Silencing Of Hsa Research Articles

Hsa_circ_0023642 promotes proliferation, invasion, and migration of gastric cancer by sponging microRNA-223.

BackgroundCircular RNAs (circRNAs) have a closed‐loop structure and are associated with various cellular biological processes, including carcinogenesis and cancer development. However, our knowledge of circRNAs in gastric cancer (GC) remains limited. Thus, this study aimed to investigate the role and underlying molecular mechanisms of hsa_circ_0023642 in GC.Materials and methodsBioinformatic analysis revealed that hsa_circ_0023642 was upregulated in GC. Chromogenic in situ hybridization (CISH) chips was used to explore the relationship between the expression of hsa_circ_0023642 and the malignant degree, clinical stage, and prognosis of patients with GC. The role of hsa_circ_0023642 in GC was assessed in vitro, and biotin‐coupled RNA pull‐down was conducted to evaluate the interaction in between hsa_circ_0023642 and miR‐223.ResultsThe current study showed that hsa_circ_0023642 was upregulated in GC and presented a high positive correlation with the malignant progression of GC. In addition, in vitro experiments showed that the silencing of hsa_circ_0023642 in GC cell lines MKN‐45 and SGC‐7901 significantly reduced the proliferation, invasion, and migration of GC cells. We confirmed that hsa_circ_0023642 could serve as a sponge of miR‐223, subsequently promoting GC progression.ConclusionThis study shows that the upregulation of hsa_circ_0023642 affects the malignant progression, clinical stage, and prognosis of GC which provides a new molecular target for the therapy of GC.

Silencing of hsa_circ_0101145 reverses the epithelial-mesenchymal transition in hepatocellular carcinoma via regulation of the miR-548c-3p/LAMC2 axis.

Hepatocellular carcinoma (HCC) is a primary cause of cancer-related deaths globally. While there have been advancements in HCC treatment and diagnosis, incidence and mortality rates continue to rise. One study found that circular RNAs functioned as competing endogenous RNAs, and constructed a gene-based nomogram to estimate overall survival of HCC patients. Previous studies using high-throughput sequencing suggested that hsa_circ_0101145 is abnormally expressed in HCC, but the underlying mechanism is unknown. We performed RT-qPCR to determine hsa_circ_0101145 and miR-548c-3p expression in HCC tissues. We used fluorescence in situ hybridization (FISH) to detect hsa_circ_0101145 expression and hsa_circ_0101145 subcellular localization in HCC tissues. hsa_circ_0101145 expression in HCC cells was selectively regulated. We determined LAMC2 and EMT mRNA and protein levels by RT-qPCR and western blotting analysis, respectively. We employed flow cytometry, and CCK8, Transwell, and wound healing assays to monitor the cell cycle, cell proliferation, invasion, and migration, respectively. We employed dual-luciferase reporter and RNA pulldown assays to verify the relationship among hsa_circ_0101145, miR-548c-3p, and LAMC2. We examined the effects of hsa_circ_0101145 on HCC cell metastasis and proliferation in vivo using a subcutaneous xenograft model as well as intravenous tail injection of nude mice. The data demonstrated that hsa_circ_0101145 was significantly upregulated in both HCC tissues and cell lines. High hsa_circ_0101145 expression was correlated with aggressive HCC phenotypes. Downregulation of hsa_circ_0101145 suppressed HCC proliferation as well as metastasis by targeting the miR-548c-3p/LAMC2 axis, which was examined using luciferase reporter and RNA pulldown assays. Silencing of hsa_circ_0101145 suppressed the epithelial-mesenchymal transition in HCC. Downregulation of miR-548c-3p or overexpression of LAMC2 restored migration and proliferation abilities of HCC cells following hsa_circ_0101145 silencing. LAMC2 overexpression reversed miR-548c-3p-induced cell migration and growth inhibition in vitro. In summary, the findings illustrated that hsa_circ_0101145 silencing suppressed HCC progression by functioning as an miR-548c-3p sponge to enhance LAMC2 expression. Therefore, hsa_circ_0101145 could be an HCC treatment target.

