Non-coding RNAs in meningitis: Key regulators of immune response and inflammation.

Non-coding RNAs (ncRNAs) contain circular RNAs (circRNAs), long non-coding RNAs (lncRNAs), and micro-ribonucleic acids (miRNAs). These RNAs receive good functionality in modulation of gene expressions & cellular roles. Recent research is shedding light on their pivotal roles in the pathophysiology of inflammatory meningitis, such as viral, fungal, or bacterial infections. This review addresses the intricate roles of non-coding RNAs (ncRNAs) that transcribe code-independent mRNA and other biological elements that control inflammation and immunological events extant during meningitis. ncRNAs, acting on a myriad of immune cell development, cytokine production, pathogen recognition, and so forth, finely orchestrate the host's immune response. Although lncRNAs and circRNAs are associated with gene networks regulating immune responses, miRNAs can precisely modulate the expression of pro- and anti-inflammatory cytokines. Moreover, ncRNAs have unique expression patterns in disease states and are stable in bio-fluids; therefore, they can serve as specific molecular biomarkers for meningitis concerning the diagnosis and prognosis. It might also be helpful to target ncRNAs as a therapeutic strategy to impact immune regulation and inflammation. Here, we review the current knowledge of how ncRNAs function in meningitis and discuss adopted approaches and perspectives and their implications for therapeutic strategies.

The role of m6A modified circ0049271 induced by MNNG in precancerous lesions of gastric cancer.

Gastric cancer (GC) is a malignant cancer with the highest global rates of morbidity and death. Dietary factors have a close relationship with the occurrence of GC. Circular RNAs (circRNAs) and N6-methyladenine (m6A) are important factors in the onset and progression of GC and other malignancies. However, little is known about the role of circRNA m6A modifications in the occurrence and development of GC. Initially, a transformed malignant cell model generated by the chemical carcinogen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was established in this investigation. Furthermore, following exposure to MNNG, circ0049271 is substantially expressed in gastric epithelial cells (GES-1). Subsequent research revealed that the knockdown of circ0049271 prevented the epithelial-mesenchymal transition (EMT) as well as the migration, invasion, and proliferation of gastric epithelial cells induced by long-term exposure to MNNG. The opposite effects were observed when circ0049271 was overexpressed. Mechanistically, circ0049271 activates the TGFß/SMAD signaling pathway and has m6A modifications mediated by WTAP. Our findings indicate that circ0049271 promotes the occurrence of GC by regulating the TGFß/SMAD pathway, and WTAP may mediate the methylation of circ0049271 m6A. This study provides new insights into the regulation of circRNA-mediated m6A modifications and the discovery of early GC induced by dietary factors such as nitrite.

CircRNAs expression profile and potential roles of circRERE-PMN in pre-metastatic lungs.

The successful pulmonary metastasis of malignant cancer cells depends on the survival of circulating tumor cells in a distant and hostile microenvironment. The formation of a pre-metastatic niche (PMN) creates a supportive environment for subsequent metastasis. Circular RNAs (circRNAs) are increasingly acknowledged as crucial elements in the mechanisms of metastasis due to their stable structures and functions, making them promising early metastasis detection markers. However, the specific expression patterns and roles of circRNAs in the lungs before metastasis remain largely unexplored. Our research aims to chart the circRNA expression profile and assess their impact on the lung PMN. We developed a lung PMN model and employed comprehensive RNA sequencing to analyze the differences in circRNA expression between normal and pre-metastatic lungs. We identified 38 significantly different circRNAs, primarily involved in metabolism, apoptosis, and inflammation pathways. We then focused on one specific circRNA, circ:chr4:150406196 - 150406664 (circRERE-PMN), which exhibited a significant change in expression and was prevalent in myeloid-derived suppressor cells (MDSCs), alveolar epithelial cells, and macrophages within the pre-metastatic lung environment. CircRERE-PMN was found to potentially regulate apoptosis and the expression of cytokines and chemokines through its interaction with the downstream target HUR in alveolar epithelial cells. Overall, our study highlights the crucial role of circRNAs in the formation of lung PMNs, supporting their potential as diagnostic or therapeutic targets for lung metastasis.

