A synthetic BMP-2 mimicking peptide induces glioblastoma stem cell differentiation

Background: Glioblastoma (GBM) is the most aggressive type of primary brain tumor, characterized by the intrinsic resistance to chemotherapy due to the presence of a highly aggressive Cancer Stem Cell (CSC) sub population. In this context, Bone Morphogenetic Proteins (BMPs) have been demonstrated to induce CSC differentiation and to sensitize GBM cells to treatments. Methods: The BMP-2 mimicking peptide, named GBMP1a, was synthesized on solid-phase by Fmoc chemistry. Structural characterization and prediction of receptor binding were obtained by Circular Dicroism (CD) and NRM analyses. Activation of BMP signalling was evaluated by a luciferase reporter assay and western blot. Pro differentiating effects of GBMP1a were verified by immunostaining and neurosphere assay in primary glioblastoma cultures. Results: CD and NMR showed that GBMP1a correctly folds into expected tridimensional structures and predicted its binding to BMPR-IA to the same epitope as in the native complex. Reporter analysis disclosed that GBMP1a is able to activate BMP signalling in GBM cells. Moreover, BMP-signalling activation was specifically dependent on smad1/5/8 phosphorylation. Finally, we confirmed that GBMP1a treatment is sufficient to enhance osteogenic differentiation of Mesenchymal Stem Cells and to induce astroglial differentiation of glioma stem cells (GSCs) in vitro. Conclusions: GBMP1a was demonstrated to be a good inducer of GSC differentiation, thus being considered a potential anti-cancer tool to be further developed for GBM treatment.