SP1-IKBIP axis promotes the proliferation and invasion of glioma with Wnt/β-catenin associated epithelial-mesenchymal transition

Glioma is the most aggressive tumor of the central nervous system and is associated with poor prognosis, especially in patients with high-grade gliomas. In this study, we investigated the biological role of inhibitor of kappa B kinase interacting protein (IKBIP) in promoting the progression of glioma. Analysis of the TCGA and GTEx databases revealed that IKBIP is upregulated in both lower-grade gliomas (LGG) and glioblastomas (GBM) compared with normal brain tissues. Kaplan-Meier survival analysis demonstrated that IKBIP upregulation is associated with shorter overall survival (OS) and disease-specific survival (DSS) in patients with LGG. Pan-cancer analysis indicated that IKBIP is aberrantly expressed in various malignant tumors, including gliomas. IKBIP knockdown inhibited the proliferation of glioma cells both in vitro and in vivo . Additionally, IKBIP knockdown in U251 and U87 glioma cell lines significantly suppressed their invasive capacity. Furthermore, IKBIP knockdown resulted in decreased expression of proteins associated with Wnt/β-catenin/epithelial-mesenchymal transition (EMT) pathway, including β-catenin, ZEB1, ZEB2, N-cadherin, whereas the expression of E-cadherin was increased. Conversely, IKBIP overexpression reduced the level of phosphorylated β-catenin (p-β-catenin) while increasing the expression of total β-catenin in glioma cells. Furthermore, we identified that transcription factor SP1 (Specificity Protein 1), which is also upregulated in glioma tissues and cell lines and is associated with the malignant phenotype of glioma, can bind to the promoter region of IKBIP. Upregulation of SPI in glioma cells significantly increased the expression level of IKBIP, while inhibiting the phosphorylation of β-catenin. These findings collectively suggest that upregulation of IKBIP promotes the proliferation and invasive behaviors of glioma cells by activating the Wnt/β-catenin/EMT pathway. Overall, our findings suggest that SP1-IKBIP axis facilitates the proliferation and invasion of glioma through Wnt/β-catenin-associated EMT, and SP1-IKBIP axis may represent a promising target for the clinical diagnosis and treatment of glioma.