Circular RNA circITGA7 inhibits colorectal cancer growth and metastasis by modulating the Ras pathway and upregulating transcription of its host geneITGA7

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

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

circEgg inhibits BmCPV infection by regulating the transition between H3K9me3 and H3K9ac

Our previous study demonstrated that the expression level of circRNA circEgg, which is encoded by histone-lysine N-methyltransferase eggless (BmEgg), is responsive to Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) infection in the silkworm. However, the precise relationship between BmCPV infection and circEgg remains unclear. In this study, we observed that the expression level of circEgg in both the midguts and cultured BmN cells significantly increased after BmCPV infection, while the expression of its host gene, BmEgg, exhibited an opposite trend. Transient expression experiments revealed that circEgg acts to inhibit BmCPV infection. Additionally, Western blot analyses indicated that BmCPV infection leads to a downregulation of histone 3 lysine 9 trimethylation (H3K9me3) and an upregulation of histone 3 lysine 9 acetylation (H3K9ac). Notably, the levels of H3K9ac and H3K9me3 were found to be positively and negatively correlated with circEgg expression, respectively, suggesting that circEgg may regulate the transition between H3K9me3 and H3K9ac. Mechanistically, we discovered that circEgg inhibits BmCPV infection by enhancing the H3K9ac level through the circEgg-bmo-miR-3391-5p-histone deacetylase Rpd3 network, while simultaneously reducing the H3K9me3 level via the circEgg-encoded protein circEgg-P122. Collectively, these findings indicate that circEgg plays a crucial role in inhibiting BmCPV infection by modulating the balance between H3K9me3 and H3K9ac.

Circular RNAs in neurological conditions - computational identification, functional validation, and potential clinical applications

Non-coding RNAs (ncRNAs) have gained significant attention in recent years due to advancements in biotechnology, particularly high-throughput total RNA sequencing. These developments have led to new understandings of non-coding biology, revealing that approximately 80% of non-coding regions in the genome possesses biochemical functionality. Among ncRNAs, circular RNAs (circRNAs), first identified in 1976, have emerged as a prominent research field. CircRNAs are abundant in most human cell types, evolutionary conserved, highly stable, and formed by back-splicing events which generate covalently closed ends. Notably, circRNAs exhibit high expression levels in neural tissue and perform diverse biochemical functions, including acting as molecular sponges for microRNAs, interacting with RNA-binding proteins to regulate their availability and activity, modulating transcription and splicing, and even translating into functional peptides in some cases. Recent advancements in computational and experimental methods have enhanced our ability to identify and validate circRNAs, providing valuable insights into their biological roles. This review focuses on recent developments in circRNA research as they related to neuropsychiatric and neurodegenerative conditions. We also explore their potential applications in clinical diagnostics, therapeutics, and future research directions. CircRNAs remain a relatively underexplored area of non-coding biology, particularly in the context of neurological disorders. However, emerging evidence supports their role as critical players in the etiology and molecular mechanisms of conditions such as schizophrenia, bipolar disorder, major depressive disorder, Alzheimer's disease, and Parkinson's disease. These findings suggest that circRNAs may provide a novel framework contributing to the molecular dysfunctions underpinning these complex neurological conditions.

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

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

Circular RNAs as key regulators in cancer hallmarks: New progress and therapeutic opportunities

Circular RNAs (circRNAs) have emerged as critical regulators in cancer biology, contributing to various cancer hallmarks, including cell proliferation, apoptosis, metastasis, and drug resistance. Defined by their covalently closed loop structure, circRNAs possess unique characteristics like high stability, abundance, and tissue-specific expression. These non-coding RNAs function through mechanisms such as miRNA sponging, interactions with RNA-binding proteins (RBPs), and modulating transcription and splicing. Advances in RNA sequencing and bioinformatics tools have enabled the identification and functional annotation of circRNAs across different cancer types. Clinically, circRNAs demonstrate high specificity and sensitivity in samples, offering potential as diagnostic and prognostic biomarkers. Additionally, therapeutic strategies involving circRNA mimics, inhibitors, and delivery systems are under investigation. However, their precise mechanisms remain unclear, and more clinical evidence is needed regarding their roles in cancer hallmarks. Understanding circRNAs will pave the way for novel diagnostic and therapeutic approaches, potentially improving patient outcomes.

Role of circular RNAs in cancer therapy resistance

Over the past decade, circular RNAs (circRNAs) have gained recognition as a novel class of genetic molecules, many of which are implicated in cancer pathogenesis via different mechanisms, including drug resistance, immune escape, and radio-resistance. ExosomalcircRNAs, in particular, facilitatecommunication between tumour cells and micro-environmental cells, including immune cells, fibroblasts, and other components. Notably, micro-environmental cells can reportedly influence tumour progression and treatment resistance by releasing exosomalcircRNAs. circRNAs often exhibit tissue- and cancer-specific expression patterns, and growing evidence highlights their potential clinical relevance and utility. These molecules show strong promise as potential biomarkers and therapeutic targets for cancer diagnosis and treatment. Therefore, this review aimed to briefly discuss the latest findings on the roles and resistance mechanisms of key circRNAs in the treatment of various malignancies, including lung, breast, liver, colorectal, and gastric cancers, as well as haematological malignancies and neuroblastoma.This review will contribute to the identification of new circRNA biomarkers for the early diagnosis as well as therapeutic targets for the treatment of cancer.

Personalized medicine in colorectal cancer: a comprehensive study of precision diagnosis and treatment

Colorectal cancer is a common and fatal disease that affects many people globally. CRC is classified as the third most prevalent cancer among males and the second most frequent cancer among females worldwide. The purpose of this article is to examine how personalized medicine might be used to treat colorectal cancer. The classification of colorectal cancer based on molecular profiling, including the detection of significant gene mutations, genomic instability, and gene dysregulation, is the main topic of this discussion. Advanced technologies and biomarkers are among the detection methods that are explored, demonstrating their potential for early diagnosis and precise prognosis. In addition, the essay explores the world of treatment possibilities by providing light on FDA-approved personalized medicine solutions that provide individualized and precise interventions based on patient characteristics. This article assesses targeted treatments like cetuximab and nivolumab, looks at the therapeutic usefulness of biomarkers like microsatellite instability (MSI) and circulating tumor DNA (ctDNA), and investigates new approaches to combat resistance. Through this, our review provides a thorough overview of personalized medicine in the context of colorectal cancer, ultimately highlighting its potential to revolutionize the field and improve patient care.

Diagnosis of hepatocellular carcinoma using liquid biopsy-based biomarkers: a systematic review and network meta-analysis

Introduction

The diagnostic performance of liquid biopsy-based biomarkers for HCC was comprehensively compared in this network meta-analysis (NMA).

Methods

A thorough literature search was conducted to identify all comparative studies from January 1, 2000, to January 11, 2024. The QUADAS-2 tool was utilized to appraise the quality of studies involving diagnostic performance. R (v4.3.3) and an ANOVA model-based NMA were used to assess the diagnostic accuracy of each biomarker.

Results

This study included 82 studies comprising a total of 15,024 patients.CircRNA demonstrated significantly superior performance in distinguishing HCC from healthy populations (superiority index: 3.550 (95% CI [0.143-3])) compared to other diagnostic biomarkers for HCC. "mRNA exhibited significantly superior performance in distinguishing HCC from liver disease patients (superiority index:10.621 (95% CI [7-11])) compared to other diagnostic biomarkers for HCC. Further subgroup analysis of the top-ranking liquid biopsy-based diagnostic biomarkers revealed that hsa_circ_000224 (superiority index: 3.091 (95% CI[0.143-9]) ranked remarkably higher in distinguishing HCC from both healthy populations and liver disease patients. Subgroup analysis of mRNA demonstrated that KIAA0101 mRNA (superiority index: 2.434 (95% CI [0.2-5]) ranked remarkably higher in distinguishing HCC from healthy populations and liver disease patients, respectively.

Discussion

The results of this meta-analysis show that circRNA and mRNA are the first choice for HCC diagnosis. Subsequent analysis of circRNA and mRNA highlighted hsa_circ_000224, hsa_circ_0003998, KIAA0101 mRNA and GPC-3mRNA as the optimal diagnostic biomarkers for distinguishing HCC from healthy populations and liver disease patients, respectively. Well-structured prospective studies are crucial to comprehensively validate these findings.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/,identifier CRD42024521299.

