The MicroRNA-217 Functions as a Potential Tumor Suppressor in Gastric Cancer by Targeting GPC5

Epithelial-mesenchymal transition-related long noncoding RNAs in gastric carcinoma

As an evolutionarily phenotypic conversion program, the epithelial-mesenchymal transition (EMT) has been implicated in tumour deterioration and has facilitated the metastatic ability of cancer cells via enhancing migration and invasion. Gastric cancer (GC) remains a frequently diagnosed non-skin malignancy globally. Most GC-associated mortality can be attributed to metastasis. Recent studies have shown that EMT-related long non-coding RNAs (lncRNAs) play a critical role in GC progression and GC cell motility. In addition, lncRNAs are associated with EMT-related transcription factors and signalling pathways. In the present review, we comprehensively described the EMT-inducing lncRNA molecular mechanisms and functional perspectives of EMT-inducing lncRNAs in GC progression. Taken together, the statements of this review provided a clinical implementation in identifying lncRNAs as potential therapeutic targets for advanced GC.

iGRLCDA: identifying circRNA-disease association based on graph representation learning

While the technologies of ribonucleic acid-sequence (RNA-seq) and transcript assembly analysis have continued to improve, a novel topology of RNA transcript was uncovered in the last decade and is called circular RNA (circRNA). Recently, researchers have revealed that they compete with messenger RNA (mRNA) and long noncoding for combining with microRNA in gene regulation. Therefore, circRNA was assumed to be associated with complex disease and discovering the relationship between them would contribute to medical research. However, the work of identifying the association between circRNA and disease in vitro takes a long time and usually without direction. During these years, more and more associations were verified by experiments. Hence, we proposed a computational method named identifying circRNA-disease association based on graph representation learning (iGRLCDA) for the prediction of the potential association of circRNA and disease, which utilized a deep learning model of graph convolution network (GCN) and graph factorization (GF). In detail, iGRLCDA first derived the hidden feature of known associations between circRNA and disease using the Gaussian interaction profile (GIP) kernel combined with disease semantic information to form a numeric descriptor. After that, it further used the deep learning model of GCN and GF to extract hidden features from the descriptor. Finally, the random forest classifier is introduced to identify the potential circRNA-disease association. The five-fold cross-validation of iGRLCDA shows strong competitiveness in comparison with other excellent prediction models at the gold standard data and achieved an average area under the receiver operating characteristic curve of 0.9289 and an area under the precision-recall curve of 0.9377. On reviewing the prediction results from the relevant literature, 22 of the top 30 predicted circRNA-disease associations were noted in recent published papers. These exceptional results make us believe that iGRLCDA can provide reliable circRNA-disease associations for medical research and reduce the blindness of wet-lab experiments.

The novel lncRNA GPC5-AS1 stabilizes GPC5 mRNA by competitively binding with miR-93/106a to suppress gastric cancer cell proliferation

Long non-coding RNAs (lncRNAs) are of importance in the genesis and progression of gastric cancer (GC). GPC5-AS1 is a novel lncRNA associated with methyl-CpG-binding protein 2 (MeCP2), identified in our previous microarray analysis; however, the role of GPC5-AS1 in GC remains unknown. In the present study, we demonstrate that GPC5-AS1 is downregulated in GC cells and tissues, and this aberrant expression is regulated by MeCP2 through CpG site binding in the promoter region. Importantly, we also demonstrate that GPC5-AS1 overexpression suppresses cell proliferation, colony formation, and cell cycle transition; induces apoptosis in vitro; and inhibits tumorigenicity in vivo. The expression of the controversial gene GPC5 was downregulated in GC tissues, and elevated GPC5 level could inhibit GC cell growth. Mechanistically, we demonstrated that GPC5-AS1 stabilizes GPC5 mRNA by acting as a molecular sponge for miR-93 and miR-106a, thereby reducing GC tumor progression. In conclusion, our results suggest that GPC5-AS1 may play a pivotal role in GC and serve as a potential diagnostic biomarker and a powerful therapeutic target for GC.

MicroRNA-217: a therapeutic and diagnostic tumor marker

INTRODUCTION

Cancer as one of the most common causes of death has always been one of the major health challenges globally. Since, the identification of tumors in the early tumor stages can significantly reduce mortality rates; it is required to introduce novel early detection tumor markers. MicroRNAs (miRNAs) have pivotal roles in regulation of cell proliferation, migration, apoptosis, and tumor progression. Moreover, due to the higher stability of miRNAs than mRNAs in body fluids, they can be considered as non-invasive diagnostic or prognostic markers in cancer patients.

AREAS COVERED

In the present review we have summarized the role of miR-217 during tumor progressions. The miR-217 functions were categorized based on its target molecular mechanisms and signaling pathways.

EXPERT OPINION

It was observed that miR-217 mainly exerts its function by regulation of the transcription factors during tumor progressions. The WNT, MAPK, and PI3K/AKT signaling pathways were also important molecular targets of miR-217 in different cancers. The present review clarifies the molecular biology of miR-217 and paves the way of introducing miR-217 as a non-invasive diagnostic marker and therapeutic target in cancer therapy.

