CircPCMTD1 Acts as the Sponge of miR-224-5p to Promote Glioma Progression

The importance of the circRNA/Wnt axis in gliomas: Biological functions and clinical opportunities

Gliomas are among the most common cancers in the central nervous system, arising through various signaling pathways. One significant pathway is Wnt signaling, a tightly regulated process that plays a crucial role in gliomagenesis and development. The current study aims to explore the relationship between circular RNAs (circRNAs) and the Wnt/β-catenin signaling pathway in gliomas, considering the growing recognition of circRNAs in disease pathogenesis. A comprehensive review of recent research was conducted to investigate the roles of circRNAs in gliomas, focusing on their expression patterns and interactions with the Wnt signaling pathway. The analysis included studies examining circRNAs' function as microRNA sponges and their impact on glioma biology. The findings reveal that circRNAs are differentially expressed in gliomas and significantly influence the occurrence, growth, and metastasis of these tumors. Specifically, circRNAs interact with the Wnt signaling pathway, affecting glioma development and progression. This interaction highlights the importance of circRNAs in glioma pathophysiology. Understanding the regulatory network involving circRNAs and Wnt signaling offers valuable insights into glioma pathophysiology. CircRNAs hold promise as diagnostic and prognostic biomarkers and may serve as targets for novel therapeutic strategies in glioma treatment.

CircPMS1 promotes proliferation of pulmonary artery smooth muscle cells, pulmonary microvascular endothelial cells, and pericytes under hypoxia

BACKGROUND

Circular RNAs (circRNAs) have been recognized as significant regulators of pulmonary hypertension (PH); however, the differential expression and function of circRNAs in different vascular cells under hypoxia remain unknown. Here, we identified co-differentially expressed circRNAs and determined their putative roles in the proliferation of pulmonary artery smooth muscle cells (PASMCs), pulmonary microvascular endothelial cells (PMECs), and pericytes (PCs) under hypoxia.

METHODS

Whole transcriptome sequencing was performed to analyze the differential expression of circRNAs in three different vascular cell types. Bioinformatic analysis was used to predict their putative biological function. Quantitative real-time polymerase chain reaction, Cell Counting Kit-8, and EdU Cell Proliferation assays were carried out to determine the role of circular postmeiotic segregation 1 (circPMS1) as well as its potential sponge mechanism in PASMCs, PMECs, and PCs.

RESULTS

PASMCs, PMECs, and PCs exhibited 16, 99, and 31 differentially expressed circRNAs under hypoxia, respectively. CircPMS1 was upregulated in PASMCs, PMECs, and PCs under hypoxia and enhanced the proliferation of vascular cells. CircPMS1 may upregulate DEP domain containing 1 (DEPDC1) and RNA polymerase II subunit D expression by targeting microRNA-432-5p (miR-432-5p) in PASMCs, upregulate MAX interactor 1 (MXI1) expression by targeting miR-433-3p in PMECs, and upregulate zinc finger AN1-type containing 5 (ZFAND5) expression by targeting miR-3613-5p in PCs.

CONCLUSIONS

Our results suggest that circPMS1 promotes cell proliferation through the miR-432-5p/DEPDC1 or miR-432-5p/POL2D axis in PASMCs, through the miR-433-3p/MXI1 axis in PMECs, and through the miR-3613-5p/ZFAND5 axis in PCs, which provides putative targets for the early diagnosis and treatment of PH.

Engineered smart materials for RNA based molecular therapy to treat Glioblastoma

Glioblastoma (GBM) is an aggressive malignancy of the central nervous system (CNS) that remains incurable despite the multitude of improvements in cancer therapeutics. The conventional chemo and radiotherapy post-surgery have only been able to improve the prognosis slightly; however, the development of resistance and/or tumor recurrence is almost inevitable. There is a pressing need for adjuvant molecular therapies that can successfully and efficiently block tumor progression. During the last few decades, non-coding RNAs (ncRNAs) have emerged as key players in regulating various hallmarks of cancer including that of GBM. The levels of many ncRNAs are dysregulated in cancer, and ectopic modulation of their levels by delivering antagonists or overexpression constructs could serve as an attractive option for cancer therapy. The therapeutic potential of several types of ncRNAs, including miRNAs, lncRNAs, and circRNAs, has been validated in both in vitro and in vivo models of GBM. However, the delivery of these RNA-based therapeutics is highly challenging, especially to the tumors of the brain as the blood-brain barrier (BBB) poses as a major obstacle, among others. Also, since RNA is extremely fragile in nature, careful considerations must be met while designing a delivery agent. In this review we have shed light on how ncRNA therapy can overcome the limitations of its predecessor conventional therapy with an emphasis on smart nanomaterials that can aide in the safe and targeted delivery of nucleic acids to treat GBM. Additionally, critical gaps that currently exist for successful transition from viral to non-viral vector delivery systems have been identified. Finally, we have provided a perspective on the future directions, potential pathways, and target areas for achieving rapid clinical translation of, RNA-based macromolecular therapy to advance the effective treatment of GBM and other related diseases.

Physiological and pathological functions of circular RNAs in the nervous system

Circular RNAs (circRNAs) are a class of covalently closed single-stranded RNAs that are expressed during the development of specific cells and tissues. CircRNAs play crucial roles in physiological and pathological processes by sponging microRNAs, modulating gene transcription, controlling the activity of certain RNA-binding proteins, and producing functional peptides. A key focus of research at present is the functionality of circRNAs in the nervous system and several advances have emerged over the last 2 years. However, the precise role of circRNAs in the nervous system has yet to be comprehensively reviewed. In this review, we first summarize the recently described roles of circRNAs in brain development, maturity, and aging. Then, we focus on the involvement of circRNAs in various diseases of the central nervous system, such as brain cancer, chronic neurodegenerative diseases, acute injuries of the nervous system, and neuropathic pain. A better understanding of the functionality of circRNAs will help us to develop potential diagnostic, prognostic, and therapeutic strategies to treat diseases of the nervous system.

