Circ-HIPK3 regulates YAP1 expression by sponging miR-381-3p to promote oral squamous cell carcinoma development

MicroRNA-mediated Krüppel-like factor 4 upregulation induces alternatively activated macrophage-associated marker and chemokine transcription in 4,4'-methylene diphenyl diisocyanate exposed macrophages

1. Occupational exposure to 4,4'-methylene diphenyl diisocyanate (MDI) is associated with occupational asthma (OA) development. Alveolar macrophage-induced recruitment of immune cells to the lung microenvironment plays an important role during asthma pathogenesis. Previous studies identified that MDI/MDI-glutathione (GSH)-exposure downregulates endogenous hsa-miR-206-3p/hsa-miR-381-3p. Our prior report shows that alternatively activated (M2) macrophage-associated markers/chemokines are induced by MDI/MDI-GSH-mediated Krüppel-Like Factor 4 (KLF4) upregulation in macrophages and stimulates immune cell chemotaxis. However, the underlying molecular mechanism(s) by which MDI/MDI-GSH upregulates KLF4 remain unclear.

2. Following MDI-GSH exposure, microRNA(miR)-inhibitors/mimics or plasmid transfection, endogenous hsa-miR-206-3p/hsa-miR-381-3p, KLF4, or M2 macrophage-associated markers (CD206, TGM2), and chemokines (CCL17, CCL22, CCL24) were measured by either RT-qPCR, western blot, or luciferase assay.

3. MDI-GSH exposure downregulates hsa-miR-206-3p/hsa-miR-381-3p by 1.46- to 9.75-fold whereas upregulates KLF4 by 1.68- to 1.99-fold, respectively. In silico analysis predicts binding between hsa-miR-206-3p/hsa-miR-381-3p and KLF4. Gain- and loss-of-function, luciferase reporter assays and RNA-induced silencing complex-immunoprecipitation (RISC-IP) studies confirm the posttranscriptional regulatory roles of hsa-miR-206-3p/hsa-miR-381-3p and KLF4 in macrophages. Furthermore, hsa-miR-206-3p/hsa-miR-381-3p regulate the expression of M2 macrophage-associated markers and chemokines via KLF4.

4. In conclusion, hsa-miR-206-3p/hsa-miR-381-3p play a major role in regulation of MDI/MDI-GSH-induced M2 macrophage-associated markers and chemokines by targeting the KLF4 transcript, and KLF4-mediated regulation in macrophages.

Bibliometric Analysis of Global Research on Circular RNA: Current Status and Future Directions

Circular RNAs (circRNAs) have gained significant attention in recent years. This bibliometric analysis aimed to provide insights into the current state and future trends of global circRNA research. The scientific output on circRNAs from 2010 to 2022 was retrieved from the Web of Science Core Collection with circRNA-related terms as the subjects. Key bibliometric indicators were calculated and evaluated using CiteSpace. A total of 7385 studies on circRNAs were identified. The output and citation number have increased rapidly after 2015. China, the USA, and Germany were top three publishing countries. Currently, circCDR1as, circHIPK3, circPVT1, circSHPRH, and circZNF609 are the most studied circRNAs; and all are related to cancer. The theme of research have shifted from transcript, exon circularization and miRNA sponge topics to the transcriptome, tumor suppressor, and biomarkers, indicating that research interests have evolved from basic to applied research. CircRNAs will continue to be a highly active research area in the near future. From the current understanding of circRNA characterization and regulatory mechanisms as miRNA sponges in cancer, future directions may examine potential diagnostic and therapeutic roles of circRNAs in cancers or the function and mechanism of circRNAs in other diseases.

The potential of circHIPK3 as a biomarker in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by leukocytosis and left shift. The primary molecular alteration is the BCR::ABL1, chimeric oncoprotein with tyrosine kinase activity, responsible for the initial oncogenesis of the disease. Therapy of CML was revolutionized with the advent of tyrosine kinase inhibitors, but it is still not considered curative and may present resistance and serious adverse effects. Discoveries in CML inaugurated a new era in cancer treatment and despite all the advances, a new biomarker is needed to detect resistance and adverse effects. Circular RNAs (circRNAs) are a special type of non-coding RNA formed through a process called backsplicing. The majority of circRNAs are derived from protein-coding genes. CircHIPK3 is formed from the second exon of the HIPK3 gene and has been found in various pathologies, including different types of cancer. New approaches have demonstrated the potential of circular RNAs in cancer research, and circHIPK3 has shown promising results. It is often associated with cellular regulatory pathways, suggesting an important role in the molecular dynamics of tumors. The identification of biomarkers is an important tool for therapeutic improvement; thus we review the role of circHIPK3 and its potential as a biomarker in CML.

