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.

CircRNAs: Pivotal modulators of TGF-β signalling in cancer pathogenesis

The intricate molecular landscape of cancer pathogenesis continues to captivate researchers worldwide, with Circular RNAs (circRNAs) emerging as pivotal players in the dynamic regulation of biological functions. The study investigates the elusive link between circRNAs and the Transforming Growth Factor-β (TGF-β) signalling pathway, exploring their collective influence on cancer progression and metastasis. Our comprehensive investigation begins by profiling circRNA expression patterns in diverse cancer types, revealing a repertoire of circRNAs intricately linked to the TGF-β pathway. Through integrated bioinformatics analyses and functional experiments, we elucidate the specific circRNA-mRNA interactions that modulate TGF-β signalling, unveiling the regulatory controls governing this crucial pathway. Furthermore, we provide compelling evidence of the impact of circRNA-mediated TGF-β modulation on key cellular processes, including epithelial-mesenchymal transition (EMT), migration, and cell proliferation. In addition to their mechanistic roles, circRNAs have shown promise as diagnostic and prognostic biomarkers, as well as potential molecular targets for cancer therapy. Their ability to modulate critical pathways, such as the TGF-β signalling axis, underscores their significance in cancer biology and clinical applications. The intricate interplay between circRNAs and TGF-β is dissected, uncovering novel regulatory circuits that contribute to the complexity of cancer biology. This review unravels a previously unexplored dimension of carcinogenesis, emphasizing the crucial role of circRNAs in shaping the TGF-β signalling landscape.

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.

Intracellular Staphylococcus aureus infection in human osteoblasts: circRNA expression analysis

Staphylococcus aureus (S. aureus) has the ability to invade human cortical bones and cause intracellular infections in osteoblasts, which may lead to a long-term infection that is difficult to eliminate. It is critical to identify the underlying mechanisms of the osteoblast response to the intracellular S. aureus. More recently, multiple circular RNA (circRNA) functions have been identified, including serving as protein scaffolds or miRNA sponges and being translated into polypeptides. The role that circRNAs play in intracellular S. aureus infection of osteoblasts has not, to our knowledge, been investigated. Here, we established an intracellular infection model of S. aureus in osteoblasts and compared the circRNA expression of osteoblasts between the infected and control groups using RNA sequencing technology, by which a significant difference was found. In total, 117 upregulated and 125 down-regulated differentially expressed circRNAs (DEcircRNAs) were identified, and reverse transcription-quantitative PCR was employed to validate the results of RNA sequencing. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses demonstrated that DEcircRNAs were enriched in processes associated with macromolecule modification, cellular component organization or biogenesis, and intracellular non-membrane-bound organelles. Finally, a potentially important network of circRNA-miRNA-mRNA based on the DEcircRNAs was constructed. Overall, this study revealed the circRNA expression profile of human osteoblasts infected by intracellular S. aureus for the first time, and identified the circRNAs that may contribute to the pathogenesis of infectious diseases caused by intracellular S. aureus infection in human osteoblasts.

Optical Nanobiosensor Based on Surface-Enhanced Raman Spectroscopy and Catalytic Hairpin Assembly for Early-Stage Lung Cancer Detection via Blood Circular RNA

Lung cancer has become the leading cause of cancer-related deaths globally. However, early detection of lung cancer remains challenging, resulting in poor outcomes for the patients. Herein, we developed an optical biosensor integrating surface-enhanced Raman spectroscopy (SERS) with a catalyzed hairpin assembly (CHA) to detect circular RNA (circRNA) associated with tumor formation and progression (circSATB2). The signals of the Raman reporter were considerably enhanced by generating abundant SERS "hot spots" with a core-shell nanoprobe and 2D SERS substrate with calibration capabilities. This approach enabled the sensitive (limit of detection: 0.766 fM) and reliable quantitative detection of the target circRNA. Further, we used the developed biosensor to detect the circRNA in human serum samples, revealing that patients with lung cancer had higher circRNA concentrations than healthy subjects. Moreover, we characterized the unique circRNA concentration profiles of the early stages (IA and IB) and subtypes (IA1, IA2, and IA3) of lung cancer. These results demonstrate the potential of the proposed optical sensing nanoplatform as a liquid biopsy and prognostic tool for the early screening of lung cancer.

Circular RNAs Mediate the Effects of Dietary Tryptophan on the Transformation of Muscle Fiber Types in Weaned Piglets

The nutritional composition of the diet significantly impacts the overall growth and development of weaned piglets. The current study aimed to explore the effects and underlying mechanisms of dietary tryptophan consumption on muscle fiber type transformation during the weaning period. Thirty weaned piglets with an average body weight of 6.12 ± 0.16 kg were randomly divided into control (CON, 0.14% Trp diet) and high Trp (HT, 0.35% Trp) groups and maintained on the respective diet for 28 days. The HT group of weaned piglets exhibited highly significant improvements in growth performance and an increased proportion of fast muscle fibers. Transcriptome sequencing revealed the potential contribution of differentially expressed circular RNAs toward the transformation of myofiber types in piglets and toward the regulation of expression of related genes by targeting the microRNAs, miR-34c and miR-182, to further regulate myofiber transformation. In addition, 145 DE circRNAs were identified as potentially protein-encoding, with the encoded proteins associated with a myofiber type transformation. In conclusion, the current study greatly advances and refines our current understanding of the regulatory networks associated with piglet muscle development and myofiber type transformation and also contributes to the optimization of piglet diet formulation.

Noncoding RNA Contribution to Aging and Lifespan

Aging is a multifactorial process characterized by an age-related decline in organismal fitness. This deterioration is the major risk factor for chronic diseases such as cardiovascular pathologies, neurodegeneration, or cancer, and it represents one of the main challenges of modern society. Therefore, understanding why and how we age would be a fundamental pillar to design strategies to promote a healthy aging. In the last decades, the study of the molecular bases of disease has been revolutionized by the discovery of different types of noncoding RNAs (ncRNAs) with regulatory potential. In this work, we will review the implication of ncRNAs in aging, with the aim to provide a first approach to the different aging-associated ncRNAs, their mechanism of action, and their potential relevance as therapeutic targets and disease biomarkers.

Pulling the trigger: Noncoding RNAs in white adipose tissue browning

White adipose tissue (WAT) serves as the primary site for energy storage and endocrine regulation in mammals, while brown adipose tissue (BAT) is specialized for thermogenesis and energy expenditure. The conversion of white adipocytes to brown-like fat cells, known as browning, has emerged as a promising therapeutic strategy for reversing obesity and its associated co-morbidities. Noncoding RNAs (ncRNAs) are a class of transcripts that do not encode proteins but exert regulatory functions on gene expression at various levels. Recent studies have shed light on the involvement of ncRNAs in adipose tissue development, differentiation, and function. In this review, we aim to summarize the current understanding of ncRNAs in adipose biology, with a focus on their role and intricate mechanisms in WAT browning. Also, we discuss the potential applications and challenges of ncRNA-based therapies for overweight and its metabolic disorders, so as to combat the obesity epidemic in the future.

Mining key circRNA-associated-ceRNA networks for milk fat metabolism in cows with varying milk fat percentages

BACKGROUND

Cow milk fat is an essential indicator for evaluating and measuring milk quality and cow performance. Growing research has identified the molecular functions of circular RNAs (circRNAs) necessary for mammary gland development and lactation in mammals.

METHOD

The present study analyzed circRNA expression profiling data in mammary epithelial cells (MECs) from cows with highly variable milk fat percentage (MFP) using differential expression analysis and weighted gene co-expression network analysis (WGCNA).

