CircRNA: a rising star in gastric cancer

Identification of circRNA-miRNA-mRNA networks to explore underlying mechanism in lung cancer

Background

Circular RNAs (circRNAs) are involved in the occurrence and development of various tumors. CircRNAs can act as competing endogenous RNAs (ceRNAs), which are important regulatory networks, by regulating microRNAs (miRNAs). However, the effects of ceRNA networks on lung cancer (LC), especially the circRNA-miRNA-mRNA regulatory network, remain incompletely understood. Therefore, the aim of this study was to explore novel ceRNA networks and their function and underlying mechanisms in LC.

Methods

Six RNA expression datasets were obtained from the Gene Expression Omnibus microarray datasets (circRNA: GSE158695, GSE101684, GSE112214, and GSE101586; miRNA: GSE135918; mRNA: GSE98929). First, we constructed a circRNA-miRNA-mRNA ceRNA network in LC using Cytoscape. Second, we constructed a protein-protein interaction network using STRING and identified hub genes using CytoHubba. Functional analysis was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) to predict the potential function of the hub genes. Third, expression and survival analysis of the hub genes were performed to identify prognostic genes.

Results

We constructed a ceRNA network including 18 circRNAs, 32 miRNAs, and 135 mRNAs, and identified 10 hub genes (VEGFA, FOS, MAD2L1, CREBBP, TYMS, EDN1, RFC5, KIF11, SLC2A1, and TOP2A). Both GO and KEGG analyses revealed that the 10 hub genes were associated with several cancer‑related biological functions and pathways, including "oxygen levels", "nuclear division", and "HIF-1 signaling pathway". Five genes (MAD2L1, TYMS, KIF11, SLC2A1, and TOP2A) were associated with the prognosis of lung adenocarcinoma (LUAD), the most common histological type of LC.

Conclusion

Our study provides novel insights into the pathogenesis and therapy of LC from a ceRNA network perspective.

Dysregulated circular RNA and long non-coding RNA-Mediated regulatory competing endogenous RNA networks (ceRNETs) in ovarian and cervical cancers: A non-coding RNA-Mediated mechanism of chemotherapeutic resistance with new emerging clinical capacities

Cervical cancer (CC) and ovarian cancer (OC) are among the most common gynecological cancers with significant mortality in women, and their incidence is increasing. In addition to the prominent role of the malignant aspect of these cancers in cancer-related women deaths, chemotherapy drug resistance is a major factor that contributes to their mortality and presents a clinical obstacle. Although the exact mechanisms behind the chemoresistance in these cancers has not been revealed, accumulating evidence points to the dysregulation of non-coding RNAs (ncRNAs), particularly long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), as key contributors. These ncRNAs perform the roles of regulators of signaling pathways linked to tumor formation and chemoresistance. Strong data from various recent studies have uncovered that the main mechanism of these ncRNAs in the induction of chemoresistance of CC and OC is done through a dysregulated miRNA sponge activity as competing endogenous RNA (ceRNA) in the competing endogenous RNA networks (ceRNETs), where a miRNA regulating a messenger RNA (mRNA) is trapped, thereby removing its inhibitory effect on the desired mRNA. Understanding these mechanisms is essential to enhancing treatment outcomes and managing the problem of drug resistance. This review provides a comprehensive overview of lncRNA- and circRNA-mediated ceRNETs as the core process of chemoresistance against the commonly used chemotherapeutics, including cisplatin, paclitaxel, oxaliplatin, carboplatin, and docetaxel in CC and OC. Furthermore, we highlight the clinical potential of these ncRNAs serving as diagnostic indicators of chemotherapy responses and therapeutic targets.

Adaptive Meta-Path Selection Based Heterogeneous Spatial Enhancement for circRNA-Disease Associations Prediction

Circular RNAs (circRNAs) play a crucial role in human biological processes as miRNA sponges, regulating gene expression and affecting disease manifestations. Establishing heterogeneous nodal feature relationships through meta-paths can effectively enhance the predictive capability of models. Previous research primarily constructed associations between meta-paths manually, and excessive noise made it difficult to capture highly correlated hidden features. Equally important is learning more about feature distributions, which is key to improving the generalization ability of algorithms. To address these challenges, we propose an adaptive meta-path selection method named AdaMH. The core scheme introduces an adaptive path selection method that automatically identifies highly relevant heterogeneous meta-paths during iterative training rounds. Considering the sparsity of data distribution, we introduce controlled random noise into the data through graph contrastive learning to ensure an even distribution of features. Subsequently, a multi-head attention mechanism is utilized to capture relationships in the high-dimensional heterogeneous feature space, enhancing feature representation capability. Comparing with state-of-the-art (SOTA) algorithms, AdaMH is the only one that surpasses a performance threshold of 0.95 across seven evaluation metrics.

Unlocking the potential of circular RNA vaccines: a bioinformatics and computational biology perspective

Bioinformatics has significantly advanced RNA-based therapeutics, particularly circular RNAs (circRNAs), which outperform mRNA vaccines, by offering superior stability, sustained expression, and enhanced immunogenicity due to their covalently closed structure. This review highlights how bioinformatics and computational biology optimise circRNA vaccine design, elucidates internal ribosome entry sites (IRES) selection, open reading frame (ORF) optimisation, codon usage, RNA secondary structure prediction, and delivery system development. While circRNA vaccines may not always surpass traditional vaccines in stability, their production efficiency and therapeutic efficacy can be enhanced through computational strategies. The discussion also addresses challenges and future prospects, emphasizing the need for innovative solutions to overcome current limitations and advance circRNA vaccine applications.

Helicobacter pylori-related serum indicators: Cutting-edge advances to enhance the efficacy of gastric cancer screening

Helicobacter pylori (H. pylori) infection induces pathological changes via chronic inflammation and virulence factors, thereby increasing the risk of gastric cancer development. Compared with invasive examination methods, H. pylori-related serum indicators are cost-effective and valuable for the early detection of gastric cancer (GC); however, large-scale clinical validation and sufficient understanding of the specific molecular mechanisms involved are lacking. Therefore, a comprehensive review and analysis of recent advances in this field is necessary. In this review, we systematically analyze the relationship between H. pylori and GC and discuss the application of new molecular biomarkers in GC screening. We also summarize the screening potential and application of anti-H. pylori immunoglobulin G and virulence factor-related serum antibodies for identifying GC risk. These indicators provide early warning of infection and enhance screening accuracy. Additionally, we discuss the potential combination of multiple screening indicators for the comprehensive analysis and development of emerging testing methods to improve the accuracy and efficiency of GC screening. Although this review may lack sufficient evidence due to limitations in existing studies, including small sample sizes, regional variations, and inconsistent testing methods, it contributes to advancing personalized precision medicine in high-risk populations and developing GC screening strategies.

Comprehensive analysis of differential mRNA and circRNA profiles in primary and metastatic pancreatic neuroendocrine tumors

The diagnosis of primary pancreatic neuroendocrine tumors (pNETs) presents significant challenges, and metastatic pancreatic neuroendocrine tumors are associated with high mortality. Understanding the characteristics of these tumors, particularly the key molecules involved in metastasis, is essential. To address this, we utilized mRNA expression data from human pNET and metastatic pancreatic tumor tissues available in the GEO database and integrated this data with bioinformatics analyses. And then we collected clinical primary tumor and liver metastasis samples from patients with pNETs, we conducted a comprehensive analysis of circular RNAs (circRNAs) to identify key circRNAs associated with the onset and metastasis of pNETs. We found that in pNET development and metastasis, 11 genes and 14 circRNAs were notably upregulated, while 25 genes and 35 circRNAs were significantly downregulated, compared to nearby non-cancerous tissue. Our analysis of differentially expressed RNA and circRNA genes revealed that tumor cell adhesion and integrin activation, regulated by genes like PIEZO1, IFT74, SKAP1, GPX1, F7, VTN, and OMG, are strongly linked to pNET metastasis. We found that SKAP1 levels are positively associated with tumor progression in pNET patients. Overall, our research indicates that the SKAP1-mediated pathway is crucial in pNET development and metastasis.

Extracellular vesicles-based vaccines: Emerging immunotherapies against cancer

Cancer vaccines are promising therapeutic approaches to enhance specific T-cell immunity against most solid tumors. By stimulating anti-tumor immunity, clearing minimal residual disease, and minimizing adverse effects, these vaccines target tumor cells and are effective when combined with immune checkpoint blockade or other immunotherapies. However, the development of tumor cell-based vaccines faces quality issues due to poor immunogenicity, tumor heterogeneity, a suppressive tumor immune microenvironment, and ineffective delivery methods. In contrast, extracellular vesicles (EVs), naturally released by cells, are considered the ideal drug carriers and vaccine platforms. EVs offer highly organ-specific targeting, induce broader and more effective immune responses, and demonstrate superior tissue delivery ability. The development of EV vaccines is crucial for advancing cancer immunotherapy. Compared to cell-based vaccines, EV vaccines produced under Good Manufacturing Practices (GMP) offer advantages such as high safety, ease of preservation and transport, and a wide range of sources. This review summarizes the latest research findings on EV vaccine and potential applications in this field. It also highlights novel neoantigens for the development of EV vaccines against cancer.

