Circular extrachromosomal DNA promotes tumor heterogeneity in high-risk medulloblastoma
Chapman OS, Luebeck J, Sridhar S, Wong IT, Dixit D, Wang S, Prasad G, Rajkumar U, Pagadala MS, Larson JD, He BJ, Hung KL, Lange JT, Dehkordi SR, Chandran S, Adam M, Morgan L, Wani S, Tiwari A, Guccione C, Lin Y, Dutta A, Lo YY, Juarez E, Robinson JT, Korshunov A, Michaels JA, Cho YJ, Malicki DM, Coufal NG, Levy ML, Hobbs C, Scheuermann RH, Crawford JR, Pomeroy SL, Rich JN, Zhang X, Chang HY, Dixon JR, Bagchi A, Deshpande AJ, Carter H, Fraenkel E, Mischel PS, Wechsler-Reya RJ, Bafna V, Mesirov JP, Chavez L
Circular extrachromosomal DNA (ecDNA) in patient tumors is an important driver of oncogenic gene expression, evolution of drug resistance and poor patient outcomes. Applying computational methods for the detection and reconstruction of ecDNA across a retrospective cohort of 481 medulloblastoma tumors from 465 patients, we identify circular ecDNA in 82 patients (18%). Patients with ecDNA-positive medulloblastoma were more than twice as likely to relapse and three times as likely to die within 5 years of diagnosis. A subset of tumors harbored multiple ecDNA lineages, each containing distinct amplified oncogenes. Multimodal sequencing, imaging and CRISPR inhibition experiments in medulloblastoma models reveal intratumoral heterogeneity of ecDNA copy number per cell and frequent putative 'enhancer rewiring' events on ecDNA. This study reveals the frequency and diversity of ecDNA in medulloblastoma, stratified into molecular subgroups, and suggests copy number heterogeneity and enhancer rewiring as oncogenic features of ecDNA.