Circular RNA expression profile identifies potential circulating biomarkers for keratoconus

Early diagnosis is important for improving the outcomes of keratoconus (KC). Stable expression and a closed-loop structure of circular RNAs (circRNAs) make them ideal for the diagnosis and treatment of diseases. However, the expression pattern and potential function of circRNAs in KC is not studied yet. Hence, this study explored the circRNA expression profile of KC corneas through transcriptome sequencing and circRNA expression profile analysis. The diagnostic potential of blood circRNAs for KC was explored by analysing the circRNAs' expression levels of fifty paired blood samples from patients with KC and normal controls. The results showed that 107 significantly upregulated and 145 significantly downregulated circRNAs (|fold change| ≥ 2.0, p-value <0.05) were identified in KC tissues. Eight top differently expressed circRNAs were further validated in more cornea samples. Among them, five circRNAs expressed in peripheral blood, and four circRNAs (circ_0006156, circ_0006117, circ_0000284 and circ_0001801) showed significant downregulation in KC patients' peripheral blood too. The blood circ_0000284 expression levels of early, moderate, and advanced KC patients both were significantly lower than the controls. The blood circ_0006117 expression levels present a positive correlation with corrected distance visual acuity values, and a negative correlation with back elevation values of KC eyes. Notably, the expression levels of these circRNAs distinguished KC patients from their healthy counterparts, with the area under the curve (AUC) of circ_0000284, circ_0001801, and circ_0006117 being 0.7306, 0.6871 and 0.6701, respectively. Further, the AUC value for five circRNAs under the logistic regression model was 0.8203, indicating that they can function as effective biomarkers for the KC diagnostics. In conclusion, the expression of circRNAs showed a relationship with KC, with four significantly differentially expressed circRNAs demonstrating potential as biomarkers for the disease.

The potential role and mechanism of circRNAs in foam cell formation

Atherosclerosis is a significant risk factor for coronary heart disease (CHD) and myocardial infarction (MI). Atherosclerosis develops during foam cell generation, which is caused by an imbalance in cholesterol uptake, esterification, and efflux. LOX-1, SR-A1, and CD36 all increased cholesterol uptake. ACAT1 and ACAT2 promote free cholesterol (FC) esterification to cholesteryl esters (CE). The hydrolysis of CE to FC was aided by nCEH. FC efflux was promoted by ABCA1, ABCG1, ADAM10, and apoA-I. SR-BI promotes not only cholesterol uptake but also FC efflux. Circular RNAs (circRNAs), which are single-stranded RNAs with a closed covalent circular structure, have emerged as promising biomarkers and therapeutic targets for atherosclerosis due to their highly tissue, cell, and disease state-specific expression profiles. Numerous studies have shown that circRNAs regulate foam cell formation, acting as miRNA sponges to influence atherosclerosis development by regulating the expression of SR-A1, CD36, ACAT2, ABCA1, ABCG1, ADAM10, apoA-I, SR-B1. Several circRNAs, including circ-Wdr91, circ 0004104, circRNA0044073, circRNA_0001805, circDENND1B, circRSF1, circ 0001445, and circRNA 102682, are potential biomarkers for atherosclerosis to better evaluate cardiovascular risk. It is difficult to deliver synthetic therapeutic circRNAs to the desired target tissues. Nanotechnology, such as GA-RM/GZ/PL, may be an important solution to this problem. In this review, we focus on the potential role and mechanism of circRNA/miRNA axis in foam cell formation in the hopes of discovering new targets for the diagnosis, prevention, and treatment of atherosclerosis.

Mining glycosylation-related prognostic lncRNAs and constructing a prognostic model for overall survival prediction in glioma: A study based on bioinformatics analysis

Dysregulation of protein glycosylation plays a crucial role in the development of glioma. Long noncoding RNA (lncRNAs), functional RNA molecules without protein-coding ability, regulate gene expression and participate in malignant glioma progression. However, it remains unclear how lncRNAs are involved in glycosylation glioma malignancy. Identification of prognostic glycosylation-related lncRNAs in gliomas is necessary. We collected RNA-seq data and clinicopathological information of glioma patients from the cancer genome atlas and Chinese glioma genome atlas. We used the "limma" package to explore glycosylation-related gene and screened related lncRNAs from abnormally glycosylated genes. Using univariate Cox analyses Regression and least absolute shrinkage and selection operator analyses, we constructed a risk signature with 7 glycosylation-related lncRNAs. Based on the median risk score (RS), patients with gliomas were divided into low- and high-risk subgroups with different overall survival rates. Univariate and multivariate Cox analyses regression analyses were performed to assess the independent prognostic ability of the RS. Twenty glycosylation-related lncRNAs were identified by univariate Cox regression analyses. Two glioma subgroups were identified using consistent protein clustering, with the prognosis of the former being better than that of the latter. Least absolute shrinkage and selection operator analysis identified 7 survival RSs for glycosylation-related lncRNAs, which were identified as independent prognostic markers and predictors of glioma clinicopathological features. Glycosylation-related lncRNAs play an important role in the malignant development of gliomas and may help guide treatment options.

Diagnostic and therapeutic potential of circular RNA in brain tumors

Circular RNAs (circRNAs) are a class of RNA with a stable cyclic structure. They are expressed in various tissues and cells with conserved, specific characteristics. CircRNAs have been found to play critical roles in a wide range of cellular processes by regulating gene expression at the epigenetic, transcriptional, and posttranscriptional levels. There is an accumulation of evidence on newly discovered circRNAs, their molecular interactions, and their roles in the development and progression of human brain tumors, including cell proliferation, cell apoptosis, invasion, and chemoresistance. Here we summarize the current state of knowledge of the circRNAs that have been implicated in brain tumor pathogenesis, particularly in gliomas and medulloblastomas. In providing a comprehensive overview of circRNA studies, we highlight how different circRNAs have oncogenic or tumor-suppressive roles in brain tumors, making them attractive therapeutic targets and biomarkers for personalized therapy and precision diagnostics. This review article discusses circRNAs' functional roles and the prospect of using them as diagnostic biomarkers and therapeutic targets in patients with brain tumors.

The roles and mechanisms of circular RNAs related to mTOR in cancers

BACKGROUND

Circular RNAs (circRNAs) are stable molecules with covalently closed structures that have an irreplaceable role in the occurrence, progression, and even treatment of plenty of cancers. Mammalian/mechanistic target of rapamycin (mTOR) is a key regulator in cancers and plays several biological functions, such as proliferation, migration, invasion, autophagy, and apoptosis.

METHODS

All data were collected through PubMed and CNKI, using terms including "circRNA," "mTOR," "caner," "signaling pathway," "biomarker," "diagnosis," "treatment." Articles published in Chinese and English were included.

