MiR-424 functions as a tumor suppressor in glioma cells and is down-regulated by DNA methylation

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

Synergistic Effects of A Combined Treatment of Glioblastoma U251 Cells with An Anti-miR-10b-5p Molecule and An AntiCancer Agent Based on 1-(3',4',5'-Trimethoxyphenyl)-2-Aryl-1H-Imidazole Scaffold

(1) Background: In the development of new and more effective anticancer approaches, combined treatments appear of great interest. Combination therapy could be of importance in the management of glioblastoma (GBM), a lethal malignancy that accounts for 42% of cancer of the central nervous system, with a median survival of 15 months. This study aimed to verify the activity on a glioblastoma cancer cell line of one of the most active compounds of a novel series of tubulin polymerization inhibitors based on the 1-(3′,4′,5′-trimethoxyphenyl)-2-aryl-1H-imidazole scaffold, used in combination with a miRNA inhibitor molecule targeting the oncomiRNA miR-10b-5p. This microRNA was selected in consideration of the role of miR-10b-5p on the onset and progression of glioblastoma. (2) Methods: Apoptosis was analyzed by Annexin-V and Caspase 3/7 assays, efficacy of the anti-miR-10b-5p was assessed by determining the miR-10b-5p content by RT-qPCR. (3) Results: The results obtained show that a “combination therapy” performed by combining the use of an anti-miR-10b-5p and a 1-(3′,4′,5′-trimethoxyphenyl)-2-aryl-1H-imidazole derivative is an encouraging strategy to boost the efficacy of anticancer therapies and at the same time to reduce side effects.

A microRNA Cluster Controls Fat Cell Differentiation and Adipose Tissue Expansion By Regulating SNCG

The H19X-encoded miR-424(322)/503 cluster regulates multiple cellular functions. Here, it is reported for the first time that it is also a critical linchpin of fat mass expansion. Deletion of this miRNA cluster in mice results in obesity, while increasing the pool of early adipocyte progenitors and hypertrophied adipocytes. Complementary loss and gain of function experiments and RNA sequencing demonstrate that miR-424(322)/503 regulates a conserved genetic program involved in the differentiation and commitment of white adipocytes. Mechanistically, it is demonstrated that miR-424(322)/503 targets γ-Synuclein (SNCG), a factor that mediates this program rearrangement by controlling metabolic functions in fat cells, allowing adipocyte differentiation and adipose tissue enlargement. Accordingly, diminished miR-424(322) in mice and obese humans co-segregate with increased SNCG in fat and peripheral blood as mutually exclusive features of obesity, being normalized upon weight loss. The data unveil a previously unknown regulatory mechanism of fat mass expansion tightly controlled by the miR-424(322)/503 through SNCG.

MiRNA-424-5p Suppresses Proliferation, Migration, and Invasion of Clear Cell Renal Cell Carcinoma and Attenuates Expression of O-GlcNAc-Transferase

Simple Summary

The identification of biomarkers that predict the metastatic potential of tumors is a current area of interest in cancer research. A previous study from our laboratory identified numerous microRNA (miRNA) biomarkers that are differentially expressed in pathologic stage I clear cell renal cell carcinoma (ccRCC) tumors that progress to metastatic disease. This study investigated the role of aberrant expression of one of these miRNA, miR-424-5p, and one of its associated protein targets, O-GlcNAc-transferase (OGT). We examined the influence of miR-424-5p and OGT expression on the proliferation, migration, and invasion of ccRCC cells, and confirmed the direct interaction between miR-424-5p and OGT. These findings suggest that the decrease in miR-424-5p expression observed in these small renal masses leads to an increase in OGT, which facilitates metastasis.

Abstract

MicroRNAs (miRNAs) are non-coding post-transcriptional regulators of gene expression that are dysregulated in clear cell renal cell carcinoma (ccRCC) and play an important role in tumor progression. Our prior work identified a subset of miRNAs in pT1 ccRCC tumors, including miR-424-5p, that are associated with an aggressive phenotype. We investigate the impact of this dysregulated miRNA and its protein target O-GlcNAc-transferase (OGT) to better understand the mechanisms behind aggressive stage I ccRCC. The ccRCC cell lines 786-O and Caki-1 were used to assess the impact of miR-424-5p and OGT. Cells were transfected with pre-miR-424-5p, a lentiviral anti-OGT shRNA, or were treated with the demethylating agent 5-Aza-2′-deoxycytidine. Cell proliferation was measured via MT cell viability assay. Cell migration and invasion were analyzed using Transwell assays. The expression of miR-424-5p was determined through qRT-PCR, while OGT protein expression was evaluated through Western blotting. The interaction between miR-424-5p and OGT was confirmed via luciferase reporter assay. The transfection of ccRCC cells with pre-miR-424-5p or anti-OGT shRNA significantly inhibited cell proliferation, migration, and OGT expression, while miR-424-5p also attenuated cell invasion. Addition of the demethylating agent significantly reduced cell proliferation, migration, invasion, and OGT expression, while significantly increasing the expression of miR-424-5p. Altogether, these findings suggest that epigenetic downregulation of miR-424-5p, which in turn augments OGT expression, contributes to the creation of aggressive forms of stage I ccRCC.

Interplay between DNA Methyltransferase 1 and microRNAs During Tumorigenesis

Cancer is a genetic disease resulting from genomic changes; however, epigenetic alterations act synergistically with these changes during tumorigenesis and cancer progression. Epigenetic variations are gaining more attention as an important regulator in tumor progression, metastasis and therapy resistance. Aberrant DNA methylation at CpG islands is a central event in epigeneticmediated gene silencing of various tumor suppressor genes. DNA methyltransferase 1 (DNMT1) predominately methylates at CpG islands on hemimethylated DNA substrates in proliferation of cells. DNMT1 has been shown to be overexpressed in various cancer types and exhibits tumor-promoting potential. The major drawbacks to DNMT1-targeted cancer therapy are the adverse effects arising from nucleoside and non-nucleoside based DNMT1 inhibitors. This paper focuses on the regulation of DNMT1 by various microRNAs (miRNAs), which may be assigned as future DNMT1 modulators, and highlights how DNMT1 regulates various miRNAs involved in tumor suppression. Importantly, the role of reciprocal inhibition between DNMT1 and certain miRNAs in tumorigenic potential is approached in this review. Hence, this review seeks to project an efficient and strategic approach using certain miRNAs in conjunction with conventional DNMT1 inhibitors as a novel cancer therapy. It has also been pinpointed to select miRNA candidates associated with DNMT1 regulation that may not only serve as potential biomarkers for cancer diagnosis and prognosis, but may also predict the existence of aberrant methylation activity in cancer cells.

