title: Inhibition of mutant GNAQ signaling in uveal melanoma induces AMPK-dependent autophagic cell death.
abstract: Oncogenic mutations in GNAQ and GNA11 genes are found in 80% of uveal melanoma. These mutations result in the activation of the RAF/MEK signaling pathway culminating in the stimulation of ERK1/2 mitogen-activated protein kinases. In this study, using a siRNA strategy, we show that mutant GNAQ signals to both MEK and AKT, and that combined inhibition of these pathways with the MEK inhibitor selumetinib (AZD6244) and the AKT inhibitor MK2206 induced a synergistic decrease in cell viability. This effect was genotype dependent as autophagic markers like beclin1 and LC3 were induced in GNAQ-mutant cells, whereas apoptosis was the mechanism of cell death of BRAF-mutant cells, and cells without either mutation underwent cell-cycle arrest. The inhibition of MEK/ATK pathways induced activation of AMP-activated protein kinase (AMPK) in the GNAQ-mutant cells. The downregulation of AMPK by siRNA or its inhibition with compound C did not rescue the cells from autophagy, rather they died by apoptosis, defining AMPK as a key regulator of mutant GNAQ signaling and a switch between autophagy and apoptosis. Furthermore, this combination treatment was effective in inhibiting tumor growth in xenograft mouse models. These findings suggest that inhibition of MEK and AKT may represent a promising approach for targeted therapy of patients with uveal melanoma.
authors: Laboratory of New Drug Development, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA. ambrosig@mskcc.org
authors: Grazia
authors: G
authors: Ambrosini
authors: Elgilda
authors: E
authors: Musi
authors: Alan L
authors: AL
authors: Ho
authors: Elisa
authors: E
authors: de Stanchina
authors: Gary K
authors: GK
authors: Schwartz
mesh_terms: D000818:Animals; D001343:Autophagy / Q000235:genetics*; D001562:Benzimidazoles / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics* / Q000378:metabolism*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D055785:Gene Knockdown Techniques; D006575:Heterocyclic Compounds, 3-Ring / Q000494:pharmacology; D006801:Humans; D008297:Male; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction; D047368:Tumor Burden / Q000187:drug effects; D014604:Uveal Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D023041:Xenograft Model Antitumor Assays; D000098943:Uveal Melanoma
chemical_list: C517975:AZD 6244; D001562:Benzimidazoles; C554061:GNAQ protein, human; D044385:GTP-Binding Protein alpha Subunits; D006575:Heterocyclic Compounds, 3-Ring; C548887:MK 2206; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D043802:GTP-Binding Protein alpha Subunits, Gq-G11