circHIPK3 (hsa_circ_0000284) Promotes Proliferation, Migration and Invasion of Breast Cancer Cells via miR-326

Emerging role and clinical applications of circular RNAs in human diseases

Circular RNAs (circRNAs) are a large family of non-coding RNAs characterized by a single-stranded, covalently closed structure, predominantly synthesized through a back-splicing mechanism. While thousands of circRNAs have been identified, only a few have been functionally characterized. Although circRNAs are less abundant than other RNA types, they exhibit exceptional stability due to their covalently closed structure and demonstrate high cell and tissue specificity. CircRNAs play a critical role in maintaining cellular homeostasis by influencing gene transcription, translation, and post-translation processes, modulating the immune system, and interacting with mRNA, miRNA, and proteins. Abnormal circRNA expression has been associated with a wide range of human diseases and various infections. Due to their remarkable stability in body fluids and tissues, emerging research suggests that circRNAs could serve as diagnostic and therapeutic biomarkers for these diseases. This review focuses on the emerging role of circRNAs in various human diseases, exploring their biogenesis, molecular functions, and potential clinical applications as diagnostic and therapeutic biomarkers with current evidence, challenges, and future perspectives. The key theme highlights the significance of circRNAs in regulating gene expression, their involvement in diseases like cancer, neurodegenerative disorders, cardiovascular diseases, and diabetes, and their potential use in translational medicine for developing novel therapeutic strategies. We also discuss recent clinical trials involving circRNAs. Thus, this review is important for both basic researchers and clinical scientists, as it provides updated insights into the role of circRNAs in human diseases, aiding further exploration and advancements in the field.

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.

Circ_0000284 Is Involved in Arsenite-Induced Hepatic Insulin Resistance Through Blocking the Plasma Membrane Translocation of GLUT4 in Hepatocytes via IGF2BP2/PPAR-γ

Arsenic exposure can induce liver insulin resistance (IR) and diabetes (DM), but the underlying mechanisms are not yet clear. Circular RNAs (circRNAs) are involved in the regulation of the onset of diabetes, especially in the progression of IR. This study aimed to investigate the role of circRNAs in arsenic-induced hepatic IR and its underlying mechanism. Male C57BL/6J mice were given drinking water containing sodium arsenite (0, 0.5, 5, or 50 ppm) for 12 months. The results show that sodium arsenite increased circ_0000284 expression, decreased insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) and peroxisome proliferator-activated receptor-γ (PPAR-γ), and inhibited cell membrane protein levels of insulin-responsive glucose transporter protein 4 (GLUT4) in the mouse livers, indicating that arsenic exposure causes liver damage and disruptions to glucose metabolism. Furthermore, sodium arsenite reduced glucose consumption and glycogen levels, increased the expression of circ_0000284, reduced the protein levels of IGF2BP2 and PPAR-γ, and inhibited GLUT4 protein levels in the cell membranes of insulin-treated HepG2 cells. However, a circ_0000284 inhibitor reversed arsenic exposure-induced reductions in IGF2BP2, PPAR-γ, and GLUT4 levels in the plasma membrane. These results indicate that circ_0000284 is involved in arsenite-induced hepatic insulin resistance through blocking the plasma membrane translocation of GLUT4 in hepatocytes via IGF2BP2/PPAR-γ. This study provides a scientific basis for finding early biomarkers for the control of arsenic exposure and type 2 diabetes mellitus (T2DM), and discovering new prevention and control measures.

Hsa_circRNA_000166 accelerates breast cancer progression via the regulation of the miR-326/ELK1 and miR-330-5p/ELK1 axes

PURPOSES

To probe the expression, clinical significance, roles, and molecular mechanisms of circRNA_000166 in breast cancer (BC).

METHODS

Clinical tissue samples were gathered from 84 BC patients who underwent surgery at the Affiliated Hospital of Chengde Medical College. Clinical data were obtained from medical records and postoperative follow-up. Expression levels of circRNA_000166, miR-326, miR-330-5p, and ELK1 mRNA in BC tissues and cells were measured by qRT-PCR, and ELK1 protein levels were assessed by WB. Pearson's correlation analysis evaluated the interrelationships between these RNAs in clinical samples. Luciferase reporter assays verified the interactions between miR-326/miR-330-5p and circRNA_000166, as well as between miR-326/miR-330-5p and ELK1. Cell proliferation, migration, and apoptosis were examined using CCK-8, colony formation, transwell, and flow cytometry assays, respectively.

