Hsa_circ_0046263 functions as a ceRNA to promote nasopharyngeal carcinoma progression by upregulating IGFBP3

CircVIRMA enhances cell malignant behavior by governing the miR-452-5p/CREBRF pathway in cervical cancer

Our current study aimed to investigate the role and mechanism of circVIRMA in cervical cancer (CC) progression. CircVIRMA, microRNA-452-5p (miR-452-5p) and CREB3 regulatory factor (CREBRF) mRNA levels were examined in CC via quantitative real-time PCR (qRT-PCR). The protein level of CREBRF in CC was checked by Western blot. Cell Counting Kit-8 (CCK-8), colony formation, 5-Ethynyl-2'-deoxyuridine (EdU) staining, cell cycle, flow cytometry and transwell assays were conducted to estimate the effects of circVIRMA on malignant phenotypes of CC tumors. Western blot was used to measure related marker protein levels. The interaction between miR-452-5p and circVIRMA or CREBRF was predicted by bioinformatics analysis and verified by dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. Xenograft assay was used to assess the effect of circVIRMA on tumor growth in vivo. Immunohistochemistry (IHC) assay was performed to detect Ki-67 expression in tissues of mice. CircVIRMA and CREBRF levels were upregulated, while miR-452-5p was downregulated in CC tissues and cells. CircVIRMA silencing restrained CC cell proliferation, migration and invasion whereas induced apoptosis in vitro. In addition circVIRMA knockdown markedly attenuated xenograft tumor growth in vivo. circVIRMA was an efficient molecular sponge for miR-452-5p, and negatively regulated miR-452-5p expression. circVIRMA regulated CREBRF expression to modulate CC progression via miR-452-5p. MiR-452-5p downregulation reversed the effects of circVIRMA knockdown on CC progression. MiR-452-5p directly targeted CREBRF, and CREBRF overexpression partly restored the impact of miR-452-5p mimics on CC progression. circVIRMA mediated CC progression via regulating miR-452-5p/CREBRF axis, providing a novel therapeutic target for CC treatment.

Emerging roles of circular RNAs in nasopharyngeal carcinoma: functions and implications

Nasopharyngeal carcinoma (NPC) is a distinct malignancy primarily prevalent in Southern China and Southeast Asia. Circular RNAs (circRNAs), a class of non-coding RNAs, are evolutionarily conserved and exhibit remarkable stability. Their dysregulation has been observed in various cancers, including NPC. In this review, we investigate the pivotal role of circRNAs in NPC, focusing specifically on their involvement in tumor proliferation, apoptosis, metastasis, angiogenesis, stemness, metabolism, and the tumor microenvironment. We highlight the diagnostic and prognostic potential of circRNAs in NPC, emphasizing their utility as biomarkers for early detection, disease monitoring, and prediction of treatment outcomes. Additionally, we explore the therapeutic implications of circRNAs in NPC, highlighting their potential for targeted therapies.

Circular RNA COL1A1 promotes Warburg effect and tumor growth in nasopharyngeal carcinoma

OBJECTIVE

Circular RNAs (circRNAs), pivotal in the pathogenesis and progression of nasopharyngeal carcinoma (NPC), remain a significant point of investigation for potential therapeutic interventions. Our research was driven by the objective to decipher the roles and underlying mechanisms of hsa_circ_0044569 (circCOL1A1) in governing the malignant phenotypes and the Warburg effect in NPC.

METHODS

We systematically collected samples from NPC tissues and normal nasopharyngeal epithelial counterparts. The expression levels of circCOL1A1, microRNA-370-5p (miR-370-5p), and prothymosin alpha (PTMA) were quantitatively determined using quantitative polymerase chain reaction (qPCR) and Western blotting. Transfections in NPC cell lines were conducted using small interfering RNAs (siRNAs) or vectors carrying the pcDNA 3.1 construct for overexpression studies. We interrogated the circCOL1A1/miR-370-5p/PTMA axis's role in cellular functions through a series of assays: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide for cell viability, colony formation for growth, Transwell assays for migration and invasion, and Western blotting for protein expression profiling. To elucidate the molecular interactions, we employed luciferase reporter assays and RNA immunoprecipitation techniques.

RESULTS

Our investigations revealed that circCOL1A1 was a stable circRNA, highly expressed in both NPC tissues and derived cell lines. A correlation analysis with clinical pathological features demonstrated a significant association between circCOL1A1 expression, lymph node metastasis, and the tumor node metastasis staging system of NPC. Functionally, silencing circCOL1A1 led to substantial suppression of cell proliferation, migration, invasion, and metabolic alterations characteristic of the Warburg effect in NPC cells. At the molecular level, circCOL1A1 appeared to modulate PTMA expression by acting as a competitive endogenous RNA or 'sponge' for miR-370-5p, which in turn promoted the malignant characteristics of NPC cells.

CONCLUSION

To conclude, our findings delineate that circCOL1A1 exerts its oncogenic influence in NPC through the modulation of the miR-370-5p/PTMA signaling axis.

Uncovering the ceRNA network and DNA methylation associated with gene expression in nasopharyngeal carcinoma

OBJECTIVE

This study aimed to uncover abnormally expressed genes regulated by competitive endogenous RNA (ceRNA) and DNA methylation nasopharyngeal carcinoma and to validate the role of lncRNAs in the ceRNA network on nasopharyngeal carcinoma progression.

METHODS

Based on the GSE64634 (mRNA), GSE32960 (miRNA), GSE95166 (lncRNA), and GSE126683 (lncRNA) datasets, we screened differentially expressed mRNAs, miRNAs and lncRNAs in nasopharyngeal carcinoma. A ceRNA network was subsequently constructed. Differentially methylated genes were screened using the GSE62336 dataset. The abnormally expressed genes regulated by both the ceRNA network and DNA methylation were identified. In the ceRNA network, the expression of RP11-545G3.1 lncRNA was validated in nasopharyngeal carcinoma tissues and cells by RT-qPCR. After a knockdown of RP11-545G3.1, the viability, migration, and invasion of CNE-2 and NP69 cells was assessed by CCK-8, wound healing and Transwell assays.

