title: Identification of cardiac glycoside molecules as inhibitors of c-Myc IRES-mediated translation.
abstract: Translation initiation is a fine-tuned process that plays a critical role in tumorigenesis. The use of small molecules that modulate mRNA translation provides tool compounds to explore the mechanism of translational initiation and to further validate protein synthesis as a potential pharmaceutical target for cancer therapeutics. This report describes the development and use of a click beetle, dual luciferase cell-based assay multiplexed with a measure of compound toxicity using resazurin to evaluate the differential effect of natural products on cap-dependent or internal ribosome entry site (IRES)-mediated translation initiation and cell viability. This screen identified a series of cardiac glycosides as inhibitors of IRES-mediated translation using, in particular, the oncogene mRNA c-Myc IRES. Treatment of c-Myc-dependent cancer cells with these compounds showed a decrease in c-Myc protein associated with a significant modulation of cell viability. These findings suggest that inhibition of IRES-mediated translation initiation may be a strategy to inhibit c-Myc-driven tumorigenesis.
authors.affiliation: Novartis Institutes for Biomedical Research, Basel, CH-4056 Switzerland. marie.didiot@gmail.com
authors.forename: Marie-Cecile
authors.initials: MC
authors.lastname: Didiot
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Hewett
authors.forename: Thibault
authors.initials: T
authors.lastname: Varin
authors.forename: Felix
authors.initials: F
authors.lastname: Freuler
authors.forename: Douglas
authors.initials: D
authors.lastname: Selinger
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Nick
authors.forename: Juergen
authors.initials: J
authors.lastname: Reinhardt
authors.forename: Alan
authors.initials: A
authors.lastname: Buckler
authors.forename: Vic
authors.initials: V
authors.lastname: Myer
authors.forename: Ansgar
authors.initials: A
authors.lastname: Schuffenhauer
authors.forename: Chantale T
authors.initials: CT
authors.lastname: Guy
authors.forename: Christian N
authors.initials: CN
authors.lastname: Parker
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D001681:Biological Assay; D002301:Cardiac Glycosides / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003529:Cymarine / Q000737:chemistry / Q000494:pharmacology; D004249:DNA Damage; D004353:Drug Evaluation, Preclinical; D017930:Genes, Reporter; D057809:HEK293 Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D014176:Protein Biosynthesis / Q000187:drug effects*; D011500:Protein Synthesis Inhibitors / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology*; D016271:Proto-Oncogene Proteins c-myc / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D002301:Cardiac Glycosides; D011500:Protein Synthesis Inhibitors; D016271:Proto-Oncogene Proteins c-myc; D042461:Vascular Endothelial Growth Factor A; D003529:Cymarine