Primary Cilia Formation Mediated by Hsa_Circ_0005185/OTUB1/RAB8A Complex Inhibits Prostate Cancer Progression by Suppressing Hedgehog Signaling Pathway

Prostate cancer (PCa) is one of the most common malignancies for male individuals globally. Androgen deprivation therapy (ADT) initially demonstrated significant efficacy in treating PCa; however, most cases of PCa eventually progress to castration-resistant prostate cancer (CRPC), which becomes increasingly challenging to manage. Notably, the loss or disruption of primary cilia in PCa cells may play a critical role in the progression of the disease, and there are no reports on the role of circular RNAs in ciliogenesis. Thus, this warrants further investigation.In this study, key circular RNAs linked to prostate cancer progression, and enzalutamide resistance is identified. Specifically, it is found that hsa_circ_0005185 interacts with OTUB1 and RAB8A, serving as a molecular scaffold. Hsa_circ_0005185 mediates the binding of the deubiquitinase OTUB1 to RAB8A, resulting in the deubiquitination of RAB8A. Consequently, the stable expression of RAB8A promotes the regeneration of primary cilia and enhances the production of GLI3R, an inhibitory factor in the Hedgehog signaling pathway, thereby suppressing AR activity and slowing the progression of CRPC.

Inhibition of mmu_circ_0009303 improves metabolic dysfunction-associated steatotic liver disease by regulating lipid metabolism and oxidative stress

Circular RNAs (circRNAs) play an important role in regulating inflammation and oxidative stress during the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD); however, the underlying mechanism is unclear. This study aimed to determine the role of mmu_circ_0009303 in MASLD. We used a bioinformatics approach to identify potential targets and established an in vitro model of MASLD. Oil red O staining, cell transfection and dual-luciferase reporter assay were used to determine the role of mmu_circ_0009303. The results indicated that the mmu_circ_0009303 expression was significantly increased in the MASLD model both in vitro and in vivo and was associated with oxidative stress levels and inflammation. Moreover, bioinformatics analyses revealed that miRNA-182-5p and Foxo3 are targets of mmu_circ_0009303 and miRNA-182-5p, respectively. In the in vitro MASLD model, mmu_circ_0009303 promoted fat deposition in NCTC1469 cells, which was induced by free fatty acid (FFA) through the regulation of miRNA-182-5p/Foxo3. The expression of miRNA-182-5p and Forkhead box O3 (Foxo3) was associated with mmu_circ_0009303 expression in the liver of mice with MASLD, which was induced by a high-fat diet. Furthermore, mmu_circ_0009303 may be involved in regulating the expression of lipid metabolism-related regulatory proteins, such as CPT1A, SLC27A4, ACBD3, SREBP1, FAS, PPARα, and PPARγ. Taken together, mmu_circ_0009303 promotes oxidative stress, inflammation, and excessive fat accumulation in NCTC1469 cells induced by FFA through the regulation of miRNA-182-5p/Foxo3 and lipid metabolism-related regulatory proteins. These findings provide a potential target for the treatment of MASLD.

circ-ZEB1 Enhances NSCLC Metastasis and Proliferation by Modulating the miR-491-5p/EIF5A Axis

Background: Circular RNAs (circRNAs), covalently closed single-stranded RNAs, have been implicated in cancer progression. A previous investigation revealed that circ-ZEB1 is expressed abnormally in liver cancer. However, the roles of circ-ZEB1 in non-small cell lung cancer (NSCLC) are unknown. Methods: In this study, we used fluorescence in situ hybridization (FISH) and RT-qPCR to study circ-ZEB1 expression in NSCLC cells and tissues. A luciferase reporter assay was performed to validate downstream targets of circ-ZEB1. Transwell migration, 5-ethynyl-20-deoxyuridine (EdU), and cell counting kit-8 (CCK8) assays were performed to assess proliferation and migration. In vivo metastasis and tumorigenesis assays were also performed to investigate circ-ZEB1 functions during NSCLC. Results: Our results showed that circ-ZEB1 expression was increased in NSCLC tissues and cells. circ-ZEB1 downregulation suppressed NSCLC cell proliferation as well as migration in vitro and in vivo. Luciferase data confirmed EIF5A and miR-491-5p as downstream targets of circ-ZEB1. EIF5A overexpression and miR-491-5p suppression reversed NSCLC cell migration post circ-ZEB1 silencing. Conclusion: Our collective findings advised that circ-ZEB1 takes part in the malignant progression through regulating the miR-491-5p/EIF5A axis, highlighting its potential as an effective NSCLC therapeutic target.

Silencing circ_0043256 inhibited CoCl2-induced proliferation, migration, and aerobic glycolysis in gastric cancer cells

We aimed to explore the role of circular RNA 0043256 (circ_0043256) in gastric cancer (GC) and its underlying mechanisms. The impact of circ_0043256 silencing on the proliferation, migration, apoptosis, and aerobic glycolysis of MKN-45 and AGS cells induced by CoCl2 was assessed through the utilization of CCK-8, wound healing assay, flow cytometry, and metabolic analysis. The interaction between circ_0043256 and miR-593-5p, as well as the involvement of the miR-593-5p/RRM2 axis in gastric cancer, were confirmed via luciferase assay, Western blot, and bioinformatics analysis. We found that circ_0043256 was up-regulated in GC tissues and CoCl2-treated MKN-45 and AGS cells. Silencing of circ_0043256 reversed CoCl2-induced proliferation, migration, and aerobic glycolysis in MKN-45 and AGS cells. Additionally, circ_0043256 silencing enhanced cell apoptosis and G2/M phase cell cycle arrest in response to CoCl2 treatment. Furthermore, the miR-593-5p/RRM2 axis was identified as a regulatory mechanism for circ_0043256 function in GC. Silencing of circ_0043256 and miR-593-5p mimic co-transfection significantly inhibited CoCl2-induced cellular responses in MKN-45 and AGS cells. A glycolysis inhibitor 2-DG further enhanced the inhibitory effect of circ_0043256 silencing on aerobic glycolysis of CoCl2-induced MKN-45 and AGS cells. Additionally, the inhibition of circ_0043256 resulted in a reduction in tumor volume and the expression of proliferation marker proteins in nude mice. Moreover, the suppression of circ_0043256 led to an increase in miR-593-5p expression and a decrease in RRM2 expression, ultimately causing a decrease in glycolytic-related proteins associated with the glycolytic pathway. Targeting this axis may offer a novel therapeutic approach for treating GC.

Expression and Significance of the Circular RNA circ_0001438 in the Development of Gastric Cancer

Gastric cancer has become a great challenge to human health in the world. We studied the expression and role of the circular RNA 0001438 (circ_0001438) with the aim of finding a biomarker to assess the prognosis of gastric cancer. Through a polymerase chain reaction, circ_0001438 expression in gastric cancer was detected. Chi-square test, multi-factor Cox regression, and Kaplan-Meier analyses were used to determine the association between circ_0001438 and the patients' clinical condition and prognosis. Using the luciferase reporter gene system, the interaction between circ_0001438 and miR-1290 was analyzed, and the regulatory impact of circ_0001438/miR-1290 on the activity of gastric cancer cells was examined flowing the Transwell assay and CCK8 assay. In gastric cancer tissues and cells, circ_0001438 expression was downregulated, and miR-1290 expression was upregulated and the two were negatively correlated. miR-1290 inhibitors were transfected and significantly increased the activity of circ_0001438 luciferase, while miR-1290 mimics decreased the activity. Overexpression of circ_0001438 decreased miR-1290 expression and inhibited the proliferation and metastasis of gastric cancer cells, which was reversed when miR-1290 mimics were transfected. Additionally, there was a correlation between circ_0001438 expression and lymph node metastases, tumor size, and TNM stage of gastric cancer. Low circ_0001438 expression predicts poor prognosis of gastric cancer patients. circ_0001438 is a biomarker for tumor development and clinical prognosis in gastric cancer. It works by downregulating miR-1290 to control the activity of gastric cancer cells.

Molecular mechanism of RB progression and Circ_0082415 inhibits MKLN1 translation to suppress retinoblastoma progression: Changes in mRNA and protein levels

The molecular mechanism of retinoblastoma (RB) is complex, involving the abnormal regulation of many genes and signaling pathways. The objective of this research was to explore the molecular mechanisms underlying the role of Circ_0082415 in the progression of retinoblastoma (RB), with particular emphasis on its suppressive impact on the translation of MKLN1 and its consequent influence on the advancement of RB. The study quantified the expression levels of Circ_0082415 in both RB cells and normal retinal cells using quantitative reverse transcription polymerase chain reaction (qRT-PCR), and subsequently analyzed the trend of Circ_0082415 expression throughout the progression of RB. The interaction mechanism between Circ_0082415 and MKLN1 mRNA was investigated by bioinformatics analysis and double luciferase reporter gene experiment. The expression of Circ_0082415 was markedly reduced in retinoblastoma (RB) cells, and its expression level exhibited a negative correlation with RB progression. Notably, the upregulation of Circ_0082415 significantly suppressed the proliferation, migration, and invasion of RB cells. A dual luciferase reporter gene assay substantiated the interaction between Circ_0082415 and MKLN1 mRNA, elucidating the mechanism through which Circ_0082415 exerts its anti-tumor effects by impeding the translation of MKLN1.

