title: Mutated RAS and constitutively activated Akt delineate distinct oncogenic pathways, which independently contribute to multiple myeloma cell survival.
abstract: We have recently shown that approximately half of primary multiple myeloma (MM) samples display constitutive Akt activity, which disposes them for sensitivity to Akt inhibition. The Akt pathway counts among the signaling conduits for oncogenic RAS and activating mutations of K- and N-RAS frequently occur in MM. We therefore analyzed the relation between RAS mutation and Akt dependency in biopsies and CD138-purified cells from MM patients (n = 65) and the function of oncogenic RAS for MM cell survival in a range of MM cell lines with differing RAS status. Whereas RAS mutations do not predict Akt dependency, oncogenic RAS retains an important role for MM cell survival. Knockdown of either K- or N-RAS strongly decreased the viability of MM cells that harbored the respective oncogenic isoform, whereas ablation of wild-type RAS isoforms had little or no effect. Silencing of oncogenic RAS did not affect the Akt pathway, again indicating lack of a direct link. Combined inhibition of RAS and Akt strongly enhanced MM cell death. These data suggest that oncogenic RAS and Akt may independently contribute to MM cell survival. Targeting of both pathways could provide an attractive therapeutic strategy for patients with oncogenic RAS and dysregulated Akt signaling.
authors.affiliation: Department of Internal Medicine II, Division of Hematology and Medical Oncology, and Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany. steinbrunn_t@medizin.uni-wuerzburg.de
authors.forename: Torsten
authors.initials: T
authors.lastname: Steinbrunn
authors.forename: Thorsten
authors.initials: T
authors.lastname: Stühmer
authors.forename: Stefan
authors.initials: S
authors.lastname: Gattenlöhner
authors.forename: Andreas
authors.initials: A
authors.lastname: Rosenwald
authors.forename: Anja
authors.initials: A
authors.lastname: Mottok
authors.forename: Christian
authors.initials: C
authors.lastname: Unzicker
authors.forename: Hermann
authors.initials: H
authors.lastname: Einsele
authors.forename: Manik
authors.initials: M
authors.lastname: Chatterjee
authors.forename: Ralf C
authors.initials: RC
authors.lastname: Bargou
mesh_terms: D001483:Base Sequence; D045744:Cell Line, Tumor; D002470:Cell Survival; D017931:DNA Primers / Q000235:genetics; D055785:Gene Knockdown Techniques; D011905:Genes, ras; D006801:Humans; D020935:MAP Kinase Signaling System; D009101:Multiple Myeloma / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D009154:Mutation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction
chemical_list: D017931:DNA Primers; D034741:RNA, Small Interfering; D051057:Proto-Oncogene Proteins c-akt