The splicing factor U2AF1 contributes to cancer progression through a non-canonical role in translation regulation

Abstract

Somatic mutations in the genes encoding components of the spliceosome occur frequently in human neoplasms, including myeloid dysplasias and leukemias and less often in solid tumors. One of the affected factors, U2AF1, is involved in splice site selection, and the most common change, S34F, alters a conserved nucleic acid binding domain, recognition of the 3-splice site, and alternative splicing of many mRNAs. However, the role that this mutation plays in oncogenesis is still unknown. Here, we have uncovered a non-canonical function of U2AF1, showing that it binds mature mRNA in the cytoplasm and negatively regulates mRNA translation. This splicing-independent role of U2AF1 is altered by the S34F mutation, and polysomal profiling indicates the mutation affects translation of hundreds of mRNA. One functional consequence is increased synthesis of the secreted chemokine interleukin 8 which contributes to metastasis, inflammation, and cancer progression in mice and humans.