Bladder mesenchymal stromal cell-derived exosomal miRNA-217 modulates bladder cancer cell survival through Hippo-YAP pathway

BACKGROUND

Donor cell-derived exosomes regulate recipient cell functions. The aim of this study was to investigate the effect of human normal bladder stromal cell (hBSC) derived exosomal miR-217 on bladder cell cancer proliferation and migration.

METHODS

Human BSCs were transfected with miR-217 mimic or inhibitor and hBSC-derived exosomes were isolated. Human bladder cancer cell lines (T24 and 5367) were co-cultured with hBSC-derived exosomal miR-217 mimic or inhibitor. Proliferation, migration, and apoptosis of the bladder cancer cells were assessed by Edu assay, Transwell migration assay, and Annexin V assay.

RESULTS

Expression of miR-217 was significantly higher in the T24 and 5367 cell lines (P < 0.01). Exosomal miR-217 mimic enhanced proliferation and migration of T24 and 5367 cells, but inhibited apoptosis of the cells (P < 0.01); in contrast, exosomal miR-217 inhibitor suppressed proliferation and migration but stimulated apoptosis of the two cancer cell lines (P < 0.01). Moreover, exosomal miR-217 mimic stimulated YAP and its target proteins including Cyr61, CTGF, and ANKRD1 (P < 0.01), and in contrast, exosomal miR-217 inhibitor suppressed YAP and its target proteins (P < 0.01).

CONCLUSION

These findings suggested that hBSC-derived exosomal miR-217 may act as oncogene in bladder cancer cells, and that Hippo-YAP signaling pathway maybe the target for miR-217 in the bladder cancer cell lines.

MiR-450a-5p Inhibits Gastric Cancer Cell Proliferation, Migration, and Invasion and Promotes Apoptosis via Targeting CREB1 and Inhibiting AKT/GSK-3β Signaling Pathway

Gastric cancer seriously affects human health and research on gastric cancer is attracting more and more attentions. In recent years, molecular targets have become the research focus. Accumulating evidence indicates that miR-450a-5p plays a critical role in cancer progression. However, the biological role of miR-450a-5p in gastric carcinogenesis remains largely unknown. In this study, we explore the effects and mechanisms of miR-450a-5p on the development and progression of gastric cancer. We used gain-of-function approaches to investigate the role of miR-450a-5p on gastric cancer cell proliferation, migration, invasion, and apoptosis using biological and molecular techniques including real-time quantitative PCR (RT-qPCR), CCK-8, colony formation, flow cytometry, Western blot, wound healing, transwell chamber, dual luciferase reporter, and tumor xenograft mouse model. We found that gastric cancer cells have low expression of miR-450a-5p and overexpression of miR-450a-5p inhibited gastric cancer cell proliferation, migration and invasion, and induced apoptosis in vitro. Moreover, we demonstrated that ectopic expression of miR-450a-5p inhibited gastric cancer growth in vivo. At the molecular level, overexpression of miR-450a-5p significantly increased the expression of pro-apoptotic proteins, including caspase-3, caspase-9, and Bax, and inhibited the expression of anti-apoptotic protein Bcl-2. Luciferase reporter experiment suggested that camp response element binding protein 1 (CREB1) had a negative correlation with miR-450a-5p expression, and knockdown of CREB1 alleviated gastric cancer growth. Furthermore, we also found that miR-450a-5p inhibited the activation of AKT/GSK-3β signaling pathway to inhibit the progression of gastric cancer. Collectively, miR-450a-5p repressed gastric cancer cell proliferation, migration and invasion and induced apoptosis through targeting CREB1 by inhibiting AKT/GSK-3β signaling pathway. MiR-450a-5p could be a novel molecular target for the treatment of gastric cancer.

Hedgehog signaling activation required for glypican-6-mediated regulation of invasion, migration, and epithelial-mesenchymal transition of gastric cancer cells

Gastric cancer (GC) is the fifth most common cancer worldwide and one of the most aggressive cancers in China. Glypican 6 is highly expressed in gastric adenocarcinoma and may act as a diagnostic and prognostic marker; however, the functional importance and molecular mechanism of glypican 6 in GC remains unclear. In the current study, we aimed to reveal the function and mechanism of glypican 6 in two GC cell lines: MKN-45 and SGC-7901. We found higher expression of glypican 6 in MKN-45 and SGC-7901 cells than in cells from the normal gastric mucosa epithelial cell line GES-1. Glypican 6 knockdown suppressed MKN-45 and SGC-7901 cell proliferation. A Transwell assay confirmed that glypican 6 silencing inhibited the migration and invasiveness of MKN-45 and SGC-7901 cells. Epithelial-to-mesenchymal transition (EMT) markers were determined by western blotting, and the results showed reduced Vimentin expression and elevated E-cadherin expression in glypican 6 short interfering RNA (siRNA) transfected MKN-45 and SGC-7901 cells. However, glypican 6 overexpression in GES-1 cells showed no significant promotion on GES-1 cells proliferation and migration. Further studies confirmed that glypican 6 siRNA regulated Hedgehog and Gli1 signaling and participated in the function of glypican 6 on MKN-45 and SGC-7901 cell migration and invasion. Our findings suggest that decreased glypican 6 expression inhibits the migration and invasion ability of GC cells.

