title: Somatic MED12 mutations in prostate cancer and uterine leiomyomas promote tumorigenesis through distinct mechanisms.
abstract: BACKGROUND
  Mediator is a multiprotein interface between eukaryotic gene-specific transcription factors and RNA polymerase II. Mutations in exon 2 of the gene encoding MED12, a key subunit of the regulatory kinase module in Mediator, are extremely frequent in uterine leiomyomas, breast fibroadenomas, and phyllodes tumors. These mutations disrupt kinase module interactions and lead to diminished Mediator-associated kinase activity. MED12 mutations in exon 26, resulting in a substitution of leucine 1224 to phenylalanine (L1224F), have been recurrently observed in prostate cancer.
  
  
  METHODS
  To elucidate the molecular mechanisms leading to tumorigenesis in prostate cancer, we analyzed global interaction profiles of wild-type and L1224F mutant MED12 with quantitative affinity purification-mass spectrometry (AP-MS). Immunoprecipitation and kinase activity assay were used to further assess the interactions between Mediator complex subunits and kinase activity. The presence of L1224F mutation was analyzed in altogether 877 samples representing prostate hyperplasia, prostate cancer, and various tumor types in which somatic MED12 mutations have previously been observed.
  
  
  RESULTS
  In contrast to N-terminal MED12 mutations observed in uterine leiomyomas, the L1224F mutation compromises neither the interaction of MED12 with kinase module subunits Cyclin C and CDK8/19 nor Mediator-associated CDK activity. Instead, the L1224F mutation was shown to affect interactions between MED12 and other Mediator components (MED1, MED13, MED13L, MED14, MED15, MED17, and MED24). Mutation screening revealed one mutation in a Finnish (Caucasian) prostate cancer patient, whereas no mutations in any other tumor type were observed.
  
  
  CONCLUSIONS
  Specific somatic MED12 mutations in prostate cancer and uterine leiomyomas accumulate in two separate regions of the gene and promote tumorigenesis through clearly distinct mechanisms.
authors.affiliation: Genome-Scale Biology Research Program and Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland.
authors.forename: Kati
authors.initials: K
authors.lastname: Kämpjärvi
authors.affiliation: Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
authors.forename: Nam Hee
authors.initials: NH
authors.lastname: Kim
authors.affiliation: Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors.forename: Salla
authors.initials: S
authors.lastname: Keskitalo
authors.affiliation: Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
authors.forename: Alison D
authors.initials: AD
authors.lastname: Clark
authors.affiliation: Genome-Scale Biology Research Program and Department of Pathology, University of Helsinki, Helsinki, Finland.
authors.forename: Pernilla
authors.initials: P
authors.lastname: von Nandelstadh
authors.affiliation: Genome-Scale Biology Research Program and Department of Pathology, University of Helsinki, Helsinki, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Turunen
authors.affiliation: Genome-Scale Biology Research Program and Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland.
authors.forename: Tuomas
authors.initials: T
authors.lastname: Heikkinen
authors.affiliation: Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
authors.forename: Min Ju
authors.initials: MJ
authors.lastname: Park
authors.affiliation: Genome-Scale Biology Research Program and Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland.
authors.forename: Netta
authors.initials: N
authors.lastname: Mäkinen
authors.affiliation: Institute of Biosciences and Medical Technology - BioMediTech and Fimlab Laboratories, University of Tampere and Tampere University Hospital, Tampere, Finland.
authors.forename: Kati
authors.initials: K
authors.lastname: Kivinummi
authors.affiliation: Department of Clinical Chemistry, University of Helsinki, Helsinki, Finland.
authors.forename: Susanna
authors.initials: S
authors.lastname: Lintula
authors.affiliation: Department of Clinical Chemistry, University of Helsinki, Helsinki, Finland.
authors.forename: Kristina
authors.initials: K
authors.lastname: Hotakainen
authors.affiliation: Department of Obstetrics and Gynecology, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Heli
authors.initials: H
authors.lastname: Nevanlinna
authors.affiliation: Department of Hematology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Hokland
authors.affiliation: Department of Pathology, The Laboratory of Helsinki University Central Hospital (HUSLAB), Helsinki University Central Hospital and Medicum, University of Helsinki, Helsinki, Finland.
authors.forename: Tom
authors.initials: T
authors.lastname: Böhling
authors.affiliation: Department of Pathology, The Laboratory of Helsinki University Central Hospital (HUSLAB), Helsinki University Central Hospital and Medicum, University of Helsinki, Helsinki, Finland.
authors.forename: Ralf
authors.initials: R
authors.lastname: Bützow
authors.affiliation: Department of Pathology, Jyväskylä Central Hospital, Jyväskylä, Finland.
authors.forename: Jan
authors.initials: J
authors.lastname: Böhm
authors.affiliation: Department of Surgery, Jyväskylä Central Hospital and University of Eastern Finland, Jyväskylä, Finland.
authors.forename: Jukka-Pekka
authors.initials: JP
authors.lastname: Mecklin
authors.affiliation: Department of Surgery, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Järvinen
authors.affiliation: Hematology Research Unit Helsinki, Department of Medicine, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Kontro
authors.affiliation: Institute of Biosciences and Medical Technology - BioMediTech and Fimlab Laboratories, University of Tampere and Tampere University Hospital, Tampere, Finland.
authors.forename: Tapio
authors.initials: T
authors.lastname: Visakorpi
authors.affiliation: Genome-Scale Biology Research Program and Department of Pathology, University of Helsinki, Helsinki, Finland.
authors.forename: Jussi
authors.initials: J
authors.lastname: Taipale
authors.affiliation: Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors.forename: Markku
authors.initials: M
authors.lastname: Varjosalo
authors.affiliation: Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Boyer
authors.affiliation: Genome-Scale Biology Research Program and Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland.
authors.forename: Pia
authors.initials: P
authors.lastname: Vahteristo
mesh_terms: D000368:Aged; D063646:Carcinogenesis / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D005260:Female; D006801:Humans; D007889:Leiomyoma / Q000235:genetics / Q000473:pathology; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D056892:Mediator Complex / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000235:genetics / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics; D014594:Uterine Neoplasms / Q000235:genetics / Q000473:pathology
chemical_list: C460107:MED12 protein, human; D056892:Mediator Complex; D014157:Transcription Factors
keywords: CDK8; MED12; Mediator; kinase activity; prostate cancer; uterine leiomyoma