circ_NRIP1 is oncogenic in malignant development of esophageal squamous cell carcinoma (ESCC) via miR-595/SEMA4D axis and PI3K/AKT pathway

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.

Circ_0004771 regulates malignant biological behaviors and has clinical significance in oral squamous cell carcinoma

BACKGROUND

The incidence of oral squamous cell carcinoma (OSCC) is increasing, and more effective treatment protocols must rapidly be developed to prevent the death of patients and ensure favorable outcomes. CircRNAs are a unique class of noncoding ribonucleic acid (RNA) molecules unaffected by RNA exonucleases. CircRNAs have more stable expression than linear RNAs and are not readily degraded; therefore, they are the newest focus of RNA research. Here, we analyze the mechanism of hsa_circ_0004771 (circ_0004771) in OSCC to provide a clinical reference.

METHODS

Circ_0004771 expression was measured in peripheral blood, cancerous tissues and adjacent tissues of OSCC patients. Patients were followed up for 3 years. The diagnostic value of circ_0004771 for OSCC occurrence, prognosis, recurrence and survival was analyzed with receiver operating characteristic (ROC) curves. OSCC cells were lentivirally transduced with a circ_0004771-silencing or an empty vector to evaluate alterations in cell growth, invasion, and apoptosis. Apoptosis-related and epithelial-mesenchymal transition (EMT)-related protein expression was quantified. BALB/c nude mice were used for tumorigenesis experiments to evaluate tumor growth in vivo after silencing circ_0004771.

RESULTS

Circ_0004771 expression was higher in peripheral blood and cancerous tissue of OSCC patients than in control peripheral blood and paracancerous tissue, respectively, exhibiting excellent predictive value for OSCC occurrence, prognosis, recurrence and survival. Silencing circ_0004771 decreased the growth, invasiveness, and EMT capacity and increased the apoptosis of OCC cells. In mice implanted with OSCC cells transduced with the circ_0004771-silencing lentiviral vector, the tumor growth capacity was obviously decreased.

CONCLUSION

Silencing circ_0004771 inhibits the malignant growth of OSCC.

Biological functions of circRNA in regulating the hallmarks of gastrointestinal cancer (Review)

Circular RNA (circRNA) was first observed in the cytoplasm of eukaryotic cells in 1979, but it was not characterized in detail until 2012, when high‑throughput sequencing technology was more advanced and available. Consequently, the mechanism of circRNA formation and its biological function have been progressively elucidated by researchers. circRNA is abundant in eukaryotic cells and exhibits a certain degree of organization, timing and disease‑specificity. Additionally, it is poorly degradable, meeting the characteristics of an ideal clinical biomarker. In the present review, the recent research progress of circRNAs in digestive tract malignant tumors was primarily discussed. This included the roles, biological functions and clinical significance of circRNA, providing references for its research value and clinical potential in gastrointestinal cancer.

MicroRNAs: A novel signature in the metastasis of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a malignant epithelial tumor, characterized by squamous cell differentiation, it is the sixth leading cause of cancer-related deaths globally. The increased mortality rate of ESCC patients is predominantly due to the advanced stage of the disease when discovered, coupled with higher risk of metastasis, which is an exceedingly malignant characteristic of cancer, frequently leading to a high mortality rate. Unfortunately, there is currently no specific and effective marker to predict and treat metastasis in ESCC. MicroRNAs (miRNAs) are a class of small non-coding RNA molecules, approximately 22 nucleotides in length. miRNAs are vital in modulating gene expression and serve pivotal regulatory roles in the occurrence, progression, and prognosis of cancer. Here, we have examined the literature to highlight the intimate correlations between miRNAs and ESCC metastasis, and show that ESCC metastasis is predominantly regulated or regulated by genetic and epigenetic factors. This review proposes a potential role for miRNAs as diagnostic and therapeutic biomarkers for metastasis in ESCC metastasis, with the ultimate aim of reducing the mortality rate among patients with ESCC.