RESULTS

A total of 309 differentially expressed circRNAs (DE-circRNAs) were identified in the high and low MFP groups. WGCNA analysis revealed that the pink module was significantly associated with MFP (r = - 0.85, P = 0.007). Parental genes of circRNAs in this module were enriched mainly in lipid metabolism-related signaling pathways, such as focal adhesion, ECM-receptor interaction, adherens junction and AMPK. Finally, six DE-circRNAs were screened from the pink module: circ_0010571, circ_0007797, circ_0002746, circ_0003052, circ_0004319, and circ_0012840. Among them, circ_0002746, circ_0003052, circ_0004319, and circ_0012840 had circular structures and were highly expressed in mammary tissues. Subcellular localization revealed that these four DE-circRNAs may play a regulatory role in the mammary glands of dairy cows, mainly as competitive endogenous RNAs (ceRNAs). Seven hub target genes (GNB1, GNG2, PLCB1, PLCG1, ATP6V0C, NDUFS4, and PIGH) were obtained by constructing the regulatory network of their ceRNAs and then analyzed by CytoHubba and MCODE plugins in Cytoscape. Functional enrichment analysis revealed that these genes are crucial and most probable ceRNA regulators in milk fat metabolism.

CONCLUSIONS

Our study identified several vital circRNAs and ceRNAs affecting milk fat synthesis, providing new research ideas and a theoretical basis for cow lactation, milk quality, and breed improvement.

Circular RNAs: characteristics, functions, mechanisms, and potential applications in thyroid cancer

Thyroid cancer (TC) is one of the most common endocrine malignancies, and its incidence has increased globally. Despite extensive research, the underlying molecular mechanisms of TC remain partially understood, warranting continued exploration of molecular markers for diagnostic and prognostic applications. Circular RNAs (circRNAs) have recently garnered significant attention owing to their distinct roles in cancers. This review article introduced the classification and biological functions of circRNAs and summarized their potential as diagnostic and prognostic markers in TC. Further, the interplay of circRNAs with PI3K/Akt/mTOR, Wnt/β-catenin, MAPK/ERK, Notch, JAK/STAT, and AMPK pathways is elaborated upon. The article culminates with an examination of circRNA's role in drug resistance of TC and highlights the challenges in circRNA research in TC.

Construction of a novel mRNA-miRNA-lncRNA/circRNA triple subnetwork associated with immunity and aging in intervertebral disc degeneration

OBJECTIVE

Intervertebral disk degeneration (IVDD) is one of the most common causes of low back pain. However, in the etiology of IVDD, the specific method by which nucleus pulposus (NP) cell senescence and the immune response induce disease is uncertain.

METHODS

Gene Expression Omnibus database was used to find differentially expressed genes (DEGs), differentially expressed miRNAs (DE miRNAs), differentially expressed lncRNAs (DE lncRNAs), and differentially expressed circRNAs (DE circRNAs). Functional enrichment analysis was performed through Enrichr database. Potential regulatory miRNAs, lncRNAs and circRNAs of mRNAs were predicted by ENCORI and circBank, respectively.

RESULTS

We identified 198 upregulated and 131 downregulated genes, 39 upregulated and 22 downregulated miRNAs, 2152 upregulated and 564 downregulated lncRNAs, and 352 upregulated and 279 downregulated circRNAs as DEGs, DE miRNAs, DE lncRNAs, DE circRNAs, respectively. Functional enrichment analysis revealed that they were significantly enriched in Toll-like receptor signaling route and the NF-kappa B signaling pathway. An mRNA-miRNA-lncRNA/circRNA network linked to the pathogenesis of NP cells in IVDD was constructed based on node degree and differential expression level. Eight immune-related DEGs (6 upregulated and 2 downregulated genes) and five aging-related DEGs (3 upregulated and 2 downregulated genes) were identified in the critical network.

CONCLUSION

We established a novel immune-related and aging-related triple regulatory network of mRNA-miRNA-lncRNA/circRNA ceRNA, among which all RNAs may be utilized as the pathogenesis biomarker of NP cells in IVDD.

Noncoding RNA Lipotherapeutics: A Promising Breakthrough in Pulmonary Hypertension Treatment

Pulmonary Hypertension (PH) is a complex cardiovascular disorder characterized by elevated blood pressure in the pulmonary arteries. Current therapeutic approaches for PH have limitations in addressing the underlying molecular mechanisms. This article explores the potential of noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), delivered through Lipid-Based Nanoparticles (LNPs) as a novel treatment strategy. These ncRNAs play critical roles in regulating vascular function and are implicated in PH pathogenesis. LNPs provide a promising method for the efficient and targeted delivery of ncRNAs. Advances in LNP technology, including the incorporation of R8 peptide modification, have shown promise in enhancing the delivery and efficacy of ncRNAs in PH models. Challenges such as biocompatibility, toxicity, and precise targeting must be addressed as these therapies move toward clinical application. The potential of personalized medicine and the integration of artificial intelligence in LNP design are discussed as prospects. In conclusion, ncRNA lipotherapeutics delivered via LNPs offer a transformative approach to treating PH, potentially leading to more effective management and improved patient outcomes in the future. However, continued research and clinical trials are necessary to fully realize their therapeutic potential in the field of PH treatment.

CircHAS2 activates CCNE2 to promote cell proliferation and sensitizes the response of colorectal cancer to anlotinib

BACKGROUND

Tyrosine kinase inhibitors (TKIs) are crucial in the targeted treatment of advanced colorectal cancer (CRC). Anlotinib, a multi-target TKI, has previously been demonstrated to offer therapeutic benefits in previous studies. Circular RNAs (circRNAs) have been implicated in CRC progression and their unique structural stability serves as promising biomarkers. The detailed molecular mechanisms and specific biomarkers related to circRNAs in the era of targeted therapies, however, remain obscure.

METHODS

The whole transcriptome RNA sequencing and function experiments were conducted to identify candidate anlotinib-regulated circRNAs, whose mechanism was confirmed by molecular biology experiments. CircHAS2 was profiled in a library of patient-derived CRC organoids (n = 22) and patient-derived CRC tumors in mice. Furthermore, a prospective phase II clinical study of 14 advanced CRC patients with anlotinib-based therapy was commenced to verify drug sensitivity (ClinicalTrials.gov identifier: NCT05262335).

RESULTS

Anlotinib inhibits tumor growth in vitro and in vivo by downregulating circHAS2. CircHAS2 modulates CCNE2 activation by acting as a sponge for miR-1244, and binding to USP10 to facilitate p53 nuclear export as well as degradation. In parallel, circHAS2 serves as a potent biomarker predictive of anlotinib sensitivity, both in patient-derived organoids and xenograft models. Moreover, the efficacy of anlotinib inclusion into the treatment regimen yields meaningful clinical responses in patients with high levels of circHAS2. Our findings offer a promising targeted strategy for approximately 52.9% of advanced CRC patients who have high circHAS2 levels.

CONCLUSIONS

CircHAS2 promotes cell proliferation via the miR-1244/CCNE2 and USP10/p53/CCNE2 bidirectional axes. Patient-derived organoids and xenograft models are employed to validate the sensitivity to anlotinib. Furthermore, our preliminary Phase II clinical study, involving advanced CRC patients treated with anlotinib, confirmed circHAS2 as a potential sensitivity marker.

Epigenetic regulation of hepatocellular carcinoma progression: microRNAs as therapeutic, diagnostic and prognostic factors

Hepatocellular carcinoma (HCC), a significant challenge for public healthcare systems in developed Western countries including the USA, Canada, and the UK, is influenced by different risk factors including hepatitis virus infections, alcoholism, and smoking. The disruption in the balance of microRNAs (miRNAs) plays a vital function in tumorigenesis, given their function as regulators in numerous signaling networks. These miRNAs, which are mature and active in the cytoplasm, work by reducing the expression of target genes through their impact on mRNAs. MiRNAs are particularly significant in HCC as they regulate key aspects of the tumor, like proliferation and invasion. Additionally, during treatment phases such as chemotherapy and radiotherapy, the levels of miRNAs are key determinants. Pre-clinical experiments have demonstrated that altered miRNA expression contributes to HCC development, metastasis, drug resistance, and radio-resistance, highlighting related molecular pathways and processes like MMPs, EMT, apoptosis, and autophagy. Furthermore, the regulatory role of miRNAs in HCC extends beyond their immediate function, as they are also influenced by other epigenetic factors like lncRNAs and circular RNAs (circRNAs), as discussed in recent reviews. Applying these discoveries in predicting the prognosis of HCC could mark a significant advancement in the therapy of this disease.

