as a novel non-invasive diagnostic marker for non-small cell lung cancer patients

Exosome-shuttled bioactive miRNAs act as novel non-invasive biomarkers for cancer diagnosis have received increasing attention. In this study, we aimed to investigate the expression signatures of exosomal miRNAs and develop a serum exosome-derived miRNA panel for diagnosis of non-small cell lung cancer (NSCLC). The miR-17-92 cluster including 6 miRNAs (miR-17-5p, miR-18a-5p, miR-19a-3p, miR-19b-1-5p, miR-20a-5p and miR-92a-1-5p) was selected as potential diagnostic candidate molecule. Then, expression profiles of the candidate miRNAs were firstly analyzed in 43 pairs of serum samples from the training set by quantitative real-time PCR, and the dysregulated miRNA along with three tumor markers (carcinoembryonic antigen, CEA; cytokeratin 19 fragment, CYFRA21-1; squamous cell carcinoma antigen, SCCA) were further validated in two independent cohorts, which consisted of training set (including 100 NSCLC patients and 90 healthy controls) and validation set (including 72 NSCLC patients and 47 healthy controls). The expression of miR-17-5p was significantly up-regulated in NSCLC patients compared with the healthy controls (P < 0.001), suggesting that miR-17-5p might have considerable clinical value in the diagnosis of NSCLC. Based on the data from the training set, we next used a logistic regression model to construct a 4-molecule panel consisting of miR-17-5p and three tumor markers for NSCLC diagnosis. The performance of such 4-molecule panel was verified with an area under the ROC curve of 0.860 (95% CI = 0.802 to 0.906, sensitivity = 63.0% and specificity = 93.3%) and 0.844 (95% CI = 0.766 to 0.904, sensitivity = 76.4% and specificity = 76.6%) in the training set and validation set, respectively. In conclusion, the newly developed diagnostic panel consisting of exosomal miR-17-5p, CEA, CYFRA21-1 and SCCA may have considerable clinical value in the diagnosis of NSCLC.

MicroRNA-664 functions as an oncogene in cutaneous squamous cell carcinomas (cSCC) via suppressing interferon regulatory factor 2

BACKGROUND

Aberrant expression of microRNA-664 was involved in tumor growth and metastasis of various cancers. The specific role of miR-664 in cutaneous squamous cell carcinoma (cSCC) is yet to be elucidated.

OBJECTIVE

The present study aimed to investigate the molecular mechanisms underpinning of cSCC development and provide translational insights for future therapeutics.

METHODS

Human cSCC specimens were used to determine the miR-664 by in situhybridization and IRF2 by immunohistochemistry. To study the potential mechanisms in tumorigenesis, three cSCC cell lines including HSC-5, HSC-1 and A431 as well as BALB/C mouse tumor model was utilized.

RESULTS

We found that miR-664 was remarkably high in cSCC patient specimens and cSCC cell lines. Overexpression of miR-664 promotes tumorigenic behaviors such as increased cell proliferation, migration and invasion capacities in vitro and enhanced tumorigenicity in xenograft mouse model. Our data further identified IRF2 as a direct downstream target of miR-664. Knockdown of IRF2 reverses pro-tumorigenesis phenotype of miR-664; whereas IRF2 over-expression inhibits miR-664 tumorigenesis in cSCC. Together, it revealed miR-664 functions as an oncogene in cSCC via suppression of IRF2.

CONCLUSION

Our data demonstrates that aberrant expression of miR-664 plays a critical role in carcinogenesis of cSCC. The discovery of novel targets such as miR-664 and IRF2 will facilitate future development of therapeutic interventions.

Enhanced Inhibition of Tumorigenesis Using Combinations of miRNA-Targeted Therapeutics