The dual roles of circRNAs in Wnt/β-Catenin signaling and cancer progression

Cancer, a complex pathophysiological condition, arises from the abnormal proliferation and survival of cells due to genetic mutations. Dysregulation of cell cycle control, apoptosis, and genomic stability contribute to uncontrolled growth and metastasis. Tumor heterogeneity, microenvironmental influences, and immune evasion further complicate cancer dynamics. The intricate interplay between circular RNAs (circRNAs) and the Wnt/β-Catenin signalling pathway has emerged as a pivotal axis in the landscape of cancer biology. The Wnt/β-Catenin pathway, a critical regulator of cell fate and proliferation, is frequently dysregulated in various cancers. CircRNAs, a class of non-coding RNAs with closed-loop structures, have garnered increasing attention for their diverse regulatory functions. This review systematically explores the intricate crosstalk between circRNAs and the Wnt/β-Catenin pathway, shedding light on their collective impact on cancer initiation and progression. The review explores the diverse mechanisms through which circRNAs modulate the Wnt/β-Catenin pathway, including sponging microRNAs, interacting with RNA-binding proteins, and influencing the expression of key components in the pathway. Furthermore, the review highlights specific circRNAs implicated in various cancer types, elucidating their roles as either oncogenic or tumour-suppressive players in the context of Wnt/β-Catenin signaling. The intricate regulatory networks formed by circRNAs in conjunction with the Wnt/β-Catenin pathway are discussed, providing insights into potential therapeutic targets and diagnostic biomarkers. This comprehensive review delves into the multifaceted roles of circRNAs in orchestrating tumorigenesis through their regulatory influence on the Wnt/β-Catenin pathway.

CircRNAs: A Promising Star for Treatment and Prognosis in Oral Squamous Cell Carcinoma

CircRNAs are a class of endogenous long non-coding RNAs with a single-stranded circular structure. Most circRNAs are relatively stable, highly conserved, and specifically expressed in tissue during the cell and developmental stages. Many circRNAs have been discovered in OSCC. OSCC is one of the most severe and frequent forms of head and neck cancer today, with a poor prognosis and low overall survival rate. Due to its prevalence, OSCC is a global health concern, characterized by genetic and epigenomic changes. However, the mechanism remains vague. With the advancement of biotechnology, a large number of circRNAs have been discovered in mammalian cells. CircRNAs are dysregulated in OSCC tissues and thus associated with the clinicopathological characteristics and prognosis of OSCC patients. Research studies have demonstrated that circRNAs can serve as biomarkers for OSCC diagnosis and treatment. Here, we summarized the properties, functions, and biogenesis of circRNAs, focusing on the progress of current research on circRNAs in OSCC.

A snapshot of miRNAs in oral squamous cell carcinoma: Difference between cancer cells and corresponding normal cells

Oral squamous cell carcinoma (OSCC) constitutes the most aggressive tumors of the oral cavity and is one of the leading causes of cancer mortality worldwide. Although recent clinical treatment strategies have improved the survival rate, the outcome of OSCC patients still remains dismal because of the lack of efficient diagnostic and treatment tools. As one of the main actors of OSCC scenario, microRNAs (miRNAs) are involved in triggering, progression and metastasis through the regulation of various cancer-related signaling pathways. Identification followed by precise study of the biology and mechanism of action of miRNAs will greatly help to provide valuable insights regarding OSCC development and can be considered as an anti-OSCC target. In the current review, we have provided a focused summary of the latest published papers on the role of miRNAs in apoptosis, cell cycle, proliferation, EMT and metastasis of OSCC as well as the role of long noncoding RNAs in the modulation of miRNAs in OSCC.

Knockdown of circGOLPH3 inhibits cell progression and glycolysis by targeting miR-145-5p/lysine demethylase 2A (KDM2A) axis in oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is one of the most common head and neck malignancies. The aim of this study is to explore the role of circRNA Golgi phosphoprotein 3 (GOLPH3) (circGOLPH3) in OSCC.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were performed to detect changes in the levels of circGOLPH3, microRNA-145-5p (miR-145-5p), and lysine demethylase 2A (KDM2A). The functions of circGOLPH3 were assessed using in vitro and in vivo assays. Dual-luciferase reporter assay detected the interaction of miR-145-5p with circGOLPH3 or KDM2A.