Circular RNAs in programmed cell death: Regulation mechanisms and potential clinical applications in cancer: A review.

Circular RNAs (circRNAs) are a novel class of non-coding RNAs with covalently closed structures formed by reverse splicing of precursor mRNAs. The widespread expression of circRNAs across species has been revealed by high-throughput sequencing and bioinformatics approaches, indicating their unique properties and diverse functions including acting as microRNA sponges and interacting with RNA-binding proteins. Programmed cell death (PCD), encompassing various forms such as apoptosis, necroptosis, pyroptosis, autophagy, and ferroptosis, is an essential process for maintaining normal development and homeostasis in the human body by eliminating damaged, infected, and aging cells. Many studies have demonstrated that circRNAs play crucial roles in tumourigenesis and development by regulating PCD in tumor cells, showing that circRNAs have the potential to be biomarkers and therapeutic targets in cancer. This review aims to comprehensively summarize the intricate associations between circRNAs and diverse PCD pathways in tumor cells, which play crucial roles in cancer development. Additionally, this review provides a detailed overview of the underlying mechanisms by which circRNAs modulate various forms of PCD for the first time. The ultimate objective is to offer valuable insights into the potential clinical significance of developing novel strategies based on circRNAs and PCD for cancer diagnosis, prognosis, and treatment.

Novel role of circRNAs in the drug resistance of gastric cancer: regulatory mechanisms and future for cancer therapy.

Cancer, including gastric cancer, has become a serious disease that jeopardizes public life. Currently, the main treatment methods are surgery, radiation therapy, and chemotherapy. One of the primary causes of death for patients with gastric cancer is drug resistance. Several mechanisms of anticancer drugs resistance have been reported, including changes in drugs transport and metabolism, mutations in drug targets, changes in DNA repair systems, inhibition of cell apoptosis and autophagy, gastric cancer stem cells, invasion and migration. It is becoming more widely known that non-coding RNAs, like circRNAs, play a critical role in the resistance of drugs used to treat gastric cancer. CircRNAs have a unique structure and function that is related to gastric cancer resistance, cell proliferation, apoptosis, autophagy, DNA repair systems, migration, and invasion. A clear understanding of the molecular mechanism of circRNAs mediated the resistance of gastric cancer drugs will open a new window for the treatment and management of gastric cancer. Therefore, in this review, we will summarize the current mechanism of drug resistance, and finally discuss the molecular mechanism of circRNAs in regulating the development of drug resistance in gastric cancer.

[Corrigendum] Circular RNAs in osteosarcoma: An update of recent studies (Review).

Subsequently to the publication of the above review, the authors have contacted the Editorial Office to explain that the article was regrettably published containing a few errors. First, on p. 3, left­hand column, the '3. Functions of circRNAs in OS' section, line 23, the sentence here should have read as follows (changes shown in bold, where appropriate): 'Circ_0001649 has been reported as a sponge of various miRNAs that inhibit cell proliferation (62,83).' (i.e., mentioning 'Circ_0001649' twice was an error/oversight). Secondly, in the '4. Mechanisms of circRNAs in OS' section, paragraph 5, line 23 on p. 8, the four consecutive sentences that start on this line should have read as follows: 'Hsa_circ_0000190 is significantly downregulated in OS tissues and cell lines. This circRNA inhibits the Wnt/ß­catenin signaling pathway by sponging miR­767­5p, the target of which is TET1 (61). And hsa_circ_0002052 can sponge miR­1205, the target of which is adenomatosis polyposis coli 2 (APC2), a negative regulator of the Wnt/ß­catenin signaling pathway. Hence, hsa_circ_0000190 and hsa_circ_0002052 can function as inhibitors of the Wnt/ß­catenin signaling pathway by promoting TET1 and APC2 expression via miRNA sponging, ultimately resulting in the delayed development of OS (50,61).' (i.e., the first sentence was corrected to read 'Hsa_circ_0000190' and 'hsa_circ_0000190' was added to the fourth sentence, and ref. 61 was added to the second sentence in this section, and included with ref. 50 at the end of the fourth sentence). Thirdly (and finally), changes were required to both Fig. 3 and its accompanying legend, and these are featured on the next page; essentially, 'CircRNA CDR1as (47)' should not have been included in the Fig. 3 legend as this circRNA is not described in the figure, and some changes have been made to the figure itself in terms of wrongly placed lines and arrows. The authors are grateful to the Editor of International Journal of Oncology for allowing them this opportunity to publish this Corrigendum, and all the authors agree with its publication. Furthermore, the authors apologize to the readership for any inconvenience caused. [International Journal of Oncology 63: 123, 2023; DOI: 10.3892/ijo.2023.5571].