Hypoxia-induced circRNAs encoded by PPARA are highly expressed in human cardiomyocytes and are potential clinical biomarkers of acute myocardial infarction

BACKGROUND

Acute myocardial infarction (AMI) is a serious cardiovascular disease that adversely affects human health. Circular RNAs (circRNAs) are involved in the pathological and physiological processes of AMI, but the biological mechanism of their involvement and their clinical significance remain unknown. We aimed to identify circRNAs that are significantly associated with morbidity in the peripheral blood of patients with AMI and evaluate their diagnostic utility.

METHODS

High-throughput sequencing was used to screen for differentially expressed circRNAs in peripheral blood samples obtained from five patients with AMI and five sex- and age-matched healthy controls. A series of bioinformatics tools and databases were used to determine the biological functional classification and pathway enrichment of the circRNAs based on data obtained from sequencing. A hypoxia model was established and used to evaluate the effect of hypoxia on circRNA expression in human cardiomyocytes. A cytoplasmic separation assay and enzyme resistance assay were employed to identify the biological characteristics of circRNA. Polymerase chain reaction validity testing and receiver operating characteristic (ROC) curve analysis were used to evaluate the utility of circRNA assessments in the diagnosis of AMI.

RESULTS

A large number of circRNAs were found to be differentially expressed in the peripheral blood of patients with AMI, and significantly more of these circRNAs were highly expressed than lowly expressed. The genes encoding these circRNAs have a wide range of effects on various functions in the body. A hypoxic environment promoted the upregulation of circRNA expression in human cardiomyocytes, and hsa_circ_0116795 encoded by PPARA was highly expressed in the peripheral blood of the patients with AMI. In terms of biological characteristics, under physiological conditions, hsa_circ_0116795 (circ_PPARA) was mainly located in the cytoplasm of cardiomyocytes and found to be resistant to exonuclease. The ROC curve analysis showed that the expression levels of circ_PPARA in the peripheral blood of patients with AMI were significantly different from those in the peripheral blood of healthy controls.

CONCLUSION

A large number of abnormally expressed circRNAs are detectable in the peripheral blood of patients with AMI. In particular, circ_PPARA is highly expressed in human myocardial cells under hypoxic conditions, and its biological characteristics indicate that it could be employed as a biomarker for the early diagnosis of AMI.

Long noncoding RNAs and circular RNAs as potential diagnostic biomarkers of inflammatory bowel diseases: a systematic review and meta-analysis

Introduction

Inflammatory bowel disease (IBD) poses a growing global burden, necessitating the discovery of reliable biomarkers for early diagnosis. The clinical significance of dysregulated expression of long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) in diagnosing IBD has not been well established. Thus, our study aimed to investigate the diagnostic value of lncRNAs and circRNAs for IBD based on currently available studies.

Methods

A comprehensive search was carried out in diverse electronic databases, such as PubMed, Embase, Scopus, Science Direct and Wiley Online Library to retrieve articles published until October 30, 2023. Stata 17.0 software was employed to determine pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic ratio (DOR), and area under the curve (AUC). Heterogeneity, subgroup analysis, and meta-regression were explored, and publication bias was assessed using Deeks' funnel plot. Fagan's nomogram and likelihood ratio scattergram were employed to evaluate the clinical validity.

Result

A total of 11 articles encompassing 21 studies which involved 1239 IBD patients and 985 healthy controls were investigated. The findings revealed lncRNAs exhibit high level of pooled sensitivity 0.94 (95% CI: 0.87-0.97) and specificity 0.99 (95% CI: 0.89-1.00), along with PLR, NLR, DOR, and AUC values of 64.25 (95% CI: 7.39-558.66), 0.06 (95% CI: 0.03-0.13), 1055.25 (95% CI: 70.61-15770.77), and 0.99 (95% CI: 0.97-0.99), respectively. Conversely, CircRNAs showed moderate accuracy in IBD diagnosis, with sensitivity of 0.68 (95% CI: 0.61-0.73), specificity of 0.73 (95% CI: 0.65-0.79), PLR of 2.47 (95% CI: 1.94-3.16), NLR of 0.45 (95% CI: 0.38-0.53), DOR of 5.54 (95% CI: 3.88-7.93), and AUC value of 0.75 (95% CI: 0.71-0.79). Moreover, findings from subgroup analysis depicted heightened diagnostic efficacy when employing lncRNA H19 and a large sample size (≥100), with notable efficacy in diagnosing both ulcerative colitis (UC) and Crohn's disease (CD).

Conclusion

LncRNAs exhibit high diagnostic accuracy in distinguishing patients with IBD from healthy controls signifying their possible use as potential biomarkers, while circRNAs showed moderate diagnostic accuracy. Nevertheless, to validate our findings and confirm the clinical utility of lncRNAs and circRNAs in IBD diagnosis, a large pool of prospective and multi-center studies should be undertaken.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42023491840.

The Emerging Roles of Circpvt1 in Cancer Progression

CircRNA is stable due to its ring structure and is abundant in humans, which not only exists in various tissues and biofluids steadily but also plays a significant role in the physiology and pathology of human beings. CircPVT1, an endogenous circRNA, has recently been identified from the PVT1 gene located in the cancer risk region 8q24. CircPVT1 is reported to be highly expressed in many different tumors, where it affects tumor cell proliferation, apoptosis, invasion, and migration. We summarize the biosynthesis and biological functions of circPVT1 and analyze the relationship between circPVT1 and tumors as well as its significance to tumors. Further, it's noteworthy for the diagnosis, treatment, and prognosis of cancer patients. Therefore, circPVT1 is likely to become an innovative tumor marker.

Circular RNA in cervical cancer: Fundamental mechanism and clinical potential

CC (CC) remains a significant global health concern, imposing a substantial health burden on women worldwide due to its high incidence and mortality rates. To address this issue, there is a need for ongoing research to uncover the underlying molecular mechanisms of CC and to discover novel diagnostic and therapeutic strategies. Recent progress in non-coding RNAs (ncRNAs) has opened new avenues for investigation, and circular RNAs (circRNAs) have emerged as molecules with diverse roles in various cellular processes. These circRNAs are distinct in structure, forming a closed loop, setting them apart from their linear counterparts. They are intricately involved in regulating different aspects of cellular functions, particularly in cell growth and development. Remarkably, circRNAs can have varying functions, either promoting or inhibiting oncogenic processes, depending on the specific cellular context. Recent studies have identified abnormal circRNAs expression patterns associated with CC, indicating their significant involvement in disease development. The differing circRNAs profiles linked to CC present promising opportunities for early detection, precise prognosis evaluation, and personalized treatment strategies. In this comprehensive review, we embark on a detailed exploration of CC-related circRNAs, elucidating their distinct roles and providing insights into the intricate molecular mechanisms governing CC's onset and progression. A growing body of evidence strongly suggests that circRNAs can serve as valuable biomarkers for early CC detection and hold potential as therapeutic targets for intervention. By delving into the complex interplay between circRNAs and CC, we are paving the way for innovative, individualized approaches to combat this serious disease, with the goal of reducing its impact on women's health globally and improving patient outcomes. As our understanding of circRNAs in the context of CC continues to deepen, the outlook for breakthroughs in diagnosis and treatment becomes increasingly promising.

