Circ_0006168 Promotes the Migration, Invasion and Proliferation of Esophageal Squamous Cell Carcinoma Cells via miR-516b-5p-Dependent Regulation of XBP1

N6-methyladenosine-modified circ_0006168 promotes epithelial mesenchymal transition via miR-384/STAT3/Snail axis in esophageal squamous cell carcinoma

Circular RNAs (circRNAs) are involved in the pathogenesis of esophageal squamous cell carcinoma (ESCC). This study aimed to explore the mechanisms of aberrant expression and functions of circ_0006168 in ESCC. In this study, real-time qPCR and fluorescence in situ hybridization (FISH) are adopted to estimate the expression and localization of circ_0006168 in cancer tissues and cells. Methylated RNA immunoprecipitation (MeRIP) was performed to detect the N6-methyladenosine (m6A) modification of circ_0006168. Gain- and loss-of-functions of circ_0006168 were performed to identify its role in ESCC progression. RNA-binding protein immunoprecipitation (RIP) was used to detect the interaction of circ_0006168 with IGF2BP2. Luciferase reporter assay and RIP are used to confirm the circ_0006168/miR-384/STAT3 ceRNA network. Our results showed that the expression of circ_0006168 was upregulated in ESCC tissues and cells. METTL3-mediated m6A modification increased the expression of circ_0006168 via IGF2BP2-dependent way in TE-1 cells. Circ_0006168 promoted cell proliferation, migration, invasion, cell cycle progression and inhibited cell apoptosis, while knockdown of circ_0006168 had the reverse effects. Mechanistically, circ_0006168 acted its functions via miR-384/STAT3/Snail axis in TE-1 cells. In conclusion, circ_0006168 is upregulated in ESCC and m6A methylation increased its expression via IGF2BP2. CircRNA_0006168 promotes cell migration, invasion by regulating EMT via miR-384/STAT3/Snail axis in ESCC.

Exosomal circCNOT6L Regulates Astrocyte Apoptotic Signals Induced by Hypoxia Exposure Through miR99a-5p/SERPINE1 and Alleviates Ischemic Stroke Injury

Circular RNAs are involved in intervention strategies for treating ischemic stroke (IS). However, circCNOT6L (hsa_circ_0006168) has not yet been reported in IS. Thus, we aimed to explore the potential role of circCNOT6L and its molecular mechanism in IS. In this study, we first found that the expression of both exosomal circCNOT6L (P = 0.0006) and plasma circCNOT6L (P = 0.0054) was down-regulated in IS patients compared with controls. Clinically, a negative correlation was observed between the relative expression level of circCNOT6L and the National Institutes of Health Stroke Scale (NIHSS) score and infarct volume of the brain. Simultaneously, the relative expression level of circCNOT6L was negatively associated with multiple risk factors for IS, such as mean platelet volume (MPV), red cell distribution width (RDW), very low-density lipoprotein (VLDL), and serum potassium, whereas it was positively correlated with high-density lipoprotein (HDL). In vitro, circCNOT6L silencing blocked cell viability and proliferation, while it promoted cell apoptosis of astrocytes undergoing oxygen-glucose deprivation/reperfusion (OGD/R) treatment. Mechanistically, the RNA antisense purification (RAP) assay and luciferase reporter assay revealed that circCNOT6L acts as a miRNA sponge to absorb miR-99a-5p and then regulates the expression of serine proteinase inhibitor (SERPINE1). In the further rescue experiment, overexpressing SERPINE1 could rescue the cell apoptotic signals due to circCNOT6L depletion. In conclusion, CircCNOT6L attenuated the cell apoptotic signal of astrocytes via the miR99a-5p/SERPINE1 axis and then alleviated injury after hypoxia induced by ischemic stroke.