Advanced Insights into Competitive Endogenous RNAs (ceRNAs) Regulated Pathogenic Mechanisms in Metastatic Triple-Negative Breast Cancer (mTNBC).

Triple-negative breast cancer is aggressive and challenging to treat because of a lack of targets and heterogeneity among tumors. A paramount factor in the mortality from breast cancer is metastasis, which is driven by genetic and phenotypic alterations that drive epithelial-mesenchymal transition, stemness, survival, migration and invasion. Many genetic and epigenetic mechanisms have been identified in triple-negative breast cancer that drive these metastatic phenotypes; however, this knowledge has not yet led to the development of effective drugs for metastatic triple-negative breast cancer (mTNBC). One that may not have received enough attention in the literature is post-translational regulation of broad sets of cancer-related genes through inhibitory microRNAs and the complex competitive endogenous RNA (ceRNA) regulatory networks they are influenced by. This field of study and the resulting knowledge regarding alterations in these networks is coming of age, enabling translation into clinical benefit for patients. Herein, we review metastatic triple-negative breast cancer (mTNBC), the role of ceRNA network regulation in metastasis (and therefore clinical outcomes), potential approaches for therapeutic exploitation of these alterations, knowledge gaps and future directions in the field.

Significance of VLPs in Vlp-circRNA vaccines: a vaccine candidate or delivery vehicle?

Circular RNAs (circRNAs) are a class of single-stranded RNAs with a closed loop lacking 5' and 3' ends. These circRNAs are translatable and, therefore, have a potential in developing vaccine. CircRNA vaccines have been shown to be more stable, safe, easy to manufacture and scale-up production when compared to mRNA vaccines. However, these vaccines also suffer from several drawbacks such as low circularization efficiency for longer RNA precursor and usage of lipid nano particles (LNPs) in their delivery. LNPs have been shown to require large amounts of RNA due to their indirect delivery from endosome to cytosol. Besides, individual components of LNPs provide reactogenicity. Usage of virus like particles (VLPs) can improve the increased production and targeted delivery of circRNA vaccines and show no reactogenicity. Moreover, VLPs has also been used to produce vaccines against several diseases such as hepatitis C virus (HCV) etc. In this article, we will discuss about the methods used to enhance synthesis or circularization efficiency of circRNA. Moreover, we will also discuss about the significance of VLPs as the delivery vehicle for circRNA and their possible usage as the dual vaccine.

The role of circRNAs and miRNAs in drug resistance and targeted therapy responses in breast cancer.

MicroRNAs (miRNAs) are small non-coding RNAs comprising 19-24 nucleotides that indirectly control gene expression. In contrast to other non-coding RNAs (ncRNAs), circular RNAs (circRNAs) are defined by their covalently closed loops, forming covalent bonds between the 3' and 5' ends. circRNAs regulate gene expression by interacting with miRNAs at transcriptional or post-transcriptional levels. Accordingly, circRNAs and miRNAs control many biological events related to cancer, including cell proliferation, metabolism, cell cycle, and apoptosis. Both circRNAs and miRNAs are involved in the pathogenesis of diseases, such as breast cancer. This review focuses on the latest discoveries on dysregulated circRNAs and miRNAs related to breast cancer, highlighting their potential as biomarkers for clinical diagnosis, prognosis, and chemotherapy response.

Identification and functional characterization of differentially expressed circRNAs in high glucose treated endothelial cells: Construction of circRNA-miRNA-mRNA network.