miR-424 induces apoptosis in glioblastoma cells and targets AKT1 and RAF1 oncogenes from the ERBB signaling pathway

Glioblastoma is a lethal and incurable cancer. Tumor suppressor miRNAs are promising gene therapy tools for cancer treatment. In silico, we predicted miR-424 as a tumor suppressor. It had several target genes from the epidermal growth factor receptor (ERBB) signaling pathway that are overactive in most glioblastoma cases. We overexpressed miR-424 by lentiviral transduction of U-251 and U-87 glioblastoma cells confirmed with fluorescent microscopy and real-time quantitative PCR (qRT-PCR). Then the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) proliferation assay and scratch wound migration assay were performed to investigate the miR-424 tumor suppressor effect in glioblastoma. miR-424's effect on glioblastoma apoptosis and cell-cycle arrest was verified using Annexin V- phosphatidylethanolamine (PE) and 7-minoactinomycin D (7-AAD) apoptosis assay and cell-cycle assay. miR-424 predicted target genes mRNA and protein level were measured after miR-424 overexpression in comparison to the control group by qRT-PCR and western blotting, respectively. We confirmed miR-424 direct target genes by dual-luciferase reporter assay. miR-424 overexpression significantly suppressed cell proliferation and migration rate in glioblastoma cells based on the MTT and scratch assays. Flow cytometry results confirmed that miR-424 promotes apoptosis and cell-cycle arrest in glioblastoma cells. Predicted target genes of miR-424 from the ERBB pathway were downregulated by miR-424 overexpression. qRT-PCR and western blotting showed that KRAS, RAF1, MAP2K1, EGFR, PDGFRA, AKT1, and mTOR mRNA expression levels and KRAS, RAF1, MAP2K1, EGFR, and AKT1 protein level, respectively, had significantly decreased as a result of miR-424 overexpression in comparison to the control group. Dual-luciferase reporter assay confirmed that miR-424 directly targets RAF1 and AKT1 oncogenes. Overall, miR-424 acts as tumor suppressor miRNA in glioblastoma cells.

The miR-424(322)/503 gene cluster regulates pro- versus anti-inflammatory skin DC subset differentiation by modulating TGF-β signaling

Transforming growth factor β (TGF-β) family ligands are key regulators of dendritic cell (DC) differentiation and activation. Epidermal Langerhans cells (LCs) require TGF-β family signaling for their differentiation, and canonical TGF-β1 signaling secures a non-activated LC state. LCs reportedly control skin inflammation and are replenished from peripheral blood monocytes, which also give rise to pro-inflammatory monocyte-derived DCs (moDCs). By studying mechanisms in inflammation, we previously screened LCs versus moDCs for differentially expressed microRNAs (miRNAs). This revealed that miR-424/503 is the most strongly inversely regulated (moDCs > LCs). We here demonstrate that miR-424/503 is induced during moDC differentiation and promotes moDC differentiation in human and mouse. Inversely, forced repression of miR-424 during moDC differentiation facilitates TGF-β1-dependent LC differentiation. Mechanistically, miR-424/503 deficiency in monocyte/DC precursors leads to the induction of TGF-β1 response genes critical for LC differentiation. Therefore, the miR-424/503 gene cluster plays a decisive role in anti-inflammatory LC versus pro-inflammatory moDC differentiation from monocytes.

Epigenetic Regulation of MicroRNA Clusters and Families during Tumor Development

MicroRNAs are small non-coding single-stranded RNA molecules regulating gene expression on a post-transcriptional level based on the seed sequence similarity. They are frequently clustered; thus, they are either simultaneously transcribed into a single polycistronic transcript or they may be transcribed independently. Importantly, microRNA families that contain the same seed region and thus target related signaling proteins, may be localized in one or more clusters, which are in a close relationship. MicroRNAs are involved in basic physiological processes, and their deregulation is associated with the origin of various pathologies, including solid tumors or hematologic malignancies. Recently, the interplay between the expression of microRNA clusters and families and epigenetic machinery was described, indicating aberrant DNA methylation or histone modifications as major mechanisms responsible for microRNA deregulation during cancerogenesis. In this review, the most studied microRNA clusters and families affected by hyper- or hypomethylation as well as by histone modifications are presented with the focus on particular mechanisms. Finally, the diagnostic and prognostic potential of microRNA clusters and families is discussed together with technologies currently used for epigenetic-based cancer therapies.

LINC01116 Promotes Doxorubicin Resistance in Osteosarcoma by Epigenetically Silencing miR-424-5p and Inducing Epithelial-Mesenchymal Transition

Background: Development of resistance to doxorubicin-based chemotherapy limits its curative effect in osteosarcoma. In the current study, we focused on investigating the mechanisms underlying the development of doxorubicin resistance in osteosarcoma.

Methods: The human osteosarcoma cell line MG-63 and doxorubicin-resistant MG-63/Dox cells were used in this study. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of the long non-coding RNA LINC01116 in the two cell lines. Then, the specific shRNA for LINC01116 was employed to suppress LINC01116 expression in MG-63/Dox cells. Cell viability was assessed by the CCK-8 and colony formation assays. Cell migration and invasion were evaluated by the transwell assay. Moreover, the epithelial-mesenchymal transition (EMT)-related proteins, E-cadherin, vimentin, and N-cadherin were evaluated by Western blotting. The regulation of LINC01116 on miR-424-5p expression was examined using methylation-specific PCR, RNA immunoprecipitation, and Western blotting assay. The potential targeting of HMGA2 by miR-424-5p was predicted using the bioinformatics databases TargetScan and miRanda and verified by a dual-luciferase reporter assay.