The search for effective strategies to inhibit tumorigenesis remains one of the most relevant scientific challenges. Among the most promising approaches is the direct modulation of the function of short non-coding RNAs, particularly miRNAs. These molecules are propitious targets for anticancer therapy, since they perform key regulatory roles in a variety of signaling cascades related to cell proliferation, apoptosis, migration, and invasion. The development of pathological states is often associated with deregulation of miRNA expression. The present review describes in detail the strategies aimed at modulating miRNA activity that invoke antisense oligonucleotide construction, such as small RNA zippers, miRNases (miRNA-targeted artificial ribonucleases), miRNA sponges, miRNA masks, anti-miRNA oligonucleotides, and synthetic miRNA mimics. The broad impact of developed miRNA-based therapeutics on the various events of tumorigenesis is also discussed. Above all, the focus of this review is to evaluate the results of the combined application of different miRNA-based agents and chemotherapeutic drugs for the inhibition of tumor development. Many studies indicate a considerable increase in the efficacy of anticancer therapy as a result of additive or synergistic effects of simultaneously applied therapies. Different drug combinations, such as a cocktail of antisense oligonucleotides or multipotent miRNA sponges directed at several oncogenic microRNAs belonging to the same/different miRNA families, a mixture of anti-miRNA oligonucleotides and cytostatic drugs, and a combination of synthetic miRNA mimics, have a more complex and profound effect on the various events of tumorigenesis as compared with treatment with a single miRNA-based agent or chemotherapeutic drug. These data provide strong evidence that the simultaneous application of several distinct strategies aimed at suppressing different cellular processes linked to tumorigenesis is a promising approach for cancer therapy.

Screening of key miRNAs and evaluation of their diagnostic and prognostic values in nasopharyngeal carcinoma

Increasing evidence has revealed the importance of microRNA (miRNA/miR) in cancer genesis and progression. The aim of the current study was to identify the key miRNAs involved in the onset and development of nasopharyngeal carcinoma (NPC) and to further evaluate their diagnostic and prognostic values. Microarray data were obtained and analyzed to screen differentially expressed miRNAs (DEMs) between patients with NPC and healthy controls. The target genes of the DEMs were predicted and their possible functions were evaluated. The diagnostic and prognostic values of the DEMs were subsequently investigated. A total of 4 DEMs, including miR-18a, miR-135b, miR-204 and miR-497, were identified. Gene Ontology (GO) and pathway enrichment analysis revealed that the target genes were enriched in a number of GO terms and signaling pathways. The results demonstrated that the selected DEMs may present potential diagnostic factors for NPC. In addition, miR-18a [Hazard ratio (HR), 3.405; 95% confidence interval (CI), 1.334-8.693] and miR-135b (HR, 2.482; 95% CI, 1.014-6.076) may serve prognostic roles for patients with NPC. In summary, the present study identified 4 miRNAs that may be involved in the genesis and development of NPC. In addition, miR-18a and miR-135b may present useful prognostic markers for patients with NPC. Future in vitro and in vivo investigations are warranted to substantiate the results obtained in the current study.

Rapamycin- and starvation-induced autophagy are associated with miRNA dysregulation in A549 cells

MicroRNAs (miRNAs) are short (20-23 nt) non-coding RNAs that are involved in post-transcriptional regulation of gene expression in multicellular organisms by affecting both the stability and translation of mRNAs. In recent years, deep sequencing of the transcription is being increasingly utilized with the promise of higher sensitivity for the identification of differential expression patterns as well as the opportunity to discover new transcripts, including new alternative isoforms and miRNAs. In this study, miRNAs from A549 cells treated with/without rapamycin or starvation were subject to genome-wide deep sequencing. A total of 1534 miRNAs were detected from the rapamycin- and starvation-treated A549 cells. Among them, 31 miRNAs were consistently upregulated and 131 miRNAs were downregulated in the treated cells when compared with the untreated cells. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis of the predicted target genes of the most significantly differentially expressed miRNAs revealed that the autophagy-related miRNAs are involved in cancer pathway. Taken together, our findings indicate that the underlying mechanism responsible for autophagy is associated with dysregulation of miRNAs in rapamycin- or starvation-induced A549 cells.

WITHDRAWN: MicroRNA-18a promotes proliferation and metastasis in oral squamous cell carcinoma via targeting KLF4

Ahead of Print article withdrawn by publisher.

MicroRNA-296, a suppressor non-coding RNA, downregulates SGLT2 expression in lung cancer

Non-small cell lung cancer (NSCLC) is one of the most common types of cancer worldwide and has the highest mortality rate in China. MicroRNAs (miRNAs or miRs) are involved in tumorigenesis and their important role in cancer is becoming increasingly apparent. The expression of miR‑296‑5p in particular has been shown to be significantly downregulated in lung cancer. Sodium-glucose co-transporter-2 [SGLT2, also known as solute carrier family 5 member 2 (SLC5A2)] is an oncogene that promotes tumorigenesis. In this study, we aimed to determine the role of miR‑296‑5p in lung cancer and whether this involves the targeting of SGLT2. For this purpose, we examined miR‑296‑5p and SGLT2 expression in human lung cancer samples and cell lines by RT-qPCR and western blot analysis. In addition, the data analysis website TCGA was used for survival analysis with respect to SGLT2 expression. The effects of miR‑296‑5p were also examined on cell proliferation and cell cycle progression using respective assays. The results demonstrate that miR‑296‑5p is significantly downregulated in NSCLC tissues. Additionally, it is demonstrated that SGLT2 is directly targeted by miR‑296‑5p. Furthermore, our data reveal that the knockdown of SGLT2 using siRNA inhibits cell proliferation and impedes cell cycle progression. Collectively, data suggest that miR‑296‑5p not only inhibits NSCLC by downregulating SGLT2 expression, but also acts as a novel regulator of aberrant lung cancer cells to limit lung cancer progression.