Studying the non-coding RNA expression and its role in drug resistance mechanisms of gastric cancer

Gastric cancer is the fifth most common malignancy and the fifth primary cause of death from cancer all over the world. Because of diagnosis of gastric cancer at advanced, incurable stages and limited response to treatment, the disease has an adverse prognosis and a low survival rate. Chemotherapy consisting of medications such as platinum and 5-Fluorouracil can be effective for patients with advanced stomach cancer. Nevertheless, drug resistance eventually leads to unsuccessful therapy and adverse outcomes for gastric cancer patients. Most therapy failures in gastric cancer patients undergoing chemotherapy are caused by the development of drug resistance. Several studies have shown that noncoding RNAs (ncRNAs) play important roles in the resistance of gastric cancer to chemotherapy drugs. The development of stomach cancer is greatly impacted by a number of ncRNAs, including microRNAs (e.g., miR-21, miR-27a), circular RNAs (e.g., CircPVT1), and long noncoding RNAs (e.g., HOTAIR). Because of their regulatory characteristics in certain genes implicated in the chemoresistant phenotype of gastric cancer, much evidence has demonstrated their function in the emergence and persistence of drug resistance. In the future, ncRNA-based treatment could represent a novel approach to treating drug resistance. Despite numerous studies on anticancer drug resistance mechanisms, it is still unclear how these mechanisms are regulated. In this review, we investigated the evolving function and molecular mechanisms of ncRNAs related to drug resistance, their function in controlling drug resistance in gastric cancer, and their potential to create targeted therapeutics for reducing drug resistance in gastric cancer.

Research trends and hotspots in gastric carcinoma associated exosome: a bibliometric analysis

Background

Stomach cancer is considered the fifth most common cancer worldwide. This study utilized bibliometric analysis to construct a visualization map of the relationship between stomach cancer and exosomes, aiming to reveal research trends and emerging themes, and provide direction for future research.

Method

Retrieve relevant literature on gastric cancer exosomes in the Web of Science Core Collection (WoSCC) over the past 25 years according to search criteria, and conduct bibliometric and visualization analysis using bibliometric software VOSviewer and CiteSpace.

Results

This study included a total of 727 articles, with an overall increasing trend in annual publication output. There were 68 countries involved, with China having the largest number of publications followed by the United States. A total of 957 research institutions were involved, with most of the top 10 institutions in terms of publication output being universities in China. The top 5 journals are Molecular Cancer, Cell death & disease, Cancers, International journal of molecular sciences, and Frontiers in oncology. A total of 4529 authors were involved, with 5 authors having a publication output of no less than 13 articles. A total of 35516 references were cited, with a total number of citations. The top publication is "Exosome-mediated transfer of mRNAs and microRNAs is a novel mechanism of genetic exchange between cells".

Conclusion

Over the past 25 years, researchers have been dedicated to studying the field of exosomes related to gastric cancer, and research in this area is currently progressing steadily. Based on previous studies, exosomes in gastric adenocarcinoma serve as biomarkers, potential therapeutic targets, and post-resistance treatment, which represents current hotspots and emerging frontiers in research.

Circulating non-coding RNA in type 1 diabetes mellitus as a source of potential biomarkers - An emerging role of sex difference

Non-coding RNAs (ncRNAs), such as microRNA, long non-coding RNA, and circular RNA, are considered essential regulatory molecules mediating many cellular processes. Moreover, an increasing number of studies have investigated the role of ncRNAs in cancers and various metabolic disorders, including diabetes mellitus. Interestingly, some circulating ncRNA detected in body fluids may serve as novel biomarkers. There is still a lack of conventional biomarkers that detect the early stage of type 1 diabetes mellitus. Many circulating microRNA, long non-coding RNA, and circular RNA show aberrant expression in type 1 diabetes patients compared to healthy individuals. However, most studies have focused on circulating microRNA rather than long non-coding RNA or circular RNA. In addition, a few studies have evaluated sex differences in ncRNA biomarkers. Therefore, this article summarises current knowledge about circulating ncRNAs as potential biomarkers for type 1 diabetes and explores the effects of sex on such biomarkers.

The potential of circular RNAs as biomarkers and therapeutic targets for gastric cancer: A comprehensive review

BACKGROUND

Gastric cancer (GC) is a global health concern, contributing significantly to cancer-related mortality rates. Early detection is vital for improving patient outcomes. Recently, circular RNAs (circRNAs) have emerged as crucial players in the development and progression of various cancers, including GC.

AIM

This comprehensive review underscores the promising potential of circRNAs as innovative biomarkers for the early diagnosis of GC, as well as their possible utility as therapeutic targets for this life-threatening disease. Specifically, the review focuses on recent findings, mechanistic insights, and clinical applications of circRNAs in GC.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Dysregulation of circRNAs has been consistently observed in GC tissues, offering potential diagnostic value due to their stability in bodily fluids such as blood and urine. For instance, circPTPN22 and hsa_circ_000200. Furthermore, the expression levels of circRNAs such as circCUL2, hsa_circ_0000705 and circSHKBP1 have shown strong associations with critical clinical features of GC, including diagnosis, prognosis, tumor size, lymph node metastasis, tumor-node-metastasis (TNM) stage, and treatment response. Additionally, circRNAs such as circBGN, circLMO7, and circMAP7D1 have shown interactions with specific microRNAs (miRNAs), proteins, and other molecules that play key roles in development and progression of GC. This further highlighting their potential as therapeutic targets. Despite their potential, several challenges need to be addressed to effectively apply circRNAs as GC biomarkers. These include standardizing detection methods, establishing cutoff values for diagnostic accuracy, and validating findings in larger patient cohorts. Moreover, the functional mechanisms by which circRNAs contribute to GC pathogenesis and therapeutic resistance warrant further investigation. Advances in circRNAs research could provide valuable insights into the early detection and targeted treatment of GC, ultimately improving patient outcomes.

Circular RNA LDLRAD3 promotes gastric cancer progression by upregulating COL4A5 through sponging miR-h37

BACKGROUND

Circular RNAs play an important role in the development of gastric cancer (GC). circ-low-density lipoprotein receptor class A domain containing 3 (LDLRAD3) has been confirmed to be related to GC progression. miR-137 is also a suppressor in GC. However, the impact of the interaction between circ-LDLRAD3 and miR-137 on the progression of GC remains unclear at present.

METHODS

The study identified expression level differences of circ-LDLRAD3, miR-137, and COL4A5 in GC pathological specimens compared to normal tissue samples. Furthermore, through in vitro experiments, including flow cytometry, cell counting kit-8 (CCK-8) assays, wound healing, Western blotting, and colony formation assays, we further explored the molecular regulatory mechanisms by which these factors promote the progression of GC.

RESULTS

In this study, circ-LDLRAD3 was confirmed to have higher expression, and miR-137 had lower expression in GC tissues and cell lines. circ-LDLRAD3 knockdown and miR-137 overexpression promoted apoptosis and inhibited proliferation, migration, and invasion in GC cell lines. Further experiments validated that COL4A5 had a positive relationship with GC and that circ-LDLRAD3 promoted the expression of COL4A5. circ-LDLRAD3 could be sponged and inhibited by miR-137 in GC cells. As a result, the promotional effect of circ-LDLRAD3 on COL4A5 was counteracted by miR-137.

CONCLUSION

Our study showed that the knockdown of circ-LDLRAD3 suppressed the development of GC by regulating the miR-137/COL4A5 axis.

Comprehensive circular RNA profiling in various sheep tissues

Despite the scientific relevance of circular RNAs (circRNAs), the study of these RNAs in non-model organisms, especially in sheep, is still in its infancy. On the other hand, while some studies have focused on sheep circRNA identification in a limited number of tissues, there is a lack of comprehensive analysis that profile circRNA expression patterns across the tissues not yet investigated. In this study, 61 public RNA sequencing datasets from 12 different tissues were uniformly analyzed to identify circRNAs, profile their expression and investigate their various characteristics. We reported for the first time a circRNA expression landscape with functional annotation in sheep tissues not yet investigated including hippocampus, BonMarrowMacrophage, left-ventricle, thymus, ileum, reticulum and 23-day-embryo. A stringent computational pipeline was employed and 8919 exon-derived circRNAs with high confidence were identified, including 88 novel circRNAs. Tissue-specificity analysis revealed that 3059 circRNAs were tissue-specific, which were also more specific to the tissues than linear RNAs. The highest number of tissue-specific circRNAs was found in kidney, hippocampus and thymus, respectively. Co-expression analysis revealed that expression of circRNAs may not be affected by their host genes. While most of the host genes produced more than one isoform, only one isoform had dominant expression across the tissues. The host genes of the tissue-specific circRNAs were significantly enriched in biological/pathways terms linked to the important functions of their corresponding tissues, suggesting potential roles of circRNAs in modulating physiological activity of those tissues. Interestingly, functional terms related to the regulation and various signaling pathways were significantly enriched in all tissues, suggesting some common regulatory mechanisms of circRNAs to modulate the physiological functions of tissues. Finding of the present study provide a valuable resource for depicting the complexity of circRNAs expression across tissues of sheep, which can be useful for the field of sheep genomic and veterinary research.

CircTSN promotes the proliferation and metastasis of gastric cancer through the miR-1825/SLC38A2 signaling axis

BACKGROUND

Comprehensive treatment of gastric cancer (GC) is progressing, but the rapid proliferation and metastasis of GC remains a cause of high recurrence and mortality rates. In this study we investigated GC-associated circRNA tending to yield more insight into the mechanisms of gastric cancer development.

