Somatic ERCC2 Mutations Are Associated with a Distinct Genomic Signature in Urothelial Tumors

Alterations in DNA repair pathways are common in tumors and can result in characteristic mutational signatures; however, a specific mutational signature associated with somatic alterations in the nucleotide excision repair (NER) pathway has not yet been identified. Here, we examine the mutational processes operating in urothelial cancer, a tumor type in which the core NER gene ERCC2 is significantly mutated. Analysis of three independent urothelial tumor cohorts reveals a strong association between somatic ERCC2 mutations and activity of a mutational signature characterized by a broad spectrum of base changes. In addition, we note an association between activity of this signature and smoking that is independent of ERCC2 mutation status, providing genomic evidence of tobacco-related mutagenesis in urothelial cancer. Together, these analyses identify the first NER-related mutational signature and highlight the related roles of DNA damage and subsequent DNA repair in shaping the tumor mutational landscape.