Treatment of glioblastoma multiforme using a combination of small interfering RNA targeting epidermal growth factor receptor and β‐catenin

Abstract

Background EGFR and β-catenin are two key mediators of cell signal transduction implicated in the pathogenesis of a variety of tumors. There is emerging evidence indicating that they are overexpressed in glioblastoma multiforme (GBM) and both play significant roles in GBM carcinogenesis. Moreover, down-regulating EGFR individually only provide limited therapeutic efficacy. Therefore, we sought to determine the feasibility and efficacy of gene therapy of GBM using combinatorial inhibition of EGFR and β-catenin in view of the crosstalk between these two signaling pathways. Methods The down-regulatory effect of siRNA targeting EGFR and β-catenin alone or in combination in human GBM cells U-87 MG was evaluated by Real-time PCR. Cell proliferation in the short and long term was investigated by Alamar blue and clonogenic assays, respectively. Annexin-V assay was performed to detect apoptosis caused by siRNA treatment. The effect of downregulating EGFR and β-catenin on cell cycle progression, cell migration and invasive potential were also examined. Results The siRNA treatment potently reduced gene expression of EGFR and β-catenin at the mRNA level. Simultaneous inhibition of EGFR and β-catenin greatly decreased GBM cell proliferation. Although no significant increase in apoptosis was demonstrated, combinatorial siRNA treatment delayed the progression of cell cycle with an increased proportion of cells arrested in the G0/1 phase. Furthermore, EGFR and β-catenin siRNA in combination significantly inhibited the migratory and invasive ability of GBM cells as evidenced. Conclusions Simultaneous inhibition of EGFR and β-catenin expression could represent an effective therapy for human GBM, and warrants further study in vivo.

MicroRNA-542-3p Suppresses Tumor Cell Invasion via Targeting AKT Pathway in Human Astrocytoma

“…A high level of ␤-catenin is associated with histopathological grades of astrocytoma and promotes the invasive capacity of glioblastoma cells (39), whereas inhibition of ␤-catenin activity results in the opposite effects (40). Because of the crucial roles of ␤-catenin in the development and progression of astrocytoma, targeting aberrant activity of ␤-catenin signaling in astrocytoma is considered to be an applicable approach to anticancer therapy (41)(42)(43). Our demonstration that ectopic miR-542-3p not only decreased nuclear translocation of ␤-catenin through enhancing the activity of tumor suppressor GSK-3␤ due to inhibition of AKT activity but also repressed the transactivation activity of ␤-catenin via reducing AKT-mediated phosphorylation at the Ser-552 site to exert an anti-invasive effect on glioblastoma cells suggests that miR-542-3p might be a promising molecular therapeutic target for high grade astrocytoma.…”

A Critical Overview of Targeted Therapies for Glioblastoma

“…Similarly, small-interfering RNA (siRNA)-based downregulation of DNA repair protein MGMT in tumor cells can enhance the chemosensitivity of malignant gliomas against temozolomide ( 92 ). The siRNA applied to glioblastoma cells in vitro was shown to reduce gene expression of EGFR and β-catenin and significantly inhibit their migratory as well as invasive ability ( 93 ). This is potentially an effective therapy for human glioblastoma and warrants further study in vivo .…”

Receptor-Targeted Glial Brain Tumor Therapies

“…Treatment arrested glioma cells in the G2/M phase, significantly inhibiting cell growth in vitro. The siRNA also reduced tumor growth in vivo [ 197 ]. Erlotinib, an EGFR inhibitor, was not able to show significant effects in multicenter Phase I/II trial [ 198 ].…”