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The N7-methylguanosine (m7G) modification and circular RNAs (circRNAs) have been shown to play important roles in the development of lung cancer. However, the m7G modification of circRNAs has not been fully elucidated. This study revealed the presence of the m7G modification in circFAM126A. We propose the novel hypothesis that the methyltransferase TRMT10C mediates the m7G modification of circFAM126A and that the stability of m7G-modified circFAM126A is reduced. circFAM126A is downregulated in lung cancer and significantly inhibits lung cancer growth both in vitro and in vivo. The expression of circFAM126A correlates with the stage of lung cancer and with the tumour diameter, and circFAM126A can be used as a potential molecular target for lung cancer. The molecular mechanism by which circFAM126A increases HSP90 ubiquitination and suppresses AKT1 expression to regulate cellular glycolysis, ultimately inhibiting the progression of lung cancer, is elucidated. This study not only broadens the knowledge regarding the expression and regulatory mode of circRNAs but also provides new insights into the molecular mechanisms that regulate tumour cell metabolism and affect tumour cell fate from an epigenetic perspective. These findings will facilitate the development of new strategies for lung cancer prevention and treatment. Graphical Headlights • circRNA can undergo m7G modification. The methyltransferase TRMT10C mediates circFAM126A m7G modification, thereby enhancing circFAM126A stability. • m7G-modified circFAM126A can perform a biological function in inhibiting lung cancer progression by regulating cellular glycolysis. • circFAM126A increases ubiquitination of HSP90 and inhibits AKT1 expression to regulate cellular glycolysis. [ABSTRACT FROM AUTHOR]

Lung cancer is the primary cause of cancer-related death worldwide, and its global incidence and mortality rates remain high. The differential expression of circular RNAs (circRNAs) can affect the development of cancer, but the mechanisms by which circRNAs regulate lung cancer progression remain unclear. In this study, we identified circSORBS1, a circRNA that has not been previously described in lung cancer and is significantly underexpressed in lung cancer tissues, blood and cell lines, and the low expression of circSORBS1 correlated with tumour grade and prognosis. In vitro and in vivo functional experiments revealed that circSORBS1 overexpression inhibited cell proliferation and migration while enhancing apoptosis. Mechanistically, circSORBS1 acts as a sponge for miR-6779-5p, indirectly inhibiting RUFY3 mRNA degradation. Simultaneously, it binds to RUFY3 mRNA to enhance its stability. This dual regulatory mechanism leads to an increase in RUFY3 protein levels, which ultimately activates the YWHAE/BAD/BCL2 apoptotic signalling pathway and suppresses lung cancer progression. Our findings not only increase the knowledge about the regulatory pattern of circRNA expression but also provide new insights into the mechanisms by which circRNAs regulate lung cancer development. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Accumulating evidence indicates that circular RNAs (circRNAs) are inextricably linked to cancer development. However, the function and mechanism of nucleus‐localized circRNAs in hepatocellular carcinoma (HCC) still require investigation. Here, qRT‐PCR and receiver‐operating characteristic curve were used to detect the expression and diagnostic potential of circSLC39A5 for HCC. The biological function of circSLC39A5 in HCC was investigated in vitro and in vivo. Nucleoplasmic separation assay, fluorescence in situ hybridization, RNA pulldown, RNA immunoprecipitation, the HDOCK Server, the NucleicNet Webserver, crosslinking‐immunoprecipitation, MG132 treatment, and chromatin immunoprecipitation were utilized to explore the potential molecular mechanism of circSLC39A5 in HCC. The results showed that circSLC39A5 was downregulated in both HCC tissues and plasma and was associated with satellite nodules and lymph node metastasis/vascular invasion. CircSLC39A5 was stably expressed in plasma samples under different storage conditions, showing good diagnostic potential for HCC (AUC = 0.915). CircSLC39A5 inhibited proliferation, migration, and invasion, facilitated the apoptosis of HCC cells, and was associated with low expression of Ki67 and CD34. Remarkably, circSLC39A5 is mainly localized in the nucleus and binds to the transcription factor signal transducer and activator of transcription 1 (STAT1), affecting its stabilization and expression. STAT1 binds to the promoter of thymine DNA glycosylase (TDG). Overexpression of circSLC39A5 elevates TDG expression and reverses the increase of proliferating cell nuclear antigen (PCNA) expression and the overactive cell proliferation caused by TDG silencing. Our findings uncovered a novel plasma circRNA, circSLC39A5, which may be a potential circulating diagnostic marker for HCC, and the mechanism by which nucleus‐localized circSLC39A5 exerts a transcriptional regulatory role in HCC by affecting STAT1/TDG/PCNA provides new insights into the mechanism of circRNAs. [ABSTRACT FROM AUTHOR]

