CircRNA in cancer: Fundamental mechanism and clinical potential

Circular RNA Circ_0002762 promotes cell migration and invasion in cervical squamous cell carcinoma via activating RelA/nuclear factor kappa B (Nf-kB) signalling pathway

Cervical cancer is a leading cause of cancer-related deaths, with cervical squamous cell carcinoma (CSCC) accounting for a majority of cases. Circular RNAs (circRNAs) have been repeatedly suggested as crucial effectors in modulating the development of multiple malignancies. The expression of circ_0002762 was predicted to be high in CSCC tissues in GEO dataset, but the functional role and underlying regulatory mechanism of circ_0002762 in CSCC was unclear. By series of functional assays and mechanism assays, supported by bioinformatics analysis, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) analysis and western blot assays, we identified that circ_0002762 aberrantly up-regulated in CSCC, promoting CSCC cell migration and invasion. Mechanically, circ_0002762 was transcriptionally activated by Fork head box A1 (FOXA1). Moreover, the involvement of nuclear factor kappa B (NF-kB) signalling in circ_0002762 regulation mechanism in CSCC cells was ascertained. Additionally, circ_0002762, predominantly accumulated in cell cytoplasm, was proved to recruit Mov10 RISC complex RNA helicase (MOV10) to enhance RelA mRNA stability, thus affecting CSCC cell migration and invasion. In summary, FOXA1-mediated circ_0002762 up-regulation could enhance the migratory and invasive abilities of CSCC cells via the MOV10/RelA/NF-kB pathway.

Circular RNAs in gynecological cancer: From molecular mechanisms to clinical applications (Review)

Circular RNAs (circRNAs) have emerged as promising biomarkers and therapeutic targets in gynecological cancer. The present review explored developments in circRNA research in ovarian, endometrial and cervical cancer. circRNA biogenesis, functions and roles in cancer pathogenesis have been discussed, focusing on their potential as diagnostic and prognostic markers. Furthermore, circRNAs mechanisms of action, including miRNA sponging, protein scaffolding and peptide encoding were examined, highlighting specific circRNAs implicated in each cancer type and their clinical significance. The unique properties of circRNAs, such as stability and tissue-specific expression, make them ideal candidates for biomarker development. By synthesizing the currently available literature and identifying future research directions, the present review underscored circRNAs potential to improve gynecological cancer management through novel diagnostic tools, prognostic markers and targeted therapies.

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

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

CircST6GALNAC6 Inhibits Glycolysis of Bladder Cancer by Regulating PRKN/HK1 Signaling Pathway

Bladder cancer (BCa) is an aggressive malignancy of urinary system. Aerobic glycolysis refers to the phenomenon wherein cancer cells increase glucose consumption and produce lactic acid. Our study focused on the role and mechanism of circST6GALNAC6 in BCa glycolysis. The 24 h glucose intake was detected using flow cytometry. Lactic acid and ATP were detected in BCa cells utilizing commercially provided kits. Extracellular acidification rate was measured using Seahorse XF-96p Extracellular Flux Analyzer. Cell proliferation was determined using colony formation assay. RNA immunoprecipitation and co-immunoprecipitation experiments were adopted to validate molecular interactions. BALB/C nude mice were utilized to establish xenograft tumor model. CircST6GALNAC6 was decreased in BCa cells, and overexpression of circST6GALNAC6 inhibited glycolysis and proliferation of BCa cells. Additionally, overexpression of circST6GALNAC6 promoted the degradation of glycolytic regulatory protein HK1 and decreased its expression, and PRKN facilitated ubiquitination-related degradation of HK1. CircST6GALNAC6 enhanced the mRNA stability and expression of PRKN by recruiting FUS. Furthermore, the inhibitory impact of circST6GALNAC6 overexpression on glycolysis in BCa cells was reversed by PRKN knockdown. Finally, overexpression of circST6GALNAC6 suppressed tumor growth through increasing PRKN in nude mice. CircST6GALNAC6 suppressed glycolysis in BCa through FUS/PRKN/HK1 axis. Targeting circST6GALNAC6 holds promise as a novel approach for treating BCa.

CircDIAPH1 Promotes Liver Metastasis and Development of Colorectal Cancer by Initiation of CEACAM6 Expression

Liver metastasis is a critical factor influencing the 5-year survival rate in colorectal cancer (CRC). However, the biological function of most circRNAs in liver metastasis of CRC is still unknown. In this study, we identified differentially expressed circRNAs associated with liver metastasis (LM-DE-circRNAs). A total of 247 LM-DE-circRNAs were identified, and crucial signaling pathways, including the regulation of actin cytoskeleton, were significantly enriched, featuring six LM-DE-circRNAs. Notably, circDIAPH1 (hsa_circ_0074323), with the highest AUC value, emerged as a potential biomarker for CRC liver metastasis (CRLM). Functional assays following circDIAPH1 knockdown demonstrated induced apoptosis, suppressed proliferation, reduced metastasis, and invasion in CRC cell lines in vitro. The circDIAPH1 knockdown attenuated tumor growth in a cell-derived xenograft model. Furthermore, circDIAPH1 knockdown lessened the liver metastasis. Transcriptome profiling revealed that CEACAM6 was the most downregulated gene while circDIAPH1 was knocked down, and possesses high expression value in CRC. Most importantly, we found that circDIAPH1 recruited transcription factor FOXA1 to bind in the promoter region of CEACAM6 and initiated CEACAM6 expression. Additionally, the study identified the transcription factor BRD4 as a regulator of circDIAPH1 expression in CRC. In conclusion, this study reveals that circDIAPH1 recruits FOXA1 to initiate CEACAM6 expression, promoting liver metastasis and development of CRC.

N6-methyladenosine-modified circQKI inhibits prostate cancer docetaxel-sensitivity via miR-188-3p/Beclin-1 pathway

BACKGROUND

Docetaxel (DTX) is used in the first-line chemotherapy for advanced castration-resistant prostate cancer (CRPC), but resistance remains a major clinical challenge. Circular RNAs (circRNAs) play critical roles in DTX resistance. This study aimed to investigate the mechanism of a novel circRNA, circQKI, in DTX resistance and its regulatory network in CRPC.

METHODS

DTX-resistant cell lines (PC3/DR and 22RV1/DR) were established, and circQKI's circular structure was validated by Sanger sequencing. CircQKI expression was modulated via siRNA knockdown and overexpression plasmids. Cell viability, apoptosis, and colony formation were assessed by CCK-8, flow cytometry, and clonogenic assays. The interaction between circQKI and miR-188-3p was verified by dual-luciferase reporter, RIP, and RNA pull-down. Autophagy activation was analyzed via Western blot and TEM. Subcutaneous xenograft models evaluated in vivo drug resistance. M6A modification was investigated through m6A RIP-PCR, METTL3/IGF2BP2 knockdown, and stability assays.

RESULTS

CircQKI was significantly upregulated in resistant cells and promoted DTX resistance by sponging miR-188-3p, thereby enhancing Beclin-1 expression and autophagy activation. Inhibiting Beclin-1 or co-treatment with chloroquine (CQ) partially restored DTX sensitivity. Mechanistically, METTL3-mediated m6A modification stabilized circQKI via IGF2BP2 recognition, leading to its accumulation in resistant cells. In vivo studies confirmed that circQKI overexpression reduced tumor sensitivity to DTX by enhancing autophagy.

CONCLUSION

circQKI drives DTX resistance via the miR-188-3p/Beclin-1 axis and autophagy activation, with its expression regulated by METTL3-dependent m6A modification and IGF2BP2. Targeting circQKI or autophagy pathways may offer novel therapeutic strategies to overcome DTX resistance in prostate cancer.

