CircRNA_100290 promotes GC cell proliferation and invasion via the miR-29b-3p/ITGA11 axis and is regulated by EIF4A3

Classical biomarkers and non-coding RNAs associated with diagnosis and treatment in gastric cancer

One of the most prevalent malignant tumors worldwide, stomach cancer still has a high incidence and fatality rate in China, and the number of young people developing early-onset gastric cancer is steadily increasing. The 5-year survival rate of stomach cancer is typically 30%-35%, the prognosis is bad, the patients' quality of life is low, and the progression of advanced gastric cancer cannot be effectively managed despite the use of surgical surgery, chemotherapy, and other medicines. We urgently need molecular biomarkers with high specificity and sensitivity to increase the early gastric cancer detection rate, extend patient survival, and improve patient quality of life. The initial diagnosis of gastric cancer primarily depends on gastroscopy and biopsy, and invasive procedures cause significant discomfort to patients. Similar to this, treating advanced and metastatic stomach cancer is a pressing issue that requires attention. More and more immune checkpoint molecules have been discovered, and corresponding inhibitors are gradually being applied to clinical diagnosis and treatment. Recently, some non-coding RNAs have begun to be used as new targets for the treatment of gastric cancer. Some non-coding RNAs are highly present in the serum or urine of gastric cancer patients and can be used as diagnostic markers or prognostic indicators. Many clinical trials targeting non-coding RNAs have also shown good therapeutic effects. In general, targeting non-coding RNAs has shown good therapeutic effects. The biomarkers for gastric cancer detection and treatment are reviewed in this article, focusing on the new non-coding RNAs used in diagnosis, prognosis, and treatment. Patients with stomach cancer should have access to more precise and efficient diagnosis and treatment choices as a result of ongoing technological advancements and thorough research.

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.

EIF4A3 Enhances the Proliferation and Cell Cycle Progression of Keloid Fibroblasts by Inducing the hsa_circ_0002198 Expression

Background

Recent evidence suggests a crucial biological role for Circular RNAs (circRNAs) in keloid diseases, yet the underlying mechanisms remain unclear. This study explored the biological effects and molecular mechanisms of hsa_circ_0002198 in keloid formation.

Methods

Real-time quantitative PCR (qRT-PCR) was employed to assess the expression of circ_0002198 in keloid tissues, normal skin tissues, keloid fibroblasts (KFs), and normal skin fibroblasts (NFs) from nine patients. To investigate the role of circ_0002198 in keloid pathogenesis, cell transfection technology was utilized to knock down circ_0002198. Various experiments including Cell Counting Kit-8 (CCK-8), 5-Ethynyl-2'-deoxyuridine (EdU), Transwell, wound healing assay, flow cytometry, and others were conducted to explore the potential mechanisms associated with circ_0002198 expression. The RNA-binding protein Eukaryotic translation initiation factor 4A, isoform 3 (EIF4A3) binding to circ_0002198 was identified and confirmed through bioinformatics databases prediction and RNA immunoprecipitation (RIP) assay. Finally, the expression of EIF4A3 was assessed, and both silencing and overexpression were employed to verify its role in circ_0002198 regulation.

Results

The expression levels of circ_0002198 and EIF4A3 were notably elevated in keloid tissues and KFs compared to normal skin tissues and NFs. The reduction of circ_0002198 expression in KFs significantly impeded their proliferation, migration, and invasion. It also hindered the cell cycle process and the expression of associated proteins while concurrently promoting apoptosis in KFs. EIF4A3 was identified to bind to the flanks of circ_0002198, enhancing the occurrence of circ_0002198 and its role in regulating the progression of KFs.

Conclusion

Our study offers insights into how Circular RNA may contribute to the pathogenesis of keloid formation, highlighting Circ_0002198 as a potential novel biomarker for keloids in association with EIF4A3. Further research, involving larger study cohorts, is necessary to broaden our understanding of keloid mechanisms and potential treatment approaches.

The potential of circular RNAs as biomarkers and therapeutic targets for gastric cancer: A comprehensive review

BACKGROUND

Gastric cancer (GC) is a global health concern, contributing significantly to cancer-related mortality rates. Early detection is vital for improving patient outcomes. Recently, circular RNAs (circRNAs) have emerged as crucial players in the development and progression of various cancers, including GC.

AIM

This comprehensive review underscores the promising potential of circRNAs as innovative biomarkers for the early diagnosis of GC, as well as their possible utility as therapeutic targets for this life-threatening disease. Specifically, the review focuses on recent findings, mechanistic insights, and clinical applications of circRNAs in GC.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Dysregulation of circRNAs has been consistently observed in GC tissues, offering potential diagnostic value due to their stability in bodily fluids such as blood and urine. For instance, circPTPN22 and hsa_circ_000200. Furthermore, the expression levels of circRNAs such as circCUL2, hsa_circ_0000705 and circSHKBP1 have shown strong associations with critical clinical features of GC, including diagnosis, prognosis, tumor size, lymph node metastasis, tumor-node-metastasis (TNM) stage, and treatment response. Additionally, circRNAs such as circBGN, circLMO7, and circMAP7D1 have shown interactions with specific microRNAs (miRNAs), proteins, and other molecules that play key roles in development and progression of GC. This further highlighting their potential as therapeutic targets. Despite their potential, several challenges need to be addressed to effectively apply circRNAs as GC biomarkers. These include standardizing detection methods, establishing cutoff values for diagnostic accuracy, and validating findings in larger patient cohorts. Moreover, the functional mechanisms by which circRNAs contribute to GC pathogenesis and therapeutic resistance warrant further investigation. Advances in circRNAs research could provide valuable insights into the early detection and targeted treatment of GC, ultimately improving patient outcomes.