Background: Endothelial dysfunction is a complication of diabetes mellitus (DM), characterized by impaired endothelial function in both microvessels and macrovessels, closely linked to atherosclerosis (AS). Endothelial dysfunction, characterized by impaired endothelial cell (EC) function, is a pivotal factor in AS and DM. Circular RNAs (circRNAs) are endogenous non-coding RNAs that can act as competing endogenous RNAs (ceRNAs) and regulate gene expression. However, the role of circRNAs in ECs dysfunction and AS under high glucose (HG) condition remains elusive. Methods: We performed high-throughput sequencing to identify differentially expressed (DE) circRNAs in human umbilical vein endothelial cells (HUVEC) exposed to HG, one risk factors of endothelial dysfunction and AS. We then validated eight candidate circRNAs by qRT-PCR and functional analysis, directing our attention to hsa_circ_0122319. Moreover, microarray analysis identified the differential expression profiles of miRNAs and mRNAs regulated by hsa_circ_0122319. Subsequently, the construction of the ceRNAs network employed bioinformatic analysis and Cytoscape software. Furthermore, the role of the PI3K-Akt signaling pathway in regulating ceRNAs was evaluated. Results: We detected 917 DE circRNAs in HG treated HUVEC. The parental genes of these circRNAs were enriched in cell cycle, cellular senescence and endocytosis related pathways. The differential expression of hsa_circ_0122319 was confirmed to be most obvious at the cellular level and in clinical samples by qPCR experiments. After overexpression of hsa_circ_0122319, 49 DE miRNAs and 459 DE mRNAs were identified using microarray analysis. Subsequently, a ceRNAs network was constructed, comprising hsa_circ_0122319, 8 miRNAs, and 41 mRNAs. Conclusion: In summary, our study delves into the role of circRNAs in endothelial dysfunction associated with DM and AS. Through high-throughput sequencing and validation, we identified hsa_circ_0122319 as a pivotal regulator of ECs function under HG conditions. It also showed that hsa_circ_0123319 has the potential to serve as a biomarker for DM and its vascular complications, and provides new evidence for future exploration of the intricate molecular mechanisms of endothelial dysfunction in the progression of DM and AS.

The role of circular RNA targeting IGF2BPs in cancer-a potential target for cancer therapy.

Circular RNAs (circRNAs) are an interesting class of conserved single-stranded RNA molecules derived from exon or intron sequences produced by the reverse splicing of precursor mRNA. CircRNAs play important roles as microRNA sponges, gene splicing and transcriptional regulators, RNA-binding protein sponges, and protein/peptide translation factors. Abnormal functions of circRNAs and RBPs in tumor progression have been widely reported. Insulin-like growth factor-2 mRNA-binding proteins (IGF2BPs) are a highly conserved family of RBPs identified in humans that function as post-transcriptional fine-tuners of target transcripts. Emerging evidence suggests that IGF2BPs regulate the processing and metabolism of RNA, including its stability, translation, and localization, and participate in a variety of cellular functions and pathophysiology. In this review, we have summarized the roles and molecular mechanisms of circRNAs and IGF2BPs in cancer development and progression. In addition, we briefly introduce the role of other RNAs and IGF2BPs in cancer, discuss the current clinical applications and challenges faced by circRNAs and IGF2BPs, and propose future directions for this promising research field.

Whole-transcriptome sequencing analysis to identify key circRNAs, miRNAs, and mRNAs in the development of yak testes.

BACKGROUND: The Testis is an important reproductive organ in male mammals and the site for spermatogenesis, androgen synthesis, and secretion. Non-coding RNAs (ncRNAs) play an important regulatory role in various biological processes. However, the regulatory role of ncRNAs in the development of yak testes and spermatogenesis remains largely unclear. RESULT: In this study, we compared the expression profiles of circular RNAs (circRNAs), microRNAs (miRNAs), and messenger RNAs (mRNAs) in yak testicular tissue samples collected at 6 months (Y6M), 18 months (Y18M), and 4 years (Y4Y). Using RNA sequencing (RNA-Seq), we observed a significant difference in the expression patterns of ncRNAs in the samples collected at different testicular development stages. Twenty-two differentially expressed (DE) circRNAs, 69 DE miRNAs, and 64 DE mRNAs were detected in Y6M, Y18M, and Y4Y testicular samples, respectively. The results of gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that the source genes of DE circRNAs, predicted target genes of DE miRNAs, and DE mRNAs were specifically associated with signaling pathways and GO terms that were related to sperm synthesis, sperm vitality, and testicular development, such as cell cycle, Wnt signaling pathway, MAPK signaling pathway, GnRH signaling pathway, and spermatogenesis. The analysis of the circRNA-miRNA-mRNA network revealed that some DE ncRNAs, including miR-574, miR-449a, CDC42, and CYP11A1, among others, may be involved in testicular spermatogenesis. Concurrently, various circRNA-miRNA interaction pairs were observed. CONCLUSION: Our findings provide a database of circRNAs, miRNAs, and mRNAs expression profiles in testicular tissue of yaks at different developmental stages and a detailed understanding of the regulatory network of ncRNAs in yak testicular development and provide data that can help elucidate the molecular mechanisms underlying yak testicular development.

