title: An unusual H-Ras mutant isolated from a human multiple myeloma line leads to transformation and factor-independent cell growth.
abstract: Multiple myeloma (MM) is an incurable plasma cell malignancy. To investigate biochemical lesions associated with MM, we constructed an expression cDNA library from the OPM-2 human myeloma line. A highly transforming H-Ras mutant was identified by transfection analysis using NIH 3T3 cells. DNA sequencing demonstrated a single-point mutation at position 117 located in the guanine nucleotide-binding site resulting in a lysine-to-glutamic acid substitution. This mutant, H-Ras (K117E), was found to be constitutively activated in terms of GTP binding. We compared the biological effects of H-Ras (K117E) and H-Ras (G12V) in 32D murine hematopoietic progenitor cells. Whereas both Ras proteins are constitutively activated, 32D cells expressing H-Ras (G12V) are still dependent on IL-3 for survival and proliferation while cells carrying H-Ras (K117E) become IL-3 independent. Similar experiments conducted with the B9 line, an IL-6-dependent hybridoma, also demonstrated that B9/H-Ras (K117E) became IL-6-independent. Expression of H-Ras (K117E) in the human IL-6-dependent ANBL-6 myeloma line resulted in enhanced proliferation at suboptimal concentrations of IL-6. These observations suggest that H-Ras mutations at the binding site for the GTP nucleotide ring structure may also represent activating lesions and have additional biological effects when compared to previously described Ras mutants.
authors.affiliation: Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Chun
authors.initials: C
authors.lastname: Crowder
authors.forename: Eugene
authors.initials: E
authors.lastname: Kopantzev
authors.forename: Kevin
authors.initials: K
authors.lastname: Williams
authors.forename: Carol
authors.initials: C
authors.lastname: Lengel
authors.forename: Toru
authors.initials: T
authors.lastname: Miki
authors.forename: Stuart
authors.initials: S
authors.lastname: Rudikoff
mesh_terms: D000818:Animals; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D011905:Genes, ras / Q000502:physiology; D006133:Growth Substances / Q000502:physiology; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D051379:Mice; D009101:Multiple Myeloma / Q000235:genetics*; D009154:Mutation; D014407:Tumor Cells, Cultured
chemical_list: D006133:Growth Substances; D006160:Guanosine Triphosphate