Implication of hsa_circ_0028007 in reinforcing migration, invasion, and chemo-tolerance of nasopharyngeal carcinoma cells.

BackgroundGiven the reliability of circRNAs in symbolizing cancer progression, this investigation was designed to expound the involvement of hsa_circ_0028007 in regulating chemosensitivity of nasopharyngeal carcinoma (NPC) cells.MethodsAltogether, 241 pairs of NPC tissues and para‐cancerous normal tissues were collected to identify NPC‐symbolic circRNAs, which have been screened by circRNA microarray in advance. Expressions of the circRNAs were determined by means of real‐time polymerase chain reaction (PCR). Besides, human NPC cell lines (ie, CNE2 and HONE1) were transfected by si‐hsa_circ_0028007 and si‐NC. Scratch assay, transwell assay, and MTT assay were performed to assess migration, invasion, and paclitaxel/cisplatin‐resistance of NPC cell lines.ResultsHsa_circ_0028007 expression was abnormally heightened within NPC tissues in comparison with matched non‐tumor tissues (P < .05). Over‐expressed hsa_circ_0028007 was strongly associated with advanced (III‐IV) tumor stage, aggressive infiltration, and metastatic lymph nodes of NPC patients (P < .05). Regarding in vitro experiments, hsa_circ_0028007 expression was elevated in CNE2 and HONE1 cell lines as compared with HENE cell line (P < .05). Silencing of hsa_circ_0028007 not merely sensitized CNE2 and HONE1 cells against paclitaxel and cisplatin (P < .05), but also significantly repressed migration and invasion of the cell lines (P < .05).ConclusionHsa_circ_0028007 was involved in facilitating progression and chemo‐resistance of NPC, which might offer an alternative for NPC treatment.

Caffeic acid phenethyl ester against cadmium induced toxicity mediated by CircRNA modulates autophagy in HepG2 cells.

Cadmium pollution and poisoning are serious environmental and pharmacological concerns, and effective drugs can alleviate or offset cadmium-induced toxicity are badly needed. In this study, Caffeic acid phenethyl ester (CAPE), a major active component of propolis, showed protective effect against CdCl2-induced toxicology by suppressing autophagy in HepG2 cells. CircRNAs are increasingly perceived as vital regulators in the process of autophagy. However, it remain unclear whether circRNAs are involved in CAPE's protection against CdCl2-induced autophagy. Under this context, the roles of CircRNA (hsa_circ_0040768) in CAPE's protection against CdCl2-induced damage were investigated by PCR and Western blot. Results showed that CAPE significantly (P<0.05) increased cell viability via inhibiting CdCl2-induced autophagy, and this process was regulated by hsa_circ_0040768/MAP1LC3B axis. Overexpressing hsa_circ_0040768 led to reduced cell viability and increased autophagy in CAPE-treated HepG2 cells exposed to CdCl2. In contrast, silencing hsa_circ_0040768 showed similar protective effect to CAPE. These results show for the first time the involvement of the hsa_circ_0040768/MAP1LC3B axis in the CAPE's protection against CdCl2-induced autophagy, and provide novel insights into the pathogenesis and potential prevention/treatment of cadmium-associated diseases.

Circular RNA-Expression Profiling Reveals a Potential Role of Hsa_circ_0097435 in Heart Failure via Sponging Multiple MicroRNAs.

Circular RNAs represent a new type of non-coding RNA molecules that influence the occurrence and development of various human diseases by sponging microRNAs, although their roles in heart failure have not been clarified. In this study, peripheral blood samples from 5 patients with heart failure and 4 healthy volunteers were analyzed by next-generation sequencing (NGS) to screen for differentially expressed Circular RNAs. Fifty-six differentially expressed Circular RNAs were identified, of which 29 were up-regulated and 27 were down-regulated. Dysregulated expression of 6 Circular RNAs was verified by quantitative polymerase chain reaction (PCR) analysis, and hsa_circ_0097435 expression was confirmed to be significantly up-regulated in 40 patients with heart failure. Further study with extracted exosomes showed that hsa_circ_0097435 expression was significantly higher in patients with heart failure. In cardiomyocytes, hsa_circ_0097435 was up-regulated after doxorubicin treatment, promoting cardiomyocyte apoptosis. Hsa_circ_0097435 overexpression promoted cardiomyocyte apoptosis, and silencing hsa_circ_0097435 inhibited apoptosis. Moreover, RNA-pulldown experiments and AGO2-immunoprecipitation experiments revealed that hsa_circ_0097435 potentially served a role in heart failure by sponging multiple microRNAs. Collectively, these results suggest that hsa_circ_0097435 can be used as a biological blood marker and revealed a new pathway involved in regulating myocardial cell injury. Our findings may provide a rational basis for developing new treatments for heart failure.

