mk-2206 and Uveal-Neoplasms

Topics: Cell Line, Tumor; Cell Movement; Cell Proliferation; Female; G2 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Neoplastic; Heterocyclic Compounds, 3-Ring; Humans; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Melanoma; Middle Aged; Neovascularization, Pathologic; Proto-Oncogene Proteins c-akt; Rapamycin-Insensitive Companion of mTOR Protein; RNA, Small Interfering; Signal Transduction; Skin Neoplasms; Spheroids, Cellular; Survival Analysis; Uveal Neoplasms

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.

Topics: Animals; Autophagy; Benzimidazoles; Cell Line, Tumor; Cell Survival; Gene Knockdown Techniques; GTP-Binding Protein alpha Subunits; GTP-Binding Protein alpha Subunits, Gq-G11; Heterocyclic Compounds, 3-Ring; Humans; Male; Melanoma; Mice; Mitogen-Activated Protein Kinases; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Signal Transduction; Tumor Burden; Uveal Neoplasms; Xenograft Model Antitumor Assays

Inhibitors of B-Raf and MEK kinases hold promise for the management of cutaneous melanomas harboring BRAF mutations. BRAF mutations are rare in uveal melanomas (UMs), but somatic mutations in the G protein α subunits Gαq and Gα11 (encoded by GNAQ and GNA11, respectively) occur in a mutually exclusive pattern in ∼80% of UMs. The impact of B-Raf and MEK inhibitors on Gα-mutant UMs remains unknown.. The impact of the B-Raf inhibitor PLX4720, the MEK inhibitor AZD6244, and the Akt inhibitor MK2206 on UM cell lines was assessed with the use of cell viability, proliferation, and apoptosis assays and immunoblot analysis.. BRAF-mutant UM cells were sensitive to both PLX4720 and AZD6244, undergoing cell cycle arrest but not apoptosis. UM cells with a Gα-protein mutation (GNAQ or GNA11) were mildly sensitive to AZD6244 but completely resistant to PLX4720. In fact, PLX4720 paradoxically increased ERK phosphorylation in Gα-mutant UM cells. The combination of AZD6244 with PLX4720 had synergistic anticancer activity in BRAF-mutant cells but not in Gα-mutant cells. The Akt inhibitor MK2206 sensitized BRAF-mutant cells to both PLX4720 and AZD6244 and sensitized Gα-mutant cells to AZD6244 but did not overcome the resistance of the Gα-mutant cells to PLX4720.. The response of UM cells to inhibition of B-Raf, MEK, and Akt depends on their genotype. Future use of such targeted therapies in clinical trials of UM patients will require careful design and patient selection based on genotype to provide personalized and effective therapy.

Topics: Apoptosis; Benzimidazoles; Cell Line, Tumor; Cell Proliferation; Cell Survival; Genotype; Heterocyclic Compounds, 3-Ring; Humans; Immunoblotting; In Situ Nick-End Labeling; Indoles; MAP Kinase Kinase Kinases; Melanoma; Precision Medicine; Proto-Oncogene Proteins B-raf; Proto-Oncogene Proteins c-akt; Sulfonamides; Uveal Neoplasms