RESULTS

CircRNA_000166 was highly expressed in BC tissues and inversely correlated with miR-326/miR-330-5p levels but positively with ELK1 mRNA levels. ELK1 mRNA also inversely associated with miR-326/miR-330-5p levels in BC tissues. Importantly, our findings demonstrated that circRNA_000166 targets miR-326 and miR-330-5p, while ELK1 is the target of miR-326 and miR-330-5p in BC cells. CircRNA_000166 levels positively correlated with tumour size, TNM stage, histological grade, and lymph node metastasis, and negatively associated with postoperative progression-free survival (PFS) and overall survival (OS) in BC patients. CircRNA_000166 was also highly expressed in BC cells, and knockdown of circRNA_000166 reduced proliferation and migration, and increased apoptosis via miR-326/ELK1 and miR-330-5p/ELK1 pathways in vitro.

CONCLUSION

CircRNA_000166 enhances BC progression through miR-326/ELK1 and miR-330-5p/ELK1 pathways and shows potential as a biomarker for BC diagnosis and treatment.

Circular RNA HIPK3 mediates epithelial-mesenchymal transition of retinal pigment epithelial cells by sponging multiple microRNAs

Epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells plays key roles in the pathogenesis of multiple vitreoretinal diseases, leading to profound and permanent vision loss. Circular RNAs (circRNAs) are widespread and functional endogenous RNAs that could regulate gene expression in eukaryotes. The functions of circRNAs in mediating EMT has been reported in several diseases. In the current study, we investigated the role of circRNA HIPK3 (circHIPK3) in EMT process of RPE cells (RPE-EMT). circHIPK3 is one abundant circRNA generated from the second exon of HIPK3 mRNA. We found that circHIPK3 expression was significantly increased in TGF-β1-induced RPE-EMT model. Silencing of circHIPK3 attenuated TGF-β1-induced RPE-EMT process, whereas forced expression of circHIPK3 could trigger EMT in RPE cells. Mechanistically, circHIPK3 regulates RPE-EMT process via sponging multiple microRNAs (miRNAs). This study provides novel insights into the mechanism of RPE-EMT. Targeting circHIPK3 might serve as a therapeutic strategy in RPE-EMT associated vitreoretinal diseases.

Exosomal non-coding RNAs (ncRNAs) as potential biomarkers in tumor early diagnosis

Exosomes, extracellular vesicles carrying a cargo rich in various non-coding RNAs (ncRNAs), have emerged as crucial mediators of intercellular communication. Their stability, abundance, and specificity make exosomal ncRNAs promising candidates for biomarker discovery. The discovery of exosomal ncRNAs has unveiled a novel avenue for the exploration of biomarkers in tumor early diagnosis. This review consolidates current knowledge on the role of exosomal ncRNAs as potential biomarkers in the early detection of various tumors. We provide an overview of recent studies demonstrating the diagnostic potential of exosomal ncRNAs across multiple cancer types, highlighting their sensitivity, specificity, and feasibility for early detection. This review underscores the potential of exosomal ncRNAs as non-invasive biomarkers for early tumor diagnosis, paving the way for improved clinical outcomes through timely intervention and personalized management strategies.

