Regulation of microRNAs function by circular RNAs in human cancer

circRNA-SMO upregulates CEP85 to promote proliferation and migration of glioblastoma via sponging miR-326

Circular RNAs (circRNAs) play an important role in cancer development by sponging microRNAs (miRNAs) to regulate the signaling axis. However, more comprehensive mechanisms of circRNAs in glioblastoma need to be elucidated. RT-qPCR was used to detect the expression levels of circRNA-SMO and miR-326. Dual-luciferase reporter assays were conducted to verify the interaction among circRNA-SMO, miR-326, and CEP85. Flow cytometric analysis was performed to detect apoptosis. Western blotting was used to determine the protein levels of the different molecules. Animal xenograft experiments were performed to evaluate the role of circRNA-SMO in vivo. CircRNA-SMO was upregulated in glioblastoma tissues and glioblastoma cells. CircRNA-SMO downregulation inhibited the viability and colony-forming ability of the glioblastoma cells. In addition, miR-326 was downregulated in glioblastoma cells, which was verified to sponge circRNA-SMO and interact with CEP85. Moreover, circRNA-SMO inhibition induced the elevation of miR-326 and apoptosis, accompanied by a decrease in CEP85. CircRNA-SMO knockdown-mediated tumor inhibition was prevented by an miR-326 inhibitor. Furthermore, circRNA-SMO inhibition inhibited tumor growth in vivo, accompanied by an increase in miR-326 and a decline in CEP85 in tumor tissues. Conclusions. CircRNA-SMO sponges miR-326 to promote glioblastoma proliferation and migration by upregulating CEP85 expression. This study clarified the role of circRNA-SMO in the development of glioblastoma, providing novel insights for its treatment.

Screening differential circular RNA expression profiles and the potential role of hsa_circ_0085465 in liver cancer

Aims

This study aimed to screen the circular RNAs (circRNAs) that are differentially expressed between liver cancer and paired paracarcinoma tissues and then elucidate their role in cancer progression.

Materials and Methods

High-throughput sequencing of cancer and paired paracarcinoma tissues was followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of the parental genes of the differentially expressed circRNAs, which were also verified via real-time quantitative polymerase chain reaction analysis of the tissues. In addition, the function of selected circRNAs was determined using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4- sulfophenyl)-2H-tetrazolium (MTS) and transwell assays.

Results

Total 218 and 121 circRNAs were differentially upregulated and downregulated, respectively; these were mainly enriched with GO and KEGG terms related to biological functions. From five representatives of the differentially expressed circRNAs, we selected hsa_circ_0085465 for further analysis, discovering that its overexpression promoted the proliferation, migration, and invasion of 97 L cells.

Conclusion

Taken together, our results suggest that hsa_circ_0085465 is relevant to liver cancer progression.

The Role of miRNA-221 and miRNA-34a in Non-Melanoma Skin Cancer of the Head and Neck Region

Non-melanoma skin cancer (NMSC) is one of the most frequent types of malignancy in the human body with an increasing incidence. Short, non-coding RNA molecules called microRNAs (miRNAs) can control post-transcriptional gene expression and they have a significant role in several physiological cellular processes and pathologies, including cancer. Depending on the functions of the genes, miRNAs may function as oncogenes or tumor suppressors. The aim of this paper was to describe the role of miRNA-34a and miRNA-221 in head and neck NMSC. Thirty-eight NMSC match paired (tumor and adjacent) tissue samples were evaluated by qRT-PCR. Total RNA was extracted and isolated from tissue samples using the phenol-chloroform (Trireagent) method according to the manufacturer's protocol. The concentration of RNA was measured by a NanoDrop-1000 spectrophotometer. The expression level of each miRNA was calculated by threshold cycle. For all statistical tests, the 0.05 significance level was used and two-tailed p values. All analyses were conducted in an R environment for statistical computing and graphics. We found the miRNA-221 being overexpressed in squamous cell carcinoma (SCC) (p < 0.05), basal cell carcinoma (BCC) and basosquamous cell carcinoma (BSC) compared with adjacent normal tissue. Additionally, the levels of miRNA-221 were two times higher (p < 0.05) in cases where the excision of the tumor was done with positive margins (R1), which means that we are the first to highlight the potential role of miRNA-221 in the microscopical local invasion. Mi-RNA-34a expression was altered in the malignant tissue compared with the adjacent normal one both in BCC and SCC but not statistically significantly. In conclusion, NMSC are challenging because of their increasing incidence and rapidly evolving development and discovering their molecular mechanisms of action lead us to understand tumorigenesis and evolution, while also contributing to the implementation of novel therapeutic keys.

Study on the Mechanism of circRNA Regulating the miRNA Level in Nephrotic Syndrome

Background

Nephrotic syndrome is an enormous public healthy threaten, which causes a variety of complications and secondary disease; however, the molecular mechanism of nephrotic syndrome remains unclear.

Methods

In our study, RNA-seq were used to test the transcription level of patients with nephrotic syndrome, in order to investigate the interaction of circRNA-miRNA-mRNA in nephrotic syndrome patients.

Results

Consistent with our hypothesis, miRNAs were confirmed to be associated with nephrotic syndrome, majority of their targeting circRNAs downregulated in nephrotic syndrome patients and at the same time, the KEGG pathway analysis found that target genes of the circRNAs bonding miRNAs was highly correlated with the occurrence of kidney diseases.

Conclusion

Thus, we can draw a conclusion that downregulated circRNAs cause miRNA expressing aberrant and then affect the expression level of mRNA, finally leading to the generation of nephrotic syndrome.

Mir-29a Promotes the Migration of Bone Marrow Mesenchymal Stem Cells to Oral Squamous Cell Carcinoma Cells

Oral squamous cell carcinoma (OSCC) is a tumor in the oral cavity and around oral mucosa. Mir-29a level was differentially expressed in OSCC patients. However, whether its exact role and function in OSCC remains to be further elucidated. Our study investigated the effect of Mir-29a on the migration of bone marrow mesenchymal stem cells (BMSCs) to oral squamous cell carcinoma cells (OSCCs). Mir-29a level was measured in OSCCs and BMSCs by real-time quantitative PCR and its relationship with Panc-1 was verified by dual luciferase reporter gene. After up-regulation of Mir-29a or treatment with Panc-1 siRNA, BMSCs migration to OSCCs was assessed by transwell assay and Panc-1 and Mir-29a were measure. Mir-29a level was downregualted in OSCCs and Panc-1 was upregulated in BMSCs. Panc-1 and Mir-29a was negatively correlated and Mir-29a could bind and target Panc-1. Down-regulation of Panc-1 inhibited the migration of BMSCs to OSCCs and elevated Mir-29a level promoted cell migration. After co-transfection of Mir-29a inhibitor and Panc-1 siRNA, the inhibited cell migration function can be restored. In conclusion, Mir-29a promotes the migration of BMSCs to OSCCs through targeting Panc-1.