Influence of miR-376c-3p/SYF2 Axis on the Progression of Gastric Cancer

MicroRNA-376c-3p was previous reported to have a crucial role in the progression of human cancer. This study was aimed to investigate the influence of microRNA-376c-3p on the proliferation and migration of human gastric cancer cells and the associated mechanism. We explored the expression of microRNA-376c-3p in gastric cancer cells using reverse transcription-quantitative polymerase chain reaction. Also, we analyzed the association and biological significance of microRNA-376c-3p and SYF2 pre-mRNA-splicing factor in gastric cancer. MicroRNA-376c-3p expression was found downregulated in gastric cancer cell lines compared to the normal cell line. MicroRNA-376c-3p directly targeted SYF2 and reduced SYF2 expression. Overexpression of microRNA-376c-3p inhibits gastric cancer cell proliferation and migration. Besides that, overexpression of SYF2 abrogates the inhibitory influences on gastric cancer cell behaviors caused by microRNA-376c-3p mimic. These results showed that microRNA-376c-3p inhibits the proliferation and migration of gastric cancer cells via targeting SYF2.

Correlation between FAK and EGF-Induced EMT in Colorectal Cancer Cells

Epithelial-mesenchymal transition (EMT) plays an important role in the invasion and metastasis of colorectal cancer, which is mediated by FAK and EGF. However, whether FAK participates in EMT in colorectal cancer cells through the EGF/EGFR signaling pathway remains unknown. The aim of this study was to investigate the effector mechanisms of FAK in the process of EGF-induced EMT in colorectal cancer cells and to determine whether miR-217 is involved in this process. Caco-2 cancer cells were routinely cultured with and without treatment with 100 ng/mL EGF, and changes in cell morphology were observed using an inverted microscope. In addition, a transwell assay was used to detect cell migration under the condition of EGF treatment. The expression of FAK, pFAK, E-cadherin, vimentin, and β actin was assessed by western blotting, and the expression of miR-217 was assessed using real-time PCR. We found that EGF induced EMT in colorectal cancer cells and enhanced cell migration and invasion ability. Moreover, FAK was involved in the EGF-induced EMT of colorectal cancer cells. EGF upregulated the expression of E-cadherin in colorectal cancer cells by activating FAK, and miR-217 was found to participate in EGF-induced EMT in colorectal cancer cells. Our findings indicate that EGF induces EMT in colorectal cancer cells by activating FAK, and miR-217 is involved in the EGF/FAK/E-cadherin signaling pathway.

MiR-217 Inhibits Proliferation, Migration, and Invasion by Targeting SIRT1 in Osteosarcoma

Purpose: Many studies have revealed that microRNAs (miRNAs) play crucial roles in cancer development and progression. miRNA-217 (miR-217) has been implicated in various cancers. However, the role of miR-217 in osteosarcoma (OS) remains unclear. In this study, the authors examined the role of miR-217 in development of OS. Materials and Methods: Using quantitative real-time PCR, they assessed expression levels of miR-217 in cultured cells and patient samples and examined the proliferation, migration, and invasion of cultured cells by MTT cell proliferation assays, cell scratch test, and cell transwell test. The proliferation, migration, and invasion were examined for MG63 and U2OS transfected by miR-217. Silent information regulator 2 homolog 1 (SIRT1) overexpression plasmid was designed. Results: Expression of miR-217 was downregulated in samples of OS tissue and cultured cells. Proliferation, migration, and invasion were inhibited by ectopic overexpression of miR-217. SIRT1 was identified as targets of miR-217. Expression levels of SIRT1 were inhibited by miR-217 expression in cultured cells, and the expression levels of miR-217 and SIRT1 were inversely correlated in patients with OS. Conclusion: MiR-217 acts as a tumor suppressor in the development of OS. The tumor-suppressive function of miR-217 in OS suggests inhibition of SIRT1.

Identification and functional analysis of microRNAs in rats following focal cerebral ischemia injury

MicroRNA sequencing (miRNA‑seq) was performed in the present study to investigate miRNA expression profiles in infarcted brain areas following focal cerebral ischemia induced by middle cerebral artery occlusion in rats. In total, 20 miRNAs were identified to be upregulated and 17 to be downregulated in the infarct area. The expression levels of six differentially expressed miRNAs (DEmiRs), miR‑211‑5p, miR‑183‑5p, miR‑10b‑3p, miR‑182, miR‑217‑5p and miR‑96‑5p, were examined by reverse transcription‑​quantitative polymerase chain reaction. Subsequently, a miRNA‑mRNA network was constructed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to investigate the functions of the mRNAs targeted by these DEmiRs. The present study aimed to investigate the association between miRNAs and cerebral ischemia to provide potential insight into the molecular mechanisms underlying ischemic stroke.

