Circ_0000020 elevates the expression of PIK3CA and facilitates the malignant phenotypes of glioma cells via targeting miR-142-5p

BACKGROUND: Multiple circular RNAs (circRNAs) have been recently described as crucial oncogenic factors or tumor suppressors. This study aimed to investigate the role of circ_0000020 in glioma progression. METHODS: Circ_0000020 and miR-142-5p expressions in glioma samples were assessed through qRT-PCR, and then the association between pathological indexes and circ_0000020 expressions was analyzed. Functional experiment was performed with human glioma cell lines U251 and U87. Gain-of-function and loss-of-function models were established. CCK-8 assay was used to detect glioma cell proliferation. Transwell assay was used to examine glioma cell migration and invasion. The regulatory relationships among circ_0000020, miR-142-5p and phosphatidylinositol 3-kinase C (PIK3CA) were investigated by bioinformatics analysis, luciferase reporter assay, qRT-PCR and Western blot. In vivo tumorigenesis assay was performed with nude mice to further validate the demonstrations of in vitro experiments. RESULTS: Circ_0000020 expression in glioma samples was remarkably increased compared with that in normal brain tissues and its high expression was associated with unfavorable pathological indexes. Circ_0000020 overexpression remarkably accelerated proliferation, migration and invasion of glioma cells. Accordingly, circ_0000020 knockdown suppressed the malignant phenotypes of glioma cells. Circ_0000020 overexpression significantly reduced miR-142-5p expression by sponging it, and circ_0000020 could enhance the expression of PIK3CA, which was a target gene of miR-142-5p. CONCLUSIONS: Circ_0000020 promotes glioma progression via miR-142-5p/PIK3CA axis.