The crosstalk between alternative splicing and circular RNA in cancer: pathogenic insights and therapeutic implications

RNA splicing is a fundamental step of gene expression. While constitutive splicing removes introns and joins exons unbiasedly, alternative splicing (AS) selectively determines the assembly of exons and introns to generate RNA variants corresponding to the same transcript. The biogenesis of circular RNAs (circRNAs) is inextricably associated with AS. Back-splicing, the biogenic process of circRNA, is a special form of AS. In cancer, both AS and circRNA deviate from the original track. In the present review, we delve into the intricate interplay between AS and circRNAs in the context of cancer. The relationship between AS and circRNAs is intricate, where AS modulates the biogenesis of circRNAs and circRNAs in return regulate AS events. Beyond that, epigenetic and posttranscriptional modifications concurrently regulate AS and circRNAs. On the basis of this modality, we summarize current knowledge on how splicing factors and other RNA binding proteins regulate circRNA biogenesis, and how circRNAs interact with splicing factors to influence AS events. Specifically, the feedback loop regulation between circRNAs and AS events contributes greatly to oncogenesis and cancer progression. In summary, resolving the crosstalk between AS and circRNA will not only provide better insight into cancer biology but also provoke novel strategies to combat cancer.

Radiation-sensitive circRNA hsa_circ_0096498 inhibits radiation-induced liver fibrosis by suppressing EIF4A3 nuclear translocation to decrease CDC42 expression in hepatic stellate cells

BACKGROUND

Radiation-induced liver fibrosis (RILF) is a common manifestation of radiation-induced liver injury (RILI) and is caused primarily by activated hepatic stellate cells (HSCs). Circular RNAs (circRNAs) play critical roles in various diseases, but little is known about the function and mechanism of circRNAs in RILF.

METHODS

RNA pull-down and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to screen binding proteins of hsa_circ_0096498 (circ96498). RNA-binding protein immunoprecipitation, RNA pull-down and nuclear and cytoplasmic protein extraction were conducted to confirm the interaction between circ96498 and eukaryotic initiation factor 4A3 (EIF4A3). RNA sequencing was performed to screen target genes regulated by EIF4A3. HSCs with altered circ96498 and cell division cycle 42 (CDC42) expression were used to assess irradiated HSC activation. Circ96498 inhibition and CDC42 blockade were evaluated in RILF mouse models.

RESULTS

In this study, we identified a radiation-sensitive circ96498, which was highly expressed in the irradiated HSCs of paracancerous tissues from RILI patients. Circ96498 inhibited the proliferation but promoted the apoptosis of irradiated HSCs, suppressed the secretion of proinflammatory cytokines IL-1β, IL-6 and TNF-α, and decreased the expression of profibrotic markers (α-SMA and collagen 1) in irradiated HSCs. Mechanistically, irradiation induced the transport of EIF4A3 into the nucleus, and nuclear EIF4A3 increased the stability of CDC42 mRNA and increased CDC42 expression, thereby promoting HSC activation through the NF-κB and JNK/Smad2 pathways. However, the binding of circ96498 to EIF4A3 impeded the translocation of EIF4A3 into the nucleus, resulting in the inhibition of CDC42 expression and subsequent HSC activation. Furthermore, circ96498 knockdown promoted the development of the early and late stages of RILF in a mouse model, which was mitigated by CDC42 blockade.

CONCLUSIONS

Collectively, our findings elucidate the involvement of the circ96498/EIF4A3/CDC42 axis in inhibiting irradiated HSC activation, which offers a novel approach for RILF prevention and treatment.

circE2F1-encoded peptide inhibits circadian machinery essential for nucleotide biosynthesis and tumor progression via repressing SPIB/E2F1 axis

Circadian clock dominates a variety of biological activities, while its roles and regulatory mechanisms in neuroblastoma (NB), a pediatric extracranial malignancy, still remain largely elusive. Herein, through comprehensive analyses of public datasets, E2F transcription factor 1 (E2F1) and its circular RNA (circE2F1)-encoded 99-amino acid peptide (E2F1-99aa) were identified as vital regulators of circadian machinery essential for purine and pyrimidine biosynthesis during NB progression. Mechanistically, through interaction with Spi-B transcription factor (SPIB), E2F1 was transactivated to up-regulate circadian machinery genes (CRY1 and TIMELESS), resulting in relief of CLOCK/BMAL1-repressed transcription of enzymes (DHODH, PAICS, or PPAT) essential for de novo purine and pyrimidine biosynthesis. The biogenesis of circE2F1 was repressed by eukaryotic translation initiation factor 4A3 (EIF4A3), while E2F1-99aa or its truncated peptide competitively bound to SPIB, leading to decrease in SPIB-E2F1 interaction, circadian machinery and nucleotide biosynthetic gene expression, purine or pyrimidine biosynthesis, tumorigenesis, and aggresiveness of NB cells. In clinical NB cases, high EIF4A3, E2F1 or SPIB expression was correlated with low survival possibility of patients, while lower circE2F1 or E2F1-99aa levels were associated with advanced stages and tumor progression. These results indicate that circE2F1-encoded peptide inhibits circadian machinery essential for nucleotide biosynthesis and tumor progression via repressing SPIB/E2F1 axis.

