Circular RNA circBACH2 plays a role in papillary thyroid carcinoma by sponging miR-139-5p and regulating LMO4 expression

Non-coding RNA in thyroid cancer - Functions and mechanisms

Thyroid cancer is the most common endocrine malignant tumor, and its incidence has increased significantly in the past few years. A growing number of noncoding RNAs (ncRNAs) have shown abnormal expression patterns in human thyroid cancer in recent studies. Depending on size, ncRNAs are usually subdivided into two categories: short ncRNAs and long ncRNAs (longer than 200 nucleotides). Short ncRNAs include microRNAs (miRNAs), PIWI-interacting RNAs, small nucleolar RNAs, and endogenous small interfering RNAs, which have been extensively studied due to their roles in developmental and tumor biology. Compared to that of short ncRNAs, the involvement of lncRNAs in human cancers, especially in thyroid cancer, is not as well studied. Here, we reviewed the roles and clinical significance of miRNAs, lncRNAs, and circular RNA in thyroid development, tumorigenesis, and metastasis to offer a new approach to thyroid cancer treatment.

The combination of circRNA-UMAD1 and Galectin-3 in peripheral circulation is a co-biomarker for predicting lymph node metastasis of thyroid carcinoma

The diagnosis of lymph node metastasis (LNM) by liquid biopsy is a novel concept prompted by the necessity to develop a more convenient and accurate method to guide the clinical management of early LNM in papillary thyroid carcinoma (PTC). However, the sensitivity and specificity of many biomarkers are not high enough. We aimed to detect circRNAs from peripheral circulation that may be better associated with the prognosis of LNM in PTC. First, Galectin-3 (Gal3) in blood was determined to be highly expressed in LNM patients. Second, based on a bioinformatics analysis and miRNA sequencing analysis from 2 paired primary and LNM tumors, miR-873 was identified to directly target Gal3, which was significantly associated with clinical parameters including LNM. Third, from additional circRNA sequencing, circRNA-UMAD1 was selected as a specific sponge for miR-873 and was correlated with Gal3 levels in peripheral circulation. Fourth, circRNA-UMAD1 and Gal3 were identified to have stronger co-biomarker potential with relatively high expression in the serum of LNM patients compared with primary tumor patients, as demonstrated by the RNA expression levels in the serum of 50 PTC patients with or without LNM by quantitative real-time PCR. Overall, the combination of circRNA-UMAD1 and Gal3 is a useful and effective co-biomarker for the prognosis of LNM in PTC patients. This new molecular typing method for LNM in PTC is more precise.

LncRNA TTN-AS1 promotes the progression of oral squamous cell carcinoma via miR-411-3p/NFAT5 axis

Background

Oral squamous cell carcinoma (OSCC) is a common kind of squamous cell carcinoma of the head and neck, which is a threat to public health. Long noncoding RNAs (lncRNAs) are associated with the development of various diseases, including cancers. LncRNA titin antisense RNA 1 (TTN-AS1) is known as a crucial regulatory factor in several cancers. Nevertheless, the specific functions of TTN-AS1 in OSCC remains obscure.

Methods

The expression of TTN-AS1 in OSCC samples or cells was analyzed through qRT-PCR. Colony formation assay, EdU assay, flow cytometry assay, TUNEL assay and wound healing assay were conducted to estimate the functions of TTN-AS1 in OSCC cells. RIP and luciferase reporter assays were utilized to detect the interaction between TTN-AS1 and miR-411-3p as well as between miR-411-3p and NFAT5.

Results

TTN-AS1 expression was stronger in OSCC cells. Knockdown of TTN-AS1 effectively restrained cell proliferation and migration but had inductive role in apoptosis. Moreover, TTN-AS1 could function as the miR-411-3p sponge in OSCC and miR-411-3p exerted the inhibitory functions on OSCC cell growth. In addition, NFAT5 was proven as the target of miR-411-3p. Rescue assay indicated that overexpressing NFAT5 could reverse the inhibitory function of TTN-AS1 depletion on cell growth.

Conclusion

lncRNA TTN-AS1 contributed to the progression of OSCC via miR-411-3p/NFAT5 axis.

Circular RNA DOCK1 downregulates microRNA-124 to induce the growth of human thyroid cancer cell lines

BACKGROUND

Both circular RNA DOCK1 (circDOCK1) and microRNA-124 (miR-124) are implicated in carcinogenesis, but functional association between these two molecules remains uncharacterized. Here, we aimed to ascertain the role of circDOCK1-miR-124 node in thyroid cancer cells.

