Small Extracellular Vesicles from Radioresistant H3K27M-Pediatric Diffuse Midline Glioma Cells Modulate Tumor Phenotypes and Radiation Response [bulk RNA-seq]

Pediatric diffuse midline gliomas harboring the Histone 3 lysine 27-to-methionine mutation (H3K27M-pDMG) represent a highly heterogenous group of brain tumors characterized by intrinsic resistance to radiation therapy, the current standard of care. Recent evidence suggests that intratumor small extracellular vesicle (sEV)-mediated signaling plays an oncogenic role among glioma stem cell populations. However, the dynamics and functional roles of H3K27M-pDMG derived sEVs in the context of radiation-induced stress remain unclear. In this study, we characterize sEV uptake dynamics between H3K27M tumor cells, identify potential sEV surface proteins involved in the process, and demonstrate that radioresistant (RR) H3K27M-pDMG-derived sEVs confer radioprotective effects to radiosensitive (RS) H3K27M-pDMG cells at the population level. RR-sEVs induce metabolic and gene expression changes in RS cell populations within the timescale of EV uptake and internalization, leading to improved DNA repair following radiation-induced stress. Furthermore, we identified the proteins, microRNAs (miRNAs), and metabolites present in RR-sEVs, shedding light on the molecular cargo that may be responsible for these effects. Our findings provide insights into the intrinsic radioresistant properties mediated by H3K27M-pDMG-derived sEVs and propose novel targets for disrupting radioresistant intratumoral communication in H3K27M-pDMGs.