Molecular mechanism of circHIPK3 in mitochondrial function in septic acute kidney injury

Cell senescence, glycolysis, and mitochondrial deficit jointly regulate the development of septic acute kidney injury (SAKI). This study aimed to explore the role of circular RNA HIPK3 (circHIPK3) in mitochondrial function in SAKI. The SAKI mouse model was established by Candida albicans infection, followed by Western blot assay, measurements of serum lactate, and adenosine triphosphate (ATP), 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimi-dazolylcarbocyanine iodide (JC-1) staining and flow cytometry. Human renal tubular epithelial cells were treated with lipopolysaccharide to establish the SAKI cell model, followed by cell counting kit-8 assay, tests of hexokinase activity, lactate production, oxygen consumption rate, extracellular acidification rate, ATP, and JC-1 staining, and Western blot assay. The roles of mitochondrial pyruvate carrier 1 (MPC1) were validated by kidney function tests, hematoxylin and eosin staining, periodic acid-Schiff staining, and SA-β-gal staining. circHIPK3 downregulation reduced glycolysis and mitochondrial dysfunction both in vivo and in vitro through the microRNA (miR)-148b-3p/DNMT1/3a/Klotho axis. Inhibition of miR-148b-3p or Klotho increased glycolysis and mitochondrial dysfunction. Knockdown of MPC1 increased lactate content and decreased ATP levels and MMP both in vivo and in vitro. Collectively, circHIPK3, in concert with the miR-148b-3p/DNMT1/3a/Klotho axis, increased glycolysis, and inhibited the negative regulation of lactate production by MPC1, and aggravated mitochondrial dysfunction and cell senescence in SAKI.

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.

Circular RNA expression profile identifies potential circulating biomarkers for keratoconus

Early diagnosis is important for improving the outcomes of keratoconus (KC). Stable expression and a closed-loop structure of circular RNAs (circRNAs) make them ideal for the diagnosis and treatment of diseases. However, the expression pattern and potential function of circRNAs in KC is not studied yet. Hence, this study explored the circRNA expression profile of KC corneas through transcriptome sequencing and circRNA expression profile analysis. The diagnostic potential of blood circRNAs for KC was explored by analysing the circRNAs' expression levels of fifty paired blood samples from patients with KC and normal controls. The results showed that 107 significantly upregulated and 145 significantly downregulated circRNAs (|fold change| ≥ 2.0, p-value <0.05) were identified in KC tissues. Eight top differently expressed circRNAs were further validated in more cornea samples. Among them, five circRNAs expressed in peripheral blood, and four circRNAs (circ_0006156, circ_0006117, circ_0000284 and circ_0001801) showed significant downregulation in KC patients' peripheral blood too. The blood circ_0000284 expression levels of early, moderate, and advanced KC patients both were significantly lower than the controls. The blood circ_0006117 expression levels present a positive correlation with corrected distance visual acuity values, and a negative correlation with back elevation values of KC eyes. Notably, the expression levels of these circRNAs distinguished KC patients from their healthy counterparts, with the area under the curve (AUC) of circ_0000284, circ_0001801, and circ_0006117 being 0.7306, 0.6871 and 0.6701, respectively. Further, the AUC value for five circRNAs under the logistic regression model was 0.8203, indicating that they can function as effective biomarkers for the KC diagnostics. In conclusion, the expression of circRNAs showed a relationship with KC, with four significantly differentially expressed circRNAs demonstrating potential as biomarkers for the disease.

Circular RNA and its potential diagnostic and therapeutic values in breast cancer

Breast cancer (BC) is one of the most common malignant tumors in women and still poses a significant threat to women worldwide. Recurrence of BC in situ, metastasis to distant organs, and resistance to chemotherapy are all attached to high mortality in patients with BC. Non-coding RNA (ncRNA) of the type known as "circRNA" links together from one end to another to create a covalently closed, single-stranded circular molecule. With characteristics including plurality, evolutionary conservation, stability, and particularity, they are extensively prevalent in various species and a range of human cells. CircRNAs are new and significant contributors to several kinds of disorders, including cardiovascular disease, multiple organ inflammatory responses and malignancies. Recent studies have shown that circRNAs play crucial roles in the occurrence of breast cancer by interacting with miRNAs to regulate gene expression at the transcriptional or post-transcriptional levels. CircRNAs offer the potential to be therapeutic targets for breast cancer treatment as well as prospective biomarkers for early diagnosis and prognosis of BC. Here, we are about to present an overview of the functions of circRNAs in the proliferation, invasion, migration, and resistance to medicines of breast cancer cells and serve as a promising resource for future investigations on the pathogenesis and therapeutic strategies.