Circ_ZNF778_006 promoted ESCC progression by upregulating HIF-1α expression via sponging miR-18b-5p

In multiple malignant tumors, circular RNAs (circRNAs) are believed to play a crucial role. Our prior results demonstrated that circ_ZNF778_006 was significantly increased in esophageal squamous cell carcinoma (ESCC) tissues, but the roles of circ_ZNF778_006 in ESCC is still not clear. The expression of circ_ZNF778_006 was compared in different pathological grades of ESCC. And the expression levels of circ_ZNF778_006, miR-18b-5p, HIF-1α were analyzed by qRT-PCR and Western blot, respectively. Plasmid transfection techniques were applied to prepare ESCC cells with silenced or overexpressed genes (CircZNF778_006, miR-18b-5p). The CCK8 kit was used to determine cell proliferation, and the Transwell assay was used to measure the migration and invasion. The effects of circ_ZNF778_006 on tumor growth was investigated in vivo. Furthermore, luciferase reporter gene assay and RNA-binding protein immunoprecipitation (RIP) were performed to verify the targeting relationship between miR-18b-5p and circZNF778_006, miR-18b-5p and HIF-1α. The expression of circ_ZNF778_006 was positively correlated with pathological grade in ESCC. Circ_ZNF778_006 significantly inhibited sensitivity to 5-fluorouracil & cisplatin. It could promote the proliferation, invasion, migration in ESCC cells and accelerated tumor growth in vivo. Furthermore, circ_ZNF778_006 could upregulate the expression of HIF-1α via sponing miR-18b-5p. Circ_ZNF778_006 promoted ESCC progression by upregulating HIF-1α expression via sponging miR-18b-5p.

CircRNA OXCT1 promotes the malignant progression and glutamine metabolism of non-small cell lung cancer by absorbing miR-516b-5p and upregulating SLC1A5

Previous study has demonstrated the high expression of circular RNA 3-oxoacid CoA-transferase 1 (circ-OXCT1) in lung adenocarcinoma tumor tissues. However, the role and possible mechanism of circ-OXCT1 in non-small cell lung cancer (NSCLC) progression was unclear.Quantitative real-time PCR (qRT-PCR), western blotting and immunohistochemistry (IHC) staining assay were performed to detect the expression of circ-OXCT1, microRNA-516b-5p (miR-516b-5p), solute carrier family 1 member 5 (SLC1A5) and other indicated protein markers. Cell proliferation was measured by Cell counting kit 8 (CCK8), colony formation and 5-Ethynyl-2'-deoxyuridine (EdU) assays. Flow cytometry was employed to detect the rate of apoptotic cells. Cell migration and invasion were measured using transwell assay. The relative glutamine uptake and α-ketoglutarate (α-KG) production was determined using commercial kits. Interaction between miR-516b-5p and circ-OXCT1 or SLC1A5 was predicted by bioinformatics analysis and confirmed via luciferase reporter and RNA immunoprecipitation (RIP) assays. In vivo assay was implemented to demonstrate the effect of circ-OXCT1 in tumor growth.Circ-OXCT1 and SLC1A5 were upregulated and miR-516b-5p was downregulated in NSCLC tissues and cells. Functional experiments revealed that circ-OXCT1 silencing suppressed cell proliferation, migration and invasion, but promoted cell apoptosis in vitro. Circ-OXCT1 knockdown repressed tumor formation in vivo. Besides, miR-516b-5p was a target of circ-OXCT1, and miR-516b-5p inhibitor could relieve circ-OXCT1 absence-mediated effects in NSCLC cells. SLC1A5 was identified as a target of miR-516b-5p. Circ-OXCT1 promoted SLC1A5 expression by target binding with miR-516b-5p.Circ-OXCT1 facilitated NSCLC progression via miR-516b-5p-dependent regulation of SLC1A5, which provided a possible circRNA-targeted therapy for NSCLC.

Propofol Suppresses Glioma Tumorigenesis by Regulating circ_0047688/miR-516b-5p/IFI30 Axis