METHODS

We detected the expression levels of circTSN in GC tissues and cell lines using qRT-PCR. The circular structure of circTSN was confirmed by Sanger sequencing, agarose gel electrophoresis and RNase R. A series of cell functional experiments were employed to investigate the implication of circTSN aberrant expression on the proliferation and metastasis of GC cells. The predicted binding domain between circTSN and miR-1825 was analyzed by luciferase reporter gene analysis. Meanwhile, subcutaneous tumor xenografts in nude mice were used to validate the role of circTSN in vivo.

RESULTS

It was found that RNA levels of circTSN were significantly elevated in GC tissues and cell lines, which was also confirmed to contain a closed-loop structure. CCK8, clone formation, EdU, transwell and in vivo experiments indicated that the highly expressed circTSN was involved in the proliferation and metastasis process of GC. In addition, circTSN modulates the expression of SLC38A2 by sequence-specific binding to miR-1825.

CONCLUSION

This study identified that circTSN, which is highly expressed in GC, was able to contribute to the proliferation and metastasis of GC cell through miR-1825/SLC38A2 axis and this might provide a new candidate target for the precision treatment of GC.

Circ_0008035 Promotes Gastric Cancer Development via the miR-429/SMAD2 Cascade

The vital roles of circular RNAs (circRNAs) in human tumorigenesis have attracted more attention. Circ_0008035 is one of the most up-regulated circRNAs in gastric cancer (GC). Herein, we explored the associated mechanism of circ_0008035 in GC. EdU incorporation experiments were performed to monitor cell proliferation ability. Cell cycle progression, apoptosis, angiogenesis, migration, and invasion were analyzed using flow cytometry, Tube formation, and Transwell assays respectively. Protein expression was detected by Western blot. Dual-luciferase reporter experiments were applied to demonstrate the relationship between circ_0008035 or SMAD family member 2 (SMAD2) and microRNA-429 (miR-429). Mouse xenograft assays were conducted for evaluation of the role of circ_0008035 in vivo. Circ_0008035 content was elevated in GC tissues (P < .0001) and cell lines (P < .001), and its deficiency hindered GC cell proliferation (P < .01), HUVEC angiogenesis (P < .05), and GC cell metastasis (P < .01) and triggered apoptosis (P < .01). Circ_0008035 could sponge miR-429 to up-regulate SMAD2 expression (P < .0001). Circ_0008035 absence restrained tumor growth in vivo (P < .01). MiR429 was a mediator of circ_0008035 function, and miR-429 hindered GC cell malignant phenotypes by SMAD2. Circ_0008035 aggravates GC cell malignant progression partially by targeting the miR-429/SMAD2 axis. Considering the inhibitory effect of circ_0008035 deficiency on GC progression, targeting circ_0008035 may be a potential approach to prevent or treat GC.

MicroRNAs in diabetic macroangiopathy

Diabetic macroangiopathy is a leading cause of diabetes-related mortality worldwide. Both genetic and environmental factors, through a multitude of underlying molecular mechanisms, contribute to the pathogenesis of diabetic macroangiopathy. MicroRNAs (miRNAs), a class of non-coding RNAs known for their functional diversity and expression specificity, are increasingly recognized for their roles in the initiation and progression of diabetes and diabetic macroangiopathy. In this review, we will describe the biogenesis of miRNAs, and summarize their functions in diabetic macroangiopathy, including atherosclerosis, peripheral artery disease, coronary artery disease, and cerebrovascular disease, which are anticipated to provide new insights into future perspectives of miRNAs in basic, translational and clinical research, ultimately advancing the diagnosis, prevention, and treatment of diabetic macroangiopathy.

Circ_0084653 promotes the tumor progression and immune escape in triple-negative breast cancer via the deubiquitination of MYC and upregulation of SOX5

The role of circular RNAs (circRNAs) in cancers is gaining more and more attention, yet related reporters are limited. In triple-negative breast cancer (TNBC), circRNA circ_0084653 originated from COP9 signalosome subunit 5 (COPS5), and COPS5 has been validated to be upregulated in breast cancer before. In our research, COPS5 was also upregulated in TNBC cells, and knockdown of it repressed cell proliferation, invasion, EMT, stemness and PDL-1 protein expression but increased T-cell percentage. Further, circ_0084653 was an aberrantly upregulated circRNA in TNBC cells, and similarly, circ_0084653 silence inhibited TNBC development. Besides, circ_0084653 expression was distributed in both cytoplasm and nucleus. COPS5 overexpression partially rescued the suppressing effects of circ_0084653 depletion in TNBC. Subsequently, circ_0084653 triggered deubiquitination of MYC, the upstream transcription factor of COPS5, via recruiting ubiquitin specific peptidase 36 (USP36). Moreover, circ_0084653 served as the sponge of miR-1323 to release the expression the target gene SRY-box transcription factor 5 (SOX5). SOX5 upregulation completely remedied the inhibiting influence of circ_0084653 downregulation in TNBC. Meanwhile, transcription factor SOX5 activated transcriptionally circ_0084653. To sum up, SOX5-induced circ_0084653 promotes TNBC via the deubiquitination of USP36, which may provide some fresh ideas for TNBC-related molecular mechanisms.

Circ_0001947 encapsulated by small extracellular vesicles promotes gastric cancer progression and anti-PD-1 resistance by modulating CD8+ T cell exhaustion

BACKGROUND

While small extracellular vesicles (sEVs)-derived circular RNAs (circRNAs) have been emerged as significant players in cancer, the function and underlying mechanism of sEVs-derived circRNAs in anti-cancer immunity remain unclear.

METHODS

Gastric cancer (GC)-derived circRNAs were identified using RNA-seq data from GEO datasets and quantitative reverse transcription polymerase chain reaction (qRT-PCR), RNA immunoprecipitation, dual-luciferase assay, and bioinformatics analysis were performed to investigate the regulatory axis. Transwell assay, wound healing assay, cell counting kit-8 (CCK-8) assay, and xenograft models were used to evaluate its role in GC progression in vivo and in vitro. The delivery of specific circRNAs into sEVs were verified through electron microscopy, nanoparticle tracking analysis (NTA) and fuorescence in situ hybridization (FISH). Flow cytometric analysis and immunohistochemical staining were conducted to find out how specific circRNAs mediated CD8+ T cell exhaustion and resistant to anti-programmed cell death 1 (PD-1) therapy.

RESULTS

We identified that circ_0001947, packaged by GC-derived sEVs, was obviously elevated in GC and was associated with poor clinical outcome. High circ0001947 level augmented the proliferation, migration, and invasion of GC cells. Mechanistically, circ0001947 sponged miR-661 and miR-671-5p to promote the expression of CD39, which further facilitated CD8+ T cell exhaustion and immune resistance. Conversely, blocking circ_0001947 attenuated CD8+ T cell exhaustion and increased the response to anti-PD-1 therapy.

CONCLUSIONS

Our study manifested the therapeutic potential of targeting sEVs-transmitted circ_0001947 to prohibit CD8+ T cell exhaustion and immune resistance in GC.

Unraveling the crosstalk: circRNAs and the wnt signaling pathway in cancers of the digestive system

Circular RNA (circRNA) is a unique type of noncoding RNA molecule characterized by its closed-loop structure. Functionally versatile, circRNAs play pivotal roles in gene expression regulation, protein activity modulation, and participation in cell signaling processes. In the context of cancers of the digestive system, the Wnt signaling pathway holds particular significance. Anomalous activation of the Wnt pathway serves as a primary catalyst for the development of colorectal cancer. Extensive research underscores the notable participation of circRNAs associated with the Wnt pathway in the progression of digestive system tumors. These circRNAs exhibit pronounced dysregulation across esophageal cancer, gastric cancer, liver cancer, colorectal cancer, pancreatic cancer, and cholangiocarcinoma. Furthermore, the altered expression of circRNAs linked to the Wnt pathway correlates with prognostic factors in digestive system tumors. Additionally, circRNAs related to the Wnt pathway showcase potential as diagnostic, therapeutic, and prognostic markers within the realm of digestive system tumors. This comprehensive review outlines the interplay between circRNAs and the Wnt signaling pathway in cancers of the digestive system. It seeks to provide a comprehensive perspective on their association while delving into ongoing research that explores the clinical applications of circRNAs associated with the Wnt pathway.

Circ_0004771 regulates malignant biological behaviors and has clinical significance in oral squamous cell carcinoma

BACKGROUND

The incidence of oral squamous cell carcinoma (OSCC) is increasing, and more effective treatment protocols must rapidly be developed to prevent the death of patients and ensure favorable outcomes. CircRNAs are a unique class of noncoding ribonucleic acid (RNA) molecules unaffected by RNA exonucleases. CircRNAs have more stable expression than linear RNAs and are not readily degraded; therefore, they are the newest focus of RNA research. Here, we analyze the mechanism of hsa_circ_0004771 (circ_0004771) in OSCC to provide a clinical reference.

METHODS

Circ_0004771 expression was measured in peripheral blood, cancerous tissues and adjacent tissues of OSCC patients. Patients were followed up for 3 years. The diagnostic value of circ_0004771 for OSCC occurrence, prognosis, recurrence and survival was analyzed with receiver operating characteristic (ROC) curves. OSCC cells were lentivirally transduced with a circ_0004771-silencing or an empty vector to evaluate alterations in cell growth, invasion, and apoptosis. Apoptosis-related and epithelial-mesenchymal transition (EMT)-related protein expression was quantified. BALB/c nude mice were used for tumorigenesis experiments to evaluate tumor growth in vivo after silencing circ_0004771.