RESULTS

This study identified abnormally expressed mRNAs, miRNAs and lncRNAs in nasopharyngeal carcinoma tissues. A ceRNA network was constructed, which contained three lncRNAs, 15 miRNAs and 129 mRNAs. Among the nodes in the PPI network based on the mRNAs in the ceRNA network, HMGA1 was assessed in relation to the overall and disease-free survival of nasopharyngeal carcinoma. We screened two up-regulated genes regulated by the ceRNA network and hypomethylation and 26 down-regulated genes regulated by the ceRNA network and hypermethylation. RP11-545G3.1 was highly expressed in the nasopharyngeal carcinoma tissues and cells. Moreover, the knockdown of RP11-545G3.1 reduced the viability, migration, and invasion of CNE-2 and NP69 cells.

CONCLUSION

Our findings uncovered the epigenetic regulation in nasopharyngeal carcinoma and identified the implications of RP11-545G3.1 on the progression of nasopharyngeal carcinoma.

RNA-Based Liquid Biopsy in Head and Neck Cancer

Head and neck cancer (HNC) is a prevalent and diverse group of malignancies with substantial morbidity and mortality rates. Early detection and monitoring of HNC are crucial for improving patient outcomes. Liquid biopsy, a non-invasive diagnostic approach, has emerged as a promising tool for cancer detection and monitoring. In this article, we review the application of RNA-based liquid biopsy in HNC. Various types of RNA, including messenger RNA (mRNA), microRNA (miRNA), long non-coding RNA (lncRNA), small nuclear RNA (snRNA), small nucleolar RNA (snoRNA), circular RNA (circRNA) and PIWI-interacting RNA (piRNA), are explored as potential biomarkers in HNC liquid-based diagnostics. The roles of RNAs in HNC diagnosis, metastasis, tumor resistance to radio and chemotherapy, and overall prognosis are discussed. RNA-based liquid biopsy holds great promise for the early detection, prognosis, and personalized treatment of HNC. Further research and validation are necessary to translate these findings into clinical practice and improve patient outcomes.

IGFBP3 epigenetic promotion induced by METTL3 boosts cardiac fibroblast activation and fibrosis

Cardiac fibrosis remains an unresolved problem in heart disease. Its etiology is directly caused by the activation and proliferation of cardiac fibroblasts (CFs). However, there is limited information regarding the biological role of cardiac fibroblasts in cardiac fibrosis. Herein, we screened out a gene, IGFBP3, whose expression significantly increased in TGF-β1-stimulated human primary CFs by mining RNA-Seq data for differential and WGCNA. We verified the IGFBP3's expression in transverse aortic constriction (TAC) surgery, isoproterenol (ISO)-induced cardiac fibrosis models, and TGFβ1-stimulated mouse primary CFs. We also found that the knockdown of IGFBP3 could inhibit the migration and proliferation ability of CFs. Furthermore, we found that aberrant N6-methyladenosine(m6A) mRNA modifications in the animal model and activated CFs may regulate the expression of IGFBP3 in developing cardiac fibrosis. Silencing METTL3 could downregulate the expression of IGFBP3 and inhibit the activation of CFs and the degree of cardiac fibrosis both in vitro and in vivo. Indeed, we also verified the expression of METTL3 and IGFBP3 in the atrial tissues of patients with atrial fibrillation (AF). Thus, METTL3 may regulate IGFBP3's expression and CFs activation via RNA epigenetic modifications, laying the foundation for a specific and novel therapeutic target in cardiac fibrosis.

Hsa_circ_0000877 facilitates the progression of diffuse large B-cell lymphoma by miR-370-3p/mitogen-activated protein kinase kinase kinase kinase 4/Hippo pathway

Diffuse large B-cell lymphoma (DLBCL) originates from B lymphocytes and is a fatal hematological malignancy. Circular RNAs have been increasingly reported as a promising biological target for cancer therapy, but their role in DLBCL remains poorly studied. Relative expression levels of has_circ_0000877 (circ_0000877), microRNA-370-3p (miR-370-3p), and mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) were assessed by quantitative real-time PCR. Western blot analysis was employed to measure protein levels. Cell Counting Kit-8 assay and 5-ethynyl-2'-deoxyuridine (EdU) assay were used to detect the proliferation of TMD8 and U2932 cells. Cell cycle and apoptosis were investigated by flow cytometry. Transwell assay was used to analyze cell migration and invasion. Molecular interaction was determined by dual-luciferase reporter assay and RNA immunoprecipitation assay. The protein expression of Ki67 in tumor tissues of mice was detected by immunohistochemistry assay. The expression of circ_0000877 was markedly elevated in DLBCL tissues and cell lines. The decreased expression of circ_0000877 significantly inhibited proliferation, migration, and invasion of DLBCL cell lines. In addition, silencing circ_0000877 promoted cell apoptosis and induced cell cycle arrest in G0/G1 phase. Then, miR-370-3p directly interacted with circ_0000877 and MAP4K4. Circ_0000877 promoted MAP4K4 level by sponging miR-370-3p. MAP4K4 depletion inhibited the activation of Hippo pathway. Finally, circ_0000877 silencing significantly prevented the growth of DLBCL cells in vivo . Our findings revealed that circ_0000877 could regulate the malignant evolution of DLBCL by miR-370-3p/MAP4K4/Hippo pathway.