The potential role and mechanism of circRNAs in Ferroptosis: A comprehensive review

Cell death encompasses various mechanisms, including necrosis and apoptosis. Ferroptosis, a unique form of regulated cell death, emerged as a non-apoptotic process reliant on iron and reactive oxygen species (ROS). Distinguishing itself from other forms of cell death, ferroptosis exhibits distinct morphological, biochemical, and genetic features. Circular RNAs (circRNAs), a novel class of RNA molecules, play crucial regulatory roles in ferroptosis-mediated pathways and cellular processes. With their circular structure and stability, circRNAs function as microRNA sponges and participate in protein regulation, offering diverse mechanisms for cellular control. Accumulating evidence indicates that circRNAs are key players in diseases associated with ferroptosis, presenting opportunities for diagnostic and therapeutic applications. This study explores the regulatory roles of circRNAs in ferroptosis and their potential in diseases such as cancer, neurological disorders, and cardiovascular diseases. By investigating the relationship between circRNAs and ferroptosis, this research provides new insights into the diagnosis, treatment, and prognosis of ferroptosis-related diseases. Furthermore, the therapeutic implications of targeting circRNAs in cancer treatment and the modulation of ferroptosis pathways demonstrate the potential of circRNAs as diagnostic markers and therapeutic targets. Overall, understanding the involvement of circRNAs in regulating ferroptosis opens up new avenues for advancements in disease management.

Circular RNAs in intracranial aneurysms: Emerging roles in pathogenesis, diagnosis and therapeutic intervention

Intracranial aneurysms (IAs) present a substantial health threat, given the potential for catastrophic ruptures and subarachnoid hemorrhages (SAH). Swift and effective measures for diagnosis and treatment are paramount to enhance patient outcomes and alleviate the associated healthcare burden. In this context, circular RNAs (circRNAs) have emerged as an intriguing area of investigation, offering promise as both diagnostic biomarkers and therapeutic targets for IAs. CircRNAs have demonstrated their influence on critical molecular and cellular processes underpinning IAs pathogenesis, revealing their pivotal role in understanding this complex ailment. Beyond their diagnostic potential, circRNAs hold great potential as prognostic markers, providing crucial insights into IAs rupture risk. The unique circular structure and their regulatory functions make circRNAs an enticing avenue for innovative therapeutic approaches. The ongoing study of circRNAs in the context of IAs is an exciting and rapidly evolving field that has the potential to revolutionize approaches to diagnosis, treatment, and prevention of this life-threatening condition. As research continues to unravel the intricate roles of circRNAs, they are poised to become invaluable tools in clinical practice, enhancing patient care and ultimately reducing the impact of cerebral aneurysms on both individuals and healthcare systems. This comprehensive review delves deeply into the world of circRNAs in the realm of IAs, elucidating their multifaceted roles in the onset and progression of this condition. Moreover, this review ventures into the diagnosis and therapeutic potential of circRNAs, exploring their possible applications in gene therapy and as targets for novel treatment modalities.

Non-coding RNAs: targets for Chinese herbal medicine in treating myocardial fibrosis

Cardiovascular diseases have become the leading cause of death in urban and rural areas. Myocardial fibrosis is a common pathological manifestation at the adaptive and repair stage of cardiovascular diseases, easily predisposing to cardiac death. Non-coding RNAs (ncRNAs), RNA molecules with no coding potential, can regulate gene expression in the occurrence and development of myocardial fibrosis. Recent studies have suggested that Chinese herbal medicine can relieve myocardial fibrosis through targeting various ncRNAs, mainly including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Thus, ncRNAs are novel drug targets for Chinese herbal medicine. Herein, we summarized the current understanding of ncRNAs in the pathogenesis of myocardial fibrosis, and highlighted the contribution of ncRNAs to the therapeutic effect of Chinese herbal medicine on myocardial fibrosis. Further, we discussed the future directions regarding the potential applications of ncRNA-based drug screening platform to screen drugs for myocardial fibrosis.

Helicobacter pylori upregulates circPGD and promotes development of gastric cancer

PURPOSE

Helicobacter pylori (H. pylori) has unique biochemical traits and pathogenic mechanisms, which make it a substantial cause of gastrointestinal cancers. Circular RNAs (circRNAs) have concurrently been identified as an important participating factor in the pathophysiology of several different cancers. However, the underlying processes and putative interactions between H. pylori and circRNAs have received very little attention. To address this issue, we explored the interaction between H. pylori and circRNAs to investigate how they might jointly contribute to the occurrence and development of gastric cancer.

METHODS

Changes in circPGD expression in H. pylori were detected using qRT-PCR. Cell proliferation and migration changes were assayed by colony formation, the CCK-8 assay and the transwell assay. Apoptosis was measured by flow cytometry. Western blot was conducted to detect changes in cell migration, apoptosis, proliferation and inflammation-associated proteins. QRT-PCR was used to measure changes in circPGD and inflammation-associated factors.

RESULTS

We found that H. pylori induced increased circPGD expression in infected human cells and facilitated gastric cancer progression in three ways by promoting cell proliferation and migration, enhancing the inflammatory response, and inhibiting apoptosis.

CONCLUSIONS

CircPGD appears to play a role in H. pylori-related gastric cancer and may thus be a viable, novel target for therapeutic intervention.

Identification of circRNA-associated ceRNA networks in the longissimus dorsi of yak under different feeding systems

BACKGROUND

Yaks (Bos grunniens), prized for their ability to thrive in high-altitude environments, are indispensable livestock in the plateau region. Modifying their feeding systems holds significant promise for improving their growth and meat quality. Tenderness, a key determinant of yak meat quality and consumer appeal, is demonstrably influenced by dietary regimen. Indoor feeding regimes have been shown to enhance tenderness by lowering shear stress and optimizing pH values. CircRNAs, well-known modulators of circulatory function, also play a crucial role in skeletal muscle development across various animal species. However, their functional significance in yak skeletal muscle remains largely unexplored.

RESULTS

In this study, we identified a total of 5,534 circRNAs within the longissimus dorsi muscle, and we found 51 differentially expressed circRNAs (20 up-regulated and 31 down-regulated) between the two feeding groups. Constructing a comprehensive ceRNA network illuminated intricate regulatory mechanisms, with PGP and circRNA_0617 converging on bta-miR-2285q, mirrored by KLF15/circRNA_0345/bta-miR-20b and CTSF/circRNA_0348/bta-miR-146a. These findings shed light on the potential of circRNAs to influence yak muscle development and meat quality, offering valuable insights for future research.

CONCLUSIONS

This investigation unraveled a complex interaction network between circRNAs、mRNAs and miRNAs in yak skeletal muscle. We further elucidated the target genes regulated by these target genes within the network, offering valuable insights into the potential regulatory mechanisms governing muscle development and meat quality-related traits in yaks.

Genomic Alterations Affecting Competitive Endogenous RNAs (ceRNAs) and Regulatory Networks (ceRNETs) with Clinical Implications in Triple-Negative Breast Cancer (TNBC)

The concept of competitive endogenous RNA regulation has brought on a change in the way we think about transcriptional regulation by miRNA-mRNA interactions. Rather than the relatively simple idea of miRNAs negatively regulating mRNA transcripts, mRNAs and other non-coding RNAs can regulate miRNAs and, therefore, broad networks of gene products through competitive interactions. While this concept is not new, its significant roles in and implications on cancer have just recently come to light. The field is now ripe for the extrapolation of technologies with a substantial clinical impact on cancer. With the majority of the genome consisting of non-coding regions encoding regulatory RNAs, genomic alterations in cancer have considerable effects on these networks that have been previously unappreciated. Triple-negative breast cancer (TNBC) is characterized by high mutational burden, genomic instability and heterogeneity, making this aggressive breast cancer subtype particularly relevant to these changes. In the past few years, much has been learned about the roles of competitive endogenous RNA network regulation in tumorigenesis, disease progression and drug response in triple-negative breast cancer. In this review, we present a comprehensive view of the new knowledge and future perspectives on competitive endogenous RNA networks affected by genomic alterations in triple-negative breast cancer. An overview of the competitive endogenous RNA (ceRNA) hypothesis and its bearing on cellular function and disease is provided, followed by a thorough review of the literature surrounding key competitive endogenous RNAs in triple-negative breast cancer, the genomic alterations affecting them, key disease-relevant molecular and functional pathways regulated by them and the clinical implications and significance of their dysregulation. New knowledge of the roles of these regulatory mechanisms and the current acceleration of research in the field promises to generate insights into the diagnosis, classification and treatment of triple-negative breast cancer through the elucidation of new molecular mechanisms, therapeutic targets and biomarkers.