Dual effects of circRNA in thyroid and breast cancer

CircRNA, the latest research hotspot in the field of RNA, is a special non-coding RNA molecule, which is unable to encode proteins and bind polyribosomes. As a regulatory molecule, circRNA participates in cancer cell generation and progression mainly through the mechanism of competitive endogenous RNA. In numerous regulated cancer organs, the thyroid and breast are both endocrine organs, and both are regulated by the hypothalamic pituitary gland axis. Thyroid cancer (TC) and breast cancer (BC) are both sexually prevalent in women and both are affected by hormones, thus they are intrinsically linked. In addition, recent epidemiological surveys have found that, early metastasis and recurrence of breast cancer remain the main cause of survival in breast cancer patients. Although at home and abroad, studies have shown that new targeted anti-tumor drugs with numerous tumor markers are gradually being used in the clinic, evidence for potential molecular mechanisms affecting its prognosis lacks clinical studies. Therefore, we search the relevant literature, and based on the latest domestic and international consensus, review the molecular mechanisms and regulation relevance of circRNA, compare the difference of the same circRNA in two tumors, to more deeply understand and lay the foundation for future clinical diagnostic, therapeutic and prognostic studies in large samples.

Circ_0000284 facilitates the growth, metastasis and glycolysis of intrahepatic cholangiocarcinoma through miR-152-3p-mediated PDK1 expression

BACKGROUND

Circular RNAs (circRNAs) are key molecules in the regulation of intrahepatic cholangiocarcinoma (ICC) progression. The purpose of this study was to analyze the function and underlying molecular mechanism of circ_0000284 in ICC.

METHODS

Quantitative real-time PCR was used to analyze the circ_0000284, microRNA (miR)-152-3p and pyruvate dehydrogenase kinase 1 (PDK1) expression. Cell proliferation, apoptosis, invasion and migration were executed by cell counting kit 8 assay, EdU assay, flow cytometry, transwell assay and wound healing assay, respectively. All protein expression levels were examined using western blot analysis. Cell glycolysis was analyzed by detecting glucose consumption, lactate production and ATP/ADP ratios. Target relationship was estimated by dual-luciferase reporter assay. The effect of circ_0000284 on ICC tumor growth in vivo was evaluated by constructing xenograft mice model.

RESULTS

We detected high expression of circ_0000284 in ICC tumor tissues and cells. Downregulated circ_0000284 inhibited ICC cell proliferation, invasion, migration, glycolysis, and accelerated apoptosis. MiR-152-3p was sponged by circ_0000284, and its inhibitor revoked the effect of circ_0000284 knockdown on ICC cell progression. PDK1 was a target of miR-152-3p, and its expression was suppressed by circ_0000284 knockdown. PDK1 overexpression reversed the inhibition effect of miR-152-3p on ICC cell growth, metastasis and glycolysis. In animal experiments, circ_0000284 downregulation also inhibited ICC tumor growth.

CONCLUSION

Circ_0000284 promoted the growth, metastasis and glycolysis of ICC by miR-152-3p/PDK1 pathway, showing that circ_0000284 was a potential therapeutic target for ICC.

Combined dandelion extract and all-trans retinoic acid induces cytotoxicity in human breast cancer cells

Breast cancer is one of the most prevalent and deadly cancers among women worldwide. Recently, natural compounds have been widely used for the treatment of breast cancer. Present study evaluated antiproliferative and anti-metastasis activities of two natural compounds of dandelion and all-trans-retinoic acid (ATRA) in human MCF-7 and MDA-MB231 breast cancer cells. We also evaluated the expression of MMP-2, MMP-9, IL-1β, p53, NM23 and KAI1 genes. Data showed a clear additive cytotoxic effect in concentrations of 40 μM ATRA with 1.5 and 4 mg/ml of dandelion extract in MCF-7 and MDA-MB231 cells, respectively. In both cell lines, compared with the untreated cells, the expression levels of MMP-9 and IL-1β were significantly decreased while p53 and KAI1 expression levels were increased. Besides, MMP-2 and NM23 had different expressions in the two studied cell lines. In conclusion, dandelion/ATRA co-treatment, in addition to having strong cytotoxic effects, has putative effects on the expression of anti-metastatic genes in both breast cancer cells.