Circ_0050444 represses esophageal squamous cell carcinoma progression through sponging miR-486-3p to upregulate C10orf91

Esophageal squamous cell carcinoma (ESCC) ranks as the fourth leading cause of tumor-related deaths in China. Circ_0050444 has been revealed to be downregulated in ESCC tissues, however, its function and molecular mechanism underlying ESCC progression is unknown. Therefore, we attempted to clarify the functional role and molecular mechanism of circ_0050444 underlying ESCC progression. RT-qPCR and RNase R digestion assays were used to evaluate circ_0050444 expression and stability characteristics in ESCC cells. Gain-of-function assays were conducted to clarify circ_0050444 role in ESCC cell malignant behaviors. Bioinformatics and mechanism experiments were performed to assess the relationship between circ_0050444 or C10orf91 and miR-486-3p in ESCC cells. Rescue assays were conducted to evaluate the regulatory function of the circ_0050444-miR-486-3p-C10orf91 axis in ESCC cellular processes. Circ_0050444 expression was found to be downregulated both in ESCC patient tissues and cell lines. Functionally, circ_0050444 overexpression repressed ESCC cell proliferative, migratory, and invasive capabilities in cultured cells. Mechanistically, circ_0050444 was found to be competitively bound with miR-486-3p to upregulate C10orf91 in ESCC cells. Moreover, the impact of circ_0050444 elevation on ESCC cell proliferation, migration, and invasion was countervailed by C10orf91 silencing. Circ_0050444 presents downregulation and functions as a tumor suppressor in ESCC progression. Circ_0050444 suppresses ESCC proliferation, migration, and invasion through sponging miR-486-3p to upregulate C10orf91, providing a potential new direction for seeking therapeutic plans for ESCC.

Appraising the value of CircRNAs for the diagnosis and prognosis of esophageal squamous cell cancer: An updated meta-analysis

OBJECTIVE

The purpose of this study was to thoroughly assess the relevance of circular RNAs (circRNAs) in the diagnosis and prognosis of esophageal squamous cell carcinoma (ESCC)， and design a systematic review and meta-analysis.

METHODS

Using Stata 14.0 software, a meta-analysis was carried out by looking for pertinent studies up to February 20, 2023, in the online databases PubMed, Embase, Web of Science, and CNKI. The clinicopathologic and prognostic data were evaluated using the combined advantage ratio (OR) and combined hazard ratio (HR), respectively. The threshold effects and publication bias were quantified using Spearman's correlation and the Deeks funnel plot asymmetry tests, respectively.

RESULTS

A total of 36 pertinent studies with a literature quality score of 7 or above were included in this study. Of them, 22 papers dealt with clinicopathological characterization, 15 dealt with prognostic analysis, and 13 dealt with diagnostic analysis. The findings demonstrated that high expression of upregulated circRNAs was associated with worse clinicopathological features (tumor size: OR=3.61, 95% CI:1.45-5.78; TNM stage: OR=2.12, 95% CI:1.41-2.83; lymph node metastasis: OR=2.87, 95% CI:1.67-4.07) and worse OS (HR=1.49, 95% CI:1.26-1.77). High downregulated circRNAs expression was linked to improved clinicopathologic characteristics (TNM staging: OR=0.35, 95% CI:0.13- 0.95) and longer survival (HR=0.48, 95% CI:0.27-0.84); combined sensitivity was 0.77 (95% CI: 0.71-0.82), specificity was 0.80 (95% CI:0.74-0.86), and area under the subject operating characteristic curve (AUC) was 0.86 (95% CI:0.82- 0.88).

CONCLUSION

CircRNAs are useful for ESCC patient diagnosis and prognosis, and they are anticipated to be unique potential biomarkers for ESCC clinical diagnosis.

Exploring the dual role of circRNA and PI3K/AKT pathway in tumors of the digestive system

The interactions among circRNAs, the PI3K/AKT pathway, and their downstream effectors are intricately linked to their functional roles in tumorigenesis. Furthermore, the circRNAs/PI3K/AKT axis has been significantly implicated in the context of digestive system tumors. This axis is frequently abnormally activated in digestive cancers, including gastric cancer, colorectal cancer, pancreatic cancer, and others. Moreover, the overactivation of the circRNAs/PI3K/AKT axis promotes tumor cell proliferation, suppresses apoptosis, enhances invasive and metastatic capabilities, and contributes to drug resistance. In this regard, gaining crucial insights into the complex interaction between circRNAs and the PI3K/AKT pathway holds great potential for elucidating disease mechanisms, identifying diagnostic biomarkers, and designing targeted therapeutic interventions.

