circRNA derived from CLSPN (circCLSPN) is an oncogene in human glioblastoma multiforme by regulating cell growth, migration and invasion via ceRNA pathway.

Glioblastoma multiforme (GBM) is the most aggressive and prevalent brain tumor in adults. The circRNA derived from CLSPN (hsa_circ_0011591, circCLSPN) is remarkably upregulated in GBM; however its functional role was uncovered yet. First, we examined expression of circCLSPN using GSE109569 database and RT-qPCR, and circCLSPN level was upregulated in human GBM tumor tissues and cells (A172 and LN18); moreover, circCLSPN showed a stable structure stability. Then, a series of loss-of-functional experiments were performed using CCK-8 assay, colony formation assay, flow cytometry, scratch wound assay, and transwell assay. Consequently, circCLSPN silencing suppressed cell viability, colony formation ability, cell cycle progression, migration, and invasion of A172 and LN18 cells in vitro, and promoted apoptosis rate. Allied with those were decreased B cell lymphoma-2 (Bcl-2), matrix metalloproteinase-2 (MMP2) and MMP9 expression, and elevated Bcl-2-associated X protein (Bax) level. According to dual-luciferase reporter assay and RNA pull-down assay, miR-370-3p was identified to be targeted and sponged by circCLSPN, and further targeted and negatively regulated USP39. Functionally, overexpressing miR-370-3p could mimic in vitro effects of circCLSPN interference. Rescue experiments revealed that blocking miR-370-3p could partially reverse the suppression of circCLSPN knockdown on cell growth, migration and invasion, and role of miR- 370-3p overexpression was abrogated by restoring USP39. In vivo, circCLSPN knockdown hindered tumor growth of LN18 cells by affecting miR-370-3p, USP39, MMP2 and MMP9 expression. In conclusion, circCLSPN elicited an oncogenic role in tumorigenesis and malignant progression of human GBM cells through circCLSPN-miR-370-3p-USP39 pathway.