Results: LINC01116 was more highly expressed in MG-63/Dox cells than in MG-63 cells. Inhibition of LINC01116 suppressed cell viability, migration, and invasion, along with upregulating the expression of E-cadherin, downregulating vimentin, and attenuating doxorubicin resistance in MG-63/Dox cells. Further mechanism-related investigations indicated that LINC01116 regulated HMGA2 expression via the EZH2-associated silencing of miR-424-5p.

Conclusion: LINC01116 exerts regulatory effects on doxorubicin resistance through the miR-424-5p axis, providing a potential approach to overcoming chemoresistance in osteosarcoma.

Hypermethylated miR-424 in Colorectal Cancer Subsequently Upregulates VEGF

PURPOSE

Colorectal cancer (CRC) is the second leading cause of death from cancer in adults. Recent advances have shown that cancer cells can have some epigenetic changes involved in all stages of cancer. It has also been shown that miR-424 acts as gene expression regulators in many biological processes, including angiogenesis with mediators such as VEGF. In the current study, to identify the potential role of miR-424 in colorectal cancer progression, methylation status of miR-424 promoter region and its expression level have been evaluated. Besides, the correlation between VEGF level and miR-424 expression level has been assessed.

METHODS

Methylation status miR-424 promoter was assessed using methylation-specific polymerase chain reaction (MSP). The expression level of miR-424 in human colorectal cancer tissue was analyzed by quantitative PCR. HCT116 cell line was selected to evaluate the correlation between the miR-424 expression level and the promoter's methylation status. VEGF expression, one out of mir-424 targets involved in angiogenesis and cancer progression, was measured by western blot analysis in the pairs of cancer tissues and their adjacent tissues.

RESULTS

Our results have revealed that the promoter region of miR-424 is methylated in cancer cells compared to normal cells, leading to downregulation of miR-424 in the colorectal cancer tissues compared to the normal tissues. Also, we found that the expression protein's level of VEGF in the tumor cells is increased compared with normal tissues.

CONCLUSION

The present study suggests that hypermethylation downregulates miR-424. VEGF expression is upregulated with decreased miR-424 in colorectal cancer, which results in cancer progression.

The essential role of long non-coding RNA GAS5 in glioma: interaction with microRNAs, chemosensitivity and potential as a biomarker

Glioma is a malignant brain tumor with a generally poor prognosis. Dysregulation of a long non-coding RNA, GAS5, has been detected in numerous cancers, including glioma. Previous studies have suggested that GAS5 plays a significant functional role in glioma, affecting proliferation, metastasis, invasion, and apoptosis. In this review, we describe the roles and mechanisms of GAS5 in glioma. GAS5 may be a biomarker for diagnosis and prognosis, and even a potential target for glioma treatment, and therefore warrants further investigation.

Ropivacaine inhibits proliferation, migration, and invasion while inducing apoptosis of glioma cells by regulating the SNHG16/miR-424-5p axis

BACKGROUND

Regional anesthesia has anti-proliferative and pro-apoptotic effects in various cancers. Therefore, the purpose of this study was to investigate the effects of ropivacaine on the proliferation, migration, invasion, and apoptosis of glioma cells in vitro.

METHODS

Under ropivacaine stimulation conditions, proliferation, apoptosis, migration, and invasion of glioma cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazol-3-ium bromide (MTT), flow cytometry, and transwell assays, respectively. Western blot assay was employed to measure the protein expression levels in glioma cells. The expression levels of small nucleolar RNA host gene 16 (SNHG16) and miR-424-5p were assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The interaction relationship between SNHG16 and miR-424-5p was predicted and confirmed using a bioinformatics database and dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays.

RESULTS

After treatment with ropivacaine, proliferation, migration, and invasion were repressed while apoptosis was enhanced in glioma cells in a dose-depended manner. In addition, ropivacaine impeded SNHG16 expression in glioma cells. Importantly, overexpression of SNHG16 abolished the ropivacaine-induced effects on glioma cells. Analogously, knockdown of miR-424-5p counteracted the function of ropivacaine in glioma cells. We also found that SNHG16 bound to miR-424-5p and negatively regulated miR-424-5p expression in glioma cells. The rescue experiments indicated that ropivacaine might regulate glioma progression by targeting the SNHG16/miR-424-5p axis.

CONCLUSION

Our findings revealed the anti-tumor effects of ropivacaine in glioma by targeting the SNHG16/miR-424-5p axis. These data might extend the understanding of regulatory mechanisms by which ropivacaine could suppress glioma development.

miR-424: A novel potential therapeutic target and prognostic factor in malignancies

microRNAs are endogenous, noncoding RNAs. Showing both tumor-suppressive and oncogenic characteristics, miRNAs can regulate important processes in malignancies. This review aimed at highlighting the recent studies on the contribution of miR-424 to the modulation of carcinogenesis and exploring its probable clinical effectiveness in the diagnosis and therapy of malignancies. The data were extracted from all papers published from 2013 until 2020. Mature miR-424 leads to the degradation of its target transcripts or the suppression of translation via binding to the molecular targets. miR-424 is involved in modulating p53, PI3K/Akt, Wnt, and other molecular pathways, thereby regulating cellular growth, apoptosis, differentiation, chemoresistance, and cancer immunity. miR-424 was introduced as a tumor-suppressive miR in numerous types of cancers while as an oncogene in several cancers. Regarding the cancer dependent role of miR-424, it may be a prognostic and diagnostic biomarker and a potential candidate for the treatment of cancers.

Epigenetics of glioblastoma multiforme: From molecular mechanisms to therapeutic approaches

Glioblastoma multiforme (GBM) is the most common form of brain cancer and one of the most aggressive cancers found in humans. Most of the signs and symptoms of GBM can be mild and slowly aggravated, although other symptoms might demonstrate it as an acute ailment. However, the precise mechanisms of the development of GBM remain unknown. Due to the improvement of molecular pathology, current researches have reported that glioma progression is strongly connected with different types of epigenetic phenomena, such as histone modifications, DNA methylation, chromatin remodeling, and aberrant microRNA. Furthermore, the genes and the proteins that control these alterations have become novel targets for treating glioma because of the reversibility of epigenetic modifications. In some cases, gene mutations including P16, TP53, and EGFR, have been observed in GBM. In contrast, monosomies, including removals of chromosome 10, particularly q23 and q25-26, are considered the standard markers for determining the development and aggressiveness of GBM. Recently, amid the epigenetic therapies, histone deacetylase inhibitors (HDACIs) and DNA methyltransferase inhibitors have been used for treating tumors, either single or combined. Specifically, HDACIs are served as a good choice and deliver a novel pathway to treat GBM. In this review, we focus on the epigenetics of GBM and the consequence of its mutations. We also highlight various treatment approaches, namely gene editing, epigenetic drugs, and microRNAs to combat GBM.