Senescence-related circRNA circHIF-1α is associated with pancreatic cancer progression

Recently, there has been growing interest in the role of circular RNAs (circRNAs) in the progression of human cancers. Cellular senescence, a known anti-tumour mechanism, has been observed in several types of cancer. However, the regulatory interplay of circRNAs with cellular senescence in pancreatic cancer (PC) is still unknown. Therefore, we identified circHIF-1α, hsa_circ_0007976, which was downregulated in senescent cells using circRNA microarray analysis. Meanwhile, significantly upregulated expression of circHIF-1α in pancreatic cancer tissue detected by reverse transcription-polymerase chain reaction (RT-qPCR) and in situ hybridization (ISH). High circHIF-1α expression levels were found to independently predict poor survival outcomes. Subsequent treatments with DOX and H2O2 resulted in significantly lower levels of circHIF-1α. CircHIF-1α knockdown induces cellular senescence and suppresses PC proliferation in vitro experiments. The ability of circHIF-1α knockdown to suppress the progression of PC cells was further confirmed in vivo experiments. Our results showed that circHIF-1α is mainly presented in the nucleus of PC cells, also in the cytoplasm. Mechanistically, circHIF-1α inhibited senescence and accelerated the progression of PC cells through miR-375 sponging, thereby promoting HIF-1α expression levels. Nuclear circHIF-1α interacted with human antigen R protein (HUR) to increase HIF-1α expression. Thus, our results demonstrated that circHIF-1α ameliorates senescence and exacerbates growth in PC cells by increasing HIF-1α through targeting miR-375 and HUR, suggesting that targeting circHIF-1α offers a potential therapeutic candidate for PC.

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

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

RREB1 could act as an immunological and prognostic biomarker: From comprehensive analysis to osteosarcoma validation

BACKGROUND

The Ras-responsive element binding protein 1 (RREB1) is a transcription factor involved in various biological processes. Notably, RREB1 plays a role in tumor immunity by regulating tumor-related gene expression, shaping the tumor microenvironment, and modulating immune checkpoints. Given these functions, RREB1 has emerged as a potential regulatory target in tumor immunotherapy. However, a comprehensive pan-cancer analysis evaluating RREB1's prognostic value and its role in modulating the immune microenvironment remains unexplored, warranting further investigation to better understand its mechanisms across different cancer types and its implications for personalized immunotherapy.

METHODS

We analyzed RREB1 expression across 33 cancer types using RNA sequencing data from the TCGA database. RREB1 alterations were further characterized using the cBioPortal database. Clinical and pathological features, along with prognostic significance, were assessed using TCGA clinical data. The involvement of RREB1 in the tumor microenvironment was evaluated using the CIBERSORT and ESTIMATE algorithms. Relationships between RREB1 expression and tumor mutation burden (TMB), as well as microsatellite instability (MSI), were investigated using Spearman's rank correlation coefficient. GSEA was applied to explore the biological functions of RREB1. Additionally, we assessed the link between RREB1 expression and the efficacy of PD-1/PD-L1 inhibitors. Finally, a series of in vitro experiments were performed to evaluate the impact of RREB1 expression on the malignant behavior of osteosarcoma (OS) and lung cancer cell lines.

RESULTS

RREB1 was overexpressed in several cancer types and correlated with patient prognosis. RREB1 expression was strongly associated with TMB, MSI, and immune cell infiltration, including regulatory T cells, CD8+ T cells, and macrophages. Furthermore, RREB1 expression was linked to immune responses and the efficacy of immunotherapy. In vitro experiments demonstrated that knockdown of RREB1 significantly inhibited the proliferation and migration of OS cells.

CONCLUSIONS

RREB1 shows potential as a prognostic marker for certain cancers and may predict the efficacy of immunotherapy. Additionally, RREB1 expression is related to immune-related markers, suggesting its role in prognosis and predicting responses to immune microenvironment therapies in specific tumors.

A novel interaction between RNA m6A methyltransferase METTL3 and RREB1

Regulation of gene expression is achieved through the modulation of regulatory inputs both pre- and post-transcriptionally. Methyltransferase-like 3 (METTL3) is a key player in pre-mRNA processing, actively catalyzing N6-methyladenosine (m6A). Among the most enriched mRNA targets of METTL3 is the Ras Responsive Element Binding Protein 1 (RREB1), a transcription factor which functions to govern cell fate, proliferation and DNA repair. Here, we show a novel interaction between METTL3 and RREB1. Further examination of this interaction indicates that METTL3's N-terminus is the primary interacting domain. Our findings uncover a novel interacting partner of METTL3, providing further insights into METTL3's regulatory network.

The pan-cancer landscape presented ITGA7 as a prognostic determinant, tumor suppressor, and oncogene in multiple tumor types

Integrin α7 (ITGA7) is an extracellular matrix-binding protein. Integrins are the main type of cell adhesive molecules in mammals, playing a role in many biological pathways. Although various studies have shown correlations between ITGA7 and various types of cancer, a comprehensive study at a pan-cancer level has not yet been conducted. In this study, we investigated the function of ITGA7 in distinct tumor types using the multi-omics relevant information, then two CeRNA regulatory network was drawn to identify the ITGA7 hub regulatory RNAs. The results indicated that the expression of ITGA7 varies in different tumors. Overexpression of ITGA7 was correlated with a worse OS in BLCA, LGG, and UVM, and the downregulation of ITGA7 was related to a worse OS in PAAD. In addition, BLCA, and UVM showed poor PFS in association with ITGA7 overexpression, and PAAD, SARC, and THCA indicated poor PFS in correlation with ITGA7 under expression. Further analyses of ITGA7 gene alteration data showed that ITGA7 amplifications may have an impact on Kidney Chromophobe prognosis. In 20 types of tumors, ITGA7 expression was linked to cancer-associated fibroblast infiltration. ITGA7 expression was linked to cancer-associated fibroblast infiltration. ITGA7-Related Gene Enrichment Analysis indicated that ITGA7 expression-correlated and functional binding genes were enriched in homotypic cell-cell adhesion, focal adhesion, and ECM-receptor interaction. This pan-cancer study found that abnormal expression of ITGA7 was correlated with poor prognosis and metastasis in different types of tumors. Thus, the ITGA7 gene may prove to be a promising biomarker for the prognosis and complication prevention of different cancers.

Promoter hypermethylation-induced downregulation of ITGA7 promotes colorectal cancer proliferation and migration by activating the PI3K/AKT/NF-κB pathway

We previously reported that integrin alpha 7 (ITGA7) was downregulated in colorectal cancer (CRC) tissues and CRC cell lines and that the lower expression of ITGA7 in CRC tissues was correlated with distant metastasis, suggesting that ITGA7 may function as a suppressor in CRC. The present research was conducted to further investigate the role and mechanisms of ITGA7 in CRC progression. First, bisulfite modification and genomic sequencing (BSP) results showed that the methylation rate of ITGA7 promoter was higher in 10 CRC tissues than in the matched normal tissues. Additionally, 5-Aza-CdR treatment increased ITGA7 expression in CRC cells. Gain-of-function assays revealed the inhibitory role of ITGA7 in CRC cell proliferation and migration. Mechanistically, RNA sequencing, RT-qPCR, and cytoplasm and nuclear separation and rescue assays indicated that knockdown of ITGA7 activated the transcription of MMP9, SETD7, and ADAM15 by enhancing the nuclear translocation of NF-κB. Moreover, CoIP and Western blot suggested a mechanistic model in which ITGA7 binds to CKAP4 to block the interaction of CKAP4 and PI3K p85α and thereby suppress the PI3K/AKT/NF-κB pathway. Accordingly, the current study suggests that ITGA7 functions as a suppressor in CRC progression and that its expression is controlled by promoter methylation.

Back to the Origin: Mechanisms of circRNA-Directed Regulation of Host Genes in Human Disease

Circular RNAs (circRNAs) have been shown to be pivotal regulators in various human diseases by participating in gene splicing, acting as microRNA (miRNA) sponges, interacting with RNA-binding proteins (RBPs), and translating into short peptides. As the back-splicing products of pre-mRNAs, many circRNAs can modulate the expression of their host genes through transcriptional, post-transcriptional, translational, and post-translational control via interaction with other molecules. This review provides a detailed summary of these regulatory mechanisms based on the class of molecules that they interact with, which encompass DNA, mRNA, miRNA, and RBPs. The co-expression of circRNAs with their parental gene productions (including linear counterparts and proteins) provides potential diagnostic biomarkers for multiple diseases. Meanwhile, the different regulatory mechanisms by which circRNAs act on their host genes via interaction with other molecules constitute complex regulatory networks, which also provide noticeable clues for therapeutic strategies against diseases. Future research should explore whether these proven mechanisms can play a similar role in other types of disease and clarify further details about the cross-talk between circRNAs and host genes. In addition, the regulatory relationship between circRNAs and their host genes in circRNA circularization, degradation, and cellular localization should receive further attention.