Propofol has recently attracted increasing attention for its anti-tumor property in cancers, including glioma. Circular RNAs (circRNAs) can act as key regulators in various cancers. However, the relationship between propofol and circ_0047688 in glioma is still unclear. Cell proliferation was evaluated by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and colony formation assays. Cell migration and invasion were determined using transwell assay. Cell apoptosis was detected by flow cytometry. Protein levels and RNA levels were detected by western blot assay and real-time quantitative polymerase chain reaction (RT‑qPCR), respectively. The intermolecular interaction was predicted by bioinformatics analysis and verified by dual-luciferase reporter assay. A mouse xenograft model was established for in vivo experiments. Propofol inhibited cell proliferation, migration, and invasion and accelerated apoptosis in glioma cells. Circ_0047688 was upregulated in glioma tissues and cells, and propofol downregulated circ_0047688 in a dose-dependent manner. Circ_0047688 knockdown inhibited glioma cell progression and its overexpression abated the anti-tumor role of propofol in glioma cells. Moreover, miR-516b-5p was a direct target of circ_0047688, and circ_0047688 promoted glioma cell progression by sponging miR-516b-5p. In addition, IFI30 was a direct target of miR-516b-5p, and miR-516b-5p inhibited glioma cell malignant behaviors by targeting IFI30 in propofol-treated cells. Furthermore, circ_0047688 overexpression could weaken the anti-tumor role of propofol in vivo. Propofol inhibited glioma progression via modulating circ_0047688/miR-516b-5p/IFI30 axis, providing a potential therapeutic strategy for treatment of glioma.

Circ_CHMP5 aggravates oxidized low-density lipoprotein-induced damage to human umbilical vein endothelial cells through miR-516b-5p/TGFβR2 axis

BACKGROUND

Atherosclerosis (AS) was one of the main causes of death in the elderly, and lesions in human umbilical vein endothelial cells (HUVECs) could lead to AS. CircRNA-charged multivesicular body protein 5 (circ_CHMP5) was reported to participate in the progression of AS.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze the levels of circ_CHMP5, miR-516b-5p, and transforming growth factor beta receptor 2 (TGFβR2) in AS patients or ox-LDL-induced HUVECs. 5-Ethynyl-2'-deoxyuridine and cell counting kit-8 assays were performed to detect cell proliferation. Proteins expression was assessed by western blot assay. Cell apoptosis was examined by flow cytometry. Tube formation assay was utilized to measure the tube formation ability of HUVCEs. The targeting relationships between miR-516b-5p and circ_CHMP5 or TGFβR2 were confirmed by dual-luciferase reporter assay and RNA-pull down assay.

RESULTS

Circ_CHMP5 was enhanced in the serum of AS patients and ox-LDL-exposure HUVECs. Ox-LDL blocked proliferation and tube formation of HUVECs and induced cell apoptosis, and circ_CHMP5 knockdown reversed these effects. In addition, circ_CHMP5 regulated the growth of ox-LDL-induced HUVECs through miR-516b-5p and TGFβR2. Moreover, the effects of circ_CHMP5 knockdown on ox-LDL-induced HUVECs were obviously recovered by downregulation of miR-516b-5p, and overexpression of TGFβR2 restored the effects of miR-516b-5p upregulation on ox-LDL-stimulated HUVECs.

CONCLUSION

Silence of circ_CHMP5 overturned ox-LDL-treated inhibition of HUVECs proliferation and angiogenesis by miR-516b-5p and TGFβR2. These results provided new solutions for the treatment of AS.

The hsa-miR-516a-5p and hsa-miR-516b-5p microRNAs reduce the migration and invasion on T98G glioblastoma cell line

microRNAs (miRNAs) are involved in numerous functions and processes in the brain and other organs through the regulation of gene and protein expression. miRNA dysregulation is associated with the development of several diseases, including the brain and Central Nervous System cancer (CNS). The hsa-miR-516a-5p and hsa-miR-516b-5p are involved in proliferation, migration, and invasion in different tumor models, but their antitumor effect has not been evaluated in cancer of CNS. Therefore, we aimed to assess the effect of the miRNAs hsa-miR-516a-5p and miRNA hsa-miR-516b-5p on the Glioblastoma cell line (T98G). We used synthetic miRNA mimics to induce the overexpression of both miRNAs in the cell line, which was corroborated by RT-qPCR. Next, we evaluated the effect on proliferation, migration, and invasion using the CyQuant direct kit, ThinCert ™ inserts and invasion BioCoat ™ Matrigel® Invasion Chambers. We found upregulation of these miRNAs induced significant changes on the migration and invasion processes of T98G cells, but not affected the proliferation rate. These results suggest that both microRNAs could be playing an important role in the control of tumor progression towards metastasis. The bioinformatics analysis showed that target genes for these miRNAs are involved in different biological processes such as in cell adhesion molecule binding and cell junction disassembly, which are important for cancer progression. Further studies and experimental validation are needed to identify the genes regulated by microRNAs.