HOTAIR enhanced paclitaxel and doxorubicin resistance in gastric cancer cells partly through inhibiting miR-217 expression

Drug resistance is a big obstacle for clinical anti-tumor treatment outcome. However, the role of HOTAIR in drug resistance in gastric cancer (GC) remains unknown. In this study, we showed that overexpression of HOTAIR enhanced paclitaxel and doxorubicin resistance in GC cells. Furthermore, the expression of HOTAIR was upregulated in GC tissues and higher expression of HOTAIR was associated with late stage. In addition, we showed that miR-217 expression was lower in GC tissues compared with the paired non-tumour tissues and downregulated expression of miR-217 was correlated with late stage. Interestingly, the expression of miR-217 was negatively correlated with HOTAIR expression in GC tissues. Ectopic expression of HOTAIR increased GC cell proliferation, cell cycle, and migration. Elevated expression of HOTAIR suppressed miR-217 expression and enhanced GPC5 and PTPN14 expression. Furthermore, we demonstrated that overexpression of miR-217 suppressed paclitaxel and doxorubicin resistance in GC cells. Ectopic expression of HOTAIR promoted drug resistance and increased GC cell proliferation, cell cycle, and migration by targeting miR-217. These data suggested that overexpression of HOTAIR enhanced paclitaxel and doxorubicin resistance in GC cells through inhibiting miR-217 expression.

MicroRNAs as potential therapeutics to enhance chemosensitivity in advanced prostate cancer

Docetaxel and cabazitaxel are taxane chemotherapy treatments for metastatic castration-resistant prostate cancer (CRPC). However, therapeutic resistance remains a major issue. MicroRNAs are short non-coding RNAs that can silence multiple genes, regulating several signalling pathways simultaneously. Therefore, synthetic microRNAs may have therapeutic potential in CRPC by regulating genes involved in taxane response and minimise compensatory mechanisms that cause taxane resistance. To identify microRNAs that can improve the efficacy of taxanes in CRPC, we performed a genome-wide screen of 1280 microRNAs in the CRPC cell lines PC3 and DU145 in combination with docetaxel or cabazitaxel treatment. Mimics of miR-217 and miR-181b-5p enhanced apoptosis significantly in PC3 cells in the presence of these taxanes. These mimics downregulated at least a thousand different transcripts, which were enriched for genes with cell proliferation and focal adhesion functions. Individual knockdown of a selection of 46 genes representing these transcripts resulted in toxic or taxane sensitisation effects, indicating that these genes may be mediating the effects of the microRNA mimics. A range of these genes are expressed in CRPC metastases, suggesting that these microRNA mimics may be functional in CRPC. With further development, these microRNA mimics may have therapeutic potential to improve taxane response in CRPC patients.

Overexpression of Glypican 5 (GPC5) Inhibits Prostate Cancer Cell Proliferation and Invasion via Suppressing Sp1-Mediated EMT and Activation of Wnt/β-Catenin Signaling

Glypican 5 (GPC5) belongs to the family of heparan sulfate proteoglycans (HSPGs). It was initially known as a regulator of growth factors and morphogens. Recently, there have been reports on its correlation with the tumorigenic process in the development of some cancers. However, little is known about its precise role in prostate cancer (PCa). In the present study, we explored the expression pattern and biological functions of GPC5 in PCa cells. Our results showed that GPC5 was lowly expressed in PCa cell lines. Upregulation of GPC5 significantly inhibited PCa cell proliferation and invasion in vitro as well as attenuated tumor growth in vivo. We also found that overexpression of GPC5 inhibited the epithelial-mesenchymal transition (EMT) and Wnt/β-catenin signaling activation, which was mediated by Sp1. Taken together, we suggest GPC5 as a tumor suppressor in PCa and provide promising therapeutic strategies for PCa.

A novel regulatory function for miR-217 targetedly suppressing fibronectin expression in keloid fibrogenesis

Fibronectin (FN) plays a critical role in the development and progression of keloid scarring (KS). In the present study, we hypothesized that a post-translational mechanism of microRNAs regulated the expression of FN in keloid scarring fibroblasts (KSFBs). Here, we collected 20 KS tissues and paired corresponding adjacent normal tissues from clinical patients and measured the expression of miRNA-217. First, by using PicTar, TargetScan and miRBase database, we found that miRNA-217 might be a regulator of FN in human species. Based on these hypotheses, the expression of miRNA-217 and FN in KS tissues was investigated. The results demonstrated that the expression of miRNA-217 was greatly suppressed, and FN was increased in KS tissues. Intriguingly, the expression levels of endogenous miRNA-217 negatively correlated with the FN mRNA levels (Pearson's correlation coefficient = -0.683, P < 0.001). In vitro, miRNA-217 could regulate FN through the predicted binding sites in its 3'-UTR. miRNA-217 played an impact on cell proliferation and apoptosis, thereby regulating KSFBs growth. Moreover, miRNA-217 gain-of function decreased FN, Col-1 and Col-3 protein expression, and miRNA-217 loss-of function increased FN, Col-1 and Col-3 protein expression in KSFBs. In conclusion, overexpressed miRNA-217 could inhibit KSFBs growth, and the underlying mechanism was mediated, at least partially, through the suppression of FN expression. But above all, miRNA-217 might play a potential therapeutic avenue for the treatment of keloid fibrogenesis.