Hsa_circ_0000092 promotes hepatocellular carcinoma progression through up-regulating HN1 expression by binding to microRNA-338-3p.

Circular RNAs (circRNAs) have been identified in diverse cancers for their role in regulating multiple cellular processes by antagonizing microRNAs (miRNAs or miRs). However, the role of circRNA hsa_circ_0000092 in hepatocellular carcinoma (HCC) still remains enigmatic. Therefore, we aimed to investigate the specific mechanism of hsa_circ_0000092 in HCC. Differentially expressed circRNAs associated to HCC were initially analysed. The expression of hsa_circ_0000092, miR-338-3p and HN1 in HCC tissues and cell lines was examined. Next, the interaction among hsa_circ_0000092, miR-338-3p and HN1 was determined by dual-luciferase reporter, RNA pull-down and northern blot assays. Subsequently, a series of mimic, inhibitor or siRNA plasmids were delivered into HCC cells to validate the effects of hsa_circ_0000092, miR-338-3p and HN1 in controlling cell proliferation, migration, invasion and angiogenesis in vitro. Furthermore, the role of hsa_circ_0000092 in tumour growth of HCC in vivo was assessed with hsa_circ_0000092 depleted with siRNA. The hsa_circ_0000092/miR-338-3p/HN1 axis was predicted to participate in the development of HCC. hsa_circ_0000092 and HN1 were highly expressed while miR-338-3p was poorly expressed in HCC tissues and cell lines. hsa_circ_0000092 could competitively bind to miR-338-3p to up-regulate HN1 expression. Moreover, depleted hsa_circ_0000092 or elevated miR-338-3p was shown to suppress HCC cell proliferation, migration, invasion and angiogenesis in vitro via down-regulation of HN1. Furthermore,silencing hsa_circ_0000092 was demonstrated to suppress tumour growth in HCC in vivo. The results of this study suggested that hsa_circ_0000092 impaired miR-338-3p-mediated HN1 inhibition to aggravate the development of HCC, indicating that hsa_circ_0000092 is a potential candidate marker and therapeutic target for HCC.

Circular RNA hsa_circ_0056836 functions an oncogenic gene in hepatocellular carcinoma through modulating miR-766-3p/FOSL2 axis.

Background: Circular RNA (circRNA) remains a tumour-related factor in various biological cells and plays regulatory roles in gene expression. It is a type of non-coding RNA, whereas the function of human circRNA in hepatocellular carcinoma (HCC) is still not clear yet. Our investigation used the HCC cell line to uncover the biological function of hsa_circ_0056836 in the development and progression of hepatocellular carcinoma.Results: The present study showed that hsa_circ_0056836 revealed high expressions in HCC cell lines and tissues compared with corresponding controls. Silencing of Hsa_circ_0056836 decreased cell migration, proliferation and invasion. Silencing of hsa_circ_0056836 inhibited the development of HCC in xenograft nude mice. Mechanistically, we found that hsa_circ_0056836 directly bound to miR-766-3p, thereby alleviating the targeted inhibition of Fos-related antigen 2 (FOSL2). The results of this study indicated that hsa_circ_0056836 is a novel oncogenic RNA of vast potential as a tumor biomarker.Conclusion: In summary, the hsa_circ_0056836 / miR-766-3p / FOSL2 axis may serve as a promising strategy for HCC treatment.Method: First, the expressions of hsa_circ_0056836 in HCC tissues and corresponding para-cancerous tissues as well as in HCC cell lines and normal hepatocytes THLE-3 were detected by RT-PCR. Subcellular localization of hsa_circ_0056836 was confirmed by FISH. To detect the association between hsa_circ_0056836 and miR-766-3p, AGO2-RIP and Luciferase reporter assay were adopted. Loss of function study was applied to assess the role of hsa_circ_0056836 in HCC and to determine tumorigenesis in nude mice.