Predicting circRNA-RBP Binding Sites Using a Hybrid Deep Neural Network

Circular RNAs (circRNAs) are non-coding RNAs generated by reverse splicing. They are involved in biological process and human diseases by interacting with specific RNA-binding proteins (RBPs). Due to traditional biological experiments being costly, computational methods have been proposed to predict the circRNA-RBP interaction. However, these methods have problems of single feature extraction. Therefore, we propose a novel model called circ-FHN, which utilizes only circRNA sequences to predict circRNA-RBP interactions. The circ-FHN approach involves feature coding and a hybrid deep learning model. Feature coding takes into account the physicochemical properties of circRNA sequences and employs four coding methods to extract sequence features. The hybrid deep structure comprises a convolutional neural network (CNN) and a bidirectional gated recurrent unit (BiGRU). The CNN learns high-level abstract features, while the BiGRU captures long-term dependencies in the sequence. To assess the effectiveness of circ-FHN, we compared it to other computational methods on 16 datasets and conducted ablation experiments. Additionally, we conducted motif analysis. The results demonstrate that circ-FHN exhibits exceptional performance and surpasses other methods. circ-FHN is freely available at https://github.com/zhaoqi106/circ-FHN .

Functional Relevance of Extracellular Vesicle-Derived Long Non-Coding and Circular RNAs in Cancer Angiogenesis

Extracellular vesicles (EVs) are defined as subcellular structures limited by a bilayer lipid membrane that function as important intercellular communication by transporting active biomolecules, such as proteins, amino acids, metabolites, and nucleic acids, including long non-coding RNAs (lncRNAs). These cargos can effectively be delivered to target cells and induce a highly variable response. LncRNAs are functional RNAs composed of at least 200 nucleotides that do not code for proteins. Nowadays, lncRNAs and circRNAs are known to play crucial roles in many biological processes, including a plethora of diseases including cancer. Growing evidence shows an active presence of lnc- and circRNAs in EVs, generating downstream responses that ultimately affect cancer progression by many mechanisms, including angiogenesis. Moreover, many studies have revealed that some tumor cells promote angiogenesis by secreting EVs, which endothelial cells can take up to induce new vessel formation. In this review, we aim to summarize the bioactive roles of EVs with lnc- and circRNAs as cargo and their effect on cancer angiogenesis. Also, we discuss future clinical strategies for cancer treatment based on current knowledge of circ- and lncRNA-EVs.

circ_0039787 promotes cervical cancer cell tumorigenesis by regulation of the miR-877-5p-KRAS axis

Circular RNA (circRNA) is a novel type of RNA that plays an important role in the occurrence and development of many malignant tumors. However, the potential regulatory role and molecular mechanisms of circRNAs in cervical cancer (CC) are still not clear. Here, we explored circRNAs associated with CC from the Gene Expression Omnibus (GEO) datasets GSE113696 and GSE102686. We initially identified circ_0039787, which is derived from exons 2 to 3 of the C16orf70 gene. We observed that circ_0039787 is mainly located in the cytoplasm and is more stable than its linear counterpart, C16orf70. circ_0039787 is significantly upregulated in CC tissues and cells. In addition, functional gain and loss experiments demonstrated that circ_0039787 promotes the proliferation, migration, and invasion of CC cells in vitro and the growth of CC tumors in vivo. Mechanistically, circ_0039787 promotes CC tumor progression by competitively absorbing miR-877-5p to alleviate the inhibitory effect of miR-877-5p on Kirsten Rat Sarcoma viral oncogene homolog (KRAS) expression. Overall, our results suggest that circ_0039787 could serve as a promising diagnostic biomarker and potential therapeutic target for CC patients.

Physiological and pathological functions of circular RNAs in the nervous system

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

The important regulatory roles of circRNA‑encoded proteins or peptides in cancer pathogenesis (Review)

Circular RNAs (circRNAs) represent a class of RNA molecules characterized by their covalently closed structures. There are three types of circRNAs, namely exonic circRNAs, exon‑intron circRNAs and circular intronic RNAs. To date, four distinct mechanisms have been unveiled through which circRNAs exert their functional influence, including serving as microRNA (miRNA) sponges, interacting with RNA binding proteins (RBPs), modulating parental gene transcription and acting as templates for translation. Of note, among these mechanisms, the miRNA/RBP sponge function has been the most investigated one. Recent research has uncovered the presence of various proteins or peptides encoded by circRNA. CircRNAs are translated independent of the 5' cap and 3' polyA tail, which are typical elements for linear RNA translation. Some unique elements, such as internal ribosome entry sites and N‑methyladenosine modifications, facilitate the initiation of translation. These circRNA‑encoded proteins or peptides participate in diverse signalling pathways and act as important regulators in carcinogenesis by influencing cell proliferation, migration, apoptosis and other key processes. Consequently, circRNA‑encoded proteins or peptides have great potential as therapeutic targets for anticancer drugs. The present comprehensive review aimed to systematically summarize the current understanding of circRNA‑encoded proteins or peptides and to unveil their roles in carcinogenesis.

Circ0060467 sponges miR-6805 to promote hepatocellular carcinoma progression through regulating AIFM2 and GPX4 expression

BACKGROUND

Circular RNAs (circRNAs) represent a subset of non-coding RNAs implicated in the regulation of diverse biological processes, including tumorigenesis. However, the expression and functional implications of circ0060467 in hepatocellular carcinoma (HCC) remain elusive. In this study, we aimed to elucidate the role of circ0060467 in modulating the progression of HCC.

METHODS

Differentially expressed circRNAs in HCC tissues were identified through circRNA microarray assays. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays revealed the upregulation of circ0060467 in both HCC cell lines and tissues. Various assays were conducted to investigate the roles of circ0060467 in HCC progression. Additionally, RNA immunoprecipitation (RIP) assays and luciferase assays were carried out to assess the interactions between circ0060467, microRNA-6085 (miR-6085), apoptosis-inducing factor mitochondria-associated 2 (AIFM2), and glutathione peroxidase 4 (GPX4) in HCC.

RESULTS

Microarray and qRT-PCR analyses demonstrated a marked elevation of circ0060467 in HCC tissues and cell lines. Knockdown of circ0060467 suppressed HCC cell proliferation. Luciferase reporter and RIP assays confirmed the binding of circ0060467, AIFM2, and GPX4 to miR-6805. Subsequent experiments revealed that circ0060467 competes with AIFM2 and GPX4, thereby inhibiting cancer cell ferroptosis by binding to miR-6085 and promoting hepatocellular carcinoma progression.

CONCLUSIONS

Collectively, circ0060467 modulates the levels of AIFM2 and GPX4, crucial regulators of tumor cell ferroptosis, by acting as a sponge for miR-6085 in HCC. Thus, circ0060467 may represent a novel diagnostic marker and therapeutic target for HCC.

A Circular RNA Derived from the Pumilio 1 Gene Could Regulate PTEN in Human Cumulus Cells

CircRNAs are a class of non-coding RNAs able to regulate gene expression at multiple levels. Their involvement in physiological processes, as well as their altered regulation in different human diseases, both tumoral and non-tumoral, is well documented. However, little is known about their involvement in female reproduction. This study aims to identify circRNAs potentially involved in reproductive women's health. Candidate circRNAs expressed in ovary and sponging miRNAs, already known to be expressed in the ovary, were selected by a computational approach. Using real time PCR, we verified their expression and identified circPUM1 as the most interesting candidate circRNA for further analyses. We assessed the expression of circPUM1 and its linear counterpart in all the follicle compartments and, using a computational and experimental approach, identified circPUM1 direct and indirect targets, miRNAs and mRNAs, respectively, in cumulus cells. We found that both circPUM1 and its mRNA host gene are co-expressed in all the follicle compartments and proposed circPUM1 as a potential regulator of PTEN, finding a strong positive correlation between circPUM1 and PTEN mRNA. These results suggest a possible regulation of PTEN by circPUM1 in cumulus cells and point out the important role of circRNA inside the pathways related to follicle growth and oocyte maturation.