Exosomal circ_0001583 Drives Glioblastoma Cell Advancement Through the miR-647/CKAP2L Pathway

Our study aimed to explore the involvement of circ_0001583 in the progression of glioblastoma (GBM). The expression levels of CircRNA in GBM were examined using the GEO database, and quantification of circ_0001583 levels was performed through qRT-PCR in both GBM tissues and cell lines. Survival analysis was conducted using Kaplan-Meier plots. The effects of circ_0001583 knockdown on cell proliferation, invasion, and glycolysis were evaluated through functional assays and measurements of glycolytic activity. Bioinformatics and reporter assays revealed that miR-647 serves as a target for circ_0001583. Tumorigenesis following circ_0001583 knockdown was investigated in a nude mouse model utilizing U251 cells. Additionally, a co-culture system with normal human astrocytes (NHAs) and GBM-conditioned medium was employed to study circ_0001583 expression and its influence on cell proliferation. The presence of circ_0001583 in normal human astrocytes was assessed using PKH67 labeling and immunofluorescence techniques. Bioinformatics analyses revealed a notable increase in the expression of circ_0001583 in GBM, correlating with metastasis. The inhibition of circ_0001583 expression led to decreased viability, proliferation, and invasive potential of GBM cells. It was found that circ_0001583 targets miR-647, which is downregulated in GBM. Silencing circ_0001583 resulted in elevated levels of miR-647. CKAP2L, a target of miR-647, showed an overexpression in GBM cases. Additionally, a positive relationship was established between circ_0001583 and CKAP2L, contrasting with a negative association with miR-647. An increase in miR-647 expression led to a decrease in CKAP2L protein levels. Rescue assays further validated that circ_0001583 influences the functions of GBM cells through the miR-647/CKAP2L pathway. In vivo investigations demonstrated that the knockdown of circ_0001583 resulted in retarded tumor growth, enhanced levels of miR-647, and diminished expression of Ki-67, CKAP2L, HK2, and LDHA within tumors. Moreover, co-culture studies involving GBM-conditioned medium demonstrated an upregulation of circ_0001583 in NHAs, which promoted cell proliferation. Our data collectively suggest that exosomal circ_0001583 promotes glioblastoma progression via the miR-647/CKAP2L pathway.

Comprehensive insights into circular RNAs, miRNAs, and lncRNAs as biomarkers in retinoblastoma

Retinoblastoma (RB) is a common and potentially lethal cancer that primarily affects young children worldwide, with survival rates significantly varying between high- and low-income countries. This review aims to identify essential diagnostic markers for early diagnosis by investigating the molecular pathways associated with RB. The prevalence of RB cases is notably concentrated in Asia and Africa, contributing to a global survival rate estimate of less than 30%. Current management strategies involve complex, individualized treatment plans that consider cultural nuances, genetic abnormalities, staging, and the availability of medical resources. Recent studies suggest that circular RNAs (circRNAs) may serve as predictive and diagnostic biomarkers in the etiology of RB. This review examines the roles of long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circRNAs in RB, with the goal of improving survival rates, particularly in low- and middle-income countries. A deeper understanding of the molecular pathways of RB may facilitate the development of personalized treatment plans and targeted therapies. Elevated expression of circRNAs has been observed in most patient cases, and studies indicate that reducing specific circRNA production can inhibit tumor cell development and progression. Investigating the roles and mechanisms of circular RNAs in RB holds promise for future treatment approaches.

Decoding the regulatory roles of circular RNAs in cardiac fibrosis

Cardiovascular diseases (CVDs) are the primary cause of death globally. The evolution of nearly all types of CVDs is characterized by a common theme: the emergence of cardiac fibrosis. The precise mechanisms that trigger cardiac fibrosis are still not completely understood. In recent years, a type of non-coding regulatory RNA molecule known as circular RNAs (circRNAs) has been reported. These molecules are produced during back splicing and possess significant biological capabilities, such as regulating microRNA activity, serving as protein scaffolds and recruiters, competing with mRNA, forming circR-loop structures to modulate transcription, and translating polypeptides. Furthermore, circRNAs exhibit a substantial abundance, notable stability, and specificity of tissues, cells, and time, endowing them with the potential as biomarkers, therapeutic targets, and therapeutic agents. CircRNAs have garnered growing interest in the field of CVDs. Recent investigations into the involvement of circRNAs in cardiac fibrosis have yielded encouraging findings. This study aims to provide a concise overview of the existing knowledge about the regulatory roles of circRNAs in cardiac fibrosis.

CircHOMER1 promotes silica-induced pulmonary fibrosis by binding to HuR and stabilizing NOX4 mRNA

BACKGROUND

Silicosis, one of the serious occupational diseases, is mainly manifested by pulmonary fibrosis induced by long-term exposure to silica particles in workplace. Evidence demonstrates that circular RNAs (circRNAs) are interesting regulators of pulmonary fibrosis process. So, further elucidation of the role of circRNAs may provide a new perspective into mechanisms driving pulmonary fibrosis and silicosis.

METHODS

The characteristics of circRNA homer scaffold protein 1 (hsa_circ_0006916, circHOMER1) was assessed using Actinomycin D, RNase R, and nucleoplasmic separation assay. The histopathological examination and Enzyme-linked immunosorbent assay (ELISA) were used to confirm circHOMER1 function in mouse lung tissues under silica particle exposure. The expression of circHOMER1, human antigen R (HuR) and NADPH oxidase 4 (NOX4) was identified by western blot or RT-qPCR assay. The RNA immunoprecipitation (RIP) assay and plasmid co-transfection were used to analyze the interaction between circHOMER1, HuR and NOX4.

RESULTS

We confirmed an upregulated circHOMER1 in silicosis fibrosis. Functional assays showed that the knockdown of circHOMER1 suppressed the viability of fibroblasts and the production of fibrotic molecules and alleviated the histology fibrotic changes in lung tissues from mouse exposed to silica particles. Mechanistically, we found that circHOMER1 directly bound to HuR and promoted its protein expression in fibroblasts. And, circHOMER1 further regulated HuR/NOX4 signaling axis through HuR to stabilize NOX4 mRNA, which enhanced the production of reactive oxygen species (ROS), thereby promoting the silicosis fibrosis process.

CONCLUSION

This study revealed the role of circHOMER1 in silica-induced pulmonary fibrosis, suggesting that the inhibition of circHOMER1 may be a potential therapeutic approach to relieve the pathological process of silicosis.

Noncanonical circRNA biogenesis driven by alpha and gamma herpesviruses

Herpesviruses require the host transcriptional machinery, inducing significant changes in gene expression to prioritize viral transcripts. We examined alpha- and gamma-herpesvirus alterations to a type of alternative splicing, namely circular RNA (circRNA) synthesis. We developed "Circrnas in Host And viRuses anaLysis pIpEline" (CHARLIE) to facilitate viral profiling. This method identified thousands of back-splicing variants, including circRNA common to lytic and latent phases of infection. Ours is the first report of Herpes Simplex Virus-1 circRNAs, including species derived from ICP0 and the latency-associated transcript. We characterized back-splicing cis- and trans-elements, and found viral circRNAs resistant to spliceosome perturbation and lacking canonical splice donor-acceptors. Subsequent loss-of-function studies of host RNA ligases (RTCB, RLIG1) revealed instances of decreased viral back splicing. Using eCLIP and 4sU-Sequencing, we determined that the KSHV RNA-binding protein, ORF57, enhanced synthesis for a subset of viral and host circRNAs. Our work explores unique splicing mechanisms driven by lytic infection, and identifies a class of transcripts with the potential to function in replication, persistence, or tumorigenesis.

CircITGA7 overexpression suppresses HCC progression via miR-330/BCL11B axis regulation

As a kind of prevalent malignancy globally, hepatocellular carcinoma (HCC) is characterized by significant morbidity and mortality due to the difficulties in early diagnosis and limited treatment options. Circular RNAs (circRNAs) are a type of circular single-stranded RNA molecule formed by the back-splicing of the 5' end and the 3' end of linear RNA, possessing multiple biological functions. In recent years, numerous reports have demonstrated that circRNAs are potential biomarkers and therapeutic targets for HCC. In this study, we found that circITGA7 is significantly downregulated in HCC tissue compared to adjacent non-tumor tissue. Functional experiments such as CCK8, EdU, colony formation and wound healing assays proved that overexpression of circITGA7 can effectively inhibit the proliferation, migration and invasion of HCC cells. Further research found that circITGA7 can inhibit miR-330 to release BCL11B expression, thereby promoting P53 expression, blocking the cell cycle and promoting apoptosis in HCC cells. In addition, circITGA7 can impede the proliferation of HCC cells in vivo. Therefore, circITGA7 is a potential biomarker for the diagnosis of HCC development and a potential target for the treatment of HCC.

CircCENPM serves as a CeRNA to aggravate nasopharyngeal carcinoma metastasis and stemness via enhancing BMI1

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a malignant head and neck cancer with high mortality and dismal prognosis. Emerging research have disclosed that circRNAs are crucial gene expression regulators engaged in tumor advancement. This work aspired to identify novel oncogenic circRNA driving NPC progression.

METHODS

Bioinformatics analysis was performed to explore and predict underlying circRNA and downstream targets. Luciferase reporter assay was executed to check the binding relationship between these genes. Cell function tests were conducted using CCK-8, would healing, and flow cytometry. The stemness markers CD133, Nanog and Oct4 was detected via western blot.

