title: Wild-Type U2AF1 Antagonizes the Splicing Program Characteristic of U2AF1-Mutant Tumors and Is Required for Cell Survival.
abstract: We have asked how the common S34F mutation in the splicing factor U2AF1 regulates alternative splicing in lung cancer, and why wild-type U2AF1 is retained in cancers with this mutation. A human lung epithelial cell line was genetically modified so that U2AF1S34F is expressed from one of the two endogenous U2AF1 loci. By altering levels of mutant or wild-type U2AF1 in this cell line and by analyzing published data on human lung adenocarcinomas, we show that S34F-associated changes in alternative splicing are proportional to the ratio of S34F:wild-type gene products and not to absolute levels of either the mutant or wild-type factor. Preferential recognition of specific 3' splice sites in S34F-expressing cells is largely explained by differential in vitro RNA-binding affinities of mutant versus wild-type U2AF1 for those same 3' splice sites. Finally, we show that lung adenocarcinoma cell lines bearing U2AF1 mutations do not require the mutant protein for growth in vitro or in vivo. In contrast, wild-type U2AF1 is required for survival, regardless of whether cells carry the U2AF1S34F allele. Our results provide mechanistic explanations of the magnitude of splicing changes observed in U2AF1-mutant cells and why tumors harboring U2AF1 mutations always retain an expressed copy of the wild-type allele.
authors: Cancer Biology Section, Cancer Genetics Branch, National Human Genome Research Institute, Bethesda, United States Of America.|Department of Medicine, Meyer Cancer Center, Weill Cornell Medicine, New York, United States Of America.
authors: Dennis Liang
authors: DL
authors: Fei
authors: Cancer Biology Section, Cancer Genetics Branch, National Human Genome Research Institute, Bethesda, United States Of America.
authors: Hayley
authors: H
authors: Motowski
authors: Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, Rochester, United States Of America.
authors: Rakesh
authors: R
authors: Chatrikhi
authors: Cancer Biology Section, Cancer Genetics Branch, National Human Genome Research Institute, Bethesda, United States Of America.
authors: Sameer
authors: http://orcid.org/0000-0003-2664-9521
authors: S
authors: Prasad
authors: Cancer Biology Section, Cancer Genetics Branch, National Human Genome Research Institute, Bethesda, United States Of America.
authors: Jovian
authors: http://orcid.org/0000-0001-9214-7576
authors: J
authors: Yu
authors: Genetics Branch, National Cancer Institute, Bethesda, United States Of America.
authors: Shaojian
authors: S
authors: Gao
authors: Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester Medical Center, Rochester, United States Of America.
authors: Clara L
authors: CL
authors: Kielkopf
authors: Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, United States Of America.|Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, United States Of America.
authors: Robert K
authors: http://orcid.org/0000-0002-8046-1063
authors: RK
authors: Bradley
authors: Cancer Biology Section, Cancer Genetics Branch, National Human Genome Research Institute, Bethesda, United States Of America.|Department of Medicine, Meyer Cancer Center, Weill Cornell Medicine, New York, United States Of America.
authors: Harold
authors: H
authors: Varmus
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology; D000077192:Adenocarcinoma of Lung; D017398:Alternative Splicing / Q000235:genetics*; D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics*; D002470:Cell Survival / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology; D051379:Mice; D050505:Mutant Proteins / Q000235:genetics; D009154:Mutation; D059372:Nucleotide Motifs / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D000072668:Splicing Factor U2AF / Q000096:biosynthesis / Q000235:genetics*; D059467:Transcriptome / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D050505:Mutant Proteins; D012333:RNA, Messenger; D000072668:Splicing Factor U2AF; C076753:U2AF1 protein, human