Unraveling the Regulatory Role of HuR/microRNA Axis in Colorectal Cancer Tumorigenesis

Colorectal cancer (CRC) remains a significant global health burden with high incidence and mortality. MicroRNAs (miRNAs) are small non-protein coding transcripts, conserved throughout evolution, with an important role in CRC tumorigenesis, and are either upregulated or downregulated in various cancers. RNA-binding proteins (RBPs) are known as essential regulators of miRNA activity. Human antigen R (HuR) is a prominent RBP known to drive tumorigenesis with a pivotal role in CRC. In this review, we discuss the regulatory role of the HuR/miRNA axis in CRC. Interestingly, miRNAs can directly target HuR, altering its expression and activity. However, HuR can also stabilize or degrade miRNAs, forming complex feedback loops that either activate or block CRC-associated signaling pathways. Dysregulation of the HuR/miRNA axis contributes to CRC initiation and progression. Additionally, HuR-miRNA regulation by other small non-coding RNAs, circular RNA (circRNAs), or long-non-coding RNAs (lncRNAs) is also explored here. Understanding this HuR-miRNA interplay could reveal novel biomarkers with better diagnostic or prognostic accuracy.

Advanced approaches of the use of circRNAs as a replacement for cancer therapy

Cancer is a broad name for a group of diseases in which abnormal cells grow out of control and are characterized by their complexity and recurrence. Although there has been progress in cancer therapy with the entry of precision medicine and immunotherapy, cancer incidence rates have increased globally. Non-coding RNAs in the form of circular RNAs (circRNAs) play crucial roles in the pathogenesis, clinical diagnosis, and therapy of different diseases, including cancer. According to recent studies, circRNAs appear to serve as accurate indicators and therapeutic targets for cancer treatment. However, circRNAs are promising candidates for cutting-edge cancer therapy because of their distinctive circular structure, stability, and wide range of capabilities; many challenges persist that decrease the applications of circRNA-based cancer therapeutics. Here, we explore the roles of circRNAs as a replacement for cancer therapy, highlight the main challenges facing circRNA-based cancer therapies, and discuss the key strategies to overcome these challenges to improve advanced innovative therapies based on circRNAs with long-term health effects.

Advanced strategies of targeting circular RNAs as therapeutic approaches in colorectal cancer drug resistance

Colorectal cancer (CRC) stands second in terms of mortality and third among the highest prevalent kinds of cancer globally. CRC prevalence is rising in moderately and poorly developed regions and is greater in economically advanced regions. Despite breakthroughs in targeted therapy, resistance to chemotherapeutics remains a significant challenge in the long-term management of CRC. Circular RNAs (circRNAs) have been involved in growing cancer therapy resistance, particularly in CRC, according to an increasing number of studies in recent years. CircRNAs are one of the novel subclasses of non-coding RNAs, previously thought of as viroid. According to studies, circRNAs have been recommended as biological markers for therapeutic targets and diagnostic and prognostic purposes. That is particularly notable given that the expression of circRNAs has been linked to the hallmarks of CRC since they are responsible for drug resistance in CRC patients; thereby, circRNAs are significant for chemotherapy failure. Moreover, knowledge concerning circRNAs remains relatively unclear despite using all these advanced techniques. Here, in this study, we will go over the most recent published work to highlight the critical roles of circRNAs in CRC development and drug resistance and highlight the main strategies to overcome drug resistance to improve clinical outcomes.

RREB1-mediated SUMOylation enhancement promotes chemoresistance partially by transcriptionally upregulating UBC9 in colorectal cancer

Chemoresistance is a main cause of chemotherapy failure and tumor recurrence. The effects of global protein SUMOylation on chemoresistance in colorectal cancer (CRC) remains to be investigated. Herein, we have proposed that the elevated SUMO2/3-modified proteins confer 5-fluorouracil (5-FU) chemoresistance acquisition in CRC. The SUMOylation levels of global proteins in CRC cell lines were elevated compared with normal colon cell line NCM460. 5-FU treatment obviously reduced SUMOylation of global proteins in 5-FU-sensitive CRC cells including HT29, HCT116 and HCT-8. However, in 5-FU-resistant HCT-8/5-FU cells, the expression level of SUMO2/3-modified proteins was increased under 5-FU exposure in a concentration-dependent manner. 5-FU treatment combined with SUMOylation inhibitor ML-792 significantly increased the sensitivity of 5-FU-resistant cells to 5-FU and reduced colony formation numbers in HCT-8/5-FU cells. And UBC9-mediated SUMOylation elevation contributes to 5-FU resistance in HCT116 cells. Moreover, we also identified RREB1 as a regulator of SUMOylation profiling of global cellular proteins via directly binding to the promoter of UBC9. Overexpression of RREB1 promoted 5-FU resistance in CRC, which was partially abolished by treatment of inhibitor ML-792. In conclusion, RREB1-enhanced protein SUMOylation contributes to 5-FU resistance acquisition in CRC.

Unraveling the modulatory manner and function of circRNAs in the Asian honey bee larval guts

Circular RNAs (circRNAs) are a class of non-coding RNAs (ncRNAs) that can participate in biological processes such as gene expression, growth, and development. However, little has been explored about the function of circRNAs in the development of Apis cerana larval guts. By using our previously gained deep sequencing data from the guts of A. cerana worker larvae at 4-, 5-, and 6-day-old (Ac4, Ac5, and Ac6 groups), the expression pattern and regulatory role of circular RNAs (circRNAs) during the development process was comprehensively investigated, with a focus on differentially expressed circRNAs (DEcircRNAs) relevant to immunity pathways and developmental signaling pathways, followed by validation of the binding relationships among a key competing endogenous RNA (ceRNA) axis. Here, 224 (158) DEcircRNAs were detected in the Ac4 vs. Ac5 (Ac5 vs. Ac6) comparison group. It's suggested that 172 (123) parental genes of DEcircRNAs were involved in 26 (20) GO terms such as developmental process and metabolic process and 138 (136) KEGG pathways like Hippo and Wnt signaling pathways. Additionally, ceRNA network analysis indicated that 21 (11) DEcircRNAs could target seven (three) DEmiRNAs, further targeting 324 (198) DEmRNAs. These DEmRNAs can be annotated to 33 (26) GO terms and 168 (200) KEGG pathways, including 12 (16) cellular and humoral immune pathways (endocytosis, lysosome, Jak-STAT, etc.) and 10 (nine) developmental signaling pathways (Hippo, mTOR, Hedgehog, etc.). Interestingly, DEcircRNAs in these two comparison groups could target the same ace-miR-6001-y, forming complex sub-networks. The results of PCR and Sanger sequencing confirmed the back-splicing sites within four randomly selected DEcircRNAs. RT-qPCR detection of these four DEcircRNAs verified the reliability of the used transcriptome data. The results of dual-luciferase reporter assay verified the binding relationships between novel_circ_001627 and ace-miR-6001-y and between ace-miR-6001-y and apterous-like. Our data demonstrated that DEcircRNAs were likely to modulate the developmental process of the A. cerana worker larval guts via regulation of parental gene transcription and ceRNA network, and novel_circ_001627/ace-miR-6001-y/apterous-like was a potential regulatory axis in the larval gut development. Findings from this work offer a basis and a candidate ceRNA axis for illustrating the circRNA-modulated mechanisms underlying the A. cerana larval guts.