Inverse Impact of Cancer Drugs on Circular and Linear RNAs in Breast Cancer Cell Lines

Altered expression of circular RNAs (circRNAs) has previously been investigated in breast cancer. However, little is known about the effects of drugs on their regulation and relationship with the cognate linear transcript (linRNA). We analyzed the dysregulation of both 12 cancer-related circRNAs and their linRNAs in two breast cancer cell lines undergoing various treatments. We selected 14 well-known anticancer agents affecting different cellular pathways and examined their impact. Upon drug exposure circRNA/linRNA expression ratios increased, as a result of the downregulation of linRNA and upregulation of circRNA within the same gene. In this study, we highlighted the relevance of identifying the drug-regulated circ/linRNAs according to their oncogenic or anticancer role. Interestingly, VRK1 and MAN1A2 were increased by several drugs in both cell lines. However, they display opposite effects, circ/linVRK1 favors apoptosis whereas circ/linMAN1A2 stimulates cell migration, and only XL765 did not alter the ratio of other dangerous circ/linRNAs in MCF-7. In MDA-MB-231 cells, AMG511 and GSK1070916 decreased circGFRA1, as a good response to drugs. Furthermore, some circRNAs might be associated with specific mutated pathways, such as the PI3K/AKT in MCF-7 cells with circ/linHIPK3 correlating to cancer progression and drug-resistance, or NHEJ DNA repair pathway in TP-53 mutated MDA-MB-231 cells.

Circular RNAs: New layer of complexity evading breast cancer heterogeneity

Advances in high-throughput sequencing techniques and bioinformatic analysis have refuted the "junk" RNA hypothesis that was claimed against non-coding RNAs (ncRNAs). Circular RNAs (circRNAs); a class of single-stranded covalently closed loop RNA molecules have recently emerged as stable epigenetic regulators. Although the exact regulatory role of circRNAs is still to be clarified, it has been proven that circRNAs could exert their functions by interacting with other ncRNAs or proteins in their own physiologically authentic environment, regulating multiple cellular signaling pathways and other classes of ncRNAs. CircRNAs have also been reported to exhibit a tissue-specific expression and have been associated with the malignant transformation process of several hematological and solid malignancies. Along this line of reasoning, this review aims to highlight the importance of circRNAs in Breast Cancer (BC), which is ranked as the most prevalent malignancy among females. Notwithstanding the substantial efforts to develop a suitable anticancer therapeutic regimen against the heterogenous BC, inter- and intra-tumoral heterogeneity have resulted in an arduous challenge for drug development research, which in turn necessitates the investigation of other markers to be therapeutically targeted. Herein, the potential of circRNAs as possible diagnostic and prognostic biomarkers have been highlighted together with their possible application as novel therapeutic targets.

Circ_0000284 upregulates RHPN2 to facilitate pancreatic cancer proliferation, metastasis, and angiogenesis through sponging miR-1179

BACKGROUND

Circular RNA (circRNA) has been confirmed to be a key regulator for pancreatic cancer (PC) progression, but the role of circ_0000284 in PC development remains unclear.

METHODS

Quantitative real-time PCR was used to measure the expression of circ_0000284, microRNA (miR)-1179, and rhophilin 2 (RHPN2). PC cell proliferation, metastasis, angiogenesis, and apoptosis were assessed by EdU assay, transwell assay, tube formation assay, and flow cytometry. Relative protein expression was determined by western blot analysis. The interaction between miR-1179 and circ_0000284 or RHPN2 was confirmed by dual-luciferase reporter assay and RNA pull-down assay.

RESULTS

Circ_0000284 was significantly upregulated in PC tissues and cells, and its knockdown inhibited PC cell proliferation, migration, invasion, and angiogenesis while promoting apoptosis. MiR-1179 was downregulated in PC tissues and cells, and it could be sponged by circ_0000284. Moreover, the miR-1179 inhibitor reversed the regulation of circ_0000284 knockdown on PC cell progression. The highly expressed RHPN2 was found in PC tissues and cells, and it could be targeted by miR-1179. Also, circ_0000284 sponged miR-1179 to regulate RHPN2 expression. Overexpressed RHPN2 could reverse the regulation of circ_0000284 knockdown on PC cell progression. In addition, interference of circ_0000284 was discovered to repress PC tumor growth by regulating miR-1179/RHPN2.RHPN2.