Circular RNA hsa_circRNA_002178 silencing retards breast cancer progression via microRNA-328-3p-mediated inhibition of COL1A1.

Circular RNAs (circRNAs) are a group of non‐coding RNAs implicated in the pathogenesis of cancer progression, which exert their functions via regulation of microRNAs (miRNAs) and genes. The present study uses gain‐ and loss‐of‐function approaches to evaluate the functions of hsa_circRNA_002178 in angiogenesis along with energy metabolism and underlying downstream signals. The expression pattern of hsa_circRNA_002178 in clinical breast cancer tissues and its association with prognosis were characterized at first. Next, the energy metabolism and angiogenesis as well as cell viability were evaluated when the expression of hsa_circRNA_002178 in breast cancer cells was knocked down by siRNA. The interaction between hsa_circRNA_002178 and its downstream miR‐328‐3p was identified, followed by the analysis of their functions in regulation of breast cancer cellular behaviours. The target gene of miR‐328‐3p was predicted and verified, followed by identifying its role in the breast cancer progression. Higher expression of hsa_circRNA_002178 shared an association with worse prognosis in breast cancer. The inhibition of hsa_circRNA_002178 resulted in reductions in cell viability, energy metabolism and tube formation ability. Hsa_circRNA_002178 could competitively bind to miR‐328‐3p and down‐regulated its expression. Restoration of miR‐328‐3p eliminated the tumour‐promoting effects of hsa_circRNA_002178. COL1A1, as a target of miR‐328‐3p, could be up‐regulated by overexpression of hsa_circRNA_002178. In vivo experiments further confirmed the inhibition of tumour growth and inflammation by silencing hsa_circRNA_002178 or up‐regulating miR‐328‐3p. Taken together, hsa_circRNA_002178 is highlighted as a promising target for breast cancer due to the anti‐tumour effects achieved by silencing hsa_circRNA_002178.

RETRACTED: hsa_circ_001653 Implicates in the Development of Pancreatic Ductal Adenocarcinoma by Regulating MicroRNA-377-Mediated HOXC6 Axis

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive pancreatic cancer with poor survival rate. Circular RNAs (circRNAs) signatures have been identified in some human cancers, but there are little data concerning their presence in PDAC. We investigated the role of hsa_circ_001653, a newly identified circRNA, in the development of PDAC. hsa-circ-001653 expression was measured in 83 paired normal and tumor tissues surgically resected from PDAC patients. Phenotypic changes of PDAC cells were evaluated by assays for cell viability, cell cycle, invasion, and apoptosis. Tube-like structure formation of human umbilical vein endothelial cells (HUVECs) was examined in the presence of PDAC cells. Cross-talk between hsa_circ_001653 and microRNA-377 (miR-377)/human homeobox C6 (HOXC6) was assessed using dual-luciferase reporter assay, Ago2 immunoprecipitation, and northern blot analysis. Nude mice were inoculated with human PDAC cells for in vivo analysis. hsa_circ_001653 was an upregulated circRNA in PDAC. Silencing of hsa_circ_001653 in PDAC cells via RNA interference inhibited cell viability, cell-cycle progression, in vitro angiogenesis, and invasive properties, showing a pro-apoptotic effect. hsa_circ_001653 was found to bind to miR-377, which in turn repressed HOXC6 expression. Inhibition of miR-377 by its specific inhibitor restored cell viability, cell-cycle progression, in vitro angiogenesis, and invasive properties in PDAC cells lacking endogenous hsa_circ_001653. When nude mice were inoculated with human PDAC cells, inhibition of hsa_circ_001653 had a therapeutic effect. Collectively, the present study provides an enhanced understanding of hsa_circ_001653 as a therapeutic target for PDAC.

Circular RNA hsa_circ_001895 serves as a sponge of microRNA-296-5p to promote clear cell renalcell carcinoma progression by regulating SOX12.

