title: The Akt inhibitor MK2206 synergizes, but perifosine antagonizes, the BRAF(V600E) inhibitor PLX4032 and the MEK1/2 inhibitor AZD6244 in the inhibition of thyroid cancer cells.
abstract: OBJECTIVE
  The purpose of the study was to explore optimal combinations of currently actively developed drugs for dually targeting the Ras → Raf → MAPK kinase (MEK) → MAPK/ERK (MAPK) and the phosphatidylinositol 3-kinase/Akt pathways as effective treatments for thyroid cancer.
  
  
  METHODS
  We tested the combinations of the Akt inhibitors MK2206 or perifosine with the BRAF(V600E) inhibitor PLX4032 or the MEK1/2 inhibitor AZD6244 in thyroid cancer cells harboring both the BRAF(V600E) and PIK3CA mutations.
  
  
  RESULTS
  We found that MK2206 could potently, when used alone, and synergistically, when combined with either PLX4032 or AZD6244, inhibit thyroid cancer cell growth with all the combination index values lower than 1. Perifosine could potently inhibit thyroid cancer cell growth when used alone, but a strong antagonism occurred between this drug and PLX4032 or AZD6244 in the inhibition of thyroid cancer cell growth with all combination index values higher than 1. Combinations of MK2206 with PLX4032 or AZD6244 dramatically enhanced G1 cell cycle arrest induced by each drug alone. However, G2 cell cycle arrest uniquely induced by perifosine alone and G1 cell cycle arrest induced by PLX4032 or AZD6244 were both reversed by combination treatments, providing a mechanism for their antagonism. All these drugs could correspondingly inhibit the MAPK and phosphatidylinositol 3-kinase/Akt signalings, confirming their expected target effects.
  
  
  CONCLUSIONS
  We demonstrated, unexpectedly, opposite outcomes of MK2206 and perifosine in their combinational treatments with BRAF(V600E)/MEK inhibitors in thyroid cancer cells. The data may help appropriate selection of these prominent drugs for clinical trials of combination therapies for thyroid cancer.
authors.affiliation: Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology and Metabolism, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
authors.forename: Ruixin
authors.initials: R
authors.lastname: Liu
authors.forename: Dingxie
authors.initials: D
authors.lastname: Liu
authors.forename: Mingzhao
authors.initials: M
authors.lastname: Xing
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D001562:Benzimidazoles / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002277:Carcinoma / Q000188:drug therapy / Q000473:pathology*; D049109:Cell Proliferation / Q000187:drug effects*; D015536:Down-Regulation / Q000187:drug effects; D004336:Drug Antagonism; D004353:Drug Evaluation, Preclinical; D004357:Drug Synergism; D018698:Glutamic Acid / Q000235:genetics; D006575:Heterocyclic Compounds, 3-Ring / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007211:Indoles / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D050505:Mutant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D051058:Oncogene Protein v-akt / Q000037:antagonists & inhibitors; D010767:Phosphorylcholine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors / Q000235:genetics; D013449:Sulfonamides / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013964:Thyroid Neoplasms / Q000188:drug therapy / Q000473:pathology*; D014407:Tumor Cells, Cultured; D014633:Valine / Q000235:genetics; D000077484:Vemurafenib
chemical_list: C517975:AZD 6244; D001562:Benzimidazoles; D006575:Heterocyclic Compounds, 3-Ring; D007211:Indoles; C548887:MK 2206; D050505:Mutant Proteins; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D010767:Phosphorylcholine; D000077484:Vemurafenib; C105905:perifosine; D018698:Glutamic Acid; C482119:BRAF protein, human; D051058:Oncogene Protein v-akt; D048493:Proto-Oncogene Proteins B-raf; D014633:Valine
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