Non-coding RNAs as therapeutic targets in cancer and its clinical application

Cancer genomics has led to the discovery of numerous oncogenes and tumor suppressor genes that play critical roles in cancer development and progression. Oncogenes promote cell growth and proliferation, whereas tumor suppressor genes inhibit cell growth and division. The dysregulation of these genes can lead to the development of cancer. Recent studies have focused on non-coding RNAs (ncRNAs), including circular RNA (circRNA), long non-coding RNA (lncRNA), and microRNA (miRNA), as therapeutic targets for cancer. In this article, we discuss the oncogenes and tumor suppressor genes of ncRNAs associated with different types of cancer and their potential as therapeutic targets. Here, we highlight the mechanisms of action of these genes and their clinical applications in cancer treatment. Understanding the molecular mechanisms underlying cancer development and identifying specific therapeutic targets are essential steps towards the development of effective cancer treatments.

Identification of a basement membrane-related gene signature for predicting prognosis, immune infiltration, and drug sensitivity in colorectal cancer

Background

Colorectal cancer (CRC) is the most common malignancy affecting the gastrointestinal tract. Extensive research indicates that basement membranes (BMs) may play a crucial role in the initiation and progression of the disease.

Methods

Data on the RNA expression patterns and clinicopathological information of patients with CRC were sourced from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) databases. A BM-linked risk signature for the prediction of overall survival (OS) was formulated using univariate Cox regression and combined machine learning techniques. Survival outcomes, functional pathways, the tumor microenvironment (TME), and responses to both immunotherapy and chemotherapy within varying risk classifications were also investigated. The expression trends of the model genes were evaluated by reverse transcription polymerase chain reaction (RT-PCR) and the Human Protein Atlas (HPA) database.

Results

A nine-gene risk signature containing UNC5C, TINAG, TIMP1, SPOCK3, MMP1, AGRN, UNC5A, ADAMTS4, and ITGA7 was constructed for the prediction of outcomes in patients with CRC. The expression profiles of these candidate genes were verified using RT-PCR and the HPA database and were found to be consistent with the findings on differential gene expression in the TCGA dataset. The validity of the signature was confirmed using the GEO cohort. The patients were stratified into different risk groups according to differences in clinicopathological characteristics, TME features, enrichment functions, and drug sensitivities. Lastly, the prognostic nomogram model based on the risk score was found to be effective in identifying high-risk patients and predicting OS.

Conclusion

A basement membrane-related risk signature was constructed and found to be effective for predicting the prognosis of patients with CRC.

Circular RNAs as biomarkers and therapeutic targets for gastrointestinal cancers

Circular RNAs are a class of noncoding RNAs with covalently linked 5' and 3' ends that arise from backsplicing events. The absence of a 5' cap and a 3' poly(A) tail makes circular RNAs relatively more stable than their linear counterparts. They are evolutionary conserved and tissue-specific, and some show disease-specific expression patterns. Although their biological functions remain largely unknown, circular RNAs have been shown to play regulatory roles by acting as microRNA sponges, regulators of RNA-binding proteins, alternative splicing, and parental gene expression, and they could even encode proteins. Over the past few decades, circular RNAs have attracted wide attention in oncology owing to their implications in various tumors. Many circular RNAs have been characterized as key players in gastrointestinal cancers and influence cancer growth, progression, metastasis, and therapeutic resistance. Accumulating evidence reveals that their unique characteristics, coupled with their critical roles in tumorigenesis, make circular RNAs promising non-invasive clinical biomarkers for gastrointestinal cancers. In the present review, we summarized the biological roles of the emerging circular RNAs and their potential as biomarkers and therapeutic targets, which may help better understand their clinical significance in the management of gastrointestinal cancers.

CircGNAO1 strengthens its host gene GNAO1 expression for suppression of hepatocarcinogenesis

Background

Hepatocellular carcinoma (HCC) is one of the most prevalent primary liver carcinoma. Guanine nucleotide-binding protein, α-activating activity polypeptide O (GNAO1) was reported to be under-expressed in HCC tissues. This study aimed to investigate the GNAO1-derived circular RNA (circRNA) and its molecular mechanisms in HCC.

Methods

Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot were applied to examine RNA and protein levels. Functional experiments were performed to study HCC cell proliferation, cell cycle and cellular senescence. The interactions among circGNAO1, GNAO1 and DNA methyltransferase 1 (DNMT1) were examined by mechanism assays. The methylation level was analyzed by bisulfite sequencing PCR (BSP).

Results

CircGNAO1 is down-regulated and positively associated with GNAO1 in HCC tissues. Overexpression of circGNAO1 inhibits cell proliferation, induces cell cycle arrest and facilitates cell senescence in HCC cells. CircGNAO1 facilitates the progression of HCC via modulating GNAO1. Mechanistically, circGNAO1 enhances the transcription of GNAO1 by sequestering DNMT1, thereby up-regulating GNAO1 expression in HCC cells.

Conclusions

CircGNAO1 up-regulates its host gene GNAO1 expression for suppression of hepatocarcinogenesis.

Integrative network analysis of transcriptomics data reveals potential prognostic biomarkers for colorectal cancer

INTRODUCTION

Cross-talk among biological pathways is essential for normal biological function and plays a significant role in cancer progression. Through integrated network analysis, this study explores the significance of pathway cross-talk in colorectal cancer (CRC) development at both the pathway and gene levels.

METHODS

In this study, we integrated the gene expression data with domain knowledge to construct state-dependent pathway cross-talk networks. The significance of the genes involved in pathway cross-talk was assessed by analyzing their association with cancer hallmarks, disease-gene relation, genetic alterations, and survival analysis. We also analyzed the gene regulatory network to identify the dysregulated genes and their role in CRC progression.

RESULTS

Cross-talk was observed between immune-related pathways and pathways associated with cell communication and signaling. The PTPRC gene was identified as a mediator, facilitating interactions within the immune system and other signaling pathways. The rewired interactions of ITGA7 were identified as influential in the epithelial-mesenchymal transition in CRC. This study also highlighted the crucial link between cell communication and vascular smooth muscle contraction pathway in CRC progression. The survival analysis of identified gene clusters showed their significant prognostic value in distinguishing high-risk from low-risk CRC groups, and L1000CDS2 revealed seven potential drug molecules in CRC. Nine dysregulated genes (CTNNB1, EP300, JUN, MYC, NFKB1, RELA, SP1, STAT1, and TP53) emerge as transcription factors acting as common regulators across various pathways.

CONCLUSIONS

This study highlights the crucial role of pathway cross-talk in CRC progression and identified the potential prognostic biomarkers and potential drug molecules.

circRNA6448-14/miR-455-3p/OTUB2 axis stimulates glycolysis and stemness of esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a gastrointestinal malignancy with high incidence. This study aimed to reveal the complete circRNA-miRNA-mRNA regulatory network in ESCC and validate its function mechanism.

METHOD

Expression of OTU Domain-Containing Ubiquitin Aldehyde-Binding Protein 2 (OTUB2) in ESCC was analyzed by bioinformatics to find the binding sites between circRNA6448-14 and miR-455-3p, as well as miR-455-3p and OTUB2. The binding relationships were verified by RNA Immunoprecipitation (RIP) and dual-luciferase assay. The expressions of circRNA6448-14, miR-455-3p, and OTUB2 were detected by quantitative real-time polymerase chain reaction (qRT-PCR). MTT assay measured cell viability, and the spheroid formation assay assessed the ability of stem cell sphere formation. Western blot (WB) determined the expression of marker proteins of stem cell surface and rate-limiting enzyme of glycolysis. The Seahorse XFe96 extracellular flux analyzer measured the rate of extracellular acidification rate and cellular oxygen consumption. Corresponding assay kits assessed cellular glucose consumption, lactate production, and adenosine triphosphate (ATP) generation.

RESULTS

In ESCC, circRNA6448-14 and OTUB2 were highly expressed in contrast to miR-455-3p. Knocking down circRNA6448-14 could prevent the glycolysis and stemness of ESCC cells. Additionally, circRNA6448-14 enhanced the expression of OTUB2 by sponging miR-455-3p. Overexpression of OTUB2 or silencing miR-455-3p reversed the inhibitory effect of knockdown of circRNA6448-14 on ESCC glycolysis and stemness.

CONCLUSION

This research demonstrated that the circRNA6448-14/miR-455-3p/OTUB2 axis induced the glycolysis and stemness of ESCC cells. Our study revealed a novel function of circRNA6448-14, which may serve as a potential therapeutic target for ESCC.