METHODS

circDOCK1 in thyroid cancer specimens from 25 patients was quantified by qRT-PCR. FTC-133 and TPC-1 cells were enforced to overproduce circDOCK1 and miR-124 which were confirmed by qRT-PCR. The alteration in viability, migration and invasion was monitored. Cellular lysis was subjected to Western blot for detecting cyclin D1, p53, matrix metallopeptidase 9 (MMP-9), and vimentin. The phosphorylation of JAK1, STAT3, and AMPK was determined by Western blot.

RESULTS

Results from qRT-PCR showed circDOCK1 was enriched in thyroid carcinoma tissues. circDOCK1 fortified the viability of FTC-133 and TPC-1 cells, as well as their activities to migrate and invade. circDOCK1 increased cyclin D1 and decreased p53, and meanwhile induced the accumulation of MMP-9 and vimentin. miR-124 conferred a reverse effect on the abovementioned alteration. Besides, miR-124 blockaded the phosphorylation of JAK1, STAT3, and AMPK which was induced by circDOCK1.

CONCLUSION

circDOCK1 contributed to thyroid carcinogenesis through inhibition of miR-124 in thyroid cancer cells with dampening signaling transduction of JAK/STAT/AMPK in virtue of miR-124 downregulation.

Diagnostic, prognostic, and therapeutic significance of miR-139-5p in cancers

miRNAs are a group of non-coding RNAs that have regulatory functions in post-transcriptional gene expression. These molecules play a fundamental role in cellular processes, for instance cell proliferation, apoptosis, migration, and invasion. Scientific investigations have previously established that miRNAs can either promote or suppress tumor development by mediating different signaling pathways. miR-139-5p, located on chromosome 11q13.4, has been examined extensively in cancers. Studies have demonstrated that miR-139-5p might be an attractive cancer biomarker. Herein, we will review how miR-139-5p acts in cancer diagnosis, prognosis, and therapy, as well as elucidating its major target genes and associated signaling pathways.

circ_0000638 inhibits neodymium oxide-induced bronchial epithelial cell inflammation through the miR-498-5p/NF-κB axis

Inhalation of neodymium oxide, a type of rare earth metal, can induce various respiratory diseases, such as lung tissue inflammation, but the associated mechanisms underlying this induction are still unclear. In this study, we explored the role and mechanisms of circular RNA in neodymium oxide-induced airway inflammation. Our study showed that treating human bronchial epithelial (16HBE) cells with neodymium oxide caused an inflammatory response by upregulating the expression of interleukin-8 (IL-8) and interleukin-1 beta (IL-1β). Quantitative real-time polymerase chain reaction (qRT-PCR) analyses revealed significant downregulation of circRNA_0000638 in neodymium oxide-treated 16HBE cells. Data from functional analyses further showed that circ_0000638 inhibited inflammation induced by neodymium oxide in 16HBE cells. circ_0000638 targeted miR-498-5p and further increased the expression of NKRF (NF-κB repressing factor), which inhibited the activation of NF-κB (nuclear factor κB). Moreover, circ_0000638 reduced the expression of IL-8 and IL-1β by inhibiting NF-κB activation in neodymium oxide-treated 16HBE cells. These results suggest that circ_0000638 can inhibit NF-κB activation by competitively binding to miR-498-5p, further downregulating the expression of IL-8 and IL-1β in neodymium oxide-treated 16HBE cells.

CircRNAs: potency of protein translation and feasibility of novel biomarkers and therapeutic targets for head and neck cancers

Circular RNAs (circRNAs), a new star noncoding RNA (ncRNA), show stability, conservation, abundance, and tissue and stage specificity. They act as key regulators of biological processes. They target the mRNAs of many other different genes or signaling pathways, and closely link associated genes into regulatory networks. Growing evidence has demonstrated that circRNAs may play an important role in the carcinogenesis, progression and chemoradiation resistance of many cancers including head and neck cancers (HNC). CircRNA, like other ncRNA, such as miRNA, lncRNA, usually is considered to be non-protein coding transcript. However, recent studies indicated that abnormal translation of circRNAs may be involved in human diseases. In this review, we collected the origin, classification, characteristics, function of circRNAs, exosmal circRNAs, and then synthesize current study results to highlight aberration of circRNAs in various types of HNC, and try to clarify the molecular mechanisms of circRNAs affecting the pathogenesis and progression of HNC, as well as pay particular attention to provide a new avenue to the diagnosis and treatment strategy for HNC.