RESULTS

In this review, the expression, function, and mechanism of circRNA-associated mTOR in cancers were described. CircRNA-associated-mTOR can regulate the progression and therapy of a variety of cancers in multiple signaling pathways, such as phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mTOR, mitogen-activated protein kinase (MAPK)/mTOR, and AMP-activated protein kinase (AMPK)/mTOR axis. These cancers including esophageal carcinoma (circLPAR3, ciRS-7), gastric cancer (circNRIP1, hsa_circ_0010882, hsa_circ_0000117, hsa_circ_0072309, and circST3GAL6), colorectal cancer (hsa_circ_0000392, hsa_circ_0084927, hsa_circ_0104631, and circFBXW7), liver cancer (circC16orf62, hsa_circ_100338, hsa_circ_0004001, hsa_circ_0004123, hsa_circ_0075792, hsa_circ_0079299, and hsa_circ_0002130), pancreatic cancer (circ-IARS and circRHOBTB3), renal carcinoma (ciRS-7), bladder cancer (circUBE2K), prostate cancer (circMBOAT2 and circ-ITCH), ovarian cancer (circEEF2, circRAB11FIP1, circMYLK, and circTPCN), endometrial cancer (hsa_circ_0002577 and circWHSC1), lung cancer (circHIPK3, hsa_circ_0001666), thyroid cancer (hsa_circ_0007694 and hsa_circ_0008274), glioma (circGFRA1, circ-MAPK4, circPCMTD1, and hsa_circ_0037251), osteosarcoma (circTCF25), leukemia (circ-PRKDC), and breast cancer (hsa_circ_0000199, circUBAP2, and circWHSC1).

Beyond the Code: Noncoding RNAs in Skin Wound Healing

An increasing number of noncoding RNAs (ncRNAs) have been found to regulate gene expression and protein functions, playing important roles in diverse biological processes and diseases. Their crucial functions have been reported in almost every cell type and all stages of skin wound healing. Evidence of their pathogenetic roles in common wound complications, such as chronic nonhealing wounds and excessive scarring, is also accumulating. Given their unique expression and functional properties, ncRNAs are promising therapeutic and diagnostic entities. In this review, we discuss current knowledge about the functional roles of noncoding elements, such as microRNAs, long ncRNAs, and circular RNAs, in skin wound healing, focusing on in vivo evidence from studies of human wound samples and animal wound models. Finally, we provide a perspective on the outlook of ncRNA-based therapeutics in wound care.

E2F1-induced microRNA-224-5p expression is associated with hepatocellular carcinoma cell migration, invasion and epithelial-mesenchymal transition via MREG

MicroRNA (miR)-224-5p has been reported to be associated with multiple types of cancer. However, its biological role and underlying mechanism in hepatocellular carcinoma (HCC) has yet to be fully elucidated. The aim of the present study was to investigate whether miR-224-5p mRNA expression level was increased in hepatocellular carcinoma and whether it was associated with poor prognosis. Decreased mRNA expression level of miR-224-5p was shown to suppress liver cancer cell migration, invasion and epithelial-mesenchymal transition (EMT). Mechanistically, E2F1 was found to regulate miR-224-5p expression by binding to its promoter region. Melanoregulin (MREG) was identified as the direct target of miR-224-5p by searching the TargetScan, miRDB and StarBase databases. Overexpression of MREG could attenuate liver cancer cell migration, invasion and EMT. Rescue experiments further confirmed that MREG was associated with the regulation of miR-224-5p in liver cancer. In addition, the E2F1/miR-224-5p axis was shown to promote liver cancer cell migration, invasion and EMT by regulating MREG expression. These results suggested that E2F1-induced upregulation of miR-224-5p may serve an important role in MREG-induced liver cancer cell migration, invasion and EMT, and highlights the regulatory function of miR-224-5p in liver cancer. Therefore, the E2F1/miR-224-5p/MREG axis may provide a theoretical basis for the clinical treatment of hepatocellular carcinoma.

Circular RNA circFGFR1 Functions as an Oncogene in Glioblastoma Cells through Sponging to hsa-miR-224-5p

Recently, increased studies have shown the important regulatory role of circular RNA (circRNA) in cancer progression and development, including glioblastoma (GBM). However, the function of circRNAs in glioblastoma is still largely unclear. Here, we state that circFGFR1 is elevated in glioma cells, resulting in aggravated glioma aggravated malignancy. The upregulation of circFGFR1 also promotes glioma growth in mouse xenograft models. Furthermore, CXCR4 level in glioma cells is positively correlated with circFGFR1 level, and higher CXCR4 expression is found in circFGFR1 overexpression groups. The effect of circFGFR1 on glioma malignancy is abolished in CXCR4 knockout cells. Then, RIP, RNA pull-down, and luciferase reporter assay results showed that hsa-miR-224-5p directly binds to circFGFR1 and CXCR4 mRNA. The CXCR4 3′-untranslated region (UTR) activated luciferase activity was reduced with hsa-miR-224-5p transfection, while it is reversed when cotransfected with circFGFR1, indicating that circFGFR1 acts as a hsa-miR-244-5p sponge to increase CXCR4 expression. The hsa-miR-224-5p expression is negatively corrected with the glioma malignancy through inhibiting CXCR4 level. Besides, the circFGFR1-induced regulation in glioma malignancy is also abrogated in hsa-miR-224-5p knockout cells. Taken together, our findings suggest that circFGFR1 plays a critical role in the tumorigenic behaviors in glioma cells by upregulating CXCR4 expression via sponging to hsa-miR-224-5p. These findings provide a new perspective on circRNAs during GBM development.

LncRNA LINC01094 contributes to glioma progression by modulating miR-224-5p/CHSY1 axis

Glioma serves as the most common malignancy influencing modern people and is associated with severe morbidity and high mortality. Long non-coding RNAs (lncRNAs) as crucial regulators participate in multiple cancer progression. However, the role of lncRNA LINC01094 in the development of glioma remains unclear. Here, we aimed to explore the effect of lncRNA LINC01094 on the glioma progression and the underlying mechanism. Significantly, we revealed that the expression levels of LINC01094 were elevated in the glioma patient tissues compared to adjacent normal tissues. The LINC01094 expression was enhanced in the glioma cell lines. The depletion of LINC01094 inhibited cell viability and colony formation in the glioma cells. Meanwhile, the migration and invasion of glioma cells were impaired by the depletion of LINC01094. Mechanically, we identified that LINC01094 was able to sponge the miR-224-5p in the glioma cells and miR-224-5p inhibitor could reverse the effect of LINC01094 on glioma progression. In addition, miR-224-5p targeted CHSY1 and LINC01094 up-regulated CHSY1 by targeting miR-224-5p in the glioma cells. LINC01094 promoted glioma progression by the positive regulation of CHSY1. Moreover, tumorigenicity analysis showed that LINC01094 enhanced tumor growth of glioma in vivo. Thus, we conclude that lncRNA LINC01094 promotes glioma progression by modulating miR-224-5p/CHSY1 axis. Our finding provides new insights into the mechanism by which lncRNA LINC01094 contributes to the development of glioma, improving the understanding of lncRNA LINC01094 and glioma. LncRNA LINC01094, miR-224-5p, and CHSY1 may serve as potential targets for glioma.

