Mesenchymal high-grade glioma is maintained by the ID-RAP1 axis
Francesco Niola, … , Antonio Iavarone, Anna Lasorella
Francesco Niola, … , Antonio Iavarone, Anna Lasorella
Published December 17, 2012
Citation Information: J Clin Invest. 2013;123(1):405-417. https://doi.org/10.1172/JCI63811.
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Mesenchymal high-grade glioma is maintained by the ID-RAP1 axis

Abstract

High-grade gliomas (HGGs) are incurable brain tumors that are characterized by the presence of glioma-initiating cells (GICs). GICs are essential to tumor aggressiveness and retain the capacity for self-renewal and multilineage differentiation as long as they reside in the perivascular niche. ID proteins are master regulators of stemness and anchorage to the extracellular niche microenvironment, suggesting that they may play a role in maintaining GICs. Here, we modeled the probable therapeutic impact of ID inactivation in HGG by selective ablation of Id in tumor cells and after tumor initiation in a new mouse model of human mesenchymal HGG. Deletion of 3 Id genes induced rapid release of GICs from the perivascular niche, followed by tumor regression. GIC displacement was mediated by derepression of Rap1gap and subsequent inhibition of RAP1, a master regulator of cell adhesion. We identified a signature module of 5 genes in the ID pathway, including RAP1GAP, which segregated 2 subgroups of glioma patients with markedly different clinical outcomes. The model-informed survival analysis together with genetic and functional studies establish that ID activity is required for the maintenance of mesenchymal HGG and suggest that pharmacological inactivation of ID proteins could serve as a therapeutic strategy.

Authors

Francesco Niola, Xudong Zhao, Devendra Singh, Ryan Sullivan, Angelica Castano, Antonio Verrico, Pietro Zoppoli, Dinorah Friedmann-Morvinski, Erik Sulman, Lindy Barrett, Yuan Zhuang, Inder Verma, Robert Benezra, Ken Aldape, Antonio Iavarone, Anna Lasorella

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Figure 3

The effect of Id ablation in Ras-V12-IRES-Cre-ER-shp53 GICs in vitro and after orthotopic transplantation in vivo.

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The effect of Id ablation in Ras-V12-IRES-Cre-ER-shp53 GICs in vitro and...
(A) Cells isolated from Ras-V12-IRES-Cre-ER-shp53 gliomas generated in Id-cTKO mice were cultured in medium containing EGF and FGF-2 for 3 passages and immunostained using antibodies against Nestin, SSEA1, and integrin α6 (ITGα6). Scale bars: 20 mm. (B) Microphotographs of tumor spheres from GICs 14 days after plating at <1 cell per μl in semiadherent conditions. GICs isolated from advanced Ras-V12-IRES-Cre-ER-shp53 gliomas in Id-cTKO or wild-type control mice were cultured in medium containing EGF and FGF-2 for 2 passages and then subjected to treatment with vehicle or 4-OHT for 5 days. Dissociated cells were assayed by microscopic analysis for sphere formation. Scale bars: 500 mm (top panels); 250 mm (bottom panels). (C) Quantification of gliomaspheres as a percentage of plated cells from cultures with the indicated genotypes and treatments. Data represent the mean ± SD of triplicate samples; *P = 0.003. (D) Regression plot for cells isolated from controls or tamoxifen-treated tumors. Cells from 2 independent tumors per treatment were plated at limiting dilution (1–400 cells per well) in triplicate plates. Data represent the mean ± SD; P = 0.006. Experiments were repeated twice. (E) H&E staining of representative brain sections of immunodeficient mice subjected to stereotaxic injection with Ras-V12-IRES-Cre-ER-shp53 Id-cTKO GICs and treated with oil or tamoxifen. Scale bars: 250 mm.