Circular RNA CircZNF644 Facilitates Circulating Follicular Helper T Cells Response in Patients with Graves' Disease.

Aberrant accumulation of circulating follicular helper T cells (cTfh) has been found in the peripheral blood mononuclear cells (PBMCs) of Graves' disease (GD) patients. However, the underlying mechanism that contributes to the imbalance of cTfh cells remains unknown. Previously, studies described a GD-related circular RNAs (circRNAs)-circZNF644 that might be associated with cTfh cells. This study aimed to investigate the role of circZNF644 on cTfh cells in GD patients. Here, we found that circZNF644 was highly stable expression in the PBMCs of GD patients, which was positively correlated with the serum levels of TSH receptor autoantibodies (TRAb). Knockdown of circZNF644 caused a reduction of the proportion of cTfh cells in vitro. Mechanistically, circZNF644 served as a ceRNA for miR-29a-3p to promote ICOS expression, resulting in increased cTfh cells. In the PBMCs of GD patients, circZNF644 expression was positively correlated with ICOS expression and the percentage of cTfh cells, but negatively related to miR-29a-3p expression. Additionally, a strong relationship between circZNF644 and IL-21 was revealed in GD patients, and silencing of circZNF644 inhibited IL-21 expression. Our study elucidated that elevated expression of circZNF644 is a key feature in the development of GD and may contribute to the pathogenic role of cTfh cells in GD.

Differential expression profiles and functional prediction of circular RNAs in lung cancer patients with chronic obstructive pulmonary disease: a pilot study.

Chronic obstructive pulmonary disease (COPD), characterized by clinical sub-phenotypes such as emphysema (E) and chronic bronchitis (CB), is associated with a greater risk of lung cancer (LC). This study aimed to assess the expression patterns of circRNA and their potential functional involvement in LC patients with COPD. A circRNA microarray was used to characterize differentially expressed circRNAs (DEcircRNAs) profiles. A total of 176, 240, 163, and 243 DEcircRNAs were identified in comparisons between CB vs. LC patients (Con), E vs. Con, E vs. CB, and CBE vs. Con, respectively. DEcircRNAs in all comparison groups were primarily associated with immune-related GO terms and were also enriched in immune and inflammatory pathways. In total, 49 DEcircRNAs were significantly correlated with the infiltration of multiple immune cells. Among them, hsa-MROH9_0001 and hsa-RP11-35J10_0013 were positively and negatively correlated with plasma cells and T-cell CD4 memory resting cells, respectively; these two DEcircRNA-sponged miRNAs have good diagnostic performance. WGCNA identified six key circRNAs associated with CB progression. The expression patterns of hsa-MROH9_0001 and circRNA_21729 in E and CB groups were confirmed by RT-qPCR. In conclusion, we reported circRNA profiles and the findings demonstrated that hsa-MROH9_0001 and circRNA_21729 may be potential therapeutic targets for LC with COPD.

New challenges in hepatocellular carcinoma: A role for PIWI-interacting RNAs?

Hepatocellular carcinoma (HCC) is the most common and deadliest subtype of liver cancer worldwide and, therefore, poses an enormous threat to global health. Understanding the molecular mechanisms underlying the development and progression of HCC is central to improving our clinical approaches. PIWI-interacting RNAs (piRNAs) are a class of small non-coding RNAs that bind to PIWI family proteins to regulate gene expression at transcriptional and post-transcriptional levels. A growing body of work shows that the dysregulation of piRNAs plays a crucial role in the progression of various human cancers. In this editorial, we report on the current knowledge of HCC-associated piRNAs and their potential clinical utility. Based on the editorial by Papadopoulos and Trifylli, on the role and clinical evaluation of exosomal circular RNAs in HCC, we highlight this other emerging class of non-coding RNAs.

Roles of non-coding RNA in diabetic cardiomyopathy.