RESULTS

CircCENPM was notably enhanced in NPC. Silencing of circCENPM suppressed NPC cell growth, migration, and stemness in vitro, simultaneously impeded tumorigenesis of NPC in vivo. Moreover, circCENPM could interact with miR-362-3p, whereas miR-362-3p inhibitor apparently reversed the mitigated growth and stemness induced by circCENPM knockdown in NPC cells. Furthermore, BMI1 was identified to be the downstream target of miR-362-3p, and BMI1 introduction partially offset the anti-tumor function of miR-362-3p in NPC cells.

CONCLUSION

CircCENPM functioned as a carcinogenic driver and facilitated NPC growth and stemness via miR-362-3p/BMI1 regulatory network, which provided a potential biomarker and attractive target for NPC intervention and treatment.

CircKIAA0182-YBX1 Axis: A Key Driver of Lung Cancer Progression and Chemoresistance

Lung cancer, particularly non-small cell lung cancer (NSCLC), remains a leading cause of cancer-related mortality. Resistance to platinum-based chemotherapy, such as cisplatin, significantly limits treatment efficacy. Circular RNAs (circRNAs) have emerged as key regulators of cancer progression and chemotherapy resistance due to their stable structure, which protects them from degradation. In this study, we focus on circKIAA0182, a circRNA identified as highly expressed in cisplatin-resistant NSCLC cells through profiling. We explore its role in cell proliferation, migration, invasion, apoptosis, and cisplatin resistance. Our findings show that circKIAA0182 promotes cisplatin resistance and tumor progression in NSCLC, in vitro and in vivo. Furthermore, we discovered that circKIAA0182 may interact with the RNA-binding protein YBX1, potentially mediating its oncogenic and cisplatin-resistant functions. The biological role of circKIAA0182 presents a promising target for developing therapeutic strategies to overcome NSCLC progression and cisplatin resistance.

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

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

circEIF3I Promotes Colorectal Cancer Metastasis by Regulating the miR-328-3p/NCAPH Axis

Colorectal cancer (CRC) is the most common gastrointestinal malignancy, with its recurrence and metastasis significantly affecting patient survival. Circular RNAs (circRNAs), a novel class of noncoding RNAs, have emerged as crucial contributors to CRC pathogenesis. However, the role of circEIF3I in CRC metastasis remains unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied to assess circEIF3I, microRNA (miR)-328-3p, and NCAPH expression. CRC cell migration and invasion were determined via Transwell assays. Western blot analysis was utilized to define the protein expression of epithelial-mesenchymal transition (EMT) markers and NCAPH. Xenograft tumor was established for exploration into the function of circEIF3I in CRC metastasis to the liver and lung. The binding between miR-328-3p and circEIF3I or NCAPH was predicted through ENCORI or TargetScan platform and ascertained through dual-luciferase reporter assays. circEIF3I and NCAPH expression were found to be elevated in CRC tissues and cells, while miR-328-3p was downregulated. Functionally, circEIF3I knockdown inhibited CRC cell migration, invasion, EMT, and tumor metastasis. Mechanistic analyses revealed that circEIF3I can target miR-328-3p, while NCAPH was targeted by miR-328-3p. Furthermore, circEIF3I facilitated NCAPH expression in CRC cells by sequestering miR-328-3p. Notably, miR-328-3p inhibitor or NCAPH overexpression negated the effects of circEIF3I knockdown on preventing CRC progression in vitro. Taken together, circEIF3I elevated NCAPH expression by sponging miR-328-3p, thereby promoting CRC metastasis. These findings suggest that the circEIF3I/miR-328-3p/NCAPH axis represents a novel therapeutic target for CRC.

hnRNPA2B1 drives colorectal cancer progression via the circCDYL/EIF4A3/PHF8 axis

The RNA-binding protein hnRNPA2B1 acts as an m6A reader and plays a role in tumor development. This study investigates the potential mechanism of hnRNPA2B1 in colorectal cancer (CRC) progression. The expression profiles of hnRNPA2B1, circCDYL, and PHF8 in CRC cell lines were analyzed. Following si-hnRNPA2B1 transfection, CRC cell proliferation, invasion, and migration were evaluated by CCK-8 and Transwell. CDYL expression was detected after actinomycin D and RNase R treatment. RIP was conducted to assess the enrichment of hnRNPA2B1 and m6A on circCDYL. RIP and RNA pull-down assays established the interaction between circCDYL and EIF4A3/PHF8. EIF4A3 expression was evaluated using RT-qPCR and Western blot techniques. hnRNPA2B1 and PHF8 displayed high expression levels, whereas circCDYL showed low expression levels in colorectal cancer cells. Inhibition of hnRNPA2B1 reduced CRC cell proliferation, migration, and invasion. hnRNPA2B1 mechanistically elevated the m6A level of circCDYL while decreasing its expression, which in turn reduced the binding of circCDYL to EIF4A3 and enhanced PHF8 expression. In summary, hnRNPA2B1-mediated m6A modification decreases circCDYL expression, which inhibits the interaction of circCDYL with EIF4A3, enhances PHF8 expression, and ultimately facilitates CRC progression.

Curcumin Inhibits the Development of Pancreatic Cancer by Targeting the circ_0079440/miR-522-3p/EIF4A1 Pathway

Pancreatic cancer (PC) is a common gastrointestinal cancer with high invasiveness and high mortality. Curcumin is a natural polyphenol with anti-tumor activity against different cancers, including PC. Curcumin has been verified to mediate the expression of circular RNAs (circRNAs) to inhibit tumor development. This study aimed to explore the function and regulatory mechanism of curcumin on circ_0079440 in PC. PC cells were treated with different concentrations of curcumin (0, 5, 10 or 15 μM) for 24 h. Gene expression in PC cells and tissues was detected using RT-qPCR. Cell malignant phenotypes were determined by functional assays. The levels of EMT-related proteins were tested using western blot. RNA interaction was determined using RNA pulldown assay, luciferase reporter assay and RIP assay. The results showed that curcumin suppressed cell proliferative, migratory, and invasive capabilities, and weakened epithelial-mesenchymal transition (EMT) in a concentration-dependent way. Circ_0079440 was expressed at a high level in PC and its level was reduced via curcumin administration in PC cells. Rescue assays showed that circ_0079440 overexpression reversed the suppressive effects of curcumin on PC cell malignant phenotypes. Furthermore, in the xenograft mouse models, curcumin treatment inhibited tumor growth and metastasis, and circ_0079440 upregulation reversed the function of curcumin. Additionally, circ_0079440 was revealed to bind to miR-522-3p to upregulate eukaryotic initiation factor 4A1 (EIF4A1) expression in PC cells. EIF4A1 expression was also downregulated by curcumin, and EIF4A1 overexpression abolished the suppressive functions of curcumin. Moreover, EIF4A overexpression or miR-522-3p inhibition counteracted the anti-tumor effects of circ_0079440 depletion on PC development. To sum up, curcumin suppresses PC development by targeting the circ_0079440/miR-522-3p/EIF4A1 pathway, which might provide novel therapeutic targets for treatment of PC.

CircAKT3 promotes prostate cancer proliferation and metastasis by enhancing the binding of RPS27A and RPL11

BACKGROUND

Metastatic prostate cancer (PCa) is a leading cause of mortality among PCa patients. Although circular RNAs (circRNAs) are recognized for their pivotal roles in tumorigenesis, the specifics of their influence within the context of PCa have yet to be fully elucidated.

METHODS

RT-qPCR was conducted to evaluate circAKT3 expression in PCa cells and in both tumor and adjacent noncancerous tissues. The oncogenic role of circAKT3 was confirmed through a combination of in vitro and in vivo experiments. Mechanistic investigations using RNA-pulldown, RNA immunoprecipitation (RIP), fluorescence in situ hybridization (FISH), immunofluorescence (IF), and Chromatin Immunoprecipitation (ChIP) assays explored how circAKT3 modulates c-Myc activity via interactions with RPS27A and RPL11. Additionally, Western Blotting and further in vitro and in vivo studies assessed circAKT3's influence on PCa progression through MST1.

