title: Enhanced cAMP-stimulated protein kinase A activity in human fibrolamellar hepatocellular carcinoma.
abstract: Fibrolamellar hepatocellular carcinoma (FL-HCC) affects children without underlying liver disease. A consistent mutation in FL-HCCs leads to fusion of the genes encoding a heat shock protein (DNAJB1) and the catalytic subunit of protein kinase A (PRKACA). We sought to characterize the resultant chimeric protein and its effects in FL-HCC.
  
  
  
  The expression pattern and subcellular localization of protein kinase A (PKA) subunits in FL-HCCs were compared to paired normal livers by quantitative polymerase chain reaction (qPCR), immunoblotting, and immunofluorescence. PKA activity was measured by radioactive kinase assay, and we determined whether the FL-HCC mutation is present in other primary liver tumors.
  
  
  
  The fusion transcript and chimeric protein were detected exclusively in FL-HCCs. DNAJB1-PRKACA was expressed 10-fold higher than the wild-type PRKACA transcript, resulting in overexpression of the mutant protein in tumors. Consequently, FL-HCCs possess elevated cAMP-stimulated PKA activity compared to normal livers, despite similar Kms between the mutant and wild-type kinases.
  
  
  
  FL-HCCs in children and young adults uniquely overexpress DNAJB1-PRKACA, which results in elevated cAMP-dependent PKA activity. These data suggest that aberrant PKA signaling contributes to liver tumorigenesis.
authors.affiliation: Department of Surgery, University of Washington, Seattle, Washington.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Riggle
authors.affiliation: Department of Surgery, University of Washington, Seattle, Washington.|Northwest Liver Research Program, University of Washington, Seattle, Washington.|Department of Pathology, University of Washington, Seattle, Washington.|Division of General and Thoracic Surgery, Seattle Children's Hospital, Seattle, Washington.
authors.forename: Kimberly J
authors.initials: KJ
authors.lastname: Riehle
authors.affiliation: Department of Surgery, University of Washington, Seattle, Washington.
authors.forename: Heidi L
authors.initials: HL
authors.lastname: Kenerson
authors.affiliation: Howard Hughes Medical Institute, University of Washington, Seattle, Washington.|Department of Pharmacology, University of Washington, Seattle, Washington.
authors.forename: Rigney
authors.initials: R
authors.lastname: Turnham
authors.affiliation: Howard Hughes Medical Institute, University of Washington, Seattle, Washington.|Department of Biomolecular Science, Fukushima University School of Medicine, Fukushima, Japan.
authors.forename: Miwako K
authors.identifier: 0000-0002-5920-3596
authors.initials: MK
authors.lastname: Homma
authors.affiliation: Department of Surgery, University of Washington, Seattle, Washington.
authors.forename: Machiko
authors.initials: M
authors.lastname: Kazami
authors.affiliation: Howard Hughes Medical Institute, University of Washington, Seattle, Washington.|Department of Pharmacology, University of Washington, Seattle, Washington.
authors.forename: Bret
authors.initials: B
authors.lastname: Samelson
authors.affiliation: Department of Surgery, University of Washington, Seattle, Washington.
authors.forename: Renay
authors.initials: R
authors.lastname: Bauer
authors.affiliation: Department of Pharmacology, University of Washington, Seattle, Washington.
authors.forename: G Stanley
authors.initials: GS
authors.lastname: McKnight
authors.affiliation: Howard Hughes Medical Institute, University of Washington, Seattle, Washington.|Department of Pharmacology, University of Washington, Seattle, Washington.
authors.forename: John D
authors.initials: JD
authors.lastname: Scott
authors.affiliation: Department of Surgery, University of Washington, Seattle, Washington.|Northwest Liver Research Program, University of Washington, Seattle, Washington.
authors.forename: Raymond S
authors.initials: RS
authors.lastname: Yeung
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000201:enzymology* / Q000235:genetics; D020134:Catalytic Domain; D000242:Cyclic AMP / Q000378:metabolism; D054751:Cyclic AMP-Dependent Protein Kinase Catalytic Subunits / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008103:Liver Cirrhosis / Q000150:complications; D008113:Liver Neoplasms / Q000201:enzymology* / Q000235:genetics; D008207:Lymphatic Metastasis; D009154:Mutation; D009364:Neoplasm Recurrence, Local
chemical_list: D015124:8-Bromo Cyclic Adenosine Monophosphate; C044258:8-chloro-cyclic adenosine monophosphate; D000242:Cyclic AMP; D054751:Cyclic AMP-Dependent Protein Kinase Catalytic Subunits; C517757:PRKACA protein, human