Potential therapeutic strategy for cancer: Multi-dimensional cross-talk between circRNAs and parental genes

In many ways, circular RNAs (circRNAs) have been demonstrated to be crucial in the onset and advancement of cancer throughout the last ten years and have become a new focus of intense research in the field of RNAs. Accumulating studies have demonstrated that circRNAs can regulate parental gene expression via a variety of biological pathways. Furthermore, research into the complex interactions between circRNAs and their parental genes will shed light on their biological roles and open up new avenues for circRNAs' potential clinical translational uses. However, to date, multi-dimensional cross-talk between circRNAs and parental genes have not been systematically elucidated. Particularly intriguing is circRNA's exploration of tumor targeting, and potential therapeutic uses based on the parental gene regulation perspective. Here, we discuss their biogenesis, take a fresh look at the molecular mechanisms through which circRNAs control the expression of their parental genes in cancer. We further highlight We further highlight the latest circRNA clinical translational applications, including prognostic diagnostic markers, cancer vaccines, gDNA, and so on. Demonstrating the potential benefits and future applications of circRNA therapy.

MiR-485-3p/MiR-543/MiR-337-3p is Required for the Oncogenic Potential of the Hsa_circ_0007385-MEMO1 Axis in Colorectal Cancer

Circular RNAs (circRNAs) play regulatory roles in the biological processes of multiple tumors, colorectal cancer (CRC) included. Our previous study probed the impact of circ_0007385 on CRC cell malignant behaviors, while the underlying mechanism remains obscure. In this work, the potential mechanism of hsa_circ_0007385 in CRC was probed. Functional experiments were implemented for probing the function of hsa_circ_0007385 in CRC. Further analysis revealed the relation between hsa_circ_0007385 and miRNAs. A xenograft mouse model was implemented for probing the influence of hsa_circ_0007385 on CRC growth and metastasis in vivo. Hsa_circ_0007385 was up-regulated in CRC. Hsa_circ_0007385 positively regulated its host gene mediator of cell motility 1 (MEMO1). Hsa_circ_0007385 silencing inhibited CRC progression. Hsa_circ_0007385 and MEMO1 bond to miR-485-3p/miR-543/miR-337-3p, and these three miRNAs were lowly expressed in CRC, and negatively modulated by hsa_circ_0007385. Hsa_circ_0007385 functioned as an oncogene in CRC in a miR-485-3p/miR-543/miR-337-3p- or MEMO1-dependent manner. Hsa_circ_0007385 promoted CRC progression via modulating miR-485-3p/miR-543/miR-337-3p/MEMO1 axis. Thus, circ-MEMO1 might be a promising therapeutic target for CRC.

Rreb1 is a key transcription factor in Sertoli cell maturation and function and spermatogenesis in mouse

Spermatogenesis is a developmental process driven by interactions between germ cells and Sertoli cells. This process depends on appropriate gene expression, which might be regulated by transcription factors. This study focused on Rreb1, a zinc finger transcription factor, and explored its function and molecular mechanisms in spermatogenesis in a mouse model. Our results showed that RREB1 was predominantly expressed in the Sertoli cells of the testis. The decreased expression of RREB1 following injection of siRNA caused impaired Sertoli cell development, which was characterized using a defective blood-testis barrier structure and decreased expression of Sertoli cell functional maturity markers; its essential trigger might be SMAD3 destabilization. The decreased expression of RREB1 in mature Sertoli cells influenced the cell structure and function, which resulted in abnormal spermatogenesis, manifested as oligoasthenoteratozoospermia, and we believe RREB1 plays this role by regulating the transcription of Fshr and Wt1. RREB1 has been reported to activate Fshr transcription, and we demonstrated that the knockdown of Rreb1 caused a reduction in follicle-stimulating hormone receptor (FSHR) in the testis, which could be the cause of the increased sperm malformation. Furthermore, we confirmed that RREB1 directly activates Wt1 promoter activity, and RREB1 downregulation induced the decreased expression of Wt1 and its downstream polarity-associated genes Par6b and E-cadherin, which caused increased germ-cell death and reduced sperm number and motility. In conclusion, RREB1 is a key transcription factor essential for Sertoli cell development and function and is required for normal spermatogenesis.

Circular RNAs in the KRAS pathway: Emerging players in cancer progression

Circular RNAs (circRNAs) have been recognized as key components in the intricate regulatory network of the KRAS pathway across various cancers. The KRAS pathway, a central signalling cascade crucial in tumorigenesis, has gained substantial emphasis as a possible therapeutic target. CircRNAs, a subgroup of non-coding RNAs known for their closed circular arrangement, play diverse roles in gene regulation, contributing to the intricate landscape of cancer biology. This review consolidates existing knowledge on circRNAs within the framework of the KRAS pathway, emphasizing their multifaceted functions in cancer progression. Notable circRNAs, such as Circ_GLG1 and circITGA7, have been identified as pivotal regulators in colorectal cancer (CRC), influencing KRAS expression and the Ras signaling pathway. Aside from their significance in gene regulation, circRNAs contribute to immune evasion, apoptosis, and drug tolerance within KRAS-driven cancers, adding complexity to the intricate interplay. While our comprehension of circRNAs in the KRAS pathway is evolving, challenges such as the diverse landscape of KRAS mutant tumors and the necessity for synergistic combination therapies persist. Integrating cutting-edge technologies, including deep learning-based prediction methods, holds the potential for unveiling disease-associated circRNAs and identifying novel therapeutic targets. Sustained research efforts are crucial to comprehensively unravel the molecular mechanisms governing the intricate interplay between circRNAs and the KRAS pathway, offering insights that could potentially revolutionize cancer diagnostics and treatment strategies.

CircITGA7 regulates malignant phenotypes in bladder cancer cells via targeting miR-330-3p/KLF10 axis

Bladder cancer (BCa) is one of the common malignancies. Circular RNAs (circRNAs) play regulatory roles in cancer progression. CircITGA7 is a circRNA generated from several exons of ITGA7. The potential role of circITGA7 in BCa remains unknown and needs to be explored. Quantitative real time polymerase chain reaction (qRT-PCR) was used to assess circITGA7 and miR-330-3p expression in BCa tissues and cell lines. Kaplan-Meier analysis was used to evaluate the overall survival of these BCa patients. The biological function of circITGA7 was examined by overexpression of circITGA7 using CCK-8, EdU, wound-healing, and Transwell assays. Xenograft assay was performed to further validate the in vitro results. To explore the mechanism of circITGA7, luciferase reporter, RNA pull-down, fluorescence in situ hybridization (FISH) assays were employed to examine the binding interaction among circITGA7, miR-330-3p and kruppel-like factor 10 (KLF10). Western blot was used to study the protein levels of KLF10.CircITGA7 was downregulated in BCa tissues and cell lines and indicated longer overall survival. Moreover, circITGA7 restricted cell proliferation, migration and invasion of BCa through negatively regulating miR-330-3p. The in vivo model showed that circITGA7 influenced the tumor growth. Besides, the overexpression of miR-330-3p promoted cell progression by directly targeting KLF10. Mechanistically, circITGA7 inhibited BCa progression by activating KLF10 via targeting miR-330-3p.CircITGA7 alleviates BCa cell progression via circITGA7/hsa-miR-330-3p/KLF10 axis, which may provide novel therapeutic targets for BCa.

CircUSP1 as a novel marker promotes gastric cancer progression via stabilizing HuR to upregulate USP1 and Vimentin

Circular RNAs (circRNAs) play a crucial role in regulating various tumors. However, their biological functions and mechanisms in gastric cancer (GC) have not been well understood. Here, we discovered a stable cytoplasmic circRNA named circUSP1 (hsa_circ_000613) in GC. CircUSP1 upregulation in GC tissues was correlated with tumor size and differentiation. We observed that circUSP1 promoted GC growth and metastasis. Mechanistically, circUSP1 mainly interacted with the RRM1 domain of an RNA-binding protein (RBP) called HuR, stabilizing its protein level by inhibiting β-TrCP-mediated ubiquitination degradation. The oncogenic properties of HuR mediated promotive effects of circUSP1 in GC progression. Moreover, we identified USP1 and Vimentin as downstream targets of HuR in post-transcriptional regulation, mediating the effects of circUSP1. The parent gene USP1 also enhanced the viability and mobility of GC cells. Additionally, tissue-derived circUSP1 could serve as an independent prognostic factor for GC, while plasma-derived circUSP1 showed promise as a diagnostic biomarker, outperforming conventional markers including serum alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA) and carbohydrate antigen 199 (CA19-9). Our study highlights that circUSP1 promotes GC progression by binding to and stabilizing oncogenic HuR, thereby facilitating the upregulation of USP1 and Vimentin at the post-transcriptional level. These findings suggest that circUSP1 could be a potential therapeutic target and a diagnostic and prognostic biomarker for GC.

