Circular RNA circ-ADD3 inhibits hepatocellular carcinoma metastasis through facilitating EZH2 degradation via CDK1-mediated ubiquitination.
ABSTRACT: 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.
Project description:Abnormal circular RNA (circRNA) expression correlates with human traits such as many kinds of cancers. Though circRNAs have links to cancer, they have less characterization in metastatic castration-resistant prostate cancer (PCa), which is main reason for PCa mortality. Therefore, high-throughput sequencing was used for selected circRNA profiles. The result showed that circ-TRPS1 was upregulated significantly in high-grade PCa tissues or cell lines. High circ-TRPS1 expression correlated to aggressive PCa phenotypes. Knockdown of circ-TRPS1 suppressed PCa proliferation and metastasis through targeting miR-124-3p/EZH2 axis-mediated stemness in PCa, which was validated by luciferase reporter assays. EZH2 overexpression or miR-124-3p inhibition reversed the inhibition of circ-TRPS1 silencing in PCa cell migration and proliferation by recovering stemness. In summary, data demonstrated that circ-TRPS1 suppressed PCa progression through functioning similar to a miR-124-3p sponge to enhance EZH2 expression and cancer stem-like cell differentiation. Thus, circ-TRPS1 might be a candidate target for PCa treatment.
Project description:Purpose:Circular RNAs (circRNAs) play important roles in the development and progression of various human cancers. hsa-circ-0046600 is a circRNA of unknown function. The purpose of this study was to investigate the biological function of hsa-circ-0046600 in hepatocellular carcinoma (HCC) and elucidate the possible molecular mechanisms of this circRNA. Materials and methods:GSE97332, quantitative reverse transcription polymerase chain reaction (qRT-PCR) and fluorescence in situ hybridization (FISH) were used to detect the expression of hsa-circ-0046600 in HCC tissues and cells. A dual-luciferase reporter assay was used to confirm the interaction between hsa-circ-0046600 and miR-640, and a meta-analysis confirmed the expression of miR-640 in HCC. Bioinformatics was used for the functional analysis of miR-640 target genes. N-cadherin and HIF-1? expression was measured by Western blot analysis. Results:The expression level of hsa-circ-0046600 in HCC tissue was significantly higher than that in adjacent normal tissue (P < 0.05) and was associated with tumour size, TNM stage and pathological vascular invasion. Moreover, the downregulated expression of hsa-circ-0046600 significantly inhibited the migration of HepG2 and SK-HEP-1 cells. hsa-circ-0046600 is present mainly in the cytoplasm and promotes the expression of proteins such as HIF-1? by competitively binding to miR-640 in HCC, thereby affecting the malignant biological behaviour of liver cancer cells. Conclusion:hsa-circ-0046600 can be used as a new biomarker for HCC diagnosis and disease progression and provides a potential target for targeted therapy.
Project description:BACKGROUND:Circular RNA (circRNA) is a type of circular endogenous RNA produced by special selective splicing and participates in progression of diverse diseases. However, the role of circRNA in clear cell renal cell carcinoma (ccRCC) is still rarely reported. METHODS:We detected lower circ-AKT3 expression in ccRCC using the circular RNA microarray. Then, qPCR array was applied to verify the expression of circ-AKT3 in between 60 ccRCC tissues and adjacent normal tissues, as well as ccRCC cell lines and human normal kidney cell (HK-2). We investigated the function of circ-AKT3 in ccRCC in vitro and in vivo and detected underlying mechanisms by Western blotting, bioinformatic analysis, RNA pull-down assay and luciferase reporter assay. RESULTS:Circ-AKT3 was verified significantly downregulated in ccRCC. Knockdown of circ-AKT3 promoted ccRCC migration and invasion, while overexpression of circ-AKT3 suppressed ccRCC metastasis. Further, circ-AKT3/miR-296-3p/E-cadherin axis was shown responsible for circ-AKT3 inhibiting ccRCC metastasis. CONCLUSION:Circ-AKT3 suppresses ccRCC metastasis by enforcing E-cadherin expression through competitively binding miR-296-3p. Circ-AKT3 may therefore serve as a novel therapeutic to better suppress ccRCC metastasis.
Project description:BACKGROUND:Cancer metastasis is responsible for 90% of cancer-related deaths. Recently, circular RNA (circRNA) is deemed to be an important regulator of cancer progression. However, little is known about the role of circRNA in the metastasis of lung adenocarcinoma (LUAD). Herein, we investigated the clinical implication and regulatory effect of circ-TSPAN4 (hsa_circ_0020732) in LUAD. METHODS:Gene Expression Omnibus (GEO) database (GSE104854) was used to identify the aberrantly expressed circRNAs in LUAD. The expression levels of circ-TSPAN4, miR-4731-5p, miR-665, and ZEB1 were determined by quantitative reverse transcription PCR (qRT-PCR). The functional experiments were carried out with wound healing and transwell assays. And, the luciferase reporter and RNA pull-down assays were employed to examine the crosstalk between circ-TSPAN4, miR-665, and ZEB1. In vivo metastasis experiment was tested by the lung metastasis model. RESULTS:Circ-TSPAN4 was significantly upregulated in LUAD tissues and cell lines. The increased circ-TSPAN4 was linked to advanced tumor-node-metastasis stage, lymph node and distant metastasis, and poor outcome. Lentivirus-mediated stably circ-TSPAN4 knockdown dramatically attenuated the metastatic ability of LUAD cells both in vitro and in vivo. Mechanistically, circ-TSPAN4 directly interacted with miR-665, but not miR-4731-5p, to increase the expression of ZEB1, which is a well-known metastasis trigger. Importantly, the reduced metastatic capacity caused by circ-TSPAN4 depletion was partially rescued by miR-665 silencing or ZEB1 overexpression. CONCLUSIONS:Circ-TSPAN4 plays a pivotal metastasis-promoting role in LUAD through acting as a sponge for miR-665 and upregulating ZEB1.
