Human tumorigenesis induced by an endogenous DNA transposase

Genomic rearrangements are a hallmark of childhood cancers, but the mutational processes underlying most of these variants remain unknown. We identified piggyBac transposable element derived 5 (PGBD5) as a highly expressed, enzymatically active domesticated human DNA transposase in a large subset of pediatric solid tumors, including rhabdoid tumors. Ectopic expression of PGBD5 in primary human cells was sufficient to induce fully penetrant cell transformation both in vitro and in immunodeficient mice in vivo. This activity required specific catalytic aspartic acid residues in the PGBD5 transposase domain as well as cellular non-homologous end-joining DNA repair, and was associated with distinct structural rearrangements defined by specific DNA sequence motifs. Similar genomic alterations, some recurrent, were found in primary human rhabdoid tumors. Thus, PGBD5 represents a new class of developmental oncogenic mutators in childhood solid tumors. ChIP-sequencing of PGBD5 and histone modifications in human rhadboid tumor cells and immortalized retinal epithelium.