WITHDRAWN: Circular RNA hsa_circ_0001564 facilitates tumorigenesis of osteosarcoma via sponging miR-29c-3p

CircRNA_102272 Promotes Cisplatin-Resistance in Hepatocellular Carcinoma by Decreasing MiR-326 Targeting of RUNX2

Background

Hepatocellular carcinoma (HCC) is the leading cause of tumor-associated death in males and females worldwide. HCC is mostly diagnosed at advanced stages and the chemotherapeutic cisplatin is one of the major therapeutic options in the treatment of patients with treating advanced HCC. Despite several reports on HCC multidrug resistance, the underlying regulatory mechanisms are still unclear.

Methods

RT-PCR was performed to detect circRNA_102272, miR-326 and RUNX2 expression. The CCK8 assay was used to examine cell proliferation and cisplatin IC₅₀ values. The luciferase reporter assay was performed to verify complementary combinations between circRNA_102272 and miR-326 and between miR-326 and RUNX2.

Results

CircRNA_102272 expression was upregulated in HCC tissues and cells. CircRNA_102272 knockdown suppressed HCC cell proliferation and decreased cisplatin-resistance. In addition, circRNA_102272 facilitated HCC cisplatin-resistance by regulating the miR-326/RUNX2 axis.

Conclusion

CircRNA_102272 is significantly increased in HCC tissues and cells and promotes HCC cell proliferation and cisplatin-resistance. More importantly, circRNA acts as a ceRNA to suppress the expression and activity of miR-326, leading to the increase in RUNX2 expression. By elucidating circRNA_102272 role and mechanism of action in HCC, our study provides insights and an opportunity to overcome cisplatin-resistance in HCC.

Expression of circ_001569 is upregulated in osteosarcoma and promotes cell proliferation and cisplatin resistance by activating the Wnt/β-catenin signaling pathway

Circular RNAs (circRNAs), a type of non-coding RNAs derived from back-splicing, have been reported to function as gene expression regulators involved in tumor development of multiple human tumors. However, the clinical significance and underlying molecular mechanisms of circ_001569 in osteosarcoma still be unknown. In the study, we found that circ_001569 expression was significantly overexpressed in osteosarcoma tissues compared with adjacent noncancerous bone tissues. Higher circ_001569 expression significantly correlated with distant metastasis and advanced tumor stage of osteosarcoma patients. Gain-function and loss-function assays showed that circ_001569 knockdown significantly inhibited osteosarcoma cell proliferation and cell colon formation capacities. Moreover, upregulation of circ_001569 significantly promoted osteosarcoma cell resistance to cisplatin by activating Wnt/β-catenin signaling pathway. Thus, these results indicated that circ_001569 represented a novel potentially therapeutic target of osteosarcoma.

Deep RNA sequencing reveals the dynamic regulation of miRNA, lncRNAs, and mRNAs in osteosarcoma tumorigenesis and pulmonary metastasis

Osteosarcoma (OS) is the most common pediatric malignant bone tumor, and occurrence of pulmonary metastasis generally causes a rapid and fatal outcome. Here we aimed to provide clues for exploring the mechanism of tumorigenesis and pulmonary metastasis for OS by comprehensive analysis of microRNA (miRNA), long non-coding RNA (lncRNA), and mRNA expression in primary OS and OS pulmonary metastasis. In this study, deep sequencing with samples from primary OS (n = 3), pulmonary metastatic OS (n = 3), and normal controls (n = 3) was conducted and differentially expressed miRNAs (DEmiRNAs), lncRNAs (DElncRNAs), and mRNAs (DEmRNAs) between primary OS and normal controls as well as pulmonary metastatic and primary OS were identified. A total of 65 DEmiRNAs, 233 DElncRNAs, and 1405 DEmRNAs were obtained between primary OS and normal controls; 48 DEmiRNAs, 50 DElncRNAs, and 307 DEmRNAs were obtained between pulmonary metastatic and primary OS. Then, the target DEmRNAs and DElncRNAs regulated by the same DEmiRNAs were searched and the OS tumorigenesis-related and OS pulmonary metastasis-related competing endogenous RNA (ceRNA) networks were constructed, respectively. Based on these ceRNA networks and Venn diagram analysis, we obtained 3 DEmiRNAs, 15 DElncRNAs, and 100 DEmRNAs, and eight target pairs including miR-223-5p/(CLSTN2, AC009951.1, LINC01705, AC090673.1), miR-378b/(ALX4, IGSF3, SULF1), and miR-323b-3p/TGFBR3 were involved in both tumorigenesis and pulmonary metastasis of OS. The TGF-β superfamily co-receptor TGFBR3, which is regulated by miR-323b-3p, acts as a tumor suppressor in OS tumorigenesis and acts as a tumor promoter in pulmonary metastatic OS via activation of the epithelial-mesenchymal transition (EMT) program.In conclusion, the OS transcriptome (miRNA, lncRNA, and mRNA) is dynamically regulated. These analyses might provide new clues to uncover the molecular mechanisms and signaling networks that contribute to OS progression, toward patient-tailored and novel-targeted treatments.