Elevated Hexose-6-Phosphate Dehydrogenase Regulated by OSMR-AS1/hsa-miR-516b-5p Axis Correlates with Poor Prognosis and Dendritic Cells Infiltration of Glioblastoma

Objective Glioblastoma (GBM), a type of malignant glioma, is the most aggressive type of brain tumor and is associated with high mortality. Hexose-6-phosphate dehydrogenase (H6PD) has been detected in multiple tumors and is involved in tumor initiation and progression. However, the specific role and mechanism of H6PD in GBM remain unclear. Methods We performed pan-cancer analysis of expression and prognosis of H6PD in GBM using the Genotype-Tissue Expression Project (GTEx) and The Cancer Genome Atlas (TCGA). Subsequently, noncoding RNAs regulating H6PD expression were obtained by comprehensive analysis, including gene expression, prognosis, correlation, and immune infiltration. Finally, tumor immune infiltrates related to H6PD and survival were performed. Results Higher expression of H6PD was statistically significantly associated with an unfavorable outcome in GBM. Downregulation of hsa-miR-124-3p and hsa-miR-516b-5p in GBM was detected from GSE90603. Subsequently, OSMR-AS1 was observed in the regulation of H6PD via hsa-miR-516b-5p. Moreover, higher H6PD expression significantly correlated with immune infiltration of dendritic cells, immune checkpoint expression, and biomarkers of dendritic cells. Conclusions The OSMR-AS1/ miR-516b-5p axis was identified as the highest-potential upstream ncRNA-related pathway of H6PD in GBM. Furthermore, the present findings demonstrated that H6PD blockading might possess antitumor roles via regulating dendritic cell infiltration and immune checkpoint expression.

Current advances and future perspectives on the functional roles and clinical implications of circular RNAs in esophageal squamous cell carcinoma: more influential than expected

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive gastrointestinal cancers with high incidence and mortality. Therefore, it is necessary to identify novel sensitive and specific biomarkers for ESCC detection and treatment. Circular RNAs (circRNAs) are a type of noncoding RNAs featured by their covalently closed circular structure. This special structure makes circRNAs more stable in mammalian cells, coupled with their great abundance and tissue specificity, suggesting circRNAs may present enormous potential to be explored as valuable prognostic and diagnostic biomarkers for tumor. Mounting studies verified the critical roles of circRNAs in regulating ESCC cells malignant behaviors. Here, we summarized the current progresses in a handful of aberrantly expressed circRNAs, and elucidated their biological function and clinical significance in ESCC, and introduced a series of databases for circRNA research. With the improved advancement in high-throughput sequencing and bioinformatics technique, new frontiers of circRNAs will pave the path for the development of precision treatment in ESCC.

NEDD4L inhibits cell viability, cell cycle progression, and glutamine metabolism in esophageal squamous cell carcinoma via ubiquitination of c-Myc

Esophageal squamous cell carcinoma (ESCC) is a common subtype of esophageal cancer with high incidence. Surgery remains the main strategy for treatment of ESCC at early stage. However, the treatment outcome is unsatisfactory. Therefore, finding new therapeutics is of great importance. In the present study, we measured the level of NEDD4L, an ubiquitin protein ligase, in clinical samples and investigated the effects of NEDD4L on cell viability, cell cycle progression, and glutamine metabolism in TE14 cells determined by CCK-8 assay, flow cytometry and biochemical analysis, respectively. The results show that NEDD4L is significantly decreased in ESCC specimens, and its decreased expression is associated with a poor clinical outcome. Overexpression of NEDD4L significantly inhibits cell viability, cell cycle progression, and glutamine metabolism in TE14 cells. Mechanistic study indicates that NEDD4L regulates tumor progression through ubiquitination of c-Myc and modulation of glutamine metabolism. NEDD4L inhibits cell viability, cell cycle progression, and glutamine metabolism in ESCC by ubiquitination of c-Myc to decrease the expressions of GLS1 and SLC1A5. Our findings highlight the importance of NEDD4L/c-Myc signaling in ESCC.

