title: Identification of unique MEK-dependent genes in GNAQ mutant uveal melanoma involved in cell growth, tumor cell invasion, and MEK resistance.
abstract: OBJECTIVE
  Metastatic uveal melanoma represents the most common intraocular malignancy with very poor prognosis and no effective treatments. Oncogenic mutations in the G-protein α-subunit q and 11 have been described in about 85% of uveal melanomas and confer constitutive activation. Multiple signaling pathways are induced as a consequence of GNAQ/11 activation, which include the MEK/ERK kinase cascade. We analyzed the transcriptional profile of cell lines treated with a mitogen-activated protein (MAP)/extracellular signal-regulated (ERK) kinase (MEK) inhibitor to identify gene targets of activated GNAQ and to evaluate the biologic importance of these genes in uveal melanoma.
  
  
  METHODS
  We conducted microarray analysis of uveal melanoma cell lines with GNAQ mutations treated with the MEK inhibitor selumetinib. For comparison, we used cells carrying BRAF(V600E) and cells without either mutation. Changes in the expression of selected genes were then confirmed by quantitative real-time PCR and immunoblotting.
  
  
  RESULTS
  We found that GNAQ mutant cells have a MEK-dependent transcriptional output and identified a unique set of genes that are downregulated by MEK inhibition, including the RNA helicase DDX21 and the cyclin-dependent kinase regulator CDK5R1 whereas Jun was induced. We provide evidence that these genes are involved in cell proliferation, tumor cell invasion, and drug resistance, respectively. Furthermore, we show that selumetinib treatment regulates the expression of these genes in tumor tissues of patients with metastatic GNAQ/11 mutant uveal melanoma.
  
  
  CONCLUSIONS
  Our findings define a subset of transcriptionally regulated genes by selumetinib in GNAQ mutant cells and provide new insights into understanding the biologic effect of MEK inhibition in this disease.
authors.affiliation: Laboratory of New Drug Development and Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York 10065, USA. ambrosig@mskcc.org
authors.forename: Grazia
authors.initials: G
authors.lastname: Ambrosini
authors.forename: Christine A
authors.initials: CA
authors.lastname: Pratilas
authors.forename: Li-Xuan
authors.initials: LX
authors.lastname: Qin
authors.forename: Madhavi
authors.initials: M
authors.lastname: Tadi
authors.forename: Oliver
authors.initials: O
authors.lastname: Surriga
authors.forename: Richard D
authors.initials: RD
authors.lastname: Carvajal
authors.forename: Gary K
authors.initials: GK
authors.lastname: Schwartz
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D001562:Benzimidazoles / Q000494:pharmacology / Q000627:therapeutic use; D045744:Cell Line, Tumor / Q000187:drug effects; D002465:Cell Movement; D049109:Cell Proliferation; D002470:Cell Survival / Q000187:drug effects; D017322:Clinical Trials, Phase II as Topic; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008545:Melanoma / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics* / Q000556:secondary; D020125:Mutation, Missense; D020411:Oligonucleotide Array Sequence Analysis; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D014158:Transcription, Genetic; D014604:Uveal Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics* / Q000473:pathology
chemical_list: C517975:AZD 6244; D000970:Antineoplastic Agents; D001562:Benzimidazoles; C554061:GNAQ protein, human; D044385:GTP-Binding Protein alpha Subunits; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D048031:JNK Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D043802:GTP-Binding Protein alpha Subunits, Gq-G11