RESULTS

Circ_0004771 expression was higher in peripheral blood and cancerous tissue of OSCC patients than in control peripheral blood and paracancerous tissue, respectively, exhibiting excellent predictive value for OSCC occurrence, prognosis, recurrence and survival. Silencing circ_0004771 decreased the growth, invasiveness, and EMT capacity and increased the apoptosis of OCC cells. In mice implanted with OSCC cells transduced with the circ_0004771-silencing lentiviral vector, the tumor growth capacity was obviously decreased.

CONCLUSION

Silencing circ_0004771 inhibits the malignant growth of OSCC.

Exploring the impact of circRNAs on cancer glycolysis: Insights into tumor progression and therapeutic strategies

Cancer cells exhibit altered metabolic pathways, prominently featuring enhanced glycolytic activity to sustain their rapid growth and proliferation. Dysregulation of glycolysis is a well-established hallmark of cancer and contributes to tumor progression and resistance to therapy. Increased glycolysis supplies the energy necessary for increased proliferation and creates an acidic milieu, which in turn encourages tumor cells' infiltration, metastasis, and chemoresistance. Circular RNAs (circRNAs) have emerged as pivotal players in diverse biological processes, including cancer development and metabolic reprogramming. The interplay between circRNAs and glycolysis is explored, illuminating how circRNAs regulate key glycolysis-associated genes and enzymes, thereby influencing tumor metabolic profiles. In this overview, we highlight the mechanisms by which circRNAs regulate glycolytic enzymes and modulate glycolysis. In addition, we discuss the clinical implications of dysregulated circRNAs in cancer glycolysis, including their potential use as diagnostic and prognostic biomarkers. All in all, in this overview, we provide the most recent findings on how circRNAs operate at the molecular level to control glycolysis in various types of cancer, including hepatocellular carcinoma (HCC), prostate cancer (PCa), colorectal cancer (CRC), cervical cancer (CC), glioma, non-small cell lung cancer (NSCLC), breast cancer, and gastric cancer (GC). In conclusion, this review provides a comprehensive overview of the significance of circRNAs in cancer glycolysis, shedding light on their intricate roles in tumor development and presenting innovative therapeutic avenues.

CircCCL22 Regulates CDC25A via Sponging miR-543 and Promotes Proliferation and Metastasis in Endometrial Cancer

Endometrial cancer (EC) is the most common gynecological tumor. Circular RNAs are a novel type of non-coding RNA that have important regulatory functions, particularly in the pathogenic progression of cancer. In this study, we investigated the function of circCCL22, and elucidated its molecular mechanism in EC progresssion. The expression of circCCL22, miR-543 and CDC25A in EC tissues and cells were determined by qRT-PCR and western blot. Cell counting kit-8, 5-ethynyl-2'-deoxyuridine, wound healing and transwell assays were executed to assess the cell viability, proliferation, migration and invasion. Dual-luciferase report assay was utilized to investigate the interaction of miR-543 with circCCL22 and CDC25A. The role of circCCL22 in EC in vivo was investigated by xenograft assay. CircCCL22 was notably upregulated in EC tissues and cells. Functionally, circCCL22 knockdown suppressed EC cell proliferation, migration and invasion in vitro, and inhibited tumor growth in vivo. Mechanistically, circCCL22 acted as "miR-543 sponges" to regulate its targeted gene CDC25A expression in EC cells. The inhibiting effect induced by circCCL22 knockdown on EC cell proliferation, migration and invasion was greatly reversed by miR-543 inhibition or CDC25A overexpression. Our results revealed that circCCL22 regulated EC progression through targeting miR-543/CDC25A axis, and it could be a novel therapeutic target of EC.

Circular RNAs in tumor immunity and immunotherapy

Circular RNAs (circRNAs) are unique noncoding RNAs that have a closed and stable loop structure generated through backsplicing. Due to their conservation, stability and tissue specificity, circRNAs can potentially be used as diagnostic indicators and therapeutic targets for certain tumors. Many studies have shown that circRNAs can act as microRNA (miRNA) sponges, and engage in interactions with proteins and translation templates to regulate gene expression and signal transduction, thereby participating in the occurrence and development of a variety of malignant tumors. Immunotherapy has revolutionized the treatment of cancer. Early researches have indicated that circRNAs are involved in regulating tumor immune microenvironment and antitumor immunity. CircRNAs may have the potential to be important targets for increasing sensitivity to immunotherapy and expanding the population of patients who benefit from cancer immunotherapy. However, few studies have investigated the correlation between circRNAs and tumor immunity. In this review, we summarize the current researches on circRNAs involved in antitumor immune regulation through different mechanisms and their potential value in increasing immunotherapy efficacy with the goal of providing new targets for cancer immunotherapy.

CircRNA as an Achilles heel of cancer: characterization, biomarker and therapeutic modalities

Circular RNAs (circRNAs) are a class of endogenous noncoding RNAs characterized by their lack of 5' caps and 3' poly(A) tails. These molecules have garnered substantial attention from the scientific community. A wide range of circRNA types has been found to be expressed in various tissues of the human body, exhibiting unique characteristics such as high abundance, remarkable stability, and tissue-specific expression patterns. These attributes, along with their detectability in liquid biopsy samples such as plasma, position circRNAs an ideal choice as cancer diagnostic and prognostic biomarkers. Additionally, several studies have reported that the functions of circRNAs are associated with tumor proliferation, metastasis, and drug resistance. They achieve this through various mechanisms, including modulation of parental gene expression, regulation of gene transcription, acting as microRNA (miRNA) sponges, and encoding functional proteins. In recent years, a large number of studies have focused on synthesizing circRNAs in vitro and delivering them to tumor tissue to exert its effects in inhibit tumor progression. Herein, we briefly discuss the biogenesis, characteristics, functions, and detection of circRNAs, emphasizing their clinical potential as biomarkers for cancer diagnosis and prognosis. We also provide an overview the recent techniques for synthesizing circRNAs and delivery strategies, and outline the application of engineered circRNAs in clinical cancer therapy.

Circular RNA ACVR2A promotes the progression of hepatocellular carcinoma through mir-511-5p targeting PI3K-Akt signaling pathway

Circular RNA (circRNA) is thought to mediate the occurrence and development of human cancer and usually acts as a tiny RNA (miRNA) sponge to regulate downstream gene expression. However, it is not clear whether and how circACVR2A (hsa_circ_0001073) is involved in the progression of HCC. The purpose of this study is to clarify the potential role and molecular mechanism of circACVR2A in regulating the progression of hepatocellular carcinoma cells (HCC). The abundance of related proteins in circACVR2A, microRNA (miR511-5p) and PI3K-Akt signaling pathway was determined by quantitative reverse transcriptase polymerase chain reaction (RT-PCR) or Western blotting. Cell viability, invasion and apoptosis were analyzed by CCK-8, Transwell analysis and Tunel staining, respectively. The interaction between circACVR2A and microRNA was evaluated by double luciferase reporter gene assay. The results showed that circACVR2A was highly expressed in hepatocellular carcinoma cell lines. Our in vivo and in vitro data showed that circACVR2A promoted the proliferation, migration and invasion of HCC. In terms of mechanism, we found that circACVR2A can directly interact with miR511-5p and act as a miRNA sponge to regulate the expression of related proteins in PI3K-Akt signaling pathway.In HCC, circACVR2A can mediate miR-511-5p/mRNA network to activate PI3K signal pathway. This shows that the molecular regulatory network with circACVR2A as the core is a new potential target for diagnosis and treatment of hepatocellular carcinoma.

M6A-methylated circPOLR2B forms an R-loop and regulates the biological behavior of glioma stem cells through positive feedback loops

Glioma is the most common primary brain tumor, and targeting glioma stem cells (GSCs) has become a key aspect of glioma treatment. In this study, we discovered a molecular network in which circRNA forms an R-loop structure with its parental gene to regulate the biological behavior of GSCs. Genes with abnormal expression in GSCs were screened using RNA-seq and circRNA microarray analyses. The study results showed that high expression of YTHDC1 in GSCs promoted the transportation of N6-methyladenosine (m6A)-modified circPOLR2B from the nucleus to the cytoplasm. Decreased circPOLR2B levels in the nucleus resulted in fewer R-loop structures formed with its parental gene POLR2B. This reduction in R-loop structures relieved the inhibitory effect on POLR2B transcription and upregulated PBX1 expression through alternative polyadenylation (APA) action, thereby promoting the malignant biological behavior of GSCs. Knockdown of YTHDC1, POLR2B, and PBX1 reduced xenograft tumor volume and prolonged the survival of nude mice. The YTHDC1/circPOLR2B/POLR2B/PBX1 axis plays a regulatory role in the biological behavior of GSCs, offering potential targets and novel strategies for the treatment of glioma.