IDO1 impairs NK cell cytotoxicity by decreasing NKG2D/NKG2DLs via promoting miR-18a

BACKGROUND

Indoleamine-2,3-dioxygenase 1 (IDO1) is an important enzyme for altering the tumour microenvironment and assisting tumour cells to escape the immune system.

RESULTS

In this study, a significant reduction in NK cell cytotoxicity that was associated with a high expression of IDO1 in a reconstructed tumour microenvironment was observed. In a co-culture system of tumour cell culture supernatant (TSN) and murine NK cell, IDO1 was substantially increased, while NKG2D was markedly downregulated in NK cells. Based on computational predictions, miR-18a, which has two definite binding sites consisting of the 3'UTR of NKG2D and the 3'UTR of NKG2D ligand (Mult-1), was suspected to be a negative regulator of which its conjoined. As expected, the IDO1 could promote the expression of miR-18a and promote the downregulation effect of miR-18a on NKG2D and NKG2DL, and INCB024360 (INCB) could reverse the result. For digging the mechanism deeper, we authenticated IDO1 promoted the combination of miR-18a and AGO2 after argonaute 2 (AGO2) co-immunoprecipitation, which then degraded Mult-1 mRNA and inhibited the translation of it, further destructing NK cell cytotoxicity.

CONCLUSION

Our findings revealed a new regulatory axis, IDO1/miR-18a/NKG2D/NKG2DL, in the regulation of NK cell function. This may provide insight into the mechanism of the priming effect of IDO1 inhibitors and miR-18a interference, then elicit possible new methods of cancer treatment.

Regulation of proto-oncogene Orai3 by miR18a/b and miR34a

Store Operated Ca²⁺ Entry (SOCE) mediated by Orai channels is a ubiquitous Ca²⁺ influx pathway that regulates several cellular functions. We have earlier reported that Orai3, the mammalian specific Orai1 homolog, plays a critical role in breast cancer progression. More recently, Orai3 was demonstrated to regulate prostate and lung tumorigenesis. Although the tumorigenic potential of Orai3 is associated with increase in its expression, the molecular machinery regulating its expression remains largely unexplored. Here, by performing extensive bioinformatics analysis and functional studies, we identify and characterize micro-RNAs (miRNAs) that regulate Orai3 expression and function. We demonstrate that miR18a and miR18b positively regulate Orai3 whereas miR34a represses Orai3 expression and function. All these miRs exert their effect on Orai3 by virtue of their direct action on Orai3 3'UTR. These miRs provide novel opportunities for targeting Orai3 for better management of cancer. This study further opens up the possibility of targeting specific Orai homologs by different miRs in tissue and disease specific context.

MicroRNA-1258 suppresses tumour progression via GRB2/Ras/Erk pathway in non-small-cell lung cancer

OBJECTIVES

Lung cancer is still a disease with high morbidity and mortality in the world. MicroRNAs have been proven to act as an indispensable role in the reuse of multiple solid tumours. Although miR-1258 plays a vital role in suppressing metastasis in breast cancer and gastric cancer, the specific biological function of miR-1258 in non-small-cell lung cancer remains unclear.

METHODS

The differential expression of miR-1258 in NSCLC tissues and corresponding paracancerous tissues was detected by qRT-PCR and ISH. Flow cytometry and CCK-8, EdU, tubule formation, and senescence assays were performed, and xenograft models were studied to explore the function of miR-1258. Potential targets of miR-1258 were verified by dual luciferase reporter assay, qRT-PCR, IHC and Western blotting.

RESULTS

In vitro and in vivo gain- and loss-of-function assays suggested that miR-1258 inhibits NSCLC cell proliferation and induces senescence and apoptosis. The luciferase reporter assay, IHC and Western blotting analysis showed that GRB2 is one of the direct targets of miR-1258. The GRB2 overexpression plasmid can reverse the functional changes after overexpression of miR-1258. In contrast, miR-1258 inhibitor significantly reversed si-GRB2-induced GRB2 down-regulation. Mechanistically, overexpression of miR-1258 inhibits GRB2 expression and then leads to inactivation of the Ras/Erk oncogenic pathway.