There is an urgent need to find novel potential therapeutic targets for the diagnosis and treatment of clear cell renal cell carcinoma (ccRCC) due to its highly invasive ability as a common urological malignant tumor. Circular RNAs (circRNAs) have been indicated as potentially critical mediators in various types of tumor progression. We first used qRT‐PCR analysis to find dysregulated circRNAs in ccRCC. A novel circRNA, hsa_circ_001895, was upregulated in ccRCC specimens and associated with metastatic properties of ccRCC. However, the tumorigenic mechanism of hsa_circ_001895 on ccRCC is yet to be found. We first indicated that hsa_circ_001895 predicted a poor prognosis in ccRCC patients. Additionally, overexpression of hsa_circ_001895 not only promoted cell proliferation, invasion and migration of ccRCC, but also inhibited cell apoptosis, whereas hsa_circ_001895 knockdown reversed the effect on ccRCC progression. In vivo s.c. xenotransplanted tumor model also showed that silencing hsa_circ_001895 could suppress in vivo ccRCC growth. Mechanistically, hsa_circ_001895 directly binds with microRNA (miR)‐296‐5p and inhibits its expression. Moreover, sex determining region Y (SRY)‐box 12 (SOX12) was identified as a target of miR‐296‐5p, the expression of which was suppressed by miR‐296‐5p. Notably, the inhibitory effect of hsa_circ_001895 on ccRCC progression was reversed by miR‐296‐5p inhibitor. In general, our findings indicated that hsa_circ_001895 may sponge miR‐296‐5p and promote SOX12 expression, which is the underlying mechanism of hsa_circ_001895‐induced ccRCC progression.

RETRACTED ARTICLE: Silencing hsa_circ_PVT1 (circPVT1) suppresses the growth and metastasis of glioblastoma multiforme cells by up-regulation of miR-199a-5p

We, the Editors and Publisher of the journal Artificial Cells, Nanomedicine, and Biotechnology, have retracted the following article: Guonan Chi, Fuwei Yang, Donghui Xu & Weiming Liu (2020) Silencing hsa_circ_PVT1 (circPVT1) suppresses the growth and metastasis of glioblastoma multiforme cells by up-regulation of miR-199a-5p. Artificial Cells, Nanomedicine, and Biotechnology, 48:1, 188–196, DOI: 10.1080/21691401.2019.1699825 Since publication, concerns have been raised about the integrity of the data in the article. We reached out to the authors requesting that they supply information that would confirm the article’s integrity. The authors provided several files in response to our queries, but they were unable to provide the original data in a format which satisfies our requirements to confirm the authenticity of some types of data. In particular, they were unable to provide full western blots, where the molecular weight markers are indicated. In addition, the authors did not have a record of the full blot, before cutting it into strips. When checking their data the authors also confirmed there are fundamental errors present. Therefore, they have agreed to the retraction of this article. We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.

Circular RNA hsa_circ_0000515 acts as a miR-326 sponge to promote cervical cancer progression through up-regulation of ELK1.

This study investigates the role of circular RNA (circRNA) hsa_circ_0000515 in cervical cancer and the underlying mechanism associated with microRNA-326 (miR-326). hsa_circ_0000515 and ETS transcription factor ELK1 (ELK1) were initially over-expressed and miR-326 was down-regulated in cervical cancer tissues and cells. Low hsa_circ_0000515 expression was found to be associated with favorable prognosis of patients with cervical cancer. A series of mimics, inhibitors, over-expression plasmids or siRNAs were introduced into cervical cancer cells to alter the expression of hsa_circ_0000515, miR-326 and ELK1. In vitro experiments exhibited that silencing of hsa_circ_0000515 or upregulation of miR-326 resulted in suppressed proliferation and invasion, along with induced apoptosis and autophagy of cervical cancer cells. Dual-luciferase reporter assay, RNA pull-down and RIP assays highlighted that hsa_circ_0000515 was able to act as a ceRNA of miR-326 to increase ELK1. Furthermore, enhancement of ELK1 expression resulted in enhanced proliferation and invasion but repressed apoptosis and autophagy of cervical cancer cells. In vivo experiments further confirmed the suppressed tumor growth by hsa_circ_0000515 silencing. Our findings demonstrated that hsa_circ_0000515 acts as a tumor promoter in cervical cancer. The study provides evidence for targeting hsa_circ_0000515 for therapeutic purposes in treating cervical cancer.