Insight into LncRNA- and CircRNA-Mediated CeRNAs: Regulatory Network and Implications in Nasopharyngeal Carcinoma—A Narrative Literature Review

Nasopharyngeal carcinoma (NPC) is a kind of head-and-neck malignant tumor, and distant metastasis treatment resistance is the leading cause of patient death. In-depth understanding of NPC progression and treatment failure remains to be explored. Long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) are noncoding RNAs that play key regulatory role in shaping tumor cell activities. Recent studies have revealed that lncRNA and circRNA function as competitive endogenous RNAs (ceRNAs) by regulating the posttranscriptional expression of genes as miRNA baits. The imbalanced ceRNA networks derived from lncRNA/circRNA-miRNA-mRNA interaction are widely found to contribute to NPC development. Herein, we summarize typical examples of lncRNA/circRNA-associated ceRNAs in recent years, which involved the potential molecular mechanisms in the regulation of proliferation, apoptosis, treatment resistance and metastasis of NPC, and discuss their potential clinical significance in the prognosis and treatment of NPC. Interpreting the involvement of ceRNAs networks will provide new insight into the pathogenesis and treatment strategies of NPC. However, ceRNA regulatory mechanism has some limitations currently. Screening the most effective ceRNA targets and the clinical application of ceRNA still has many challenges.

Identification of the regulatory role of the circ_0004788/miR-515-5p/FGF2 network in nasopharyngeal carcinoma development

BACKGROUND

CircularRNAs (circRNAs) played vital roles in nasopharyngeal carcinoma (NPC). However, the impacts of circ_0004788 on the development of NPC have not been explored.

METHODS

Cell counting kit-8 (CCK-8), 5-Ethynyl-2'-deoxyuridine (EdU) and colony formation assays were applied to determine cell proliferation. Wound healing, transwell invasion assay, tube formation assay, and flow cytometry were employed for the detection of cell migration, invasion, angiogenesis, and apoptosis, respectively. Xenograft tumor experiment was used to explore the biological role of circ_0004788 in NPC in vivo.

RESULTS

Circ_0004788 and fibroblast growth factor 2 (FGF2) were significantly elevated, and microRNA-515-5p (miR-515-5p) was dramatically decreased in NPC tissues and cells. The impacts of circ_0004788 knockdown on cell progression in NPC cells were reversed by miR-515-5p inhibitor, and FGF2 overexpression could block the suppressive effect of miR-515-5p on cell progression in NPC cells.

CONCLUSION

Circ_0004788 knockdown restrained the progression of NPC via the miR-515-5p/FGF2 axis.

Novel Plasma Proteomic Biomarkers for Early Identification of Induction Chemotherapy Beneficiaries in Locoregionally Advanced Nasopharyngeal Carcinoma

Background

Induction chemotherapy (IC) can alleviate locoregionally advanced nasopharyngeal carcinoma (LA-NPC), but effectiveness differs between patients, toxicity is problematic, and effective blood-based IC efficacy predictors are lacking. Here, we aimed to identify biomarkers for early identification of IC beneficiaries.

Methods

Sixty-four pairs of matched plasma samples collected before and after IC from LA-NPC patients including 34 responders and 30 non-responders, as well as 50 plasma samples of healthy individuals, were tested using data-independent acquisition mass spectrometry. The proteins associated with clinical traits or IC benefits were investigated by weighted gene co-expression network analysis (WGCNA) and soft cluster analysis. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional annotations were performed to determine the potential function of the identified proteins. The area under the receiver operating characteristic curve (AUC) was used to evaluate the performance of candidate biomarkers in predicting IC beneficiaries.

Results

Compared with healthy individuals, 1027 differentially expressed proteins (DEPs) were found in the plasma of LA-NPC patients. Based on feedback from IC outcomes, 463 DEPs were identified in the pre-IC plasma between responders and non-responders. A total of 1212 DEPs represented the proteomic changes before and after IC in responders, while 276 DEPs were identified in post-IC plasma between responders and non-responders. WGCNA identified nine protein co-expression modules correlated with clinical traits. Soft cluster analysis identified four IC benefits-related protein clusters. Functional enrichment analysis showed that these proteins may play a role in IC via immunity, complement, coagulation, glycosaminoglycan and serine. Four proteins differentially expressed in all group comparisons, paraoxonase/arylesterase 1 (PON1), insulin-like growth factor-binding protein 3 (IGFBP-3), rheumatoid factor D5 light chain (v-kappa-3) and RNA helicase (DDX55), were associated with clinical traits or IC benefits. A four-protein model accurately identified potential IC beneficiaries (AUC=0.95) while diagnosing LA-NPC (AUC=0.92), and the prediction performance was verified using the models to confirm the effective IC (AUC=0.97) and evaluate IC outcome (AUC=0.94).

Conclusion

The plasma protein profiles among IC responders and non-responders were different. PON1, IGFBP3, v-kappa-3 and DDX55 could serve as potential biomarkers for early identification of IC beneficiaries for individualised treatment of LA-NPC.

Noncoding RNA actions through IGFs and IGF binding proteins in cancer

The insulin-like growth factors (IGFs) and their regulatory proteins—IGF receptors and binding proteins—are strongly implicated in cancer progression and modulate cell survival and proliferation, migration, angiogenesis and metastasis. By regulating the bioavailability of the type-1 IGF receptor (IGF1R) ligands, IGF-1 and IGF-2, the IGF binding proteins (IGFBP-1 to -6) play essential roles in cancer progression. IGFBPs also influence cell communications through pathways that are independent of IGF1R activation. Noncoding RNAs (ncRNAs), which encompass a variety of RNA types including microRNAs (miRNAs) and long-noncoding RNAs (lncRNAs), have roles in multiple oncogenic pathways, but their many points of intersection with IGF axis functions remain to be fully explored. This review examines the functional interactions of miRNAs and lncRNAs with IGFs and their binding proteins in cancer, and reveals how the IGF axis may mediate ncRNA actions that promote or suppress cancer. A better understanding of the links between ncRNA and IGF pathways may suggest new avenues for prognosis and therapeutic intervention in cancer. Further, by exploring examples of intersecting ncRNA-IGF pathways in non-cancer conditions, it is proposed that new opportunities for future discovery in cancer control may be generated.