Circ_0004771 Promotes Hypoxia/Reoxygenation Induced Cardiomyocyte Injury via Activation of Mitogen-Activated Protein Kinase Signaling Pathway

This study aimed to observe the mechanism and effect of circ_0004771 on cardiomyocyte injury in acute myocardial infarction (AMI). The differences in circ_0004771 expression in the blood of AMI patients and healthy volunteers were observed by Real-Time Quantitative Reverse Transcription-Polymerase Chain Reaction. AMI cell models were constructed by hypoxia/reoxygenation (H/R)-induced injury in human cardiomyocytes (AC16 cells). The changes of circ_0004771 expression in AMI cells were observed. After transfection with the knockdown or overexpression of circ_0004771 vector in AMI cells, Cell Counting Kit-8 (CCK-8) assay and propidium iodide/FITC-Annexin V staining were performed to detect cell proliferation and apoptosis levels, extracellular lactate dehydrogenase (LDH) activity, malondialdehyde (MDA) concentration, and superoxide dismutase (SOD) activity. Expression levels of Mitogen-activated protein kinase (MAPK) signaling pathway-related proteins (p-MEK1/2, MEK1/2, p-ERK1/2, ERK1/2), and endoplasmic reticulum (ER) stress proteins (GRP78 and CHOP-1) were observed in each group of cells by western blot method. The expression level of circ_0004771 was significantly reduced in both clinical samples and cells of AMI. When circ_0004771 was knocked down in AMI cells, it resulted in a decrease in cell proliferation level and significant increase in apoptosis level. The inhibition of circ_0004771 expression caused leakage of LDH in AMI cells, accumulation of intracellular MDA, and inhibition of SOD activity. In addition, the knockdown of circ_0004771 significantly increased the levels of p-MEK1/2, p-ERK1/2, GRP78, and CHOP-1 in H/R-induced AC16 cells. However, the overexpression of circ_0004771 resulted in the opposite result as when circ_0004771 was knocked down. A low level of circ_0004771 in AMI activates the MAPK signaling pathway in cardiomyocytes as well as encourages intracellular oxidative stress and ER stress, thereby inhibiting cell proliferation and promoting apoptosis.

Curcumin inhibits esophageal squamous cell carcinoma progression through down-regulating the circNRIP1/miR-532-3p/AKT pathway

Curcumin shows an anti-cancer role in many kinds of tumors. However, the mechanism of its anti-tumor function in esophageal squamous cell carcinoma (ESCC) remains largely unknown. Herein, we explored the therapeutic potential of curcumin for esophageal cancer. Curcumin could time- and dose-dependently inhibit ESCC cells activity. Additionally, ESCC cells exposed to 20 μM of curcumin exhibited significantly decreased proliferative and invasive capacities, as well as enhanced cell apoptosis. ESCC tissues and cells exhibited significantly increased circNRIP1 expression when compared to their counterparts. circNRIP1 knockdown markedly impaired cell proliferation, clone formation, cell migration and invasion but promoted apoptosis. Exposure to 10-20 μM of curcumin inhibited circNRIP1 expression, however, overexpression of circNRIP1 could significantly restored the biological characteristics that were inhibited by curcumin exposure in vivo and in vitro. circNRIP1 promoted the malignancy of ESCC by combining miR-532-3p, and downstream AKT3. Curcumin inhibited AKT phosphorylation by up-regulating miR-532-3p expression, thereby inhibiting the activation of the AKT pathway. In summary, curcumin is a potent inhibitor of ESCC growth, which can be achieved through the regulation of the circNRIP1/miR-532-3p/AKT pathway. This research may provide new mechanisms for curcumin to inhibit the malignant development of ESCC.

MiR-671-5p sponging activity of circMMP1 promotes esophageal squamous cancer progression

BACKGROUND

The aim of this study was to explore the function and mechanism of circular RNA (circRNA) matrix metallopeptidase 1 (circMMP1) in the progression of esophageal squamous cell carcinoma (ESCC).