The molecular mechanism of naringin improving endometrial receptivity of OHSS rats

Controlling ovarian hyperstimulation syndrome (OHSS) in the controlled ovarian hyperstimulation treatment is necessary to increase the implantation success rate. This study aimed to explore the effect of naringin on the endometrial receptivity of OHSS rats. Female rats were randomly assigned to six groups: Blank, model, low-dose naringin (100 mg/kg/day), medium-dose naringin (200 mg/kg/day), high-dose naringin (400 mg/kg/day), and positive (0.18 mg/kg/day estradiol valerate) groups. Except for the blank group, rats established the OHSS model on Day 7, and their treatments were from Day 0 to 14, separately. Hematoxylin and eosin, immunohistochemical, and scanning electron microscopy were performed to detect the naringin effects on the endometrial receptivity of the OHSS model. Next, circRNAs transcriptome analysis was performed to screen circRNAs. Western blot analysis and real-time quantitative PCR were used to verify it. Our study showed that naringin treatments increased embryo number, endometrial thickness, pinopodes number, and Ki67 expression in the OHSS rats. Moreover, the result of circRNAs transcriptome sequencing showed that naringin significantly inhibited the rnocirc_008140 expression in the OHSS rats and significantly inhibited the changes of 28 gene ontology terms and three Kyoto Encyclopedia of Genes and Genomes pathways which were induced by OHSS. Abcc4 and Rps6ka5 genes were the enriched genes of those pathways. Finally, 24 miRNA target genes of rnocirc_008140 were predicted. Our study showed that naringin significantly improved the endometrial receptivity of OHSS rats to increase the embryo implantation success by reducing rnocirc_008140-adsorbed miRNAs to regulate Abcc4 and Rps6ka5 expression.

Extracellular vesicle-delivered hsa_circ_0090081 regulated by EIF4A3 enhances gastric cancer tumorigenesis

BACKGROUND

Circular RNA (circRNA) and extracellular vesicles (EVs) in tumors are crucial for the malignant phenotype of tumor cells. Nevertheless, the mechanisms and clinical effects of EV-delivered hsa_circ_0090081 in gastric cancer (GC) are unclear. This study aimed to reveal the effect of eukaryotic translation initiation factor 4A3 (EIF4A3)-mediated hsa_circ_0090081 expression and EV-delivered hsa_circ_0090081 on GC progression.

METHODS

qRT-PCR was conducted to clarify hsa_circ_0090081 and EIF4A3 levels in GC tissues. Transmission electronic microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blotting identified the EVs isolated from GC cells by ultracentrifugation. The roles of hsa_circ_0090081, EIF4A3, and EV-delivered hsa_circ_0090081 in GC cells were analyzed using Transwell, EdU, and CCK-8 assays. The regulatory role between EIF4A3 and hsa_circ_0090081 was investigated using RIP, qRT-PCR, and Pearson's analysis.

RESULTS

Our study showed that hsa_circ_0090081 and EIF4A3 were highly expressed in GC, and hsa_circ_0090081 was associated with poor prognosis. Data revealed that hsa_circ_0090081 inhibition restrained GC cell proliferation, invasion, and migration. Additionally, EIF4A3 could bind to the pre-mRNA of PHEX (linear form of hsa_circ_0090081) to enhance hsa_circ_0090081 expression in GC cells. Moreover, EIF4A3 overexpression nullified the malignant phenotypic suppression caused by hsa_circ_0090081 silencing in GC cells. Furthermore, EVs secreted by GC cells delivered hsa_circ_0090081 to facilitate the malignant progression of targeted GC cells.

CONCLUSION

This study showed that hsa_circ_0090081 was enhanced by EIF4A3 to play a promotive role in GC development. The results may help understand the mechanism of EIF4A3 and EV-delivered hsa_circ_0090081 and offer a valuable GC therapeutic target.

EIF4A3-Bound hsa_circ_0006847 Exerts a Tumor-Suppressive Role in Gastric Cancer

Numerous studies have shown that circular RNAs are associated with the occurrence and development of various cancers, but the biological functions and mechanisms of hsa_circ_0006847 (circASPHD1) in gastric cancer (GC) remain unclear. The expression of hsa_circ_0006847 in GC cell lines, tissue, and plasma from GC patients was assayed by quantitative real-time reverse transcription-polymerase chain reaction. Hsa_circ_0006847 expression in cells was downregulated or upregulated by transfected small interfering RNA (siRNA) or overexpression plasmid. The role of hsa_circ_0006847 in GC was investigated with Cell Counting Kit-8, EdU, Transwell, flow cytometry assays, and in a subcutaneous xenograft tumor model. In addition, the interaction of eukaryotic translation initiation factor 4A3 (EIF4A3) and hsa_circ_0006847 was determined with western blot, biotin-labeled RNA pull-down, and RNA immunoprecipitation assays. Co-immunoprecipitation and mass spectrometry were used to validate the combination of EIF4A3 and synaptopodin-2 (SYNPO2). The expression of hsa_circ_0006847 was decreased in GC tissues and cells and indicated poor survival and prognosis. Overexpression of hsa_circ_0006847 inhibited cell proliferation, migration, and invasion. Flow cytometry showed that upregulation of hsa_circ_0006847 resulted in promotion of apoptosis of GC cells and inhibited their progression through the G0/G1 phase. Downregulation of hsa_circ_0006847 expression had the opposite effects. Overexpression of hsa_circ_0006847 in subcutaneous tumor xenografts inhibited tumor growth. Mechanically, hsa_circ_0006847 promoted the binding of EIF4A3 to SYNPO2 by recruiting EIF4A3, which inhibited the growth of GC. The tumor suppressor activity of hsa_circ_0006847, inhibition of the occurrence and development of GC, was mediated by promotion of EIF4A3 and the binding of EIF4A3 to SYNPO2. The results support the study of hsa_circ_0006847 as a novel therapeutic target for the treatment of GC.

Effect of GLIS1 on the Lymph Node Metastasis of Cervical Squamous Carcinoma Based on Transcriptome Analysis

Cervical cancer remains the leading cause of cancer-related mortality among female reproductive malignancies, and lymph node metastasis (LNM) represents the major reason for its poor prognosis. In this study, we aimed to identify transcriptome differences in patients with cervical squamous cell carcinoma (CSCC) who developed LNM or not and to outline the function of GLIS1 in determining metastatic fate in CSCC. In The Cancer Genome Atlas-endocervical adenocarcinoma project, patients with LNM had shorter overall survival than those without. Transcriptome data from CSCC patients with and without LNM were analyzed to screen for differentially expressed genes (DEGs). DEGs were enriched in metastasis-related pathways, such as extracellular matrix organization, cell-cell adhesion, and regulation of tissue remodeling. GLIS1 was overexpressed in tumor tissues of patients with LNM. COMP and ITGA11 were screened as downstream targets of GLIS1. GLIS1 promoted their transcription by binding to the promoter regions of COMP and ITGA11. GLIS1 enhanced the migration, invasion, and epithelial-mesenchymal transition in CSCC cells, while the knockdown of COMP or ITGA11 reversed the promotion of GLIS1 on CSCC cell malignant phenotype. Together, our results demonstrate that GLIS1 might be related to the LNM of CSCC patients via COMP and ITGA11.