RESULTS

This research identified the function and regulation of circAKT3, a circRNA derived from exons 2 to 8 of the kinase-b3 (AKT3) gene, in human PCa cells. CircAKT3 was significantly correlated with clinical indicators of disease severity, including D'Amico risk classification, the Gleason score, and pT stage. Both in vitro and in vivo experiments demonstrated that circAKT3 knockdown inhibited PCa cell proliferation, migration, and invasion. Lipid nanoparticles encapsulating si-circAKT3 (LNP-si-circAKT3) effectively suppressed the growth of bone tumors formed by PCa cells. Mechanistically, circAKT3 acted as a protein scaffold between ribosomal protein S27a (RPS27A) and ribosomal protein L11 (RPL11), promoting their cytoplasmic translocation and reducing nuclear RPL11 levels, ultimately diminishing RPL11's interaction with c-Myc and resulting in enhanced c-Myc-driven suppression of macrophage stimulating 1 (MST1) expression. Consequently, the decreased MST1 led to PCa progression and metastasis. CircAKT3 formation was facilitated by both flanking Alu elements and the RNA binding protein Quaking (QKI). Additionally, downregulation of the RNA helicase URH49 resulted in the nuclear accumulation of circAKT3, finally suppressing MST1 expression.

CONCLUSION

Our findings suggest that circAKT3 acts as a protein scaffold, promoting the interaction between RPS27A and RPL11, thereby influencing c-Myc activity and PCa progression. This study underscores the crucial role of circAKT3 in PCa and its potential as a therapeutic target to impede malignancy progression and metastasis.

circDENND4C serves as a sponge for miR-200b to drive non-small cell lung cancer advancement by regulating MMP-9 expression

Introduction

Lung cancer has a higher incidence and mortality rate than other cancers, especially non-small cell lung cancer (NSCLC), accounting for 85% of the cases. The role of the circDENND4C/miR-200b/matrix metalloproteinase-9 (MMP-9) regulatory axis in NSCLC remains largely unknown.

Methods

NSCLC cell lines were used to examine the expression of circDENND4C, miR-200b, and MMP-9 via qRT-PCR or Western blot. The target relationship of circDENND4C, miR-200b, and MMP-9 was examined by RNA fluorescence in situ hybridization (RNA-FISH), immunofluorescence (IF), dual-luciferase reporter system, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot. Then, a cell count kit-8 (CCK-8) experiment, flow cytometry, and migration/invasion assays were performed to assess the biological function of circDENND4C, miR-200b, and MMP-9 by transfecting with their overexpression or knockout plasmids in A549 cells. Finally, the proteins related to cell adhesion and tight junction were further tested by Western blot and IF.

Results

circDENND4C and MMP-9 were found to be highly expressed in NSCLC cell lines, while miR-200b was lowly expressed in NSCLC cell lines. Moreover, circDENND4C could sponge miR-200b to target MMP-9. Subsequently, it was observed that knockdown of circDENND4C and MMP-9 or the upregulation of miR-200b repressed cell proliferation and cell cycle progression, increased cell apoptosis, and hindered cell migration and invasion. Finally, it was also found that the circDENND4C/miR-200b/MMP-9 regulatory axis might be involved with cell adhesion and tight junction to influence tumor metastasis.

Conclusions

Altogether, our study reveals a novel regulatory loop in which the circDENND4C/miR-200b/MMP-9 axis may modulate NSCLC progression, indicating potential biomarkers for the diagnosis or treatment of NSCLC.

Leveraging epigenetic alterations in pancreatic ductal adenocarcinoma for clinical applications

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy characterized by late detection and poor prognosis. Recent research highlights the pivotal role of epigenetic alterations in driving PDAC development and progression. These changes, in conjunction with genetic mutations, contribute to the intricate molecular landscape of the disease. Specific modifications in DNA methylation, histone marks, and non-coding RNAs are emerging as robust predictors of disease progression and patient survival, offering the potential for more precise prognostic tools compared to conventional clinical staging. Moreover, the detection of epigenetic alterations in blood and other non-invasive samples holds promise for earlier diagnosis and improved management of PDAC. This review comprehensively summarises current epigenetic research in PDAC and identifies persisting challenges. These include the complex nature of epigenetic profiles, tumour heterogeneity, limited access to early-stage samples, and the need for highly sensitive liquid biopsy technologies. Addressing these challenges requires the standardisation of methodologies, integration of multi-omics data, and leveraging advanced computational tools such as machine learning and artificial intelligence. While resource-intensive, these efforts are essential for unravelling the functional consequences of epigenetic changes and translating this knowledge into clinical applications. By overcoming these hurdles, epigenetic research has the potential to revolutionise the management of PDAC and improve patient outcomes.

Circular RNA-Cacna1d Plays a Critical Role in Sepsis-induced Lung Injury by Sponging microRNA-185-5p

The role of circular RNAs (circRNAs) in sepsis-induced lung injury is not clear. This study investigated the role and molecular mechanism of a novel circRNA in sepsis-induced lung injury and explored its prognostic value in patients with sepsis. In this study, aberrant circRNA expression profiling in lung tissues from mice with sepsis-induced lung injury was analyzed using high-throughput sequencing. circRNA-Cacna1d was verified by qRT-PCR, and its biological function in sepsis-induced lung injury was validated in vitro and in vivo. The interactions among circRNA-Cacna1d, microRNAs (miRNAs), and their downstream genes were verified. Furthermore, the clinical value of circRNA-Cacna1d in peripheral blood from patients with sepsis was also evaluated. We found that circRNA-Cacna1d expression was significantly increased in lung tissues of mice with sepsis and in microvascular endothelial cells after LPS challenge. circRNA-Cacna1d knockdown alleviated inflammatory response and ameliorated the permeability of vascular endothelium, thereby mitigating sepsis-induced lung injury and significantly improving the survival rate of mice with sepsis. Mechanistically, circRNA-Cacna1d directly interacted with miRNA-185-5p and functioned as a miRNA sponge to regulate the RhoA/ROCK1 signaling pathway. The expression level of circRNA-Cacna1d in patients with early sepsis was significantly higher than that in the healthy control subjects. Higher levels of circRNA-Cacna1d in patients with sepsis were associated with increased disease severity and poorer outcomes. In conclusions, circRNA-Cacna1d may play a role in sepsis-induced lung injury by regulating the RhoA/ROCK1 axis by acting as a miRNA-185-5p sponge. circRNA-Cacna1d is a potential therapeutic target for sepsis-induced lung injury and a prognostic biomarker in sepsis.

Hsa_circ_0009910 knockdown in HeLa cells increases miR‑198 expression levels and decreases c‑Met expression levels and cell viability

Cervical cancer (CC) is considered a public health problem. Circular RNAs (circRNAs) serve important roles in different types of cancer, including CC. However, the mechanisms used by circRNAs to facilitate CC progression are currently unclear. The present study analyzed the effects of hsa_circ_0009910 knockdown on microRNA (miRNA/miR)-198 and mesenchymal-epithelial transition factor (c-Met) expression levels and its impact on apoptosis and the viability of HeLa cells. Differentially expressed circRNAs in CC were identified using analysis of circRNA microarray data. Bioinformatics analysis was performed to predict circRNA-microRNA (miRNA) and miRNA-mRNA interactions. The knockdown of hsa_circ_0009910 in HeLa cells was performed using small interfering RNA and the expression levels of hsa_circ_0009910, miR-198 and c-Met were assessed using reverse transcription-quantitative PCR. The viability and apoptosis of HeLa cells were evaluated using MTT, neutral red uptake and ApoLive-Glo™ multiplex assays. Hsa_circ_0009910 was significantly upregulated in HeLa cells and the knockdown of hsa_circ_0009910 increased miRNA-198 expression levels, reduced c-Met expression levels and decreased cellular viability, but not apoptosis, in HeLa cells. Overall, these results indicated that hsa_circ_0009910 could act as a molecular sponge of miRNA-198 and contribute to the upregulation of c-Met expression levels. The hsa_circ_0009910/miRNA-198/c-Met interaction network affects the viability, but not apoptosis, of HeLa cells. Based on this mechanism, the present study suggests that hsa_circ_0009910 may be a promising biomarker for CC.