In recent years, the incidence of diabetes has been increasing rapidly, posing a serious threat to human health. Diabetic cardiomyopathy (DCM) is characterized by cardiomyocyte hypertrophy, myocardial fibrosis, apoptosis, ventricular remodeling, and cardiac dysfunction in individuals with diabetes, ultimately leading to heart failure and mortality. However, the underlying mechanisms contributing to DCM remain incompletely understood. With advancements in molecular biology technology, accumulating evidence has shown that numerous non-coding RNAs (ncRNAs) crucial roles in the development and progression of DCM. This review aims to summarize recent studies on the involvement of three types of ncRNAs (micro RNA, long ncRNA and circular RNA) in the pathophysiology of DCM, with the goal of providing innovative strategies for the prevention and treatment of DCM.

CircCUL1 inhibits trophoblast cell migration and invasion and promotes cell autophagy by sponging hsa-miR-30e-3p in fetal growth restriction via the ANXA1/PI3K/AKT axis.

Fetal growth restriction (FGR) severely affects the health outcome of newborns and represents a major cause of perinatal morbidity. The precise involvement of circCULT1 in the progression of FGR remains unclear. We performed next-generation sequencing and RT-qPCR to identify differentially expressed circRNAs in placental tissues affected by FGR by comparing them with unaffected counterparts. Edu, flow cytometry, and transwell assay were conducted to detect HTR8/SVneo cell's function in regard to cell proliferation, migration, and invasion. The interaction between circCUL1 and hsa-miR-30e-3p was assessed through dual-luciferase reporter assays, validation of the interaction between circCUL1 and ANXA1 was performed using RNA pulldown and immunoprecipitation assays. Western blot analysis was performed to evaluate protein levels of autophagy markers and components of the PI3K/AKT signaling pathway. A knockout (KO) mouse model was established for homologous mmu-circ-0001469 to assess fetal mouse growth and development indicators. Our findings revealed an upregulation of circCUL1 expression in placental tissues from patients with FGR. We found that suppression of circCUL1 increased the trophoblast cell proliferation, migration, and invasion, circCUL1 could interact with hsa-miR-30e-3p. Further, circCUL1 stimulated autophagy, modulating trophoblast cell autophagy via the ANXA1/PI3K/AKT pathway, and a notable disparity was observed, with KO mice displaying accelerated embryo development and exhibiting heavier placentas in comparison to wild-type C57BL/6 mice. By modulating the ANXA1/PI3K/AKT signaling pathway through the interaction with hsa-miR-30e-3p, circCUL1 promotes autophagy while concurrently suppressing trophoblast cell proliferation, migration, and invasion. These findings offer novel insights into potential diagnostic markers and therapeutic targets for FGR research.

[Progress of research on circular RNA encoding proteins in disease].

With the advance of research, non-coding RNA has been found to surpass the traditional definition to directly code functional proteins by coding sequence elements and binding with ribosomes. Among the non-coding RNAs, the function of circRNA encoded proteins has been most extensively studied. This study has used "circRNA", "encoded", and "translation" as the key words to search the PubMed and Web of Science databases. The retrieved literature was screened and traced, with the translation mechanism, related research methods, and correlation with diseases of circRNA reviewed. CircRNA can translate proteins through a non-cap-dependent pathway. Multiple molecular techniques, in particular mass spectrometry analysis, have important value in identifying unique peptide segments of circRNA encoded proteins for confirming their existence. The proteins encoded by the circRNA are involved in the pathogenesis of diseases of the digestive, neurological, urinary systems and the breast, and have the potential to serve as novel targets for disease diagnosis and treatment. This article has provided a comprehensive review for the basic theory, experimental methods, and disease-related research in the field of circRNA translation, which may provide clues for the identification of new diagnostic and therapeutic targets.

The circular RNA circSLC16A10 alleviates diabetic retinopathy by improving mitochondrial function via the miR-761-5p/MFN2 axis.