Establishment and Validation of a Ferroptosis-Related Long Non-Coding RNA Signature for Predicting the Prognosis of Stomach Adenocarcinoma

Background: Ferroptosis is a form of regulated cell death that follows cell membrane damage and mostly depends on iron-mediated oxidative. Long non-coding RNAs (LncRNAs) are associated with the development of a variety of tumors. Till date, LncRNAs have been reported to intervene in ferroptosis. Therefore, we intended to provide a prognostic ferroptosis-related-lncRNA signature in stomach adenocarcinoma (STAD).

Methods: We downloaded ferroptosis-related genes from the FerrDb database and RNA sequencing data and clinicopathological characteristics from The Cancer Genome Atlas. Gene differential expression analysis was performed using the “limma” package. We used Cox regression analysis to determine the ferroptosis-related lncRNAs signature with the lowest AIC value. The Kaplan–Meier curve, ROC curve, and nomogram were used to evaluate the prognostic value of the risk score. Gene set enrichment analysis (GSEA) was used to explore the biologic functions of the three ferroptosis-related lncRNAs. LINC01615 expression in gastric cancer cell lines and tissues was measured by real-time PCR. A nuclear-cytoplasmic fractionation assay was used to analyze the subcellular localization for LINC01615. Furthermore, we used bioinformatics to predict potential target microRNAs (miRNAs) of LINC01615 and their target ferroptosis-related mRNAs.

Results: Three ferroptosis-related-lncRNA signatures (AP000695.2, AL365181.3, and LINC01615) were identified, and then Kaplan–Meier, Cox regression analyses, and ROC curve confirmed that the ferroptosis-related-lncRNA model could predict the prognosis of STAD. The GSEA indicated that the three ferroptosis-related lncRNAs might be related to the extracellular matrix and cellular activities. LINC01615 is highly expressed in gastric cancer cell lines and tissues. A nuclear-cytoplasmic fractionation assay confirmed that in gastric cancer cell lines, most LINC01615 was enriched in the cytoplasm. Bioinformatics further predicts four potential target miRNAs of LINC01615 and then figured out 26 target ferroptosis-related mRNAs.

Conclusion: We established a three-ferroptosis-related-lncRNA model (AP000695.2, AL365181.3, and LINC01615) that can predict the prognosis of STAD patients. We also expected to provide a promising target for LINC01615 for research in the future, which was highly expressed in gastric cancer and cell lines and acted as a ceRNA to get involved in ferroptosis.

EIF4A3-induced circCCNB1 (hsa_circ_0001495) promotes glioma progression by elevating CCND1 through interacting miR-516b-5p and HuR

To explore the functions of circRNA cyclin B1 (circCCNB1) in glioma and its possible mechanisms. The expression of circCCNB1, eukaryotic translation initiation factor 4A3 (EIF4A3), cyclin D1 (CCND1) and miR-516b-5p was determined by qRT-PCR, western blot or immunohistochemistry (IHC) assay. The feature of circCCNB1 was analyzed by Actinomycin D (ActD), RNase R and subcellular fraction assays. The molecule relationships were analyzed by RIP, dual-luciferase reporter and RNA pull-down assays. CCK-8, EdU and colony formation assays were performed to analyze cell proliferation. Flow cytometry analysis was executed to estimate the cell cycle. Murine xenograft model assay was used for the role of circCCNB1 in vivo. CircCCNB1 was overexpressed in glioma tissues and cells. EIF4A3 positively regulated circCCNB1 expression. CircCCNB1 knockdown repressed glioma cell proliferation and cell cycle process in vitro and blocked tumor growth in vivo. CircCCNB1 knockdown reduced CCND1 expression in glioma cells and CCND1 overexpression bated the effect of circCCNB1 knockdown on glioma cell growth. CircCCNB1 interacted with HuR to elevate CCND1 expression. miR-516b-5p could interact with circCCNB1 and CCND1. CircCCNB1 regulated glioma cell progression and CCND1 expression by miR-516b-5p and HuR. CircCCNB1 aggravated glioma cell growth by elevating CCND1 through targeting miR-516b-5p and HuR.