The microRNA-424/503 cluster: A master regulator of tumorigenesis and tumor progression with paradoxical roles in cancer

MicroRNAs (miRNAs) are a group of non-coding RNAs that play a crucial role in post-transcriptional gene regulation and act as indispensable mediators in several critical biological processes, including tumorigenesis, tissue homeostasis, and regeneration. MiR-424 and miR-503 are intragenic miRNAs that are clustered on human chromosome Xq26.3. Previous studies have reported that both miRNAs are dysregulated and play crucial but paradoxical roles in tumor initiation and progression, involving different target genes and molecular pathways. Moreover, these two miRNAs are concomitantly expressed in several cancer cells, indicating a coordinating function as a cluster. In this review, the roles and regulatory mechanisms of miR-424, miR-503, and miR-424/503 cluster are summarized in different types of cancers.

miR-525-5p Modulates Proliferation and Epithelial-Mesenchymal Transition of Glioma by Targeting Stat-1

Background

Glioma is the most aggressive human brain tumor. Recent studies revealed that microRNAs play vital roles in glioma. However, the function of microRNA-525-5p (miR-525-5p) in glioma remains unclear.

Methods

qRT-PCR and Western blotting were used to evaluate mRNA and protein levels in glioma tissues and cells. Colony formation, CCK-8, and Edu assays evaluated the growth of glioma cells. Wound-healing, transwell, and 3D invasion assays examined the migration and invasion activities of glioma cells. Luciferase reporter assays assessed the regulatory relationship interaction between miR-525-5p and Stat-1. A mouse xenograft model was used to examine the effect of miR-525-5p on glioma in vivo.

Results

miR-525-5p expression was downregulated in glioma tissues and cells. Overexpressing miR-525-5p decreased the growth of glioma cells and reduced the migration, invasion, and epithelial–mesenchymal transition of glioma cells. Bioinformatics analysis identified Stat-1 as a potential target of miR-525-5p, and dual luciferase reporter assays revealed that miR-525-5p negatively regulates Stat-1. Decreased Stat-1 led to the inhibition of FOXM1, affecting NF-κB signaling activity. Overexpressing miR-525-5p reduced tumor development in vivo.

Conclusion

miR-525-5p negatively regulates cell proliferation, migration, invasion, and epithelial–mesenchymal transition in glioma, and Stat 1 is a target of miR-525-5p. miR-525-5p may be a potential target for glioma treatment.

LINC00657 knockdown suppresses hepatocellular carcinoma progression by sponging miR-424 to regulate PD-L1 expression

BACKGROUND

Hepatocellular carcinoma (HCC) is the sixth most commonly diagnosed malignant tumor and the fourth leading cause of cancer-related deaths worldwide. As a novel non-coding RNA, LINC00657 was firstly identified as an oncogenic role in breast cancer. However, few research focus on the effect of LINC00657 on the progression of HCC.

OBJECTIVES

The purpose of this study was to investigate the effect of LINC00657 on HCC tissues and cells, and further explore the potential mechanism.

METHODS

We first measured the expression of LINC00657 in HCC tissues and cell lines using qRT-PCR. Next we established LINC00657 knockdown in HCC cells. CCK-8 assay, cell invasion assay, flow cytometry analysis, qRT-PCR and western blotting were applied to assess the role of LINC00657 knockdown in the biological behavior of HCC cells. The bioinformatics analysis and the rescue experiment were devoted to the underlying mechanism.

RESULTS

LINC00657 was remarkably overexpressed in HCC tissues and cell lines, associated with poor prognosis. LINC00657 knockdown repressed cell proliferation and invasion, promoted cell apoptosis of HCC cell lines. The bioinformatics analysis showed LINC00657 sponged miR-424 as a ceRNA. Besides, PD-L1 mimic rescued the suppression of si-LINC00657 in the biological behavior of HCC cells.

CONCLUSION

In a word, we observed LINC00657 regulated PD-L1 expression by sponging miR-424, thus affecting the developments of hepatocellular carcinoma. These findings LINC00657 may provide new evidence for therapeutic application in hepatocellular carcinoma.

Role of miRNA-424 in Cancers

microRNA (miRNA) is an important part of non-coding RNA that regulates gene expression at a posttranscriptional level. miRNA has gained increasing interest in recent years, both in research and clinical fields. miRNAs have been found to play an important role in various diseases, particularly cancer. Aberrant miR-424 expression is found in several tumors where they can function as either oncogenes or tumor-suppressor genes. Meanwhile, miR-424 is also affected by the reorganization of many other non-coding RNAs such as lncRNA and cirRNA. Several studies have found that miR-424 participates in proliferation, differentiation, apoptosis, invasion, angiogenesis, and drug resistance, and plays an important role in the tumorigenesis and progression of tumors. This review will focus on the recent progress of research on miR-424 in tumors.

Long non-coding RNA GAS5, by up-regulating PRC2 and targeting the promoter methylation of miR-424, suppresses multiple malignant phenotypes of glioma

PURPOSE

Malignant gliomas remain significant challenges in clinic and pose dismal prognosis on patients. In this study, we focused on growth arrest-specific 5 (GAS5), a tumor suppressive long non-coding RNA in glioma, explored its crosstalk with miR-424, and examined their biological functions in glioma.

METHODS

Expressions of GAS5 and miR-424 were measured using qRT-PCR. The regulation of GAS5 on miR-424 expression was examined in GAS5-overexpressing glioma cells by combining methylation-specific PCR, western blotting, and RNA immunoprecipitation. Functional significance of GAS5 and miR-424 on in vitro cell proliferation, apoptosis, migration, invasion, and in vivo tumor growth was examined using colony formation, flow cytometry, wound healing, transwell assay, and the xenograft model, respectively. The potential targeting of AKT3 by miR-424 was investigated using luciferase reporter assay.

