title: BRAF inhibitor resistance mediated by the AKT pathway in an oncogenic BRAF mouse melanoma model.
abstract: BRAF (v-raf murine sarcoma viral oncogene homolog B) inhibitors elicit a transient anti-tumor response in ∼ 80% of BRAF(V600)-mutant melanoma patients that almost uniformly precedes the emergence of resistance. Here we used a mouse model of melanoma in which melanocyte-specific expression of Braf(V618E) (analogous to the human BRAF(V600E) mutation) led to the development of skin hyperpigmentation and nevi, as well as melanoma formation with incomplete penetrance. Sleeping Beauty insertional mutagenesis in this model led to accelerated and fully penetrant melanomagenesis and synchronous tumor formation. Treatment of Braf(V618E) transposon mice with the BRAF inhibitor PLX4720 resulted in tumor regression followed by relapse. Analysis of transposon insertions identified eight genes including Braf, Mitf, and ERas (ES-cell expressed Ras) as candidate resistance genes. Expression of ERAS in human melanoma cell lines conferred resistance to PLX4720 and induced hyperphosphorylation of AKT (v-akt murine thymoma viral oncogene homolog 1), a phenotype reverted by combinatorial treatment with PLX4720 and the AKT inhibitor MK2206. We show that ERAS expression elicits a prosurvival signal associated with phosphorylation/inactivation of BAD, and that the resistance of hepatocyte growth factor-treated human melanoma cells to PLX4720 can be reverted by treatment with the BAD-like BH3 mimetic ABT-737. Thus, we define a role for the AKT/BAD pathway in resistance to BRAF inhibition and illustrate an in vivo approach for finding drug resistance genes.
authors.affiliation: Experimental Cancer Genetics and Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom;
authors.forename: Daniele
authors.initials: D
authors.lastname: Perna
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom;
authors.forename: Florian A
authors.initials: FA
authors.lastname: Karreth
authors.affiliation: Experimental Cancer Genetics and.
authors.forename: Alistair G
authors.initials: AG
authors.lastname: Rust
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom;
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Perez-Mancera
authors.affiliation: Experimental Cancer Genetics and.
authors.forename: Mamunur
authors.initials: M
authors.lastname: Rashid
authors.affiliation: Cancer Genome Project, Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom; European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, Cambridge CB10 1SA, United Kingdom;
authors.forename: Francesco
authors.initials: F
authors.lastname: Iorio
authors.affiliation: Cancer Genome Project, Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom;
authors.forename: Constantine
authors.initials: C
authors.lastname: Alifrangis
authors.affiliation: University of Edinburgh Division of Pathology, Edinburgh Cancer Research Centre, Institute of Genetics & Molecular Medicine, Western General Hospital, Edinburgh, EH4 2XR, United Kingdom;
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Arends
authors.affiliation: Department of Dermatology, Yale University, New Haven, CT 06520;
authors.forename: Marcus W
authors.initials: MW
authors.lastname: Bosenberg
authors.affiliation: Plexxikon Inc., Berkeley, CA 94710; and.
authors.forename: Gideon
authors.initials: G
authors.lastname: Bollag
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724 dtuveson@cshl.edu da1@sanger.ac.uk.
authors.forename: David A
authors.initials: DA
authors.lastname: Tuveson
authors.affiliation: Experimental Cancer Genetics and dtuveson@cshl.edu da1@sanger.ac.uk.
authors.forename: David J
authors.initials: DJ
authors.lastname: Adams
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D015139:Blotting, Southern; D015153:Blotting, Western; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000235:genetics / Q000502:physiology*; D053595:Embryonic Stem Cells / Q000378:metabolism; D059472:Exome / Q000235:genetics; D056726:Genetic Association Studies; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007211:Indoles / Q000494:pharmacology; D008545:Melanoma / Q000188:drug therapy* / Q000378:metabolism; D051379:Mice; D016296:Mutagenesis; D015689:Oncogene Protein p21(ras) / Q000378:metabolism*; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D013449:Sulfonamides / Q000494:pharmacology; D019895:Transposases / Q000378:metabolism; D051025:bcl-Associated Death Protein / Q000378:metabolism
chemical_list: C494820:Bad protein, mouse; C474774:ERas protein, human; D007211:Indoles; C528407:PLX 4720; D013449:Sulfonamides; D051025:bcl-Associated Death Protein; D017228:Hepatocyte Growth Factor; C514862:Akt1 protein, mouse; C482120:Braf protein, mouse; D048493:Proto-Oncogene Proteins B-raf; D051057:Proto-Oncogene Proteins c-akt; D019895:Transposases; C494471:sleeping beauty transposase, human; D015689:Oncogene Protein p21(ras)
keywords: BRAF inhibitors; drug resistance; melanoma; mouse models