It has been demonstrated that circular RNAs (circRNAs) are associated with the development of diabetic retinopathy (DR). Nevertheless, the function of circSLC16A10 in the development of DR remains unclear. In order to investigate the role of circSLC16A10, we employed cell and animal models of DR. An analysis of a public database revealed that hsa_circSLC16A10 was expressed at lower levels in DR patients than in diabetic patients without DR or healthy controls. Additionally, the level of hsa_circSLC16A10 was lower in high glucose (HG)-exposed ARPE-19 cells and diabetic mice. hsa_circSLC16A10 was observed to be mainly distributed in the cytoplasm. Moreover, overexpression of hsa_circSLC16A10 alleviated HG-induced endoplasmic reticulum stress and cell apoptosis in vitro. Furthermore, overexpression of hsa_circSLC16A10 ameliorated HG-induced mitochondrial dysfunction, as evidenced by improvements in mitochondrial structure and function. hsa_circSLC16A10 acted as a hsa-miR-761-5p sponge to increase MFN2 expression. MFN2 knockdown or hsa-miR-761-5p overexpression partially reversed the protective effect of hsa_circSLC16A10 in vitro. The protective effect of mmu_circSLC16A10 against DR was confirmed in an animal model of DR. These findings indicate that circSLC16A10 may regulate DR progression by improving mitochondrial function via the miR-761-5p/MFN2 axis.

Cross-talk between circRNAs and m6A modifications in solid tumors.

Circular RNAs (circRNAs) possess unique biological properties and distribution characteristics that enable a variety of biological functions. N6-methyladenosine (m6A), a prevalent epigenetic modification in organisms, is regulated by factors including methyltransferases (writers), demethylases (erasers), and m6A-binding proteins (readers). These factors play critical roles in various pathophysiological processes. There is growing evidence that m6A modifications are common within circRNAs, affecting their synthesis, translation, translocation, degradation, and stability. Additionally, circRNAs regulate biological processes that influence m6A modifications. This review explores the metabolism and functions of m6A modifications and circRNAs, their interactions, and their specific regulatory mechanisms in different tumors, offering insights into m6A-circRNA interaction in cancer.

Advances in CircRNAs in the Past Decade: Review of CircRNAs Biogenesis, Regulatory Mechanisms, and Functions in Plants.

Circular RNA (circRNA) is a type of non-coding RNA with multiple biological functions. Whole circRNA genomes in plants have been identified, and circRNAs have been demonstrated to be widely present and highly expressed in various plant tissues and organs. CircRNAs are highly stable and conserved in plants, and exhibit tissue specificity and developmental stage specificity. CircRNAs often interact with other biomolecules, such as miRNAs and proteins, thereby regulating gene expression, interfering with gene function, and affecting plant growth and development or response to environmental stress. CircRNAs are less studied in plants than in animals, and their regulatory mechanisms of biogenesis and molecular functions are not fully understood. A variety of circRNAs in plants are involved in regulating growth and development and responding to environmental stress. This review focuses on the biogenesis and regulatory mechanisms of circRNAs, as well as their biological functions during growth, development, and stress responses in plants, including a discussion of plant circRNA research prospects. Understanding the generation and regulatory mechanisms of circRNAs is a challenging but important topic in the field of circRNAs in plants, as it can provide insights into plant life activities and their response mechanisms to biotic or abiotic stresses as well as new strategies for plant molecular breeding and pest control.

Identification and Comprehensive Analysis of circRNA-miRNA-mRNA Regulatory Networks in A2780 Cells Treated with Resveratrol.

Ovarian cancer (OC) is one of the most commonplace gynecological malignancies. This study explored the effects of resveratrol (RES) on OC cell proliferation and apoptosis. Proliferation activity was measured for A2780 cells treated with RES for 24 h and 48 h at concentrations of 0, 10, 25, 50, 75, 100, 150, 200, and 300 µM. RNA sequencing (RNA-seq) was performed to analyze the circular RNA (circRNA), microRNA (miRNA), and messenger RNA (mRNA) expression spectrum. The differentially expressed genes included 460 circRNAs, 1988 miRNAs, and 1671 mRNAs, and they were subjected to analyses including Gene Ontology, the Kyoto Encyclopedia of Genes and Genomes (KEGG), and Reactome enrichment. We selected signaling pathways enriched in the cell processes by mRNA KEGG, comprehensively analyzed the circRNA-miRNA-mRNA regulatory network, and verified several miRNAs expressed in the regulatory network diagram using the quantitative real-time polymerase chain reaction. The data showed that the cell proliferation of A2780 cells treated with RES for 24 h or 48 h decreased with increasing concentrations of RES. The circRNA-miRNA-mRNA regulatory network that we constructed provides new insights into the ability of RES to inhibit cell proliferation and promote apoptosis in A2780 cells.