RESULTS

GAS5 and miR-424 were significantly down-regulated in glioma cells. GAS5 directly interacted with enhancer of zeste homolog 2 (EZH2), stimulated the formation of polycomb repressive complex 2 (PRC2), reduced the levels of DNA methyltransferases (Dnmts), alleviated promoter methylation of miR-424, and promoted miR-424 expression. Functionally, GAS5, by up-regulating miR-424, inhibited cell proliferation, migration, and invasion, while increased apoptosis of glioma cells in vitro, and suppressed xenograft growth in vivo. miR-424 directly inhibited AKT3 and altered the expressions of AKT3 targets, cyclinD1, c-Myc, Bax, and Bcl-2, which might contribute to its tumor suppressive activities.

CONCLUSIONS

GAS5, by inhibiting methylation and boosting expression of miR-424, inhibits AKT3 signaling and suppresses multiple malignant phenotypes. Therefore, stimulating GAS5/miR-424 signaling may benefit the treatment of glioma.

LncRNA CCAT2 promotes angiogenesis in glioma through activation of VEGFA signalling by sponging miR-424

Glioma is characterized by high morbidity, high mortality and poor prognosis. Recent studies exhibited that lncRNA CCAT2 is overexpressed in glioma and promotes glioma progression, but the specific molecular biological mechanism remains to be determined. We performed qRT-PCR to evaluate the expression of related genes, Western blotting analysis to measure protein levels, colony formation assay to detect the proliferative ability of glioma cells, flow cytometry to measure cell apoptosis, bioinformatics analysis and dual luciferase assay to verify the binding sites and the targeted regulatory relationship in A172 and U251 cell lines and tube formation assay to determine endothelial angiogenesis. LncRNA CCAT2 and VEGFA were highly expressed, while miR-424 was expressed at low levels in NHA cells. Furthermore, knockdown of lncRNA CCAT2 decreased cell proliferation, increased cell apoptosis and inhibited endothelial angiogenesis in glioma. Moreover, lncRNA CCAT2 shared a complementary sequence with miR-424 which in turn directly bound to the 3'-UTR of VEGFA. Further investigation indicated that lncRNA CCAT2 promoted cell proliferation and endothelial angiogenesis by inducing the PI3K/AKT signalling pathway in glioma. The oncogenic lncRNA CCAT2 is highly associated with the development of glioma and exerts its function by upregulating VEGFA via miR-424.

MiRNAs in endometrioid endometrial cancer metastatic loci derived from positive lymph nodes

INTRODUCTION

MicroRNAs (miRNAs) take part in tumorigenesis and show aberrant expression levels in cancerous tissues. We aimed to perform miRNA profiling of endometrioid endometrial cancer (EEC) metastatic loci derived from lymph nodes. Identification of aberrant miRNAs in positive lymph nodes could contribute to establishing new diagnostic markers and therapeutic targets.

MATERIAL AND METHODS

During the screening phase of the study, we performed profiling of 754 human miRNAs in endometrioid endometrial cancer tissues, microdissected metastatic loci from lymph nodes and healthy lymph nodes (Taqman Array). Selection of candidate miRNAs and subsequent validation using quantitative reverse transcription polymerase chain reaction (qRT-PCR) in 50 tissue samples were performed.

RESULTS

After the screening phase of the study, five miRNAs were selected (hsa-miR-18b, hsa-miR-148a-5p, hsa-miR-204, hsa-miR-424, hsa-miR-129-1-3p). Validation revealed that miRNA-204 and miRNA-424 were highly downregulated in metastatic tissues compared with endometrial cancer samples (hsa-miR-204-P = .0008; hsa-miR-424-P = .0001). Receiver operating characteristic curves, which were constructed to compare endometrioid endometrial cancer and positive endometrioid endometrial cancer lymph nodes yielded the following area under the curves (AUCs): hsa-miR-204-.802 (96% confidence interval CI 0.676-0.927), hsa-miR-424-.84 (95% CI 0.711-0.969).

CONCLUSIONS

Compared with primary endometrioid endometrial cancer tissue, metastatic loci derived from positive lymph nodes are characterized by profound downregulation of miRNA-204 and miRNA-424.

lncRNA CCAT2 Enhanced Resistance of Glioma Cells Against Chemodrugs by Disturbing the Normal Function of miR-424

Background

Aggressive metastasis of tumor cells assumed a constructive role in strengthening chemoresistance of tumors, so this investigation was intended to elucidate if lncRNA CCAT2 sponging downstream miR-424 regulated chemotolerance of glioma cells by boosting metastasis of glioma cells.

Methods

One hundred and twenty-eight pairs of glioma tissues and corresponding adjacent tissues were resected from glioma patients during their operation, and we also purchased a series of glioma cell lines, including U251, U87, A172 and SHG44. Furthermore, pcDNA3.1-CCAT2, si-CCAT2, miR-424 mimic and miR-424 inhibitor were transfected into SHG44 and U251 cell lines, so as to evaluate impacts of CCAT2 and miR-424 on chemosensitivity of the glioma cells. Besides, proliferation, invasion and metastasis of the cells were determined through the implementation of colony formation assay, transwell assay and scratch assay.

Results

Glioma tissues and cells were monitored with higher CCAT2 expression and lower miR-424 expression than adjacent normal tissues and NHA cell line (P<0.05). Among the glioma cell lines, the SHG44 cell line showed the strongest resistance against teniposide, temozolomide and cisplatin (P<0.05), whereas the U251 cell line was more sensitive to teniposide, temozolomide, vincristine and cisplatin than any other cell line (P<0.05). Besides, pcDNA3.1-CCAT2 and miR-424 inhibitor could enhance tolerance of glioma cell lines against drugs (P<0.05). Moreover, in-vitro transfection of si-CCAT2 and miR-424 mimic could significantly retard proliferation, invasion and migration of SHG44 and U251 cells (P<0.05), and CCAT2 was found to negatively regulate miR-424 expression by sponging it (P<0.05). In addition, CHK1 was deemed as the molecule targeted by upstream miR-424, and its overexpression can changeover the effects of miR-424 mimic on proliferation and metastasis of SHG44 and U251 cells.

