FOXA1 mutations alter pioneering activity, differentiation and prostate cancer phenotypes

• Published in: Nature (London) Vol. 571; no. 7765; pp. 408 - 412
• Main Authors: Adams, Elizabeth J., Karthaus, Wouter R., Hoover, Elizabeth, Liu, Deli, Gruet, Antoine, Zhang, Zeda, Cho, Hyunwoo, DiLoreto, Rose, Chhangawala, Sagar, Liu, Yang, Watson, Philip A., Davicioni, Elai, Sboner, Andrea, Barbieri, Christopher E., Bose, Rohit, Leslie, Christina S., Sawyers, Charles L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2019; Nature Publishing Group
• Subjects: 631/208/176; 631/208/199; 631/67/589/466; 631/80/304; 692/420/755; Amino Acid Sequence; Animals; Assaying; Base Sequence; Binding; Binding Sites; Bioinformatics; Biological properties; Cell Differentiation - genetics; Cell Lineage; Chromatin; Chromatin - genetics; Chromatin - metabolism; CRISPR; Deoxyribonucleic acid; Differentiation; Disease Progression; DNA; Forkhead protein; Gene expression; Gene Expression Regulation, Neoplastic; Genetic aspects; Genomes; Genotype & phenotype; Growth factors; Health aspects; Hepatocyte Nuclear Factor 3-alpha - chemistry; Hepatocyte Nuclear Factor 3-alpha - genetics; Histology; Humanities and Social Sciences; Humans; Interrogation; Letter; Male; Mesenchyme; Metastases; Metastasis; Mice; Mice, Inbred NOD; multidisciplinary; Mutants; Mutation; Mutation (Biology); Nucleotide Motifs; Organoids; Organoids - cytology; Organoids - metabolism; Phenotype; Phenotypes; Prostate cancer; Prostatic Neoplasms - genetics; Prostatic Neoplasms - pathology; Risk factors; Science; Science (multidisciplinary); Transcription factors; Transposase; Tumors; United States
• ISSN: 0028-0836; 1476-4687; 1476-4687
• DOI: 10.1038/s41586-019-1318-9

Mutations in the transcription factor FOXA1 define a unique subset of prostate cancers but the functional consequences of these mutations and whether they confer gain or loss of function is unknown 1 – 9 . Here, by annotating the landscape of FOXA1 mutations from 3,086 human prostate cancers, we define two hotspots in the forkhead domain: Wing2 (around 50% of all mutations) and the highly conserved DNA-contact residue R219 (around 5% of all mutations). Wing2 mutations are detected in adenocarcinomas at all stages, whereas R219 mutations are enriched in metastatic tumours with neuroendocrine histology. Interrogation of the biological properties of wild-type FOXA1 and fourteen FOXA1 mutants reveals gain of function in mouse prostate organoid proliferation assays. Twelve of these mutants, as well as wild-type FOXA1, promoted an exaggerated pro-luminal differentiation program, whereas two different R219 mutants blocked luminal differentiation and activated a mesenchymal and neuroendocrine transcriptional program. Assay for transposase-accessible chromatin using sequencing (ATAC-seq) of wild-type FOXA1 and representative Wing2 and R219 mutants revealed marked, mutant-specific changes in open chromatin at thousands of genomic loci and exposed sites of FOXA1 binding and associated increases in gene expression. Of note, ATAC-seq peaks in cells expressing R219 mutants lacked the canonical core FOXA1-binding motifs (GTAAAC/T) but were enriched for a related, non-canonical motif (GTAAAG/A), which was preferentially activated by R219-mutant FOXA1 in reporter assays. Thus, FOXA1 mutations alter its pioneering function and perturb normal luminal epithelial differentiation programs, providing further support for the role of lineage plasticity in cancer progression. Mutations in the transcription factor FOXA1 that are common in prostate cancer result in gain-of-function effects that promote changes in the differentiation of tumour cells.