Information Gradient among Nucleotide Sequences of Essential RNAs from an Evolutionary Perspective.

We hypothesize that the first ancestral "protocell" molecular structures, i.e., the first RNAs and peptides that gradually transformed into real cells once the Earth had cooled sufficiently for organic molecules to appear, have left traces in the RNAs and the genes in present cells. We propose a circular RNA that could have been one of these ancestral structures whose vestigial pentameric subsequences would mark the evolution from this key moment when the protocells began to join with living organisms. In particular, we propose that, in present RNAs (ribosomal or messenger), which play an important role in the metabolism of current cells, we look for traces of the proposed primitive structure in the form of pentamers (or longer fragments) that belong to their nucleotide sequence. The result obtained can be summarized in the existence of a gradient of occurrence of such pentamers, with a high frequency for the most vital functions (protein synthesis, nucleic synthesis, cell respiration, etc.). This gradient is also visible between organisms, from the oldest (Archaea) to the most recent (Eukaryotes) in the evolution of species.

Identification and Functional Analysis of circRNAs during Goat Follicular Development.

Litter size is a crucial quantitative trait in animals, closely linked to follicular development. Circular RNA (circRNA), a type of single-stranded closed-loop endogenous RNA with stable expression, plays pivotal roles in various biological processes, yet its function in goat follicular development remains unclear. In this study, we collected large (follicle diameter > 3 mm) and small (1 mm < follicle diameter < 3 mm) follicles from black goats in the Chuanzhong region for circRNA sequencing, with the aim of elucidating the functional circRNAs that influence follicle development in goats. Differential analysis revealed that 17 circRNAs were upregulated in large follicles, and 28 circRNAs were upregulated in small follicles. Functional enrichment analysis revealed significant enrichment of pathways related to reproduction, including cellular response to follicle-stimulating hormone stimulus, the PI3K-Akt signaling pathway, the MAPK signaling pathway, and the Notch signaling pathway. Based on the ceRNA mechanism, 45 differentially expressed circRNAs were found to target and bind a total of 418 miRNAs, and an intercalation network including miR-324-3p (circRNA2497, circRNA5650), miR-202-5p (circRNA3333, circRNA5501), and miR-493-3p (circRNA4995, circRNA5508) was constructed. In addition, conservation analysis revealed that 2,239 circRNAs were conserved between goats and humans. Prediction of translation potential revealed that 154 circRNAs may potentially utilize both N6-methyladenosine (m6A) and internal ribosome entry site (IRES) translation mechanisms. Furthermore, the differential expression and circularization cleavage sites of five circRNAs were validated through RT-qPCR and DNA sequencing. Our study constructed a circRNA map in goat follicle development, offering a theoretical foundation for enhancing goat reproductive performance.

Mechanistic and therapeutic perspectives of non-coding RNA-modulated apoptotic signaling in diabetic retinopathy.

Diabetic retinopathy (DR), a significant and vision-endangering complication associated with diabetes mellitus, constitutes a substantial portion of acquired instances of preventable blindness. The progression of DR appears to prominently feature the loss of retinal cells, encompassing neural retinal cells, pericytes, and endothelial cells. Therefore, mitigating the apoptosis of retinal cells in DR could potentially enhance the therapeutic approach for managing the condition by suppressing retinal vascular leakage. Recent advancements have highlighted the crucial regulatory roles played by non-coding RNAs (ncRNAs) in diverse biological processes. Recent advancements have highlighted that non-coding RNAs (ncRNAs), including microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs), act as central regulators in a wide array of biogenesis and biological functions, exerting control over gene expression associated with histogenesis and cellular differentiation within ocular tissues. Abnormal expression and activity of ncRNAs has been linked to the regulation of diverse cellular functions such as apoptosis, and proliferation. This implies a potential involvement of ncRNAs in the development of DR. Notably, ncRNAs and apoptosis exhibit reciprocal regulatory interactions, jointly influencing the destiny of retinal cells. Consequently, a thorough investigation into the complex relationship between apoptosis and ncRNAs is crucial for developing effective therapeutic and preventative strategies for DR. This review provides a fundamental comprehension of the apoptotic signaling pathways associated with DR. It then delves into the mutual relationship between apoptosis and ncRNAs in the context of DR pathogenesis. This study advances our understanding of the pathophysiology of DR and paves the way for the development of novel therapeutic strategies.