Background: Many studies have shown that circular RNAs (circRNAs) are abnormally expressed in various tumor tissues and served as a key regulator in the occurrence and development of cancer. However, in hepatocellular carcinoma (HCC), the molecular mechanism of circRNAs in body fluids remains to be further explored. Methods: The expression levels of genes and proteins were detected by quantitative real‐time polymerase chain reaction (qRT‐PCR) and western blotting, respectively. Cell counting Kit‐8 (CCK‐8), 5‐Ethynyl‐2'‐deoxyuridine (EdU), wound healing assay, Transwell assays, flow cytometry, and tumor formation models in nude mice were conducted to investigate the effects of circFAM114A2 on HCC cells both in vitro and in vivo. RNA antisense purification (RAP), dual luciferase reporter assays and rescue assays were carried out to verify the interaction between circFAM114A2, miR‐630 and HHIP. Results: CircFAM114A2 was significantly downregulated in HCC tissues and was associated with microvascular invasion and lymph node metastasis of HCC patients. We also observed that circFAM114A2 was lowly expressed in HCC plasma, which may serve as an effective biomarker to screen HCC patients from healthy controls (area under curve (AUC)=0.922). In vitro, circFAM114A2 overexpression significantly blunted HCC cell proliferation, migration, invasion, and promoted apoptosis, whereas circFAM114A2 silencing posed opposite effects. In vivo, circFAM114A2 overexpression inhibited the growth of HCC cells. Mechanistically, circFAM114A2 could increase the expression of the tumor suppressor HHIP via acting as a sponge for miR‐630. Conclusions: CircFAM114A2 exerts a tumor suppressor role in HCC through miR‐630/HHIP axis, and may be served as a potential diagnostic and therapeutic biomarker for HCC patients. [ABSTRACT FROM AUTHOR]

Extensive research confirmed that circRNA can play a regulatory role in various stages of tumors by interacting with various molecules. Identifying the differentially expressed circRNA in bladder cancer and exploring its regulatory mechanism on bladder cancer progression are urgent. In this study, we screened out a circRNA-circGLIS3 with a significant upregulation trend in both bladder cancer tissues and cells. Bioinformatics prediction results showed that circGLIS3 may be involved in multiple tumor-related pathways. Function gain and loss experiments verified circGLIS3 can affect the proliferation, migration, and invasion of bladder cancer cells in vitro. Moreover, silencing circGLIS3 inhibited bladder cancer cell growth in vivo. Subsequent research results indicated circGLIS3 regulated the expression of cyclin D1, a cell cycle–related protein, and cell cycle progression. Mechanically, circGLIS3 upregulates the expression of SKP1 by adsorbing miR-1273f and then promotes cyclin D1 expression, ultimately promoting the proliferation of bladder cancer cells. In summary, our study indicates that circGLIS3 plays an oncogene role in the development of bladder cancer and has potential to be a candidate for bladder cancer. [ABSTRACT FROM AUTHOR]

Background: Lung cancer has high morbidity and mortality worldwide with non-small cell lung cancer (NSCLC) accounting for 85% of the cases. Therapies for lung cancer have relatively poor outcomes and further improvements are required. Circular RNAs have been reported to participate in the occurrence and progression of cancer. Information on the functions and mechanism of circRNAs in lung cancer is limited and needs more exploration. Methods: We detected expression of genes and proteins by qPCR and western blot. Function of circSATB2 was investigated using RNA interference and overexpression assays. Location of circSATB2 was assessed by fluorescence in situ hybridization (FISH). Interaction of circSATB2, miR-326 and FSCN1 was confirmed by dual-luciferase reporter assay. Results: Data from the investigation showed that circSATB2 was highly expressed in NSCLC cells and tissues. circSATB2 positively regulated fascin homolog 1, actin-bundling protein 1 (FSCN1) expression via miR-326 in lung cancer cells. Furthermore, circSATB2 can be transferred by exosomes and promote the proliferation, migration and invasion of NSCLC cells, as well as induce abnormal proliferation in normal human bronchial epithelial cells. Also, circSATB2 was highly expressed in serumal exosomes from lung cancer patients with high sensitivity and specificity for clinical detection and was related to lung cancer metastasis. Conclusions: circSATB2 participated in the progression of NSCLC and was differentially expressed in lung cancer tissue and serumal exosomes. circSATB2 may be potential biomarker for the diagnosis of NSCLC. [ABSTRACT FROM AUTHOR]

Smoking is one of the major environmental risk factors for lung cancer. In recent years, the role of long-chain noncoding RNAs (lncRNAs) in chemical carcinogenesis has attracted extensive research attention. In this study, we treated human bronchial epithelial cells with cigarette smoke extract (CSE) at a dose of 2 μg/ml to establish a malignantly transformed cellular model (16HBE-M). Screening of lncRNAs highly expressed in transformed cells via differential analysis revealed a crucial role of linc00152 in CSE-induced malignant transformation. The linc00152 serum level in CSE-exposed individuals was increased in a dose-dependent manner and its high expression associated with metastasis and proliferation of lung cancer tissue. In malignantly transformed 16HBE-M cells, linc00152 was involved in regulation of cell adhesion, epithelial transition and other malignant phenotypes, which in turn, affected in vivo metastasis. Interference with linc00152 expression led to G1/S arrest and inhibition of proliferation of 16HBE-M and H1299 cells. Furthermore, linc00152 promoted cyclin D1 expression and G1/S transition by functioning as an endogenous competitive RNA targeting miR-193b. Our collective findings supported a critical regulatory role of linc00152 in cell cycle alterations and abnormal proliferation in CSE-induced malignant transformation of human bronchial epithelial cells. [ABSTRACT FROM AUTHOR]