Hsa_circ_0064636 regulates voltage dependent anion channel 1/ubiquitination factor E4A through miR‑326/miR‑503‑5 in osteosarcoma

Circular RNAs (circRNAs) are a subclass of non-coding RNAs that are important for the regulation of gene expression in eukaryotic organisms. CircRNAs exert various regulatory roles in cancer progression. However, the role of hsa_circ_0064636 in osteosarcoma (OS) remains poorly understood. In the present study, the expression of hsa_circ_0064636 in OS cell lines was measured by reverse transcription-quantitative PCR (RT-qPCR). Differentially expressed mRNAs and microRNAs (miRNA or miRs) were screened using mRNA(GSE16088) and miRNA(GSE65071) expression datasets for OS. miRNAs that can potentially interact with hsa_circ_0064636 were predicted using RNAhybrid, TargetScan and miRanda. Subsequently, RNAhybrid, TargetScan, miRanda, miRWalk, miRMap and miRNAMap were used for target gene prediction based on the overlapping miRNAs to construct a circ/miRNA/mRNA interaction network. Target genes were subjected to survival analysis using PROGgeneV2, resulting in a circRNA/miRNA/mRNA interaction sub-network with prognostic significance. miRNA and circRNA in the subnetwork may also have survival significance, but relevant data are lacking and needs to be further proved. RT-qPCR demonstrated that hsa_circ_0064636 expression was significantly increased in OS cell lines. miR-326 and miR-503-5p were identified to be target miRNAs of hsa_circ_0064636. Among the target genes obtained from the miR-326 and miR-503-5p screens, ubiquitination factor E4A (UBE4A) and voltage dependent anion channel 1 (VDAC1) were respectively identified to significantly affect prognosis; only miR-326 targets UBE4A and only miR-503 targets VDAC1. To conclude, these aforementioned findings suggest that hsa_circ_0064636 may be involved in the development of OS by sponging miR-503-5p and miR-326to inhibit their effects, thereby regulating the expression of VDAC1 and UBE4A.

Mechanistic insights into circRNA-mediated regulation of PI3K signaling pathway in glioma progression

Circular RNAs (CircRNAs) are non-coding RNAs (ncRNAs) characterized by a stable circular structure that regulates gene expression at both transcriptional and post-transcriptional levels. They play diverse roles, including protein interactions, DNA methylation modification, protein-coding potential, pseudogene creation, and miRNA sponging, all of which influence various physiological processes. CircRNAs are often highly expressed in brain tissues, and their levels vary with neural development, suggesting their significance in nervous system diseases such as gliomas. Research has shown that circRNA expression related to the PI3K pathway correlates with various clinical features of gliomas. There is an interact between circRNAs and the PI3K pathway to regulate glioma cell processes such as proliferation, differentiation, apoptosis, inflammation, angiogenesis, and treatment resistance. Additionally, PI3K pathway-associated circRNAs hold potential as biomarkers for cancer diagnosis, prognosis, and treatment. In this study, we reviewed the latest advances in the expression and cellular roles of PI3K-mediated circRNAs and their connections to glioma carcinogenesis and progression. We also highlighted the significance of circRNAs as diagnostic and prognostic biomarkers and therapeutic targets in glioma.

CircRNAs: A promising target for intervention regarding glycolysis in gastric cancer

Gastric cancer is characterized by a high incidence and mortality rate, with therapeutic efficacy currently constrained by substantial limitations. Aerobic glycolysis in cancer constitutes a pivotal aspect of the reprogramming of energy metabolism in tumor cells and profoundly influences the malignant progression of cancer. CircRNAs, serving as stable endogenous RNA, have been shown to regulate downstream targets by sponging miRNAs, which in turn are involved in the regulation of multiple malignant behaviors in a variety of cancers through the CircRNA-miRNA axis, suggesting that CircRNAs could be used as potential therapeutic targets for cancer. In recent years, it has been shown that some CircRNAs can be involved in the regulation of GC glycolysis, therefore, this paper summarizes the notable roles of some important CircRNAs in the regulation of GC glycolysis in recent years, which may be useful for our understanding of GC progression and the development of new therapeutic strategies.

Diagnostic value of plasma circular RNA based on droplet digital polymerase chain reaction in lung adenocarcinoma

BACKGROUND

Plasma circular (circ)RNAs detected by droplet digital polymerase chain reaction (ddPCR) may be ideal markers for liquid biopsy. However, ddPCR detection of circRNAs in plasma for diagnosis of lung adenocarcinoma has been rarely reported.

METHODS

An RNA sequencing analysis was performed in plasma from patients with early lung adenocarcinoma and healthy individuals. Droplet digital PCR was used to verify the differentially expressed genes.

RESULTS

The copy numbers of circle RNALZIC (circLZIC)and circle RNACEP350 (circCEP350) in the plasma of lung adenocarcinoma patients were significantly higher than in plasma of healthy people, and the copy numbers in postoperative plasma of the same patients were significantly lower than those in preoperative plasma. CircLZIC and circCEP350 alone and in combination had diagnostic value in lung adenocarcinoma and early lung adenocarcinoma. CircLZIC and circCEP350 had more binding sites with multiple microRNAs. Their target genes were enriched in several signaling pathways.

CONCLUSION

The copy numbers of circLZIC and circCEP350 were higher in plasma of lung adenocarcinoma patients than in plasma of healthy controls, significantly correlated with tumor size and TNM stage, and closely related to the occurrence and development of tumors. These circRNAs may serve as molecular markers for the diagnosis of lung adenocarcinoma.

Decreasing circ_0014614 promotes the differentiation of bone marrow flineage cells into megakaryocytes in essential thrombocythemia via activiation of miR-138-5p/caspase3 axis

BACKGROUND

Circular RNAs (circRNA) are pivotal in hematological diseases. Previous study showed that circ_0014614 (circDAP3) was significantly underexpressed in bone marrow-derived exosomes from essential thrombocythemia (ET) patients, affecting the differentiation of bone marrow lineage cells into megakaryocytes.

METHODS

Fluorescence in situ hybridization (FISH) was used to display circ_0014614's primary cytoplasmic location in K562 cells. Cytoscape software was used to predict the circRNA-miRNA-mRNA networks, and their expression at the cellular level was detected by Quantitative reverse transcription-polymerase chain reaction (qRT-PCR). qRT-PCR was utilized to detect the expression levels of circ_0014614，miR-138-5p and caspase3 mRNA. Western blot was used to determine the protein levels of GATA-1, RUNX-1, NF-E2, CD41 and caspase3. The proliferation of K562 cells was assessed using the Cell Counting Kit-8 (CCK-8) Assay. Furthermore, the interplay between miR-138-5p and circ_0014614 or caspase3 was elucidated through a Dual-luciferase reporter assay.

RESULTS

FISH assay indicated circ_0014614's primary cytoplasmic location in K562 cells. In ET bone marrow and K562 cells, circ_0014614 and caspase3 were down-regulated, whereas miR-138-5p saw a significant surge. Overexpressing circ_0014614 curtailed K562 cells' proliferation and differentiation. Further, circ_0014614 targeted miR-138-5p, with heightened miR-138-5p levels counteracting circ_0014614's inhibition. MiR-138-5p further targeted caspase3, and caspase3 silencing neutralized suppressed miR-138-5p's effects on K562 cell differentiation.

CONCLUSION

Circ_0014614 was down-regulated in ET bone marrow and bone marrow lineage cells, and upregulating circ_0014614 can inhibit bone marrow lineage cells' proliferation and differentiation into megakaryocytes. Mechanistically, circ_0014614 functioned as ceRNA via sponging miR-138-5p and alleviated the inhibitory effect of miR-138-5p on its target caspase3, which potentially deters tumor activity in ET.

CircSLC25A16 facilitates the development of non-small-cell lung cancer through the miR-335-5p/CISD2 axis

BACKGROUND

Non-small-cell lung cancer (NSCLC) is a common malignancy with high morbidity and mortality. Circular RNAs are widely involved in NSCLC progression. However, the mechanism of circSLC25A16 in NSCLC has not been reported.

METHODS

The expressions of circSLC25A16, microRNA-335-5p (miR-335-5p), and CDGSH iron-sulfur domain-containing protein 2 (CISD2) were monitored by quantitative real-time fluorescence polymerase chain reaction. Western blot was also carried out to measure the protein levels of CISD2, hexokinase 2 (HK2), and lactate dehydrogenase A (LDHA). For functional analysis, cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine, flow cytometry, transwell, and wound healing assays were utilized to examine cell proliferation, apoptosis, and migration. Glucose uptake and lactate production were detected using commercial kits. The relationship between miR-335-5p and circSLC25A16 or CISD2 was verified by dual-luciferase reporter and RNA immunoprecipitation assays. Furthermore, tumor xenograft was established to explore the function of circSLC25A16 in vivo.

RESULTS

CircSLC25A16 and CISD2 were overexpressed in NSCLC, but miR-335-5p was downregulated. CircSLC25A16 acted as a miR-335-5p sponge, and silencing of circSLC25A16 arrested cell proliferation, migration, and glycolysis, and promoted apoptosis, but these impacts were resumed by miR-335-5p inhibition. CISD2 was a miR-335-5p target, and overexpression of CISD2 abolished the suppressive function of miR-335-5p mimic on the malignant behavior of NSCLC cells. CircSLC25A16 could adsorb miR-335-5p to mediate CISD2 expression. Additionally, silencing circSLC25A16 restrained the growth of NSCLC tumor xenograft in vivo.

CONCLUSION

CircSLC25A16 facilitated NSCLC progression via the miR-335-5p/CISD2 axis, implying that circSLC25A16 may serve as a novel biomarker for NSCLC treatment.

