Gene expression analysis was performed in Glioblastoma tumor samples and normal controls from Kunming, The Cancer Genome Atlas Glioblastoma Multiforme (TCGA-Glioblastoma) cohort, and the Gene Expression Omnibus (GEO) database (GSE7696). Cell proliferation, apoptosis, Matrigel Transwell, colony formation, and cell cycle assays were performed in T98 G and U251 cells in vitro. An orthotopic U251 xenograft murine model was employed to test the effects of RP3-439F8.1 knockdown in vivo.

NR5A2 was upregulated in the three independent Glioblastoma tumor cohorts. In vitro, NR5A2 overexpression enhanced Glioblastoma cell proliferation, colony formation, invasiveness, and G0-G1 cell cycle phase shift via co-activating β-catenin/TCF4 signaling, with no apparent effect upon apoptosis. In contrast, RP3-439F8.1 knockdown produced the opposite effects. RP3-439F8.1 knockdown reduced tumor progression in vivo, increasing overall survival in model mice. Further in vitro experiments revealed that RP3-439F8.1 acts as a competing endogenous RNA (ceRNA) to regulate NR5A2 by sponging the microRNA miR-139-5p. These findings were clinically validated by a positive correlation between RP3-439F8.1 and NR5A2 and a negative correlation between RP3-439F8.1 and miR-139-5p in Glioblastoma tumors.

The study supports a tumorigenic role for RP3-439F8.1 in Glioblastoma through the RP3-439F8.1/miR-139-5p/NR5A2 axis ¹⁾