Lead is a heavy metal pollutant that is widely present in the environment and can seriously harm human health, especially the nervous system. Long noncoding RNAs (lncRNAs) play important roles in many physiological and pathological processes; however, there remains a lack of in-depth studies on the molecular mechanisms associated with lead neurotoxicity. Here, our results showed that lead exposure inhibited cell proliferation and promoted cell apoptosis. We observed that lncRNAL20992 was significantly upregulated in a lead-induced neuronal-injury cell model according to quantitative reverse transcription polymerase chain reaction. Silencing lncRNAL20992 revealed its significant functions involved in promoting cell apoptosis and inhibiting cell proliferation according to cell-counting kit-8, EdU assay, terminal deoxynucleotidyl transferase dUTP nick-end labeling, and western blot. To elucidate the molecular mechanisms of lncRNAL20992, we used RNA pulldown mass spectrometry combined with bioinformatics analysis to discover 4 proteins (AIFM1, HSP7C, GRP78, and LMNA) that interacted with lncRNAL20992. Western blot analysis indicated that lncRNAL20992 involved in lead-induced neuronal injury was mediated by the 4 proteins. Our study constitutes the first investigation of the functions and related mechanisms of lncRNAL20992 and offered valuable insight into understanding the roles of lncRNA in lead-induced neurotoxicity. [ABSTRACT FROM AUTHOR]

Lead is a metal that has toxic effects on the developing nervous system. However, the mechanisms underlying lead-induced neurotoxicity are not well understood. Non-coding RNAs (ncRNAs) play an important role in epigenetic regulation, but few studies have examined the function of ncRNAs in lead-induced neurotoxicity. We addressed this in the present study by evaluating the functions of a long non-coding RNA (named lncRpa) and a circular RNA (named circRar1) in a mouse model of lead-induced neurotoxicity. High-throughput RNA sequencing showed that both lncRpa and circRar1 promoted neuronal apoptosis. We also found that lncRpa and circRar1 induced the upregulation of apoptosis-associated factors caspase8 and p38 at the mRNA and protein levels via modulation of their common target microRNA miR- 671. This is the first report of a regulatory interaction among a lncRNA, circRNA, and miRNA mediating neuronal apoptosis in response to lead toxicity. [ABSTRACT FROM AUTHOR]

Circular RNAs are widely expressed in eukaryotic cells and associated with cancer. However, limited studies to date have focused on the potential role of circRNAs in progression of lung cancer. Data from the current investigation showed that circRNA 100146 is highly expressed in non-small cell lung cancer (NSCLC) cell lines and the chemically induced malignant transformed bronchial cell line, 16HBE-T, as well as 40 paired tissue samples of NSCLC. Suppression of circRNA 100146 inhibited the proliferation and invasion of cells and promoted apoptosis. Furthermore, circRNA 100146 could interact with splicing factors and bind miR-361-3p and miR-615-5p to regulate multiple downstream mRNAs. Our collective findings support a role of circRNA 100146 in the development of NSCLC and further demonstrate endogenous competition among circRNA 100146, SF3B3 and miRNAs, providing novel insights into the mechanisms underlying non-small cell lung cancer. [ABSTRACT FROM AUTHOR]

circNOL10 is a circular RNA expressed at low levels in lung cancer, though its functions in lung cancer remain unknown. Here, the function and molecular mechanism of circNOL10 in lung cancer development are investigated using in vitro and in vivo studies, and it is shown that circNOL10 significantly inhibits the development of lung cancer and that circNOL10 expression is co‐regulated by methylation of its parental gene Pre‐NOL10 and by splicing factor epithelial splicing regulatory protein 1 (ESRP1). circNOL10 promotes the expression of transcription factor sex comb on midleg‐like 1 (SCML1) by inhibiting transcription factor ubiquitination and thus also affects regulation of the humanin (HN) polypeptide family by SCML1. circNOL10 also affects mitochondrial function through regulating the humanin polypeptide family and affecting multiple signaling pathways, ultimately inhibiting cell proliferation and cell cycle progression, and promoting the apoptosis of lung cancer cells, thereby inhibiting lung cancer development. This study investigates the functions and molecular mechanisms of circNOL10 in the development of lung cancer and reveals its involvement in the transcriptional regulation of the HN polypeptide family by SCML1. The results also demonstrate the inhibitory effect of HN on lung cancer cells growth. These findings may identify novel targets for the molecular therapy of lung cancer. This study provides new evidence for the molecular mechanism whereby circRNAs may affect transcriptional regulation in lung cancer cells, and also reveals that circNOL10 inhibits lung cancer development by promoting SCLM1‐mediated transcriptional regulation of the humanin (HN) polypeptide family. The results also demonstrate the inhibitory effect of HN on lung cancer growth. [ABSTRACT FROM AUTHOR]