KRT17 From Keratinocytes With High Glucose Stimulation Inhibit Dermal Fibroblasts Migration Through Integrin α11

Objective

To investigate the effects of overexpressed keratin 17 (KRT17) on the biology of human dermal fibroblasts (HDFs) and to explore the mechanism of KRT17 in diabetic wound healing.

Methods

KRT17 expression was tested in diabetic keratinocytes, animal models, and patient skin tissues (Huazhong University of Science and Technology Ethics Committee, [2022] No. 3110). Subsequently, HDFs were stimulated with different concentrations of KRT17 in vitro. Changes in the proliferation and migration of HDFs were observed. Then, identification of KRT17-induced changes in dermal fibroblast of RNA sequencing-based transcriptome analysis was performed.

Results

KRT17 expression was upregulated under pathological conditions. In vitro stimulation of HDFs with different concentrations of KRT17 inhibited cell migration. RNA-seq data showed that enriched GO terms were extracellular matrix components and their regulation. KEGG analysis revealed that the highest number of enriched genes was PI3K-Akt, in which integrin alpha-11 (ITGA11) mRNA, a key molecule that regulates cell migration, was significantly downregulated. Decreased ITGA11 expression was observed after stimulation of HDFs with KRT17 in vitro.

Conclusion

Increased expression of KRT17 in diabetic pathological surroundings inhibits fibroblast migration by downregulating the expression of ITGA11. Thus, KRT17 may be a molecular target for the treatment of diabetic wounds.

miRNA/epithelial-mesenchymal axis (EMT) axis as a key player in cancer progression and metastasis: A focus on gastric and bladder cancers

The metastasis a major hallmark of tumors that its significant is not only related to the basic research, but clinical investigations have revealed that majority of cancer deaths are due to the metastasis. The metastasis of tumor cells is significantly increased due to EMT mechanism and therefore, inhibition of EMT can reduce biological behaviors of tumor cells and improve the survival rate of patients. One of the gaps related to cancer metastasis is lack of specific focus on the EMT regulation in certain types of tumor cells. The gastric and bladder cancers are considered as two main reasons of death among patients in clinical level. Herein, the role of EMT in regulation of their progression is evaluated with a focus on the function of miRNAs. The inhibition/induction of EMT in these cancers and their ability in modulation of EMT-related factors including ZEB1/2 proteins, TGF-β, Snail and cadherin proteins are discussed. Moreover, lncRNAs and circRNAs in crosstalk of miRNA/EMT regulation in these tumors are discussed and final impact on cancer metastasis and response of tumor cells to the chemotherapy is evaluated. Moreover, the impact of miRNAs transferred by exosomes in regulation of EMT in these cancers are discussed.

Circ_0067934: a circular RNA with roles in human cancer

A circular RNA (circRNA) is a non-coding RNA (ncRNA) derived from reverse splicing from pre-mRNA and is characterized by the absence of a cap structure at the 5' end and a poly-adenylated tail at the 3' end. Owing to the development of RNA sequencing and bioinformatics approaches in recent years, the important clinical value of circRNAs has been increasingly revealed. Circ_0067934 is an RNA molecule of 170 nucleotides located on chromosome 3q26.2. Circ_0067934 is formed via the reverse splicing of exons 15 and 16 in PRKCI (protein kinase C Iota). Recent studies revealed the upregulation or downregulation of circ_0067934 in various tumors. The expression of circ_0067934 was found to be correlated with tumor size, TNM stage, and poor prognosis. Based on experiments with cancer cells, circ_0067934 promotes cancer cell proliferation, migratory activity, and invasion when overexpressed or downregulated. The potential mechanism involves the binding of circ_0067934 to microRNAs (miRNAs; miR-545, miR-1304, miR-1301-3p, miR-1182, miR-7, and miR-1324) to regulate the post-transcriptional expression of genes. Other mechanisms include inhibition of the Wnt/β-catenin and PI3K/AKT signaling pathways. Here, we summarized the biological functions and possible mechanisms of circ_0067934 in different tumors to enable further exploration of its translational applications in clinical diagnosis, therapy, and prognostic assessments.

Depletion of circPDSS1 inhibits ITGA11 production to confer cisplatin sensitivity through miR-515-5p in gastric cancer

Chemoresistance limits cisplatin (DDP)-mediated treatment for gastric cancer (GC). Circular RNA (circRNA) acts an important role in chemoresistance. However, the underlying mechanism of circPDSS1 regulating DDP sensitivity in GC remains unclear. The expression patterns of circPDSS1, miR-515-5p and integrin subunit alpha 11 (ITGA11) were analyzed by qRT-PCR. Protein expression was checked by Western blotting analysis. Cell viability was investigated by 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell proliferation was evaluated by colony formation assay and 5-ethynyl-2'-deoxyuridine (EdU) assay. The analysis of cell apoptosis, migration and invasion was performed by flow cytometry analysis and transwell assays. Dual-luciferase reporter assay and RNA immunoprecipitation assay were conducted to identify the associations among circPDSS1, miR-515-5p and ITGA11. In vivo assay was implemented using a xenograft mouse model assay. CircPDSS1 and ITGA11 expression were significantly upregulated, whereas miR-515-5p was downregulated in DDP-resistant GC tissues and cells in comparison with controls. CircPDSS1 depletion reduced DDP resistance, cell proliferation, migration and invasion but induced cell apoptosis in DDP-resistant GC cells. CircPDSS1 directly bound to miR-515-5p. CircPDSS1-mediated actions were dependent on the regulation of miR-515-5p. Besides, miR-515-5p was associated with ITGA11, and circPDSS1 regulated ITGA11 expression by binding to miR-515-5p. Overexpression of miR-515-5p improved DDP sensitivity owing to the downregulation of ITGA11. Further, circPDSS1 mediated DDP sensitivity by regulating miR-515-5p and ITGA11 in vivo. CircPDSS1 conferred DDP resistance through the miR-515-5p/ITGA11 axis in GC cells.