Circular RNA circ_0005835 promotes promoted neural stem cells proliferation and differentiate to neuron and inhibits inflammatory cytokines levels through miR-576-3p in Alzheimer's disease

Alzheimer's disease (AD) is the most frequent neurodegenerative disease and it is difficult to have an effective and simple method for AD early diagnosis. CircRNAs (circular RNAs) are novel discovered non-coding endogenous RNAs that affect cell apoptosis, differentiation, growth, metabolism, and metastasis. Recently, it has reported that circ_0005835 was one upregulated circRNA in the AD patients. However, the function role of circ_0005835 remains unknown. In our study, we found that circ_0005835 was upregulated in AD patients and cell models. Knockdown of circ_0005835 could downregulate neuroinflammation in BV2 cells. Moreover, knockdown of circ_0005835 promoted neural stem cells (NSC) proliferation and differentiate to neuron. These data mean that circ_0005835 plays important role in the development of AD. The miR-576-3p expression in serum was downregulated in the AD group compared to the health control group. Consistently, the level of circ_0005835 was overexpressed in the Aβ-treated in both SH-SY5Y and BV2 cells. Moreover, the expression of miR-576-3p was negatively correlated with circ_0005835 in AD patients. In addition, we performed the rescued experiments to show that knockdown of circ_0005835 could downregulate neuroinflammation through sponging miR-576-3p in BV2 cells. Inhibition of circ_0005835 promoted NSC proliferation and differentiate to neuron via sponging miR-576-3p. These data suggested that circ_0005835 promoted AD development through regulating miR-576-3p expression.

CircTMTC1 contributes to nasopharyngeal carcinoma progression through targeting miR-495-MET-eIF4G1 translational regulation axis

Nasopharyngeal carcinoma (NPC) is the most common primary malignancy arising from the epithelial cells of nasopharynx. CircTMTC1 is upregulated in NPC patients, but its role and molecular mechanism in NPC are unknown. Normal nasopharyngeal epithelium and tumor tissues were collected. The expression of circTMTC1, miR-495, MET/eIF4G1 pathway-related molecules were examined. Colony formation and transwell assays were used to assess cell proliferation, migration, and invasion. Cell apoptosis was analyzed by annexin V and propidium iodide (PI) staining. Gene interaction was examined by RNA immunoprecipitation (RIP) and luciferase activity assays. Subcutaneous and intravenous xenograft mouse models were established to analyze NPC growth and metastasis in vivo. CircTMTC1 was highly expressed and miR-495 was downregulated in NPC, which were associated with poor prognosis of NPC. Both circTMTC1 knockdown and miR-495 overexpression inhibited NPC cell proliferation, migration, invasion, and epithelial–mesenchymal transition (EMT) and promoted cell apoptosis. CircTMTC1 directly targeted miR-495 to promote the expression of its downstream target gene MET. miR-495 knockdown enhanced the expression of c-Myc, Cyclin D1, and survivin and accelerated NPC cell proliferation, migration, invasion, and EMT through targeting MET and activating the MET-eIF4G1 axis. CircTMTC1 silence inhibited NPC growth and lung metastasis by targeting the miR-495-MET-eIF4G1 translational regulation axis in vivo. CircTMTC1 accelerates NPC progression through targeting miR-495 and consequently activating the MET-eIF4G1 translational regulation axis, suggesting potential therapeutic targets for NPC treatment.

Splicing factor derived circular RNA circCAMSAP1 accelerates nasopharyngeal carcinoma tumorigenesis via a SERPINH1/c-Myc positive feedback loop

Background

Circular RNAs play an important role in tumor genesis and progression, but they have not been sufficiently studied in patients with nasopharyngeal carcinoma (NPC).

Methods

The circular RNA, circCAMSAP1, was screened in NPC cells by RNA sequencing analysis. The expression of circCAMSAP1 in NPC tissues was examined by real-time quantitative polymerase chain reaction (RT-qPCR) and in situ hybridization. Wound-healing, transwell, MTT and flow cytometry assays, and nude mouse tumor models were used to explore the effect of circCAMSAP1 on proliferation and metastasis of NPC in vitro or in vivo. The downstream proteins regulated by circCAMSAP1 were screened using mass spectrometry. The interaction between circCAMSAP1 and the SERPINH1 mRNA was identified using the circular RNA immunoprecipitation method and the luciferase reporter assay. The interaction between SERPINH1 and transcription factor c-Myc was verified through Co-immunoprecipitation (Co-IP) and immunofluorescence. The effect of c-Myc on the generation of circCAMSAP1 was examined through RT-qPCR and chromatin immunoprecipitation. Finally, the splicing factors that promote the production of circCAMSAP1 were explored by RT-qPCR and RNA immunoprecipitation (RIP).

Results

We found that circCAMSAP1 was highly expressed in NPC tissues and promoted NPC proliferation and metastasis. Additionally, circCAMSAP1 promoted SERPINH1 expression through improved SERPINH1 mRNA stability by binding to the 3′-untranslated region (3’UTR) of SERPINH1. Highly expressed SERPINH1 reduced the ubiquitination-degradation rate of c-Myc, causing increased tumorigenesis. Meanwhile, c-Myc, cooperating with splicing factor 10 (SRSF10), could also promote CAMSAP1 pre-mRNA transcription and back-splicing, forming a positive feedback of circCAMSAP1 production, resulting in the proliferation and metastasis of NPC.

Conclusions

Our findings revealed that circCAMSAP1 promotes NPC proliferation and metastasis by binding to the 3’UTR of SERPINH1, suggesting that the positive feedback of circCAMSAP1-SERPINH1-c-Myc may serve as a prognostic biomarker or therapeutic target in patients with NPC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01502-2.