Circular RNAs: Biogenesis, Function, and a Role as Possible Cancer Biomarkers

Circular RNAs (circRNAs) are a class of noncoding RNAs (ncRNAs) that form covalently closed continuous loop structures, lacking the terminal 5' and 3' ends. CircRNAs are generated in the process of back-splicing and can originate from different genomic regions. Their unique circular structure makes circRNAs more stable than linear RNAs. In addition, they also display insensitivity to ribonuclease activity. Generally, circRNAs function as microRNA (miRNA) sponges and have a regulatory role in transcription and translation. They may be also translated in a cap-independent manner in vivo, to generate specific proteins. In the last decade, next-generation sequencing techniques, especially RNA-seq, have revealed great abundance and also dysregulation of many circRNAs in various diseases, suggesting their involvement in disease development and progression. Regarding their high stability and relatively specific differential expression patterns in tissues and extracellular environment (e.g., body fluids), they are regarded as promising novel biomarkers in cancer. Therefore, we focus this review on describing circRNA biogenesis, function, and involvement in human cancer development and address the potential of circRNAs to be effectively used as novel cancer diagnostic and prognostic biomarkers.

Polymorphisms of rs1347093 and rs1397529 are associated with lung cancer risk in northeast Chinese population

Lung cancer is one of the malignant tumors with the highest morbidity and mortality all over the world. Here we researched the association between two SNPs (rs1347093 in MIR217HG and rs1397529 in Gab1) and the risk of lung cancer in northeast Chinese population, including 825 cases and 766 controls. We carried out χ2 test, unconditional logistic regression analysis and crossover analysis to estimate the relationship between SNPs and lung cancer risk and the interaction between SNPs and smoking on susceptibility to lung cancer. The results indicated that rs1347093, rs1397529 polymorphisms were associated with lung cancer risk, especially with adenocarcinoma risk. Dominant genetic model of the rs1347093 was associated with reduced risk of lung cancer compared to CC genotype (AC+AA vs. CC: adjusted OR = 0.599, 95%CI = 0.418-0.858, P=0.005). For rs1347093, the similar result was found. Dominant genetic model of the rs1397529 was associated with reduced risk of lung cancer compared to AA genotype (AC+CC vs. AA: adjusted OR = 0.664, 95%CI = 0.491-0.897, P=0.008). There is no significant interaction between rs1347093, rs1397529 polymorphism and smoking on susceptibility to lung cancer. Our study might demonstrate that rs1347093 in MIR217HG and rs1397529 in Gab1 could be meaningful as the novel biomarker for lung cancer risk.

miR-217-5p induces apoptosis by directly targeting PRKCI, BAG3, ITGAV and MAPK1 in colorectal cancer cells

Apoptosis is a genetically directed process of programmed cell death. A variety of microRNAs (miRNAs), endogenous single-stranded non-coding RNAs of about 22 nucleotides in length have been shown to be involved in the regulation of the intrinsic or extrinsic apoptotic pathways. There is increasing evidence that the aberrant expression of miRNAs plays a causal role in the development of diseases such as cancer. This makes miRNAs promising candidate molecules as therapeutic targets or agents. MicroRNA (miR)-217-5p has been implicated in carcinogenesis of various cancer entities, including colorectal cancer. Here, we analyzed the pro-apoptotic potential of miR-217-5p in a variety of colorecatal cancer cell lines showing that miR-217-5p mimic transfection led to the induction of apoptosis causing the breakdown of mitochondrial membrane potential, externalization of phosphatidylserine, activation of caspases and fragmentation of DNA. Furthermore, elevated miR-217-5p levels downregulated mRNA and protein expression of atypical protein kinase c iota type I (PRKCI), BAG family molecular chaperone regulator 3 (BAG3), integrin subunit alpha v (ITGAV) and mitogen-activated protein kinase 1 (MAPK1). A direct miR-217-5p mediated regulation to those targets was shown by repressed luciferase activity of reporter constructs containing the miR-217-5p binding sites in the 3' untranslated region. Taken together, our observations have uncovered the apoptosis-inducing potential of miR-217-5p through its regulation of multiple target genes involved in the ERK-MAPK signaling pathway by regulation of PRKCI, BAG3, ITGAV and MAPK1.

