Profiling and Bioinformatics Analyses of Differential Circular RNA Expression in Glioblastoma Multiforme Cells Under Hypoxia

Abstract

BackgroundThe hypoxia microenvironment is highly associated with GBM's malignant phenotypes. CircRNAs were reported involved in GBM's biological characteristics and regulated by HIF-1α. However, the differential expression pro le and role of circRNAs in GBM cells under hypoxia are still unclear. MethodsThe expression pro les of circRNAs in LN229 and T98G under hypoxia were explored via circRNA sequencing analysis. Those circRNAs signi cantly dysregulated both in LN229 and T98G, and could be found in circBase were selected and validated by qRT-PCR, RNase R digestion reaction and Sanger sequencing. Normal cell line and fresh GBM tissues were also used for qRT-PCR validation. The roles of differentially expressed circRNAs were evaluated by bioinformatics analyses. ResultsThere were 672 dysregulated circRNAs in LN229 and 698 dysregulated circRNAs in T98G. GO analysis indicated that the alteration of circRNAs expression related to GBM cell's biogenesis and metabolism. KEGG analysis demonstrated that TGF-β signaling pathway, HIF-1 signaling pathway and metabolism related signaling pathway were closely associated with differentially expressed circRNAs under hypoxia.These results were con rmed by GSEA analysis. The 6 selected and dysregulated circRNAs both in LN229 and T98G including hsa_circ_0000745, hsa_circ_0020093, hsa_circ_0020094, hsa_circ_0000943, hsa_circ_0004874 and hsa_circ_0002359 were validated by qRT-PCR. Inhibition of hsa_circ_0000745 inhibited GBM cell's proliferation, migration and invasion. HIF-1α centered circRNA-miRNA-mRNA networks analysis showed that the 6 validated circRNAs could cross-talk with 11 related miRNAs. ConclusionThe circRNA expressions are dysregulated in GBM cell under hypoxia. The 6 validated circRNAs could participate in GBM's development and progression when hypoxia occurs. They might be the candidates for prognostic markers and adjuvant therapeutics of GBM in the future.

The landscape of circRNAs in gliomas temozolomide resistance: Insights into molecular pathways

“…CircCD44 expression is downregulated in GBM tissues and cell lines. Furthermore, overexpression of circCD44 reduced GBM cell invasion, proliferation, and colony formation [ 79 , 81 ].…”

Role of Non-Coding RNAs in TGF-β Signalling in Glioma

“…Chen et al performed circular RNA sequencing in LN229 and T98G GBM cells and identified several differentially expressed circular RNAs. KEGG and gene ontology analysis of the top-upregulated circular RNAs revealed that TGF-β is a vital pathway regulated by the top-candidate circular RNAs [102]. Further mechanistic studies are required to functionally characterize these candidate circular RNAs and their role in the TGF-β pathway in GBM [102].…”