Silencing hsa_Circ_0007478 Regulates EFNA3 Expression to Alleviate the ox-LDL-Induced Inflammatory Response by Sponging miR-765 in Macrophages

Background: Circular RNAs (circRNA), a novel class of RNAs, are a group of nonprotein-encoding RNA molecules capable of regulating mRNA expression at the posttranscriptional level. Rapidly growing evidence presented that some circRNAs are responsible for cardiovascular disease by playing a role as ceRNAs. However, little is known about circRNA the function of circRNAs in atherosclerosis(AS). Methods: Gene Expression Omnibus (GEO) database was applied to screen differentially expressed circRNAs of the normal macrophage group and the ox-LDL-stimulated group. CircInteractome, TargetScan and miRecords websites were used to predict target relationships. Findings: We found that hsa_circ_0007478 was upregulated in ox-LDL-stimulated macrophages, and compared with the ox-LDL-stimulated macrophage group, the protein level of NLRP3 and IL-1I² in macrophages was decreased and the activation of NF-IoB was inhibited in si-hsa_circ_0007478 group. Hsa_circ_0007478 has a base-pairing relationship with miR-765 through bioinformatics analysis. Furthermore, by modulating the hsa_circ_0007478 and the miR-765 level, it was indicated that hsa_circ_0007478 regulate EFNA3 expression to alleviate ox-LDL Induced inflammatory response by sponging miR765 in macrophages. Interpretation: This result indicates that the suppression of the hsa_circ_0007478/miR-765/EFNA3 axis alleviates inflammatory responses in ox-LDL-stimulated macrophages. Considering that hsa_circ_0007478 has a stable and conservative structure, our results provide a molecular basis and potential therapeutic target for relieving atherosclerotic progression. Funding: This study was supported by the National Natural Science Foundation of China (Grant No. 81670227 and 81600341) and the Wenzhou Science and Technology Bureau (Grant No. Y20170045 and Y20180099). Declaration of Interest: There is none of any conflict of interest, financial or otherwise, related to the submitted work. Ethical Approval: Not required.

High-throughput sequencing reveals circular RNA hsa_circ_0000592 as a novel player in the carcinogenesis of gastric carcinoma.

Background/Aim: Gastric cancer is one of the most common malignant tumors, and its complex pathogenesis has not been fully elucidated. Circular RNAs (circRNAs) are involved in various biological processes and human diseases. However, their exact functional roles and mechanisms of action remain largely unclear. We previously discovered the differential expression of non-coding RNAs (ncRNAs) during the malignant transformation of human gastric epithelial cells. In this study, we investigated the functional roles of a significantly up-regulated circRNA (hsa_circ_0000592) in gastric cancer. Methods: N-methyl-N′-nitro-N-nitrosoguanidine (MNNG)-induced malignant-transformed gastric epithelial cells (GES-1-T) and normal gastric epithelial cells (GES-1-N) were analyzed by high-throughput circRNA sequencing. The top 15 up-regulated circRNAs in high-throughput sequencing results were further confirmed by qRT-PCR in different gastric epithelial cell lines. The function of the most significant circRNA (hsa_circ_0000592) was investigated by using RNA interference (RNAi) assays, fluorescence in situ hybridization analysis (FISH), and bioinformatics prediction methods. Results: A total of 1509 genes were up-regulated and 3142 genes were down-regulated in GES-1-T cells when compared with GES-1-N cells. When compared with GES-1-N cells, hsa_circ_0000592 was obviously up-regulated in GES-1-T cells, as well as in other gastric cancer cell lines. The silencing of hsa_circ_0000592 mRNA led to a decrease in cell proliferation, cell cycle arrest at the G0/G1 phase, an increased rate of apoptosis, and a reduction in cell migration. Furthermore, FISH showed that hsa_circ_0000592 was mainly located in the cytoplasm, and a bioinformatics analysis suggested that hsa_circ_0000592 might function by sponging multiple miRNAs, and most notably four conserved miRNAs, including miR-139-3p, miR-200, miR-367-3p, and miR-33a-3p. Conclusion: This study is the first to identify hsa_circ_0000592 as a novel circRNA with a critical role in MNNG-induced gastric cancer. Due to the essential role of hsa_circ_0000592 in gastric carcinoma cells, it may be considered as a potential biomarker for use in diagnosing gastric carcinoma. Our findings provide a new insight into the function of circRNAs in environmental carcinogen-induced gastric cancer.