METHODS

CircMMP1 expression was detected by quantitative real-time PCR (qRT-PCR), and its relationship with the prognosis of ESCC patients was evaluated by Kaplan-Meier analysis. Cells were transfected using corresponding plasmids, and the cell proliferation activity, migration and invasion capabilities in vitro were assessed. The protein level in tissues and cells was analyzed using western blotting. RNA pulldown, dual-luciferase reporter assay and RNA immunoprecipitation assay were performed in ESCC cells to detect the interaction between circMMP1 and miR-671-5p, or the correlation between miR-671-5p and ANO1. Xenograft tumor experiment was carried out to uncover the function of circMMP1 in vivo.

RESULTS

The high level of circMMP1 in tumor tissues was associated with poor prognoses of ESCC patients. Knockdown of circMMP1 suppressed ESCC cell proliferation, migration and invasion in vitro. MiR-671-5p was the target of circMMP1 and mediated the inhibition effect of circMMP1 on ESCC cells. CircMMP1 targeted miR-671-5p to regulate ANO1 expression, which was downstream of miR-671-5p. Overexpression of ANO1 weakened tumor-repressive function of circMMP1 knockdown in ESCC cells. Moreover, silencing of circMMP1 impeded ESCC tumor growth in vivo.

CONCLUSION

Our study provided novel evidence that circMMP1 accelerated ESCC progression by acting as a miR-671-5p sponge to enhance ANO1 expression.

RNF149 confers cisplatin resistance in esophageal squamous cell carcinoma via destabilization of PHLPP2 and activating PI3K/AKT signalling

Chemo-resistance has been identified as a crucial factor contributing to tumor recurrence and a leading cause of worse prognosis in patients with ESCC. Therefore, unravel the critical regulators and effective strategies to overcome drug resistance will have a significant clinical impact on the disease. In our study we found that RNF149 was upregulated in ESCC and high RNF149 expression was associated with poor prognosis with ESCC patients. Functionally, we have demonstrated that overexpression of RNF149 confers CDDP resistance to ESCC; however, inhibition of RNF149 reversed this phenomenon both in vitro and in vivo. Mechanistically, we demonstrated that RNF149 interacts with PH domain and leucine rich repeat protein phosphatase 2 (PHLPP2) and induces E3 ligase-dependent protein degradation of PHLPP2, substantially activating the PI3K/AKT signalling pathway in ESCC. Additionally, we found that inhibition of PI3K/AKT signalling pathway by AKT siRNA or small molecule inhibitor significantly suppressed RNF149-induced CDDP resistance. Importantly, RNF149 locus was also found to be amplified not only in ESCC but also in various human cancer types. Our data suggest that RNF149 might function as an oncogenic gene. Targeting the RNF149/PHLPP2/PI3K/Akt axis may be a promising prognostic factor and valuable therapeutic target for malignant tumours.

CircRNA PDE3B regulates tumorigenicity via the miR-136-5p/MAP3K2 axis of esophageal squamous cell carcinoma

BACKGROUND

CircRNA has a covalently closed circular conformation and a stable structure. However, the exact role of circRNA in esophageal squamous cell carcinoma (ESCC) remains uncertain. The purpose of this study was to explore the role of hsa_circ_0000277 (circ_PDE3B) in ESCC.

METHODS

The expression levels of circ_PDE3B, miR-136-5p and mitogen-activated protein kinase kinase kinase 2 (MAP3K2) in ESCC tissues and cells were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. The proliferation ability of EC9706 and KYSE30 cells was detected by clonal formation, 5-ethynyl-2'-deoxyuridine (EdU) and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assays. Flow cytometry was used to detect the apoptosis rate of cells. Transwell assay was used to detect the invasion ability of EC9706 and KYSE3 cells. The relationship between miR-136-5p and circ_PDE3B or MAP3K2 was verified by dual-luciferase reporter assay and RNA pull-down, and the effect of circ_PDE3B on tumor growth in vivo was explored through tumor transplantation experiment. Immunohistochemistry (IHC) assay was used to detect MAP3K2 and Ki67 expression in mice tumor tissues.

RESULTS

The results showed that circ_PDE3B was highly expressed in ESCC tissues and cells. Downregulated circ_PDE3B expression in ESCC cells significantly reduced cell proliferation, migration and invasion. Circ_PDE3B served as a sponge for miR-136-5p, and miR-136-5p inhibition reversed the roles of circ_PDE3B knockdown in ESCC cells. MAP3K2 was a direct target of miR-136-5p, and miR-136-5p targeted MAP3K2 to inhibit the malignant behaviors of ESCC cells. Furthermore, circ_PDE3B regulated MAP3K2 expression by sponging miR-136-5p. Importantly, circ_PDE3B knockdown inhibited tumor growth in vivo.