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.

HPV-Positive and HPV-Negative Vulvar Squamous Cell Carcinoma Are Biologically, but Not Clinically, Distinct

Vulvar squamous cell carcinoma (VSCC) pathogenesis is traditionally defined by the presence or absence of human papillomavirus (HPV), but the definition of these groups and their molecular characteristics remains ambiguous across studies. Here, we present a retrospective cohort analysis of 36 patients with invasive VSCC where HPV status was determined using RNA in situ hybridization (ISH) and polymerase chain reaction (PCR). Clinical annotation, p16 immunohistochemistry (IHC), programmed death ligand-1 (PD-L1) IHC, HPV16 circular E7 RNA (circE7) detection, and RNA-sequencing (RNA-seq) of the cases was performed. A combination of ISH and PCR identified 20 cases (55.6%) as HPV-positive. HPV-status did not impact overall survival (HR: 1.36, 95% CI: 0.307 to 6.037, p=0.6857) or progression-free survival (HR: 1.12, 95% CI: 0.388 to 3.22, p=0.8367), and no significant clinical differences were found between the groups. PD-L1 expression did not correlate with HPV status, but increased expression of PD-L1 correlated with worse overall survival. Transcriptomic analyses (n=23) revealed distinct groups, defined by HPV status, with multiple differentially expressed genes previously implicated in HPV-induced cancers. HPV-positive tumors showed higher global expression of endogenous circular RNAs (circRNAs), including several circRNAs that have previously been implicated in the pathogenesis of other cancers.

Expression of the circular RNAs in astaxanthin promotes cholesterol efflux from THP-1 cells based on RNA-seq

BACKGROUND

It is reported that circular RNAs (circRNAs) play a key role in atherosclerosis (AS). Foam cell formation, which is the main feature of AS, can be significantly inhibited by cholesterol efflux.

METHODS

We established a model of astaxanthin (AST) promoting cholesterol efflux from macrophages through oil red O staining, real-time quantitative PCR (qRT-PCR), and western blot and used RNA sequencing to detect the expression of circRNAs in AST-treated and untreated THP-1 cells. Finally, siRNA transfection screened out circRNAs that were significantly differentially expressed. The data analysis was performed by Student's t test and P < 0.05 was considered statistically significant.

RESULTS

In the model of AST promoting cholesterol efflux from THP-1 cells, there were a total of 7276 circRNAs differentially expressed, among which the top 25 upregulated and the top 25 downregulated circRNAs were selected based on the log2 (fold change). GO analysis showed that differential expression of circRNAs in biological process (2066/3098; 66.69%), molecular function (543/3098; 17.53%), and cellular component (489/3098; 15.78%). Based on KEGG analysis, RNA transport was the most enriched pathway. Finally, we obtained 3 significantly upregulated circRNAs by siRNA transfection and qRT-PCR.

CONCLUSIONS

The 3 differentially expressed circRNAs may play an important role in the process of AST promoting cholesterol efflux and may be used as biomarkers to prevent AS.

MiR-224-5p Targeting OCLN Promotes the Proliferation, Migration, and Invasion of Clear Cell Renal Cell Carcinoma Cells

A number of studies reported that miR-224-5p is involved in a variety of cancer-related cellular processes, yet its physiological role in clear cell renal cell carcinoma (ccRCC) remains unclear. In order to clarify the function of miR-224-5p in ccRCC, real-time quantitative-PCR was conducted to compare the expression of miR-224-5p in human normal renal tubular epithelial cell lines and ccRCC cell lines first, and a strikingly upregulated expression was observed in ccRCC cell lines. Inhibition of miR-224-5p expression by microRNA inhibitors could inhibit the proliferation, migration, and invasion of ccRCC cells. Besides, it was validated by dual-luciferase assay in which miR-224-5p directly targeted OCLN gene. The expression of OCLN was downregulated in ccRCC cells, and overexpression of miR-224-5p could inhibit the mRNA and protein expression levels of OCLN. Overexpression of OCLN could reduce the proliferation, migration, and invasion of ccRCC cells, while overexpressed miR-224-5p could partially reverse that inhibitory effect. Therefore, the promotive effect of miR-224-5p on the proliferation, invasion, and migration of ccRCC cell lines was at least partly due to the inhibition of OCLN expression. These findings highlighted the important function of miR-224-5p, which was promoting cell proliferation, migration, and invasion by downregulating OCLN, in the pathogenesis of ccRCC, and provided a potential treatment strategy.

Extracellular vesicles derived from cancer-associated fibroblast carries miR-224-5p targeting SLC4A4 to promote the proliferation, invasion and migration of colorectal cancer cells

More and more studies indicated that extracellular vesicles (EVs) carrying miRNAs have been potential biomarkers of various cancers including colorectal cancer (CRC). This study aims to explore the function of miR-224-5p carried by EVs derived from cancer-associated fibroblasts (CAFs) in CRC. Here, we found that miR-224-5p was highly expressed while SLC4A4 was lowly expressed in CRC cells. Moreover, dual-luciferase reporter gene assay testified that miR-224-5p targeted SLC4A4. The expression of miR-224-5p in CAFs-derived EVs was found to be elevated. It was also testified that CAFs-derived EVs could transfer miR-224-5p into CRC cells. miR-224-5p in CAFs-derived EVs facilitated the proliferation, migration, invasion and anti-apoptosis of CRC cells. Overexpressing miR-224-5p increased the proliferative, migratory and invasive abilities of CRC cells and inhibit CRC cell apoptosis, while overexpressing SLC4A4 caused the opposite result. Research in vitro and in vivo further indicated that miR-224-5p promoted CRC cell progression via binding to its downstream target gene SLC4A4. Rescue assay also demonstrated that overexpressing miR-224-5p reversed the inhibitory effect of overexpressed SLC4A4 on cancer cell growth. In addition, in vivo assay identified that high level of miR-224-5p promoted the growth of cancer cells in mice in vivo. In conclusion, we explored the effect of miR-224-5p in CRC, which helps for further exploration of new methods for CRC targeted therapy.