Conclusion

lncRNA CCAT2/miR-424/Chk1 axis might serve as a promising target for improving chemotherapeutic efficacies in glioma treatment.

Osthole inhibited cell proliferation and induced cell apoptosis through decreasing CPEB2 expression via up-regulating miR-424 in endometrial carcinoma

Objective: Endometrial carcinoma (EC) was the fourth female malignancies in developed countries. Given that the prognosis of EC is extremely poor, it is vital to investigate its pathogenesis and effective therapeutic targets. However, the mechanism of osthole in EC remains unknown.Materials and methods: Firstly, the different doses of osthole (0, 50, 100, and 200 μM) were used to treat the Ishikawa and KLE cells. The cell proliferation, apoptosis, and cell cycle were measured by cell counting kit-8 (CCK-8), Annexin V-FITC/PI, and cell cycle assays. The apoptosis-related protein levels were examined by western blot. The miR-424 levels in Ishikawa and KLE cells were assessed by quantitative RT-PCR (qRT-PCR). Also, the binding of miR-424 and cytoplasmic polyadenylation element binding protein 2 (CEPB2) was detected by the luciferase reporter assay.Results: In this study, the increasing dose of osthole inhibited proliferation and induced apoptosis of Ishikawa and KLE cells. Moreover, the increasing dose of osthole up-regulated miR-424 and down-regulated the expression of CPEB2. CPEB2 was proved to be the target gene of miR-424. Interestingly, the over-expression of CPEB2 could reverse the changes of osthole-induced proliferation and apoptosis of Ishikawa and KLE cells.Conclusions: In summary, we provided first evidences that osthole inhibited proliferation and induced apoptosis through up-regulating miR-424 to inhibit expression of CPEB2 in EC. Our findings indicated that osthole might act as a novel and potential therapeutic agent for the treatment of EC.

miR-424-5p Promotes Proliferation, Migration and Invasion of Laryngeal Squamous Cell Carcinoma

Background

Recent studies revealed that miR-424-5p regulates the malignant behavior of multiple cancer types. However, the expression and function of miR-424-5p in laryngeal squamous cell carcinoma (LSCC) is unclear.

Purpose

This study aimed to evaluate the association of miR-424-5p level with clinical features of LSCC and investigate the effect and potential mechanism of miR-424-5p on LSCC progression.

Methods

The expression of miR-424-5p in LSCC and paired adjacent normal margin (ANM) tissues from 106 patients with LSCC were analyzed by quantitative PCR (qPCR), and clinical significance was analyzed. Target genes of miR-424-5p were predicted, followed by functional annotation. The functional role of miR-424-5p in LSCC was investigated by molecular and cellular experiments with LSCC cell lines, with flow cytometry used for cell cycle analysis. In addition, miR-424-5p regulation of the predicted target gene cell adhesion molecule 1 (CADM1) was validated by qPCR, Western blot analysis and luciferase reporter assay.

Results

miR-424-5p was upregulated in LSCC versus ANM tissues. High miR-424-5p level was significantly associated with poor differentiation, advanced tumor stage and cervical lymph node metastasis. Bioinformatics analysis showed that miR-424-5p target genes are mainly enriched in biological processes of the cell cycle, cell division, and negative regulation of cell migration, and were involved in multiple cancer-related pathways. Overexpression of miR-424-5p promoted proliferation, migration, invasion, and adhesion of LSCC cells and affected the cell cycle progression. Additionally, CADM1 was a direct target of miR-424-5p in LSCC cells.

Conclusion

miR-424-5p functions as an oncogene to promote the aggressive progression of LSCC, and CADM1 is a direct downstream target of miR-424-5p in LSCC cells. miR-424-5p may be a potential therapeutic target in LSCC.

MicroRNA-6852 suppresses glioma A172 cell proliferation and invasion by targeting LEF1

microRNA (miR)-6852 has been demonstrated to suppress the progression of gastric, colorectal and cervical cancer. The mechanism by which miR-6852 regulates glioma cells is yet to be elucidated. In the present study, reverse transcription-quantitative PCR analysis was used and the results demonstrated that miR-6852 expression was reduced in glioma tissues and cells. Cell counting kit-8 and transwell assay analysis indicated that proliferation, migration and invasion of A172 cells in the miR-6852 mimic group were lower than in the miR-NC group. Compared with the Inh-NC group, A172 cells of the Inh-miR-6852 group exhibited higher proliferation, migration and invasion. Additionally, the results indicated that lymphoid enhancer binding factor 1 (LEF1) was directly inhibited by miR-6852 and LEF1 expression was negatively correlated with miR-6852 expression in glioma tissues. Furthermore, the restoration of LEF1 reversed the effects of the miR-6852 mimics. The present findings suggested that miR-6852 inhibited glioma cells proliferation, migration and invasion by targeting the suppression of LEF1.

Methylation-mediated repression of MiR-424/503 cluster promotes proliferation and migration of ovarian cancer cells through targeting the hub gene KIF23

Ovarian cancer is one type of gynecological malignancies with extremely high lethal rate. Abnormal proliferation and metastasis are regarded to play important roles in patients' death, whereas we know little about the underlying molecular mechanisms. Under this circumstance, our current study aims to investigate the role of hub genes in ovarian cancer. Bioinformatics analysis of the data from GEO and analyses of ovarian cancer samples were performed. Then, the results showed that KIF23, a hub gene, was mainly related to cell cycle and positively associated with poor prognosis. Meanwhile, both miR-424-5p and miR-503-5p directly targeted to 3'UTR of KIF23 to suppress the expression of KIF23 and inhibit ovarian cancer cell proliferation and migration. Furthermore, we discovered that miR-424/503 was epigenetically repressed by hypermethylation in the promoter regions, which directly modulated the expression of KIF23 to improve the oncogenic performance of cancer cells in vitro. Together, our research certifies that miR-424/503 cluster is silenced by DNA hypermethylation, which promotes the expression of KIF23, thereby regulating the proliferation and migration of ovarian cancer cells. Interposing this process might be a novel approach in cancer therapy.

