title: A mutation in the c-myc-IRES leads to enhanced internal ribosome entry in multiple myeloma: a novel mechanism of oncogene de-regulation.
abstract: The 5' untranslated region of the proto-oncogene c-myc contains an internal ribosome entry segment (IRES) (Nanbru et al., 1997; Stoneley et al., 1998) and thus c-myc protein synthesis can be initiated by a cap-independent as well as a cap-dependent mechanism (Stoneley et al., 2000). In cell lines derived from patients with multiple myeloma (MM) there is aberrant translational regulation of c-myc and this correlates with a C-T mutation in the c-myc-IRES (Paulin et al., 1996). RNA derived from the mutant IRES displays enhanced binding of protein factors (Paulin et al., 1998). Here we show that the same mutation is present in 42% of bone marrow samples obtained from patients with MM, but was not present in any of 21 controls demonstrating a strong correlation between this mutation and the disease. In a tissue culture based assay, the mutant version of the c-myc-IRES was more active in all cell types tested, but showed the greatest activity in a cell line derived from a patient with MM. Our data demonstrate that a single mutation in the c-myc-IRES is sufficient to cause enhanced initiation of translation via internal ribosome entry and represents a novel mechanism of oncogenesis.
authors.affiliation: Department of Biochemistry, University of Leicester, University Road, Leicester LE1 7RH, UK.
authors.forename: S A
authors.initials: SA
authors.lastname: Chappell
authors.forename: J P
authors.initials: JP
authors.lastname: LeQuesne
authors.forename: F E
authors.initials: FE
authors.lastname: Paulin
authors.forename: M L
authors.initials: ML
authors.lastname: deSchoolmeester
authors.forename: M
authors.initials: M
authors.lastname: Stoneley
authors.forename: R L
authors.initials: RL
authors.lastname: Soutar
authors.forename: S H
authors.initials: SH
authors.lastname: Ralston
authors.forename: M H
authors.initials: MH
authors.lastname: Helfrich
authors.forename: A E
authors.initials: AE
authors.lastname: Willis
mesh_terms: D020121:5' Untranslated Regions; D001483:Base Sequence; D001853:Bone Marrow / Q000502:physiology; D002460:Cell Line; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008969:Molecular Sequence Data; D009101:Multiple Myeloma / Q000235:genetics*; D017354:Point Mutation; D014176:Protein Biosynthesis; D000090063:Proto-Oncogene Mas; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012270:Ribosomes
chemical_list: D020121:5' Untranslated Regions; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D016271:Proto-Oncogene Proteins c-myc; D011994:Recombinant Proteins