RESULTS

circGOLPH3 expression was upregulated in OSCC. circGOLPH3 downregulation inhibited cell growth, metastasis, and glycolysis in vitro, and in vivo experiments revealed that circGOLPH3 inhibited tumor growth. In addition, circGOLPH3 bound to miR-145-5p and competitively inhibited KDM2A expression, thereby regulating OSCC cell behaviors as well as glycolysis.

CONCLUSION

circGOLPH3 exerted pro-oncogenic effects through the miR-145-5p/KDM2A axis to regulate OSCC cell behaviors.

The Diagnostic and Therapeutic Role of Circular RNA HIPK3 in Human Diseases

Circular RNAs (circRNAs) are a class of noncoding RNAs with closed-loop of single-stranded RNA structure. Although most of the circRNAs do not directly encode proteins, emerging evidence suggests that circRNAs play a pivotal and complex role in multiple biological processes by regulating gene expression. As one of the most popular circRNAs, circular homeodomain-interacting protein kinase 3 (circHIPK3) has frequently gained the interest of researchers in recent years. Accumulating studies have demonstrated the significant impacts on the occurrence and development of multiple human diseases including cancers, cardiovascular diseases, diabetes mellitus, inflammatory diseases, and others. The present review aims to provide a detailed description of the functions of circHIPK3 and comprehensively overview the diagnostic and therapeutic value of circHIPK3 in these certain diseases.

Circular RNAs play roles in regulatory networks of cell signaling pathways in human cancers

AIMS

Circular RNAs (circRNAs) are endogenous covalently closed non-coding RNAs produced by reverse splicing of linear RNA. These molecules are highly expressed in mammalian cells and show cell/tissue-specific expression patterns. They are also significantly dysregulated in various cancers and function as oncogenes or tumor suppressors. Emerging evidence reveals that circRNAs contribute to cancer progression via modulating different cell signaling pathways. Nevertheless, the functional significance of circRNAs in cell signaling pathways regulation is still largely elusive. Considering this, shedding light on the multi-pathway effects of circRNAs may improve our understanding of targeted cancer therapy. Here, we discuss how circRNAs regulate the major cell signaling pathways in human cancers.

MATERIALS AND METHODS

We adopted a systematic search in PubMed using the following MeSH terms: circRNAs, non-coding RNAs, lncRNAs, exosomal circRNAs, cancer, and cell signaling.

KEY FINDINGS

We discussed different roles of circRNAs during tumorigenesis in which circRNAs affect tumor development through activating or inactivating certain cell signaling pathways via molecular interactions using various signaling pathways. We also discussed how crosstalk between circRNAs and lncRNAs modulate tumorigenesis and provides a resource for the identification of cancer therapeutic targets.

SIGNIFICANCE

We here elucidated how circRNAs can modulate different cell signaling pathways and play roles in cancer. This can broaden our horizons toward introducing promising prognostic, diagnostic, and therapeutic targets.

RNA editing enzyme ADAR1 controls miR-381-3p-mediated expression of multidrug resistance protein MRP4 via regulation of circRNA in human renal cells

Multidrug resistance–associated protein 4 (MRP4), a member of the C subfamily of ATP-binding cassette transporters, is highly expressed in the kidneys of mammals and is responsible for renal elimination of numerous drugs. Adenosine deaminase acting on RNA 1 (ADAR1) has been reported to regulate gene expression by catalyzing adenosine-to-inosine RNA editing reactions; however, potential roles of ADAR1 in the regulation of MRP4 expression have not been investigated. In this study, we found that downregulation of ADAR1 increased the expression of MRP4 in human renal cells at the posttranscriptional level. Luciferase reporter assays and microarray analysis revealed that downregulation of ADAR1 reduced the levels of microRNA miR-381-3p, which led to the corresponding upregulation of MPR4 expression. Circular RNAs (circRNAs) are a type of closed-loop endogenous noncoding RNAs that play an essential role in gene expression by acting as miRNA sponges. We demonstrate that ADAR1 repressed the biogenesis of circRNA circHIPK3 through its adenosine-to-inosine RNA editing activity, which altered the secondary structure of the precursor of circHIPK3. Furthermore, in silico analysis suggested that circHIPK3 acts as a sponge of miR-381-3p. Indeed, we found overexpression of circHIPK3 induced the expression of MRP4 through its interference with miR-381-3p. Taken together, our study provides novel insights into regulation of the expression of xenobiotic transporters through circRNA expression by the RNA editing enzyme ADAR1.