CellCircLoc: Deep Neural Network for Predicting and Explaining Cell Line-Specific CircRNA Subcellular Localization

The subcellular localization of circular RNAs (circRNAs) is crucial for understanding their functional relevance and regulatory mechanisms. CircRNA subcellular localization exhibits variations across different cell lines, demonstrating the diversity and complexity of circRNA regulation within distinct cellular contexts. However, existing computational methods for predicting circRNA subcellular localization often ignore the importance of cell line specificity and instead train a general model on aggregated data from all cell lines. Considering the diversity and context-dependent behavior of circRNAs across different cell lines, it is imperative to develop cell line-specific models to accurately predict circRNA subcellular localization. In the study, we proposed CellCircLoc, a sequence-based deep learning model for circRNA subcellular localization prediction, which is trained for different cell lines. CellCircLoc utilizes a combination of convolutional neural networks, Transformer blocks, and bidirectional long short-term memory to capture both sequence local features and long-range dependencies within the sequences. In the Transformer blocks, CellCircLoc uses an attentive convolution mechanism to capture the importance of individual nucleotides. Extensive experiments demonstrate the effectiveness of CellCircLoc in accurately predicting circRNA subcellular localization across different cell lines, outperforming other computational models that do not consider cell line specificity. Moreover, the interpretability of CellCircLoc facilitates the discovery of important motifs associated with circRNA subcellular localization.

CircRNF13 enhances IGF2BP1 phase separation-mediated ITGB1 mRNA stabilization in an m6A-dependent manner to promote oral cancer cisplatin chemoresistance

Oral cancer ranks among the most common malignancies within the head and neck region; however, its etiology remains inadequately understood despite substantial research advances in recent years. Many studies highlight the regulatory role of circular RNAs (circRNAs) in human cancers, suggesting their potential as cancer biomarkers. However, their specific mechanisms in oral cancer are not well understood. This study analyzed circRNAs expression in oral cancer, identifying circRNF13 (circbaseID: has_circ_0006801) as having elevated expression in oral cancer cells and tissues. Our study demonstrated that circRNF13 is correlated with increased tumor grade and stage in oral cancer. Results from both in vitro and in vivo experiments indicated that circRNF13 enhances cancer cell proliferation and tumor growth, while concurrently diminishing tumor sensitivity to cisplatin. Mechanistically, circRNF13 interacts with the m6A "reader" protein IGF2BP1, inhibiting its ubiquitin-mediated degradation and promoting its phase separation formation. Subsequently, circRNF13 augments the stability of ITGB1 mRNA via IGF2BP1 in a manner dependent on m6A modification. The m6A modification of ITGB1 mRNA is modulated by the phase separation of IGF2BP1, thereby promoting the malignant progression of oral cancer cells. This evidence positions circRNF13 as a crucial regulatory molecule in the pathogenesis of oral cancer and suggests its potential as a therapeutic target. This discovery enriches our understanding of the mechanistic role of circRNAs.

GC-derived exosomal circMAN1A2 promotes cancer progression and suppresses T-cell antitumour immunity by inhibiting FBXW11-mediated SFPQ degradation

BACKGROUND

Exosomes, as extracellular membrane vesicles, play important roles in intercellular communication and can influence tumour progression. Circular RNAs (circRNAs) have been reported in various malignancies and are also important components of exosomes. However, the role of exosomal circRNAs in gastric cancer (GC) progression has not been completely clarified.

METHODS

The exosomal circRNAs enriched in GC were identified using exosomal circRNA sequencing. The biological function of circMAN1A2 in GC was investigated using a series of in vitro and in vivo experiments. PKH-67 staining was used to label the exosomes. The molecular mechanism of exosomal circMAN1A2 was investigated via mass spectrometry, immunoprecipitation, Western blot, and single-cell RNA-sequencing data analyses.

RESULTS

In our study, we determined that circMAN1A2 (hsa_circ_0000118) was enriched in GC-derived exosomes. Higher circMAN1A2 expression was related to poor survival in GC patients (HR = 2.917, p = 0.0120). Exosomal circMAN1A2 promoted GC progression in vitro and in vivo and suppressed the antitumour activity of T cells. Moreover, circMAN1A2 bound to SFPQ in GC cells and T cells, promoting the G1/S phase transition of the cell cycle in GC cells while inhibiting the activation of the T cell receptor signalling pathway in T cells to decrease antitumour activity. Mechanistically, circMAN1A2 competed with FBXW11 for binding to SFPQ, preventing FBXW11-mediated k48-linked ubiquitination and SFPQ protein degradation, thereby stabilizing SFPQ expression.

CONCLUSIONS

Our work confirms the critical role of exosomal circMAN1A2 in the progression and immunosuppression of GC. This novel axis of circMAN1A2-SFPQ provides new insights into exosomal circRNA-based GC diagnostic and therapeutic strategies.

Circular RNA ATP9A Stimulates Non-small Cell Lung Cancer Progression via MicroRNA-582-3p/Ribosomal Protein Large P0 Axis and Activating Phosphatidylinositol 3-Kinase/Protein Kinase B Signaling Pathway

Circular RNAs (circRNAs), along with their pathogenic property in non-small cell lung cancer (NSCLC), require comprehensive analyses and explanations. The study is established with the purpose to elucidate the potential molecular mechanism of circATP9A in NSCLC. CircATP9A and microRNA (miR)-582-3p were evaluated by real-time quantitative polymerase chain reaction, and ribosomal protein large P0 (RPLP0), cleaved caspase-3, cleaved Ki-67, epithelial-to-mesenchymal transition (EMT)-associated proteins (N-cadherin and E-cadherin), and core proteins of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway were by Western blot. The processes of proliferation, apoptosis, migration, and invasion were measured by cell counting kit-8, 5-ethynyl-2'deoxyuridine, flow cytometry, and Transwell. Gene interaction was verified by RNA immunoprecipitation and dual luciferase reporter assay. CircATP9A and RPLP0 were abnormally highly expressed in both NSCLC tissues and cell lines, while miR-582-3p was abnormally low. Knockdown of circATP9A reduced NSCLC proliferation, invasion migration, and EMT and promoted apoptosis. This was further validated in nude mouse xenograft experiments. The inhibitory effect of knockdown of circATP9A on NSCLC was reversed by knockdown of miR-582-3p. In addition, the promoting effect of overexpression of circATP9A on NSCLC was reversed by knockdown of RPLP0. Mechanistically, circATP9A acted as a competitive endogenous RNA, sequestering miR-582-3p away from its target, which in turn modulated the expression of RPLP0. CircATP9A activated the miR-582-3p/RPLP0 axis by regulating the PI3K/Akt pathway in NSCLC cells. CircATP9A stimulates NSCLC progression via miR-582-3p/RPLP0 axis and PI3K/AKT cascade activation.

Mechanisms and therapeutic implications of gene expression regulation by circRNA-protein interactions in cancer

Circular RNAs (circRNAs) have garnered substantial attention due to their distinctive circular structure and gene regulatory functions, establishing them as a significant class of functional non-coding RNAs in eukaryotes. Studies have demonstrated that circRNAs can interact with RNA-binding proteins (RBPs), which play crucial roles in tumorigenesis, metastasis, and drug response in cancer by influencing gene expression and altering the processes of tumor initiation and progression. This review aims to summarize the recent advances in research on circRNA-protein interactions (CPIs) and discuss the functions and mode of action of CPIs at various stages of gene expression, including transcription, splicing, translation, and post-translational modifications in the context of cancer. Additionally, we explore the role of CPIs in tumor drug resistance to gain a deeper understanding of their potential applications in the development of new anti-cancer therapeutic approaches.

Molecular Mechanisms of circKIF4A in Breast Cancer Progression

AIM

Breast cancer (BC) is the most frequently diagnosed malignancy worldwide, necessitating continued research into its molecular mechanisms. Circular RNAs (circRNAs) are increasingly recognized for their role in various cancers, including BC. This study explores the role of circRNA kinesin family member 4A (circKIF4A) in BC progression and its underlying molecular mechanisms.

METHODS

BC cell lines were cultured, and circKIF4A expression was knocked down. Cell viability, proliferation, migration, and invasion were assessed using the Cell Counting Kit-8, colony formation assay, and Transwell assays. The expression of circKIF4A, miR-874-3p, and glycerophosphodiester phosphodiesterase domain-containing 5 (GDPD5) was quantified using qRT-PCR and Western blot analysis. Subcellular fractionation was performed to localize circKIF4A within the cell. The interactions between circKIF4A and miR-874-3p, as well as between miR-874-3p and GDPD5, were evaluated using RNA pull-down and dual-luciferase assays. Rescue experiments were conducted with miR-874-3p inhibition or GDPD5 overexpression to confirm the mechanistic pathway.

RESULTS

circKIF4A was found to be upregulated in BC cells. Its knockdown significantly inhibited cell proliferation, migration, and invasion. circKIF4A acts as a sponge for miR-874-3p, reducing its expression. miR-874-3p targets and suppresses GDPD5, a key regulator in BC cell growth. Silencing miR-874-3p or overexpressing GDPD5 reversed the tumor-suppressive effects of circKIF4A knockdown.