CONCLUSIONS

Our results indicate that miR-1258 can suppress NSCLC progression by targeting the GRB2/Ras/Erk pathway, which may lead to different insights into potential biomarkers and novel therapeutic strategies for NSCLC patients.

miR-18a-5p promotes cell invasion and migration of osteosarcoma by directly targeting IRF2

An increasing number of studies have suggested that microRNAs (miRNAs) are involved in the progress of many human cancers including osteosarcoma (OS). Especially, microRNA-18a-5p (miR-18a-5p) has been reported to associate with the occurrence, development and clinical outcomes of human cancers. Therefore, we investigated the functions of miR-18a-5p in OS. Reverse transcription-quantitative PCR (RT-qPCR) showed that miR-18a-5p was significantly upregulated in OS tissues and cell lines (MG-63 and Saos-2). The overexpression of miR-18a-5p was found to significantly promote cell migration and invasion in MG-63 cells via Transwell assay. Moreover, luciferase reporter assays indicated that interferon regulatory factor (IRF)2 was a direct target of miR-18a-5p. IRF2 was downregulated in MG-63 and Saos-2 cell lines. Furthermore, Transwell analysis showed that the knockout of IRF2 promoted cell migration and invasion in MG-63 cells. Carcinogenesis of miR-18a-5p was reversed by the overexpression of IRF2 in OS. In conclusion, miR-18a-5p promoted the invasion and migration of OS cells through inhibiting IRF2 expression. Thus, miR-18a-5p might act as a potential target for the diagnosis and treatment of OS in the future.

The long noncoding RNA GAS5 negatively regulates the adipogenic differentiation of MSCs by modulating the miR-18a/CTGF axis as a ceRNA

Mesenchymal stem cells (MSCs) are important pluripotent stem cells and a major source of adipocytes in the body. However, the mechanism of adipogenic differentiation has not yet been completely elucidated. In this study, the long noncoding RNA GAS5 was found to be negatively correlated with MSC adipogenic differentiation. GAS5 overexpression negatively regulated adipocyte formation, whereas GAS5 knockdown had the opposite effect. Further mechanistic analyses using luciferase reporter assays revealed that GAS5 regulates the adipogenic differentiation of MSCs by acting as competing endogenous RNA (ceRNA) to sponge miR-18a, which promotes adipogenic differentiation. Mutation of the binding sites for GAS5 in miR-18a abolished the effect of the interaction. The miR-18a mimic and inhibitor reversed the negative regulatory effect of GAS5 on MSCs adipogenic differentiation. In addition, GAS5 inhibited miR-18a, which downregulates connective tissue growth factor (CTGF) expression, to negatively regulate the adipogenic differentiation of MSCs. Taken together, the results show that GAS5 serves as a sponge for miR-18a, inhibiting its capability to suppress CTGF protein translation and ultimately decreasing the adipogenic differentiation of MSCs. GAS5 is an important molecule involved in the adipogenic differentiation of MSCs and may contribute to the functional regulation and clinical applications of MSCs.

TP53TG1 enhances cisplatin sensitivity of non-small cell lung cancer cells through regulating miR-18a/PTEN axis

Background

The acquisition of drug resistance has been considered as a main obstacle for cancer chemotherapy. Tumor protein 53 target gene 1 (TP53TG1), a p53-induced lncRNA, plays a vital role in the progression of human cancers. However, little is known about the detailed function and molecular mechanism of TP53TG1 in cisplatin resistance of NSCLC.

Methods

qRT-PCR analysis was used to detect the expression of TP53TG1, miR-18a and PTEN mRNA in NSCLC tissues and cells. Western blot analysis was performed to determine the protein level of PTEN and cleaved caspase-3. Cell viability and IC50 value were measured by MTT assay. Cell apoptosis was confirmed by flow cytometry assay. Subcellular fractionation assay was used to identify the subcellular location of TP53TG1. Dual-luciferase reporter assay, RNA pull down assay and RNA immunoprecipitation assay were carried out to verify the interaction between TP53TG1 and miR-18a. Xenografts in nude mice were established to verify the effect of TP53TG1 on cisplatin sensitivity of NSCLC cells in vivo.

