CircPOLR2A Promotes Proliferation and Impedes Apoptosis of Glioblastoma Multiforme Cells by Up-regulating POU3F2 to Facilitate SOX9 Transcription

Abstract

Glioblastoma multiforme (GBM) is the most common cancer in nervous system around the world. Little advancement has been achieved in promoting prognosis of GBM patients. Circular RNAs (circRNAs) are suggested as crucial effectors in modulating GBM development. Hsa_circRNA_092437 (circPOLR2A), an up-regulated circRNA in GBM cells, has not been studied yet. In this study, RT-qPCR and western blot assays were applied to detect RNA and protein levels. Cell proliferation and apoptosis were analyzed via functional assays. Subcellular fractionation assay was carried out to determine circPOLR2A distribution in cells. Bioinformatics analysis and mechanism assays were done for detecting relationships among different factors. Rescue assays were performed to confirm validity of circPOLR2A/SOX9 axis. According to experimental results, circPOLR2A was up-regulated in GBM cells and promoted GBM cell proliferation while inhibiting GBM cell apoptosis. CircPOLR2A mainly existed in cell cytoplasm and sponged miR-2113 to positively regulate POU3F2 expression. POU3F2 activated the transcription of SOX9 through interacting with SOX9 promoter (1-500). Rescue assays validated that circPOLR2A influenced GBM cell proliferation and apoptosis via SOX9. To conclude, circPOLR2A enhanced the transcription of SOX9 through miR-2113/POU3F2 axis, thus exacerbating GBM cells growth.

Keywords: POU3F2; SOX9; ceRNA; circPOLR2A; glioblastoma multiforme; transcription factor.