Developing a multidisciplinary strategy to interpret the impact of missense mutations in XPA on NER activity and cisplatin sensitivity

Nucleotide excision repair (NER) is an essential DNA damage repair pathway that removes bulky DNA lesions formed by exposure to ultraviolet light, environmental toxins, and platinum (Pt)-based chemotherapeutic drugs that are a standard of care for many cancer types. Mutation or decreased NER gene expression in cancer correlates with improved patient survival after Pt-based chemotherapy. However, the impact of most missense mutations in NER genes is unknown, and few approaches exist to reliably identify nonrecurrent passenger mutations with functional consequences. In this study, a multidisciplinary strategy will be developed to predict, validate, and characterize NER-defective mutations in the essential NER scaffold protein Xeroderma Pigmentosum Complementation Group A (XPA). Computational analyses were used to score NER-deficient versus NER-proficient mutations for further study. Predicted NER-deficient XPA mutants are being expressed in human XPA-deficient cells and screened for both NER activity and cisplatin sensitivity. In-depth biophysical and structural studies are being implemented to elucidate mechanisms of dysfunction. Identifying NER-deficient mutations that may sensitize tumors to Pt-based chemotherapies represents a promising strategy to stratify patients for optimal treatment strategies.