CONCLUSION

circKIF4A promotes BC cell proliferation and invasiveness by regulating the miR-874-3p/GDPD5 axis. These findings highlight a potential therapeutic target in BC and contribute to the understanding of circRNA involvement in cancer progression.

Circular RNAs: key players in tumor immune evasion

Immune responses against tumor antigens play a role in confining tumor growth. In response, cancer cells developed several mechanisms to bypass or defeat these anti-tumor immune responses-collectively referred to as "tumor immune evasion". Recent studies have shown that a group of non-coding RNAs, namely circRNAs affect several aspects of tumor immune evasion through regulation of activity of CD8 + T cells, regulatory T cells, natural killer cells, cytokine-induced killer cells or other immune cells. Understanding the role of circRNAs in this process facilitate design of novel therapies for enhancing the anti-tumor capacity of immune system. This review provides an outline of different roles of circRNAs in the tumor immune evasion.

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

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

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

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

Revealing the Complex Interaction of Noncoding RNAs, Sirtuin Family, and Mitochondrial Function

Mitochondria are key organelles that perform and coordinate various metabolic processes in the cell, and their homeostasis is essential for the maintenance of eukaryotic life. To maintain mitochondrial homeostasis and cellular health, close communication between noncoding RNAs (ncRNAs) and proteins is required. For example, there are numerous crosstalk between ncRNAs and the sirtuin (SIRT1-7) family, which is a group of nicotinamide adenine dinucleotides (NAD(+))-dependent Type III deacetylases. NcRNAs are involved in the regulation of gene expression of sirtuin family members, and deacetylation of sirtuin family members can also influence the generation of ncRNAs. This review focuses on the relationship between the two mentioned above and summarizes the impact of their interactions on mitochondrial metabolism, oxidative stress, mitochondrial apoptotic pathways, mitochondrial biogenesis, mitochondrial dynamics, and other mitochondria-related pathophysiological processes. Finally, the review also describes targeted and appropriate treatment strategies. In conclusion, we provide an overview of the ncRNA-sirtuins/mitochondria relationship that could provide a reference for related research in the mitochondrial field and help the future development of new biomedical applications in this area.

In Rheumatoid Arthritis, A Review of ncRNAs Related to NF-κB Signaling Pathways

Rheumatoid arthritis (RA) is an autoimmune disease with no known cure that results in joint deformities and dysfunction, significantly impacting the quality of life of patients. The abnormal NF-κB signaling pathway in RA has emerged as a crucial research area for the development of RA therapies, with non-coding RNAs (ncRNAs) serving as a potentially meaningful avenue to regulate it. Thus, understanding the role of ncRNAs in RA and the identification of new therapeutic targets have become pressing issues in the field. In this review, we aim to summarize recent studies on ncRNAs that regulate the NF-κB signaling pathway in RA, including miRNAs, lncRNAs, and circRNAs, as well as the mechanisms by which drugs modulate NF-κB activity. By highlighting these recent advances, we hope to promote further research into targeted RA therapy and provide novel directions and ideas for researchers in the field.

Circ_0006174 Upregulates IGF1R to Enhance Radioresistance and Tumorigenesis in Colorectal Cancer via miR-940 Suppression

Colorectal cancer (CRC) is one of the most common malignancies all over the world. Increasing evidence has revealed that circular RNAs (circRNAs) are involved in the progression of CRC. In this study, we aimed to investigate the role and underlying mechanism of circ_0006174 in the development and radiosensitivity of CRC. Circ_0006174, microRNA-940 (miR-940), and insulin-like growth factor 1 receptor (IGF1R) expression levels were evaluated by real-time quantitative polymerase chain reaction (RT-qPCR). The radiosensitivity of cells also was assessed using colony formation assay. Besides, cell proliferation, apoptosis, migration, and invasion were detected by cell counting kit-8 (CCK-8), flow cytometry, and transwell assays. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were performed to verify the relationship between miR-940 and circ_0006174 or IGF1R. IGF1R protein level was examined using western blot. A xenograft tumor model was used to verify the function of circ_0006174 in CRC tumor growth in vivo. Circ_0006174 and IGF1R levels were elevated and miR-940 expression was decreased in CRC tissues and cells. Circ_0006174 knockdown enhanced the radiosensitivity of CRC cells by regulating cell proliferation, apoptosis, migration, and invasion in vitro. In mechanism, circ_0006174 served as a sponge for miR-940 to upregulate IGF1R expression. Moreover, circ_0006174 silencing suppressed CRC growth in vivo. Circ_0006174 boosts radioresistance of CRC cells at least partly through upregulating IGF1R expression by sponging miR-940, providing a novel theoretical basis for CRC therapy.

Exosomes containing circSCP2 in colorectal cancer promote metastasis via sponging miR-92a-1-5p and interacting with PTBP1 to stabilize IGF2BP1

Exosomes have emerged as significant biomarkers for multiple diseases, including cancers. Circular RNAs (circRNAs), abundant in exosomes, are involved in regulating cancer development. However, the regulatory function and the underlying molecular mechanism of hsa_circ_0006906 (circSCP2) in colorectal cancer (CRC) metastasis remain unclear. A competing endogenous RNA microarray was used to analyze circRNA expression in serum exosomes in patients with CRC at early and late stages. circSCP2 expression was evaluated using qRT-PCR. The biological functions of circSCP2 in CRC were assessed through in vitro and in vivo experiments. The molecular mechanism of circSCP2 was explored using western blotting, RNA pulldown, RNA immunoprecipitation, luciferase assays, and relative rescue experiments. circSCP2 expression was significantly elevated in CRC tissues, with higher levels in serum exosomes correlating with advanced TNM stages. circSCP2 knockdown inhibited CRC cell proliferation, migration, invasion, and metastasis in vitro and in vivo. Mechanistically, circSCP2 sponged miR-92a-1-5p to increase insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) expression. Additionally, circSCP2 directly bound to and stabilized polypyrimidine tract binding protein 1 (PTBP1) by inhibiting protein ubiquitination, resulting in IGF2BP1 mRNA stabilization and enhanced CRC migration and invasion. Our findings demonstrate that circSCP2 regulates the miR-92a-1-5p/IGF2BP1 pathway, promotes PTBP1/IGF2BP1 interaction, and accelerates CRC progression. Exosomal circSCP2 is a promising circulating biomarker for CRC prognosis and needs further therapeutic investigation.

A Novel Approach for Bladder Cancer Treatment: Nanoparticles as a Drug Delivery System

Bladder cancer represents one of the most prevalent malignant neoplasms of the urinary tract. In the Asian context, it represents the eighth most common cancer in males. In 2022, there were approximately 613,791 individuals diagnosed with bladder cancer worldwide. Despite the availability of efficacious treatments for the two principal forms of bladder cancer, namely non-invasive and invasive bladder cancer, the high incidence of recurrence following treatment and the suboptimal outcomes observed in patients with high-grade and advanced disease represent significant concerns in the management of bladder cancer at this juncture. Nanoparticles have gained attention for their excellent properties, including stable physical properties, a porous structure that can be loaded with a variety of substances, and so on. The in-depth research on nanoparticles has led to their emergence as a new class of nanoparticles for combination therapy, due to their advantageous properties. These include the extension of the drug release window, the enhancement of drug bioavailability, the improvement of drug targeting ability, the reduction of local and systemic toxicity, and the simultaneous delivery of multiple drugs for combination therapy. As a result, nanoparticles have become a novel agent of the drug delivery system. The advent of nanoparticles has provided a new impetus for the development of non-surgical treatments for bladder cancer, including chemotherapy, immunotherapy, gene therapy and phototherapy. The unique properties of nanoparticles have facilitated the combination of diverse non-surgical therapeutic modalities, enhancing their overall efficacy. This review examines the recent advancements in the use of nanoparticles in non-surgical bladder cancer treatments, encompassing aspects such as delivery, therapeutic efficacy, and the associated toxicity of nanoparticles, as well as the challenges encountered in clinical applications.

Circular RNA LMBR1 inhibits bladder cancer progression by enhancing expression of the protein ALDH1A3

Background

Circular RNAs (circRNAs) have been identified as playing an integral role in the development of bladder cancer (BC). However, the mechanism by which circRNAs operate in the chemical carcinogenesis of BC remains unclear.