Project description:Accumulating data indicated that circRNA plays important roles in regulating many biological processes of the tumor, the present study is designated for exploring roles of the circ-ZEB1.33-miR-200a-3p-CDK6 regulating axis in human hepatocellular carcinoma (HCC).The regulation axis as predicted by using online tool circNet, the expression and correlation of circ-ZEB1.33-miR-200a-3p-CDK6 was verified in human HCC. The diagnostic value of both tumor and serum circ-ZEB1.33 was estimated by using clinical samples. The roles of circ-ZEB1.33-miR-200a-3p-CDK6 in regulating cell cycle were explored by using in vitro studies.Overexpression of circ-ZEB1.33 and CDK6, downregulation of miR-200a-3p were detected in human HCC tissues, negative correlation between circ-ZEB1.33 and miR-200a-3p, positive correlation between circ-ZEB1.33 and CDK6 were confirmed in human HCC tissues. Tissue and serum circ-ZEB1.33 were related to different TMN stages and prognosis in HCC patients. RNA pull-down assay implied that circ-ZEB1.33 could decrease miR-200a-3p by sponging miR-200a-3p, and the luciferase reporter assay indicated that miR-200a-3p could downregulate CDK6 transcription by targeting its 3'UTR. The in vitro assays indicated that circ-ZEB1.33 could promote the proliferation of HCC cells by increasing the percentage of S phase regulated by CDK6/Rb.Proliferation promotion roles of the circ-ZEB1.33-miR-200a-3p-CDK6 regulating axis are existed and verified in human HCC, both tumor and serum circ-ZEB1.33 can serve as an indicator for the prognosis of HCC patients.
Project description:Background:Circular RNA (circRNA) has recently been considered as a key regulator in carcinogenesis. In this study, we investigated the functional significance and regulatory role of circ-CAMK2A (hsa_circ_0128332) in lung adenocarcinoma (LUAD). Methods:GSE101586 was employed to screen differentially expressed circRNAs. = Relative expression levels of circ-CAMK2A, miR-615-5p, fibronectin 1 (FN1), MMP2, and MMP9 were tested by quantitative reverse transcription PCR (qRT-PCR) or western blotting. Functional experiments were performed by CCK-8, wound healing, and transwell assays. Luciferase reporter and biotin-labeled RNA pull-down assays were carried out to evaluate the interaction between circ-CAMK2A, miR-615-5p, and fibronectin 1. In addition, a lung metastasis model was constructed to determine the metastasis-promoting role of circ-CAMK2A in vivo. Results:Circ-CAMK2A overexpression was observed in LUAD and was closely associated with lymph node metastasis, distant metastasis, advanced clinical stage, and poor prognosis. Circ-CAMK2A silencing evidently inhibited LUAD cell migration and invasion, whereas circ-CAMK2A overexpression had an opposite effect. Importantly, overexpression of circ-CAMK2A also enhanced LUAD metastasis in vivo. Mechanistically, miR-615-5p was identified as a direct target of circ-CAMK2A. Circ-CAMK2A up-regulates the expression level of fibronectin 1 by sponging miR-615-5p, thereby increasing MMP2 and MMP9 expression to promote the metastasis of LUAD. Conclusion:Circ-CAMK2A plays a crucial role in the metastasis of LUAD, at least partially, by regulating the miR-615-5p/fibronectin 1 axis.