Circular RNA CircPRMT5 Accelerates Proliferation and Invasion of Papillary Thyroid Cancer Through Regulation of miR-30c/E2F3 Axis

Background

The role of circular RNA (circRNA) in papillary thyroid cancer (PTC) is largely unknown. This study aims to determine the function and mechanism of circPRMT5 in the regulation of PTC development.

Methods

PTC tissues and cell lines were used to determine circPRMT5 expression via quantitative real-time polymerase chain reaction. Small interfering RNA (siRNA) was utilized to knock down circPRMT5. Proliferation was analyzed through CCK8 and colony formation assays. Transwell assay was performed to determine cell migration and invasion. Luciferase assay and RIP assay were carried out to analyze the interaction between circPRMT5 and miR-30c.

Results

CircPRMT5 expression was upregulated in PTC tissues and cell lines. And circPRMT5 level was positively linked with advanced stage and lymph node metastasis. CircPRMT5 knockdown inhibited proliferation, migration and invasion while inducing apoptosis. CircPRMT5 worked as a competing endogenous RNA for miR-30c. By inhibiting miR-30c, circPRMT5 promoted the expression of E2F3.

Conclusion

Our findings demonstrate that circPRMT5 acts as an oncogenic circRNA to promote PTC progression via regulating miR-30c/E2F3 axis.

Exosome-transmitted circ_MMP2 promotes hepatocellular carcinoma metastasis by upregulating MMP2

Exosomes released by tumor cells have been recently identified as important determinants of tumor progression. They often carry circular RNAs that are differentially expressed in tumors and may regulate tumorigenesis and metastasis. Here, we showed that supernatant of 97H hepatocellular carcinoma (HCC) cell line could promote metastasis in L02 human liver cells and HCC cell lines. Moreover, we determined that circ_MMP2 (has_circ_0039411) could be delivered by 97H‐ or LM3 cell‐derived exosomes to L02 and HepG2 cell cultures. High expression of circ_MMP2 led to the upregulation of its host gene matrix metallopeptidase 2 (MMP2) via the sponging of miR‐136‐5p. Rescue assays demonstrated that miR‐136‐5p and MMP2 were two essential participants in HCC metastasis. Finally, high level of circ_MMP2 or MMP2, as well as low level of miR‐136‐5p, was correlated with low overall survival of HCC patients. Our study highlights a novel molecular pathway in HCC cell‐derived exosomes.

Biological Roles and Mechanisms of Circular RNA in Human Cancers

Circular RNA (circRNA) is an intriguing class of RNA with covalently closed-loop structure and is highly stable and conservative. As new members of the ncRNAs, the function, mechanism, potential diagnostic biomarker, and therapeutic target have raised increased attention. Most circRNAs are presented with characteristics of abundance, stability, conservatism, and often exhibiting tissue/developmental-stage-specific manner. Over 30,000 circRNAs have been identified with their unique structures to maintain stability more easily than linear RNAs. An increased numbers of circRNAs are dysregulated and involved in several biological processes of malignance, such as tumorigenesis, growth, invasion, metastasis, apoptosis, and vascularization. Emerging evidence suggests that circRNAs play important roles by acting as miRNA sponge or protein scaffolding, autophagy regulators, and interacting with RNA-binding protein (RBP), which may potentially serve as a novel promising biomarker for prevention, diagnosis and therapeutic target for treatment of human cancer with great significance either in scientific research or clinic arena. This review introduces concept, major features of circRNAs, and mainly describes the major biological functions and clinical relevance of circRNAs, as well as expressions and regulatory mechanisms in various types of human cancer, including pathogenesis, mode of action, potential target, signaling regulatory pathways, drug resistance, and therapeutic biomarkers. All of which provide evidence for the potential utilities of circRNAs in the diagnosis and treatment of cancer.

Insights into the regulatory role of circRNA in angiogenesis and clinical implications

Angiogenesis is the physiological process of new blood vessel formation from existing capillary vessels or posterior capillary veins. Its dysfunction could result in a number of diseases, such as cardiovascular diseases and cancer, contributing to death and disability worldwide. Circular RNAs (circRNAs) are a class of novel identified RNA molecules with a special covalent loop structure without a 5' cap and 3' tail, which can lead to novel back-splicing or skipping events from precursor mRNAs. Accumulating evidence suggests that circRNA play critical roles in diseases; in particular, they are abundantly and abnormally expressed in angiogenesis-related diseases. In this review, we describe the role of circRNA under pathological conditions, discuss the association between circRNA and angiogenesis, classify the regulatory mechanisms and suggest that circRNA can be used as potential therapeutic targets for angiogenesis-related diseases under clinical evaluation.