Extracellular vesicle-delivered hsa_circ_0090081 regulated by EIF4A3 enhances gastric cancer tumorigenesis

BACKGROUND

Circular RNA (circRNA) and extracellular vesicles (EVs) in tumors are crucial for the malignant phenotype of tumor cells. Nevertheless, the mechanisms and clinical effects of EV-delivered hsa_circ_0090081 in gastric cancer (GC) are unclear. This study aimed to reveal the effect of eukaryotic translation initiation factor 4A3 (EIF4A3)-mediated hsa_circ_0090081 expression and EV-delivered hsa_circ_0090081 on GC progression.

METHODS

qRT-PCR was conducted to clarify hsa_circ_0090081 and EIF4A3 levels in GC tissues. Transmission electronic microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blotting identified the EVs isolated from GC cells by ultracentrifugation. The roles of hsa_circ_0090081, EIF4A3, and EV-delivered hsa_circ_0090081 in GC cells were analyzed using Transwell, EdU, and CCK-8 assays. The regulatory role between EIF4A3 and hsa_circ_0090081 was investigated using RIP, qRT-PCR, and Pearson's analysis.

RESULTS

Our study showed that hsa_circ_0090081 and EIF4A3 were highly expressed in GC, and hsa_circ_0090081 was associated with poor prognosis. Data revealed that hsa_circ_0090081 inhibition restrained GC cell proliferation, invasion, and migration. Additionally, EIF4A3 could bind to the pre-mRNA of PHEX (linear form of hsa_circ_0090081) to enhance hsa_circ_0090081 expression in GC cells. Moreover, EIF4A3 overexpression nullified the malignant phenotypic suppression caused by hsa_circ_0090081 silencing in GC cells. Furthermore, EVs secreted by GC cells delivered hsa_circ_0090081 to facilitate the malignant progression of targeted GC cells.

CONCLUSION

This study showed that hsa_circ_0090081 was enhanced by EIF4A3 to play a promotive role in GC development. The results may help understand the mechanism of EIF4A3 and EV-delivered hsa_circ_0090081 and offer a valuable GC therapeutic target.

Non‑coding RNA: A promising diagnostic biomarker and therapeutic target for esophageal squamous cell carcinoma (Review)

Esophageal cancer (EC) is a common form of malignant tumor in the digestive system that is classified into two types: Esophageal squamous cell carcinomas (ESCC) and esophageal adenocarcinoma. ESCC is known for its early onset of symptoms, which can be difficult to identify, as well as its rapid progression and tendency to develop drug resistance to chemotherapy and radiotherapy. These factors contribute to the high incidence of disease and low cure rate. Therefore, a diagnostic biomarker and therapeutic target need to be identified for ESCC. Non-coding RNAs (ncRNAs) are a class of molecules that are transcribed from DNA but do not encode proteins. Initially, ncRNAs were considered to be non-functional segments generated during transcription. However, with advancements in high-throughput sequencing technologies in recent years, ncRNAs have been associated with poor prognosis, drug resistance and progression of ESCC. The present study provides a comprehensive overview of the biogenesis, characteristics and functions of ncRNAs, particularly focusing on microRNA, long ncRNAs and circular RNAs. Furthermore, the ncRNAs that could potentially be used as diagnostic biomarkers and therapeutic targets for ESCC are summarized to highlight their application value and prospects in ESCC.

A novel protein FNDC3B-267aa encoded by circ0003692 inhibits gastric cancer metastasis via promoting proteasomal degradation of c-Myc

BACKGROUND

Gastric cancer (GC) ranks fifth in global cancer incidence and third in mortality rate among all cancer types. Circular RNAs (circRNAs) have been extensively demonstrated to regulate multiple malignant biological behaviors in GC. Emerging evidence suggests that several circRNAs derived from FNDC3B play pivotal roles in cancer. However, the role of circFNDC3B in GC remains elusive.

METHODS

We initially screened circFNDC3B with translation potential via bioinformatics algorithm prediction. Subsequently, Sanger sequencing, qRT-PCR, RNase R, RNA-FISH and nuclear-cytoplasmic fractionation assays were explored to assess the identification and localization of circ0003692, a circRNA derived from FNDC3B. qRT-PCR and ISH were performed to quantify expression of circ0003692 in human GC tissues and adjacent normal tissues. The protein-encoding ability of circ0003692 was investigated through dual-luciferase reporter assay and LC/MS. The biological behavior of circ0003692 in GC was confirmed via in vivo and in vitro experiments. Additionally, Co-IP and rescue experiments were performed to elucidate the interaction between the encoded protein and c-Myc.

RESULTS

We found that circ0003692 was significantly downregulated in GC tissues. Circ0003692 had the potential to encode a novel protein FNDC3B-267aa, which was downregulated in GC cells. We verified that FNDC3B-267aa, rather than circ0003692, inhibited GC migration in vitro and in vivo. Mechanistically, FNDC3B-267aa directly interacted with c-Myc and promoted proteasomal degradation of c-Myc, resulting in the downregulation of c-Myc-Snail/Slug axis.

CONCLUSIONS

Our study revealed that the novel protein FNDC3B-267aa encoded by circ0003692 suppressed GC metastasis through binding to c-Myc and enhancing proteasome-mediated degradation of c-Myc. The study offers the potential applications of circ0003692 or FNDC3B-267aa as therapeutic targets for GC.

Circular RNA Circ_0000119 promotes gastric cancer progression via circ_0000119/miR-502-5p/MTBP axis

Dysregulated circular RNAs (circRNAs) are significantly related with tumor initiation and progression. However, biological activity and potential molecular mechanism of circRNAs in gastric cancer (GC) deserve further exploration. We carried out total RNA sequencing and acquired the expression profiles of circRNAs. Quantitative real-time PCR as well as RNA in situ hybridization helped to validate circ_0000119 dysregulation. Various in vitro experiments were utilized to investigate the biological activities of circ_0000119 in GC, and the clinical relation of circ_0000119 in vivo was identified through nude mouse xenograft models. Finally, the molecular mechanism of circ_0000119 was clarified via luciferase assays, western blot, and rescue experiments. Compared with adjacent normal tissues, the study found an increase in the expression of circ_0000119 as well as its host linear gene MAN1A2 in GC tissues. Circ_0000119 overexpression promoted proliferation and migration of GC cells in vitro and in vivo, whereas circ_0000119 suppression had the opposite effect. Mechanistically, circ_0000119 sponged miR-502-5p which played an inhibitory role in tumors. Furthermore, we found that miR-502-5p alleviated GC progression through targeting MTBP and downregulating its expression at mRNA and protein levels. In conclusion, our findings reveal a new regulatory mechanism for circ_0000119, which sponges the miR-502-5p, suppresses MTBP expression, and finally promotes GC progression.

Long-term exposure to PM2.5 leads to mitochondrial damage and differential expression of associated circRNA in rat hepatocytes

Fine particulate matter (PM2.5) is one of the four major causes of mortality globally. The objective of this study was to investigate the mechanism underlying liver injury following exposure to PM2.5 and the involvement of circRNA in its regulation. A PM2.5 respiratory tract exposure model was established in SPF SD male rats with a dose of 20 mg/kg, and liver tissue of rats in control group and PM2.5-exposed groups rats were detected. The results of ICP-MS showed that Mn, Cu and Ni were enriched in the liver. HE staining showed significant pathological changes in liver tissues of PM2.5-exposed group, transmission electron microscopy showed significant changes in mitochondrial structure of liver cells, and further mitochondrial function detection showed that the PM2.5 exposure resulted in an increase in cell reactive oxygen species content and a decrease in mitochondrial transmembrane potential, while the expression of SOD1 and HO-1 antioxidant oxidase genes was upregulated. Through high-throughput sequencing of circRNAs, we observed a significant down-regulation of 10 and an up-regulation of 17 circRNAs in the PM2.5-exposed groups. The functional enrichment and pathway analyses indicated that the differentially expressed circRNAs by PM2.5 exposure were primarily associated with processes related to protein ubiquitination, zinc ion binding, peroxisome function, and mitochondrial regulation. These findings suggest that the mechanism underlying liver injury induced by PM2.5-exposure may be associated with mitochondrial impairment resulting from the presence of heavy metal constituents. Therefore, this study provides a novel theoretical foundation for investigating the molecular mechanisms underlying liver injury induced by PM2.5 exposure.

Identification of circRNA Expression Profile and Potential Systemic Immune Imbalance Modulation in Premature Rupture of Membranes

Premature rupture of membrane (PROM) refers to the rupture of membranes before the onset of labor which increases the risk of perinatal morbidity and mortality. Recently, circular RNAs (circRNAs) have emerged as promising regulators of diverse diseases. However, the circRNA expression profiles and potential circRNA-miRNA-mRNA regulatory mechanisms in PROM remain enigmatic. In this study, we displayed the expression profiles of circRNAs and mRNAs in plasma and fetal membranes of PROM and normal control (NC) groups based on circRNA microarray, the Gene Expression Omnibus database, and NCBI's Sequence Read Archive. A total of 1,459 differentially expressed circRNAs (DECs) in PROM were identified, with 406 upregulated and 1,053 downregulated. Then, we constructed the circRNA-miRNA-mRNA network in PROM, encompassing 22 circRNA-miRNA pairs and 128 miRNA-mRNA pairs. Based on the analysis of gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and gene set enrichment analysis (GSEA), DECs were implicated in immune-related pathways, with certain alterations persisting even postpartum. Notably, 11 host genes shared by DECs of fetal membrane tissue and prenatal plasma in PROM were significantly implicated in inflammatory processes and extracellular matrix regulation. Our results suggest that structurally stable circRNAs may predispose to PROM by mediating systemic immune imbalances, including peripheral leukocyte disorganization, local immune imbalance at the maternal-fetal interface, and local collagen disruption. This is the first time to decipher a landscape on circRNAs of PROM, reveals the pathogenic cause of PROM from the perspective of circRNA, and opens up a new direction for the diagnosis and treatment of PROM.