circ_0089153 exacerbates breast cancer cells proliferation and metastasis via sponging miR-2467-3p/E2F6

The role of circ_0089153 in breast cancer (BCa) malignancy development was explored. circ_0089153 expression in BCa was analyzed by Gene Expression Omnibus database. Clinical tissues were obtained from 90 BCa patients. Cell counting kit-8 assay, 5-ethnyl-2 deoxyuridine assay and colony formation experiment were applied for proliferation detection. Wound healing assay and Transwell experiment were used for migration and invasion detection. Dual luciferase reporter gene assay, RNA immunoprecipitation assay and RNA pull-down assay were conducted. In vivo growth and metastasis of BCa cells were performed. Quantitative real-time polymerase chain reaction, Western blot and immunohistochemistry were applied for RNAs and proteins expression. The up-modulated circ_0089153 indicated an unfavorable survival of BCa patients. circ_0089153 knockdown attenuated BCa cells proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) (P < .01). circ_0089153 was miR-2467-3p sponge. Low miR-2467-3p expression indicated a worse survival of BCa patients. miR-2467-3p overexpression reduced BCa cells proliferation, migration, invasion and EMT (P < .05). circ_0089153 enhanced BCa cells proliferation, migration, invasion and EMT by sponging miR-2467-3p (P < .05). E2F6 was directly suppressed by miR-2467-3p. E2F6 high expression in BCa patients associated with worse survival. circ_0089153 knockdown suppressed in vivo BCa cells growth and lung metastasis (P < .01). circ_0089153 was an oncogene in breast cancer, which enhanced proliferation and metastasis through sponging miR-2467-3p/E2F6. circ_0089153 was suggested to be a potential target for BCa target treatment.

Endogenous miRNA Sponges

MicroRNAs (miRNAs) are a class of noncoding RNAs of 17-22 nucleotides in length with a critical function in posttranscriptional gene regulation. These master regulators are themselves subject to regulation both transcriptionally and posttranscriptionally. Recently, miRNA function has been shown to be modulated by exogenous RNA molecules that function as miRNA sponges. Interestingly, endogenous transcripts such as transcribed pseudogenes, long noncoding RNAs (lncRNAs), circular RNAs (circRNAs) and mRNAs may serve as natural miRNA sponges. These transcripts, which bind to miRNAs and competitively sequester them away from their targets, are naturally existing endogenous miRNA sponges, called competing endogenous RNAs (ceRNAs). Here we present a historical background of miRNAs, exogenous and endogenous miRNA sponges as well as some examples of endogenous miRNA sponges involved in regulatory mechanisms associated with various diseases, developmental stages, and other cellular processes.

Is miRNA Regulation the Key to Controlling Non-Melanoma Skin Cancer Evolution?

Non melanoma skin cancer (NMSC) is one of the most common types of skin cancer. It has a number of subtypes, which include basal cell carcinoma, cutaneous squamous cell carcinoma and Merkel cell carcinoma. MicroRNAs are short, non-coding RNA (ribonucleic acid) molecules, capable of regulating gene expression at a post transcriptional level. They play a pivotal role in a variety of physiologic cellular functions and pathologies, including malignant diseases. The development of miRNAs represents an important study field, which has been extensively exploited in melanoma for almost a decade with promising results, therefore we consider it a stepstone for further research projects also in non-melanoma skin cancers. The aim of our study was to explore the current literature in order to present the role of the different miRNAs in some of the most frequent types of NMSC pertaining to oncogenesis, evolution and therapy. The most relevant and accurate available data from the literature were evaluated. Our study concluded that there are almost 100 miRNAs which can be upregulated or downregulated and can play a role in oncogenesis. They can be easily identified in circulation, are stable and they can be important diagnosis/prognosis and therapy monitoring markers.

CircTP63 promotes cell proliferation and invasion by regulating EZH2 via sponging miR-217 in gallbladder cancer

Background

Gallbladder cancer (GBC) is the most common biliary tract malignancy and has a poor prognosis in patients with GBC. CircRNA TP63 (circTP63) has been implicated in cell proliferation and invasion in some tumor progress. The study aims to investigate the clinical significance and functional role of circTP63 expression in GBC.

Methods

The expression of circTP63 in GBC tissues or cells was detected by qRT-PCR and the association between circTP63 expression and prognosis of GBC patients was analyzed. CCK8 assay, flow cytometry analysis, transwell assay and in vivo studies were used to evaluate the cell proliferation and invasion abilities after circTP63 knockdown in GBC cells. Luciferase reporter assays and RNA pull-down assay were used to determine the correlation between circTP63 and miR-217 expression. Besides, western blot analysis was also performed.

Results

In the present study, we showed that circTP63 expression was upregulated in GBC tissues and cells. Higher circTP63 expression was associated with lymph node metastasis and short overall survival (OS) in patients with GBC. In vitro, knockdown of circTP63 significantly inhibited cell proliferation, cell cycle progression, migration and invasion abilities in GBC. Besides, we demonstrated that knockdown of circTP63 inhibited GBC cells Epithelial-Mesenchymal Transition (EMT) process. In vivo, knockdown of circTP63 inhibited tumor growth in GBC. Mechanistically, we demonstrated that circTP63 competitively bind to miR-217 and promoted EZH2 expression and finally facilitated tumor progression.

Conclusions

Our findings demonstrated that circTP63 sponged to miR-217 and regulated EZH2 expression and finally facilitated tumor progression in GBC. Thus, targeting circTP63 may be a therapeutic strategy for the treatment of GBC.

Research Progress on Circular RNA in Glioma

The discovery of circular RNA (circRNA) greatly complements the traditional gene expression theory. CircRNA is a class of non-coding RNA with a stable cyclic structure. They are highly expressed, spatiotemporal-specific and conservative across species. Importantly, circRNA participates in the occurrence of many kinds of tumors and regulates the tumor development. Glioma is featured by limited therapy and grim prognosis. Cancer-associated circRNA compromises original function or creates new effects in glioma, thus contributing to oncogenesis. Therefore, this article reviews the biogenesis, metabolism, functions and properties of circRNA as a novel potential biomarker for gliomas. We elaborate the expression characteristics, interaction between circRNA and other molecules, aiming to identify new targets for early diagnosis and treatment of gliomas.

