Background/Aims: Recently, the insulin-like growth factor mRNA-binding protein 3 (IMP3) has been reported to be involved in tumorigenesis. We aimed to study the expression and role of IMP3 in human glioblastoma. Methods: We analyzed the expression of IMP3 in 70 cases of glioma tissues, normal brain tissues and 5 kinds of cell lines using western blot. Immunohistochemistry (IHC) was used to evaluate the expression and distribution of IMP3 in glioma tissues. Colony formation, wound healing, migration and invasion assays and tumorigenesis in nude mice were used to explore the function of IMP3 in vitro and in vivo. The epithelial-mesenchymal transition (EMT)-related biomarkers were detected by western blot. Results: We found that the expression level of IMP3 was obviously higher in glioma tissues than that in normal brain tissues, and associated with glioma grade. In-vitro assays revealed that IMP3 overexpression significantly induced cell proliferation, migration, and invasion. Mechanically, IMP3 over-expression downregulated the expression of E-cadherin, but upregulated the expressions of N-cadherin, vimentin, snail, slug and MMP9. However, the inhibition of IMP3 impaired these oncogenic effects. In vivo assay also demonstrated that silencing of IMP3 inhibited tumor growth and improved survival of tumor-bearing xenograft nude mice. Conclusion: IMP3 can promote cell proliferation, migration and invasion by inducing EMT in glioblastoma. Thus, targeting IMP3 pathway may be a novel way to treat patients with glioblastoma.

To date, miR-148-3p and DNMT1‐recombinant human runt-related transcription factor 3 (RUNX3) axis have been linked to cell proliferation, migration, and invasion; however, their roles and relationships in human glioblastoma multiforme (GBM) are still not clear. Here we found that the expression of miR-148-3p in glioma tissues was decreased compared with adjacent nontumor tissues and correlated with WHO grade, tumor size, and prognosis as well as DNMT1 and RUNX3 expressions. Compared with NHA cells, the expression of miR-148-3p in U87 and U251 cells was also downregulated and accompanied with upregulation of DNMT1 and hypermethylation level of RUNX3 promoter region. miR-148-3p overexpression induced apoptosis and cell cycle arrest of U87 and U251 cells, and affected cell migration and invasion. miR-148-3p mimics effectively suppressed the expression of DNMT1 and methylation of RUNX3 promoter, finally upregulating RUNX3 expression. Mechanistically, the 3′-untranslated region (3′-UTR) of DNMT1 was a direct target of miR-148-3p. Overexpression of miR-148-3p or inhibition of DNMT1 induced the expression of E-cadherin and reduced the expressions of N-cadherin, vimentin, MMP-2, and MMP-9. In conclusion, miR-148-3p directly repressed the expression of DNMT1 and inhibited proliferation, migration, and invasion by regulating DNMT1‐RUNX3 axis and the epithelial‐mesenchymal transition in GBM. Our findings provide a new foundation for treatment of patients with GBM.