Knockdown of circHECTD1 inhibits oxygen-glucose deprivation and reperfusion induced endothelial-mesenchymal transition

Ischemic stroke (IS) has become a cerebrovascular disease which seriously threatens the elderly people. It has been reported that circRNAs participate in multiple diseases, including IS. However, the role of circHECTD1 in IS remains largely unknown. To mimic IS in vitro, human cerebral microvascular endothelial cells (HCMECs) were treated with oxygen glucose deprivation/reperfusion (OGD/R). Meanwhile, MCAO mouse model was established to detect the expression of circHECTD1 in IS. qRT-PCR and western blot were used to test gene and protein expressions, respectively. CCK-8 assay was used to investigate the cell viability. Moreover, cell migration and tube formation were assessed by transwell and tube formation assays. In addition, RIP and luciferase assay were performed to explore the association among circHECTD1, miR-335 and NOTCH2. CircHECTD1 was significantly upregulated in IS. OGD/R significantly induced EndoMT in HCMECs, while knockdown of circHECTD1 notably reversed this phenomenon. In addition, silencing of circHECTD1 remarkably reversed OGD/R-induced promotion of HCMEC tube formation and migration. Meanwhile, circHECTD1 upregulated the level of NOTCH2 through binding with miR-335. Furthermore, miR-335 inhibited the process of EndoMT in IS via targeting NOTCH2. In summary, circHECTD1 knockdown significantly alleviated EndoMT process in HCMECs via mediation of miR-335/NOTCH2 axis. Thus, circHECTD1 might act as a potential target against IS.

Hsa_circ_0007637 Facilitates Nasopharyngeal Carcinoma Progression by Sponging miR-636/TPD52 Axis

Purpose

Hsa_circ_0007637 was discovered to be differentially expressed in nasopharyngeal carcinoma (NPC). However, the exact function and mechanism of Hsa_circ_0007637 on NPC have not been studied. This study firstly researched the function and mechanism of Hsa_circ_0007637 on NPC progression.

Methods

Hsa_circ_0007637, miR-636 and TPD52 expressions in 80 NPC patients were detected by quantitative real-time polymerase chain reaction. Hsa_circ_0007637 effect on NPC cell proliferation, apopticosis, invasion and migration was investigated by cell counting kit-8 assay, flow cytometry, transwell experiment and wound healing assay accordingly. Dual-luciferase reporter gene assay, RNA immunoprecipitation experiment and RNA fluorescence in situ hybridization experiment were performed to identify the binding between Hsa_circ_0007637 and miR-636. Dual-luciferase reporter gene assay and RNA pull down assay were conducted to verify the binding between miR-636 and TPD52. TPD52 protein expression in NPC cells was determined by Western blot. In vivo study was performed using nude mice. Immunohistochemistry was performed to assess TPD52 and Ki67 expression in tissues.

Results

Hsa_circ_0007637 was overexpressed in NPC tissues and cells. High Hsa_circ_0007637 expression predicted a poor outcome for NPC patients. Hsa_circ_0007637 knockdown decreased proliferation, invasion, migration and increased apoptosis of NPC cells (P < 0.01). Hsa_circ_0007637 could enhance TPD52 expression via sponging miR-636. miR-636 overexpression or TPD52 knockdown weakened the promoting effect of Hsa_circ_0007637 on NPC cells malignant phenotype (P < 0.01). Hsa_circ_0007637 knockdown suppressed NPC cells growth in vivo (P < 0.01).

Conclusion

Hsa_circ_0007637 facilitates NPC progression by sponging miR-636/TPD52 axis.

Circular RNA circ_0008450 regulates the proliferation, migration, invasion, apoptosis and chemosensitivity of CDDP-resistant nasopharyngeal carcinoma cells by the miR-338-3p/SMAD5 axis

Circular RNAs have recently been implicated in the tumorigenesis and chemoresistance of nasopharyngeal carcinoma (NPC). In this report, we identified the precise action of circ_0008450 in NPC progression and cisplatin (CDDP) resistance. The levels of circ_0008450, microRNA (miR)-338-3p and SMAD family member 5 (SMAD5) were gauged by quantitative real-time PCR or western blot. Cell proliferation and IC50 value for CDDP were detected by the Cell Counting Kit-8 assay. Cell colony formation, cell cycle progression, apoptosis, migration and invasion were assessed by colony formation, flow cytometry and transwell assays, respectively. Targeted relationships among circ_0008450, miR-338-3p and SMAD5 were determined by dual-luciferase reporter and RNA immunoprecipitation assays. Tumor models were assayed to evaluate the role of circ_0008450 in tumor growth. Our data indicated that up-regulated circ_0008450 was correlated with NPC CDDP resistance. Moreover, the knockdown of circ_0008450 suppressed cell proliferation, migration, invasion, and promoted apoptosis and CDDP sensitivity in vitro, as well as weakened tumor growth in vivo. Mechanistically, circ_0008450 directly bound to miR-338-3p, and the regulatory effects of circ_0008450 on cell malignant behaviors and CDDP sensitivity were mediated by miR-338-3p in vitro. SMAD5 was a direct target of miR-338-3p and circ_0008450 mediated SMAD5 expression through miR-338-3p. Furthermore, the enforced level of miR-338-3p regulated cell malignant behaviors and CDDP sensitivity in vitro via down-regulating SMAD5. Additionally, the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway was modulated by the circ_0008450/miR-338-3p axis in the two CDDP-resistant NPC cell lines. Our current study suggested that circ_0008450 modulated the malignant behaviors and drug sensitivity of CDDP-resistant NPC cells at least in part by targeting the miR-338-3p/SMAD5 axis, providing potential targets for improving the treatment of chemoresistant NPC.