Circular RNA hsa_circ_0007142 Is Upregulated and Targets miR-103a-2-5p in Colorectal Cancer.

Circular RNAs (circRNAs) are a large class of endogenous noncoding RNAs that regulate gene expression and mainly function as microRNA sponges. This study aimed to explore the aberrant expression of circRNAs in colorectal cancer (CRC). Using a circRNA microarray, we identified 892 differentially expressed circRNAs between six pairs of CRC and adjacent paracancerous tissues. Among them, hsa_circ_0007142 was significantly upregulated. Further analysis in 50 CRC clinical samples revealed that hsa_circ_0007142 upregulation was associated with poor differentiation and lymphatic metastasis of CRC. Bioinformatic analysis and luciferase reporter assay showed that hsa_circ_0007142 targeted miR-103a-2-5p in CRC cells. Moreover, the silencing of hsa_circ_0007142 by siRNAs decreased the proliferation, migration, and invasion of HT-29 and HCT-116 cells. Taken together, these findings suggest that hsa_circ_0007142 is upregulated in CRC and targets miR-103a-2-5p to promote CRC.

Silencing of hsa_circ_0004771 inhibits proliferation and induces apoptosis in breast cancer through activation of miR-653 by targeting ZEB2 signaling pathway.

Background: Circular RNAs (circRNAs) have been reported as the competing endogenous RNAs (ceRNAs) to sponge microRNAs (miRNAs) implicating in the initiation and progression of breast cancer. However, the functions of circRNAs in breast cancer have not been completely clarified. In the present study, we aimed to identify differentially expressed circRNAs in breast cancer tumor tissues, and their roles and downstream targets were investigated in the progression of breast cancer. Methods: High-throughput circRNA sequencing was performed to detect the differentially expressed circRNAs. The CCK-8 and flow cytometry were performed to measure the cell viability and apoptosis in breast cancer cells. Gene and protein expression were assayed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting, respectively. Results: hsa_circ_0004771 and Zinc finger E-box binding homeobox 2 (ZEB2) expression levels were up-regulated and positively correlated in breast cancer tumor tissues. In addition, the expression levels of miR-653 were reduced in breast cancer tumor tissues. We also found that hsa_circ_0004771 functioned as a sponge of miR-653 to inhibit its expression. miR-653 as a post-transcriptional regulator down-regulated the expression of ZEB2 by binding to its 3′-UTR. Interestingly, a significant inverse correlation was observed between miR-653 and hsa_circ_0004771 or ZEB2 expression in breast cancer tumor tissues. Knockdown of hsa_circ_0004771 and ZEB2 served as equally authentic of miR-653 mimics to induce growth inhibition and apoptosis in breast cancer cells. Conclusion: Hsa_circ_0004771/miR-653/ZEB2 regulatory feedback revealed a new molecular mechanism in the pathogenesis of breast cancer, which might provide novel therapeutic targets for the treatment of breast cancer.

Circular RNA (hsa_circ_0051240) promotes cell proliferation, migration and invasion in ovarian cancer through miR-637/KLK4 axis

In this study, we identified hsa_circ_0051240 was significantly increased in ovarian cancer (OC) tissues. Our results indicated that silencing of hsa_circ_0051240 inhibited OC cell proliferation, migration and invasion in vitro, and also prevented OC tumour formation in vivo. In addition, the inhibitory effects by blockage of hsa_circ_0051240 could be attenuated by the miR-637 inhibitor. Furthermore, we also identified that hsa_circ_0051240 act as a sponge of miR-637, and miR-637 directly targeted KLK4 mRNA in OC cells. Altogether, hsa_circ_0051240 promotes OC cell proliferation, migration and invasion through inhibiting the miR-637/KLK4 axis. Therefore, these results demonstrated that the hsa_circ_0051240/miR-637/KLK4 axis might serve as a therapeutic target for OC treatment.

