Recurrent mutations in topoisomerase IIα cause a previously undescribed mutator phenotype in human cancers

Abstract

Significance Topoisomerases are crucial for genome maintenance and are targets for several chemotherapeutic agents. While anticancer drugs targeting topoisomerases can lead to secondary malignancies, there have been no descriptions of genetic defects in topoisomerases having roles in cancer development. Here we show that a somatic topoisomerase IIα mutation found in human tumors results in a mutator phenotype. We show that this mutation and the concomitant mutational signature, which we call ID_TOP2α, are associated with genomic rearrangements and with potentially oncogenic indel mutations in known driver genes. Our results shed new light on topoisomerase IIα function, on repair of trapped cleavage complexes, and on a likely oncogenic role for topoisomerases.