CircCCNB1 Knockdown Blocks the Progression of Cervical Cancer by Acting as Competing Endogenous RNA in the miR-370-3p/SOX4 Pathway

OBJECTIVE

Cervical cancer is one of the leading causes of cancer-related death in women, which has been shown to be associated with the deregulation of circular RNAs (circRNAs). The aim of this study was to determine the role of circRNA cyclin B1 (circCCNB1) in cervical cancer.

METHODS

The expression of circCCNB1, microRNA-370-3p (miR-370-3p), and SRY-box transcription factor 4 (SOX4) mRNA was detected by quantitative real-time PCR (qPCR). Functional experiments, including colony formation assay, EdU assay, transwell assay and flow cytometry assay, were performed. Lactate production and glucose uptake were examined to assess glycolysis metabolism. The protein levels of glycolysis-related markers and SOX4 were detected by western blot. The interaction between miR-370-3p and circCCNB1 or SOX4 was verified by dual-luciferase reporter, RIP, and pull-down assay. Xenograft assay was performed to monitor the role of circCCNB1 in animal models.

RESULTS

CircCCNB1 was highly expressed in cervical cancer tissues and cells (squamous cell carcinoma and adenocarcinoma cells). The knockdown of circCCNB1 inhibited cell proliferation, migration, invasion and glycolysis metabolism, and induced cell apoptosis. CircCCNB1 functioned as miR-370-3p sponge to suppress miR-370-3p expression and function. Moreover, circCCNB1 inhibited the expression of miR-370-3p to increase the expression of SOX4. MiR-370-3p inhibition reversed the effects of circCCNB1 knockdown and thus promoted cell proliferation, migration, invasion and glycolysis. SOX4 overexpression reversed the effects of miR-370-3p restoration and thus promoted cell proliferation, migration, invasion and glycolysis.

CONCLUSION

CircCCNB1 knockdown blocks cervical cancer development by targeting the miR-370-3p/SOX4 pathway.

Circular RNA circCCNB1 inhibits the migration and invasion of nasopharyngeal carcinoma through binding and stabilizing TJP1 mRNA

Nasopharyngeal carcinoma (NPC) is a malignant tumor that usually occurs in people from Southeast Asia and Southern China. NPC is prone to migration and invasion, leading to poor prognosis. A large number of circular RNAs (circRNAs) exacerbate the process of metastasis in NPC; however, their underlying mechanisms remain unclear. We found that the circular RNA circCCNB1, encoded by the oncogene CCNB1, was downregulated in NPC biopsies and cell lines. In vitro assays show that circCCNB1 inhibits NPC cell migration and invasion. Moreover, circCCNB1 induces a protein, nuclear factor 90 (NF90), to bind and prolong the half-life of tight junction protein 1 (TJP1) mRNA. Upregulation of TJP1 enhances tight junctions between cancer cells and inhibits NPC cell migration and invasion. This study reveals a novel biological function of circCCNB1 in the migration and invasion of NPC by enhancing the tight junctions of cancer cells by binding to NF90 proteins and TJP1 mRNA, and may provide a potential therapeutic target for NPC.

EIF4A3-induced circCCNB1 (hsa_circ_0001495) promotes glioma progression by elevating CCND1 through interacting miR-516b-5p and HuR