EIF4A3-regulated hsa_circ_0001445 can inhibit the progression of laryngeal squamous cell carcinoma via hsa-miR-432-5p-dependent up-regulation of RGMA expression

Laryngeal squamous cell carcinoma (LSCC) is a common malignant tumor in the head and neck, the 5-year relative survival rate of patients diagnosed with laryngeal cancer was estimated to be 61% from 2012 to 2018. An increasing number of studies have shown that circular RNAs (circRNAs) play a key role in the occurrence and development of cancer and may function as cancer biomarkers and new therapeutic targets. At present, the research on the relationship between circRNAs and LSCC is still in its infancy and needs further exploration. In this study, we found a circRNA (hsa_circ_0001445) associated with LSCC based on bioinformatics analysis. Quantitative real-time polymerase chain reaction (qRT-PCR) assay indicated that the expression of hsa_circ_0001445 was down-regulated in LSCC tissues and cell lines. Notably, the expression of hsa_circ_0001445 was negatively correlated with aggressive clinicopathological features and poor prognosis. Then, functional experiments found that overexpression of hsa_circ_0001445 inhibited the proliferation, migration and invasion of LSCC cells and tumor growth in vivo. Mechanistically, RNA immunoprecipitation (RIP), biotin-labeled probe pull-down, luciferase reporter assay and western blot experiments were employed and found that EIF4A3 reduced the expression of hsa_circ_0001445, and the direct binding of hsa_circ_0001445 to hsa-miR-432-5p attenuated the inhibitory effect of hsa-miR-432-5p on RGMA. In summary, our research suggests that hsa_circ_0001445 may be used as a potential prognostic biomarker and therapeutic target for LSCC.

circRPS19 affects HK2‑mediated aerobic glycolysis and cell viability via the miR‑125a‑5p/USP7 pathway in gastric cancer

Despite advances in diagnosis and treatment, gastric cancer (GC) remains a refractory disease, which limits overall survival. Therefore, it is key to identify novel targets to develop more effective and precise treatment. Circular RNAs (circRNAs) serve essential roles in the process of various human cancers. Through analyzing GSE83521 dataset, the present study identified a novel circRNA derived from ribosomal protein S19 (circRPS19), which was considered a potential treatment target for GC. Results of RT‑qPCR indicated that circRPS19 was upregulated in GC compared with normal gastric epithelial cells. Loss‑of function assays revealed that silencing of circRPS19 suppressed proliferation and aerobic glycolysis but increased apoptosis of GC cells. circRPS19 upregulated ubiquitin‑specific processing protease 7 (USP7) expression by sponging microRNA (miR)‑125a‑5p. circRPS19 stabilized hexokinase 2 (HK2) protein by USP7‑mediated deubiquitination of HK2. In vivo experiments confirmed that circRPS19 promoted GC progression and aerobic glycolysis. Taken together, circRPS19 induced aerobic glycolysis of GC cells by stabilizing HK2 protein via the miR‑125a‑5p/USP7 axis and thus promoting the progression of GC. These findings suggested that circRPS19 served a critical role in the progression of GC and may be a novel therapeutic target for GC.

Molecular interplay between EIF4 family and circular RNAs in cancer: Mechanisms and therapeutics

The eukaryotic translation initiation factor 4 (EIF4) family is a major contributor to the recruitment of mRNAs to ribosomes during the initial translation stage in eukaryotes, whose dysregulation either allows for cancer transformation or prevents disordered cancerous cell growth. Circular RNAs (circRNAs), which exhibit distinctive structures and are widely expressed in eukaryotes, are anticipated to be a clinical diagnostic biomarker for cancer therapy. There is considerable evidence that EIF4s can influence the biogenesis, transport, and function of circRNAs and, in turn, circRNAs can control the expressions of EIF4s through certain molecular pathways. Herein, we primarily review the emerging studies of the EIF4 family and pinpoint the roles of dysregulated EIF4s in cancer. We also evaluate the patterns of intricate interactions between circRNAs and EIF4s and discuss the potential utility of circRNA-based therapeutics targeting EIF4s in clinical cancer research.

NSD2 promotes pressure overload-induced cardiac hypertrophy via activating circCmiss1/TfR1/ferroptosis signaling

Heart failure typically occurs early in the clinical course of sustained cardiac hypertrophy that is accompanied by maladaptive remodeling of the heart. It is critical to discover new mechanisms and effective therapeutic targets to prevent and cure pathological cardiac hypertrophy. The objective of the study was to evaluate the effects of circRNAs on NSD2-induced ventricular remodeling. We screened the dysregulated circRNAs in normal or NSD2^-/- C57BL/6 mice with or without transverse aortic constriction (TAC), and found that circCmss1 significantly increased in normal TAC mice, but decreased in NSD2^-/- TAC mice. Angiotensin II(Ang II)induced neonatal cardiomyocyte hypertrophy in vitro and the pressure overload-induced cardiac hypertrophy in vivo can be reduced by Knocking down circCmss1. We further investigated the downstream signaling of circCmss1 in the progression of NSD2-promoted ventricular remodeling and discovered that circCmss1 could interact with a transcription factor EIF4A3 and induce the expression of transferrin receptor 1 (TfR1), thus activating the ferroptosis in cardiomyocytes. This study highlights the significance of NSD2 activation of circCmss1/EIF4A3/TfR1 as therapeutic targets for treating pathological myocardial hypertrophy.