Vascular Dysfunction in Preeclampsia

Preeclampsia is a life-threatening pregnancy-associated cardiovascular disorder characterized by hypertension and proteinuria at 20 weeks of gestation. Though its exact underlying cause is not precisely defined and likely heterogenous, a plethora of research indicates that in some women with preeclampsia, both maternal and placental vascular dysfunction plays a role in the pathogenesis and can persist into the postpartum period. Potential abnormalities include impaired placentation, incomplete spiral artery remodeling, and endothelial damage, which are further propagated by immune factors, mitochondrial stress, and an imbalance of pro- and antiangiogenic substances. While the field has progressed, current gaps in knowledge include detailed initial molecular mechanisms and effective treatment options. Newfound evidence indicates that vasopressin is an early mediator and biomarker of the disorder, and promising future therapeutic avenues include mitigating mitochondrial dysfunction, excess oxidative stress, and the resulting inflammatory state. In this review, we provide a detailed overview of vascular defects present during preeclampsia and connect well-established notions to newer discoveries at the molecular, cellular, and whole-organism levels.

Liquid biopsy approach to pancreatic cancer

Pancreatic cancer (PC) continues to pose a major clinical challenge. There has been little improvement in patient survival over the past few decades, and it is projected to become the second leading cause of cancer mortality by 2030. The dismal 5-year survival rate of less than 10% after the diagnosis is attributable to the lack of early symptoms, the absence of specific biomarkers for an early diagnosis, and the inadequacy of available chemotherapies. Most patients are diagnosed when the disease has already metastasized and cannot be treated. Cancer interception is vital, actively intervening in the malignization process before the development of a full-blown advanced tumor. An early diagnosis of PC has a dramatic impact on the survival of patients, and improved techniques are urgently needed to detect and evaluate this disease at an early stage. It is difficult to obtain tissue biopsies from the pancreas due to its anatomical position; however, liquid biopsies are readily available and can provide useful information for the diagnosis, prognosis, stratification, and follow-up of patients with PC and for the design of individually tailored treatments. The aim of this review was to provide an update of the latest advances in knowledge on the application of carbohydrates, proteins, cell-free nucleic acids, circulating tumor cells, metabolome compounds, exosomes, and platelets in blood as potential biomarkers for PC, focusing on their clinical relevance and potential for improving patient outcomes.

Recent research progress on circular RNAs: Biogenesis, properties, functions, and therapeutic potential

Circular RNAs (circRNAs), an emerging family member of RNAs, have gained importance in research due to their new functional roles in cellular physiology and disease progression. circRNAs are usually available in a wide range of cells and have shown tissue-specific expression as well as developmental specific expression. circRNAs are characterized by structural stability, conservation, and high abundance in the cell. In this review, we discuss the different models of biogenesis. The properties of circRNAs such as localization, structure and conserved pattern, stability, and expression specificity are also been illustrated. Furthermore, we discuss the biological functions of circRNAs such as microRNA (miRNA) sponging, cell cycle regulation, cell-to-cell communication, transcription regulation, translational regulation, disease diagnosis, and therapeutic potential. Finally, we discuss the recent research progress and future perspective of circRNAs. This review provides an understanding of potential diagnostic markers and the therapeutic potential of circRNAs, which are emerging daily.

CircTHBS1 targeting miR-211/CCND2 pathway to promote cell proliferation and migration potential in primary cystitis glandularis cells

The pathogenesis of cystitis glandular (CG) is unclear, but it is generally considered to be a neoplastic lesion of urothelial hyperplasia formed by long-term chronic stimulation. There is growing evidence that circRNAs play important roles in a variety of cellular processes. However, there are few reports on the role and molecular mechanism of circRNA in CG. In the present study, we first isolated primary cells from CG tissues and adjacent normal tissues. Further experiments showed that CircTHBS1 was up-regulated in primary CG cells (pCGs). The results of CCK-8 showed that the overexpression of CircTHBS1 promoted the viability of pCGs, while the deletion of CircTHBS1 reduced the cell viability. Knocking out CircTHBS1 also inhibited the migration of pCGs. In addition, we demonstrated that CircTHBS1 played a role in the adsorption of miR-211 by “sponge” in pCG. In turn, miR-211 can directly target CYCLIN D2 (CCND2) 3′UTR to perform its function. Finally, we confirmed the role and mechanism of CircTHBS1/miR-211/CCND2 regulation axis in pCGs. In summary, our study is the first to reveal the role and underlying mechanism of CircTHBS1 in CG, providing a potential biomarker and therapeutic target for human CG.

CircCNIH4 inhibits gastric cancer progression via regulating DKK2 and FRZB expression and Wnt/β-catenin pathway

Background

Circular RNAs (circRNAs) have been reported to play an important role in tumor progression in various cancer types, including gastric cancer. The aim of this study was to investigate the role of circCNIH4 (hsa_circ_0000190) in gastric cancer and the underlying mechanism.

Methods

The expression levels of circCNIH4 and Wnt antagonist genes were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of β-catenin, Ki67, Dickkopf 2 (DKK2) and Frizzled related protein (FRZB) were measured by western blot. Ectopic overexpression or knockdown of circCNIH4, proliferation, apoptosis, migration and invasion by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), flow cytometry and transwell assay in vitro, and in vivo experiment, were employed to assess the role of circCNIH4 in gastric cancer.

Results

CircCNIH4 was downregulated in gastric cancer tissues and cells. Overexpression of circCNIH4 inhibited gastric cancer cell proliferation, migration and invasion and promoted apoptosis by inactivating Wnt/β-catenin pathway in vitro. CircCNIH4 induced the expression of DKK2 and FRZB in gastric cancer cells. Moreover, silencing of DKK2 or FRZB reversed circCNIH4 overexpression-mediated effects on gastric cancer cells. Additionally, circCNIH4 suppressed tumor growth via regulating DKK2 and FRZB expression in gastric cancer in vivo.

Conclusion

Our study demonstrated that circCNIH4 played a tumor-inhibiting role through upregulating DKK2 and FRZB expression and suppressing Wnt/β-catenin pathway in gastric cancer, which might provide a potential biomarker for the diagnosis and treatment of gastric cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40709-021-00140-x.

Double matrix completion for circRNA-disease association prediction

BACKGROUND

Circular RNAs (circRNAs) are a class of single-stranded RNA molecules with a closed-loop structure. A growing body of research has shown that circRNAs are closely related to the development of diseases. Because biological experiments to verify circRNA-disease associations are time-consuming and wasteful of resources, it is necessary to propose a reliable computational method to predict the potential candidate circRNA-disease associations for biological experiments to make them more efficient.