Circ_0000069 promotes the development of hepatocellular carcinoma by regulating CCL25.

BACKGROUND: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths globally, influenced by aberrant circRNA expression. Investigating circRNA-miRNA-mRNA interactions can unveil underlying mechanisms of HCC and identify potential therapeutic targets. METHODS: In this study, we conducted differential analyses of mRNAs, miRNAs, and circRNAs, and established their relationships using various databases such as miRanda, miRDB, and miTarBase. Additionally, functional enrichment and immune infiltration analyses were performed to evaluate the roles of key genes. We also conducted qPCR assays and western blotting (WB) to examine the expression levels of circRNA, CCL25, and MAP2K1 in both HCC cells and clinical samples. Furthermore, we utilized overexpression and knockdown techniques for circ_0000069 and conducted wound healing, transwell invasion assays, and a tumorigenesis experiment to assess the migratory and invasive abilities of HCC cells. RESULTS: Our findings revealed significant differential expression of 612 upregulated genes and 1173 downregulated genes in HCC samples compared to normal liver tissue. Additionally, 429 upregulated circRNAs and 453 downregulated circRNAs were identified. Significantly, circ_0000069 exhibited upregulation in HCC tissues and cell lines. The overexpression of circ_0000069 notably increased the invasion and migration capacity of Huh7 cells, whereas the downregulation of circ_0000069 reduced this capability in HepG2 cells. Furthermore, this effect was counteracted by CCL25 silencing or overexpression, separately. Animal studies further confirmed that the overexpression of hsa_circ_0000069 facilitated tumor growth in xenografted nude mice, while the inhibition of CCL25 attenuated this effect. CONCLUSION: Circ_0000069 appears to promote HCC progression by regulating CCL25, suggesting that both circ_0000069 and CCL25 can serve as potential therapeutic targets.

ESRP1-mediated biogenesis of circPTPN12 inhibits hepatocellular carcinoma progression by PDLIM2/ NF-κB pathway.

BACKGROUND: Emerging evidence indicates the pivotal involvement of circular RNAs (circRNAs) in cancer initiation and progression. Understanding the functions and underlying mechanisms of circRNAs in tumor development holds promise for uncovering novel diagnostic indicators and therapeutic targets. In this study, our focus was to elucidate the function and regulatory mechanism of hsa-circ-0003764 in hepatocellular carcinoma (HCC). METHODS: A newly discovered hsa-circ-0003764 (circPTPN12) was identified from the circbase database. QRT-PCR analysis was utilized to assess the expression levels of hsa-circ-0003764 in both HCC tissues and cells. We conducted in vitro and in vivo experiments to examine the impact of circPTPN12 on the proliferation and apoptosis of HCC cells. Additionally, RNA-sequencing, RNA immunoprecipitation, biotin-coupled probe pull-down assays, and FISH were employed to confirm and establish the relationship between hsa-circ-0003764, PDLIM2, OTUD6B, P65, and ESRP1. RESULTS: In HCC, the downregulation of circPTPN12 was associated with an unfavorable prognosis. CircPTPN12 exhibited suppressive effects on the proliferation of HCC cells both in vitro and in vivo. Mechanistically, RNA sequencing assays unveiled the NF-κB signaling pathway as a targeted pathway of circPTPN12. Functionally, circPTPN12 was found to interact with the PDZ domain of PDLIM2, facilitating the ubiquitination of P65. Furthermore, circPTPN12 bolstered the assembly of the PDLIM2/OTUD6B complex by promoting the deubiquitination of PDLIM2. ESRP1 was identified to bind to pre-PTPN12, thereby fostering the generation of circPTPN12. CONCLUSIONS: Collectively, our findings indicate the involvement of circPTPN12 in modulating PDLIM2 function, influencing HCC progression. The identified ESRP1/circPTPN12/PDLIM2/NF-κB axis shows promise as a novel therapeutic target in the context of HCC.