Circular RNA Profiling Reveals Exosomal circ_0006156 as a Novel Biomarker in Papillary Thyroid Cancer

Circular RNAs (circRNAs) are a class of noncoding RNAs that are broadly expressed in various biological cells and function in regulating gene expression. However, the molecular mechanisms that link circRNAs with progression of papillary thyroid carcinoma (PTC) are not well understood. In the present study, the function of circ_0006156 (circFNDC3B) was investigated in human PTC cells. First, we detected the expression of circFNDC3B in PTC tissues and PTC cell lines by RT-PCR. A luciferase reporter assay and AGO2-RNA immunoprecipitation (RIP) was used to confirm the relationship between circFNDC3B and microRNA (miR)-1178. PTC cells were stably transfected with small interfering RNA (siRNA) against circFNDC3B, and cell proliferation, migration, and invasion were detected to evaluate the effect of circFNDC3B in PTC, while tumorigenesis was assayed in nude mice. In this study, circFNDC3B was observed to be upregulated in PTC tissues and cell lines. Knockdown of circFNDC3B inhibited cell proliferation and promoted cell apoptosis in PTC cells. Bioinformatics analysis predicted that there is a circFNDC3B/miR-1178/Toll-like receptor 4 (TLR4) axis in PTC. The dual-luciferase reporter system validated the direct interaction of circFNDC3B, miR-1178, and TLR4. Furthermore, circFNDC3B facilitates PTC progression in vivo. Importantly, we demonstrated that circFNDC3B was upregulated in serum exosomes from PTC patients. In summary, our study demonstrated that circFNDC3B modulates PTC progression through the miR-1178/TLR4 pathway. Our findings indicated that circFNDC3B may serve as a promising therapeutic target for the treatment of PTC patients.

Advances on circRNAs Contribute to Carcinogenesis and Progression in Papillary Thyroid Carcinoma

In view of the highly increased prevalence of papillary thyroid carcinoma (PTC) year by year, it is of great importance to explore new molecular targets for anticancer strategies. Emerging evidence indicates that circular RNAs (circRNAs), characterized by a closed-loop structure and high stability, play important roles in tumorigenesis and development of human cancer by regulating multiple complex biological processes, such as cellular proliferation, metastasis, and metabolism. A comprehensive understanding of the roles of circRNAs will facilitate the development of promising future therapeutic strategies for treating cancers, including PTC. In this paper, we review the profile of circRNA in PTC, its regulatory roles, and the pathological mechanism as well as their related clinical significance. In addition, challenges of this specific field are discussed.

Identification and characterization of novel type of RNAs, circRNAs in crucian carp Carassius auratus gibelio

Circular RNAs (circRNAs) with regulatory potency activity was identified from varieties of species. Crucian carp (Carassius auratus gibelio) is one of the most freshwater aquaculture species in China. Every year, huge economic damage to the farming was caused by the virus and bacterial infection. Until now, there is any information about circRNA reported from the Crucian carp. In this study, the expression pattern of circRNA in Crucian carp was investigated with transcriptomic analysis. The results showed that only 37 circRNAs were identified from the Crucian carp, and these circRNAs biogenesis was formed with canonical GU-AG splicing mechanism with unevenly distributed on the chromosomes. Wherein, most of the circRNAs were derived from the sense overlapping strategy. Reverse transcript PCR and Sanger sequencing data indicated that these circRNAs were existed authenticity in Crucian carp. The bioinformatics analysis indicated that circRNAs identified from the Crucian carp with potential miRNA sponge regulate the expression level of mRNAs. GO annotation and KEGG pathway analysis of these circRNAs showed that more than 20% circRNAs were related with catalytic activity and binding in the category of molecular function, and these circRNAs were enriched in 9 signaling pathways, such as, Wnt signaling pathway, MAPK signaling pathway, Ubiquitin mediated proteolysis et al. 220 mRNAs would be regulated by the circRNAs via miRNAs mediation. These target mRNAs were further analyzed with functional annotation and KEGG analysis. GO annotation analysis showed that several genes were related with function of nucleotide binding, transcription regulatory activity. KEGG pathway analysis showed that 5 genes were enriched in the pathway of Endocytosis. The circRNA-miRNA-mRNA regulation network indicated that one miRNA can link one or more circRNA and one or more mRNA. Overall, these results will not only help us to further understand the novel RNA transcripts in Crucian carp, but also provide the novel clue to investigate the interaction between host and pathogens from this novel circRNA molecule.