CONCLUSION

To sum up, our data confirmed that circ_0000284 facilitated PC malignant progression depending on the regulation of miR-1179/RHPN2 axis, suggesting that circ_0000284 might be a potential target for PC treatment.

Circular RNA_HIPK3-Targeting miR-93-5p Regulates KLF9 Expression Level to Control Acute Kidney Injury

Acute kidney injury (AKI) is a clinical syndrome caused by various reasons that results in the rapid decline of renal function in a short period of time. Severe AKI can lead to multiple organ dysfunction syndrome. Circular RNA HIPK3 (circHIPK3) derived from the HIPK3 gene is involved in multiple inflammatory processes. The present research was performed to explore the function of circHIPK3 on AKI. The AKI model was established by ischemia/reperfusion (I/R) in C57BL/6 mice or hypoxia/reoxygenation (H/R) in HK-2 cells. The function and mechanism of circHIPK3 on AKI were explored via biochemical index measurement; hematoxylin and eosin (HE) staining; 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT); flow cytometry; enzyme-linked immunosorbent assay (ELISA); western blot; quantitative real-time polymerase chain reaction (RT-qPCR); detection of reactive oxygen species (ROS) and adenosine triphosphate (ATP); and luciferase reporter assays. circHIPK3 was upregulated in kidney tissues of I/R-induced mice and in H/R-treated HK-2 cells, while the microRNA- (miR-) 93-5p level was decreased in H/R-stimulated HK-2 cells. Furthermore, circHIPK3 silencing or miR-93-5p overexpression could reduce the level of proinflammatory factors and oxidative stress and recover the cell viability in H/R-stimulated HK-2 cells. Meanwhile, the luciferase assay showed that Krüppel-like transcription factor 9 (KLF9) was the downstream target of miR-93-5p. Forced expression of KLF9 blocked the function of miR-93-5p on H/R-treated HK-2 cells. Knockdown of circHIPK3 improved the renal function and reduced the apoptosis level in vivo. In conclusion, circHIPK3 knockdown alleviated oxidative stress and apoptosis and inhibited inflammation in AKI via miR-93-5p-mediated downregulation of the KLF9 signal pathway.

Understanding the Dual Roles of CircHIPK3 in Tumorigenesis and Tumor Progression

CircHIPK3 is a type of endogenous circular RNA, which contains a covalently closed circular structure and cannot encode protein or polypeptide. CircHIPK3 is unusually expressed in varieties of tumors and plays dual roles of tumor promotion or tumor inhibition in tumorigenesis and development of tumors by serving as the sponge for miRNA in multiple tumors. Here, we reviewed the differential expression, the dual functions, the regulation mechanism, and the network in a variety of tumors as well as the potential value for the diagnosis and treatment of tumors, which are of great significance for our comprehensive understanding of the roles and mechanisms of circHIPK3 in tumors.

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.

Emerging roles of circular RNAs in neuropathic pain

Neuropathic pain is a major type of chronic pain caused by the disease or injury of the somatosensory nervous system. It afflicts about 10% of the general population with a significant proportion of patients’ refractory to conventional medical treatment. This highlights the importance of a better understanding of the molecular pathogenesis of neuropathic pain so as to drive the development of novel mechanism‐driven therapy. Circular RNAs (circRNAs) are a type of non‐coding, regulatory RNAs that exhibit tissue‐ and disease‐specific expression. An increasing number of studies reported that circRNAs may play pivotal roles in the development of neuropathic pain. In this review, we first summarize circRNA expression profiling studies on neuropathic pain. We also highlight the molecular mechanisms of specific circRNAs (circHIPK3, circAnks1a, ciRS‐7, cZRANB1, circZNF609 and circ_0005075) that play key functional roles in the pathogenesis of neuropathic pain and discuss their potential diagnostic, prognostic, and therapeutic utilization in the clinical management of neuropathic pain.