Non-coding RNAs and exosomal ncRNAs in multiple myeloma: An emphasis on molecular pathways

One of the most common hematological malignancies is multiple myeloma (MM) that its mortality and morbidity have increased. The incidence rate of MM is suggested to be higher in Europe and various kinds of therapeutic strategies including stem cell transplantation. However, MM treatment is still challenging and gene therapy has been shown to be promising. The non-coding RNAs (ncRNAs) including miRNAs, lncRNAs and circRNAs are considered as key players in initiation, development and progression of MM. In the present review, the role of ncRNAs in MM progression and drug resistance is highlighted to provide new insights for future experiments for their targeting and treatment of MM. The miRNAs affect proliferation and invasion of MM cells, and targeting tumor-promoting miRNAs can induce apoptosis and cell cycle arrest, and reduces proliferation of MM cells. Furthermore, miRNA regulation is of importance for modulating metastasis and chemotherapy response of tumor cells. The lncRNAs exert the same function and determine proliferation, migration and therapy response of MM cells. Notably, lncRNAs mainly target miRNAs in regulating MM progression. The circRNAs also target different molecular pathways in regulating MM malignancy that miRNAs are the most well-known ones. Furthermore, clinical application of ncRNAs in MM is discussed.

Circular RNA, circular RARS, promotes aerobic glycolysis of non-small-cell lung cancer by binding with LDHA

PURPOSE

Accumulating evidence has highlighted the critical roles of circular RNAs (circRNAs) in non-small-cell lung cancer (NSCLC). This study aims to unveil the roles of circRARS (circular RARS) (hsa_circ_0001551) in NSCLC.

METHODS

Quantitative real-time PCR was used to determine the expression of circRARS in NSCLC tissues and cells. Kaplan-Meier analysis was used to determine the prognostic value of circRARS expression. CCK8, transwell, and wound healing assays were used to assess the proliferation, invasion, and migration abilities of NSCLC cells. RNA pull-down, cell fraction, glucose consumption, lactate production, and lactate dehydrogenase activity assays were conducted to explore the potential mechanisms of circRARS in NSCLC.

RESULTS

circRARS is upregulated in NSCLC tissues and positively correlated with smoking status, lymph node metastasis, and higher tumor stages. NSCLC patients with high expression of circRARS have poor overall survival. Functional assays demonstrated that circRARS accelerated the proliferation, invasion, and migration of NSCLC cells in vitro. The cell fraction suggested that circRARS mainly accumulated in cytoplasm and the RNA pull-down assay showed lactate dehydrogenase (LDHA) could bind with circRARS. Furthermore, circRARS positively regulates LDHA activity and LDHA expression at the transcription level. Moreover, downregulated circRARS decreases glucose consumption and lactate production and compromises aerobic glycolysis in NSCLC cells. Finally, rescue assays showed circRARS could promote NSCLC cell proliferation by regulating LDHA activity.

CONCLUSION

This study shows that circRARS can promote glycolysis and tumor progression in NSCLC by regulating LDHA.

Ferroptosis-associated circular RNAs: Opportunities and challenges in the diagnosis and treatment of cancer

Ferroptosis is an emerging form of non-apoptotic regulated cell death which is different from cell death mechanisms such as autophagy, apoptosis and necrosis. It is characterized by iron-dependent lipid peroxide accumulation. Circular RNA (circRNA) is a newly studied evolutionarily conserved type of non-coding RNA with a covalent closed-loop structure. It exhibits universality, conservatism, stability and particularity. At present, the functions that have been studied and found include microRNA sponge, protein scaffold, transcription regulation, translation and production of peptides, etc. CircRNA can be used as a biomarker of tumors and is a hotspot in RNA biology research. Studies have shown that ferroptosis can participate in tumor regulation through the circRNA molecular pathway and then affect cancer progression, which may become a direction of cancer diagnosis and treatment in the future. This paper reviews the molecular biological mechanism of ferroptosis and the role of circular RNA in tumors and summarizes the circRNA related to ferroptosis in tumors, which may inspire research prospects for the precise prevention and treatment of cancer in the future.

EIF4A3 serves as a prognostic and immunosuppressive microenvironment factor and inhibits cell apoptosis in bladder cancer

EIF4A3 (Eukaryotic translation initiation factor 4A3 (EIF4A3) was recently recognized as an oncogene; however, its role in BLCA (bladder cancer) remains unclear. We explored EIF4A3 expression and its prognostic value in BLCA in public datasets, including the TCGA (The Cancer Genome Atlas) and GEO (Gene Expression Omnibus). Thereafter, the association between EIF4A3 expression and the infiltration of immune cells and immune-checkpoint expression was determined using TIMER2 (Tumor Immune Estimation Resource 2) tool. Additionally, the impact of EIF4A3 on cellular proliferation and apoptosis events in BLCA cell lines was determined by siRNA technology. In this study, EIF4A3 was found to be significantly upregulated in BLCA, upregulated expression of EIF4A3 was related to poor prognosis, advanced histologic grade, subtype, pathological stage, white race, and poor primary therapy outcome. The immune infiltration analysis revealed that EIF4A3 expression was negatively associated with CD8⁺ and CD4⁺ T cells and positively with myeloid-derived suppressor cells, macrophage M2, cancer-associated fibroblasts, and Treg cells. Moreover, EIF4A3 was coexpressed with PD-L1 (programmed cell death 1-ligand 1) and its expression was higher in patients responding to anti-PD-L1 therapy. EIF4A3 knockdown significantly inhibited proliferation and promoted apoptosis in 5,637 and T24 cells. In summary, BLCA patients with elevated EIF4A3 expression had an unfavorable prognosis and immunosuppressive microenvironment, and EIF4A3 may facilitate BLCA progression by promoting cell proliferation and inhibiting apoptosis. Furthermore, our study suggests that EIF4A3 is a potential biomarker and therapeutic target for BLCA.