Circular RNA circ-PRMT5 facilitates non-small cell lung cancer proliferation through upregulating EZH2 via sponging miR-377/382/498

Emerging evidence demonstrates that circular RNA (circRNA) is a novel class of non-coding RNA that plays a pivotal role in cancer. Recently, circ-PRMT5 was identified as an oncogene in bladder cancer. Nevertheless, its contribution to non-small cell lung cancer (NSCLC) is unknown. Herein, we aimed to clarify the biological role of circ-PRMT5 in NSCLC. High circ-PRMT5 expression was identified in NSCLC tissues and cell lines and positively correlated with larger tumor size, advanced clinic stage, lymph node metastasis as well as worse prognosis. Stable knockdown of circ-PRMT5 dramatically weakened the proliferative capacities of NSCLC cells both in vitro and in vivo. Mechanically, circ-PRMT5 could simultaneously effectively sponge three miRNAs (miR-377, miR-382 and miR-498) and alleviate their repression on the well-known oncogenic EZH2, resulting in increased EZH2 expression, thereby facilitating NSCLC progression. Importantly, a strong positive correlation between circ-PRMT5 and EZH2 expression was observed in NSCLC tissues. Overall, our data indicate that circ-PRMT5 is an oncogenic circRNA in NSCLC that can promote the growth of NSCLC via regulation of miR-377/382/498-EZH2 axis.

Integration of Bioinformatic Predictions and Experimental Data to Identify circRNA-miRNA Associations

Circular RNAs (circRNAs) have recently emerged as a novel class of transcripts, characterized by covalently linked 3'-5' ends that result in the so-called backsplice junction. During the last few years, thousands of circRNAs have been identified in different organisms. Yet, despite their role as disease biomarker started to emerge, depicting their function remains challenging. Different studies have shown that certain circRNAs act as miRNA sponges, but any attempt to generalize from the single case to the "circ-ome" has failed so far. In this review, we explore the potential to define miRNA "sponging" as a more general function of circRNAs and describe the different approaches to predict miRNA response elements (MREs) in known or novel circRNA sequences. Moreover, we discuss how experiments based on Ago2-IP and experimentally validated miRNA:target duplexes can be used to either prioritize or validate putative miRNA-circRNA associations.

Circular RNA circNHSL1 promotes gastric cancer progression through the miR-1306-3p/SIX1/vimentin axis

Background

Mounting evidences indicate that circular RNAs (circRNAs) play vital roles in the development and progression of various cancers. However, the detail functions and underlying mechanisms of circRNAs in gastric cancer remain largely unknown.

Methods

The expression profile of metastasis-related circRNAs was screened by RNA-seq analysis. qRT-PCR was used to determine the level and prognostic values of circNHSL1 in gastric cancer tissues. In vitro cell wound healing and transwell (migration and invasion) and in vivo tumorigenesis and metastasis assays were performed to evaluate the functions of circNHSL1. Luciferase reporter, RNA immunoprecipitation (RIP) and rescued assays were employed to confirm the interactions between circNHSL1, miR-1306-3p and SIX1. It’s widely accepted that as a mesenchymal marker, Vimentin promotes invasion and metastasis in various cancers. Luciferase reporter assay was used to determine the regulation of SIX1 on Vimentin. In addition, In situ hybridization (ISH) was performed to detect the level and prognostic values of miR-1306-3p.

Results

We found that the level of circNHSL1 was significantly up-regulated in gastric cancer, and positively correlated with clinicopathological features and poor prognosis of patients with gastric cancer. Functionally, circNHSL1 promoted cell mobility and invasion, as well as in vivo tumorgenesis and metastasis. Mechanistically, circNHSL1 acted as a miR-1306-3p sponge to relieve the repressive effect of miR-1306-3p on its target SIX1. Moreover, SIX1 enhanced Vimentin expression in the transcriptional level through directly binding to the promoter domain of Vimentin, thereby promoting cell migration and invasion. In addition, miR-1306-3p was down-regulated and negatively correlated with pathological features and poor prognosis in gastric cancer.

