title: Effects of AKT inhibitor therapy in response and resistance to BRAF inhibition in melanoma.
abstract: BACKGROUND
  The clinical use of BRAF inhibitors for treatment of metastatic melanoma is limited by the development of drug resistance. In this study we investigated whether co-targeting the MAPK and the PI3K-AKT pathway can prevent emergence of resistance or provide additional growth inhibitory effects in vitro.
  
  
  METHODS
  Anti-tumor effects of the combination of the BRAF inhibitor (BRAFi) dabrafenib and GSK2141795B (AKTi) in a panel of 23 BRAF mutated melanoma cell lines were evaluated on growth inhibition by an ATP-based luminescent assay, on cell cycle and apoptosis by flow cytometry and on cell signaling by western blot. Moreover, we investigated the possibilities of delaying or reversing resistance or achieving further growth inhibition by combining AKTi with dabrafenib and/or the MEK inhibitor (MEKi) trametinib by using long term cultures.
  
  
  RESULTS
  More than 40% of the cell lines, including PTEN-/- and AKT mutants showed sensitivity to AKTi (IC50 < 1.5 μM). The combination of dabrafenib and AKTi synergistically potentiated growth inhibition in the majority of cell lines with IC50 > 5 nM dabrafenib. Combinatorial treatment induced apoptosis only in cell lines sensitive to AKTi. In long term cultures of a PTEN-/- cell line, combinatorial treatment with the MAPK inhibitors, dabrafenib and trametinib, and AKTi markedly delayed the emergence of drug resistance. Moreover, combining AKTi with the MAPK inhibitors from the beginning provided superior growth inhibitory effects compared to addition of AKTi upon development of resistance to MAPK inhibitors in this particular cell line.
  
  
  CONCLUSIONS
  AKTi combined with BRAFi-based therapy may benefit patients with tumors harboring BRAF mutations and particularly PTEN deletions or AKT mutations.
authors.forename: Amanda
authors.initials: A
authors.lastname: Lassen
authors.forename: Mohammad
authors.initials: M
authors.lastname: Atefi
authors.forename: Lidia
authors.initials: L
authors.lastname: Robert
authors.forename: Deborah Jl
authors.initials: DJ
authors.lastname: Wong
authors.forename: Michael
authors.initials: M
authors.lastname: Cerniglia
authors.forename: Begonya
authors.initials: B
authors.lastname: Comin-Anduix
authors.affiliation: Department of Medicine, Division of Hematology-Oncology, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA. aribas@mednet.ucla.edu.
authors.forename: Antoni
authors.initials: A
authors.lastname: Ribas
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors; D008545:Melanoma / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D009154:Mutation; D010091:Oximes / Q000008:administration & dosage; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors / Q000235:genetics*; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics*; D011728:Pyridones / Q000008:administration & dosage; D011744:Pyrimidinones / Q000008:administration & dosage; D015398:Signal Transduction; D023041:Xenograft Model Antitumor Assays
chemical_list: D007093:Imidazoles; D010091:Oximes; D047428:Protein Kinase Inhibitors; D011728:Pyridones; D011744:Pyrimidinones; C560077:trametinib; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D051057:Proto-Oncogene Proteins c-akt; D020930:MAP Kinase Kinase Kinases; C561627:dabrafenib
references.citation: J Transl Med. 2011 May 24;9:76
references.pmid: 21609436
references.citation: N Engl J Med. 2010 Aug 26;363(9):809-19
references.pmid: 20818844
references.citation: Sci Transl Med. 2013 Jul 31;5(196):196ra98
references.pmid: 23903755
references.citation: Front Biosci. 2005 Sep 01;10:2986-3001
references.pmid: 15970553
references.citation: PLoS One. 2012;7(8):e42598
references.pmid: 22880048
references.citation: Nature. 2010 Dec 16;468(7326):973-7
references.pmid: 21107323
references.citation: Nature. 2011 Nov 23;480(7377):387-90
references.pmid: 22113612
references.citation: Cancer Discov. 2014 Jan;4(1):94-109
references.pmid: 24265153
references.citation: Oncogene. 2008 Sep 18;27(41):5527-41
references.pmid: 18794886
references.citation: Cancer Cell. 2010 Dec 14;18(6):683-95
references.pmid: 21156289
references.citation: Nat Commun. 2012 Mar 06;3:724
references.pmid: 22395615
references.citation: Cancer Discov. 2013 Feb;3(2):158-67
references.pmid: 23242808
references.citation: Lancet. 2012 Jul 28;380(9839):358-65
references.pmid: 22735384
references.citation: Mol Cancer Ther. 2006 May;5(5):1136-44
references.pmid: 16731745
references.citation: J Mol Med (Berl). 2012 Jun;90(6):667-79
references.pmid: 22215152
references.citation: N Engl J Med. 2012 Feb 23;366(8):707-14
references.pmid: 22356324
references.citation: Br J Dermatol. 2007 Jun;156(6):1204-13
references.pmid: 17388918
references.citation: J Invest Dermatol. 2012 Jul;132(7):1850-9
references.pmid: 22437314
references.citation: Nature. 1994 Sep 22;371(6495):346-7
references.pmid: 8090205
references.citation: Clin Cancer Res. 2012 Apr 15;18(8):2316-25
references.pmid: 22261800
references.citation: J Clin Invest. 2008 Sep;118(9):3065-74
references.pmid: 18725988
references.citation: J Clin Oncol. 2011 Aug 1;29(22):3085-96
references.pmid: 21383288
references.citation: J Invest Dermatol. 2008 Aug;128(8):2013-23
references.pmid: 18323781
references.citation: J Cell Biol. 2004 Jul 19;166(2):213-23
references.pmid: 15249583
references.citation: Cancer Res. 2010 Nov 1;70(21):8736-47
references.pmid: 20959481
references.citation: Biochem Pharmacol. 2011 Aug 1;82(3):201-9
references.pmid: 21635872
references.citation: Adv Enzyme Regul. 2006;46:249-79
references.pmid: 16854453
references.citation: Cancer Res. 2011 Aug 1;71(15):5067-74
references.pmid: 21803746
references.citation: Biochem Soc Trans. 2012 Feb;40(1):139-46
references.pmid: 22260680
references.citation: J Transl Med. 2010 Apr 20;8:39
references.pmid: 20406486
references.citation: Pigment Cell Melanoma Res. 2012 Mar;25(2):248-58
references.pmid: 22171948
references.citation: Nature. 2010 Dec 16;468(7326):968-72
references.pmid: 21107320
references.citation: J Biol Chem. 1998 Dec 11;273(50):33533-9
references.pmid: 9837934
references.citation: Cancer Discov. 2014 Jan;4(1):80-93
references.pmid: 24265155
references.citation: Cancer Discov. 2014 Jan;4(1):61-8
references.pmid: 24265154
references.citation: Nature. 2010 Sep 30;467(7315):596-9
references.pmid: 20823850
references.citation: Semin Cell Dev Biol. 2004 Apr;15(2):161-70
references.pmid: 15209375
references.citation: Proc Natl Acad Sci U S A. 2009 Dec 1;106(48):20411-6
references.pmid: 19915144
references.citation: Cancer Res. 2012 Feb 15;72(4):969-78
references.pmid: 22205714
references.citation: N Engl J Med. 2012 Nov;367(18):1694-703
references.pmid: 23020132
references.citation: PLoS One. 2011;6(12):e28973
references.pmid: 22194965