CircCOCH plays a critical role in Hepatocellular carcinoma through modulating miR-450a and activating PI3K/mTOR pathway.

Hepatocellular carcinoma (HCC) is a primary liver cancer with high pathogenicity and extremely poor prognosis. The role of circular RNAs (circRNAs) in HCC carcinogenesis and progression remains to be determined. Based on the analysis of HCC-related databases, as well as the expression analysis and identification of 25 HCC patient tissues and HCC cell lines, we found that the hsa_circ_0031431 (circCOCH) is significantly highly expressed in HCC tissues and cell lines. High circCOCH expression is associated with enhanced tumor proliferation and metastasis, and knocking down circCOCH can inhibit the growth of HCC in vivo and in vitro. Mechanistic studies show that circCOCH upregulates the expression of epidermal growth factor receptor (EGFR) through sponge miR-450a, thereby activating the Phosphoinositide 3-kinases (PI3Ks) cell pathway to promote HCC proliferation and metastasis. Futhermore, we found that IGF2BP3 mediates the biogenesis of circCOCH. The present study provides innovative insights into the role of circRNAs in the etiology of HCC carcinogenesis and might serve as a new promising therapeutic target for HCC.

Circular RNAs in lung cancer: implications for preventing therapeutic resistance.

LC is one of the most common malignant tumours that often presents with no distinct symptoms in the early stages, leading to late diagnoses when patients are at an advanced stage and no longer suitable for surgical treatment. Although adjuvant treatments are available, patients frequently develop tolerance to these treatments over time, resulting in poor prognoses for patients with advanced LC. Recently, circular RNAs (circRNAs), a type of non-coding RNA, have gained significant attention in LC research. Owing to their unique circular structure, circRNAs are highly stable within cells. This review systematically summarises the expression, characteristics, biological functions, and molecular regulatory mechanisms of circRNAs involved in therapy resistance as well as the potential applications in early diagnosis and gene targeting therapy in LC.

Circ_BBS9 as an early diagnostic biomarker for lung adenocarcinoma: direct interaction with IFIT3 in the modulation of tumor immune microenvironment.

Background: Introduction: Circular RNAs (circRNAs) have been identified as significant contributors to the development and advancement of cancer. The objective of this study was to examine the expression and clinical implications of circRNA circ_BBS9 in lung adenocarcinoma (LUAD), as well as its potential modes of action. Methods: The expression of Circ_BBS9 was examined in tissues and cell lines of LUAD through the utilization of microarray profiling, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot analysis. In this study, we assessed the impact of circ_BBS9 on the proliferation of LUAD cells, as well as its influence on ferroptosis and tumor formation. To analyze these effects, we employed CCK-8 assays and ferroptosis assays. The identification of proteins that interact with Circ_BBS9 was achieved through the utilization of RNA pull-down and mass spectrometry techniques. A putative regulatory network comprising circ_BBS9, miR-7150, and IFIT3 was established using bioinformatics study. The investigation also encompassed the examination of the correlation between the expression of IFIT3 and the invasion of immune cells. Results: Circ_BBS9 was significantly downregulated in LUAD tissues and cell lines. Low circ_BBS9 expression correlated with poor prognosis. Functional experiments showed that circ_BBS9 overexpression inhibited LUAD cell proliferation and promoted ferroptosis in vitro and suppressed tumor growth in vivo. Mechanistically, circ_BBS9 was found to directly interact with IFIT3 and regulate its expression by acting as a sponge for miR-7150. Additionally, IFIT3 expression correlated positively with immune infiltration in LUAD. Conclusion: Circ_BBS9 has been identified as a tumor suppressor in lung adenocarcinoma (LUAD) and holds promise as a diagnostic biomarker. The potential mechanism of action involves the modulation of ferroptosis and the immunological microenvironment through direct interaction with IFIT3 and competitive binding to miR-7150. The aforementioned findings offer new perspectives on the pathophysiology of LUAD and highlight circ_BBS9 as a potentially valuable target for therapeutic interventions.