Conclusions

CircNHSL1 promotes gastric cancer progression through miR-1306-3p/SIX1/Vimentin axis, and may serve as a novel diagnostic marker and target for treatment of gastric cancer patients.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-1054-7) contains supplementary material, which is available to authorized users.

Circular RNA circ-ADD3 inhibits hepatocellular carcinoma metastasis through facilitating EZH2 degradation via CDK1-mediated ubiquitination

Emerging evidence suggests that circular RNA (circRNA) plays a fundamental role in tumorigenesis. However, its contribution to hepatocellular carcinoma (HCC) malignancy remains largely unknown. Here, we performed circRNA microarray expression profile in four paired HCC and normal tissues, and found that circ-ADD3, a novel circRNA derived from linear ADD3 exon 4 to exon 12, was significantly downregulated in HCC, which was further validated in 112 matched HCC and paracancerous tissues. High circ-ADD3 expression was negatively correlated with vascular invasion, intrahepatic metastasis as well as distant metastasis. Moreover, it was identified as an effective biomarker for diagnosis and prognosis of HCC. Functionally, exogenous expression of circ-ADD3 dramatically weakened HCC cell invasion and metastasis both in vitro and in vivo. Mechanistically, circ-ADD3 was capable of reinforcing the interaction between CDK1 and EZH2, resulting in increased EZH2 ubiquitination and subsequent degradation via phosphorylation at Thr-345 and Thr-487 sites. The decreased EZH2 markedly increased the expression of a cohort of anti-metastatic genes, including circ-ADD3, by reducing H3K27me3 levels on their promoter regions, which formed a regulatory circuit, thereby dampening HCC metastasis. Taken together, our findings unveil the essential role of circ-ADD3 in inhibiting HCC metastasis through regulation of EZH2 stability.

Upregulated Circular RNA circ-UBE2D2 Predicts Poor Prognosis and Promotes Breast Cancer Progression by Sponging miR-1236 and miR-1287

Emerging evidence suggests that circular RNAs (circRNAs) are linked to the development and progression of human cancers. Nevertheless, their contribution to breast cancer (BC) is still largely unknown. In the current study, we screened and identified a novel circRNA, circ-UBE2D2, which was highly expressed in BC cell lines and tissues and was closely related to aggressive clinical features and dismal prognosis. Small interfering RNA (siRNA)–mediated circ-UBE2D2 silencing notably inhibited the proliferation, migration and invasion of BC cells, whereas circ-UBE2D2 overexpression displayed opposite effects. Mechanistically, circ-UBE2D2 was able to simultaneously function as molecular sponges of miR-1236 and miR-1287 to regulate the expression of their respective target genes. Moreover, circ-UBE2D2–induced tumor-promoting effects could be effectively blocked by miR-1236 or miR-1287 in BC cells. More importantly, therapeutic delivery of cholesterol-conjugated si-circ-UBE2D2 oligonucleotides significantly delayed tumor growth in vivo. Overall, our findings indicate that circ-UBE2D2 plays an essential oncogenic role in BC, and targeting circ-UBE2D2 may be a feasible treatment for BC patients.

hsa_circ_0000745 promotes cervical cancer by increasing cell proliferation, migration, and invasion

Circular RNAs (circRNAs) participate in gene regulation and malignant tumor progression, including uterine cervical cancer (CC). In this study, the expression profile of circRNAs in CC was detected using circRNA microarrays. Then, we selected hsa_circ_0000745 for further examination from the significantly dysregulated circRNAs. Proliferation assays, Transwell assays, quantitative reverse transcription polymerase chain reaction, western blot analysis and tumorigenesis tests in vivo were used to validate the role of hsa_circ_0000745 in CC. hsa_circ_0000745 was upregulated in CC, and its level positively correlated with the level of its linear messenger RNA isoform. Patients with poorly differentiated tumors or vascular/lymphatic invasion presented higher expression of hsa_circ_0000745. The role of hsa_circ_0000745 was illuminated by knocking down hsa_circ_0000745 in CC cells, and the results revealed that reducing hsa_circ_0000745 inhibited cell proliferation, migration, and invasion in CC by upregulating E‐cadherin (E‐cad) expression. In summary, as a tumor promoter in CC, hsa_circ_0000745 enhances the cell's ability to proliferate, migrate, and invade by reducing the expression of E‐cad. hsa_circ_0000745 is a candidate target for the treatment of CC in the clinic.