ALKBH5-mediated m6A modification of circFOXP1 promotes gastric cancer progression by regulating SOX4 expression and sponging miR-338-3p

Circular RNAs (circRNAs) have recently been suggested as potential functional modulators of cellular physiology processes in gastric cancer (GC). In this study, we demonstrated that circFOXP1 was more highly expressed in GC tissues. High circFOXP1 expression was positively associated with tumor size, lymph node metastasis, TNM stage, and poor prognosis in patients with GC. Cox multivariate analysis revealed that higher circFOXP1 expression was an independent risk factor for disease-free survival (DFS) and overall survival (OS) in GC patients. Functional studies showed that increased circFOXP1 expression promoted cell proliferation, cell invasion, and cell cycle progression in GC in vitro. In vivo, the knockdown of circFOXP1 inhibited tumor growth. Mechanistically, we observed ALKBH5-mediated m6A modification of circFOXP1 and circFOXP1 promoted GC progression by regulating SOX4 expression and sponging miR-338-3p in GC cells. Thus, our findings highlight that circFOXP1 could serve as a novel diagnostic and prognostic biomarker and potential therapeutic target for GC.

Riddle of the Sphinx: Emerging role of circular RNAs in cervical cancer

Cervical cancer is a prominent cause of cancer-related mortality among women, with recent attention directed toward exploring the involvement of circular RNAs (circRNAs) in this particular cancer. CircRNAs, characterized by a covalently closed loop structure, belong to a class of single-stranded non-coding RNA (ncRNA) molecules that play crucial roles in cancer development and progression through diverse mechanisms. The abnormal expression of circRNAs in vivo is significantly associated with the development of cervical cancer. Notably, circRNAs actively interact with miRNAs in cervical cancer, leading to the regulation of diverse signaling pathways, and they can contribute to cancer hallmarks such as self-sufficiency in growth signals, insensitivity to antigrowth signals, limitless proliferation, evading apoptosis, tissue invasion and metastasis, and sustained angiogenesis. Moreover, the distinctive biomedical attributes exhibited by circRNAs, including their abundance, conservation, and stability in body fluids, position them as promising biomarkers for various cancers. In this review, we elucidate the tremendous potential of circRNAs as diagnostic markers or therapeutic targets in cervical cancer by expounding upon their biogenesis, characteristics, functions, and databases, highlighting the novel advances in the signaling pathways associated with circRNAs in cervical cancer.

Human circular RNA hsa_circ_0000231 clinical diagnostic effectiveness as a new tumor marker in gastric cancer

BACKGROUND

Owing to the subtlety of initial symptoms associated with gastric cancer (GC), the majority of patients are diagnosed at later stages. Given the absence of reliable diagnostic markers, it is imperative to identify novel markers that exhibit high sensitivity and specificity. Circular RNA, a non-coding RNA, plays an important role in tumorigenesis and development and is well expressed in body fluids.

AIMS

In this study, we aimed to identify hsa_circ_0000231 as a new biomarker for the diagnosis of GC and to assess its clinical diagnostic value in serum.

METHODS AND RESULTS

The stability and correctness of hsa_circ_0000231 was determined by agarose gel electrophoresis, Rnase R assay and Sanger sequencing. Real-time quantitative polymerase chain reaction (qRT-PCR) was designed to discover the expression level of hsa_circ_0000231 and whether it has dynamic serum monitoring capability. The correlation between hsa_circ_0000231 and clinicopathological parameters was analyzed by collecting clinical and pathological data from GC patients. In addition, diagnostic efficacy was assessed by constructing receiver operating characteristic curves (ROC). Hsa_circ_0000231 exhibits a stable and consistently expressed structure. In GC serum, cells, and tissues, it demonstrates reduced expression levels. Elevated expression levels observed postoperatively suggest its potential for dynamic monitoring. Additionally its expression level correlates with TNM staging and neuro/vascular differentiation. The area under ROC curve (AUC) for hsa_circ_0000231 is 0.781, indicating its superior diagnostic value compared to CEA, CA19-9, and CA72-4. The combination of these four indicators enhances diagnostic accuracy, with an AUC of 0.833.

CONCLUSIONS

The stable expression of hsa_circ_0000231 in the serum of gastric cancer patients holds promise as a novel biomarker for both the diagnosis and dynamic monitoring of GC.

Hsa_circ_0003356 suppresses gastric cancer progression via miR-556-5p/FKBP5 axis

BACKGROUND

CircRNAs are implicated in the tumorigenesis of various human cancers. This study aims to explore how circ_0003356 contributes to the development of gastric cancer (GC).

METHODS

Circ_0003356 expression was analyzed in GSE184882 dataset and validated in our cohort of GC patients and human GC cell lines. The correlations between circ_0003356 levels and prognostic parameters were analyzed. The contribution of circ_0003356 in GC cell malignant behaviors such as cell survival, apoptosis and invasion were investigated by circ_0003356 overexpression in GC cell lines. The downstream targets of circ_0003356 were predicted and verified in vitro and in vivo. The in vivo function of circ_0003356 was studied as well in a xenograft mouse model.

RESULTS

Circ_0003356 expressed at a low level in human GC tissues and cells, which was closely associated with poor outcome of GC patients. Circ_0003356 overexpression induced GC cell apoptosis while depressed the growing, migration and invasive abilities through miR-556-5p/FKBP5 axis. In vivo model showed retarded tumor growth when circ_0003356-overexpressed cells were inoculated.

CONCLUSION

Circ_0003356 is identified as a potential biomarker of the prognosis of human gastric cancer, and circ_0003356/miR-556-5p/FKBP5 axis could be a promising target in gastric cancer treatment.

Potential therapeutic strategy for cancer: Multi-dimensional cross-talk between circRNAs and parental genes

In many ways, circular RNAs (circRNAs) have been demonstrated to be crucial in the onset and advancement of cancer throughout the last ten years and have become a new focus of intense research in the field of RNAs. Accumulating studies have demonstrated that circRNAs can regulate parental gene expression via a variety of biological pathways. Furthermore, research into the complex interactions between circRNAs and their parental genes will shed light on their biological roles and open up new avenues for circRNAs' potential clinical translational uses. However, to date, multi-dimensional cross-talk between circRNAs and parental genes have not been systematically elucidated. Particularly intriguing is circRNA's exploration of tumor targeting, and potential therapeutic uses based on the parental gene regulation perspective. Here, we discuss their biogenesis, take a fresh look at the molecular mechanisms through which circRNAs control the expression of their parental genes in cancer. We further highlight We further highlight the latest circRNA clinical translational applications, including prognostic diagnostic markers, cancer vaccines, gDNA, and so on. Demonstrating the potential benefits and future applications of circRNA therapy.

CircPRKD3/miR-6783-3p responds to mechanical force to facilitate the osteogenesis of stretched periodontal ligament stem cells

BACKGROUND

The mechanotransduction mechanisms by which cells regulate tissue remodeling are not fully deciphered. Circular RNAs (circRNAs) are crucial to various physiological processes, including cell cycle, differentiation, and polarization. However, the effects of mechanical force on circRNAs and the role of circRNAs in the mechanobiology of differentiation and remodeling in stretched periodontal ligament stem cells (PDLSCs) remain unclear. This article aims to explore the osteogenic function of mechanically sensitive circular RNA protein kinase D3 (circPRKD3) and elucidate its underlying mechanotransduction mechanism.

MATERIALS AND METHODS

PDLSCs were elongated with 8% stretch at 0.5 Hz for 24 h using the Flexcell® FX-6000™ Tension System. CircPRKD3 was knockdown or overexpressed with lentiviral constructs or plasmids. The downstream molecules of circPRKD3 were predicted by bioinformatics analysis. The osteogenic effect of related molecules was evaluated by quantitative real-time PCR (qRT-PCR) and western blot.

RESULTS

Mechanical force enhanced the osteogenesis of PDLSCs and increased the expression of circPRKD3. Knockdown of circPRKD3 hindered PDLSCs from osteogenesis under mechanical force, while overexpression of circPRKD3 promoted the early osteogenesis process of PDLSCs. With bioinformatics analysis and multiple software predictions, we identified hsa-miR-6783-3p could act as the sponge of circPRKD3 to indirectly regulate osteogenic differentiation of mechanically stimulated PDLSCs.

CONCLUSIONS

Our results first suggested that both circPRKD3 and hsa-miR-6783-3p could enhance osteogenesis of stretched PDLSCs. Furthermore, hsa-miR-6783-3p could sponge circPRKD3 to indirectly regulate RUNX2 during the periodontal tissue remodeling process in orthodontic treatment.