Methods

To explore this mechanism, we used RNA high-throughput sequencing to identify differentially expressed circRNA in bladder epithelial cells and chemically induced malignant transformed BC cells. Subsequently, in vitro experiments were conducted to investigate the biological function and molecular mechanism of circLMBR1 in BC. Finally, animal experiments were conducted to examine the clinical relevance of circLMBR1 in vivo.

Results

Our profiling of circular RNA expression during cellular malignant transformation induced by chemical carcinogens identified a subset of circRNAs associated with cell transformation. We verified that the expression of circLMBR1 in bladder epithelial malignant transformed cells was decreased compared with control cells, as well as in BC tissues and bladder cell lines. Furthermore, circLMBR1 was seen to inhibit the proliferation, invasion, and migration of BC cells both in vitro and in vivo. Mechanistically, circLMBR1 was found to exert its antitumor effect by binding to the protein ALDH1A3.

Conclusions

Our findings have revealed that circLMBR1 inhibits the progression of BC cells by binding to ALDH1A3 and upregulating its expression. As such, circLMBR1 serves as a promising predictor of BC and may provide a novel therapeutic target for the treatment of BC.

The emerging role of circular RNAs in cisplatin resistance in ovarian cancer: From molecular mechanism to future potential

Ovarian cancer (OC) is the most common cause of death in female cancers. The prognosis of OC is very poor due to delayed diagnosis and identification of most patients in advanced stages, metastasis, recurrence, and resistance to chemotherapy. As chemotherapy with platinum-based drugs such as cisplatin (DDP) is the main treatment in most OC cases, resistance to DDP is an important obstacle to achieving satisfactory therapeutic efficacy. Consequently, knowing the different molecular mechanisms involved in resistance to DDP is necessary to achieve new therapeutic approaches. According to numerous recent studies, non-coding RNAs (ncRNAs) could regulate proliferation, differentiation, apoptosis, and chemoresistance in many cancers, including OC. Most of these ncRNAs are released by tumor cells into human fluid, allowing them to be used as tools for diagnosis. CircRNAs are ncRNA family members that have a role in the initiation, progression, and chemoresistance regulation of various cancers. In the current study, we investigated the roles of several circRNAs and their signaling pathways on OC progression and also on DDP resistance during chemotherapy.

The implications for urological malignancies of non-coding RNAs in the the tumor microenvironment

Urological malignancies are a major global health issue because of their complexity and the wide range of ways they affect patients. There's a growing need for in-depth research into these cancers, especially at the molecular level. Recent studies have highlighted the importance of non-coding RNAs (ncRNAs) – these don't code for proteins but are crucial in controlling genes – and the tumor microenvironment (TME), which is no longer seen as just a background factor but as an active player in cancer progression. Understanding how ncRNAs and the TME interact is key for finding new ways to diagnose and predict outcomes in urological cancers, and for developing new treatments. This article reviews the basic features of ncRNAs and goes into detail about their various roles in the TME, focusing specifically on how different ncRNAs function and act in urological malignancies.

Peptidylprolyl isomerase D circular RNA sensitizes breast cancer to trastuzumab through remodeling HER2 N4-acetylcytidine modification

Human epidermal growth factor receptor 2 (HER2) overexpression and activation are crucial for trastuzumab resistance in HER2-positive breast cancer; however, the potential regulatory mechanism of HER2 is still largely undetermined. In this study, a novel circular RNA derived from peptidylprolyl isomerase D (PPID) is identified as a negative regulator of trastuzumab resistance. Circ-PPID is highly stable and significantly downregulated in trastuzumab-resistant cells and tissues. Restoration of circ-PPID markedly enhances HER2-positive breast cell sensitivity to trastuzumab in vitro and in vivo. Circ-PPID directly binds to N-acetyltransferase 10 (NAT10) in the nucleus and blocks the interaction between NAT10 and HER2 mRNA, reducing N4-acetylcytidine (ac4C) modification on HER2 exon 25, leading to HER2 mRNA decay. Intriguingly, the subcellular localization of circ-PPID differs between trastuzumab-sensitive and -resistant cells. Circ-PPID in trastuzumab-resistant cells is located more in the cytoplasm, mainly due to the upregulation of Exportin 4 (XPO4), which results in the loss of spatial conditions for circ-PPID to bind to nuclear NAT10. Taken together, our data suggest that circ-PPID is a previously unappreciated ac4C-dependent HER2 epigenetic regulator, providing a promising therapeutic direction for overcoming trastuzumab resistance in clinical setting.

CircJPH1 regulates the NF-κB/HERC5 axis to promote the malignant progression of esophageal squamous cell carcinoma through binding to XRCC6

Esophageal squamous cell carcinoma (ESCC) is a prevalent and malignant cancer with an unknown pathogenesis and a poor prognosis; therefore, the identification of effective biomarkers and targets is crucial for its diagnosis and treatment. Circular (circ)RNAs are prominent functional biomarkers and therapeutic targets in various diseases, particularly cancer, due to their widespread expression and regulatory mechanisms. Our study aimed to investigate the therapeutic potential of circRNA for ESCC. We identified Hsa_circ_0137111 for the first time as one of the most significantly up-regulated genes in ESCC sequencing and named it circJPH1. The results of the present study demonstrated an enhanced expression of circJPH1 in ESCC tissues. Moreover, circJPH1-knockdown could significantly inhibit the proliferation, migration, and invasion of ESCC cells, while its overexpression promoted these characteristics. In addition, circJPH1 promoted ESCC cell tumor growth in vivo. For the first time, mass spectrometry and RNA pull-down analysis revealed the interaction of X-ray repair cross-complementary 6 (XRCC6) protein with circJPH1, thereby promoting its nuclear translocation. Consequently, the nuclear factor kappa-B (NF-κB) signaling pathway was activated, leading to an up-regulation of HECT and RLD domain containing E3 ubiquitin protein ligase 5 (HERC5), thereby promoting ESCC progression. In summary, the present study elucidated the regulatory impact of circJPH1 on ESCC progression in vitro and in vivo, thereby indicating its potential role in ESCC treatment.

Circ_0011058 alleviates RA pathology through the circ_0011058/miR-335-5p/CUL4B signal axis

Our previous study found that Cullin 4B (CUL4B) inhibited rheumatoid arthritis (RA) pathology through glycogen synthase kinase-3beta (GSK3β)/canonical Wnt signalling pathway. In this work, pre-experiment and bioinformatics analysis suggested that circ_0011058 may lead to the up-regulation of CUL4B expression by inhibiting miR-335-5p. Therefore, we studied whether circ_0011058 can promote the expression of CUL4B through sponging the miR-335-5p and further promote the pathological development of RA. Bioinformatics prediction, real-time quantitative PCR (RT-qPCR), western blot (WB), double luciferase reporter gene and other relevant methods were used to study the inhibition of circ_0011058 on RA pathology and its molecular mechanism. Results showed that the expression of circ_0011058 was significantly increased in adjuvant arthritis (AA) rats and RA fibroblast-like synoviocytes (FLS). The knockout of circ_0011058 inhibited the proliferation of AA FLS and RA FLS, decreased the levels of interleukin-1 beta (IL-1β), interleukin 6 (IL-6), interleukin 8 (IL-8), and inhibited the expression of matrix metalloproteinase 3 (MMP3), fibronectin, which showed that circ_0011058 had a strong role in promoting RA pathology. Furthermore, miR-335-5p expression was reduced in AA rats and RA FLS. The highly expressed circ_0011058 directly sponged the miR-335-5p, which led to the increase of CUL4B expression and promoted the activation of the GSK3β/canonical signalling pathway. Finally, we confirmed that miR-335-5p mediated the roles of circ_0011058 in promoting RA pathological development, which showed that the circ_0011058/miR-335-5p/CUL4B signal axis was involved in RA pathology. This work was of great significance for clarifying the roles of circ_0011058 in RA pathology, and further work was needed to establish whether circ_0011058 was a potential therapeutic target or diagnostic marker for RA.

Noncoding RNAs in chronic obstructive pulmonary disease: From pathogenesis to therapeutic targets

Chronic obstructive pulmonary disease (COPD) is the most prevalent chronic respiratory disorder that is becoming the leading cause of morbidity and mortality on a global scale. There is an unmet need to investigate the underlying pathophysiological mechanisms and unlock novel therapeutic avenues for COPD. Recent research has shed light on the significant roles played by diverse noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), in orchestrating the development and progression of COPD. This review provides an overview of the regulatory roles of ncRNAs in COPD, elucidating their underlying mechanisms, and illuminating the potential prospects of RNA-based therapeutics in the management of COPD.