Results

TP53TG1 level was downregulated in NSCLC tissues and cell lines. Upregulated TP53TG1 enhanced cisplatin sensitivity and apoptosis of A549/DDP cells, while TP53TG1 depletion inhibited cisplatin sensitivity and apoptosis of A549 cells. TP53TG1 suppressed miR-18a expression in A549 cells. Moreover, TP53TG1-mediated enhancement effect on cisplatin sensitivity was abated following the restoration of miR-18a expression in A549/DDP cells, while si-TP53TG1-induced decrease of cisplatin sensitivity and apoptosis was counteracted by miR-18a inhibitor in A549 cells. Furthermore, TP53TG1 promoted PTEN expression via inhibiting miR-18a. Finally, TP53TG1 sensitized NSCLC cells to cisplatin in vivo.

Conclusion

TP53TG1 increased the sensitivity of NSCLC cells to cisplatin by modulating miR-18a/PTEN axis, elucidating a novel approach to boost the effectiveness of chemotherapy for NSCLC.

Electronic supplementary material

The online version of this article (10.1186/s13578-018-0221-7) contains supplementary material, which is available to authorized users.

Long non-coding RNA FENDRR reduces prostate cancer malignancy by competitively binding miR-18a-5p with RUNX1

CONTEXT

Prostate cancer (PCa) is one of the most commonly diagnosed malignancy in men in the western world.

OBJECTIVE

We aim to investigate the biological role of long non-coding RNA FENDRR and its mechanism in PCa.

MATERIALS AND METHODS

We determined the expression of FENDRR and miR-18a-5p in PCa tissues and examined the regulatory mechanism in PCa cell lines.

RESULTS

FENDRR transcripts in human PCa tissues were significantly decreased compared with the normal controls. Reduced expression of FENDRR was correlated with the increase of pathological degree and poor prognosis in PCa patients. Upregulation of FENDRR inhibited cell proliferation, increased apoptosis and decreased invasion and migration ability, which was inhibited by miR-18a-5p mimic. Knockdown of FENDRR resulted in a significant increase of PCa cell proliferation and decrease of apoptosis and this effect was inhibited miR-18a-5p inhibitor. FENDRR and RUNX1 contain potential target sites for miR-18a-5p. miR-18a-5p mimic inhibited RUNX1 expression and luciferase activity. FENDRR could increase RUNX1 expression, which was inhibited by miR-18a-5p. The effect of FENDRR on cell proliferation, apoptosis and invasion and migration ability was suppressed by silence of RUNX1.

DISCUSSION AND CONCLUSION

These results position FENDRR/miR-18a-5p/RUNX1 as a potential therapeutic target and biomarker for PCa.

MicroRNA-134-5p promotes high glucose-induced podocyte apoptosis by targeting bcl-2

Podocyte apoptosis is a typical early feature of diabetic nephropathy (DN), with loss of nephrin integrity contributing to increased proteinuria in patients with DN. Emerging evidence shows that microRNAs (miRNAs) play vital roles in the pathogenesis of DN. Thus, we aimed to further elucidate the role of miRNAs in podocyte apoptosis in DN. We used db/db and db/m mice maintained under a continuous feeding regime for 12 weeks. Using microarray analysis, we found several miRNAs potentially related to podocyte apoptosis. In addition, we cultured a conditionally immortalized human podocyte cell line in 30 mM D-glucose and found that miR-134-5p was upregulated in both db/db mice and high-glucose (HG)-treated podocytes. Upregulation of miR-134-5p was accompanied by podocyte apoptosis and downregulation of nephrin. Inhibition of miR-134-5p produced the opposite effect. Dual-luciferase reporter assays showed that miR-134-5p directly targeted the 3'-untranslated region of the B-cell lymphoma-2 gene (BCL2), and further study confirmed an increase in bcl-2 protein level in HG-treated podocytes transfected with anti-miR-134-5p. Knockdown of BCL2 impeded the antiapoptotic effect of anti-miR-134-5p. Finally, we found that miR-134-5p might regulate apoptosis in db/db mice and podocytes by targeting BCL2. Taken together, our findings suggest that miR-134-5p promotes podocyte apoptosis under HG conditions by targeting BCL2. Our study provides a meaningful approach to interpret the mechanisms of action of miRNAs involved in DN.