MicroRNA Alterations Induced in Human Skin by Diesel Fumes, Ozone, and UV Radiation

Epigenetic alterations are a driving force of the carcinogenesis process. MicroRNAs play a role in silencing mutated oncogenes, thus defending the cell against the adverse consequences of genotoxic damages induced by environmental pollutants. These processes have been well investigated in lungs; however, although skin is directly exposed to a great variety of environmental pollutants, more research is needed to better understand the effect on cutaneous tissue. Therefore, we investigated microRNA alteration in human skin biopsies exposed to diesel fumes, ozone, and UV light for over 24 h of exposure. UV and ozone-induced microRNA alteration right after exposure, while the peak of their deregulations induced by diesel fumes was reached only at the end of the 24 h. Diesel fumes mainly altered microRNAs involved in the carcinogenesis process, ozone in apoptosis, and UV in DNA repair. Accordingly, each tested pollutant induced a specific pattern of microRNA alteration in skin related to the intrinsic mechanisms activated by the specific pollutant. These alterations, over a short time basis, reflect adaptive events aimed at defending the tissue against damages. Conversely, whenever environmental exposure lasts for a long time, the irreversible alteration of the microRNA machinery results in epigenetic damage contributing to the pathogenesis of inflammation, dysplasia, and cancer induced by environmental pollutants.

Ginsenoside Rg3 inhibits osteosarcoma progression by reducing circ_0003074 expression in a miR-516b-5p/KPNA4-dependent manner

Background

Previous data have suggested that ginsenoside Rg3 (Rg3), isolated from the roots of Panax ginseng, plays a repressing role in multiple cancers, including osteosarcoma (OS). However, there is no any literature available about the role of circular RNA (circRNA) in Rg3-mediated OS development. The study aimed to explore the function of circ_0003074 in the anti-cancer effects of Rg3 on OS.

Methods

RNA expression of circ_0003074, miR-516b-5p and karyopherin subunit alpha 4 (KPNA4) was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Protein expression was evaluated by Western blotting or immunohistochemistry assay. Cell viability, proliferation, apoptosis, migration and invasion were investigated by cell counting kit-8, 5-ethynyl-29-deoxyuridine (EdU), flow cytometry analysis, wound-healing and transwell invasion assays, respectively. Dual-luciferase reporter and/or RNA immunoprecipitation assay was performed to confirm the interplay between miR-516b-5p and circ_0003074 or KPNA4. Xenograft mouse model assay was conducted to reveal the effect of Rg3 treatment on tumor formation.

Results

Circ_0003074 and KPNA4 expression was significantly upregulated, while miR-516b-5p was downregulated in OS tissues and cells compared with controls. Rg3 treatment dramatically decreased circ_0003074 expression in OS cells. Rg3 treatment led to decreased cell proliferation, migration and invasion but increased cell apoptosis, which was attenuated after circ_0003074 overexpression. Besides, miR-516b-5p was a target miRNA of circ_0003074 and partially restored circ_0003074-mediated action under Rg3 treatment. Decreasing miR-516b-5p expression also promoted Rg3-treated OS cell malignancy through KPNA4, which was identified as a target mRNA of miR-516b-5p. Besides, circ_0003074 induced KPNA4 production owing to the decrease of miR-516b-5p expression. Furthermore, Rg3 treatment inhibited tumor formation by regulating circ_0003074 in vivo.

Conclusion

Rg3 inhibited OS progression through circ_0003074/miR-516b-5p/KPNA4 axis, showing the potential of Rg3 as a therapeutic agent for OS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02868-7.

Circ_0003074 expression was upregulated in OS tissues and cells.

Rg3 treatment significantly decreased circ_0003074 expression in OS cells.

Circ_0003074 overexpression rescued Rg3-induced inhibition in OS progression.

Circ_0003074 induced KPNA4 production through miR-516b-5p under Rg3 treatment.