RESULTS

In this paper, we propose a double matrix completion method (DMCCDA) for predicting potential circRNA-disease associations. First, we constructed a similarity matrix of circRNA and disease according to circRNA sequence information and semantic disease information. We also built a Gauss interaction profile similarity matrix for circRNA and disease based on experimentally verified circRNA-disease associations. Then, the corresponding circRNA sequence similarity and semantic similarity of disease are used to update the association matrix from the perspective of circRNA and disease, respectively, by matrix multiplication. Finally, from the perspective of circRNA and disease, matrix completion is used to update the matrix block, which is formed by splicing the association matrix obtained in the previous step with the corresponding Gaussian similarity matrix. Compared with other approaches, the model of DMCCDA has a relatively good result in leave-one-out cross-validation and five-fold cross-validation. Additionally, the results of the case studies illustrate the effectiveness of the DMCCDA model.

CONCLUSION

The results show that our method works well for recommending the potential circRNAs for a disease for biological experiments.

Hsa-circRNA-103809 Promotes Hepatocellular Carcinoma Development via MicroRNA-1270/PLAG1 Like Zinc Finger 2 Axis

BACKGROUND

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death in the worldwide. A great number of reports manifested that circular RNA hsa-circRNA-103809 (circRNA-103809) could work in several cancers.

AIMS

This study aimed to explore the function and mechanism of circRNA-103809 in HCC.

METHODS

Gene expressions were detected by quantitative real-time polymerase chain reaction. Colony formation, cell counting kit-8, transwell and wound healing assays were implemented to check the role of circRNA-103809 in HCC. Subcellular fractionation analysis was designed to figure out the cellular location of circRNA-103809. Luciferase reporter assay and RNA pull down assay were employed to verify the relationships among RNAs.

RESULTS

CircRNA-103809 was highly expressed in HCC cell lines. After interfering circRNA-103809, the proliferation, migration, invasion and epithelial-to-mesenchymal transition process were all hindered in HCC cells. Significantly, circRNA-103809 competed with PLAG1 like zinc finger 2 (PLAGL2) for binding with microRNA-1270 (miR-1270), which formulated a competing endogenous RNA network in HCC. Thereafter, we verified the tumor-facilitating effect of circRNA-103809/miR-1270/PLAGL2 axis on biological behaviors of HCC cells.

CONCLUSION

Hsa-circRNA-103809 promoted development of HCC via sequestering miR-1270 and up-regulating PLAGL2.

Regulatory mechanisms, functions, and clinical significance of CircRNAs in triple-negative breast cancer

Circular RNAs (circRNAs) are a new class of endogenous regulatory RNAs characterized by covalently closed cyclic structure lacking poly-adenylated tails, and are capable of regulating gene expression at transcription or post-transcription levels. Recently, plentiful circRNAs have been discovered in breast cancer and some circRNAs expression profiles are specifically involved in the triple-negative breast cancer (TNBC). TNBC is a type of malignant tumor defined by the lack of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 expression. Considering its clinical characteristics of high invasion, metastasis, poor prognosis, and lack of effective response to conventional chemotherapies or targeted therapies, it could be a promosing option to discover specific circRNAs as new targets for TNBC treatment. Meanwhile, accumulating evidence has demonstrated that circRNAs are dysregulated in TNBC tissues and are correlated with clinicopathological features and prognosis of TNBC patients. Furthermore, looking for circRNAs with high specificity and sensitivity will provide a new opportunity for the early diagnosis, clinical treatment, and prognosis monitoring of TNBC. Herein, we reviewed the biogenesis, regulatory mechanisms, and biological functions of circRNAs in TNBC and summarized the relationship between circRNAs expression and the clinicopathology, diagnosis, and prognosis of patients with TNBC.

Integration of transcriptomes analysis with spectral signature of total RNA for generation of affordable remote sensing of Hepatocellular carcinoma in serum clinical specimens

Hepatocellular carcinoma (HCC) is a major global health problem with about 841,000 new cases and 782,000 deaths annually, due to lacking early biomarker/s, and centralized diagnosis. Transcriptomes research despite its infancy has proved excellence in its implementation in identifying a coherent specific cancer RNAs differential expression. However, results are sometimes overlapped by other cancer types which negatively affecting specificity, plus the high cost of the equipment used. Hyperspectral imaging (HSI) is an advanced tool with unique, spectroscopic features, is an emerging tool that has widely been used in cancer detection. Herein, a pilot study has been performed for HCC diagnosis, by exploiting HIS properties and the analysis of the transcriptome for the development of non-invasive remote HCC sensing. HSI data cube images of the sera extracted total RNA have been analyzed in HCC, normal subject, liver benign tumor, and chronic HCV with cirrhotic/non-cirrhotic liver groups. Data analyses have revealed a specific spectral signature for all groups and can be easily discriminated; at the computed optimum wavelength. Moreover, we have developed a simple setup based on a commercial laser pointer for sample illumination and a Smartphone CCD camera, with HSI consistent data output. We hypothesized that RNA differential expression and its spatial organization/folding are the key players in the obtained spectral signatures. To the best of our knowledge, we are the first to use HSI for sensing cancer based on total RNA in serum, using a Smartphone CCD camera/laser pointer. The proposed biosensor is simple, rapid (2 min), and affordable with specificity and sensitivity of more than 98% and high accuracy.

CircRNA EPHB4 modulates stem properties and proliferation of gliomas via sponging miR-637 and up-regulating SOX10

Gliomas are the most common type of primary brain tumors. CircRNA ephrin type-B receptor 4 (circEPHB4) is a circular RNA derived from the receptor tyrosine kinase EPHB4. However, the clinical significance and the specific roles of circEPHB4 in gliomas and glioma cancer stem cells (CSC) have not been studied. Here, we found that circEPHB4 (hsa_circ_0081519) and SOX10 were up-regulated and microRNA (miR)-637 was down-regulated in glioma tissues and cell lines. Consistently, circEPHB4 was positively correlated with SOX10 but negatively correlated with miR-637. The altered expressions of these molecules were independently associated with overall survival of patients. CircEPHB4 up-regulated SOX10 and Nestin by directly sponging miR-637, thereby stimulating stemness, proliferation and glycolysis of glioma cells. Functionally, silencing circEPHB4 or increasing miR-637 levels in glioma cells was sufficient to inhibit xenograft growth in vivo. In conclusion, the circEPHB4/miR-637/SOX10/Nestin axis plays a central role in controlling stem properties, self-renewal and glycolysis of glioma cells and predicts the overall survival of glioma patients. Targeting this axis might provide a therapeutic strategy for malignant gliomas.