Circular RNA: A novel type of biomarker for glioma (Review)

With the rapid development of sequencing technologies, the characteristics and functions of circular RNAs (circRNAs) in different tissues, and their underlying pathophysiological mechanisms, have been identified. circRNAs are significantly enriched in the brain and are continually expressed from the embryonic stage to the adult stage in rats. Previous studies have reported that certain circRNAs are differentially expressed in glioma and regulate a number of biological processes, such as cell proliferation, metastasis and oncogenesis of glioma. Furthermore, certain circRNAs have been associated with tumor size, World Health Organization tumor grade and poor prognosis in patients with glioma. It has been hypothesized that circRNAs may be involved in the onset and progression of glioma through transcriptional regulation, protein translation and binding to microRNAs. These properties and functions suggest the potential of circRNAs as prognostic biomarkers and therapeutic targets for glioma. For the present review, published studies were examined from PubMed, Embase, Cochrane Central and the reference lists of the retrieved articles. The aim of the present review was to summarize the progress of circRNA research in glioma, discuss the potential diagnostic and prognostic values, and the roles of circRNAs in glioma, and provide a novel theoretical basis and research concepts for the prediction, diagnosis and treatment of glioma.

Knockdown of hsa_circ_0134111 alleviates the symptom of osteoarthritis via sponging microRNA-224-5p

The relevance of circular RNAs (circRNAs) has been indicated in the progression of various diseases. Nevertheless, the precise function of circRNAs in osteoarthritis (OA) remains to be established. Therefore, we aimed to investigate changes in the expression of a specific circRNA, hsa_circ_0134111 (circ_PDE1C) and predict its functions in OA. A rat model of OA was constructed to detect circ_PDE1C expression in knee joint tissues. Subsequently, CHON-001 chondrocytes were treated with IL-1β to mimic OA in vitro. circ_PDE1C was significantly overexpressed in knee cartilage tissues from OA patients relative to amputation patients. Knockdown of circ_PDE1C inhibited extracellular matrix (ECM) degradation and chondrocyte apoptosis. Furthermore, circ_PDE1C could target miR-224-5p, and miR-224-5p expressed poorly in knee cartilage tissues from OA patients. Overexpression of miR-224-5p inhibited ECM degradation and apoptosis in chondrocytes. miR-224-5p also targeted CCL2, which activated the JAK2/STAT signaling pathway, thereby promoting cartilage degradation and exacerbating the symptoms of OA patients. In conclusion, our findings underscore a novel role of circ_PDE1C in OA pathogenesis and suggest that targeting circ_PDE1C/miR-224-5p/CCL2 axis might provide an attractive approach for OA therapy.

Competing Endogenous RNA Networks in Glioma

Gliomas are the most common and malignant primary brain tumors. Various hallmarks of glioma, including sustained proliferation, migration, invasion, heterogeneity, radio- and chemo-resistance, contribute to the dismal prognosis of patients with high-grade glioma. Dysregulation of cancer driver genes is a leading cause for these glioma hallmarks. In recent years, a new mechanism of post-transcriptional gene regulation was proposed, i.e., "competing endogenous RNA (ceRNA)." Long non-coding RNAs, circular RNAs, and transcribed pseudogenes act as ceRNAs to regulate the expression of related genes by sponging the shared microRNAs. Moreover, coding RNA can also exert a regulatory role, independent of its protein coding function, through the ceRNA mechanism. In the latest glioma research, various studies have reported that dysregulation of certain ceRNA regulatory networks (ceRNETs) accounts for the abnormal expression of cancer driver genes and the establishment of glioma hallmarks. These achievements open up new avenues to better understand the hidden aspects of gliomas and provide new biomarkers and potential efficient targets for glioma treatment. In this review, we summarize the existing knowledge about the concept and logic of ceRNET and highlight the emerging roles of some recently found ceRNETs in glioma progression.

Circular RNAs in the Central Nervous System

Circular RNAs (circRNAs) are endogenous single-stranded RNAs characterized by covalently closed loop structures with neither 5′ to 3′ polarity nor poly(A) tails. They are generated most commonly from back-splicing of protein-coding exons. CircRNAs have a tissue-specific distribution and are evolutionarily conserved, and many circRNAs play important biological functions by combining with microRNAs and proteins to regulate protein functions and their own translation. Numerous studies have shown that circRNAs are enriched in the central nervous system (CNS) and play an important role in the development and maintenance of homeostasis. Correspondingly, they also play an important role in the occurrence and progression of CNS diseases. In this review, we highlight the current state of circRNA biogenesis, properties, function and the crucial roles they play in the CNS.

LINC00466 Impacts Cell Proliferation, Metastasis and Sensitivity to Temozolomide of Glioma by Sponging miR-137 to Regulate PPP1R14B Expression

Purpose

LINC00466 is a newfound long non-coding RNA (lncRNA) that has been rarely explored in cancers. However, the specific role and molecular mechanism of LINC00466 in glioma remain to be further elucidated.

Methods

Bioinformatic analysis was used to screen differentially expressed genes. Quantitative real-time PCR (qRT-PCR) was used to determine the expression of LINC00466, microRNA-137 (miR-137) and protein phosphatase 1 regulatory subunit 14B (PPP1R14B). Dual-luciferase reporter gene assay and RNA binding protein Immunoprecipitation (RIP) assays were employed to verify the binding relationship among LINC00466, miR-137 and PPP1R14B. The sensitivity of glioma cells to temozolomide (TMZ) was measured by cell counting kit-8 (CCK8) assay. The xenograft nude models were used to test the effects of LINC00466 on glioma tumor growth in vivo.

Results

Highly expressed LINC00466 and PPP1R14B and lowly expressed miR-137 were eventually revealed in glioma tissues. Overexpression of LINC00466 could promote proliferation, metastasis and drug sensitivity to TMZ of glioma cells. LINC00466 could bind to miR-137, and up-regulation of miR-137 could attenuate the enhancing effects caused by LINC00466 overexpression. We took a further step and found that miR-137 could bind to PPP1R14B. Besides, LINC00466 could function as a sponge to miR-137 to regulate PPP1R14B. In addition, overexpression of LINC00466 could promote tumor growth in vivo.

Conclusion

These findings validate LINC00466 could restrain the miR-137 expression to up-regulate PPP1R14B and therefore promote proliferation, metastasis and resistance to TMZ of glioma.