To explore the functions of circRNA cyclin B1 (circCCNB1) in glioma and its possible mechanisms. The expression of circCCNB1, eukaryotic translation initiation factor 4A3 (EIF4A3), cyclin D1 (CCND1) and miR-516b-5p was determined by qRT-PCR, western blot or immunohistochemistry (IHC) assay. The feature of circCCNB1 was analyzed by Actinomycin D (ActD), RNase R and subcellular fraction assays. The molecule relationships were analyzed by RIP, dual-luciferase reporter and RNA pull-down assays. CCK-8, EdU and colony formation assays were performed to analyze cell proliferation. Flow cytometry analysis was executed to estimate the cell cycle. Murine xenograft model assay was used for the role of circCCNB1 in vivo. CircCCNB1 was overexpressed in glioma tissues and cells. EIF4A3 positively regulated circCCNB1 expression. CircCCNB1 knockdown repressed glioma cell proliferation and cell cycle process in vitro and blocked tumor growth in vivo. CircCCNB1 knockdown reduced CCND1 expression in glioma cells and CCND1 overexpression bated the effect of circCCNB1 knockdown on glioma cell growth. CircCCNB1 interacted with HuR to elevate CCND1 expression. miR-516b-5p could interact with circCCNB1 and CCND1. CircCCNB1 regulated glioma cell progression and CCND1 expression by miR-516b-5p and HuR. CircCCNB1 aggravated glioma cell growth by elevating CCND1 through targeting miR-516b-5p and HuR.

CircCCNB1 silencing acting as a miR-106b-5p sponge inhibited GPM6A expression to promote HCC progression by enhancing DYNC1I1 expression and activating the AKT/ERK signaling pathway

Background: Circular RNAs (circRNAs), which generally act as microRNA (miRNA) sponges to competitively regulate the downstream target genes of miRNA, play an essential role in cancer biology. However, few studies have been reported on the role of circRNA based competitive endogenous RNA (ceRNA) network in hepatocellular carcinoma (HCC). Herein, we aimed to screen and establish the circRNA/miRNA/mRNA networks related to the prognosis and progression of HCC and further explore the underlying mechanisms of tumorigenesis. Methods: GEO datasets GSE97332, GSE108724, and GSE101728 were utilized to screen the differentially expressed circRNAs (DE-circRNAs), DE-miRNAs, and DEmRNAs between HCC and matched para-carcinoma tissues. After six RNA-RNA predictions and five intersections between DE-RNAs and predicted RNAs, the survival-related RNAs were screened by the ENCORI analysis tool. The ceRNA networks were constructed using Cytoscape software, based on two models of up-regulated circRNA/down-regulated miRNA/up-regulated mRNA and down-regulated circRNA/up-regulated miRNA/down-regulated mRNA. The qRT-PCR assay was utilized for detecting the RNA expression levels in HCC cells and tissues. The apoptosis, Edu, wound healing, and transwell assays were performed to evaluate the effect of miR-106b-5p productions on the proliferation, invasion, and metastasis of HCC cells. In addition, the clone formation, cell cycle, and nude mice xenograft tumor assays were used to investigate the influence of hsa_circ_0001495 (circCCNB1) silencing and overexpression on the proliferation of HCC cells in vitro and in vivo. Furthermore, the mechanism of downstream gene DYNC1I1 and AKT/ERK signaling pathway via the circCCNB1/miR-106b-5p/GPM6A network in regulating the cell cycle was also explored. Results: Twenty DE-circRNAs with a genomic length less than 2000bp, 11 survival-related DE-miRNAs, and 61 survival-related DE-mRNAs were screened out and used to construct five HCC related ceRNA networks. Then, the circCCNB1/miR-106b-5p/GPM6A network was randomly selected for subsequent experimental verification and mechanism exploration at in vitro and in vivo levels. The expression of circCCNB1 and GPM6A were significantly down-regulated in HCC cells and cancer tissues, while miR-106b-5p expression was up-regulated. After transfections, miR-106b-5p mimics notably enhanced the proliferation, invasion, and metastasis of HCC cells, while the opposite was seen with miR-105b-5p inhibitor. In addition, circCCNB1 silencing promoted the clone formation ability, the cell cycle G1-S transition, and the growth of xenograft tumors of HCC cells via GPM6A downregulation. Subsequently, under-expression of GPM6A increased DYNC1I1 expression and activated the phosphorylation of the AKT/ERK pathway to regulate the HCC cell cycle. Conclusions: We demonstrated that circCCNB1 silencing promoted cell proliferation and metastasis of HCC cells by weakening sponging of oncogenic miR-106b-5p to induce GPM6A underexpression. DYNC1I1 gene expression was up-regulated and further led to activation of the AKT/ERK signaling pathway.