title: MEK/ERK inhibitor U0126 affects in vitro and in vivo growth of embryonal rhabdomyosarcoma.
abstract: We reported previously that the disruption of c-Myc through mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) inhibition blocks the expression of the transformed phenotype in the embryonal rhabdomyosarcoma (ERMS) cell line (RD), thereby inducing myogenic differentiation in vitro. In this article, we investigate whether MEK/ERK inhibition, by the MEK/ERK inhibitor U0126, affects c-Myc protein level and growth of RMS tumor in an in vivo xenograft model. U0126 significantly reduced RMS tumor growth in RD cell line-xenotransplanted mice. Immunobiochemical and immunohistochemical analysis showed (a) phospho-active ERK levels were reduced by U0126 therapy and unaltered in normal tissues, (b) phospho-Myc and c-Myc was reduced commensurate with phospho-ERK inhibition, and (c) reduction in Ki-67 and endothelial (CD31) marker expression. These results indicate that MEK/ERK inhibition affects growth and angiogenic signals in tumor. The RD-M1 cultured xenograft tumor-derived cell line and the ERMS cell line TE671 responded to U0126 by arresting growth, down-regulating c-Myc, and initiating myogenesis. All these results suggest a tight correlation of MEK/ERK inhibition with c-Myc down-regulation and arrest of tumor growth. Thus, MEK inhibitors may be investigated for a signal transduction-based targeting of the c-Myc as a therapeutic strategy in ERMS.
authors.affiliation: Department of Experimental Medicine, University of L'Aquila, Via Vetoio Coppito II, 67100 L'Aquila, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Marampon
authors.forename: Gianluca
authors.initials: G
authors.lastname: Bossi
authors.forename: Carmela
authors.initials: C
authors.lastname: Ciccarelli
authors.forename: Agnese
authors.initials: A
authors.lastname: Di Rocco
authors.forename: Ada
authors.initials: A
authors.lastname: Sacchi
authors.forename: Richard G
authors.initials: RG
authors.lastname: Pestell
authors.forename: Bianca M
authors.initials: BM
authors.lastname: Zani
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D002070:Butadienes / Q000494:pharmacology* / Q000627:therapeutic use; D049109:Cell Proliferation / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors*; D051379:Mice; D008819:Mice, Nude; D019042:Muscle Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D009570:Nitriles / Q000494:pharmacology* / Q000627:therapeutic use; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D018233:Rhabdomyosarcoma, Embryonal / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D002070:Butadienes; D004791:Enzyme Inhibitors; C489427:MYC protein, human; D009570:Nitriles; D016271:Proto-Oncogene Proteins c-myc; C113580:U 0126; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases