Project description:Embryonal tumours with multilayered rosettes (ETMRs) are aggressive paediatric embryonal brain tumours with a universally poor prognosis1. Here we collected 193 primary ETMRs and 23 matched relapse samples to investigate the genomic landscape of this distinct tumour type. We found that patients with tumours in which the proposed driver C19MC2-4 was not amplified frequently had germline mutations in DICER1 or other microRNA-related aberrations such as somatic amplification of miR-17-92 (also known as MIR17HG). Whole-genome sequencing revealed that tumours had an overall low recurrence of single-nucleotide variants (SNVs), but showed prevalent genomic instability caused by widespread occurrence of R-loop structures. We show that R-loop-associated chromosomal instability can be induced by the loss of DICER1 function. Comparison of primary tumours and matched relapse samples showed a strong conservation of structural variants, but low conservation of SNVs. Moreover, many newly acquired SNVs are associated with a mutational signature related to cisplatin treatment. Finally, we show that targeting R-loops with topoisomerase and PARP inhibitors might be an effective treatment strategy for this deadly disease.
Project description:ETMRs are aggressive pediatric embryonal brain tumors with universally dismal outcome. We collected 193 ETMR samples and an additional 23 matched relapses to investigate the genomic landscape of this distinct entity. We found that patients having tumors without C19MC amplification, the proposed driver, frequently harbor DICER1 germline mutations or other miRNA-related aberrations such as somatic miR-17-92 miRNA cluster amplifications. Despite these distinct genetic aberrations, no molecular subgrouping was observed. Whole-genome sequencing revealed an overall low recurrence of SNVs, but prevalent R-loop-associated chromosomal instability, of which we show that this can be induced by loss of DICER1 function. Comparing primary tumors and matched relapses revealed a strong conservation of SVs but low conservation of SNVs. Moreover, many newly acquired SNVs are associated to a new cisplatin treatment related mutational signature. Finally, we show that targeting R-loops with topoisomerase and PARP inhibitors might be an effective treatment strategy for this deadly disease.
Project description:ETMRs are aggressive pediatric embryonal brain tumors with universally dismal outcome. We collected 193 ETMR samples and an additional 23 matched relapses to investigate the genomic landscape of this distinct entity. We found that patients having tumors without C19MC amplification, the proposed driver, frequently harbor DICER1 germline mutations or other miRNA-related aberrations such as somatic miR-17-92 miRNA cluster amplifications. Despite these distinct genetic aberrations, no molecular subgrouping was observed. Whole-genome sequencing revealed an overall low recurrence of SNVs, but prevalent R-loop-associated chromosomal instability, of which we show that this can be induced by loss of DICER1 function. Comparing primary tumors and matched relapses revealed a strong conservation of SVs but low conservation of SNVs. Moreover, many newly acquired SNVs are associated to a new cisplatin treatment related mutational signature. Finally, we show that targeting R-loops with topoisomerase and PARP inhibitors might be an effective treatment strategy for this deadly disease.