A novel signature based on CeRNA and immune status predicts prognostic risk and drug sensitivity in gastric cancer patients

Background

At present, there is increasing evidence that both competitive endogenous RNAs (ceRNAs) and immune status in the tumor microenvironment (TME) can affect the progression of gastric cancer (GC), and are closely related to the prognosis of patients. However, few studies have linked the two to jointly determine the prognosis of patients with GC. This study aimed to develop a combined prognostic model based on ceRNAs and immune biomarkers.

Methods

First, the gene expression profiles and clinical information were downloaded from TCGA and GEO databases. Then two ceRNA networks were constructed on the basis of circRNA. Afterwards, the key genes were screened by univariate Cox regression analysis and Lasso regression analysis, and the ceRNA-related prognostic model was constructed by multivariate Cox regression analysis. Next, CIBERSORT and ESTIMATE algorithms were utilized to obtain the immune cell infiltration abundance and stromal/immune score in TME. Furthermore, the correlation between ceRNAs and immunity was found out through co-expression analysis, and another immune-related prognosis model was established. Finally, combining these two models, a comprehensive prognostic model was built and visualized with a nomogram.

Results

The (circRNA, lncRNA)-miRNA-mRNA regulatory network of GC was constructed. The predictive power of ceRNA-related and immune-related prognosis models was moderate. Co-expression analysis showed that the ceRNA network was correlated with immunity. The integrated model of combined ceRNAs and immunity in the TCGA training set, the AUC values of 1, 3, and 5-year survival rates were 0.78, 0.76, and 0.78, respectively; in the independent external validation set GSE62254, they were 0.81, 0.79, and 0.78 respectively; in GSE15459, they were 0.84, 0.88 and 0.89 respectively. Besides, the prognostic score of the comprehensive model can predict chemotherapeutic drug resistance. Moreover, we found that plasma variant translocation 1 (PVT1) and infiltrating immune cells (mast cells) are worthy of further investigation as independent prognostic factors.

Conclusions

Two ceRNA regulatory networks were constructed based on circRNA. At the same time, a comprehensive prognosis model was established, which has a high clinical significance for prognosis prediction and chemotherapy drug selection of GC patients.

CircRNA circ-MYBL2 absorbs precursor miR-92b in the nucleus to suppress its role in enhancing gastric cancer cell proliferation

BACKGROUND

MM-associated circular RNA (Circ-MYBL2), a circular RNA (circRNA), participates in cancer biology. However, its role in gastric cancer (GC) is unclear. In this study, circ-MYBL2 was predicted to interact with precursor microRNA-92b (miR-92b). We then analyzed the role of circ-MYBL2 in GC and explored its crosstalk with miR-92b.

METHODS

In this research Circ-MYBL2 and miR-92b (mature and precursor) accumulation was determined using reverse transcription polymerase chain reaction (RT-qPCR). The involvement of circ-MYBL2 in the maturation of miR-92b was analyzed using overexpression assays. The subcellular location of circ-MYBL2 was determined using nuclear fractionation assay. The binding of precursor miR-92b to circ-MYBL2 was analyzed through RNA-RNA pulldown assay. The role of circ-MYBL2 and miR-92b in GC cell proliferation was studied with BrdU assay.

RESULTS

We found that GC tissues exhibited increased mature miR-92b levels but decreased precursor miR-92b and circ-MYBL2 levels. Circ-MYBL2 was detected in both the nucleus and cytoplasm in GC cells, and it directly interacted with precursor miR-92b. Moreover, circ-MYBL2 overexpression increased precursor miR-92b expression and decreased mature miR-92b level. Furthermore, miR-92b (mature) increased GC cell proliferation, and circ-MYBL2 decreased GC cell proliferation and suppressed the effect of miR-92b on GC cell proliferation.

CONCLUSIONS

Circ-MYBL2 may absorb precursor miR-92b in the nucleus to suppress its role in promoting gastric cancer cell proliferation.

The landscape of circular RNA in preterm birth

Background

Preterm birth (PTB) is a multifactorial syndrome that seriously threatens the health of pregnant women and babies worldwide. Recently, circular RNAs (circRNAs) have been understood as important regulators of various physiological and pathological processes. However, the expression pattern and potential roles of circRNAs in PTB are largely unclear.

Methods

In this study, we extracted and analyzed the circRNA expression profiles in maternal and fetal samples of preterm and term pregnancies, including maternal plasma, maternal monocytes, myometrium, chorion, placenta, and cord blood. We identified the circRNAs which is associated with PTB in different tissues and explored their relationships from the perspective of the overall maternal-fetal system. Furthermore, co-expression analysis of circRNAs and mRNAs, target microRNAs (miRNAs), and RNA-binding proteins (RBPs), provided new clues about possible mechanisms of circRNA function in PTB. In the end, we investigated the potential special biofunctions of circRNAs in different tissues and their common features and communication in PTB.

Results

Significant differences in circRNA types and expression levels between preterm and term groups have been proved, as well as between tissues. Nevertheless, there were still some PTB-related differentially expressed circRNAs (DECs) shared by these tissues. The functional enrichment analysis showed that the DECs putatively have important tissue-specific biofunctions through their target miRNA and co-expressed mRNAs, which contribute to the signature pathologic changes of each tissue within the maternal-fetal system in PTB (e.g., the contraction of the myometrium). Moreover, DECs in different tissues might have some common biological activities, which are mainly the activation of immune-inflammatory processes (e.g., interleukin1/6/8/17, chemokine, TLRs, and complement).

Conclusions

In summary, our data provide a preliminary blueprint for the expression and possible roles of circRNAs in PTB, which lays the foundation for future research on the mechanisms of circRNAs in PTB.

