title: Receptor tyrosine kinase and downstream signalling analysis in diffuse malignant peritoneal mesothelioma.
abstract: Our aim was to assess the activation profile of EGFR, PDGFRB and PDGFRA receptor tyrosine kinases (RTK) and their downstream effectors in a series of cryopreserved diffuse malignant peritoneal mesothelioma (DMPM) surgical specimens to discover the targets for drug inhibition. We also made a complementary analysis of the cytotoxic effects of some kinase inhibitors on the proliferation of the human peritoneal mesothelioma STO cell line. We found the expression/phosphorylation of EGFR and PDGFRB in most of the tumours, and PDGFRA activation in half. The expression of the cognate ligands TGF-α, PDGFB and PDGFA in the absence of RTK mutation and amplification suggested the presence of an autocrine/paracrine loop. There was also evidence of EGFR and PDGFRB co-activation. RTK downstream signalling analysis demonstrated the activation/expression of ERK1/2, AKT and mTOR, together with S6 and 4EBP1, in almost all the DMPMs. No KRAS/BRAF mutations, PI3KCA mutations/amplifications or PTEN inactivation were observed. Real-time polymerase chain reaction revealed the decreased expression of TSC1 c-DNA in half of the tumours. In vitro cytotoxicity studies showed the STO cell line to be resistant to gefitinib and sensitive to sequential treatment with RAD001 and sorafenib; these findings were consistent with the presence of the KRAS mutation G12D in these cells although it was not detectable in the original tumour. Our results highlight the ligand-dependent activation and co-activation of EGFR and PDGFRB, as well as a connection between these activated RTKs and the downstream mTOR pathway, thus supporting the role of combined treatment with RTK and mTOR inhibitors in DMPM.
authors.affiliation: Experimental Molecular Pathology, Department of Pathology, Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian 1, 20133 Milano, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Perrone
authors.forename: Genny
authors.initials: G
authors.lastname: Jocollè
authors.forename: Marzia
authors.initials: M
authors.lastname: Pennati
authors.forename: Marcello
authors.initials: M
authors.lastname: Deraco
authors.forename: Dario
authors.initials: D
authors.lastname: Baratti
authors.forename: Silvia
authors.initials: S
authors.lastname: Brich
authors.forename: Marta
authors.initials: M
authors.lastname: Orsenigo
authors.forename: Eva
authors.initials: E
authors.lastname: Tarantino
authors.forename: Cinzia
authors.initials: C
authors.lastname: De Marco
authors.forename: Claudia
authors.initials: C
authors.lastname: Bertan
authors.forename: Antonello
authors.initials: A
authors.lastname: Cabras
authors.forename: Rossella
authors.initials: R
authors.lastname: Bertulli
authors.forename: Marco Alessandro
authors.initials: MA
authors.lastname: Pierotti
authors.forename: Nadia
authors.initials: N
authors.lastname: Zaffaroni
authors.forename: Silvana
authors.initials: S
authors.lastname: Pilotti
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis; D004252:DNA Mutational Analysis; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D019942:Genes, p16; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008654:Mesothelioma / Q000201:enzymology* / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D010997:Pleural Neoplasms / Q000201:enzymology* / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000378:metabolism; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism
chemical_list: D066246:ErbB Receptors; D020794:Receptor Protein-Tyrosine Kinases; D020796:Receptor, Platelet-Derived Growth Factor alpha; D020797:Receptor, Platelet-Derived Growth Factor beta