MiR-205 suppresses epithelial-mesenchymal transition and inhibits tumor growth of human glioma through down-regulation of HOXD9

Epithelial-mesenchymal transition (EMT) plays a pivotal role in cancer progression. Hsa-miR-205 is considered one of the fundamental regulators of EMT. In the present study, we found that miR-205 was down-regulated in glioma tissues and human glioma cells U87 and U251. Meanwhile, miR-205 overexpression enhanced E-cadherin, reduced mesenchymal markers, and decreased cell proliferation, migration, and invasion in vitro. In vivo, miR-205 suppressed tumor growth. Additionally, HOXD9 was confirmed as a direct target of miR-205. Suppression of HOXD9 by miR-205 was demonstrated by luciferase reporter assay, quantitative real time-PCR analysis, and western blot. Moreover, we observed a negative correlation between miR-205 and HOXD9 in human glioma tissues. In summary, our findings demonstrated that miR-205 suppresses glioma tumor growth, invasion, and reverses EMT through down-regulating its target HOXD9.

miR-125b Upregulates miR-34a and Sequentially Activates Stress Adaption and Cell Death Mechanisms in Multiple Myeloma

miR-125b, ubiquitously expressed and frequently dysregulated in several tumors, has gained special interest in the field of cancer research, displaying either oncogenic or oncosuppressor potential based on tumor type. We have previously demonstrated its tumor-suppressive role in multiple myeloma (MM), but the analysis of molecular mechanisms needs additional investigation. The purpose of this study was to explore the effects of miR-125b and its chemically modified analogs in modulating cell viability and cancer-associated molecular pathways, also focusing on the functional aspects of stress adaptation (autophagy and senescence), as well as programmed cell death (apoptosis). Based on the well-known low microRNA (miRNA) stability in therapeutic application, we designed chemically modified miR-125b mimics, laying the bases for their subsequent investigation in in vivo models. Our study clearly confirmed an oncosuppressive function depending on the repression of multiple targets, and it allowed the identification, for the first time, of miR-125b-dependent miR-34a stimulation as a possible consequence of the inhibitory role on the interleukin-6 receptor (IL-6R)/signal transducer and activator of transcription 3 (STAT3)/miR-34a feedback loop. Moreover, we identified a pattern of miR-125b-co-regulated miRNAs, shedding light on possible new players of anti-MM activity. Finally, functional studies also revealed a sequential activation of senescence, autophagy, and apoptosis, thus indicating, for the first two processes, an early cytoprotective and inhibitory role from apoptosis activation.

Knockdown of lncRNA PVT1 Inhibits Glioma Progression by Regulating miR-424 Expression

Plasmacytoma variability translocation 1 (PVT1), an oncogene, has been reported to be highly expressed in many tumors, including human glioma, gastric cancer, and non-small cell lung cancer. Functionally, it could also regulate the development of tumor cells. However, its specific roles and pathogenesis in human gliomas are still not clear. This study investigated the function and mechanism of PVT1 knockdown in the proliferation and malignant transformation of human gliomas. We first examined the expression levels of PVT1 and miR-424 in human glioma tissues and cell lines. We also used gene manipulation techniques to explore the effects of PVT1 knockdown on cell viability, migration, invasion, and miR-424. We found that PVT1 knockdown effectively inhibited cell viability, migration, and invasion of human glioma cells and increased miR-424 expression. Based on the negative correlation between PVT1 and miR-424, we then confirmed the direct interaction between PVT1 and miR-424 using RNA immunoprecipitation (RIP) and luciferase reporter assays. Further, we established a xenograft nude mouse model to determine the role and mechanism of PVT1 on tumor growth in vivo. In addition, PVT1 knockdown was shown to promote miR-424 in vivo. In summary, the present study demonstrated that PVT1 knockdown could negatively regulate miR-424 to inhibit human glioma cell activity, migration, and invasiveness. PVT1 knockdown could negatively regulate miR-424 to inhibit cellular activity, migration, and invasiveness in human gliomas, which explained the oncogenic mechanism of PVT1 in human gliomas. It also suggested that PVT1 might be a novel therapeutic target for human gliomas.

The roles of microRNAs in epigenetic regulation

MicroRNAs (miRNAs) are small noncoding RNAs, approximately 18-25 nucleotides in length, now recognized as one of the major regulatory gene families in eukaryotes. Recent advances have been made in understanding the complicated roles of miRNAs in epigenetic regulation. miRNAs, as epigenetic modulators, affect the protein levels of the target mRNAs without modifying the gene sequences. Moreover, miRNAs can also be regulated by epigenetic modifications, including DNA methylation, RNA modification, and histone modifications. The reciprocal actions of miRNAs and epigenetic pathway appear to form a miRNA-epigenetic feedback loop and have an extensive influence on gene expression proliferation. The dysregulation of the miRNA-epigenetic feedback loop interferes with the physiological and pathological processes and contributes to variety of diseases. In this review, we focus on the reciprocal interconnection of miRNAs in epigenetic regulation, with the aim of offering new insights into the epigenetic regulatory mechanism that can be used to combat diseases.

Long Non-coding RNA PVT1 Competitively Binds MicroRNA-424-5p to Regulate CARM1 in Radiosensitivity of Non-Small-Cell Lung Cancer

Accumulating evidence revealed that dysregulated long non-coding RNAs (lncRNAs) were involved in tumorigenesis and progression. This study is supposed to reveal the effects of lncRNA PVT1 on the radiosensitivity of non-small-cell lung cancer (NSCLC) via the microRNA (miR)-424-5p/lncRNA PVT1/CARM1 signaling pathway. Differentially expressed lncRNA was filtrated. The co-expressed gene of lncRNA was predicted, and gene ontology analysis was performed to find out the genes associated with NSCLC radiosensitivity. The miR that was combined with lncRNA and mRNA was filtrated. Two cell lines with the highest expressed PVT1 were selected, followed by transfection with a series of different mimic, inhibitor, or siRNA. RIP assay was employed for the interaction between PVT1 and CARM1. The regulatory effect of miR-424-5p on cell proliferation, migration, invasion, cycle, and apoptosis was investigated. PVT1 was the most remarkable lncRNA that upregulated in NSCLC. CARM1 co-expressed with lncRNA PVT1 and associated with NSCLC radiosensitivity. Both lncRNA PVT1 and CARM1 can combine with miR-424-5p. Increased PVT1, CARM1, MMP-2, MMP-9, and Bcl-2 and decreased miR-424-5p and Bax were found in NSCLC tissues. PVT1 was targeted by miR-424-5p. After silencing of PVT1 or overexpressed miR-424-5p, decreased PVT1, CARM1, MMP-2, MMP-9, and Bcl-2 inhibited cell proliferation, migration, and invasion but promoted miR-424-5p, Bax, and cell apoptosis. The present study confirms the radiosensitivity of NSCLC radiotherapy can be increased by siRNA-PVT1 and overexpressed miR-424-5p.