CircN4BP2L2 promotes colorectal cancer growth and metastasis through regulation of the miR-340-5p/CXCR4 axis

Colorectal cancer (CRC) is the third leading cause of cancer-related death worldwide. Dysregulation of circular RNAs (circRNAs) appears to be a critical factor in CRC progression. However, mechanistic studies delineating the role of circRNAs in CRC remain limited. In this study, qRT-PCR and western blot assays were used to measure the expression of genes and proteins. Migration, invasion, proliferation, and apoptosis were examined by wound-healing, transwell, CCK-8, colony formation, and flow cytometry assays, respectively. Molecular interactions were validated by a dual-luciferase report system. A xenograft animal model was established to examine in vivo tumor growth and lung metastasis. Our data indicated that circN4BP2L2 expression was increased in CRC tissues and cell lines. Notably, inhibition of circN4BP2L2 effectively inhibited proliferation, migration, and invasion of LoVo cells, and inhibited tumor growth and metastasis in vivo, whereas the forced expression of circN4BP2L2 facilitated the proliferation, migration, and invasion of HT-29 cells. Mechanistic studies revealed that circN4BP2L2 acted as a molecular sponge of miR-340-5p to competitively promote CXCR4 expression. Furthermore, inhibition of miR-340-5p reversed the anti-cancer effects of circN4BP2L2 or CXCR4 silencing. Our data indicated an oncogenic role of circN4BP2L2 in CRC via regulation of the miR-340-5p/CXCR4 axis, which may be a promising biomarker and target for CRC treatment.

Circular RNAs: Functions and mechanisms in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant epithelial tumor of the nasopharyngeal mucosa with a high incidence rate in southern China and Southeast Asia and an evident ethnic and geographical distribution. Circular RNAs (circRNAs) are single-stranded noncoding RNAs with covalent, closed-loop structures. They are characterized by high stability and abundance, are evolutionarily conserved, and exhibit tissue/developmental stage specificity. Previous studies have shown that circRNAs are associated with the occurrence and development of various malignant tumors. However, the expression patterns and clinical significance of circRNAs in NPC remain ambiguous. Hence, the present review focuses on the biogenesis and regulation of circRNAs, and the functional roles of abnormally expressed circRNAs in NPC. In addition, the current review discusses the possibility of utilizing circRNAs as potential clinical biomarkers for the diagnosis and prognosis of NPC.

Circ_0000215 Exerts Oncogenic Function in Nasopharyngeal Carcinoma by Targeting miR-512-5p

Background: Increasing circular RNAs (circRNAs) are reported to participate in cancer progression. Nonetheless, the role of circRNAs in nasopharyngeal carcinoma (NPC) has not been fully clarified. This work is aimed to probe the role of circ_0000215 in NPC.

Methods: Circ_0000215 expression in NPC tissues and cell lines was examined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell counting kit-8 (CCK-8) assay, 5-bromo-2′-deoxyuridine (BrdU) assay, scratch healing assay and Transwell experiment were executed to investigate the regulatory function of circ_0000215 on the proliferation, migration and invasion of NPC cells. RNA immunoprecipitation (RIP), pull-down and dual-luciferase reporter experiments were utilized to determine the binding relationship between circ_0000215 and miR-512-5p, and between miR-512-5p and phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1) 3′UTR. The effects of circ_0000215 on NPC growth and metastasis in vivo were examined with nude mice model. Western blot was applied to detect the regulatory effects of circ_0000215 and miR-512-5p on PIK3R1 expression.

Results: Circ_0000215 was overexpressed in NPC tissues and cell lines. The functional experiments confirmed that knockdown of circ_0000215 impeded the growth and metastasis of NPC cells in vitro and in vivo. Additionally, circ_0000215 could also work as a molecular sponge to repress miR-512-5p expression. PIK3R1 was validated as a target gene of miR-512-5p, and circ_0000215 could increase the expression level of PIK3R1 in NPC cells via suppressing miR-512-5p.

Conclusion: Circ_0000215 is overexpressed in NPC and exerts oncogenic effects in NPC through regulating miR-512-5p/PIK3R1 axis.

Long Non-coding RNA LINC01503 Promotes Gastric Cardia Adenocarcinoma Progression via miR-133a-5p/VIM Axis and EMT Process

BACKGROUND

LINC01503 has been reported to act as a candidate oncogenic lncRNA in several types of human cancer. However, the functions and underlying mechanisms of LINC01503 in gastric cardia adenocarcinoma (GCA) remain unclear.

AIMS

To investigate the roles and underlying mechanisms of LINC01503 in GCA progression.

MATERIALS AND METHODS

Gene expressions were detected by quantitative real-time PCR (qRT-PCR). Gain-of-function assays were performed to evaluate the function of LINC01503 in gastric cancer cells. Bioinformatics analysis, luciferase reporter assay, and RIP assay were performed to identify associations among LINC01503, miR-133a-5p, and VIM.

RESULTS

The expression level of LINC01503 was significantly elevated in GCA tissues and cell lines. High expression of LINC01503 was correlated with lymph node metastasis, TNM stage, and poor prognosis of GCA patients. Knockdown of LINC01503 significantly reduced proliferation, migration, and invasion ability in GC cells. LINC01503 might function as a competing endogenous RNA (ceRNA) via sponging miR-133a-5p to upregulate the expression of VIM. Furthermore, overexpression of LINC01503 promoted the progression of epithelial mesenchymal transition (EMT) in vitro.

CONCLUSION

LINC01503 serves as an oncogenic lncRNA to promote GCA progression via affecting LINC01503/miR-133a-5p/VIM axis and EMT process. LINC01503 not only has a critical role in GCA progression but also provide a novel potential biomarker in predicting prognosis for GCA patients.

High SPIN4 Expression Is Linked to Advanced Nodal Status and Inferior Prognosis in Nasopharyngeal Carcinoma Patients

Nasopharyngeal carcinoma (NPC), characterized by the infiltration of lymphocytes, is a malignancy derived from the epithelium of the nasopharynx. Despite its sensitivity to radiation and chemotherapy, NPC has a high propensity for recurrence and metastasis. Although lymph node levels have been indicated as an independent prognostic factor for NPC, there has been no precise prognostic biomarker to predict clinical outcomes for NPC before advanced disease. In the present study, we surveyed differentially expressed genes in NPC via the next-generation sequencing (NGS)-based Oncomine database and identified the spindlin family member 4 (SPIN4) gene as the most relevant to advanced nodal status. We collected 124 tumor samples from NPC patients receiving biopsy, and the expression level of SPIN4 was evaluated by immunohistochemistry. The results showed that tumors with high SPIN4 expression were significantly correlated with advanced nodal status (p < 0.001) and advanced AJCC stages (p < 0.001). High SPIN4 expression in tumor samples was an unfavorable prognostic factor for all three endpoints at the univariate level: disease-specific survival (DSS), distal metastasis-free survival (DMeFS), and local recurrence-free survival (LRFS) (all p < 0.05). High SPIN4 expression remained independently prognostic of worse DMeFS (p = 0.049) at the multivariate level. Using bioinformatics analysis, we further found that high SPIN4 level may link tight junctions to cancer cell survival. Collectively, these results imply that high SPIN4 expression is linked to an aggressive clinical course, including advanced nodal status and poor survival in NPC patients, emphasizing the promising prognostic utility of SPIN4 expression.