The Roles of Non-coding RNA Targeting Astrocytes in Cerebral Ischemia

Astrocytes are key targets for treating cerebral ischemia in the central nervous system. Non-coding RNAs (ncRNAs) participate in the pathological processes of astrocytes in cerebral ischemia. Recent reports suggest that ncRNAs ameliorate the outcome of cerebral ischemia by mediating astrocytes' inflammatory reaction, oxidative stress, excitotoxicity, autophagy, and apoptosis. Reconstructing cellular systems might offer a promising strategy for treating cerebral ischemia. This review briefly discusses the potential of ncRNAs as drug targets and explores the molecular regulatory mechanisms through which ncRNAs target astrocytes in cerebral ischemia. It provides an overview of the current research, discusses ncRNAs' implications as clinical markers for cerebral ischemia, and anticipates that ongoing research on ncRNAs may contribute to novel therapeutic approaches for treating this condition.

Non-coding RNAs in the pathophysiology of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is the largest unmet clinical need in cardiovascular medicine. Despite decades of research, the treatment option for HFpEF is still limited, indicating our ongoing incomplete understanding on the underlying molecular mechanisms. Non-coding RNAs, comprising of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), are non-protein coding RNA transcripts, which are implicated in various cardiovascular diseases. However, their role in the pathogenesis of HFpEF is unknown. Here, we discuss the role of miRNAs, lncRNAs and circRNAs that are involved in the pathophysiology of HFpEF, namely microvascular dysfunction, inflammation, diastolic dysfunction and cardiac fibrosis. We interrogated clinical evidence and dissected the molecular mechanisms of the ncRNAs by looking at the relevant in vivo and in vitro models that mimic the co-morbidities in patients with HFpEF. Finally, we discuss the potential of ncRNAs as biomarkers and potential novel therapeutic targets for future HFpEF treatment.

LncRNAs-circRNAs as Rising Epigenetic Binary Superstars in Regulating Lipid Metabolic Reprogramming of Cancers

As one of novel hallmarks of cancer, lipid metabolic reprogramming has recently been becoming fascinating and widely studied. Lipid metabolic reprogramming in cancer is shown to support carcinogenesis, progression, distal metastasis, and chemotherapy resistance by generating ATP, biosynthesizing macromolecules, and maintaining appropriate redox status. Notably, increasing evidence confirms that lipid metabolic reprogramming is under the control of dysregulated non-coding RNAs in cancer, especially lncRNAs and circRNAs. This review highlights the present research findings on the aberrantly expressed lncRNAs and circRNAs involved in the lipid metabolic reprogramming of cancer. Emphasis is placed on their regulatory targets in lipid metabolic reprogramming and associated mechanisms, including the clinical relevance in cancer through lipid metabolism modulation. Such insights will be pivotal in identifying new theranostic targets and treatment strategies for cancer patients afflicted with lipid metabolic reprogramming.

Roles of circular RNAs in osteogenic/osteoclastogenic differentiation

The process of bone remodeling occurs and is regulated through interactions between osteoclasts, which resorb bone, and osteoblasts, which generate bone tissue. When the homeostatic balance between these two cell types is dysregulated, this can contribute to abnormal bone remodeling resulting in a loss of bone mass as is observed in osteoporosis (OP) and other forms of degenerative bone metabolic diseases. At present, details of molecular mechanism underlying the development of bone metabolic diseases such as OP remain to be elucidated. Circular RNAs (circRNAs) are small non-coding RNA molecules with a closed-loop structure that can regulate the differentiation of osteoclasts and osteoblasts. The present review provides a systematic overview of recent literature on the processes through which circRNAs regulate the dynamic balance between osteoblasts and osteoclasts that ultimately preserve bone homeostasis. It will also give insight that can shape current understanding of the pathogenesis of OP and other bone metabolic diseases to better guide diagnostic and treatment strategies for affected patients.

Non-coding RNAs in hypertrophic scars and keloids: Current research and clinical relevance: A review

Hypertrophic scars (HS) and keloids (KD) are lesions that develop as a result of excessive fibroblast proliferation and collagen deposition in response to dermal injury, leading to dysregulation of the inflammatory, proliferative, and remodeling phases during wound healing. HS and KD affect up to 90 % of the population and are associated with lower quality of life, physical health, and mental status in patients. Efficient targeted treatment represents a significant challenge, primarily due to our limited understanding of their underlying pathogenesis. Non-coding RNAs (ncRNAs), which constitute a significant portion of the human transcriptome with minimal or no protein-coding capacity, have been implicated in various cellular physiologies and pathologies and may serve as diagnostic indicators or therapeutic targets. NcRNAs have been found to be aberrantly expressed and regulated in HS and KD. This review provides a summary of the expression profiles and molecular mechanisms of three common ncRNAs, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), in HS and KD. It also discusses their potential as biomarkers for the diagnosis and treatment of these diseases and provides novel insights into epigenetic-based diagnosis and treatment strategies for HS and KD.

Circular RNAs: Emerging Modulators in the Pathophysiology of Polycystic Ovary Syndrome and their Clinical Implications

Polycystic ovary syndrome (PCOS) is a prevalent endocrine/metabolic disorder in women of reproductive age. PCOS is characterized by hyperandrogenism, polycystic ovary morphology, and ovulatory dysfunction/anovulation. It involves multiple effects in patients, including granulosa/theca cell hyperplasia, menstrual disturbances, infertility, acne, obesity, insulin resistance, and cardiovascular disorders. Biochemical analyses and the results of RNA sequencing studies in recent years have shown a type of non-coding RNAs as a splicing product known as circular RNAs (circRNAs). Several biological functions have been identified in relation to circRNAs, including a role in miRNA sponge, protein sequestration, increased parental gene expression, and translation leading to polypeptides. These circular molecules are more plentiful and specialized than other types of RNAs. For this reason, they are referred to as potential biomarkers in different diseases. Evidence suggests that circRNAs may have regulatory potentials through different signaling pathways, such as the miRNA network. Probably most experts in the field of obstetricians are not aware of circRNAs as a useful biomarker. Therefore, this review focused on the researches that have been done on the involvement of circRNAs in PCOS and summarized recent supportive evidence, and evaluated the circRNA association and mechanisms involved in PCOS.

Evaluation of hsa_circ_0000018/let-7f-5p/ FAM96A axis in lung adenocarcinoma progression

BACKGROUND

Circular RNAs (circRNAs) are critical regulators of lung adenocarcinoma (LA) progression. Although a molecular marker targeting hsa_circ_0000018 has been developed and used for diagnosing colon cancer, the role of this circRNA in LA progression has not been explored till now.

OBJECTIVES

This study aimed to elucidate the role and regulatory mechanisms of hsa_circ_0000018 in LA progression.

METHODS

LA tissues and corresponding adjacent non-tumor tissues were collected from 36 patients to confirm the levels of circRNAs, microRNAs (miRNAs), and messenger RNAs (mRNAs) using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). We also cultured two LA cell lines (A549, PC-9), and the human normal lung epithelial cell line BEAS-2B. Cell function experiments were conducted to assess malignancy in LA cells, including proliferation, migration, and invasion, following forced hsa_circ_0000018 expression. The correlation between hsa_circ_0000018, let-7f-5p, and family with sequence similarity 96 member A (FAM96A) was confirmed by using starBase (miRNA-circRNA interaction database), luciferase assay, and western blotting.