Circular RNAs in stem cell differentiation: a sponge-like role for miRNAs

Circular RNAs (circRNAs) are novel endogenous non-coding RNAs that play a critical role during cellular signal transduction, gene transcription and translation. With the rapid advancement of bioinformatics analysis tools and high-throughput RNA sequencing, numerous circRNAs with important biological features have been identified. They function as competing endogenous RNAs (ceRNAs) of microRNAs and as such exhibit the potential to act as biomarkers for stem cell differentiation. In the recent past, several studies have shown the involvement of circRNAs in stem cells differentiation. The present review summarizes the molecular characteristics, biogenesis and mechanisms of newly identified circRNAs in the differentiation of stem cells. In conclusion, circRNAs regulate the stem cells differentiation via their ambient binding efficacy to modulate miRNA expression, as well as related gene translation. We believe that this review will provide reference guidance for future studies on stem cell differentiation.

Potential circRNA-disease association prediction using DeepWalk and network consistency projection

A growing body of experimental studies have reported that circular RNAs (circRNAs) are of interest in pathogenicity mechanism research and are becoming new diagnostic biomarkers. As experimental techniques for identifying disease-circRNA interactions are costly and laborious, some computational predictors have been advanced on the basis of the integration of biological features about circRNAs and diseases. However, the existing circRNA-disease relationships are not well exploited. To solve this issue, a novel method named DeepWalk and network consistency projection for circRNA-disease association prediction (DWNCPCDA) is proposed. Specifically, our method first reveals features of nodes learned by the deep learning method DeepWalk based on known circRNA-disease associations to calculate circRNA-circRNA similarity and disease-disease similarity, and then these two similarity networks are further employed to feed to the network consistency projection method to predict unobserved circRNA-disease interactions. As a result, DWNCPCDA shows high-accuracy performances for disease-circRNA interaction prediction: an AUC of 0.9647 with leave-one-out cross validation and an average AUC of 0.9599 with five-fold cross validation. We further perform case studies to prioritize latent circRNAs related to complex human diseases. Overall, this proposed method is able to provide a promising solution for disease-circRNA interaction prediction, and is capable of enhancing existing similarity-based prediction methods.

circ_SEPT9, a newly identified circular RNA, promotes oral squamous cell carcinoma progression through miR-1225/PKN2 axis

Circular RNAs (circRNAs) represent a newly discovered class of endogenous non-coding RNAs which are widely expressed and play important roles in disease progression. However, the function of circRNAs in oral squamous cell carcinoma (OSCC) still remains largely unknown. In this research, we found that circ_SEPT9 was highly expressed in OSCC cell lines and tumour tissues. Results showed that circ_SEPT9 promoted OSCC proliferation and tumour growth. And, circ_SEPT9 also enhanced the migration and invasion of OSCC cells. Mechanically, we found that circ_SEPT9 acted as a sponge for miR-1225 to rescue PKN2 expression in OSCC cells. Inhibition of circ_SEPT9/miR-1225/PKN2 pathway could effectively block the proliferation and metastasis of OSCC cells. Our study provides strong evidence that circ_SEPT9/miR-1225/PKN2 axis is a promising target for OSCC treatment.

Circular RNA hsa_circ_0004277 contributes to malignant phenotype of colorectal cancer by sponging miR-512-5p to upregulate the expression of PTMA

In recent years, extensive reports have been published concerning the molecular mechanism underlying the occurrence and progression of colorectal cancer. Circular RNAs (circRNAs) have been identified as important modulators in the biological processes of colorectal cancer. Microarray analysis unveiled that differential circ-0004277 expression was identified in tissue samples of colorectal cancer. High circ-0004277 expression was then verified in tissue samples and cell lines of colorectal cancer via qRT-PCR. Kaplan-Meier analysis was used for identifying the association between circ-0004277 expression and the overall survival rate of colorectal cancer patients. A relationship existed between higher circ-0004277 expression and decreased overall survival rate of colorectal cancer patients. From a functional perspective, circ-0004277 knockdown accelerated cell apoptosis and restrained cell proliferation of colorectal cancer. From mechanistic perspective, circ-0004277 upregulated PTMA by sponging miR-512-5p. Rescue assay was used for verifying the roles of the circ-0004277-miR-512-5p-PTMA axis. Both miR-512-5p and PTMA participated in circ-0004277-mediated colorectal cancer cell proliferation based on experiments. In summary, our study showed that circ-0004277 promoted the proliferation of colorectal cancer cells as a miR-512-5p sponge to upregulate the PTMA expression.

Circular RNAs-The Road Less Traveled

Circular RNAs are the most recent addition in the non-coding RNA family, which has started to gain recognition after a decade of obscurity. The first couple of reports that emerged at the beginning of this decade and the amount of evidence that has accumulated thereafter has, however, encouraged RNA researchers to navigate further in the quest for the exploration of circular RNAs. The joining of 5′ and 3′ ends of RNA molecules through backsplicing forms circular RNAs during co-transcriptional or post-transcriptional processes. These molecules are capable of effectively sponging microRNAs, thereby regulating the cellular processes, as evidenced by numerous animal and plant systems. Preliminary studies have shown that circular RNA has an imperative role in transcriptional regulation and protein translation, and it also has significant therapeutic potential. The high stability of circular RNA is rendered by its closed ends; they are nevertheless prone to degradation by circulating endonucleases in serum or exosomes or by microRNA-mediated cleavage due to their high complementarity. However, the identification of circular RNAs involves diverse methodologies and the delineation of its possible role and mechanism in the regulation of cellular and molecular architecture has provided a new direction for the continuous research into circular RNA. In this review, we discuss the possible mechanism of circular RNA biogenesis, its structure, properties, degradation, and the growing amount of evidence regarding the detection methods and its role in animal and plant systems.

Epigenetics of Bladder Cancer: Where Biomarkers and Therapeutic Targets Meet

Bladder cancer (BC) is the most common neoplasia of the urothelial tract. Due to its high incidence, prevalence, recurrence and mortality, it remains an unsolved clinical and social problem. The treatment of BC is challenging and, although immunotherapies have revealed potential benefit in a percentage of patients, it remains mostly an incurable disease at its advanced state. Epigenetic alterations, including aberrant DNA methylation, altered chromatin remodeling and deregulated expression of non-coding RNAs are common events in BC and can be driver events in BC pathogenesis. Accordingly, these epigenetic alterations are now being used as potential biomarkers for these disorders and are being envisioned as potential therapeutic targets for the future management of BC. In this review, we summarize the recent findings in these emerging and exciting new aspects paving the way for future clinical treatment of this disease.

