title: A recurrent activating PLCG1 mutation in cardiac angiosarcomas increases apoptosis resistance and invasiveness of endothelial cells.
abstract: Primary cardiac angiosarcomas are rare tumors with unfavorable prognosis. Pathogenic driver mutations are largely unknown. We therefore analyzed a collection of cases for genomic aberrations using SNP arrays and targeted next-generation sequencing (tNGS) of oncogenes and tumor-suppressor genes. Recurrent gains of chromosome 1q and a small region of chromosome 4 encompassing KDR and KIT were identified by SNP array analysis. Repeatedly mutated genes identified by tNGS were KDR with different nonsynonymous mutations, MLL2 with different nonsense mutations, and PLCG1 with a recurrent nonsynonymous mutation (R707Q) in the highly conserved autoinhibitory SH2 domain in three of 10 cases. PLCγ1 is usually activated by Y783 phosphorylation and activates protein kinase C and Ca(2+)-dependent second messengers, with effects on cellular proliferation, migration, and invasiveness. Ectopic expression of the PLCγ1-R707Q mutant in endothelial cells revealed reduced PLCγ1-Y783 phosphorylation with concomitant increased c-RAF/MEK/ERK1/2 phosphorylation, increased IP3 amounts, and increased Ca(2+)-dependent calcineurin activation compared with ectopic expressed PLCγ1-wild-type. Furthermore, cofilin, whose activation is associated with actin skeleton reorganization, showed decreased phosphorylation, and thus activation after expression of PLCγ1-R707Q compared with PLCγ1-wild-type. At the cellular level, expression of PLCγ1-R707Q in endothelial cells had no influence on proliferation rate, but increased apoptosis resistance and migration and invasiveness in in vitro assays. Together, these findings indicate that the PLCγ1-R707Q mutation causes constitutive activation of PLCγ1 and may represent an alternative way of activation of KDR/PLCγ1 signaling besides KDR activation in angiosarcomas, with implications for VEGF/KDR targeted therapies.
authors.affiliation: Department of Pathology, Justus-Liebig-University Giessen, Giessen, Germany.
authors.forename: Kristin
authors.initials: K
authors.lastname: Kunze
authors.affiliation: Institute for Pathology, St. Francis Hospital, Münster, Germany.
authors.forename: Tilmann
authors.initials: T
authors.lastname: Spieker
authors.affiliation: Department of Pathology, Justus-Liebig-University Giessen, Giessen, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Gamerdinger
authors.affiliation: Department of Pathology, Justus-Liebig-University Giessen, Giessen, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Nau
authors.affiliation: Department of Pathology, Justus-Liebig-University Giessen, Giessen, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Berger
authors.affiliation: Department of Pathology, Justus-Liebig-University Giessen, Giessen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dreyer
authors.affiliation: Department of Cardiothoracic Surgery, Division of Cardiac Surgery, University Hospital Münster, Münster, Germany.
authors.forename: Jürgen R
authors.initials: JR
authors.lastname: Sindermann
authors.affiliation: Department of Cardiothoracic Surgery, Division of Cardiac Surgery, University Hospital Münster, Münster, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hoffmeier
authors.affiliation: Department of Pathology, Justus-Liebig-University Giessen, Giessen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Gattenlöhner
authors.affiliation: Department of Pathology, Justus-Liebig-University Giessen, Giessen, Germany. Andreas.braeuninger@patho.med.uni-giessen.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bräuninger
mesh_terms: D017209:Apoptosis / Q000235:genetics; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006338:Heart Neoplasms / Q000235:genetics* / Q000473:pathology; D006394:Hemangiosarcoma / Q000235:genetics* / Q000473:pathology; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D009154:Mutation; D009361:Neoplasm Invasiveness / Q000235:genetics*; D051966:Phospholipase C gamma / Q000096:biosynthesis / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics; D018909:src Homology Domains / Q000235:genetics
chemical_list: D040301:Vascular Endothelial Growth Factor Receptor-2; C522157:PLCG1 protein, human; D051966:Phospholipase C gamma