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Sci Signal. 2019 Jan 22;12(565). pii: eaan8680. doi: 10.1126/scisignal.aan8680.

Transcriptional repressor REST drives lineage stage-specific chromatin compaction at Ptch1 and increases AKT activation in a mouse model of medulloblastoma.

Author information

1
Department of Pediatrics, University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.
2
Texas Children's Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA.
3
Department of Pediatrics, Northwestern University, Chicago, IL 60611, USA.
4
Department of Pediatrics, Emory University, Atlanta, GA 30322, USA.
5
Department of Pathology, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.
6
Department of Pathology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
7
Department of Pediatrics, University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA. vgopalak@mdanderson.org.
8
Molecular and Cellular Oncology, University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.
9
Brain Tumor Center, University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.
10
Center for Cancer Epigenetics, University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.
11
The University of Texas MD Anderson Cancer Center-University of Texas Health Science Center at Houston Graduate School of Biomedical Sciences, Houston, TX 77030, USA.

Abstract

In medulloblastomas (MBs), the expression and activity of RE1-silencing transcription factor (REST) is increased in tumors driven by the sonic hedgehog (SHH) pathway, specifically the SHH-α (children 3 to 16 years) and SHH-β (infants) subgroups. Neuronal maturation is greater in SHH-β than SHH-α tumors, but both correlate with poor overall patient survival. We studied the contribution of REST to MB using a transgenic mouse model (RESTTG ) wherein conditional NeuroD2-controlled REST transgene expression in lineage-committed Ptch1 +/- cerebellar granule neuron progenitors (CGNPs) accelerated tumorigenesis and increased penetrance and infiltrative disease. This model revealed a neuronal maturation context-specific antagonistic interplay between the transcriptional repressor REST and the activator GLI1 at Ptch1 Expression of Arrb1, which encodes β-arrestin1 (a GLI1 inhibitor), was substantially reduced in proliferating and, to a lesser extent, lineage-committed RESTTG cells compared with wild-type proliferating CGNPs. Lineage-committed RESTTG cells also had decreased GLI1 activity and increased histone H3K9 methylation at the Ptch1 locus, which correlated with premature silencing of Ptch1 These cells also had decreased expression of Pten, which encodes a negative regulator of the kinase AKT. Expression of PTCH1 and GLI1 were less, and ARRB1 was somewhat greater, in patient SHH-β than SHH-α MBs, whereas that of PTEN was similarly lower in both subtypes than in others. Inhibition of histone modifiers or AKT reduced proliferation and induced apoptosis, respectively, in cultured REST-high MB cells. Our findings linking REST to differentiation-specific chromatin remodeling, PTCH1 silencing, and AKT activation in MB tissues reveal potential subgroup-specific therapeutic targets for MB patients.

PMID:
30670636
DOI:
10.1126/scisignal.aan8680

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