CircRhoC promotes tumorigenicity and progression in ovarian cancer by functioning as a miR-302e sponge to positively regulate VEGFA

Ovarian cancer is a leading cause of deaths due to gynaecological malignancy. While endogenous non‐coding circular RNAs (circRNAs) in cancer have attracted attention, their roles in ovarian cancer are not known. We used qRT‐PCR to quantify expression of circRhoC in ovarian cancer tissues and normal tissues. The effects of overexpressing or destruction of circRhoC on the phenotype of ovarian cancer cells were assessed both in vitro and in vivo. Dual‐luciferase reporter assay assesses the microRNA sponge function of circRhoC. Western blotting was used to confirm the effects of circRhoC and microRNA on target gene expression. Our results showed that circRhoC was significantly up‐regulated in ovarian cancer tissues compared to normal ovarian tissues. Overexpression of circRhoC in CAOV3 ovarian cancer cell increased cell viability, migration and invasion ability; destroying circRhoC in A2780 had the opposite effects and inhibited ovarian tumour cell A2780 dissemination in the peritoneum in vivo. We confirmed circRhoC functions as a sponge for miR‐302e to positively regulate VEGFA; FISH experiments showed that circRhoC could co‐focal with miR‐302e; besides, overexpression of miR‐302e reversed the ability of circRhoC to positively regulate VEGFA, and what's more, RIP assay showed that circRhoC could directly bind with VEGFA; besides, VEGFA expression level in ovarian cancer tissues was positively associated with circRhoC expression. In conclusion, the oncogenic effect of RhoC in ovarian cancer is at least in part due to circRhoC, which functions not only as a miR‐302e sponge to positively regulate VEGFA protein expression, but may also directly bind and modulate VEGFA expression.

Exosome circ_0044516 promotes prostate cancer cell proliferation and metastasis as a potential biomarker

Circular RNAs (circRNAs) are important regulators in cancer growth and progression. Exosomes carry various molecules including RNA, protein, and lipid from one cell to another cell. But the role of circRNAs from the exosomes from prostate cancer patients are not elucidated. In this study, circ_0044516 was found upregulated in prostate cancer and the roles and molecular mechanism of Hsa_circ_0044516 (circ_0044516) was investigated. Firstly, the exosomes of prostate cancer patients were collected for human circRNAs microarray to screen the circRNA expression profile. There were 35 significantly expressed circRNAs with more than fivefolds from microarray analysis. Circ_0044516 was verified to be significantly upregulated in the exosomes from prostate cancer patients and the cell lines. Further investigation demonstrated that circ_0044516 downregulation inhibited the proliferation and metastasis of prostate cancer cells. By bioinformatics and luciferase reporter assays, circ_0044516 was verified to downregulate miR-29a-3p expression and negatively related to miR-29a-3p expression levels in prostate cancer. In a summary, the study indicated that circ_0044516 played an important role in prostate cancer cell survival and metastasis, which suggested that an oncogenic role of circ_0044516 in prostate cancer.

Circ_0039569 promotes renal cell carcinoma growth and metastasis by regulating miR-34a-5p/CCL22

Circular RNAs (circRNAs) belong to non-coding RNAs and are known as key regulators in gene regulation. CircRNAs involve in the various biological processes of cancer. However, the functions of circRNAs in renal cell carcinoma (RCC) are still not clear. In this study, the circRNA expression profile was performed in the RCC tissues by microarray. There were 35 significantly expressed circRNAs with more than 5 folds from microarray analysis. Hsa_circ_0039569 (circ_0039569) was verified to be up-regulated in RCC and cells compared with the controls by real time RT-PCR. The assays of cellular functions showed that circ_0039569 down-regulation suppressed the proliferation and metastasis of RCC cells. The molecular mechanism of circ_0039569 in RCC cells showed that circ_0039569 promoted RCC progression by up-regulating CCL22 expression via down-regulating miR-34a-5p. Taken together, the study indicated that circ_0039569 played an important role in RCC cell survival and metastasis, which suggested that an oncogenic role of circ_0039569 in RCC progression.

Viroid research and its significance for RNA technology and basic biochemistry

Viroids were described 47 years ago as the smallest RNA molecules capable of infecting plants and autonomously self-replicating without an encoded protein. Work on viroids initiated the development of a number of innovative methods. Novel chromatographic and gelelectrophoretic methods were developed for the purification and characterization of viroids; these methods were later used in molecular biology, gene technology and in prion research. Theoretical and experimental studies of RNA folding demonstrated the general biological importance of metastable structures, and nuclear magnetic resonance spectroscopy of viroid RNA showed the partially covalent nature of hydrogen bonds in biological macromolecules. RNA biochemistry and molecular biology profited from viroid research, such as in the detection of RNA as template of DNA-dependent polymerases and in mechanisms of gene silencing. Viroids, the first circular RNA detected in nature, are important for studies on the much wider spectrum of circular RNAs and other non-coding RNAs.

kshv-mir-k12-1-5p promotes cell growth and metastasis by targeting SOCS6 in Kaposi's sarcoma cells

Background: Kaposi’s sarcoma (KS) is a highly disseminated angiogenic tumour of endothelial cells. Many deregulated miRNAs, including kshv-mir-k12-1-5p, have been identified in KS. kshv-mir-k12-1-5p plays important roles in KS. However, the underlying mechanism is not fully understood. The aim of this study was to investigate the exact functions of kshv-mir-k12-1-5p in KS cells.

Materials and methods: The biological functions of kshv-mir-k12-1-5p were studied using CCK-8, apoptosis, migration and invasion assays. Bioinformatics software was used to identify the target gene (SOCS6) of kshv-mir-k12-1-5p. A dual luciferase assay, Western blot (WB) and quantitative real-time polymerase chain reaction (q-PCR) were performed to further verify the target gene. The underlying molecular mechanisms of kshv-mir-k12-1-5p in KS cells were also explored.

Results: kshv-mir-k12-1-5p can promote the proliferation, migration and invasion of KS cells and inhibit cell apoptosis. Suppressor of cytokine signalling 6 (SOCS6) was identified as a direct target of kshv-mir-k12-1-5p, and kshv-mir-k12-1-5p can downregulate SOCS6 expression. In addition, knockdown of SOCS6 rescued the effects of kshv-mir-k12-1-5p inhibitor. Hence, a direct relationship between kshv-mir-k12-1-5p and SOCS6 was confirmed.

Conclusions: kshv-mir-k12-1-5p promotes the malignant phenotype of KS cells by targeting SOCS6, suggesting that kshv-mir-k12-1-5p could be a potential therapeutic target for KS.

The Diagnostic and Prognostic Value of miR-200c in Gastric Cancer: A Meta-Analysis

BACKGROUND

The role of miR-200c in gastric cancer remains controversial. This study is aimed at clarifying the diagnostic and prognostic value of miR-200c in gastric cancer through a meta-analysis.