MIR-519d suppresses the gastric cancer epithelial-mesenchymal transition via Twist1 and inhibits Wnt/β-catenin signaling pathway

MicroRNAs (miRNAs) deregulation is frequent in human gastric cancer (GC). MiR-519d has been reported to function as tumor suppressor microRNA in some tumors. However, the role of miR-519d in GC progression remains unclear. In the study, we demonstrated that the expression of miR-519d was down-regulated in gastric cancer tissues and cell lines, and lower miR-519d expression was associated with distant metastasis, lymph node metastasis and clinical stage for patients with GC. Univariate and multivariate Cox analysis showed that lower miR-519d expression was positively associated with shorter disease-free survival (DFS) and the over survival (OS) time for GC patients and was an independent predictor. Kaplan-Meier curve and log-rank test also demonstrated that lower miR-519d had a poor shorter DFS and OS for GC patients. Function analysis showed that the inhibition of miR-519d expression was able to promote the cell proliferation, migration and invasion and over-expression of miR-519d in GC cells had inhibited effects. Moreover, we demonstrated that over-expression of miR-519d significantly inhibited the process of epithelial mesenchymal transition (EMT) in GC cells and miR-519d can directly target at 3'-untranslation region of Twist1 and regulate its expression. We also demonstrated that miR-519d could suppress the Wnt/β-catenin signaling pathway in GC cells. In vivo, we showed that miR-519d inhibited the tumor growth. Thus, our results suggested that miR-519d functioned as a tumor suppressor in GC and could be a promising therapeutic target for GC.

MicroRNA dysregulation in the tumor microenvironment influences the phenotype of pancreatic cancer

Cellular interactions in the tumor microenvironment influence neoplastic progression in pancreatic ductal adenocarcinoma. One underlying mechanism is the induction of the prognostically unfavorable epithelial-mesenchymal-transition-like tumor budding. Our aim is to explore the expression of microRNAs implicated in the regulation of tumor budding focusing on the microenvironment of the invasive front. To this end, RNA from laser-capture-microdissected material of the main tumor, tumor buds, juxta-tumoral stroma, tumor-remote stroma, and non-neoplastic pancreatic parenchyma from pancreatic cancer cases with (n=7) and without (n=6) tumor budding was analyzed by qRT-PCR for the expression of a panel of miRNAs that are known to be implicated in the regulation of epithelial-mesenchymal transition, including miR-21, miR-183, miR-200b, miR-200c, miR-203, miR-205, miR-210, and miR-217. Here we show that at the invasive front of pancreatic ductal adenocarcinoma, specific microRNAs, are differentially expressed between tumor buds and main tumor cells and between cases with and without tumor budding, indicating their involvement in the regulation of the budding phenotype. Notably, miR-200b and miR-200c were significantly downregulated in the tumor buds. Consistent with this finding, they negatively correlated with the expression of epithelial-mesenchymal-transition-associated E-cadherin repressors ZEB1 and ZEB2 in the budding cells (P<0.001). Interestingly, many microRNAs were also dysregulated in juxta-tumoral compared to tumor-remote stroma suggesting that juxta-tumoral stroma contributes to microRNA dysregulation. Notably, miR-200b and miR-200c were strongly downregulated while miR-210 and miR-21 were upregulated in the juxta-tumoral vs tumor-remote stroma in carcinomas with tumor budding. In conclusion, microRNA targeting in both tumor and stromal cells could represent a treatment option for aggressive pancreatic cancer.

The lncRNA MALAT1 acts as a competing endogenous RNA to regulate KRAS expression by sponging miR-217 in pancreatic ductal adenocarcinoma

The long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript-1 (MALAT1) has been shown to play an important role in tumourigenesis. The aim of this study was to investigate the role of MALAT1 in pancreatic ductal adenocarcinoma. MALAT1 is expressed at higher levels in pancreatic ductal adenocarcinoma (PDAC) tissues than in nontumour tissues and in metastatic PDAC than in localized tumours. Patients with PDAC and high MALAT1 expression levels have shorter overall survival than patients with PDAC and low MALAT1 expression levels. Knocking down MALAT1 reduces pancreatic tumour cell growth and proliferation both in vitro and in vivo. Moreover, MALAT1 knockdown inhibits cell cycle progression and impairs tumour cell migration and invasion. We found that miR-217 can bind MALAT1 and regulate its expression in PDAC cell lines. We also found MALAT1 knockdown attenuates the protein expression of KRAS, a known target of miR-217. After MALAT1 knockdown, KRAS protein expression levels can be rescued through inhibition of miR-217 expression. More importantly, MALAT1 knockdown does not directly affect cellular miR-217 expression but decreases the miR-217 nucleus/cytoplasm ratio, suggesting that MALAT1 inhibits the translocation of miR-217 from the nucleus to the cytoplasm.

Noncoding RNA in drug resistant sarcoma

Sarcomas are a group of malignant tumors that arise from mesenchymal origin. Despite significant development of multidisciplinary treatments for sarcoma, survival rates have reached a plateau. Chemotherapy has been extensively used for sarcoma treatment; however, the development of drug resistance is a major obstacle limiting the success of many anticancer agents. Sarcoma biology has traditionally focused on genomic and epigenomic deregulation of protein-coding genes to identify the therapeutic potential for reversing drug resistance. New and more creative approaches have found the involvement of noncoding RNAs, including microRNAs and long noncoding RNAs in drug resistant sarcoma. In this review, we discuss the current knowledge of noncoding RNAs characteristics and the regulated genes involved in drug resistant sarcoma, and focus on their therapeutic potential in the future.