CircRNA PIP5K1A promotes the progression of glioma through upregulation of the TCF12/PI3K/AKT pathway by sponging miR-515-5p

Background

Increasing studies have revealed that circular RNAs (CircRNAs) make great contributions to regulating tumor progression. Therefore, we intended to explore the expression characteristics, function, and related mechanisms of a novel type of circRNA, PIP5K1A, in glioma.

Methods

Firstly, reverse transcription-polymerase chain reaction (RT-PCR) was carried out to examine CircPIP5K1A expression in glioma tissues and adjacent normal tissues, and the correlation between CircPIP5K1A level and the clinical-pathological indicators of glioma was analyzed. Then, the CircPIP5K1A expression in various glioma cell lines was detected, and CircPIP5K1A overexpression and knockdown cell models were constructed. Subsequently, cell proliferation and viability were detected by the CCK8 method and BrdU staining. Cell apoptosis was detected by flow cytometry, and cell invasion was examined by Transwell assay. The expression of TCF12, PI3K/AKT pathway apoptotic related proteins (Caspase3, Bax, and Bcl2) and epithelial-mesenchymal transition (EMT) markers (E-cadherin, Vimentin, and N-cadherin) was determined by western blot or RT-PCR.

Results

The results manifested that CircPIP5K1A was upregulated in glioma tissues (compared with that in normal adjacent tissues), and overexpressed CircPIP5K1A was related to glioma volume and histopathological grade. Functionally, overexpressing CircPIP5K1A notably elevated glioma cell proliferation, invasion, and EMT and inhibited apoptosis both in vivo and in vitro. Besides, CircPIP5K1A upregulated TCF12 and PI3K/AKT activation. Bioinformatics analysis testified that miR-515-5p was a common target of CircPIP5K1A and TCF12, while the dual-luciferase reporter assay and RNA immunoprecipitation (RIP) experiment further confirmed that CircPIP5K1A targeted miR-515-5p, which bound the 3′-untranslated region (UTR) of TCF12.

Conclusions

Overall, the study illustrated that CircPIP5K1A is a potential prognostic marker in glioma and regulates glioma evolvement by modulating the miR-515-5p-mediated TCF12/PI3K/AKT axis.

Circular RNA Signature in Lung Adenocarcinoma: A MiOncoCirc Database-Based Study and Literature Review

Circular RNAs (circRNAs) are a class of endogenous non-coding RNAs (ncRNAs) with a structure of covalently closed continuous loops, which can regulate gene expression by acting as a microRNA sponge or through other mechanisms. Recent studies have identified that the expression of candidate circRNAs are dysregulated in various tumors and hence are considered as promising diagnostic or therapeutic targets across cancer types. However, the expression and function of circRNAs in lung adenocarcinoma (LUAD) remains unclear. In this article, we investigated the expression of circRNAs in LUAD via MiOncoCirc, which is the first and comprehensive database characterizing circRNAs across >2,000 cancer samples using an exome capture RNA sequencing. We identified seven abnormally expressed circRNAs in LUAD, including circCDR1-AS, circHIPK3, circFNDC3B, circPCMTD1, circRHOBTB3, circFAM13B, and circMAN1A2, as well as conducted a literature review about the function and features of these circRNAs. Previous studies have demonstrated that circCDR1-AS, circMAN1A2, and circHIPK3 were upregulated and significantly correlated with a poor survival, or promoted the tumor progression in lung cancer, whereas other circRNAs have not been fully explored. Besides, we reviewed all the publications regarding circRNAs and LUAD, and noticed that the dysregulation of these circRNAs impacts the development of LUAD through a variety of regulatory mechanisms. In conclusion, the underlying mechanisms of aberrant expression and functions of circRNAs in LUAD are worthy of being further investigated.

CircFBXW7 alleviates glioma progression through regulating miR-23a-3p/PTEN axis

Increasing evidence has confirmed that circular RNAs (circRNAs) are involved in regulating the development and progression of various tumors. The aim of this study was to examine the effect of circFBXW7 on the progression of glioma and to determine its underlying mechanism. qRT-PCR was performed to measure the expression of circFBXW7, miR-23a-3p, and PTEN in tissues and cell lines of glioma. The proliferation ability of glioma cells was examined using the CCK-8 assay. Glioma cell migration and invasion capacity were detected using Transwell assays. The dual-luciferase reporter gene assay was employed to examine the correlation between miR-23a-3p and circFBXW7 or PTEN. The expression levels of the related genes were determined using western blotting analysis. A glioma xenograft tumor model was employed to evaluate the functional roles of circFBXW7 in vivo. CircFBXW7 was found to be aberrantly downregulated in glioma tumor tissues and cell lines. Overexpression of circFBXW7 was found to significantly inhibit the proliferation, migration and invasion ability of the glioma cells. Moreover, bioinformatic analysis and dual-luciferase reporter assays confirmed that circFBXW7 can directly target miR-23a-3p, which then blocks the binding of miR-23a-3p to the 3' un-translated region (UTR) of PTEN. Mechanically, circFBXW7 suppresses cell proliferation and metastasis in glioma by sponging miR-23a-3p, resulting in elevated PTEN expression. In addition, in vivo experiments also confirmed that circFBXW7 overexpression effectively halts tumor growth and metastasis. Consistent with the in vitro observations, circFBXW7 overexpression significantly decreased miR-23a-3p, Ki-67, and N-cadherin, as well as increased PTEN and E-cadherin levels. Our results revealed that circFBXW7 exhibits antiproliferative and antimetastasis activities via sponging miR-23a-3p to elevate PTEN expression in glioma, which may offer a novel target for clinical therapy and diagnosis of glioma.