PTBP1-mediated biogenesis of circATIC promotes progression and cisplatin resistance of bladder cancer.

Background: Cisplatin (DDP) based combination chemotherapy is a vital method for the treatment of bladder cancer (BLca). Chemoresistance easily occurs in the course of cisplatin chemotherapy, which is one of the important reasons for the unfavorable prognosis of BLca patients. Circular RNAs (circRNAs) are widely recognized for their role in the development and advancement of BLca. Nevertheless, the precise role of circRNAs in DDP resistance for BLca remains unclear. Methods: To study the properties of circATIC, sanger sequencing, agarose gel electrophoresis and treatment with RNase R/Actinomycin D were utilized. RT-qPCR assay was utilized to assess the expression levels of circRNA, miRNA and mRNA in BLca tissues and cells. Functional experiments were conducted to assess the function of circATIC in BLca progression and chemosensitivity in vitro. Various techniques such as FISH, Dual-luciferase reporter assay, TRAP, RNA digestion assay, RIP and ChIRP assay were used to investigate the relationships between PTBP1, circATIC, miR-1247-5p and RCC2. Orthotopic bladder cancer model, xenograft subcutaneous tumor model and xenograft lung metastasis tumor model were performed to indicate the function and mechanism of circATIC in BLca progression and chemosensitivity in vivo. Results: In our study, we observed that circATIC expression was significantly enhanced in BLca tissues and cells and DDP resistant cells. Patients with higher circATIC expression have larger tumor diameter, higher incidence of postoperative metastasis and lower overall survival rate. Further experiments showed that circATIC accelerated BLca cell growth and metastasis and induced DDP resistance. Mechanistically, alternative splicing enzyme PTBP1 mediated the synthesis of circATIC. circATIC could enhance RCC2 mRNA stability via sponging miR-1247-5p or constructing a circATIC/LIN28A/RCC2 RNA-protein ternary complex. Finally, circATIC promotes RCC2 expression to enhance Epithelial-Mesenchymal Transition (EMT) progression and activate JNK signal pathway, thus strengthening DDP resistance in BLca cells. Conclusion: Our study demonstrated that circATIC promoted BLca progression and DDP resistance, and could serve as a potential target for BLca treatment.

Microglial circ-UBE2K exacerbates depression by regulating parental gene UBE2K via targeting HNRNPU.

Background: Knowledge about the pathogenesis of depression and treatments for this disease are lacking. Epigenetics-related circRNAs are likely involved in the mechanism of depression and have great potential as treatment targets, but their mechanism of action is still unclear. Methods: Circular RNA UBE2K (circ-UBE2K) was screened from peripheral blood of patients with major depressive disorder (MDD) and brain of depression model mice through high-throughput sequencing. Microinjection of circ-UBE2K overexpression lentivirus and adeno-associated virus for interfering with microglial circ-UBE2K into the mouse hippocampus was used to observe the role of circ-UBE2K in MDD. Sucrose preference, forced swim, tail suspension and open filed tests were performed to evaluate the depressive-like behaviors of mice. Immunofluorescence and Western blotting analysis of the effects of circ-UBE2K on microglial activation and immune inflammation. Pull-down-mass spectrometry assay, RNA immunoprecipitation (RIP) test and fluorescence in situ hybridization (FISH) were used to identify downstream targets of circ-UBE2K/ HNRNPU (heterogeneous nuclear ribonucleoprotein U) axis. Results: In this study, through high-throughput sequencing and large-scale screening, we found that circ-UBE2K levels were significantly elevated both in the peripheral blood of patients with MDD and in the brains of depression model mice. Functionally, circ-UBE2K-overexpressing mice exhibited worsened depression-like symptoms, elevated brain inflammatory factor levels, and abnormal microglial activation. Knocking down circ-UBE2K mitigated these changes. Mechanistically, we found that circ-UBE2K binds to heterogeneous nuclear ribonucleoprotein U (HNRNPU) to form a complex that upregulates the expression of the parental gene ubiquitin conjugating enzyme E2 K (UBE2K), leading to abnormal microglial activation and neuroinflammation and promoting the occurrence and development of depression. Conclusions: The findings of the present study revealed that the expression of circUBE2K, which combines with HNRNPU to form the circUBE2K/HNRNPU complex, is increased in microglia after external stress, thus regulating the expression of the parental gene UBE2K and mediating the abnormal activation of microglia to induce neuroinflammation, promoting the development of MDD. These results indicate that circ-UBE2K plays a newly discovered role in the pathogenesis of depression.

