Gene expression profile of Radiatiom resistant BRAFV400E type pediatric low-grade gliomas

Inhibitors of the MAPK pathway (MAPKi) have shown significant activity in treatment of childhood BRAF-activated brain tumors. However, for tumors harboring BRAFV600E mutations, the drugs are rarely curative, and patients can become refractory to treatment. Combining MAPKi with low dose X-ray therapy (XRT) has the potential to improve the cure rate, but development of XRT resistance poses a major challenge. To understand the mechanisms of radiation resistance in BRAFV600E type pediatric low-grade gliomas, radiation resistance models were developed by using BT-40 and IC-3635, two pediatric low-grade glioma (PLGG) PDX models BRAFV600E mutation. RNA sequencing was performed to determine the gene expression profile of primary tumors and resistant tumors, and their response to XRT treatment. Each tumor tissue was transplanted to 12 scid mice, respectively. Treatment was started when tumor volume reach ~0.3~0.6 cm3. Tumors on mice were exposed locally to single dose 5Gy X-radiatiom, and tumor tissue (from three mice, triplicates) were collected at 0 (no treatment), 2, 8 and 24 hours post treatment, and were snap-frozen in liquid nitrogen. RNA was isolated and applied to subsequent 100bp paired read sequencing run with Illumina NovaSeq 6000 platform at 100 bp paired-end module.