title: Multi-level suppression of receptor-PI3K-mTORC1 by fatty acid synthase inhibitors is crucial for their efficacy against ovarian cancer cells.
abstract: Receptor-PI3K-mTORC1 signaling and fatty acid synthase (FASN)-regulated lipid biosynthesis harbor numerous drug targets and are molecularly connected. We hypothesize that unraveling the mechanisms of pathway cross-talk will be useful for designing novel co-targeting strategies for ovarian cancer (OC). The impact of receptor-PI3K-mTORC1 onto FASN is already well-characterized. However, reverse actions-from FASN towards receptor-PI3K-mTORC1-are still elusive. We show that FASN-blockade impairs receptor-PI3K-mTORC1 signaling at multiple levels. Thin-layer chromatography and MALDI-MS/MS reveals that FASN-inhibitors (C75, G28UCM) augment polyunsaturated fatty acids and diminish signaling lipids diacylglycerol (DAG) and phosphatidylinositol 3,4,5-trisphosphate (PIP3) in OC cells (SKOV3, OVCAR-3, A2780, HOC-7). Western blotting and micropatterning demonstrate that FASN-blockers impair phosphorylation/expression of EGF-receptor/ERBB/HER and decrease GRB2-EGF-receptor recruitment leading to PI3K-AKT suppression. FASN-inhibitors activate stress response-genes HIF-1α-REDD1 (RTP801/DIG2/DDIT4) and AMPKα causing mTORC1- and S6-repression. We conclude that FASN-inhibitor-mediated blockade of receptor-PI3K-mTORC1 occurs due to a number of distinct but cooperating processes. Moreover, decrease of PI3K-mTORC1 abolishes cross-repression of MEK-ERK causing ERK activation. Consequently, the MEK-inhibitor selumetinib/AZD6244, in contrast to the PI3K/mTOR-inhibitor dactolisib/NVP-BEZ235, increases growth inhibition when given together with a FASN-blocker. We are the first to provide deep insight on how FASN-inhibition blocks ERBB-PI3K-mTORC1 activity at multiple molecular levels. Moreover, our data encourage therapeutic approaches using FASN-antagonists together with MEK-ERK-inhibitors.
authors.affiliation: Division of Oncology, Department of Medicine I, Medical University Vienna, Vienna, Austria.|Comprehensive Cancer Center, Medical University Vienna, Vienna, Austria.
authors.forename: Renate
authors.initials: R
authors.lastname: Wagner
authors.affiliation: Comprehensive Cancer Center, Medical University Vienna, Vienna, Austria.|Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria.|Center for Biomarker Research in Medicine, Graz, Austria.
authors.forename: Gerald
authors.initials: G
authors.lastname: Stübiger
authors.affiliation: Division of Oncology, Department of Medicine I, Medical University Vienna, Vienna, Austria.|Comprehensive Cancer Center, Medical University Vienna, Vienna, Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Veigel
authors.affiliation: Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria.|Center for Biomarker Research in Medicine, Graz, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Wuczkowski
authors.affiliation: University of Applied Sciences Upper Austria, School of Engineering and Environmental Sciences, Wels, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Lanzerstorfer
authors.affiliation: University of Applied Sciences Upper Austria, School of Engineering and Environmental Sciences, Wels, Austria.
authors.forename: Julian
authors.initials: J
authors.lastname: Weghuber
authors.affiliation: Department of Biosciences, School of Health Sciences and Social Care, Brunel University London, Uxbridge, UK.
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Karteris
authors.affiliation: Division of Oncology, Department of Medicine I, Medical University Vienna, Vienna, Austria.|Comprehensive Cancer Center, Medical University Vienna, Vienna, Austria.
authors.forename: Karin
authors.initials: K
authors.lastname: Nowikovsky
authors.affiliation: Division of Oncology, Department of Medicine I, Medical University Vienna, Vienna, Austria.|Comprehensive Cancer Center, Medical University Vienna, Vienna, Austria.
authors.forename: Nastasia
authors.initials: N
authors.lastname: Wilfinger-Lutz
authors.affiliation: Department of Obstetrics/Gynecology, Medical University Vienna, Vienna, Austria.
authors.forename: Christian F
authors.initials: CF
authors.lastname: Singer
authors.affiliation: Department of Medical Oncology, Hospital Universitario La Princesa and Spanish National Cancer Research Center (CNIO), Clinical Research Program, Madrid, Spain.
authors.forename: Ramón
authors.initials: R
authors.lastname: Colomer
authors.affiliation: Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Bellinda
authors.initials: B
authors.lastname: Benhamú
authors.affiliation: Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: María Luz
authors.initials: ML
authors.lastname: López-Rodríguez
authors.affiliation: Comprehensive Cancer Center, Medical University Vienna, Vienna, Austria.|Division of Hematology and Hemostaseology, Department of Medicine I, Medical University Vienna, Vienna, Austria.|Ludwig Boltzmann Cluster Oncology, Medical University Vienna, Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Valent
authors.affiliation: Division of Oncology, Department of Medicine I, Medical University Vienna, Vienna, Austria.|Comprehensive Cancer Center, Medical University Vienna, Vienna, Austria.|Ludwig Boltzmann Cluster Oncology, Medical University Vienna, Vienna, Austria.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Grunt
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D064429:Fatty Acid Synthases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005260:Female; D006801:Humans; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D064429:Fatty Acid Synthases; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D058570:TOR Serine-Threonine Kinases
keywords: AMPK; REDD1; fatty acid synthase (FASN); lipids; mTORC1