Role of circular RNAs and gut microbiome in gastrointestinal cancers and therapeutic targets

Gastrointestinal cancers are a huge worldwide health concern, which includes a wide variety of digestive tract cancers. Circular RNAs (circRNAs), a kind of non-coding RNA (ncRNAs), are a family of single-stranded, covalently closed RNAs that have become recognized as crucial gene expression regulators, having an impact on several cellular functions in cancer biology. The gut microbiome, which consists of several different bacteria, actively contributes to the regulation of host immunity, inflammation, and metabolism. CircRNAs and the gut microbiome interact significantly to greatly affect the growth of GI cancer. Several studies focus on the complex functions of circRNAs and the gut microbiota in GI cancers, including esophageal cancer, colorectal cancer, gastric cancer, hepatocellular cancer, and pancreatic cancer. It also emphasizes how changed circRNA expression profiles and gut microbiota affect pathways connected to malignancy as well as how circRNAs affect hallmarks of gastrointestinal cancers. Furthermore, circRNAs and gut microbiota have been recommended as biological markers for therapeutic targets as well as diagnostic and prognostic purposes. Targeting circRNAs and the gut microbiota for the treatment of gastrointestinal cancers is also being continued to study. Despite significant initiatives, the connection between circRNAs and the gut microbiota and the emergence of gastrointestinal cancers remains poorly understood. In this study, we will go over the most recent studies to emphasize the key roles of circRNAs and gut microbiota in gastrointestinal cancer progression and therapeutic options. In order to create effective therapies and plan for the future gastrointestinal therapy, it is important to comprehend the functions and mechanisms of circRNAs and the gut microbiota.

ADAMTS Gene-Derived circRNA Molecules in Non-Small-Cell Lung Cancer: Expression Profiling, Clinical Correlations and Survival Analysis

The present study examines the relationship between circular RNA (circRNA) derived from three genes of the family a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs): ADAMTS6, ADAMTS9 and ADAMTS12 and the host gene expression in non-small-cell lung cancer (NSCLC) with regard to various clinical factors. Notably, an association was identified between ADAMTS12 expression and specific circRNA molecules, as well as certain expression patterns of ADAMTS6 and its derived circRNA that were specific to histopathological subtypes. The survival analysis demonstrated that a lower ADAMTS6 expression in squamous cell carcinoma was associated with extended survival. Furthermore, the higher ADAMTS9 expression was linked to prolonged survival, while the overexpression of ADAMTS12 was correlated with a shorter survival. These findings suggest that circRNA molecules may serve as potential diagnostic or prognostic biomarkers for NSCLC, highlighting the importance of considering molecular patterns in distinct cancer subtypes.

Hsa_circ_0092856 Promoted the Proliferation, Migration, and Invasion of NSCLC Cells by Up-Regulating the Expression of eIF3a

Circular RNA (circRNA) plays a very important regulatory role in a variety of human malignancies such as non-small-cell lung cancer (NSCLC). In the current study, we explored the role of hsa_circ_0092856 in the progression of NSCLC. We screened CircRNA from the eIF3a gene in the Circbase database. The biological functions of hsa_circ_0092856 in NSCLC were analyzed via qRT-PCR, a CCK-8 assay, a plate cloning experiment, scratch testing, a transwell chamber experiment, an RNA nuclear mass separation experiment, an RIP experiment, and a Western blot test. The results showed that hsa_circ_0092856 was highly expressed in NSCLC cells, and the knockdown of hsa_circ_0092856 could inhibit the proliferation, migration, and invasion of NSCLC cells. The overexpression of hsa_circ_0092856 has the opposite effect. The expression of eIF3a also changed with the change in hsa_circ_0092856. These results suggest that hsa_circ_0092856 may play a key role in the progression of NSCLC by regulating the expression of eIF3a.

CircHLA-C: A significantly upregulated circRNA co-existing in oral leukoplakia and oral lichen planus

BACKGROUND

Oral leukoplakia (OLK) and oral lichen planus (OLP) are common precancerous lesions of the oral mucosa. The role of circular RNAs (circRNAs) in OLK and OLP is unclear. The aim of this study was to evaluate the circRNA expression profiles of OLK and OLP, and further explore the potential role of circRNAs in the pathogenesis of these two diseases.

METHODS

High throughput sequencing technology was performed to detect the differentially expressed circRNA in OLK (n = 6), OLP (n = 6), oral squamous cell carcinoma (n = 6), and normal oral mucosa tissues (n = 6). Expression of selected circRNAs was validated by qRT-PCR, enzyme tolerance assay, and Sanger sequencing. Expanded sample size validation was done in 20 tissue pairs. The biological processes and signal pathways involved in differential circRNA were analyzed by GO and KEGG enrichment. TargetScan and MiRanda were used to predict miRNAs downstream of circRNA and draw competitive endogenous RNA network diagram.

RESULTS

Forty-nine circRNAs were significantly altered in OLK and OLP, including 30 upregulated and 19 downregulated circRNAs. The five selected circRNAs were validated by qRT-PCR, Sanger sequencing, and RNase R assay. GO and KEGG analyses indicated that the upregulated circHLA-C may be involved in the biological process of immune function of OLK and OLP. Bioinformatics analysis indicated that circHLA-C may be involved in the progression of OLK and OLP as a ceRNA. In validation with expanded sample size, PCR results showed that circHLA-C expression was significantly upregulated in OLK and OLP. ROC analysis indicated that circHLA-C has potential diagnostic value with good accuracy and specificity.

CONCLUSION

Our study revealed that circHLA-C is the most significantly upregulated circRNA co-existing in OLK and OLP, and we preliminarily discuss the role of circHLA-C in the etiopathogenesis and progression of OLK and OLP.

Circ-SUZ12 Protects Cardiomyocytes from Hypoxia-Induced Dysfunction Through Upregulating SUZ12 Expression to Activate Wnt/β-catenin Signaling Pathway

Acute myocardial infarction (AMI) is a common coronary artery disease. This study attempted to reveal the impact of circ-SUZ12 (hsa_circ_0042961) on cardiomyocyte injury after exposure to hypoxia.Circ-SUZ12 was screened out from the GEO dataset GSE169594. RNA expression and protein level were detected by quantitative real-time PCR (qRT-PCR) and Western blot, respectively. The characteristics of circ-SUZ12 were identified by measuring its resistance to Rnase R or actinomycin D (Act D) treatment. CCK-8 and EdU assays were performed to explore the viability of AC16 cells. Cell apoptosis was assessed through TUNEL assay and flow cytometry analysis. Mechanism experiments were performed to investigate the downstream molecular mechanism of circ-SUZ12.Circ-SUZ12 was highly expressed in blood samples of AMI patients in the GEO dataset and lowly expressed in hypoxia-treated cardiomyocytes. Overexpression of circ-SUZ12 reversed hypoxia-induced cardiomyocyte injury. Circ-SUZ12 regulated SUZ12 polycomb repressive complex 2 subunit (SUZ12) expression by recruiting FUS protein. SUZ12 activated the Wnt/β-catenin signaling pathway by increasing the H3K27me3 level in microRNA (miR)-526b-5p promoter to release catenin beta 1 (CTNNB1). CTNNB1 depletion reversed the effect of circ-SUZ12 on the viability and apoptosis of hypoxia-induced cardiomyocytes.Circ-SUZ12 protects cardiomyocytes from hypoxia-induced dysfunction through upregulating SUZ12 expression to activate the Wnt/β-catenin signaling pathway.