Blocking the LncRNA MALAT1/miR-224-5p/NLRP3 Axis Inhibits the Hippocampal Inflammatory Response in T2DM With OSA

Studies have shown that diabetes can cause cognitive dysfunction, and cognitive dysfunction in patients with diabetes combined with obstructive sleep apnea (OSA) is more severe. LncRNAs are known to be associated with type 2 diabetes mellitus (T2DM) with OSA. This study aimed to investigate the role and underlying mechanism of the lncRNA MALAT1/miR-224-5p/NLRP3 axis in T2DM with OSA. qRT-PCR was used to quantify the expression of MALAT1, miR-224-5p, and NLRP3 in brain tissues. NLRP3 expression was assessed by immunohistochemistry (IHC) and immunofluorescent labeling. The interaction involving MALAT1, miR-224-5p, and NLRP3 was evaluated by transfection. Western blotting was utilized to evaluate the expression levels of the pathway-related proteins NLRP3, caspase 1, tumor necrosis factor-α (TNF-α) and interleukin-1 β (IL-1β) both in vitro and in vivo. qRT-PCR was used to assess the mRNA expression levels of NLRP3, caspase 1, TNF-α and IL-1β both in vitro and in vivo. In brain tissues of T2DM with OSA, MALAT1 and NLRP3 were overexpressed, while miR-224-5p was downregulated, which was consistent with subsequent cell experiments. We screened the miRNAs that could bind to MALAT1 and NLRP3 by the StarBase database and the TargetScanMouse7.2 website. Our research showed that among these miRNAs, the level of miR-224-5p was most significantly negatively correlated with the levels of MALAT1 and NLRP3. Also, a firefly luciferase assay showed that miR-224-5p, which is a target of MALAT1, directly reduced the expression of the downstream protein NLRP3. Overexpression of miR-224-5p significantly inhibited the expression levels of NLRP3, caspase 1, TNF-α and IL-1β in vitro. MALAT1 promoted NLRP3 expression by acting as a competing endogenous RNA and sponging miR-224-5p. MiR-224-5p reduces microglial inflammation activation through the regulation of NLRP3 expression, which ultimately affected the NLRP3/IL-1β pathway in the hippocampus. This suggests that miR-224-5p may serve as a potential target for T2DM and OSA therapy.

MiR-210-3p Inhibits Proliferation and Migration of C6 Cells by Targeting Iscu

Glioma is the most common primary brain tumor and the most malignant type of glioma is glioblastoma with the character of high mortality, high recurrence rate and poor prognosis. MicroRNAs act as an important component in glioma development and thus may be a potential target for the treatment of glioma. There were some researches indicated that miR-210-3p played a role in glioma development, but if it can inhibit glioma growth, as well as the underlying mechanism, is still uncertain. In the present study, we investigated the effects of miR-210-3p and its potential target gene Iscu on glioma (C6) cells proliferation and migration in vitro as well as the influence of miR-210-3p on glioma growth in vivo. The results showed that miR-210-3p inhibited the proliferation and migration of C6 cells by regulating the expression of its target gene Iscu in vitro. We also demonstrated that glioma growth was suppressed in immunodeficient mice when they were implanted with C6 cells overexpressing miR-210-3p. Our data indicated that miR-210-3p played an important role in the prevention of glioma growth by targeting Iscu and so miR-210-3p/Iscu axis might be a potential target for the treatment of glioma.

CircLARP4 Suppresses Cell Proliferation, Invasion and Glycolysis and Promotes Apoptosis in Non-Small Cell Lung Cancer by Targeting miR-135b

Background

CircLARP4 is reported to act as a tumor suppressor in some cancers. However, the detailed roles and molecular basis of circLARP4 in non-small cell lung cancer (NSCLC) tumorigenesis are still unclear. The aim of the study is to explore the potential roles and molecular basis of circLARP4 in NSCLC tumorigenesis.

Materials and Methods

qRT-PCR was taken to detect circLARP4 and miR-135b expressions. MTT assay, transwell invasion assay and flow cytometry analysis were applied to evaluate cell proliferation, invasion and apoptosis, respectively. Glycolysis was assessed by measuring hexokinase2 (HK2) expression, glucose consumption and lactate production. Association between circLARP4 and miR-135a was examined by luciferase reporter and RIP assays. The changes of the phosphatase and tension homolog (PTEN)/protein kinase B (AKT)/hypoxia-inducible factor-1α (HIF-1α) pathway were evaluated by Western blot. The nude mouse xenograft models were applied to verify the regulation of circLARP4 in vivo.

Results

CircLARP4 was decreased in NSCLC tissues and cells. CircLARP4 overexpression blocked cell proliferation and invasion, and facilitated apoptosis in NSCLC cells. Meanwhile, circLARP4 overexpression suppressed glycolysis in NSCLC cells, as evidenced by the reduced HK2, glucose consumption and lactate production levels. Further analyses proved a downregulation of miR-135b by circLARP4 in a ceRNA-dependent manner in NSCLC cells. CircLARP4-mediated tumor suppression on NSCLC progression was partially overturned by overexpressing miR-135b. Moreover, we confirmed that circLARP4 had antitumor effect on xenograft tumors and downregulated miR-135b. Furthermore, circLARP4 overexpression inhibited the PTEN/AKT/HIF-1α pathway in NSCLC cells and xenograft tumors by downregulating miR-135b.

Conclusion

Our findings suggested that circLARP4 suppressed NSCLC progression by sponging miR-135b through inactivation of the PTEN/AKT/HIF-1α pathway, which broadens our understanding concerning the roles of circLARP4 in NSCLC tumorigenesis.

circKIF4A promotes tumorogenesis of glioma by targeting miR-139-3p to activate Wnt5a signaling

Background

Glioma has the characteristics of high incidence and mortality, and is a common malignant tumor of the central nervous system. Circular RNAs (circRNAs) have been reported to play vital roles in progression of cancer including glioma, and circKIF4A is up-regulated in glioma tissues. However, its role and mechanisms in gliomas are unclear.

Methods

circKIF4A and miR-139-3p were determined by qRT-PCR. Transwell assay, wound-healing assay, cell colony formation and flow cytometry were performed to measure cell invasion, migration, proliferation and apoptosis. Western blotting was used to evaluate Wnt/β-catenin pathway-related protein. Luciferase reporter assays confirmed the relationship among circKIF4A, miR-139-3p and Wnt5a. Sphere formation was performed to measure the ability of glioma-initiating cells (GICs) spheroid formation. A nude mouse xenograft model was established and immunohistochemical staining was used to detect Ki-67 and Wnt5a levels.

Results

circKIF4A and Wnt5a were up-regulated and miR-139-3p was down-regulated in both glioma cells and tissues. circKIF4A promoted Wnt5a expression by sponging miR-139-3p. Knockdown of circKIF4A inhibited the colony formation ability, migration and invasion, and promoted the apoptosis of glioma cells by regulating miR-139-3p. Knockdown of circKIF4A inhibited Wnt/β-catenin signaling pathway and proliferation-related signal via miR-139-3p. Furthermore, knockdown of circKIF4A or overexpression of miR-139 suppressed the ability of sphere formation of GICs and inhibitd Wnt/β-catenin signaling pathway and proliferation-related signal in GICs. Additionally, depletion of circKIF4A decreased the expression level of Wnt5a and Ki-67, inhibited tumorigenesis in xenograft modes.