MicroRNA 217 inhibits cell proliferation and enhances chemosensitivity to doxorubicin in acute myeloid leukemia by targeting KRAS

Acute myeloid leukemia (AML) is a heterogeneous malignant disorder derived from the myeloid hematopoietic cells that accounts for ~80% of all adult acute leukemia. Numerous studies have shown that drug resistance not only exists against conventional chemotherapeutic drugs, but also limits the efficacy of new biological agents. Therefore, it is important to identify the mechanisms behind chemoresistance and seek therapeutic strategies to enhance efficacy in AML chemotherapy. MicroRNA (miR)-217 has been recognized as a tumor suppressor that is downregulated in various types of cancer, however the mechanisms behind the expression and function of miR-217 in AML have not yet been recognized. The expression of miR-217 was determined by quantitative polymerase chain reaction (qPCR). Following transfection with miR-217 mimics, an MTT assay, chemosensitivity assay, cell apoptosis assay and western blot analysis were performed in AML cell lines. Functional assays were also performed to explore the effects of endogenous Kirsten rat sarcoma viral oncogene homolog (KRAS) in AML. The results revealed that miR-217 was downregulated in patients with AML. Overexpression of miR-217 inhibited cellular proliferation and enhanced cell chemosensitivity to doxorubicin by the cell apoptosis pathway in AML cells. A dual-luciferase reporter assay demonstrated that KRAS was a direct target gene of miR-217 in vitro. qPCR and western blot analysis revealed that miR-217 negatively regulated KRAS protein expression, but had no impact on KRAS mRNA expression. Knockdown of KRAS expression markedly suppressed AML cellular proliferation, and enhanced cell chemosensitivity to doxorubicin via the cell apoptosis pathway. These findings indicate that miR-217 functions as a tumor suppressor in AML by directly targeting KRAS. Therefore, miR-217-based therapeutic strategies may provide a novel strategy for the enhancement of efficacy in the treatment of AML.

TTBK2 circular RNA promotes glioma malignancy by regulating miR-217/HNF1β/Derlin-1 pathway

BACKGROUND

Circular RNAs are a subgroup of non-coding RNAs and generated by a mammalian genome. Herein, the expression and function of circular RNA circ-TTBK2 were investigated in human glioma cells.

METHODS

Fluorescence in situ hybridization and quantitative real-time PCR were conducted to profile the cell distribution and expression of circ-TTBK2 and microRNA-217 (miR-217) in glioma tissues and cells. Immunohistochemical and western blot were used to determine the expression of HNF1β and Derlin-1 in glioma tissues and cells. Stable knockdown of circ-TTBK2 or overexpression of miR-217 glioma cell lines (U87 and U251) were established to explore the function of circ-TTBK2 and miR-217 in glioma cells. Further, luciferase reports and RNA immunoprecipitation were used to investigate the correlation between circ-TTBK2 and miR-217. Cell Counting Kit-8, transwell assays, and flow cytometry were used to investigate circ-TTBK2 and miR-217 function including cell proliferation, migration and invasion, and apoptosis, respectively. ChIP assays were used to ascertain the correlations between HNF1β and Derlin-1.

RESULTS

We found that circ-TTBK2 was upregulated in glioma tissues and cell lines, while linear TTBK2 was not dysregulated in glioma tissues and cells. Enhanced expression of circ-TTBK2 promoted cell proliferation, migration, and invasion, while inhibited apoptosis. MiR-217 was downregulated in glioma tissues and cell lines. We also found that circ-TTBK2, but not linear TTBK2, acted as miR-217 sponge in a sequence-specific manner. In addition, upregulated circ-TTBK2 decreased miR-217 expression and there was a reciprocal negative feedback between them in an Argonaute2-dependent manner. Moreover, reintroduction of miR-217 significantly reversed circ-TTBK2-mediated promotion of glioma progression. HNF1β was a direct target of miR-217, and played oncogenic role in glioma cells. Remarkably, circ-TTBK2 knockdown combined with miR-217 overexpression led to tumor regression in vivo.

CONCLUSIONS

These results demonstrated a novel role circ-TTBK2 in the glioma progression.

miR-216b Targets FGFR1 and Confers Sensitivity to Radiotherapy in Pancreatic Ductal Adenocarcinoma Patients Without EGFR or KRAS Mutation

OBJECTIVES

The success of gemcitabine plus radiotherapy is dependent on the mutation status of pancreatic ductal adenocarcinoma (PDAC) tumors in the EGFR and KRAS genes; however, radiotherapy resistance may also be modulated epigenetically by microRNA (miRNA) regulation. In this study, we examined the potential effect of miRNAs on the resistance to radiotherapy in cases without EGFR or KRAS mutation.

