Elevated FOXG1 and SOX2 in glioblastoma enforces neural stem cell identity through transcriptional control of cell cycle and epigenetic regulators
Genes and Development
Cold Spring Harbor Laboratory Press
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Bulstrode, H., Johnstone, E., Marques-Torrejon, M., Ferguson, K., Bressan, R., Blin, C., Grant, V., et al. (2017). Elevated FOXG1 and SOX2 in glioblastoma enforces neural stem cell identity through transcriptional control of cell cycle and epigenetic regulators. Genes and Development, 31 (8), 757-773. https://doi.org/10.1101/gad.293027.116
Glioblastoma multiforme (GBM) is an aggressive brain tumor driven by cells with hallmarks of neural stem (NS) cells. GBM stem cells frequently express high levels of the transcription factors FOXG1 and SOX2. Here we show that increased expression of these factors restricts astrocyte differentiation and can trigger dedifferentiation to a proliferative NS cell state. Transcriptional targets include cell cycle and epigenetic regulators (e.g., Foxo3, Plk1, Mycn, Dnmt1, Dnmt3b, and Tet3). Foxo3 is a critical repressed downstream effector that is controlled via a conserved FOXG1/SOX2-bound cis-regulatory element. Foxo3 loss, combined with exposure to the DNA methylation inhibitor 5-azacytidine, enforces astrocyte dedifferentiation. DNA methylation profiling in differentiating astrocytes identifies changes at multiple polycomb targets, including the promoter of Foxo3 In patient-derived GBM stem cells, CRISPR/Cas9 deletion of FOXG1 does not impact proliferation in vitro; however, upon transplantation in vivo, FOXG1-null cells display increased astrocyte differentiation and up-regulate FOXO3. In contrast, SOX2 ablation attenuates proliferation, and mutant cells cannot be expanded in vitro. Thus, FOXG1 and SOX2 operate in complementary but distinct roles to fuel unconstrained self-renewal in GBM stem cells via transcriptional control of core cell cycle and epigenetic regulators.
glioblastoma, cell cycle, epigenetics, dedifferentiation, neural stem cell, astrocyte
H.B. was supported by a Wellcome Trust Clinician Research Training Fellowship. E.J. was supported by the Biotechnology and Biological Sciences Research Council. M.A.M.-T. is supported by an EMBO training fellowship. K.F. is supported by a studentship from Cancer Research UK (A19680). R.B. is supported by a studentship from the Science Without Borders Program (CAPES, Brazil). D.S. is a Cancer Research UK Career Development Fellow (reference C47648/A20837), and work in his laboratory is also supported by a Medical Research Council University grant to the MRC Human Genetics Unit. S.M.P. is a Cancer Research UK Senior Research Fellow (A17368).
External DOI: https://doi.org/10.1101/gad.293027.116
This record's URL: https://www.repository.cam.ac.uk/handle/1810/267368
Attribution-NonCommercial 4.0 International
Licence URL: http://creativecommons.org/licenses/by-nc/4.0/