Integrin α7β1 represses intestinal absorptive cell differentiation

Intestinal epithelial cell differentiation is a highly controlled and orderly process occurring in the crypt so that cells migrating out to cover the villi are already fully functional. Absorptive cell precursors, which originate from the stem cell population located in the lower third of the crypt, are subject to several cycles of amplification in the transit amplifying (TA) zone, before reaching the terminal differentiation compartment located in the upper third. There is a large body of evidence that absorptive cell differentiation is halted in the TA zone through various epigenetic, transcriptional and intracellular signalling events or mechanisms allowing the transient expansion of this cell population but how these mechanisms are themself regulated remains obscure. One clue can be found in the epithelial cell-matrix microenvironment located all along the crypt-villus axis. Indeed, a previous study from our group revealed that α5-subunit containing laminins such as lamimin-511 and 512 inhibit early stages of differentiation in Caco-2/15 cells. Among potential receptors for laminin 511/512 is the integrin α7β1, which has previously been reported to be expressed in the human intestinal crypts and in early stages of Caco-2/15 cell differentiation. In this study, the effects of knocking down ITGA7 in Caco-2/15 cells were studied using shRNA and CRISPR/Cas9 strategies. Abolition of the α7 integrin subunit resulted in a significant increase in the level of differentiation and polarization markers as well as the morphological features of intestinal cells. Activities of focal adhesion kinase and Src kinase were both reduced in α7-knockdown cells while the three major intestinal pro-differentiation factors CDX2, HNFα1 and HNF4α were overexpressed. Two epigenetic events associated with intestinal differentiation, the reduction of tri-methylated lysine 27 on histone H3 and the increase of acetylation of histone H4 were also observed in α7-knockdown cells. On the other hand, the ablation of α7 had no effect on cell proliferation. In conclusion, these data indicate that integrin α7β1 acts as a major repressor of absorptive cell terminal differentiation in the Caco-2/15 cell model and suggest that the laminin-α7β1 integrin interaction occurring in the transit amplifying zone of the adult intestine is involved in the transient halting of absorptive cell terminal differentiation.

Knockdown of circMFN2 inhibits cell progression and glycolysis by miR-198/CUL4B pathway in ovarian cancer

Circular RNA (circRNA) regulates malignant tumors, including ovarian cancer (OC). The present research study aimed to reveal the biological mechanism of circRNA mitofusin 2 (circMFN2) in OC. Cell biological behaviors were investigated using clonogenicity assay, EdU assay, transwell assay, and flow cytometry analysis. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis were implemented to detect the levels of circMFN2, miR-198, Cullin 4B (CUL4B), and apoptosis-related proteins. Glycolysis was assessed by glucose assay kit, lactate assay kit, and ATP level detection kit. The relationships among miR-198, circMFN2, and CUL4B were verified by dual-luciferase reporter assay and RNA immunoprecipitation assay. The xenograft mice model was used to analyze tumor growth in vivo. The expression of circMFN2 and CUL4B was increased, while miR-330-5p was decreased in OC tissues or cells. The absence of CircMFN2 hindered cell proliferation, migration, invasion, and glycolysis and promoted apoptosis in OC cells. We found that circMFN2 promoted CUL4B expression via sponging miR-198. MiR-198 depletion reversed circMFN2 knockdown-induced effects in OC cells. Furthermore, CUL4B overexpression overturned the inhibitory effect of miR-198 in OC cells. And the absence of circMFN2 inhibited tumor growth in vivo. CircMFN2 repressed OC progression by regulating the miR-198/CUL4B axis.

Functions of Circular RNA in Human Diseases and Illnesses

Circular RNAs (circRNAs) represent single-stranded RNA species that contain covalently closed 3' and 5' ends that provide them more stability than linear RNA, which has free ends. Emerging evidence indicates that circRNAs perform essential functions in many DNA viruses, including coronaviruses, Epstein-Barr viruses, cytomegalovirus, and Kaposi sarcoma viruses. Recent studies have confirmed that circRNAs are present in viruses, including DNA and RNA viruses, and play various important functions such as evading host immune response, disease pathogenesis, protein translation, miRNA sponges, regulating cell proliferation, and virus replication. Studies have confirmed that circRNAs can be biological signatures or pathological markers for autoimmune diseases, neurological diseases, and cancers. However, our understanding of circRNAs in DNA and RNA viruses is still limited, and functional evaluation of viral and host circRNAs is essential to completely understand their biological functions. In the present review, we describe the metabolism and cellular roles of circRNA, including its roles in various diseases and viral and cellular circRNA functions. Circular RNAs are found to interact with RNA, proteins, and DNA, and thus can modulate cellular processes, including translation, transcription, splicing, and other functions. Circular RNAs interfere with various signaling pathways and take part in vital functions in various biological, physiological, cellular, and pathophysiological processes. We also summarize recent evidence demonstrating cellular and viral circRNA's roles in DNA and RNA viruses in this growing field of research.

The short inverted repeats-induced circEXOC6B inhibits prostate cancer metastasis by enhancing the binding of RBMS1 and HuR

Circular RNAs (circRNAs) are a novel class of endogenous RNAs with a covalently closed loop structure. Many circRNAs have been found to participate in cancer progression. However, the detailed generation process, functions, and related mechanisms of circRNAs in prostate cancer (PCa) remain largely unknown. In the present study, we identified circEXOC6B, a novel suppressor in the metastasis of PCa. Functionally, circEXOC6B, originating from the exocyst complex component 6B (EXOC6B) gene, inhibited migration and invasion of PCa in vitro and in vivo. Mechanistically, by acting as a protein scaffold, circEXOC6B enhanced the binding of human RNA binding motif single strand interacting protein 1 (RBMS1) and human antigen R (HuR) and further increased A-kinase anchoring protein 12 (AKAP12) expression to inhibit PCa metastasis. Unlike previous studies, we found that one pair of short inverted repeats in flanking introns at least partly promoted the circularization of circEXOC6B. Our study presents a novel mechanism for the inhibitory role of circEXOC6B in PCa metastasis and provides new insight into the molecular process of circRNA generation.

Characterization of cell-type specific circular RNAs associated with colorectal cancer metastasis

Colorectal cancer (CRC) is the most common gastrointestinal malignancy and a leading cause of cancer deaths in the United States. More than half of CRC patients develop metastatic disease (mCRC) with an average 5-year survival rate of 13%. Circular RNAs (circRNAs) have recently emerged as important tumorigenesis regulators; however, their role in mCRC progression remains poorly characterized. Further, little is known about their cell-type specificity to elucidate their functions in the tumor microenvironment (TME). To address this, we performed total RNA sequencing (RNA-seq) on 30 matched normal, primary and metastatic samples from 14 mCRC patients. Additionally, five CRC cell lines were sequenced to construct a circRNA catalog in CRC. We detected 47 869 circRNAs, with 51% previously unannotated in CRC and 14% novel candidates when compared to existing circRNA databases. We identified 362 circRNAs differentially expressed in primary and/or metastatic tissues, termed circular RNAs associated with metastasis (CRAMS). We performed cell-type deconvolution using published single-cell RNA-seq datasets and applied a non-negative least squares statistical model to estimate cell-type specific circRNA expression. This predicted 667 circRNAs as exclusively expressed in a single cell type. Collectively, this serves as a valuable resource, TMECircDB (accessible at https://www.maherlab.com/tmecircdb-overview), for functional characterization of circRNAs in mCRC, specifically in the TME.

CircRNA-miRNA-VEGFA: an important pathway to regulate cancer pathogenesis

Cancers, especially malignant tumors, contribute to high global mortality rates, resulting in great economic burden to society. Many factors are associated with cancer pathogenesis, including vascular endothelial growth factor-A (VEGFA) and circular RNAs (circRNA). VEGFA is a pivotal regulator of vascular development such as angiogenesis, which is an important process in cancer development. CircRNAs have covalently closed structures, making them highly stable. CircRNAs are widely distributed and participate in many physiological and pathological processes, including modulating cancer pathogenesis. CircRNAs act as transcriptional regulators of parental genes, microRNA (miRNA)/RNA binding protein (RBP) sponges, protein templates. CircRNAs mainly function via binding to miRNAs. CircRNAs have been shown to influence different diseases such as coronary artery diseases and cancers by regulating VEGFA levels via binding to miRNAs. In this paper, we explored the origin and functional pathways of VEGFA, reviewed the current understanding of circRNA properties and action mechanisms, and summarized the role of circRNAs in regulating VEGFA during cancer pathogenesis.