Hsa_circ_101280 promotes hepatocellular carcinoma by regulating miR-375/JAK2.

In this study, we sought to predict the effects of a certain circular RNA (circRNA), hsa_circ_101280 (also known as hsa_circ_0100929 and hsa_circ_SLAIN1), on hepatocellular carcinoma (HCC) cells and to determine the potential mechanism. After screening differentially expressed circRNAs in HCC tissues through Gene Expression Omnibus data analysis, hsa_circ_101280 was found to be highly expressed, and its high expression was verified in HCC cell lines with qRT-PCR along with the low expression of its downstream miRNA miR-375. Colony formation and flow cytometry assays showed that both hsa_circ_101280 silencing and miR-375 overexpression restrained proliferation and promoted apoptosis in HCC cells. JAK2 was identified as a downstream mRNA target of miR-375 by RNA pull-down and dual-luciferase reporter gene assays, its expression in HCC cell lines were positively regulated by hsa_circ_101280 and negatively by miR-375 expression. Furthermore, the silencing of hsa_circ_101280 significantly inhibited the growth of HCC xenografts in nude mice, with the downregulated expression of JAK2. Overall, both the invitro and invivo studies revealed that hsa_circ_101280 largely facilitated the tumorigenesis of HCC, characterized by the promoted proliferation and suppressed apoptosis of HCC cells, by sponging miR-375 and upregulating JAK2.

Circular RNA-100290 promotes cell proliferation and inhibits apoptosis in acute myeloid leukemia cells via sponging miR-203

Circular RNA (CirRNA) is a type of noncoding RNA that has been shown to play a unique role in tumor development and other fields in recent years. In this study, we aimed to explore the biological role of hsa_circ_100290 in acute myeloid leukemia (AML). First, we found that the expression of hsa_circ_100290 was increased in human AML samples and cell lines. Down-regulation of hsa_circ_100290 significantly suppressed cell proliferation of AML cells. Silencing hsa_circ_100290 also dramatically induced cell cycle arrest and apoptosis. Bioinformatic prediction and luciferase assay revealed that hsa_circ_100290 and Rab10 were targeted by miR-203. Validation experiments verified that hsa_circ_100290 was co-expressed with Rab10 and was negatively correlated with miR-203 expression. Moreover, rescue experiments demonstrated that miR-203 inhibitor could reverse the role of hsa_circ_100290 knockdown on proliferation and apoptosis in AML cells. Overall, the present study identifies the crucial regulation of hsa_circ_100290 in AML cell proliferation and apoptosis via targeting the miR-203/Rab10 axis.

Novel circular RNA, hsa_circ_0025039 promotes cell growth, invasion and glucose metabolism in malignant melanoma via the miR-198/CDK4 axis.

Malignant melanoma, a tumor derived from melanocytes, shows severe drug resistance and prompt metastasis, causing a serious threat to human health. Circular RNAs (circRNAs) are widely expressed in mammals and have been indicated to play important roles in tumorigenesis. In the present study, we analyzed the variability of circRNAs in malignant melanoma by microarray and identified six differentially expressed circRNAs. In particular, we found that hsa_circ_0025039, which is formed by FOXM1 exons, is significantly upregulated in melanoma. In vitro, the knockdown of circ_0025039 inhibited cell proliferation, colony formation ability, invasion and glucose metabolism in melanoma cells. Additionally, we identified miR-198 as a direct target of hsa_circ_0025039. Furthermore, we demonstrated that hsa_circ_0025039 regulates CDK4 expression by sponging miR-198. In vivo study indicated that the silencing of hsa_circ_0025039 inhibits melanoma tumor formation and downregulates miR-198 and CDK4 expression. Taken together, our data showed that circ_0025039 promotes cell growth, invasion and glucose metabolism in malignant melanoma by sponging miR-198 and regulating CDK4.