METHODS

The association of EGFR and KRAS mutation status and different expression patterns of 6 selected miRNAs related to the EGFR/KRAS signaling pathway were evaluated in the tumors of 42 patients with PDAC.

RESULTS

Reduced miR-216b and miR-217 expression was associated with aggressive tumor characteristics and shortened disease-free survival. In addition, miR-216b expression was reduced 2.7-fold in the cases that did not benefit from therapy, although they did not demonstrate EGFR or KRAS expression (P = 0.0316). A negative correlation between FGFR1 and miR-216b expression (r = -0.355) was found in the tumors of these cases.

CONCLUSIONS

Further studies and validations are required; in the tumors of patients with PDAC without activating mutations and induced expression of EGFR/KRAS genes, down-regulated miR-216b expression may be associated with a poor response to radiotherapy via deregulation of another signaling pathway related to FGFR1 signaling.

Glypican-5 is a tumor suppressor in non-small cell lung cancer cells

Glypican-5 (GPC5) belongs to the glypican family of proteoglycans that have been implicated in a variety of physiological processes, ranging from cell proliferation to morphogenesis. However, the role of GPC5 in human cancer remains poorly understood. We report that knockdown of GPC5 in bronchial epithelial cells promoted, and forced expression of GPC5 in non-small lung cancer (NSCLC) cells suppressed, the anchorage-independent cell growth. In vivo, expression of GPC5 inhibited xenograft tumor growth of NSCLC cells. Furthermore, we found that GPC5 was expressed predominantly as a membrane protein, and its expression led to diminished phosphorylation of several oncogenic receptor tyrosine kinases, including the ERBB family members ERBB2 and ERBB3, which play critical roles in lung tumorigenesis. Collectively, our results suggest that GPC5 may act as a tumor suppressor, and reagents that activate GPC5 may be useful for treating NSCLC.

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GPC5 suppresses anchorage-independent growth of lung cancer cells.

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GPC5 suppresses xenograft growth of lung cancer cells.

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GPC5 is localized to the membrane and suppresses oncogenic RTKs.

Comparative analysis of the small RNA transcriptomes of miiuy croaker revealed microRNA-mediated regulation of TLR signaling pathway response to Vibrio anguillarum infection

MicroRNAs (miRNAs) are an abundant class of endogenous noncoding small RNAs (sRNAs) that are partially complementary to their target messenger RNA (mRNA), which post-transcriptionally regulate various biological processes by repressing mRNA translation or inducing mRNA degradation. MiRNAs have been demonstrated to play crucial roles in the host response to infection by diverse pathogens. As an important bacterial pathogen, Vibrio anguillarum has been caused great economic losses in miiuy croaker aquaculture. To identify immune-related miRNAs of miiuy croaker in response to V. anguillarum infection, we constructed two sRNA libraries with or without bacterial infection. High-throughput deep sequencing and subsequent bioinformatic analysis identified 241 conserved and 137 novel miRNA precursors in miiuy croaker based on its whole genome sequences, encoding 293 and 124 mature miRNAs, respectively. Then we compared the expression patterns of miRNAs in the two libraries. There were significant differences in the expression of 12 miRNAs between the infection group (IG) and control group (CG). Further, the expressions of six miRNAs were validated by real-time quantitative PCR. The target gene prediction and function analysis were conducted for the 12 differential miRNAs. This analysis revealed that these miRNAs participated in the regulation multiple immune-related signaling pathways. Transcription factors in TLR signaling, such as AP-1, IRF5, NF-κB and IRF3, were activated by these miRNAs via post-transcriptionally regulating the expression of TLRs and TLR-associated signaling proteins, inducing effective host immune response to eradicate infectious pathogens. This is the first study of the identification and characterization of miiuy croaker miRNAs in response to V. anguillarum infection. The comprehensive analysis of the expression of miRNAs and the target gene and function prediction of differently expressed miRNAs may help to understand the regulatory mechanisms of miRNA in fish during the interaction between host and bacterial pathogens.

MicroRNA-193b inhibits the proliferation, migration and invasion of gastric cancer cells via targeting cyclin D1

MicroRNAs have been involved in RNA silencing and post-transcriptional regulation of gene expression and also play important roles in tumorigenesis and tumor progression. MiR-193b was previously reported to act as tumor suppressor in diverse cancers. However, little is known about the expression, function and mechanism of miR-193b in gastric cancer (GC). In this study, we investigated the expression of miR-193b in 50 GC cases and found that miR-193b was significantly reduced in GC tissues compared with the adjacent normal gastric tissues. Moreover, lower-level of miR-193b was also associated with a more aggressive GC phenotype. We further demonstrated that miR-193b can inhibit the proliferation, migration and invasion of HGC-27 and MGC-803 GC cells. Further mechanism study indicated that CCND1 was a direct target of miR-193b in GC. Overexpression of miR-193b inhibited the expression of CCND1, and knock-down of CCND1 inhibited the proliferation of GC cells, suggesting that miR-193b exerted its anti-tumorigenic role in GC cells through targeting CCND1 gene.