MicroRNA-1253 suppresses cell proliferation and invasion of non-small-cell lung carcinoma by targeting WNT5A

MicroRNAs (miRNA) are a class of small, noncoding RNA molecules that regulate the expression of target genes. miRNA dysregulation is involved in carcinogenesis and tumor progression. In this study, we identified microRNA-1253 (miR-1253) as being significantly down-regulated in non-small-cell lung carcinoma (NSCLC) tissues and associated with advanced clinical stage, lymph node metastasis, and poor survival. The enhanced expression of miR-1253 significantly inhibited the proliferation, migration, and invasion of NSCLC cells in vitro. Bioinformatics analyses showed that miR-1253 directly targeted WNT5A (long isoform), which was confirmed using the dual-luciferase reporter assay. The inhibitory effects of miR-1253 on the growth and metastasis of NSCLC cells were attenuated and phenocopied by WNT5A (long) overexpression and knockdown, respectively. Consistent with the in vitro results, subcutaneous tumor and metastatic NSCLC mouse models showed that miR-1253 functions as a potent suppressor of NSCLC in vivo. Taken together, our findings indicated that miR-1253 inhibited the proliferation and metastasis of NSCLC cells by targeting WNT5A (long isoform) and provided new evidence of miR-1253 as a potential therapeutic target in NSCLC.

mTOR signaling-related MicroRNAs and Cancer involvement

MicroRNAs (miRNAs) are a class of single-stranded RNAs, 18-23 nucleotides in length that regulate gene expression at the post-transcriptional level. Dysregulation of miRNAs has been closely associated with the development of cancer. In the process of tumorigenesis, mammalian target of rapamycin (mTOR) plays important roles, and the mTOR signaling pathway is aberrant in various types of human cancers, including non-small cell lung cancer (NSCLC), breast cancer, prostate cancer, as well as others. However, the relationship between miRNAs and the mTOR signaling pathway is indistinct. Herein, we not only summarize the progress of miRNAs and the mTOR signaling pathway in cancers, but also highlight their role in the diagnosis and treatment in the clinic.

Biology of MiR-17-92 Cluster and Its Progress in Lung Cancer

MicroRNAs, a class of short endogenous RNAs, acting as post-transcriptional regulators of gene expression, mostly silence gene expression via binding imperfectly matched sequences in the 3'UTR of target mRNA. MiR-17-92, a highly conserved gene cluster, has 6 members including miR-17, miR-18a, miR-19a, miR-20a, miR-19b-1 and miR-92a. The miR-17-92 cluster, regarded as oncogene, is overexpressed in human cancers. Lung cancer is the leading cause of death all over the world. The molecular mechanism of lung cancer has been partly known at the levels of genes and proteins in last decade. However, new prognosis biomarkers and more target drugs should be developed in future. Therefore, noncoding RNAs, especially miRNAs, make them as new potentially clinical biomarkers for diagnosis and prognosis. In this review, we focus the current progress of miR-17-92 cluster in lung cancer.

Long non-coding RNA CASC2 enhanced cisplatin-induced viability inhibition of non-small cell lung cancer cells by regulating the PTEN/PI3K/Akt pathway through down-regulation of miR-18a and miR-21

Long non-coding RNA cancer susceptibility candidate 2 (lncRNA CASC2) is a tumor suppressor and has been proved to contribute to chemotherapy efficacy. However, the effect of CASC2 on cisplatin cytotoxicity in non-small cell lung cancer (NSCLC) is unclear. The present study aimed to investigate the role of CASC2 in regulating cisplatin cytotoxicity in NSCLC cells. Herein, we found that CASC2 was low-expressed, while miR-18a and miR-21 were over-expressed in NSCLC cell lines. CASC2 enhanced the inhibition effect of cisplatin on cell viability. Down-regulation of miR-18a and miR-21 exhibited the similar effect to CASC2 and mimics of miR-18a and miR-21 displayed the opposite effect to CASC2. MiR-18a and miR-21 were two targets of CASC2 in NSCLC. PTEN was found to be a target of miR-18a and miR-21 in NSCLC. CASC2 overexpression increased PTEN expression level and reduced the ratio of p-Akt/Akt. MiR-18a or miR-21 mimics attenuated the effect of CASC2 overexpression on the PTEN expression and ratio of p-Akt/Akt. The results suggested that CASC2 enhanced cisplatin-induced viability inhibition of NSCLC cells via PTEN/PI3K/Akt pathway through suppressing miR-18a and miR-21 expression.

Long non-coding RNA cancer susceptibility candidate 2 (lncRNA CASC2) is a tumor suppressor and has been proved to contribute to chemotherapy efficacy.