Project description:BACKGROUND:Circular RNAs (circRNAs), a subclass of non-coding RNAs, play essential roles in tumorigenesis and aggressiveness. Our previous study has identified that circAGO2 drives gastric cancer progression through activating human antigen R (HuR), a protein stabilizing AU-rich element-containing mRNAs. However, the functions and underlying mechanisms of circRNAs derived from HuR in gastric cancer progression remain elusive. METHODS:CircRNAs derived from HuR were detected by real-time quantitative RT-PCR and validated by Sanger sequencing. Biotin-labeled RNA pull-down, mass spectrometry, RNA immunoprecipitation, RNA electrophoretic mobility shift, and in vitro binding assays were applied to identify proteins interacting with circRNA. Gene expression regulation was observed by chromatin immunoprecipitation, dual-luciferase assay, real-time quantitative RT-PCR, and western blot assays. Gain- and loss-of-function studies were performed to observe the impacts of circRNA and its protein partner on the growth, invasion, and metastasis of gastric cancer cells in vitro and in vivo. RESULTS:Circ-HuR (hsa_circ_0049027) was predominantly detected in the nucleus, and was down-regulated in gastric cancer tissues and cell lines. Ectopic expression of circ-HuR suppressed the growth, invasion, and metastasis of gastric cancer cells in vitro and in vivo. Mechanistically, circ-HuR interacted with CCHC-type zinc finger nucleic acid binding protein (CNBP), and subsequently restrained its binding to HuR promoter, resulting in down-regulation of HuR and repression of tumor progression. CONCLUSIONS:Circ-HuR serves as a tumor suppressor to inhibit CNBP-facilitated HuR expression and gastric cancer progression, indicating a potential therapeutic target for gastric cancer.
Project description:Circular RNA (circRNA) exerts an essential role in tumor development. Hsa_circ_0001649 (circ-0001649) was produced at the SHPRH gene locus containing exon 26-29. This study analyzed the specific mechanism of circ-0001649 in influencing the development of hepatocellular carcinoma (HCC). Relative levels of circ-0001649 in HCC cell lines and tissues were examined by qRT-PCR. The direct binding between circ-0001649 and miR-127-5p/miR-612/miR-4688 were verified through Dual-luciferase reporter gene assay, RNA Binding Protein Immunoprecipitation (RIP) assay and western blot detection. In vitro and in vivo regulatory roles of circ-0001649 in proliferative and migratory abilities of HCC were evaluated by EdU, Transwell and tumourigenicity assay, respectively. Results showed that circ-0001649 was markedly decreased in hepatocellular carcinoma cell lines and tumor tissues. Overexpression of circ-0001649 greatly inhibited proliferation and migration of HCC in vitro and in vivo. More importantly, we confirmed that circ-0001649 regulated cellular behaviors of HCC cells by targeting SHPRH. Furthermore, we determined that circ-0001649 served as a ceRNA to sponge miR-127-5p, miR-612 and miR-4688, thus activating SHPRH. In summary, our study showed that circ-0001649 was lowly expressed in HCC and inhibited HCC progression via multiple miRNAs sponge.
Project description:To analyze the diagnostic value of a circular RNA (circRNA), circ-LDLRAD3, in pancreatic cancer.Expression levels of circ-LDLRAD3 were tested in both cells and clinical samples; the latter included 30 paired pancreatic cancer tissues and adjacent non-tumorous tissues, 31 plasma samples from patients with pancreatic cancer, and 31 plasma samples from healthy volunteers. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to measure expression levels of circ-LDLRAD3 in cells and clinical samples; then, the relationship between clinicopathological factors of patient samples and expression of circ-LDLRAD3 in pancreatic cancer was analyzed. The diagnostic value of circ-LDLRAD3 was verified by receiver operating characteristic (ROC) curve analysis.Circ-LDLRAD3 was up-regulated in pancreatic cancer cell lines (P < 0.01), pancreatic cancer tissues (P < 0.01), and plasma samples from patients with pancreatic cancer (P < 0.01). High expression of circ-LDLRAD3 was significantly associated with venous invasion, lymphatic invasion, and metastasis. The area under the ROC curve of circ-LDLRAD3 alone or combination with CA19-9 was 0.67 and 0.87, respectively, with a sensitivity and specificity of 0.5738 (alone) and 0.7049 (alone), and 0.8033 (combination) and 0.9355 (combination), respectively.These data suggest that circ-LDLRAD3 may be a biomarker in the diagnosis of pancreatic cancer.
Project description:Circular RNAs (circRNAs) represent a class of covalently closed RNAs, derived from non-canonical splicing events, which are expressed in all eukaryotes and often conserved among different species. We previously showed that the circRNA originating from the ZNF609 locus (circ-ZNF609) acts as a crucial regulator of human primary myoblast growth: indeed, the downregulation of the circRNA, and not of its linear counterpart, strongly reduced the proliferation rate of in vitro cultured myoblasts. To deepen our knowledge about circ-ZNF609 role in cell cycle regulation, we studied its expression and function in rhabdomyosarcoma (RMS), a pediatric skeletal muscle malignancy. We found that circ-ZNF609 is upregulated in biopsies from the two major RMS subtypes, embryonal (ERMS) and alveolar (ARMS). Moreover, we discovered that in an ERMS-derived cell line circ-ZNF609 knock-down induced a specific block at the G1-S transition, a strong decrease of p-Akt protein level and an alteration of the pRb/Rb ratio. Regarding p-Akt, we were able to show that circ-ZNF609 acts by counteracting p-Akt proteasome-dependent degradation, thus working as a new regulator of cell proliferation-related pathways. As opposed to ERMS-derived cells, the circRNA depletion had no cell cycle effects in ARMS-derived cells. Since in these cells the p53 gene resulted downregulated, with a concomitant upregulation of its cell cycle-related target genes, we suggest that this could account for the lack of circ-ZNF609 effect in ARMS.