Conclusion

circKIF4A was overexpressed in glioma, and knockdown of circKIF4A suppressed glioma progression via miR-139-3p/Wnt5a axis. The results indicated that circKIF4A may be a potential target for clinical treatment of glioma.

Circular RNA CircHIPK3 Promotes Gemcitabine Sensitivity in Bladder Cancer

Purpose: Recent studies showed circular RNA (circRNA) played important regulatory roles in tumors, including genesis of chemotherapy resistance. In this study, the role of circHIPK3 on chemotherapy resistance of bladder cancer (BC) will be clarified. Methods: Real-time quantitative PCR was applied to examine the circHIPK3 expression. The gemcitabine sensitivity and cell proliferation viability were analyzed by Cell Counting Kit-8 assay. Double-stained flow cytometry was used to detect the cell apoptosis. Results: In BC tissues and cell lines, the circHIPK3 expression was down-regulated. Its expression had a negative correlation with pathological grade, lymph node metastasis and gemcitabine insensitivity of BC patients. CircHIPK3 was a independent prognostic biomarker for BC patients. The expression of circHIPK3 in T24/gem and J82/gem cell lines (resistant to gemcitabine) was down-regulated significantly. The over-expression of circHIPK3 decreased IC50 of gemcitabine and promoted gemcitabine's cytotoxicity in T24/gem and J82/gem cells. Conclusions: The circHIPK3 is low-expressed in BC and is an independent prognostic biomarker for BC patients. The low-expression of circHIPK3 is associated with the insensitivity to gemcitabine of BC patients, over-expression of circHIPK3 promotes gemcitabine sensitivity in BC.

Circular RNA CDR1-AS contributes to pemetrexed and cisplatin chemoresistance through EGFR/PI3K signaling pathway in lung adenocarcinoma

Recent studies found circRNAs were involved in tumorigenesis and became new tumor biomarkers and therapeutic targets in lung adenocarcinoma (LUAD), which played a critical role in various biological processes and had been implicated in resistance to chemotherapeutic drugs. However, the role of CDR1-AS in chemoresistance of LUAD to pemetrexed (PTX) and cisplatin (CDDP) is poorly understood. Here, we found that CDR1-AS was up-regulated in LUAD tissues and cell lines, its high-expression was relevant to smoking history, T stage and neoadjuvant chemotherapy (PTX and CDDP) of LUAD patients. CDR1-AS was an independent prognostic biomarker for LUAD patients. CDR1-AS was highly expressed in PTX and CDDP resistant LUAD tissues and cell line (A549/CR). Silence of CDR1-AS re-sensitized A549/CR cells to PTX and CDDP. CDR1-AS was closely related with EGFR/PI3K signaling pathway in A549/CR cells. The activating of EGFR/PI3K pathway mostly restored the effecting of CDR1-AS silence on PTX and CDDP sensitivity in A549/CR cells, CDR1-AS contributed to PTX and CDDP chemoresistance through EGFR/PI3K signaling pathway in LUAD. In conclusion, the CDR1-AS is high-expressed in LUAD and is an independent prognostic biomarker for LUAD patients. The high-expression of CDR1-AS is related with the PTX and CDDP insensitivity of LUAD patients, CDR1-AS promotes PTX and CDDP chemoresistance through EGFR/PI3K signaling pathway in LUAD.

CircZNF609/miR-134-5p/BTG-2 axis regulates proliferation and migration of glioma cell

Objectives

MicroRNAs are abundant in eukaryotic cells and play key roles in cancers. Circular RNAs (CircRNAs) served as the competing endogenous RNAs (ceRNAs) in mediating multiple cell processes. This study aims to define the role of CircRNA CircZNF609/miR-134-5p in glioma as well as the underlying regulating mechanism.

Methods

Relative expression of miR-134-5p, CircZNF609 and BTG-2 mRNA was determined by quantitative real-time PCR. Cell proliferation was analysed by CCK-8 assay. Cell migration was assessed by cell wound scratch assay. The direct regulatory of miR-134-5p on BTG-2 and CircZNF609 was verified by luciferase report gene assay.

Key findings

MiR-134-5p was significantly upregulated in glioma cells. The overexpression of miR-134-5p inhibited cell proliferation and migration of glioma cell U251 and U87. Reversely, knock-down of miR-134-5p enhanced cell proliferation and migration. Both BTG-2 and CircZNF609 are the direct targets of miR-134-5p, and their expression could be negatively regulated by miR-134-5p. CircZNF609 was significantly upregulated in U251 and U87 cells and acted as an oncogene to promote cell proliferation and cell migration of glioma cell U251 and U87.

Conclusions

These data proved that CircZNF609 served as a competing RNA to bind miR-134-5p that promoted BTG-2 expression leading to reduced proliferation and migration of glioma cell.

Circular RNA USP1 regulates the permeability of blood-tumour barrier via miR-194-5p/FLI1 axis

Recent studies indicate circular RNAs are related to dysregulation of vascular endothelial cell function, yet the underlying mechanisms have remained elusive. Here, we characterized the functional role of circular RNA USP1 (circ‐USP1) in the regulation of the blood‐tumour barrier (BTB) permeability and the potential mechanisms. In the current study, the circ‐USP1 expressing level was up‐regulated in glioma cerebral microvascular endothelial cells (GECs) of the BTB model in vitro. Knockdown of circ‐USP1 disrupted the barrier integrity, increased its permeability as well as reduced tight junction‐related protein claudin‐5, occludin and ZO‐1 expressions in GECs. Bioinformatic prediction and luciferase assay indicated that circ‐USP1 bound to miR‐194‐5p and suppressed its activity. MiR‐194‐5p contributed to circ‐USP1 knockdown‐induced increase of BTB permeability via targeting and down‐regulating transcription factor FLI1. Furthermore, FLI1 regulated the expressions of claudin‐5, occludin and ZO‐1 in GECs through binding to their promoter regions. Single or combined treatment of circ‐USP1 and miR‐194‐5p effectively promoted anti‐tumour drug doxorubicin across BTB to induce apoptosis of glioma cells. Overall, this present study identified the crucial regulation of circ‐USP1 on BTB permeability via miR‐194‐5p/FLI1 axis‐mediated regulation of tight junction proteins, which might facilitate the development of therapeutics against human gliomas.