Effect of lncRNA00511 on Non-Small Cell Lung Cancer by Regulating miR-29b-3p

This study assessed the effect of LINC00511 on NSCLC cells through regulating miR-29b-3p/DRAM1 axis. LINC00511 expression in NSCLC tissue and para-carcinoma tissue was analyzed and its correlation with TNM stage was assessed. Lung carcinoma cells as A549 cells were cultivated in vitro and transfected with LINC00511 siRNA or plasmid with DRAM1 overexpression followed by analysis of LINC00511 and miR-184 expression by RT-PCR, cell proliferation and invasion, Bcl-2, Bax and DRAM1 expression by Western Blot. LINC00511 was significantly upregulated in NSCLC tissue and positively correlated with the TNM staging. However, miR-29b-3p was significantly downregulated in NSCLC tissue. The miR-29b-3p was a target of LINC00511. The DRAM1 was a target of miR-29b-3p. Downregulation of LINC00511 restrained proliferation and invasion of A549 cells and promoted cell apoptosis. The development of NSCLC could be prompted by increasing the presentation of LINC00511 through increasing presentation of DRAM1 and being targeted with miR-29b-3p. It could be restrained through reducing the presentation of LINC00511.

Critical Roles of Circular RNA in Tumor Metastasis via Acting as a Sponge of miRNA/isomiR

Circular RNAs (circRNAs), a class of new endogenous non-coding RNAs (ncRNAs), are closely related to the carcinogenic process and play a critical role in tumor metastasis. CircRNAs can lay the foundation for tumor metastasis via promoting tumor angiogenesis, make tumor cells gain the ability of migration and invasion by regulating epithelial-mesenchymal transition (EMT), interact with immune cells, cytokines, chemokines, and other non-cellular components in the tumor microenvironment, damage the normal immune function or escape the immunosuppressive network, and further promote cell survival and metastasis. Herein, based on the characteristics and biological functions of circRNA, we elaborated on the effect of circRNA via circRNA-associated competing endogenous RNA (ceRNA) network by acting as miRNA/isomiR sponges on tumor angiogenesis, cancer cell migration and invasion, and interaction with the tumor microenvironment (TME), then explored the potential interactions across different RNAs, and finally discussed the potential clinical value and application as a promising biomarker. These results provide a theoretical basis for the further application of metastasis-related circRNAs in cancer treatment. In summary, we briefly summarize the diverse roles of a circRNA-associated ceRNA network in cancer metastasis and the potential clinical application, especially the interaction of circRNA and miRNA/isomiR, which may complicate the RNA regulatory network and which will contribute to a novel insight into circRNA in the future.

RNA-binding proteins and cancer metastasis

RNA-binding proteins (RBPs) can regulate gene expression through post-transcriptionally influencing all manner of RNA biology, including alternative splicing (AS), polyadenylation, stability, and translation of mRNAs, as well as microRNAs (miRNAs) and circular RNAs (circRNAs) processing. There is accumulating evidence reinforcing the perception that dysregulation or dysfunction of RBPs can lead to various human diseases, including cancers. RBPs influence diverse cancer-associated cellular phenotypes, such as proliferation, apoptosis, senescence, migration, invasion, and angiogenesis, contributing to the initiation and development of tumors, as well as clinical prognosis. Metastasis is the leading cause of cancer-related recurrence and death. Therefore, it is necessary to elucidate the molecular mechanisms behind tumor metastasis. In fact, a growing body of published research has proved that RBPs play pivotal roles in cancer metastasis. In this review, we will summarize the recent advances for helping us understand the role of RBPs in tumor metastasis, and discuss dysfunctions and dysregulations of RBPs affecting metastasis-associated processes including epithelial-mesenchymal transition (EMT), migration, and invasion of cancer cells. Furthermore, we will discuss emerging RBP-based strategy for the treatment of cancer metastasis.

Hsa_circ_0004296 inhibits metastasis of prostate cancer by interacting with EIF4A3 to prevent nuclear export of ETS1 mRNA

BACKGROUND

Circular RNAs (circRNAs) have been shown to play vital biological functions in various tumors, including prostate cancer (PCa). However, the roles of circRNAs in the metastasis of PCa remain unclear. In the present study, differentially expressed circRNAs associated with PCa metastasis were screened using high-throughput RNA sequencing, from which hsa_circ_0004296 was identified.

METHODS

Quantitative real-time PCR (qRT-PCR) was used to detect the expression of circ_0004296 in PCa tissues and adjacent normal tissues as well as in blood and urine. Gain and loss of function experiments were performed to investigate the function of circ_0004296 in PCa. Bioinformatics analyses, RNA pull-down assay, and mass spectrometry were conducted to identify RNA-binding proteins. RNA immunoprecipitation and RNA and protein nuclear-cytoplasmic fractionation were performed to investigate the underlying mechanism. A xenograft mouse model was used to analyze the effect of circ_0004296 on PCa growth and metastasis in vivo.

RESULTS

The expression of circ_0004296 was decreased in PCa tissues, blood, and urine, which was negatively associated with metastasis. Furthermore, gain and loss of function experiments in vitro and in vivo showed that circ_0004296 inhibited the proliferation, migration, invasion, and epithelial-mesenchymal transition of PCa cells. Mechanistically, circ_0004296 regulated host gene ETS1 expression at the post-transcriptional level. EIF4A3 was identified and confirmed as the downstream binding protein of circ_0004296. EIF4A3 expression was significantly upregulated in PCa tissues and associated with PCa metastasis. Silencing EIF4A3 suppressed PCa cell proliferation, migration, invasion, and EMT.

CONCLUSIONS

Circ_0004296 overexpression efficiently inhibited ETS1 mRNA nuclear export by promoting EIF4A3 retention in the nucleus, leading to the downregulation of ETS1 expression and suppression of PCa metastasis; thus, circ_0004296 might be a potential biomarker and therapeutic target for patients with PCa.