Circular RNAs: a new frontier for cancer diagnosis and therapy

In recent years, circular RNAs (circRNAs) have attracted considerable attention because they play a significant role in many fields of cancer biology. Additionally, it has become increasingly clear that circRNAs have the potential to make contributions to the successful application of individualized cancer medicine. This brief review introduces circRNAs by describing their potential as a biomarker and therapeutic target and discussing the possible strategies to target them. This review also presents the challenges that are encountered by circRNAs for their definitive entry into clinical practice. Clearly, our understanding of circRNAs helps to add a new dimension to the molecular structure of cancer and will provide many new opportunities for cancer treatment.

Circular RNA: An emerging non-coding RNA as a regulator and biomarker in cancer

Circular RNA (circRNA) is a type of covalently closed non-coding RNA that may regulate gene expression in eukaryotes. The recent application of high-throughput RNA sequencing and bioinformatics approaches has revealed a large number of circRNAs in human cells. Emerging evidence indicates that many circRNAs have cell-type specific expression and are linked to physiological development and various diseases. Specially, circRNAs can either serve as oncogenic stimuli or tumor suppressors in cancer. circRNAs have also been shown to be enriched and stable in extracellular fluid, indicating the potential of circRNAs as cancer biomarkers. Here, we summarize the current knowledge of circRNAs, including their classification, biogenesis, properties, and databases, as well as their function and clinical implications in cancer.

Circular RNAs: Biogenesis, Function, and a Role as Possible Cancer Biomarkers

Circular RNAs (circRNAs) are a class of noncoding RNAs (ncRNAs) that form covalently closed continuous loop structures, lacking the terminal 5' and 3' ends. CircRNAs are generated in the process of back-splicing and can originate from different genomic regions. Their unique circular structure makes circRNAs more stable than linear RNAs. In addition, they also display insensitivity to ribonuclease activity. Generally, circRNAs function as microRNA (miRNA) sponges and have a regulatory role in transcription and translation. They may be also translated in a cap-independent manner in vivo, to generate specific proteins. In the last decade, next-generation sequencing techniques, especially RNA-seq, have revealed great abundance and also dysregulation of many circRNAs in various diseases, suggesting their involvement in disease development and progression. Regarding their high stability and relatively specific differential expression patterns in tissues and extracellular environment (e.g., body fluids), they are regarded as promising novel biomarkers in cancer. Therefore, we focus this review on describing circRNA biogenesis, function, and involvement in human cancer development and address the potential of circRNAs to be effectively used as novel cancer diagnostic and prognostic biomarkers.

Identification and comparison of novel circular RNAs with associated co-expression and competing endogenous RNA networks in pulmonary tuberculosis

Pulmonary tuberculosis (PTB) is caused by Mycobacterium tuberculosis and is one of the most serious diseases worldwide. Circular RNAs (circRNAs) are a large class of non-coding RNAs that were identified with potential regulatory roles in disease pathogenesis and progression. In this study, we used whole transcriptome sequencing to identify circRNAs from 3 PTB patients and 3 healthy individuals to determine the expression pattern of circRNAs in blood and the circRNA molecular regulatory networks in PTB pathogenesis. One hundred and seventy differentially expressed (≥ 2-fold change) circRNAs were dysregulated in PTB, compared with in healthy individuals. Quantitative real-time polymerase chain reaction was used to validate the RNA sequencing analysis from 20 PTB patients, and the results were consistent with the sequencing data. Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway analysis were applied to explore the potential circRNA functions of the significantly deregulated genes. Several immunity pathways, including endocytosis pathways in cancer, mitogen-activated protein kinase signaling pathway, human T-lymphotropic virus type 1 infection, and ubiquitin-mediated proteolysis, were involved in PTB pathogenesis. Competing endogenous RNAs (ceRNA) were constructed and inferred that aberrant expression of circRNA-associated ceRNA resulted in extensive variation in gene expression by miRNA-mediated circRNA-mRNA crosstalk interactions. Our study revealed that the circRNA-miRNA-mRNA network may shed light on the biological functions of circRNAs in PTB and provide useful information for exploring potential roles of circRNA in PTB.