title: Recurrent DICER1 hotspot mutations in endometrial tumours and their impact on microRNA biogenesis.
abstract: DICER1 plays a critical role in microRNA (miRNA) biogenesis. Recurrent somatic 'hotspot' mutations at the four metal-binding sites within the RNase IIIb domain of DICER1 were identified in ovarian sex cord-stromal tumours and have since been described in other paediatric tumours. In this study, we screened the RNase IIIb domain of DICER1 in 290 endometrial tumours and identified six cases with hotspot mutations, including two cases affected by an atypical G1809R mutation directly adjacent to a metal-binding site. Using Illumina and Sanger targeted resequencing, we observed and validated biallelic DICER1 mutations in several cases with hotspot mutations. Through in vitro DICER1 cleavage assays, small RNA deep sequencing and real-time PCR, we demonstrated that mutations adding a positively charged side chain to residue 1809 have similar detrimental effects on 5p miRNA production to mutations at the metal-binding sites. As expected, 5p miRNAs were globally reduced in tumours and cell lines with hotspot mutations. Pathway analysis of gene expression profiles indicated that genes de-repressed due to loss of 5p miRNAs are strongly associated with pathways regulating the cell cycle. Using a Dicer1-null mouse cell line model, we found that expression of DICER1 hotspot mutants promoted cell proliferation, whereas wild-type (WT) DICER1 inhibited cell proliferation. Furthermore, targets of let-7 family miRNAs are enriched among the up-regulated genes, suggesting that loss of let-7 may be impacting downstream pathways. Our results reveal that DICER1 hotspot mutations are implicated in common malignancies and may constitute a unique oncogenic pathway.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.|Center for Translational and Applied Genomics, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Jiamin
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.|Center for Translational and Applied Genomics, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Yemin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.|Center for Translational and Applied Genomics, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Melissa K
authors.initials: MK
authors.lastname: McMonechy
authors.affiliation: Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Anglesio
authors.affiliation: Center for Translational and Applied Genomics, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Winnie
authors.initials: W
authors.lastname: Yang
authors.affiliation: Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Janine
authors.initials: J
authors.lastname: Senz
authors.affiliation: Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Maines-Bandiera
authors.affiliation: Department of Molecular Oncology, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Jamie
authors.initials: J
authors.lastname: Rosner
authors.affiliation: Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Genny
authors.initials: G
authors.lastname: Trigo-Gonzalez
authors.affiliation: Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: S W
authors.initials: SW
authors.lastname: Grace Cheng
authors.affiliation: Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Jaeyeon
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Martin M
authors.initials: MM
authors.lastname: Matzuk
authors.affiliation: Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.|Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Gregg B
authors.initials: GB
authors.lastname: Morin
authors.affiliation: Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.|Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, BC, Canada.|Center for Translational and Applied Genomics, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: David G
authors.initials: DG
authors.lastname: Huntsman
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D053487:DEAD-box RNA Helicases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D004252:DNA Mutational Analysis; D016889:Endometrial Neoplasms / Q000201:enzymology* / Q000235:genetics* / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D053263:Gene Regulatory Networks; D020022:Genetic Predisposition to Disease; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D018345:Mice, Knockout; D035683:MicroRNAs / Q000096:biosynthesis* / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D043244:Ribonuclease III / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D035683:MicroRNAs; C487931:mirnlet7 microRNA, human; C542687:mirnlet7 microRNA, mouse; C408087:DICER1 protein, human; C509781:Dicer1 protein, mouse; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases
keywords: DICER1; cell cycle; hotspot mutations; let-7; miRNA