An updated resource for the detection of protein-coding circRNA with CircProPlus.

Protein-encoding circular RNAs (circRNAs) are newly identified RNA molecules characterized by intense interaction with translating ribosome. Emerging evidence has implicated physiological and pathological significance of these non-canonical RNAs, yet a large body of them remains unidentified. Due to limited tools at hand, we developed CircProPlus, an automated computational pipeline for de novo detection of translated circRNAs. In comparison to previously established CircPro, CircProPlus adjusts the overall workflow and integrates more robust implements for achieving easier accessibility, higher flexibility and productivity. In present study, we tested the performance of CircProPlus when using different circRNA-detecting implements (i.e., CIRI2, CirComPara2) in the evaluation of coding ability of circRNAs. Results showed that CirComPara2, a state-of-the-art algorithm, consistently outperformed CIRI2 when coupled with CircProPlus in testing real data collected from different RNA libraries and species, which highlighted its potency in data mining of circRNAs with protein-coding potential.

Non-coding RNAs in hepatocellular carcinoma metastasis: Remarkable indicators and potential oncogenic mechanism.

Non-coding RNAs (ncRNAs), as key regulators involving in intercellular biological processes, are more prominent in many malignancies, especially for hepatocellular carcinoma (HCC). Herein, we conduct a comprehensive review to summarize diverse ncRNAs roles in HCC metastatic mechanism. We focus on four signaling pathways that predominate in HCC metastatic process, including Wnt/ß-catenin, HIF-1α, IL-6, and TGF-ß pathways. MicroRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) employed different mechanisms to participate in the regulation of the key genes in these pathways, typical as interaction with DNA to control transcription, with RNA to control translation, and with protein to control stability. Therefore, ncRNAs may become potential biomarkers and therapeutic targets for HCC metastasis.

Circular RNAs in tumor immunity and immunotherapy.

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

Long non-coding and circular RNAs in osteoporosis: Translation to clinical practice.

Non-coding RNAs (ncRNAs) belong to a class of untranslated nucleic acids involved in regulation of gene expression. ncRNAs are categorized as small (<200 ribonucleotides in length), i.e., microRNAs (miRNAs), and long ncRNAs (lncRNAs) (200 to thousands of ribonucleotides in length) and circular RNAs (circRNAs). In contrast to miRNAs, the roles of lncRNAs in general and circRNAs in bone metabolism specifically are not well understood. As such, a comprehensive understanding of these RNA species in bone turnover could be of great value in the development of new diagnostic tools and therapeutic targets. Unfortunately, measurement of these unique RNAs lacks standardization, a component critical to clinical translation. This review examines the potential role of lncRNA and circRNA as bone biomarkers, the need for validated and standardized measurement and challenges thereof.

A Comprehensive Insight and In Silico Analysis of CircRNAs in Hepatocellular Carcinoma: A Step toward ncRNA-Based Precision Medicine.

Circular RNAs (circRNAs) are cardinal players in numerous physiological and pathological processes. CircRNAs play dual roles as tumor suppressors and oncogenes in different oncological contexts, including hepatocellular carcinoma (HCC). Their roles significantly impact the disease at all stages, including initiation, development, progression, invasion, and metastasis, in addition to the response to treatment. In this review, we discuss the biogenesis and regulatory functional roles of circRNAs, as well as circRNA-protein-mRNA ternary complex formation, elucidating the intricate pathways tuned by circRNAs to modulate gene expression and cellular processes through a comprehensive literature search, in silico search, and bioinformatics analysis. With a particular focus on the interplay between circRNAs, epigenetics, and HCC pathology, the article sets the stage for further exploration of circRNAs as novel investigational theranostic agents in the dynamic realm of HCC.