RESULTS

Expression of hsa_circ_0000018 and FAM96A was reduced, whereas that of let-7f-5p was upregulated in LA. Cell function assays revealed that upregulation of hsa_circ_0000018 had a suppressive effect on the proliferation, migration, and invasion of LA cells. Additionally, hsa_circ_0000018 sponge binds let-7f-5p, resulting in upregulation of FAM96A expression.

CONCLUSION

Our data reveal hsa_circ_0000018 as a tumor suppressor in LA that targets the let-7f-5p/FAM96A axis. Our findings enrich the known regulatory network of circRNAs in LA.

Identification of Differential Circular RNA Expression Profiles and Functional Networks in Human Macrophages Induced by Virulent and Avirulent Mycobacterium tuberculosis Strains

Circular RNAs (circRNAs) are noncoding RNAs with diverse functions. However, most Mycobacterium tuberculosis (M.tb)-related circRNAs remain undiscovered. In this study, we infected THP-1 cells with virulent and avirulent M.tb strains and then sequenced the cellular circRNAs. Bioinformatic analysis predicted 58,009 circRNAs in all the cells. In total, 2035 differentially expressed circRNAs were identified between the M.tb-infected and uninfected THP-1 cells and 1258 circRNAs were identified in the virulent and avirulent M.tb strains. Further, the top 10 circRNAs were confirmed by Sanger sequencing, among which four circRNAs, namely circSOD2, circCHSY1, circTNFRSF21, and circDHTKD1, which were highly differentially expressed in infected cells compared with those in uninfected cells, were further confirmed by ring formation, specific primers, and RNase R digestion. Next, circRNA-miRNA-mRNA subnetworks were constructed, such as circDHTKD1/miR-660-3p/IL-12B axis. Some of the individual downstream genes, such as miR-660-3p and IL-12B, were previously reported to be associated with cellular defense against pathological processes induced by M.tb infection. Because macrophages are important immune cells and the major host cells of M.tb, these findings provide novel ideas for exploring the M.tb pathogenesis and host defense by focusing on the regulation of circRNAs during M.tb infection.

RNA landscapes of brain and brain-derived extracellular vesicles in simian immunodeficiency virus (SIV) infection and central nervous system pathology

INTRODUCTION

Brain tissue-derived extracellular vesicles (bdEVs) act locally in the central nervous system (CNS) and may indicate molecular mechanisms in HIV CNS pathology. Using brain homogenate (BH) and bdEVs from a simian immunodeficiency virus (SIV) model of HIV disease, we identified RNA networks in SIV infection and neuroinflammation.

METHODS

Postmortem occipital cortex samples were obtained from uninfected controls and SIV-infected subjects (acute and chronic phases with or without CNS pathology (SIV encephalitis). bdEVs were separated and characterized per international consensus guidelines. RNAs from bdEVs and BH were sequenced and qPCR-amplified to detect levels of small RNAs (sRNAs, including microRNAs (miRNAs)) and longer RNAs including messenger RNAs (mRNAs) and circular RNAs (circRNAs).

RESULTS

Dysregulated RNAs in BH and bdEVs were identified in acute and chronic infection with pathology groups, including mRNAs, miRNAs, and circRNAs. Most dysregulated mRNAs in bdEVs reflected dysregulation in source BH. These mRNAs are disproportionately involved in inflammation and immune responses. Based on target prediction, several circRNAs that were differentially abundant in source tissue might be responsible for specific differences in sRNA levels in bdEVs during SIV infection.

CONCLUSIONS

RNA profiling of bdEVs and source tissues reveals potential regulatory networks in SIV infection and SIV-related CNS pathology.

Antioxidants positively regulate obesity dependent circRNAs - sperm quality - functional axis

Obesity is a pathophysiological condition, dependent on body fat accumulation, that progressively induces systemic oxidative stress/inflammation leading to a set of associated clinical manifestations, including male infertility. CircRNAs, covalently closed RNA molecules, are key regulators of sperm quality. Recently, we have characterized a complete profile of high-fat diet (HFD) spermatic circRNA cargo, predicting paternal circRNA dependent networks (ceRNETs), potentially involved in sperm oxidative stress and motility anomalies. In the current work, using HFD C57BL6/J male mice, orally treated with a mix of bioactive molecules (vitamin C; vitamin B12; vitamin E; selenium-L-methionine; glutathione-GSH) for 4 weeks, a reversion of HFD phenotype was observed. In addition, the functional action of the proposed formulations on circRNA biogenesis was evaluated by assessing the endogenous spermatic FUS-dependent backsplicing machinery and related circRNA cargo. After that, spermatic viability and motility were also analyzed. Paternal ceRNETs, potentially involved in oxidative stress regulation and sperm motility defects, were identified and used to suggest that the beneficial action of the food supplements here conveniently formulated on sperm motility was likely due to the recovery of circRNA profile. Such a hypothesis was, then, verified by an in vitro assay.

Non-Coding RNAs and the Development of Chemoresistance to Docetaxel in Prostate Cancer: Regulatory Interactions and Approaches Based on Machine Learning Methods

Chemotherapy based on taxane-class drugs is the gold standard for treating advanced stages of various oncological diseases. However, despite the favorable response trends, most patients eventually develop resistance to this therapy. Drug resistance is the result of a combination of different events in the tumor cells under the influence of the drug, a comprehensive understanding of which has yet to be determined. In this review, we examine the role of the major classes of non-coding RNAs in the development of chemoresistance in the case of prostate cancer, one of the most common and socially significant types of cancer in men worldwide. We will focus on recent findings from experimental studies regarding the prognostic potential of the identified non-coding RNAs. Additionally, we will explore novel approaches based on machine learning to study these regulatory molecules, including their role in the development of drug resistance.

Long noncoding RNA/circular RNA regulates competitive endogenous RNA networks in rheumatoid arthritis: molecular mechanisms and traditional Chinese medicine therapeutic significances

Rheumatoid arthritis (RA) is a systemic and autoimmune disease that is mainly featured abnormal fibroblast-like synoviocyte (FLS) proliferation and inflammatory cell infiltration. Abnormal expression or function of long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) are closely related to human diseases, including RA. There has been increasing evidence showing that in the competitive endogenous RNA (ceRNA) networks, both lncRNA and circRNA are vital in the biological functions of cells. Nevertheless, the exact mechanism of ceRNA in RA remains to be investigated. Herein, we summarized the molecular potencies of lncRNA/circRNA-mediated ceRNA networks in RA, with emphasis on the phenotypic regulation of ceRNA in the progression of RA, including regulation of proliferation, invasion, inflammation and apoptosis, as well as the role of ceRNA in traditional Chinese medicine (TCM) in the treatment of RA. In addition, we also discussed the future direction and potential clinical value of ceRNA in the treatment of RA, which may provide potential reference value for clinical trials of TCM therapy for the treatment of RA.Key messagesLong noncoding RNA/circular RNA can work as the competitive endogenous RNA sponge and participate in the pathogenesis of rheumatoid arthritis.Traditional Chinese medicine and its agents have shown potential roles in the prevention and treatment of rheumatoid arthritis via competitive endogenous RNA.

The emerging role of circRNAs on skeletal muscle development in economical animals

CircRNAs are a novel type of closed circular molecules formed through a covalent bond lacking a 5'cap and 3' end tail, which mainly arise from mRNA precursor. They are widely distributed in plants and animals and are characterized by stable structure, high conservativeness in cells or tissues, and showed the expression specificity at different stages of development in different tissues. CircRNAs have been gradually attracted wide attention with the development of RNA sequencing, which become a new research hotspot in the field of RNA. CircRNAs play an important role in gene expression regulation. Presently, the related circRNAs research in the regulation of animal muscle development is still at the initial stage. In this review, the formation, properties, biological functions of circRNAs were summarized. The recent research progresses of circRNAs in skeletal muscle growth and development from economic animals including livestock, poultry and fishes were introduced. Finally, we proposed a prospective for further studies of circRNAs in muscle development, and we hope our research could provide new ideas, some theoretical supports and helps for new molecular genetic markers exploitation and animal genetic breeding in future.