Circ-IP6K2 suppresses tumor progression by modulating the miR-1292-5p/CAMK2N1 signal in clear cell renal cell carcinoma.

Renal cell carcinoma (RCC) is a malignant tumor originating from the epithelial cells of the renal tubules. The clear cell RCC subtype is closely linked to a poor prognosis due to its rapid progression. Circular RNA (circRNA) is a novel class of regulatory RNA molecules that play a role in the development of ccRCC, although their functions have not been fully elucidated. In this study, we identified a significant downregulation of circ-IP6K2 in ccRCC tissues based on data from the GSE100186 dataset. The decreased expression of circ-IP6K2 correlated with the progression of TNM stage and histological grade, and was also associated with decreased overall survival rates in ccRCC patients. Moreover, our findings revealed that circ-IP6K2 expression suppressed proliferation, migration, and invasion capabilities in vitro, and inhibited xenograft growth in vivo. Mechanistically, circ-IP6K2 acted as a sponge for miR-1292-5p in ccRCC cells, which in turn targeted the 3'UTR of CAMK2N1, leading to a decrease in its expression. CAMK2N1 was identified as a tumor suppressor that negatively regulated the ß-catenin/c-Myc oncogenic signaling pathway. Additionally, we confirmed a positive correlation between the expression of circ-IP6K2 and CAMK2N1 in ccRCC. Circ-IP6K2 functions to impede the progression of ccRCC by modulating the miR-1292-5p/CAMK2N1 axis. These findings shed new light on the molecular mechanisms driving ccRCC progression and suggest potential therapeutic targets for the treatment of ccRCC.

N6-methyladenosine modification of circMARK2 enhances cytoplasmic export and stabilizes LIN28B, contributing to the progression of Wilms tumor.

BACKGROUND: The potential involvement of circular RNAs (circRNAs) and N6-methyladenosine (m6A) modification in the progression of Wilms tumor (WT) has not been fully elucidated. This study investigates the regulatory mechanisms and clinical significance of m6A-modified circMARK2 and its role in WT progression. METHODS: We identified dysregulated circRNAs through deep sequencing and validated their expression by qRT-PCR in WT tissues. The biological functions of circMARK2 were assessed using clone formation, transwell migration, and orthotopic animal models. To dissect the underlying mechanisms, we employed RNA immunoprecipitation, RNA pull-down, dual-luciferase reporter assays, Western blotting, and immunofluorescence and immunohistochemical staining. RESULTS: CircMARK2, upregulated in WT tissues, was found to be m6A-modified and promoted cytoplasmic export. It facilitated WT progression by stabilizing LIN28B mRNA through the circMARK2/IGF2BP2 interaction. In vitro and in vivo studies demonstrated that circMARK2 enhances the malignant behavior of WT cells. Clinically, higher circMARK2 levels in tumor tissues of WT patients were linked to increased tumor aggressiveness and reduced survival rates. CONCLUSIONS: Our study provides the first comprehensive evidence that m6A-modified circMARK2 contributes to WT progression by enhancing LIN28B mRNA stability, promoting cellular aggressiveness. CircMARK2 emerges as a potential biomarker for prognosis and a promising target for therapeutic intervention in WT, underscoring the clinical relevance of m6A modification in pediatric renal cancer.