Overexpression of miR-1290 contributes to cell proliferation and invasion of non small cell lung cancer by targeting interferon regulatory factor 2

MicroRNAs are small endogenous non-coding RNAs, which can frequently emerge as regulators in many cancer types. MiR-1290 was found to be abnormally elevated in non small cell lung cancer (NSCLC). However, the underlying molecular mechanism still needs to be investigated. Here, we demonstrated that miR-1290 expression levels were remarkably upregulated in NSCLC tissues compared to adjacent normal tissues. Higher miR-1290 expression levels positively associated with lymph node metastasis and advanced tumor stage. Functional assays showed that upregulated miR-1290 expression in NSCLC cells enhanced cell proliferation, cell colony formation and invasion capacities in vitro. Furthermore, we found that miR-1290 promoted cell proliferation related protein CDK2 and CDK4 expression and enhanced Epithelial-Mesenchymal Transition (EMT) process by downregulating E-cadherin expression and upregulating N-cadherin expression. Bioinformatics analysis and luciferase reporter gene assays revealed that Interferon regulatory factor 2 (IRF2) was a direct target of miR-1290. Overexpression of miR-1290 can degrade IRF2 mRNA and downregulated IRF2 protein expression in NSCLC cells. Upregulated IRF2 could partly rescue the promoting effects induced by miR-1290 overexpression on cell proliferation and invasion of NSCLC. Additionally, we confirmed that reduced miR-1290 expression could suppress tumor growth using a tumor xenograft model in vivo. Thus, we concluded that miR-1290 may serve as a potential target of NSCLC treatment.

MicroRNA-381 inhibits cell proliferation and invasion in endometrial carcinoma by targeting the IGF-1R

Endometrial carcinoma (EC) is the sixth most common type of malignant tumor occurring in females. MicroRNAs (miRNAs) serve as oncogenes or tumor suppressors in human cancer and play important roles in tumorigenesis, and tumor development by regulating various processes. Thus, further investigation into miRNAs involved in EC formation and progression may aid in developing effective therapeutic strategies for patients with this disease. miRNA‑381 (miR‑381) is aberrantly expressed in multiple types of human cancer. However, the expression pattern, biological roles and underlying mechanisms of miR‑381 in EC are poorly understood. In the present study, the results showed that miR‑381 was downregulated in EC tissues and cell lines. Decreased miR‑381 expression correlated with the International Federation of Gynecology and Obstetrics stage, lymph nodes metastasis and myometrial invasion of EC. The ectopic expression of miR‑381 significantly inhibited the proliferation and invasion of EC cells. Through a series of experiments, the insulin‑like growth factor receptor 1 (IGF‑1R) was identified as a novel direct target of miR‑381 in EC. Furthermore, IGF‑1R was highly expressed in EC tissues and inversely correlated with miR‑381 levels. IGF‑1R overexpression partially abrogated the tumor‑suppressive effects of miR‑381 on the proliferation and invasion of EC cells. miR‑381 targeted IGF‑1R to inactivate the protein kinase B (AKT) and extracellular signal‑regulated kinase (ERK) signaling pathways in EC. These results suggest that miR‑381 acts as a tumor suppressor in EC by directly targeting IGF‑1R, and indirectly regulating the AKT and ERK signaling pathways. Thus, miR‑381 should be investigated as a prognostic biomarker and novel therapeutic target for the treatment of patients with EC.

α, γ-Mangostins Induce Autophagy and Show Synergistic Effect with Gemcitabine in Pancreatic Cancer Cell Lines

Pancreatic cancer is one of the most lethal and aggressive cancers in the world. However, no effective treatment is currently available for pancreatic cancer. The objective of this study was to determine the anti-pancreatic cancer effect of α-mangostin (αM) and γ-mangostin (γM) extracted from the pericarp of Garcinia mangostana L.. Both αM and γM reduced the viability of pancreatic cancer cells MIA PaCa-2 and PANC-1 in a dose-dependent manner. These compounds induced apoptosis by increasing c-PARP and c-Caspase 3 levels. They also induced autophagy by increasing levels of microtubule-associated protein 1A/1B light chain 3B (LC3II) in both cell lines while decreasing sequestosome 1 (p62) in MIA PaCa-2. Both αM and γM induced autophagy through increasing phosphorylation levels of AMP-activated protein kinase (p-AMPK) and p38-mitogen activated protein kinase (p-p38) while decreasing phosphorylation level of mammalian target of rapamycin complex 1 (p-mTOR). Of various microRNAs (miRNA), miR-18a was found to be a putative regulatory miRNA for autophagy induced by αM or γM. In combination with gemcitabine, a compound frequently used in pancreatic cancer treatment, αM and γM showed synergistic anti-cancer effects in MIA PaCa-2. Collectively, these results suggest that αM and γM can induce apoptosis and autophagy in pancreatic cancer cells and that their anti-cancer effect is likely to be associated with miR-18a. In conclusion, αM and γM might be used as a potential new therapy for pancreatic cancer.