Potential Epigenetic-Based Therapeutic Targets for Glioma

Glioma is characterized by a high recurrence rate, short survival times, high rates of mortality and treatment difficulties. Surgery, chemotherapy and radiation (RT) are the standard treatments, but outcomes rarely improve even after treatment. With the advancement of molecular pathology, recent studies have found that the development of glioma is closely related to various epigenetic phenomena, including DNA methylation, abnormal microRNA (miRNA), chromatin remodeling and histone modifications. Owing to the reversibility of epigenetic modifications, the proteins and genes that regulate these changes have become new targets in the treatment of glioma. In this review, we present a summary of the potential therapeutic targets of glioma and related effective treating drugs from the four aspects mentioned above. We further illustrate how epigenetic mechanisms dynamically regulate the pathogenesis and discuss the challenges of glioma treatment. Currently, among the epigenetic treatments, DNA methyltransferase (DNMT) inhibitors and histone deacetylase inhibitors (HDACIs) can be used for the treatment of tumors, either individually or in combination. In the treatment of glioma, only HDACIs remain a good option and they provide new directions for the treatment. Due to the complicated pathogenesis of glioma, epigenetic applications to glioma clinical treatment are still limited.

The miR-503 cluster is coordinately under-expressed in endometrial endometrioid adenocarcinoma and targets many oncogenes, cell cycle genes, DNA repair genes and chemotherapy response genes

Background

The miR-503 miRNA cluster, located at Xq23.1, is composed of six miRNAs; miR-424, miR-503, miR-542, miR-450a-1, miR-450a-2 and miR-450b. Numerous studies have focused on the relationship of one or two members of the cluster and various human cancers. Here, we suggest that the entire cluster as a single coordinately expressed polycistron transcribed from a single promoter in endometrial endometrioid adenocarcinoma (EEA).

Subjects and methods

A tissue panel composed of twenty histologically confirmed endometrial endometrioid adenocarcinomas (EEA) and four benign endometrium was assembled under informed consent. Expression of each member of the miR-503 cluster was determined by quantitative PCR and differences in expression between EEA and benign tissues were assessed via the standard ΔΔCt method. In addition, the role of promoter methylation status in miRNA expression was examined in Ishikawa H cells following exposure to the cytidine analog Decitabine.

Results

Expression of each member of the miR-503 cluster is significantly downregulated in EEA in our tumor sample. Both in our tumor sample and in The Cancer Genome Atlas (TCGA) there is evidence of highly correlated expression further supporting the idea that the miR-503 cluster is a polycistron. Looking at each member of the miR-503 cluster we were able to identify 55 unique experimentally validated target genes which include a substantial number of genes involved in carcinogenesis, DNA damage response, cell cycle regulation and chemotherapeutic response. We also found preliminary evidence that regulation of the miR-503 cluster is governed by methylation of the promoter in EEA.

Conclusion

The totality of the data presented here strongly suggest that the miR-503 cluster as a whole merits further investigation as an important potential therapeutic target in EEA.

MiR-150-3p targets SP1 and suppresses the growth of glioma cells

Glioma has been considered as one of the most prevalent and common malignancy of the nervous system; however, the underlying mechanisms that are responsible for the occurrence and development of glioma still remain largely unknown. Amounting evidence highlights the critical regulatory function of miRNAs in carcinogenesis. Here, we showed that the expression of miR-150-3p was significantly decreased in glioma tissues and cell lines. Suppressed expression of miR-150-3p was associated with the lymph node metastasis of the glioma patients. Overexpression of miR-150-3p significantly inhibited the proliferation of glioma cells. Molecular study uncovered that the transcription factor specificity protein 1 (SP1) was identified as one of the targets of miR-150-3p Highly expressed miR-150-3p in glioma cells significantly decreased both the mRNA and protein levels of SP1. Consistently, the abundance of phosphatase and tension homolog deleted on chromosome ten (PTEN), a negative downstream target of SP1, was increased with the ectopic miR-150-3p Collectively, these results suggested that miR-150-3p suppressed the growth of glioma cells partially via regulating SP1 and possibly PTEN.

MicroRNA-424/E2F6 feedback loop modulates cell invasion, migration and EMT in endometrial carcinoma

Our previous study explored the roles of microRNA-424 (miR-424) in the development of endometrial carcinoma (EC) and analyzed the miR-424/E2F7 axis in EC cell growth. In this study, we investigated the status of miR-424 in human endometrial cancer tissues, which were collected from a cohort of Zunyi patients. We found that the expression level of miR-424 was associated with clinical tumor stage, cell differentiation, lymph node metastasis and cell migration ability. Cell function experiments demonstrated that miR-424 overexpression suppressed the invasion and migration abilities of endometrial carcinoma cells in vitro. Bioinformatic predictions and dual-luciferase reporter assays suggested E2F6 as a possible target of miR-424. RT-PCR and western blot assays demonstrated that miR-424 transfection reduced the expression level of E2F6, while inhibiting miR-424 with ASO-miR-424 (antisense oligonucleotides of miR-424) increased the expression level of E2F6. Cell function experiments indicated that E2F6 transfection rescued the EC cell phenotype induced by miR-424. In addition, we also found that E2F6 negatively regulated miR-424 expression in EC cells. In summary, our results demonstrated that the miR-424/E2F6 feedback loop modulates cell invasion, migration and EMT in EC and that the miR-424/E2Fs regulation network may serve as a new and potentially important therapeutic target in EC.