CONCLUSIONS

In conclusion, circ_PDE3B acted as oncogenic circRNA in ESCC and accelerated ESCC progression by adsorption of miR-136-5p and activation of MAP3K2, supporting circ_PDE3B as a potential therapeutic target for ESCC.

Emerging roles of circ_NRIP1 in tumor development and cancer therapy (Review)

Circular RNA (circRNA) is a class of endogenous non-coding RNA, a type of single-stranded covalently closed RNA molecule formed by alternative splicing of exons or introns. Previous studies have demonstrated that circRNA participates in modulating biological processes such as cell proliferation, differentiation and apoptosis, and plays key roles in tumor occurrence and development. CircRNA nuclear receptor interacting protein 1 (circ_NRIP1), a form of circRNA, is abnormally expressed in certain human tumor types. It is present at a higher abundance compared with cognate linear transcripts and can regulate malignant biological behaviors such as tumor proliferation, invasion and migration, revealing a currently unexplored frontier in cancer progression. The present review presents a pattern of circ_NRIP1 expression in various malignant tumor types and highlights its significance in cancer development, in addition to its potential as a disease indicator or future therapeutic agent.

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

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

CircNRIP1: An emerging star in multiple cancers

Circular RNAs (circRNAs) are a new class of non-coding RNAs (ncRNAs) with a closed-loop structure that is highly stable and widely present in the eukaryotic cytoplasm. In recent years, circRNA has played a non-negligible role in the occurrence and development of a variety of diseases, which has attracted the research attention of many scholars. Circular RNA nuclear receptor interacting protein 1 (circNRIP1), a newly discovered circRNA, has been confirmed to be closely associated with cervical carcinoma (CC), colorectal cancer (CRC), esophageal squamous cell carcinoma (ESCC), gastric cancer (GC), nasopharyngeal carcinoma (NPC), non-small cell lung cancer (NSCLC), osteosarcoma (OS), ovarian cancer (OC) and papillary thyroid carcinoma (PTC). CircNRIP1 can regulate the activity of ERK1/2, PI3K/AKT, and AKT/mTOR signaling pathways. In this review, the author summarizes the biological functions and target molecular mechanisms in carcinogenesis, to point out the potential clinical values and applications of circNRIP1 in diagnosing and treating cancer.

Class IV semaphorins in disease pathogenesis

Semaphorins are a large family of secreted and/or transmembrane proteins, originally identified as proteins that function in axon guidance during neuronal development. However, semaphorins play crucial roles in other physiological and pathological processes, including immune responses, angiogenesis, maintenance of tissue homeostasis, and cancer progression. Class IV semaphorins may be present as transmembrane and soluble forms and are implicated in the pathogenesis of various diseases. This review discusses recent progress on the roles of class IV semaphorins determined by clinical and experimental pathology studies.

Regulatory Roles of Noncoding RNAs in the Progression of Gastrointestinal Cancers and Health Disparities

Annually, more than a million individuals are diagnosed with gastrointestinal (GI) cancers worldwide. With the advancements in radio- and chemotherapy and surgery, the survival rates for GI cancer patients have improved in recent years. However, the prognosis for advanced-stage GI cancers remains poor. Site-specific GI cancers share a few common risk factors; however, they are largely distinct in their etiologies and descriptive epidemiologic profiles. A large number of mutations or copy number changes associated with carcinogenesis are commonly found in noncoding DNA regions, which transcribe several noncoding RNAs (ncRNAs) that are implicated to regulate cancer initiation, metastasis, and drug resistance. In this review, we summarize the regulatory functions of ncRNAs in GI cancer development, progression, chemoresistance, and health disparities. We also highlight the potential roles of ncRNAs as therapeutic targets and biomarkers, mainly focusing on their ethnicity-/race-specific prognostic value, and discuss the prospects of genome-wide association studies (GWAS) to investigate the contribution of ncRNAs in GI tumorigenesis.