Snail Promotes Cancer Cell Proliferation via Its Interaction with the BIRC3

Snail is implicated in tumour growth and metastasis and is up-regulated in various human tumours. Although the role of Snails in epithelial-mesenchymal transition, which is particularly important in cancer metastasis, is well known, how they regulate tumour growth is poorly described. In this study, the possible molecular mechanisms of Snail in tumour growth were explored. Baculoviral inhibitor of apoptosis protein (IAP) repeat-containing protein 3 (BIRC3), a co-activator of cell proliferation during tumourigenesis, was identified as a Snail-binding protein via a yeast two-hybrid system. Since BIRC3 is important for cell survival, the effect of BIRC3 binding partner Snail on cell survival was investigated in ovarian cancer cell lines. Results revealed that Bax expression was activated, while the expression levels of anti-apoptotic proteins were markedly decreased by small interfering RNA (siRNA) specific for Snail (siSnail). siSnail, the binding partner of siBIRC3, activated the tumour suppressor function of p53 by promoting p53 protein stability. Conversely, BIRC3 could interact with Snail, for this reason, the possibility of BIRC3 involvement in EMT was investigated. BIRC3 overexpression resulted in a decreased expression of the epithelial marker and an increased expression of the mesenchymal markers. siSnail or siBIRC3 reduced the mRNA levels of matrix metalloproteinase (MMP)-2 and MMP-9. These results provide evidence that Snail promotes cell proliferation by interacting with BIRC3 and that BIRC3 might be involved in EMT via binding to Snail in ovarian cancer cells. Therefore, our results suggested the novel relevance of BIRC3, the binding partner of Snail, in ovarian cancer development.

Serum hsa_circ_0087776 as a new oncologic marker for the joint diagnosis of multiple myeloma

Multiple myeloma (MM) is a hematologic malignancy caused by abnormal proliferation of bone marrow plasma cells, which lacks diagnostic markers and has a general prognosis. At present, the understanding of its pathogenesis provides the basis for the combined diagnosis and new targeted therapy of the disease. In this study, quantitative real-time PCR was used to detect 136 MM patients and 74 healthy controls, and the clinical application value of hsa_circ_0087776 as a new tumor marker and combined diagnosis was evaluated. The results showed that the expression of hsa_circ_0087776 was significantly lower in serum of MM patients (P-value < 0.0001), and the expression was consistent in MM cells. In the analysis of clinicopathological parameters, it was found that there were significant statistical differences with MM stage and renal injury. In addition, it significantly increased the sensitivity with ALB, β₂-MG joint diagnosis, to provide a basis for diagnosis, improve the prognosis of the disease, improve the survival of patients and quality of life. These studies suggest that hsa_circ_0087776 can be used as a new oncology marker for the combined diagnosis of MM.

Impact statement: Various evidences have shown that the role of circRNA in the occurrence and development of diseases is potentially unknown and untapped. Therefore, it has a broad prospect to find circRNA specifically expressed in MM patients for combined diagnosis and targeted therapy of MM. However, MM lacks such specific tumor markers. Therefore, the discovery of new specific tumor markers for combined diagnosis is an important milestone in the development of medical history. In the research, we founded hsa_circ_0087776 can be used as a new oncology marker for combined diagnosis of MM.

Biogenesis, cellular effects, and biomarker value of circHIPK3

Competing endogenous RNAs (ceRNAs) can indirectly regulate gene expression by competitively binding to microRNA(miRNA) through miRNA response elements (MREs) to affect miRNA-induced gene regulation, which is of great biological significance. Among them, circular RNA (circRNA) has become a hotspot due to its highest binding capacity. A specific circRNA discussed in this review, circHIPK3, has been studied for its biological characteristics, function, cellular effects and its relationship with tumors and various diseases. Here, we review the recent researches about circHIPK3 in detail and aim to elucidate accurate conclusions from them. These circHIPK3-miRNAs-mRNA pathways will further advance the application of circHIPK3 in diseases development, early diagnosis and gene targeting therapy.