IsomiR processing during differentiation of myelogenous leukemic cell line K562 by phorbol ester PMA

Chronic myelocytic leukemia cell line K562 undergoes differentiation by phorbol esters to megakaryocytes and we have used this system to understand miRNA processing leading to isomiR generation. PMA treatment significantly altered the production of miRNA in K562 cells. Expression of 24.4% of miRNAs were found to be stimulated whereas expression of 10% miRNAs were inhibited by PMA treatment. Our results suggest that miRNA precursors are processed into isomiRs in a deterministic manner. The relative levels of different isomiRs of a miRNA remained mainly unchanged even after PMA treatment irrespective of overall changes in expression (either up-regulation or down-regulation). However, not all miRNAs behave in the same way, about 7% showed a variation of isomiR profiles after PMA treatment. Most of the later class of miRNAs were found to be oncogenic miRNAs. Further, it was also found that number of isomiRs was independent of abundance of a miRNA. Functional importance of different isomiRs was demonstrated using three different isomiRs of miR-22. Our results showed that different isomiRs could inhibit expression of targets genes with different efficiencies. Our study suggests that the heterogeneity of a miRNA population generated during processing is in general regulated and that variation in the generation of an isomiR can be a functionally important regulatory feature.

MicroRNA-219 is downregulated in non-small cell lung cancer and inhibits cell growth and metastasis by targeting HMGA2

Lung cancer is the most commonly diagnosed cancer and the leading cause of cancer-associated mortality worldwide. Non-small cell lung cancer (NSCLC) is the predominant type of lung cancer, and accounts for ~85% of all lung cancer cases. An increasing number of studies suggest that microRNAs (miRs) may be involved in the regulation of NSCLC carcinogenesis and progression. However, the expression and function of miRNA-219 in NSCLC, and its underlying mechanisms of action, remain unknown. In the present study, miR-219 expression in NSCLC tissues and cell lines was determined using reverse transcription-quantitative polymerase chain reaction. Following transfection with miR-219 mimics, the effects of miR-219 overexpression on NSCLC cell proliferation, migration and invasion were examined. Furthermore, the miR-219 target in NSCLC was investigated. miR-219 was observed to be downregulated in NSCLC tissues and NSCLC cell lines. In addition, miR-219 was demonstrated to function as a tumor suppressor in NSCLC, through inhibiting cell proliferation, migration and invasion in vitro. Furthermore, high mobility group AT-hook 2 (HMGA2) was identified to be a direct target of miR-219 in NSCLC, and downregulation of HMGA2 suppressed NSCLC cell proliferation, migration and invasion in vitro. HMGA2 expression was upregulated in NSCLC tissues, and was inversely correlated with miR-219 expression. In conclusion, miR-219 functions as a tumor suppressor and may be important in inhibiting the growth and metastasis of NSCLC cells via directly targeting HMGA2. Therefore, miR-219 may present a potential novel therapeutic target for NSCLC.

MicroRNA‑503 serves an oncogenic role in laryngeal squamous cell carcinoma via targeting programmed cell death protein 4

Laryngeal squamous cell carcinoma (LSCC), the most common form of laryngeal carcinoma, is an aggressive malignancy that demonstrates the second highest rate of morbidity of all head and neck squamous cell carcinomas. The abnormal expression of microRNAs (miRs) has been demonstrated in a number of types of human cancer, and they have been demonstrated to be oncogenes or tumour suppressor genes. miR-503 has been studied in various types of human cancer; however, the expression level, roles and underlying mechanisms in LSCC remain unknown. In the present study, it was demonstrated that miR-503 was significantly upregulated in LSCC tissues and cell lines. The level of miR-503 in LSCC tissues was correlated with thyroid cartilage invasion, lymph node metastasis, and tumour, node and metastasis stage. In addition, down-regulation of miR-503 inhibited cell proliferation and invasion in LSCC. Programmed cell death protein 4 (PDCD4) was identified to be a direct target gene of miR-503. PDCD4 overexpression could mimic the roles of miR-503 underexpression in LSCC. Furthermore, PDCD4 was down-regulated in LSCC tissues and this correlated with the miR-503 expression level. In conclusion, these results suggested that miR-503 promotes tumour growth and invasion by directly targeting PDCD4. The identification of the miR-503/PDCD4 axis may provide novel targets for LSCC treatment and improve prognosis.