Understanding the roles and regulation patterns of circRNA on its host gene in tumorigenesis and tumor progression

Circular RNAs (circRNAs) are a novel type of endogenous non-coding RNAs, which are covalently closed loop structures formed by precursor mRNAs (pre-mRNAs) through back-splicing. CircRNAs are abnormally expressed in many tumors, and play critical roles in a variety of tumors as oncogenes or tumor suppressor genes by sponging miRNAs, regulating alternative splicing and transcription, cis-regulating host genes, interacting with RNA binding proteins (RBPs) or encoding polypeptides. Among them, the regulation of circRNAs on their corresponding host genes is a critical way for circRNAs to exit their functions. Accumulating evidence suggests that circRNAs are able to regulate the expression of host genes at the transcriptional level, post-transcriptional level, translational level, post-translational level, or by encoding polypeptides. Therefore, this paper mainly summarized the roles and association of circRNAs and their corresponding host genes in tumorigenesis and tumor progression, generalized the circRNAs that function synergistically or antagonistically with their host genes, and elaborated the mechanisms of mutual regulation between circRNAs and their host genes. More importantly, this review provides specific references for revealing the potential application of circRNAs combined with their host genes in tumor diagnosis, treatment and prognosis.

Colon cancer transcriptome

Over the last four decades, methodological innovations have continuously changed transcriptome profiling. It is now feasible to sequence and quantify the transcriptional outputs of individual cells or thousands of samples using RNA sequencing (RNA-seq). These transcriptomes serve as a connection between cellular behaviors and their underlying molecular mechanisms, such as mutations. This relationship, in the context of cancer, provides a chance to unravel tumor complexity and heterogeneity and uncover novel biomarkers or treatment options. Since colon cancer is one of the most frequent malignancies, its prognosis and diagnosis seem to be critical. The transcriptome technology is developing for an earlier and more accurate diagnosis of cancer which can provide better protectivity and prognostic utility to medical teams and patients. A transcriptome is a whole set of expressed coding and non-coding RNAs in an individual or cell population. The cancer transcriptome includes RNA-based changes. The combined genome and transcriptome of a patient may provide a comprehensive picture of their cancer, and this information is beginning to affect treatment decision-making in real-time. A full assessment of the transcriptome of colon (colorectal) cancer has been assessed in this review paper based on risk factors such as age, obesity, gender, alcohol use, race, and also different stages of cancer, as well as non-coding RNAs like circRNAs, miRNAs, lncRNAs, and siRNAs. Similarly, they have been examined independently in the transcriptome study of colon cancer.

Circular RNAs in the Origin of Developmental Lung Disease: Promising Diagnostic and Therapeutic Biomarkers

Circular RNA (circRNA) is a newly discovered noncoding RNA that regulates gene transcription, binds to RNA-related proteins, and encodes protein microRNAs (miRNAs). The development of molecular biomarkers such as circRNAs holds great promise in the diagnosis and prognosis of clinical disorders. Importantly, circRNA-mediated maternal-fetus risk factors including environmental (high altitude), maternal (preeclampsia, smoking, and chorioamnionitis), placental, and fetal (preterm birth and low birth weight) factors are the early origins and likely to contribute to the occurrence and progression of developmental and pediatric cardiopulmonary disorders. Although studies of circRNAs in normal cardiopulmonary development and developmental diseases have just begun, some studies have revealed their expression patterns. Here, we provide an overview of circRNAs’ biogenesis and biological functions. Furthermore, this review aims to emphasize the importance of circRNAs in maternal-fetus risk factors. Likewise, the potential biomarker and therapeutic target of circRNAs in developmental and pediatric lung diseases are explored.

Circ_0007429/miR-637/TRIM71/Ago2 axis participates in the regulation of proliferation, migration, invasion, apoptosis, and aerobic glycolysis of HCC

CircRNAs play an important role in the progression of hepatocellular carcinoma (HCC), however, the role of circ_0007429 in HCC remains unknown. Using bioinformatics tools, we selected circ_0007429 that was most highly expressed in HCC tissues and investigated its role in HCC progression. Immunohistochemistry, plasmid transfection, real-time quantitative PCR, and western blot analysis were used to identify the relationship between circ_0007429 and its potential target, miR-637, and TRIM71. The regulatory effect of circ_0007429 on miR-637/TRIM71/Ago2 signaling and its key role in HCC progression were studied in vitro. A nude mouse xenograft model was used to examine tumor growth in vivo. Circ_0007429 and TRIM71 expression were upregulated, while miR-637 expression was downregulated in HCC tissues and cells compared with their expression in control groups. Knockdown of circ_0007429 enhanced apoptosis in HCC cells, while impeded proliferation, migration, invasion, and aerobic glycolysis, which were reversed by miR-637 inhibitor. High levels of circ_0007429 correlated with a poor survival rate of HCC patients. Additionally, circ_0007429 interfering inhibited tumor growth in vivo. TRIM71 directly bound to miR-637 and inhibited Ago2 expression. Moreover, circ_0007429 promotes aerobic glycolysis in HCC cells through the miR/TRIM71/Ago2 axis. Circ_0007429 promotes HCC progression by promoting cell proliferation, migration, invasion, and aerobic glycolysis and by inhibiting cell apoptosis through the miR/TRIM71/Ago2 axis. These results provide molecular insights into the mechanism of HCC and suggest that circ_0007429 could be a therapeutic target for HCC.

Crosstalk between circRNAs and the PI3K/AKT and/or MEK/ERK signaling pathways in digestive tract malignancy progression

Evidence indicates that circular RNAs (circRNAs) may play an important role in regulating gene expression by binding to miRNAs through miRNA response elements. circRNAs are formed by back-splicing and have a covalently closed structure. The biogenesis of circRNAs also appears to be regulated by certain cell-specific and/or gene-specific mechanisms, and thus some circRNAs are tissue specific and tumor-expression specific. Furthermore, the high stability and tissue specificity of circRNAs may be of value for early diagnosis, survival prediction and precision medicine. This review summarizes current knowledge regarding the classification and functions of circRNAs and the role of circRNAs in regulating the PI3K/AKT and/or MEK/ERK signaling pathways in digestive tract malignancy tumors.

A novel circRNA, hsa_circ_0069382, regulates gastric cancer progression

Aberrant expression of circRNAs is closely associated with the progression of gastric cancer; however, the specific mechanisms involved remain unclear. Our aim was to identify new gastric cancer biomarkers and explore the molecular mechanisms of gastric cancer progression. Therefore, we analyzed miRNA and circRNA microarrays of paired early-stage gastric cancer samples. Our study identified a new circRNA called hsa_circ_0069382, that had not been reported before and was expressed at low levels in gastric cancer tissues. Our study also included bioinformatics analyses which determined that the high expression of hsa_circ_0069382 regulated the BTG anti-proliferation factor 2 (BTG2)/ focal adhesion kinase (FAK) axis in gastric cancer lines by sponging for miR-15a-5p. Therefore, proliferation, invasion, and migration of gastric cancer is impacted. miR-15a-5p overexpression partially restored the effects of hsa_circ_0069382. This study provides potential new therapeutic options and a future direction to explore for gastric cancer treatment, and biomarkers.

Circ_0000395 Promoted CRC Progression via Elevating MYH9 Expression by Sequestering miR-432-5p

Colorectal cancer (CRC) has been listed as the fourth deadly cancer. Circular RNA hsa_circRNA_001046, also termed as hsa_circ_0000395 (circ_0000395), has been shown to be upregulated in CRC. Nevertheless, the function of circ_0000395 in CRC progression is unclear. 42 CRC patients were enrolled in the study. Detection of circ_0000395 expression in tissues and cells was executed using real-time quantitative polymerase chain reaction (RT-qPCR). Evaluation of circ_0000395 function was performed using loss-of-function experiments in vitro and in vivo. The regulatory mechanism of circ_0000395 was predicted by bioinformatics analysis and validated by dual-luciferase reporter and RIP assays. Exosomes were isolated by ultracentrifugation and validated by western blotting, TEM, and NTA. Circ_0000395 was strongly expressed in CRC samples and cell lines. Also, circ_0000395 repressed CRC growth in mouse models in vivo and induced CRC cell apoptosis, restrained CRC cell proliferation, migration, invasion, and EMT in vitro. Mechanistically, circ_0000395 sequestered miR-432-5p to regulate MYH9 expression. Furthermore, miR-432-5p knockdown reversed circ_0000395 silencing-mediated effects on CRC cell malignant phenotypes. MYH9 overexpression counteracted the inhibiting effects of miR-432-5p upregulation on CRC cell malignant phenotypes. Additionally, CRC cells derived from exosomal circ_0000395 promoted cancer cell malignant phenotypes. Our findings demonstrated that circ_0000395 sequestered miR-432-5p to elevate MYH9 expression, resulting in facilitating CRC progression, manifesting a potential therapeutic target for CRC.