Research Progress of circRNAs in Head and Neck Cancers

Circular RNAs (circRNAs) are a novel type of non-coding RNAs. Because of their characteristics of a closed loop structure, disease- and tissue-specificity, and high conservation and stability, circRNAs have the potential to be biomarkers for disease diagnosis. Head and neck cancers are one of the most common malignant tumors with high incidence rates globally. Affected patients are often diagnosed at the advanced stage with poor prognosis, owing to the concealment of anatomic sites. The characteristics, functions, and specific mechanisms of circRNAs in head and neck cancers are increasingly being discovered, and they have important clinical significance for the early diagnosis, treatment, and prognosis evaluation of patients with cancer. In this study, the generation, characteristics, and functions of circRNAs, along with their regulatory mechanisms in head and neck cancers have been summarized. We report that circRNAs interact with molecules such as transcription and growth factors to influence specific pathways involved in tumorigenesis. We conclude that circRNAs have an important role to play in the proliferation, invasion, metastasis, energy and substance metabolism, and treatment resistance in cancers.

KIF18A knockdown reduces proliferation, migration, invasion and enhances radiosensitivity of esophageal cancer

Kinesin family member 18A (KIF18A) is significantly overexpressed and is related to the poor prognosis of human cancers. However, the function of KIF18A in esophageal cancer (EC) is still unclear. Human EC cell lines were used in this study. KIF18A expression in human tissues was assessed using Gene Expression Profiling Interactive Analysis 2.0 (GEPIA2). The expressions of KIF18A or IGF2BP3 in EC cells were detected using qRT-PCR or WB. Cells were transfected using si-KIF18A, si-IGF2BP3, and plasmid IGF2BP3. The abilities of proliferation, migration, and invasion were detected by EdU, wound-healing, and transwell assay. The interaction between KIF18A and IGF2BP3 was predicted by starBase v3.0 and studied by RIP and RNA stability assay. Colony formation assay was used to reflect the changes of radiosensitivity in EC cells. KIF18A was upregulated in EC, and KIF18A knockdown inhibited EC cell proliferation, migration, invasion, and radioresistance. The prediction in starBase and RIP assay results showed that KIF18A mRNA could bind to IGF2BP3 protein in EC cells. RNA stability assay was performed to confirm that IGF2BP3 affects mRNA stability of KIF18A. Further studies also showed that IGF2BP3 could positively regulate KIF18A on proliferation, migration, invasion, and radioresistance. Our findings first revealed an oncogenic effect of KIF18A in human EC progression. KIF18A expression was associated with radioresistance of EC cells. The binding relationship between KIF18A and IGF2BP3 might influence the mRNA stability of KIF18A in EC cell lines.

Establishment and validation of a prognostic nomogram to predict early metastasis in nasopharyngeal carcinoma patients within six months after radiotherapy and to guide intensive treatment

PURPOSE

This study aimed to establish an effective prognostic nomogram to predict the risk of early metastasis (EM) in nasopharyngeal carcinoma (NPC) patients, as a guide for intensive treatment.

MATERIALS AND METHODS

A total of 9021 patients with biopsy-confirmed NPC at our institute were enrolled in this study between December 2006 to December 2016. We randomized these patients using a proportion of 2/3 and 1/3 and selected 6044 and 2977 patients as the training and validation cohorts, respectively. All patients received radiotherapy with or without chemotherapy. Univariate and multivariate logistical regressions were used to identify independent risk factors. The nomogram's predictive value was evaluated by concordance indexes (C-indexes), calibration curves, probability density functions (PDFs), and clinical utility curves (CUCs). ROC analysis using Delong test was used to compare efficiency between the nomogram and other risk factors.

RESULTS

In total, 174 (2.9%) and 81 (2.7%) patients in training and validation cohorts, respectively, had EM. Pretreatment plasma EBV DNA, N stage, LDH, ALP, BMI, and sex were independent predictive factors of EM. The C-indexes of nomogram were 0.756 (95% CI = 0.719-0.793) and 0.766 (95% CI = 0.720-0.813), in the training and validation cohorts, respectively. The C-index of the nomogram was significantly superior to any one of independent factors. According to the PDFs and CUCs and considering the balance of the true positive EM patients and true positive non-EM patients, we chose 5.0% as a threshold probability for clinical decision-making, which could distinguish about 85% and 48% of non-EM and EM patients, respectively.

CONCLUSION

Our nomogram had good accuracy in predicting EM incidence, and a 5.0% threshold was appropriate for clinical decision-making.