Circular RNAs in atrial fibrillation: From bioinformatics analysis of circRNA-miRNA-mRNA network to serum expression

Atrial fibrillation (AF) is a common arrhythmia in clinical practice, and its incidence is increasing year by year, which seriously affects the survival and prognosis of patients. In recent years, circRNAs has played an important role in the diagnosis and treatment of AF. The purpose of this study was to search for differentially expressed circRNAs(DEcircRNAs) in the serum of AF patients by analyzing the expression profile of existing chips, combining bioinformatics technology and in vitro experiments, and to explore the regulatory mechanism of circRNAs in the occurrence and development of AF. By using the AF datasets in the Gene expression omnibus (GEO) database, serum samples of patients with AF were collected, and the expression level of selected circRNAs was verified by qPCR. We found that the expression of four circRNAs was increased in the serum of patients with AF, suggesting that these four DEcircRNAs may be used as auxiliary diagnostic markers for AF. Bioinformatics predicts the related signaling pathways that differentially expressed genes may regulate in the occurrence and development of AF, providing a new theoretical basis for the molecular mechanism of the occurrence of atrial fibrillation and auxiliary diagnostic targets.

Reduction of excessive unfolded protein response by 4-phenylbutyric acid may mitigate procymidone-induced testicular damage in mice by changing the levels of circRNA Scar and circZc3h4

Procymidone (PCM) exposure below the no-observed-effect level triggers changes in circRNA Scar and circZc3h4 and overactivation of the unfolded protein response (UPR) in mice, culminating in testicular injury. The 4-phenyl butyric acid (4-PBA) is known to stabilize proteins and reduce the UPR. This study employed an in vitro system in which mouse testes were cultured with 1 × 10-5 M PCM and varying concentrations (0, 20, 40, and 80 mM) of 4-PBA; 4-week-old male mice were subsequently treated with 100 mg/kg/d PCM (suspended in corn oil) and/or 100 mg/kg/d 4-PBA for 21 d, consecutively. The treatments were as follows: the negative control (NC) group was orally administered corn oil; the positive control (PC) group was orally administered PCM; the 4-PBA group was intraperitoneally injected with 4-PBA; the 4-PBA-I group was orally administered PCM and 4-PBA simultaneously; the 4-PBA-II group received daily administration of 4-PBA 24 h prior to PCM; and the 4-PBA-III group was intraperitoneally injected with 4-PBA for 7 d after 21 d of PCM administration. However, the 4-PBA intervention groups showed no considerable changes in the overall or testicular appearance of mice. In vitro, 4-PBA inhibited the PCM-induced testicular injury, with the most significant effect observed at 80 mM. In vivo, the 4-PBA-III group exhibited the best in vivo effects. Our findings indicate that 4-PBA conferred testicular protection by decreasing PCM-induced circRNA Scar, elevating circZc3h4, and suppressing UPR both in vitro and in vivo. It has been hypothesized that 4-PBA mitigates testicular damage by reducing excessive UPR levels.

Advances in Intercellular Communication Mediated by Exosomal ncRNAs in Cardiovascular Disease

Cardiovascular diseases are a leading cause of worldwide mortality, and exosomes have recently gained attention as key mediators of intercellular communication in these diseases. Exosomes are double-layered lipid vesicles that can carry biomolecules such as miRNAs, lncRNAs, and circRNAs, and the content of exosomes is dependent on the cell they originated from. They can be involved in the pathophysiological processes of cardiovascular diseases and hold potential as diagnostic and monitoring tools. Exosomes mediate intercellular communication, stimulate or inhibit the activity of target cells, and affect myocardial hypertrophy, injury and infarction, ventricular remodeling, angiogenesis, and atherosclerosis. Exosomes can be released from various types of cells, including endothelial cells, smooth muscle cells, cardiomyocytes, fibroblasts, platelets, adipocytes, immune cells, and stem cells. In this review, we highlight the communication between different cell-derived exosomes and cardiovascular cells, with a focus on the roles of RNAs. This provides new insights for further exploring targeted therapies in the clinical management of cardiovascular diseases.

EGCG-LYS Fibrils-Mediated CircMAP2K2 Silencing Decreases the Proliferation and Metastasis Ability of Gastric Cancer Cells in Vitro and in Vivo

Aberrant expression of circular RNAs (circRNAs) has been reported to play an important biological regulatory role in gastric cancer (GC). For the purpose of silencing cancer-related genes, a new approach for cancer treatment using nanocarriers to deliver siRNA has been proposed. In this study, abundantly expressed circMAP2K2 (hsa_circRNA_102415) is identified in GC cells. CircMAP2K2 regulates the PCBP1/GPX1 axis through proteasome-mediated degradation, which further mediates the activation of the AKT/GSK3β/epithelial-to-mesenchymal transition (EMT) signaling pathway and enhances the proliferation and metastatic ability of GC cells. To establish novel GC treatment, epigallocatechin-3-gallate-lysozyme (EGCG-LYS) fibrils are synthesized, and in vitro experiments demonstrate that EGCG-LYS has a higher siRNA delivery efficiency than Lipofectamine 2000 (lipo2000), which effectively silences the expression of circMAP2K2. Further studies show that EGCG-LYS carrying siRNA can successfully achieve lysosome escape, which allows it to be located in the cytoplasm to achieve post-transcriptional gene silencing. In addition, EGCG-LYS carrying si-circMAP2K2 has good circulating stability, excellent biosafety and antitumor ability in vivo. The EGCG-LYS fibrils delivery system provides a new tool and approach for the treatment of GC.

Circular RNAs-mediated angiogenesis in human cancers

Circular RNAs (circRNAs) as small non-coding RNAs with cell, tissue, or organ-specific expression accomplish a broad array of functions in physiological and pathological processes such as cancer development. Angiogenesis, a complicated multistep process driving a formation of new blood vessels, speeds up tumor progression by supplying nutrients as well as energy. Abnormal expression of circRNAs reported to affect tumor development through impressing angiogenesis. Such impacts are introduced as constant with different tumorigenic features known as "hallmarks of cancer". In addition, deregulated circRNAs show possibilities to prognosis and diagnosis both in the prophecy of prognosis in malignancies and also their prejudice from healthy individuals. In the present review article, we have evaluated the angiogenic impacts and anti-angiogenic managements of circRNAs in human cancers.

Downregulated circ_0001681 Predicts the Occurrence and Malignant Development of Lung Carcinoma via Negatively Modulating miR-567

OBJECTIVE

The screening and monitoring of lung adenocarcinoma (LUAD) is critical for its therapeutic efficiency. This study explored a novel biomarker of LUAD from the GSE146689 dataset and evaluated its function aiming to provide a potential therapeutic target for LUAD.

METHODS

There were 126 LUAD patients, 75 benign lung disease patients, and 57 healthy individuals enrolled in this study. circ_0001681 levels were evaluated by PCR, and its significance in the diagnosis and prognosis of LUAD was assessed by ROC and Cox regression analysis. The effect of circ_0001681 on LUAD cells was investigated by CCK8 and transwell assays.

RESULTS

Reduced circ_0001681 was observed in LUAD patients relative to benign lung disease patients and healthy individuals, which could discriminate LUAD patients. circ_0001681 downregulation was closely associated with the severity and malignancy of LUAD patients, and it also indicated the adverse prognosis of LUAD. In mechanism, circ_0001681 could negatively regulate miR-567, which was found to mediate the inhibitory effect of circ_0001681 on LUAD cell proliferation and motility.

CONCLUSION

Decreased circ_0001681 in LUAD served as a biomarker in tumor occurrence and development, which can be included in the formulation and adjustment of LUAD therapeutic strategy.