Project description:Circular RNAs (circRNAs), a noncoding RNA class originating from alternative splicing, are highly abundant in neural tissues and were shown to regulate gene expression e.g. by interacting with microRNAs and RNA-binding proteins. Neuroblastoma is an embryonal neoplasia, which arises from undifferentiated neural crest cells. Here, we aimed to explore, whether circRNAs influence the pathogenesis of high-risk neuroblastoma. We performed whole-transcriptome sequencing of 104 primary neuroblastoma samples of all risk-groups and identified 5,203 unique circRNAs involving 2,302 genes. Candidate circRNA expression did not correlate with host gene expression, indicating independent regulatory mechanisms. circRNAs were significantly downregulated in the MYCN-amplified high-risk tumors. These findings were independently reproduced in a tetracycline-inducible MYCN-overexpression system based on a non MYCN-amplified neuroblastoma cell line, suggesting that MYCN drives this global circRNA repression. We identified the RNA helicase DHX9 as a mediator of this global suppressive effect of MYCN on circRNAs. Comparing our RNA sequencing data with other cancers and controls revealed a circRNA subset specifically upregulated in neuroblastoma that included a circRNA derived from the ARID1A tumor suppressor gene. Specific circARID1A knockdown resulted in reduced proliferation, cell numbers and viability, prompted apoptosis and induced a differentiated phenotype. Neither knockdown, nor overexpression of circARID1A influenced ARID1A mRNA and protein levels significantly. To dissect the potential mode of function, we performed a pulldown assay with subsequent mass spectrometry. We identified the RNA-binding protein KHSRP as an interaction partner that participates in the mechanism of action of circARID1A. In summary, this study highlights an important role of circRNAs in neuroblastoma biology and may establish this RNA class as a future therapeutic target and biomarker.
Project description:Arraystar Human circRNA Microarray is designed for the global profiling of human circRNAs. In this study, we applied a circRNA microarray to screen the potential biomarker for HCC. 20 samples extracted from plasma samples including HCC group before operation, and after operation, CH group and control group. Each group contained five samples.
Project description:Circular RNAs (circRNAs) are covalently closed non-coding RNAs lacking the 5’ cap and the poly-A tail. Nevertheless, it has been demonstrated that certain circRNAs can undergo active translation. Therefore, aberrantly expressed circRNAs in human cancers could be an unexplored source of tumor-specific antigens, potentially mediating anti-tumor T cell responses. This study presents an immunopeptidomics workflow with a specific focus on generating a circRNA-specific protein fasta reference. The main goal of this workflow is to streamline the process of identifying and validating human leukocyte antigen (HLA) bound peptides potentially originating from circRNAs. We increased the analytical stringency of our workflow by retaining peptides identified independently by two mass spectrometry search engines and/or by applying a group-specific FDR for canonical-derived and circRNA-derived peptides. A subset of circRNA-derived peptides specifically encoded by the region spanning the back-splice junction (BSJ) were validated with targeted MS, and with direct Sanger sequencing of the respective source transcripts. Our workflow identified 54 unique BSJ-spanning circRNA-derived peptides in the immunopeptidome of melanoma and lung cancer samples. Our novel approach enlarges the catalog of source proteins that can be explored for immunotherapy.
Project description:Objective Circular RNAs (circRNAs) are covalently closed, endogenous non-coding RNAs. CircRNAs play a vital role in liver diseases, acting as microRNA (miRNA) sponges. However, the angiogenic role of circRNA remains unknown in liver fibrosis and is the focus of this study. Methods Liver fibrosis was induced by thioacetamide (TAA), or carbon tetrachloride (CCl4) in mice. CircRNA-microarray, AGO2-RNA immunoprecipitation (RIP), and RNA-seq were utilized to explore the hepatic circRNAs profile. The qPCR and PCR-gel electrophoresis analysis were used to investigate the characterization of circRNA-007371. Liver tissues and EMOA murine endothelial cells were used to verify the angiogenic mechanism of circRNA-007371. Results The increased collagen deposition, pseudolobule formation, and angiogenesis were observed in murine liver induced by TAA and CCl4. CircRNA-microarray in TAA-induced fibrotic murine liver indicated that the expression of circRNA-007371 was up-regulated. Moreover, AGO2-RIP and PCR analysis showed that circRNA-007371 had the characterization of circRNAs and played a role as competing endogenous RNAs (ceRNA) sponging miR-200a. In vitro, circRNA-007371 promoted the ability of migration, growth, and blood vessel formation in EMOA murine endothelial cells using wound healing and tube formation assay. The AGO2-RIP and RNA-sequencing analysis in overexpression circRNA-007371 EMOA murine endothelial cells demonstrated that circRNA-007371 upregulates the stromal antigen 1 (Stag1) via spouse of miR-200a and HIF-1 signaling pathway might participate in the angiogenesis. Conclusions This study discovers that circRNA-007371, a novel ceRNA, is up-regulated, and enhances the angiogenesis via angiocrine role to regulate the STAG1-miR-200a-5p signaling pathway in liver fibrosis.