Circ-RNF111 Promotes Proliferation of Ovarian Cancer Cell SKOV-3 by Targeting the MiR-556-5p/CCND1 Axis

The aim of this study was to investigate the role and mechanism of circ-RNF111 in the human ovarian cancer cell line SKOV-3. First, qRT-PCR was used to detect circ-RNF111 and miR-556-5p expression levels in human normal ovarian epithelial cells IOSE80 and human ovarian cancer cells SKOV-3. CCK-8 and colony formation assays were adopted to determine the proliferation rate and cell viability of SKOV-3 cells, respectively. Additionally, in an attempt to reveal the mechanism of circ-RNF111, we predicted the targeting relationship between miR-556-5p and circ-RNF111 as well as miR-556-5p and CCND1 using the circinteractome and TargetScan databases, respectively, and validated their relationship by dual-luciferase reporter assay. The protein expression levels of CCND1 in SKOV-3 cells were detected by Western blot. Based on the above experiments, the expression of circ-RNF111 was found to be up-regulated in SKOV-3, and the knockdown of circ-RNF111 significantly inhibited the proliferation and viability of SKOV-3 cells. Then we confirmed that circ-RNF111 sponged miR-556-5p in SKOV-3 cells to up-regulate CCND1 expression. In addition, simultaneous inhibition of miR-556-5p or overexpression of CCND1 in SKOV-3 cells with knockdown of circ-RNF111 reversed the inhibitory effect of knockdown of circ-RNF111 on the protein expression level of CCND1, cell proliferation rate, and cell viability. In summary, circ-RNF111 promotes the proliferation of SKOV-3 cells by targeting the miR-556-5p/CCND1 axis. Circ-RNF111 may serve as a potential target for ovarian cancer therapy.

The role of circRNAs in resistance to doxorubicin

Doxorubicin is an anthracyline recognized as an antitumor antibiotic agent. It is widely used in the chemotherapeutic regimens in different types of cancers. Resistance to doxorubicin is a major clinical obstacle and main cause of failure in cancer chemotherapy. Among different mechanisms involved in this process, the role of epigenetic factors has been highlighted. Circular RNAs (circRNAs) have a prominent role in this process. Here, we summarize the recent findings on the role of circRNAs in doxorubicin resistance, particularly in breast cancer and osteosarcoma and underscore their clinical application as potential biomarkers and therapeutic targets in this field. Recognition of the underlying mechanism of circRNAs involvement in doxorubicin resistance will expand our understanding of chemoresistance establishment and may provide a prospect to develop circRNA-based predictive biomarkers of chemotherapy or therapeutic strategies for cancer patients.

CircKRT75 augments the cisplatin chemoresistance of nasopharyngeal carcinoma via targeting miR-659/CCAR2 axis

Cisplatin resistance is a clinical challenge limiting the treatment of nasopharyngeal carcinoma (NPC). CircRNAs have been evidenced as key molecules involved in tumor advancement and drug resistance. The present study aimed to elucidate the potential biological value of circKRT75 in NPC cisplatin resistance. CircKRT75 levels in NPC clinical samples and parental/resistant cell lines were analyzed based on qRT-PCR. CCK-8 and flow cytometry were adopted to assess the impacts of circKRT75 on the growth viability and apoptotic ability of NPC resistant cells. Meanwhile, western blot was performed to detect changes in the expression of apoptosis-related proteins. Bioinformatics analysis predicted miRNAs and mRNAs downstream of circKRT75, and the interaction between circKRT75 and downstream targets was validated by RNA pull-down, dual-luciferase reporter and rescue experiments. CircKRT75 was notably enhanced in NPC tissues and NPC cisplatin-resistant cells. Functional experiments disclosed that circKRT75 silencing repressed NPC-resistant cell growth and promoted apoptosis. Bioinformatics screening identified that circKRT75 performed as a molecular sponge for miR-659, and CCAR2 was a direct target of miR-659. Further rescue assays confirmed that miR-659 inhibitor restored the inhibitory effect of circKRT75 knockdown on the growth of drug-resistant cells, while CCAR2 silencing could reverse the promotion of NPC cisplatin resistance by circKRT75 upregulation. Additionally, animal experiments revealed that circKRT75 knockdown restrained NPC cisplatin resistance in vivo. CircKRT75 contributed to cisplatin resistance in NPC through miR-659/CCAR2 signaling, which provided a novel perspective and direction to solve the problem of chemoresistance in NPC.

circUBE2G1 interacts with hnRNPU to promote VEGF-C-mediated lymph node metastasis of lung adenocarcinoma

Background

Patients with lymph node(LN)metastasis-positive Lung adenocarcinoma(LUAD)suffer from a significantly reduced five-year survival rate. Increasing evidence indicates circular RNAs(circRNAs)play crucial roles in regulating cancer progression. However, the specific regulatory mechanisms of circRNAs in the LN metastasis of LUAD have not been fully explored.

Methods

GEO datasets and sequence analysis were applied for the identification of differentially expressed circRNAs between LUAD tissues and adjacent normal tissues. In vitro and in vivo experiments were performed to evaluate the function of circUBE2G1. The interaction between circUBE2G1 and VEGF-C was determined by RNA pulldown, ChIP, ChIRP and luciferase assays.

Results

In this study, we identified a novel circRNA, circUBE2G1 (hsa_circ_0041555), which is upregulated in LUAD and positively correlated with LN metastasis in patients with LUAD. Functionally, overexpression of circUBE2G1 promotes lymphangiogenesis and LN metastasis of LUAD both in vitro and in vivo. Mechanistically, circUBE2G1 activates the transcription of vascular endothelial growth factor C (VEGF-C) by recruiting hnRNPU to enhance H3K27ac on the VEGF-C promoter, thereby facilitating lymphangiogenesis and LN metastasis in LUAD.

Conclusion

Our findings offer new insights into the mechanisms behind circRNA-mediated LN metastasis in LUAD and suggest that circUBE2G1 may serve as a potential therapeutic target for LN metastasis in LUAD.

The functional roles of competitive endogenous RNA (ceRNA) networks in apoptosis in human cancers: The circRNA/miRNA/mRNA regulatory axis and cell signaling pathways

Circular RNAs are noncoding RNAs with circular conformation mainly due to backsplicing event. CircRNAs can potentially impact cell biological processes by interacting with cell signaling pathways. Numerous circRNAs have been found to be aberrantly expressed in a variety of cancers. These RNAs can act as ceRNA (competitive endogenous RNA) by sponging certain miRNAs to form circRNA/miRNA/mRNA networks. Dysregulation of ceRNA networks may lead to dysfunctions in various cell pathways, which modulate apoptosis-associated genes and ultimately result in cancer progression. Since disruption of apoptosis is one of the leading causes of cancer development, one approach for cancer treatment is to drive cells toward apoptosis. In this review, we present a summary of studies on the role of ceRNA networks in cellular signaling pathways that regulate apoptosis; these networks are suggested to be potential biomarkers for cancer treatment.

Downregulation of circSTX6 suppresses tumor progression while facilitating radiosensitivity in cervical squamous cell carcinoma

Background

cervical squamous cell carcinoma (CSCC) is the second gynecological tumors that seriously threaten women's life quality. Circular RNA (circRNA) is related with cervical cancer carcinogenesis and radiosensitivity.

Aim

To investigate the performance of hsa_circ_0007905 (circSTX6) on regulating cellular activities and radiosensitivity in CSCC.

Methods

The relative expression of circSTX6 in different tissue samples was detected by RT-qPCR. The cellular activity influence of circSTX6 in cervical cancer cells was measured by CCK-8 and Transwell assays. The survival fractions of cancer cells were detected after the radiation treatment to explore the relationship between circSTX6 and radiosensitivity of cervical cancer. The downstream miRNAs were predicted and analyzed. Rescue experiments confirmed their targeting relationship. Bioinformatic analysis was performed to identify the potential targets of miR-203a-3p.

Results

circSTX6 was increased and miR-203a-3p was decreased in cervical cancer tissues and radio-resistant tissues. CircSTX6 expression was related to the patient's survival rates. CircSTX6 absence decreased cervical cancer cell proliferation and invasion while enhancing the sensitivity of cervical cancer cells to radiotherapy by regulating miR-203a-3p. RAB27B may be a target of miR-203a-3p.

Conclusion

circSTX6 may be a clinical prognostic biomarker in CSCC. The absence of circSTX6 inhibits cellular behaviors and increases the sensitivity of cervical cancer cells to radiation by modulating miR-203a-3p/RAB27B axis.