METHODS

A comprehensive literature search of PubMed, Embase, and Ovid library databases was conducted. The studies included were those conducted before December 2017. The sensitivity and specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under curve (AUC) were used to estimate the diagnostic value of miR-200c. Meanwhile, the pooled hazard ratio (HR) was used to estimate the prognostic value of miR-200c.

RESULTS

For the diagnostic value of miR-200c, six studies that included 202 patients with gastric cancer and 250 normal controls were analyzed. The sensitivity, specificity, PLR, NLR, DOR, and AUC were 0.74, 0.66, 2.20, 0.40, 5.34, and 0.75, respectively. Subgroup analysis showed no significant difference in the type of the sample, method for testing miR-200c, and ethnicity among the patients. Meanwhile, for the prognostic value of miR-200c, seven studies comprising 935 patients with gastric cancer were analyzed. The pooled results showed that miR-200c expression was associated with overall survival (HR = 2.19) and disease-free survival (HR = 1.73), but not with progression-free survival (HR = 1.64) in patients with gastric cancer. There was no publication bias across the studies.

CONCLUSIONS

Both serum and tissue miR-200c have moderate diagnostic accuracy in gastric cancer. miR-200c could also be used as a valuable indicator for predicting the prognosis of gastric cancer patients.

CircRNA circ_0000190 inhibits the progression of multiple myeloma through modulating miR-767-5p/MAPK4 pathway

Background

Multiple myeloma (MM) accounts for 10% of all hematological malignancies. Dysregulation of microRNAs (miRNAs) or long non-coding RNAs (lncRNAs) has important impacts on progression of MM. Circular RNAs (circRNAs) are correlated with malignancy in the modulation of tumor progression. This study aims to investigate the effect of circ_0000190 on regulating the progression of MM.

Method

Microscopic examination via single molecule fluorescent in situ hybridization indicates the location of circ_0000190. qRT-PCR and Western blot were used to evaluate the expression of RNAs and proteins. Potential target of circ_0000190 was searched as miRNA, and examined by luciferase reporter assay. A computational screen was also conducted to search the potential target of miRNA. In vitro cell viability, proliferation, apoptosis assays and flow cytometric were performed to assess the effects of circ_0000190 and its target on MM. Mice model of human MM was established with subcutaneous xenograft tumor, qRT-PCR and western blot were performed to detect the underlying mechanisms of circ_0000190 on MM.

Results

Circ_0000190 was located in the cytoplasm, and down-regulated in both bone marrow tissue and peripheral blood, while the target of circ_0000190, miR-767-5p, was up-regulated, suggesting a negative correlation between them. The binding ability between circ_0000190 and miR-767-5p was confirmed by luciferase reporter assay. Moreover, circ_0000190 inhibited cell viability, proliferation and induced apoptosis of MM thus inhibiting cell progression, which is partially through the negative regulation of miR-767-5p. Mitogen-activated protein kinase 4 (MAPK4) is a direct target of miR-767-5p. In addition, over-expression of miR-767-5p promoted cell progression by directly targeting and regulating MAPK4. The MM model mice with administration of circ_0000190 suppressed tumor growth and progression.

Conclusion

Our results revealed that the ability of circ_0000190 to protect against MM was inherited through repression of miR-767-5p, and miR-767-5p might be a tumor drive through targeting MAPK4. Therefore, a novel role of circ_0000190 on regulating the progression of MM was found, and the clinical application of circRNAs might represent a strategy in MM.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1071-9) contains supplementary material, which is available to authorized users.

Altered expression of circular RNAs in human placental chorionic plate-derived mesenchymal stem cells pretreated with hypoxia

BACKGROUND

Hypoxic preconditioning alters the biological properties of mesenchymal stem cells (MSCs). It is not known whether this process has an effect on circular RNAs (circRNAs) in MSCs.

METHODS

Human placental chorionic plate-derived MSCs (hpcpMSCs) isolated from the same placentae were classed into two groups: hypoxic pretreated (hypoxia) group and normally cultured (normoxia) group. The comparative circRNA microarray analysis was used to determine circRNAs expression and verified by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) in the two groups.

RESULTS

One hundred and two differentially expressed circRNAs in the hypoxia group were found compared to that in the normoxia group (fold change >1.5-fold and P < 0.05). The expression levels of circRNAs by qRT-PCR were consistent with those evaluated by microarray analysis. Gene ontology (GO) analysis showed that the putative function of their target genes for those differentially expressed circRNAs was primarily involved in cell development and its differentiation and regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that transcriptional misregulation in cancer and mitogen-activated protein kinase (MAPK) signaling pathway were the most significant. MAPK signaling pathway was found to be the core regulatory pathway triggered by hypoxia.

CONCLUSIONS

The results indicate that the altered expression of specific circRNAs in MSCs is associated with hypoxic preconditioning. This finding provides further exploration of underlying mechanisms of the characteristic changes of MSCs with hypoxic preconditioning.

miR-186 promotes tumor growth in cutaneous squamous cell carcinoma by inhibiting apoptotic protease activating factor-1

Cutaneous squamous cell carcinoma (cSCC) accounts for 20% of non-melanoma skin cancer worldwide. MicroRNAs (miRNAs or miRs) are a subtype of non-coding RNA associated with the progression of various types of human cancer. MiR-186 has been demonstrated to act as an oncogene in human tumors. However, the role of miR-186 in cSCC remains unclear. The expression of miR-186 and apoptotic protease activating factor 1 (APAF1) was examined using reverse transcription-quantitative polymerase chain reaction, western blotting and immunofluorescence. The correlation between miR-186 and APAF1 was determined using a dual-luciferase assay. Mimics or inhibitors of miR-186 were transfected into A-431 cells to establish cell lines with overexpressed or knocked-down miR-186, respectively. EdU staining and colony formation assays were performed to detect cell proliferation. Transwell and wound-healing assays were performed to analyze cell invasion and migration, respectively. Hoechst staining and flow cytometry were performed to assess cell apoptosis and cell cycle distribution. MiR-186 expression was significantly increased, while APAF1 expression was significantly decreased in cSCC tissues compared with the controls. An miR-186 binding site was predicted in APAF1 and their expression was negatively correlated in cSCC tissues. Cell proliferation, invasion and migration were significantly enhanced in the miR-186-overexpressed A-431 cells and attenuated in miR-186 knockdown cells compared with the control. APAF1 expression was regulated by miR-186, while APAF1 knockdown significantly promoted cell invasion and inhibited cell apoptosis. In summary, the results of the present study indicate that miR-186 serves as an oncogene in cSCC by inhibiting APAF1.