SEMA4D/PlexinB1 promotes AML progression via activation of PI3K/Akt signaling

Background

Acute myeloid leukemia (AML) is the most common type of acute leukemia in adults. SEMA4D is a 150 kDa transmembrane protein that belongs to the IV class of the subfamily of semaphorin family. Previous studies have reported that SEMA4D is a multifunctional target in many solid tumors, involving multiple physiological systems, and there are emerging therapies to target these pathways. The role of SEMA4D in AML has not yet been explored.

Methods

The SEMA4D expression prolile, clinical data and potential prognostic analysis were acquired via the cBioPortal and GEPIA databases. SEMA4D expression was measured using real-time quantitative PCR and western blot. Cell counting kit-8 (CCK8) and flow cytometry were used to evaluate the malignant biological characteristics.

Results

We observed that SEMA4D was increased in AML patients and correlated with risk stratification and prognosis. Moreover, SEMA4D promotes the proliferation and inhibits apoptosis of AML cells by binding to its receptor, PlexinB1, and reduces the sensitivity of AML cells to daunorubicin. In addition, SEMA4D/PlexinB1 promotes the proliferation and survival of AML cells by activating the PI3K/Akt signaling pathway. VX15/2503, an anti-SEMA4D antibody, can inhibit the proliferation of AML cells in xenograft mouse models, thereby inhibiting the development of AML.

Conclusion

SEMA4D will serve as a unique predictive biomarker and a possible therapeutic target in AML.

Current advances and future perspectives on the functional roles and clinical implications of circular RNAs in esophageal squamous cell carcinoma: more influential than expected

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive gastrointestinal cancers with high incidence and mortality. Therefore, it is necessary to identify novel sensitive and specific biomarkers for ESCC detection and treatment. Circular RNAs (circRNAs) are a type of noncoding RNAs featured by their covalently closed circular structure. This special structure makes circRNAs more stable in mammalian cells, coupled with their great abundance and tissue specificity, suggesting circRNAs may present enormous potential to be explored as valuable prognostic and diagnostic biomarkers for tumor. Mounting studies verified the critical roles of circRNAs in regulating ESCC cells malignant behaviors. Here, we summarized the current progresses in a handful of aberrantly expressed circRNAs, and elucidated their biological function and clinical significance in ESCC, and introduced a series of databases for circRNA research. With the improved advancement in high-throughput sequencing and bioinformatics technique, new frontiers of circRNAs will pave the path for the development of precision treatment in ESCC.

CircNRIP1 Exerts Oncogenic Functions in Papillary Thyroid Carcinoma by Sponging miR-653-5p and Regulating PBX3 Expression

Background

Circular RNA circ_0004771 (termed circNRIP1) was identified by RNA-Seq previously and was elevated in papillary thyroid carcinoma (PTC) tissues. A series of studies also showed that circNRIP1 was upregulated in some tumors and could promote the malignant progression of tumors. This research intended to focus on the role of circNRIP1 in PTC progression and explore the mechanisms underlying circNRIP1 functions.

Methods

RT-PCR or western blot determined circNRIP1, miR-653-5p, and pre-B-cell leukemia homeobox 3 (PBX3) expression. EdU, CCK-8, Tunel, and transwell assays determined cell proliferation, apoptosis, invasion, and migration, respectively. Luciferase reporter assay, RNA immunoprecipitation (RIP), and RNA pull down assays clarified the target relation between miR-653-5p and circNRIP1 or PBX3. Xenograft models were applied to explore the role of circNRIP1 in vivo.

Results

circNRIP1 significantly increased in PTC tissues and PTC cell lines than that in normal ones. Higher circNRIP1 expression was associated with the TNM stage and poorer overall survival. circNRIP1 knockdown attenuated the malignant progression of PTC, specifically by inhibiting proliferation and invasion/migration and promoting apoptosis. circNRIP1 was a miR-653-5p sponge; miR-653-5p knockdown reversed the suppressive role of circNRIP1 silence in PTC progression. PBX3, a target of miR-653-5p, was positively medicated through circNRIP1 via competitively sponging miR-653-5p. Knockdown of circNRIP1 attenuated the PTC tumor progression via miR-653-5p/PBX3 axis.

Conclusion

Silencing of circNRIP1 suppressed PTC development via miR-653-5p elevation and PBX3 reduction, providing a novel perspective for understanding PTC pathogenesis.