Michael Rusch, Aksana Vasilyeva, Marc Remke, Paul A. Northcott, Tanvi Sharma, Finn Wesenberg, Andrey Korshunov, Peter Lichter, Kristian W. Pajtler, Natalie Jäger, Sonia Partap, Till Milde, John R. Crawford, Amar Gajjar, Stefan Rutkowski, Nicholas G. Gottardo, Kyle S. Smith, Daniel C. Bowers, Christoffer Johansen, Sebastian M. Waszak, Tobias Rausch, Christelle Dufour, Damarys Loew, David T.W. Jones, Geoffrey Neale, Olaf Witt, Tone Eggen, Ivo Buchhalter, Olivier Ayrault, Dominik Sturm, Maria Feychting, Jesus Garcia-Lopez, Michael A. Grotzer, Claudia E. Kuehni, Emilie Indersie, Brandon J. Wainwright, Stéphanie Puget, Joy Nakitandwe, Marcel Kool, David W. Ellison, Marina Ryzhova, Jules Kerssemakers, Birgitta Lannering, Amy A Smith, Brent A. Orr, Joachim Schüz, Tina Veje Andersen, Murali Chintagumpala, Brian Gudenas, Bérangère Lombard, Antoine Forget, Laurence Brugières, Marija Kojic, Kim E. Nichols, Jennifer Hadley, Martin Röösli, Kristina Kjærheim, Anne Bendel, Stefan M. Pfister, Kayla V. Hamilton, Ruth G. Tatevossian, Giles W. Robinson, Jan O. Korbel, Institut Curie, PSL Research University, CNRS UMR, INSERM, Orsay, France. Université Paris Sud, Université Paris- Saclay, CNRS UMR 3347, INSERM U1021, Orsay, France., and Institut Curie [Paris]
Cancer genomics has illuminated a wide spectrum of genes and core molecular processes contributing to human malignancy. Still, the genetic and molecular basis of many cancers remains only partially explained. Genetic predisposition accounts for 5-10% of cancer diagnoses(1,2) and genetic events cooperating with known somatic driver events are poorly understood. Analyzing established cancer predisposition genes in medulloblastoma (MB), a malignant childhood brain tumor, we recently identified pathogenic germline variants that account for 5% of all MB patients(3). Here, by extending our previous analysis to include all protein-coding genes, we discovered and replicated rare germline loss-of-function (LoF) variants across Elongator Complex Protein 1 (ELP1) on 9q31.3 in 15% of pediatric MB(SHH) cases, thus implicating ELP1 as the most common MB predisposition gene and increasing genetic predisposition to 40% for pediatric MB(SHH). Inheritance was verified based on parent-offspring and pedigree analysis, which identified two families with a history of pediatric MB. ELP1-associated MBs were restricted to the molecular SHHα subtype(4) and were characterized by universal biallelic inactivation of ELP1 due to somatic loss of chromosome 9q. The majority of ELP1-associated MBs exhibited co-occurring somatic PTCH1 (9q22.32) alterations, suggesting that ELP1-deficiency predisposes to tumor development in combination with constitutive activation of SHH signaling. ELP1 is an essential subunit of the evolutionary conserved Elongator complex, whose primary function is to enable efficient translational elongation through tRNA modifications at the wobble (U(34)) position(5,6). Biochemical, transcriptional, and proteomic analyses revealed that ELP1-associated MB(SHH) are characterized by a destabilized core Elongator complex, loss of Elongator-dependent tRNA wobble modifications, codon-dependent translational reprogramming, and induction of the unfolded protein response (UPR), consistent with deregulation of protein homeostasis due to Elongator-deficiency in model systems(7–9). Our findings suggest that genetic predisposition to proteome instability is a previously underappreciated determinant in the pathogenesis of pediatric brain cancer. These results provide a strong rationale for further investigating the role of protein homeostasis in other cancer types and potential opportunities for novel therapeutic interference.