Circ_0000527 Promotes Retinoblastoma Progression through Modulating miR-98-5p/XIAP Pathway

Purpose: Retinoblastoma (RB) is an intraocular malignancy that often occurs in childhood. Circular RNAs (circRNAs) play crucial roles in regulating the malignant phenotypes of various tumors. This study aimed to explore the role and potential mechanism of circ_0000527 in RB.Methods: The levels of circ_0000527, microRNA-98-5p (miR-98-5p) and X-linked inhibitor of apoptosis (XIAP) were determined by qRT-PCR or western blot. Cell proliferation was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and colony formation assays. Cell apoptosis, migration and invasion were evaluated by flow cytometry, transwell and scratch assays. Xenograft assay was conducted to analyze tumor growth in vivo. The binding relationship between miR-98-5p and circ_0000527 or XIAP was verified by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays.Results: Circ_0000527 and XIAP levels were increased, while miR-98-5p level was reduced in RB tissues and cells. Silencing of circ_0000527 suppressed the proliferation, migration and invasion of RB cells and promoted apoptosis. In addition, knockdown of circ_0000527 inhibited tumor growth in xenograft mice. Besides, circ_0000527 sponged miR-98-5p to regulate RB cell progression, and miR-98-5p targeted XIAP to mediate RB cell development. Moreover, circ_0000527 modulated XIAP expression via sequestering miR-98-5p.Conclusion: Circ_0000527 facilitated RB progression via regulating miR-98-5p/XIAP axis, which provided a promising therapeutic target for RB.

CircNRIP1 Modulates the miR-515-5p/IL-25 Axis to Control 5-Fu and Cisplatin Resistance in Nasopharyngeal Carcinoma

Background

The development of drug resistance leads many NPC patients to experience disease relapse following the completion of chemotherapy. It is thus essential that the mechanistic basis for such chemoresistance be clarified in an effort to identify approaches to sensitizing NPC tumors to treatment with cisplatin and related agents.

Methods

A qRT-PCR approach was used to measure the expression of circNRIP1 in NPC, while luciferase assays were used to identify interactions with downstream targets of circNRIP1 activity including miR-515-5p and IL-25. CCK8 assays were also utilized to detect IC50 values for cisplatin and 5-Fu.

Results

The expression of circNRIP1 was significantly increased in the serum of chemoresistant NPC patients. At a functional level, we determined that circNRIP1 is able to sequester miR-515-5p, thereby inhibiting its ability to post-transcriptionally suppress IL-25 expression. We observed a significant negative correlation between the expression of miR-515-5p and circNRIP1 in serum samples from chemoresistant NPC patients, consistent with a functional interaction between these two factors. We further found that 5-Fu and CDDP IC50 values in NPC cells in which circNRIP1 had been knocked down were restored following miR-515-5p inhibitor transfection. Similarly, changes in these IC50 values were reversed in NPC cells transfected with miR-515-5p mimics following the overexpression of IL-25 in these same cells.

Conclusion

These data highlight the circNRIP1/miR-515-5p/IL-25 as a novel regulator of 5-Fu and cisplatin resistance in NPC, suggesting that this pathway may be amenable to therapeutic targeting as an approach to treating this cancer type.

Circ_0035483 Functions as a Tumor Promoter in Renal Cell Carcinoma via the miR-31-5p-Mediated HMGA1 Upregulation

Background

Renal cell carcinoma (RCC) that originates from the proximal renal tubules is the most common cancer of the human kidney. Increasing circRNA/miRNA/mRNA networks have been found in RCC regulation. This study will explore the regulatory relation of circular RNA (circRNA) circ_0035483, microRNA-31-5p (miR-31-5p) and high mobility group A1 (HMGA1).

Methods

The levels of circ_0035483, miR-31-5p and HMGA1 were measured by real-time polymerase chain reaction (qRT-PCR) or Western blot. Cell proliferation was determined using Cell Counting Kit-8 (CCK-8) and colony formation assays. Cell migration and invasion were assessed by transwell assay. HMGA1 and epithelial–mesenchymal transition (EMT)-related protein levels were quantified using Western blot. Glycolytic metabolism was evaluated by glucose consumption and lactate production. The interaction between targets was confirmed via dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays. In vivo experiment was performed through the establishment of xenograft models in mice.

Results

Circ_0035483 expression was upregulated in RCC tissues and cells. The inhibitory effects on RCC cell proliferation, migration, invasion, EMT and glycolysis were induced after circ_0035483 was downregulated. MiR-31-5p was identified as a target of circ_0035483 and miR-31-5p upregulation was related to the function of circ_0035483 knockdown in RCC cells. Additionally, miR-31-5p targeted HMGA1 and inhibited the malignant behaviors of RCC cells by negatively regulating HMGA1. Moreover, HMGA1 expression was regulated by circ_0035483 via targeting miR-31-5p. Circ_0035483 also affected tumor growth in vivo by relying on the miR-31-5p/HMGA1 axis.

Conclusion

These findings clarified that the tumor-promoting function of circ_0035483 in RCC was partly achieved by regulating the miR-31-5p/HMGA1 axis.

Circular RNA circ-CCAC1 Facilitates Adrenocortical Carcinoma Cell Proliferation, Migration, and Invasion through Regulating the miR-514a-5p/C22orf46 Axis

Adrenocortical carcinoma (ACC) is a rare but clinically aggressive endocrine malignancy. Circular RNAs (circRNAs) were found to play key roles in tumorigenesis. In the current study, we aimed to investigate the functions and mechanisms of a novel circRNA, circ-CCAC1, in ACC cells. circ-CCAC1 expression levels in ACC tissue specimens and cell lines were evaluated by RT-qPCR. Kaplan-Meier analysis was applied to explore the relationship between circ-CCAC1 and patients' prognosis. Cell counting kit-8 (CCK-8), colony formation, acridine orange/ethidium bromide (AO/EB) double fluorescence staining, and Transwell assays were performed to evaluate the functions of circ-CCAC1 in ACC cells. Bioinformatics analysis and a dual-luciferase reporter assay were utilized to explore the mechanisms of circ-CCAC1. As a result, circ-CCAC1 was overexpressed in ACC tissue samples and cell lines and correlated with poor prognosis. Gain- and loss-of-function tests demonstrated that circ-CCAC1 acted as an oncogene in ACC. What is more, circ-CCAC1 enhanced C22orf46 expression by sponging miR-514a-5p in ACC cells. A rescue assay illustrated that circ-CCAC1 facilitated ACC progression through miR-514a-5p/C22orf46 signaling. To sum up, we identified a novel circRNA, circ-CCAC1, which may be used as a potential therapeutic target for ACC.