Topographic correlates of driver mutations and endogenous gene expression in pediatric diffuse midline gliomas and hemispheric high-grade gliomas

Soonmee Cha,Armine Darbinyan,Eve Kazarian,Asher Marks,Sabine Mueller,Elizabeth Tong,Jin Cui,Mariam S Aboian

doi:10.1038/s41598-021-92943-0

Abstract

We evaluate the topographic distribution of diffuse midline gliomas and hemispheric high-grade gliomas in children with respect to their normal gene expression patterns and pathologic driver mutation patterns. We identified 19 pediatric patients with diffuse midline or high-grade glioma with preoperative MRI from tumor board review. 7 of these had 500 gene panel mutation testing, 11 patients had 50 gene panel mutation testing and one 343 gene panel testing from a separate institution were included as validation set. Tumor imaging features and gene expression patterns were analyzed using Allen Brain Atlas. Twelve patients had diffuse midline gliomas and seven had hemispheric high-grade gliomas. Three diffuse midline gliomas had the K27M mutation in the tail of histone H3 protein. All patients undergoing 500 gene panel testing had additional mutations, the most common being in ACVR1, PPM1D, and p53. Hemispheric high-grade gliomas had either TP53 or IDH1 mutation and diffuse midline gliomas had H3 K27M-mutation. Gene expression analysis in normal brains demonstrated that genes mutated in diffuse midline gliomas had higher expression along midline structures as compared to the cerebral hemispheres. Our study suggests that topographic location of pediatric diffuse midline gliomas and hemispheric high-grade gliomas correlates with driver mutations of tumor to the endogenous gene expression in that location. This correlation suggests that cellular state that is required for increased gene expression predisposes that location to mutations and defines the driver mutations within tumors that arise from that region.

Highlights

We evaluate the topographic distribution of diffuse midline gliomas and hemispheric high-grade gliomas in children with respect to their normal gene expression patterns and pathologic driver mutation patterns
Pediatric high-grade gliomas can be distinguished by their location of origin; hemispheric high-grade gliomas originate in the cerebral hemispheres and diffuse midline gliomas originate in the midline structures, commonly in the pons, thalamus, or spinal c ord[8,10,12,13,14,15]
We report the imaging features of pediatric high-degrade gliomas that are located along the midline and within the cerebral hemispheres and that had targeted next-generation gene sequencing analysis

Summary

Introduction

We evaluate the topographic distribution of diffuse midline gliomas and hemispheric high-grade gliomas in children with respect to their normal gene expression patterns and pathologic driver mutation patterns. Previous studies have shown that chromatin structure affects distribution and types of mutations in c ancer[16] To test this hypothesis, we analyzed normal gene expression profile within different parts of the brain using microarray data from publicly available Allen Brain Atlas and correlated expression patterns of genes that were characterized to be driver mutations in high-grade gliomas that originated from these locations. The Allen Brain Atlas provides data for normal intracranial gene expression in human adult and developmental brain (www.brain-map.org) This correlation would suggest that presence of chromatin microenvironment that is required for increased gene expression predisposes that location to mutations and defines the driver mutations within a specific region of the brain that led to tumor formation. Confirmation of gene expression patterns within specific regions of the brain associated with the presence of high-grade gliomas will lead to a better understanding of key genetic drivers involved in brain tumorigenesis

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