[Circular RNA in Lung Cancer Research: Biogenesis, Functions and Roles]

肺癌（lung cancer）的发病率及死亡率在我国双居首位，近年来针对肿瘤驱动基因和免疫检查点的靶点治疗取得了振奋人心的成果。环状RNA（circular RNA, circRNA）是一类具有环形结构的RNA分子，研究发现其与肿瘤的分期、淋巴结转移等关系密切，在生理过程和疾病中具有特殊的生物学功能。其高度稳定性和特异性使之有望成为肿瘤潜在的预测和治疗靶点。目前环状RNA在肺癌中的生物学功能和调控机制仅有少量研究报道。本文对环状RNA的研究历史、生源机制、生物学功能以及其在肿瘤，尤其是肺癌研究中的进展作一综述，以期为环状RNA在肺癌中的研究提供理论依据和新的思路。

Hsa_circ_0033155: A potential novel biomarker for non-small cell lung cancer

Circular RNAs (circRNAs) are a novel type of endogenous RNAs and increasing evidence have uncovered the important role of circRNA in tumor progression; however, the function of circRNAs in non-small cell lung cancer (NSCLC) remains largely unclear. In the present study, it was demonstrated that the expression level of hsa_circ_0033155 was significantly downregulated in NSCLC tissue and the expression of hsa_circ_0033155 correlated with lymphatic metastasis. In order to further investigate the possible role of hsa_circ_0033155 in NSCLC progression, circRNA was overexpressed in NSCLC cells and it was observed that the overexpression of hsa_circ_0033155 significantly decreased cell proliferation, colony formation and migration, and elevated the level of phosphatase and tensin homolog deleted on chromosome 10, a tumor suppressor in many types of tumor. In conclusion, hsa_circ_0033155 may serve as a prospective biomarker for detection and a promising therapeutic target for NSCLC.

Overexpressed CDR1as functions as an oncogene to promote the tumor progression via miR-7 in non-small-cell lung cancer

Background

Circular RNA (circRNA) is a novel member of the noncoding RNA and function as efficient microRNA sponges with gene-regulatory potential, especially the circular RNA ciRS-7 (CDR1as)/tumor suppressor miRNA-7 (miR-7) signals. However, the function of CDR1as/miR-7 in non-small cell lung cancer (NSCLC) is unknown.

Methods

Normal lung tissues (n=20), adjacent non-tumor tissues (n=60), and NSCLC tissues (n=60) were collected to determine the expression and significance of CDR1as/miR-7. Lung cancer cell lines A549 and H460 were overexpressed or knocked down of CDR1as, miR-7 to determine the tumor growth etc. The CDR1as/miR-7-related pathway were analyzed.

Results

CDR1as levels was robustly increased with the development of NSCLC (P<0.001) and the NSCLC tissues harbored highest expression of CDR1as, which negatively correlated to the expression of miR-7. Patients with high expression of CDR1as had high TNM stage (P=0.004), more lymph nodes metastasis (LNM) (P=0.021) and shorted overall survival time (OS) (P=0.0135). The CDR1as level was an independent prognostic factor for the patients with NSCLC. Overexpression of CDR1as induced increased cell vitalities and growth, which could be abrogated by knockdown of CDR1as or overexpressed miR-7 to induce apoptosis and G1/S arrest. Mechanistically, CDR1as functioned as miR-7 sponges to up-regulate the key target genes of miR-7 including EGFR, CCNE1 and PIK3CD. The results in vivo further confirmed that CDR1as functioned as oncogene to inhibit the anti-tumor effects of tumor suppressor miR-7 by up-regulation of proliferation index Ki-67, EGFR, CCNE1 and PIK3CD levels.

Conclusion

Overexpressed CDR1as in NSCLC functions promotes the tumor progression via miR-7 signals.

Circulating miRNAs in blood and urine as diagnostic and prognostic biomarkers for bladder cancer: an update in 2017

This study presents a critical appraisal of previously published study data of miRNAs in blood, urine and exosomes as biomarkers of bladder cancer (BC). The evaluation included 39 articles published from the beginning of 2010 until September 2017 and searched in PubMed. The heterogeneity of studies, due to their clinicopathological variability, including insufficient consideration of diagnostic and prognostic biomarker guidelines and missing internal and external validation of data, do not currently allow the recommending of a useful miRNA marker as diagnostic or prognostic tool in BC. Future multi-institutional studies are necessary to overcome the deficiencies in these studies in order to prove the usefulness of circulating miRNAs as robust biomarkers for BC.

Upregulation of circ_0066444 promotes the proliferation, invasion, and migration of gastric cancer cells

BACKGROUND

Circular RNAs (circRNAs), which have closed-loop structure, are involved in the pathogenesis of human diseases including various types of carcinomas. The present study aimed to investigate the relationship between a new circular RNA named circ_0066444 and gastric cancer (GC) carcinogenesis.

MATERIALS AND METHODS

The circ_0066444 levels in 106 paired gastric carcinoma tissues and related adjacent normal tissues were detected by real-time quantitative reverse-transcription polymerase chain reaction. The correlation between the expression of circ_0066444 and clinicopathological features was analyzed. The impact of circ_0066444 expression on cell proliferation, invasion, as well as migration was evaluated in vitro using knockdown expression strategies. Finally, a network of circ_0066444-targeted miRNA interactions and their corresponding mRNAs was constructed.

RESULTS

circ_0066444 was found to be significantly upregulated in 106 GC tissues as compared with paired adjacent nontumorous tissues (P=0.025), showing a high positive correlation with lymphatic metastasis (P=0.023). Furthermore, in vitro assays of the GC cell lines BGC-823 and AGS demonstrated that knockdown of circ_0066444 reduced cell proliferation, invasion, and migration significantly. Prediction and annotation revealed circ_0066444 was able to sponge to 5 miRNAs and 15 corresponding target mRNAs.

CONCLUSION

Our study indicated upregulation of circ_0066444 promotes gastric cell proliferation, invasion, and migration ability and might serve as a novel biomarker for GC.

miRNA regulation of innate immunity

MicroRNAs (miRNAs) are small noncoding RNA and are pivotal posttranscriptional regulators of both innate and adaptive immunity. They act by regulating the expression of multiple immune genes, thus, are the important elements to the complex immune regulatory network. Deregulated expression of specific miRNAs can lead to potential autoimmunity, immune tolerance, hyper-inflammatory phenotype, and cancer initiation and progression. In this review, we discuss the contributory pathways and mechanisms by which several miRNAs influence the development of innate immunity and fine-tune immune response. Moreover, we discuss the consequence of deregulated miRNAs and their pathogenic implications.