title: Synergistic cytotoxic effects in myeloid leukemia cells upon cotreatment with farnesyltransferase and geranylgeranyl transferase-I inhibitors.
abstract: As deregulation of RAS signaling is important in the pathogenesis of myeloid leukemias, molecular targeting of RAS signaling may be a promising therapeutic strategy. Farnesyl transferase inhibitors (FTIs) are the most promising class of these new cancer therapeutics. Several FTIs have entered phase II clinical trials in acute myeloid leukemia (AML). Since geranylgeranylation of K-RAS and N-RAS in the presence of FTIs may represent an important mechanism of FTI resistance, 6 geranylgeranyl transferase-I inhibitors (GGTIs) were screened alone and in combination with FTI for growth inhibition of myeloid leukemia cells. Significant growth inhibition (>70%) in myeloid cell lines was observed for GGTI-286 (9/19), GGTI-298 (14/19), GGTI-2147 (16/19) and FTI L-744,832 (17/17). GGTI treatment of NB-4 cells resulted in an accumulation of cells in G(0)/G(1), whereas FTI L-744,832 primarily caused an increase in G(2)/M. FTI and GGTIs both induced apoptosis. In all cases, FTI/GGTI cotreatment led to synergistic cytotoxic effects in both myeloid cell lines (5/5) and primary AML cells (6/6). This synergy coincided with increased apoptosis. FTI/GGTI cotreatment caused an accumulation of unprocessed N-RAS and inactive N-RAS-RAF complexes. Our results suggest that alternative geranylgeranylation of N-RAS may represent an important mechanism of resistance to FTI monotherapy in myeloid leukemia cells.
authors.affiliation: Department of Hematology and Oncology, Hannover Medical School, Hannover, Germany.
authors.forename: M A
authors.initials: MA
authors.lastname: Morgan
authors.forename: J
authors.initials: J
authors.lastname: Wegner
authors.forename: E
authors.initials: E
authors.lastname: Aydilek
authors.forename: A
authors.initials: A
authors.lastname: Ganser
authors.forename: C W M
authors.initials: CW
authors.lastname: Reuter
mesh_terms: D000328:Adult; D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051231:Farnesyltranstransferase; D005434:Flow Cytometry; D006801:Humans; D007399:Interphase / Q000187:drug effects; D007951:Leukemia, Myeloid / Q000473:pathology*; D014407:Tumor Cells, Cultured; D018631:ras Proteins / Q000187:drug effects / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D019883:Alkyl and Aryl Transferases; C083291:geranylgeranyltransferase type-I; D051231:Farnesyltranstransferase; D018631:ras Proteins