title: Multiple point mutation of N-ras and K-ras oncogenes in myelodysplastic syndrome and acute myelogenous leukemia.
abstract: We analyzed activating mutations of N-ras and K-ras by the polymerase chain reaction and oligonucleotide hybridization in hematological disorders. Activating mutations of these codons were detected in 4 of 20 cases of myelodysplastic syndrome (MDS) and 15 of 77 cases of acute myelogenous leukemia (AML). Our of 19 cases of MDS and AML who carried active mutations, 7 cases were found to have two or more distinct mutations in activating codons of N-ras and K-ras. Ras mutation was found preferentially in progressive disease such as refractory anemia with excess of blasts (RAEB) of RAEB in transformation (RAEB-t). A relatively high incidence of ras mutation was found in M5 AML (40%). No ras mutations were found in other hematological disorders, such as acute lymphoblastic leukemia and chronic myelogenous-leukemia. The most frequent amino acid substitution was that of an aspartate for glycine at codon 12 of N-ras resulting from G to A mutation (11/35). The survival of AML patients who carried ras mutations showed no significant differences from those without ras mutations calculated by Kaplan-Meier. Seven cases of MDS and 7 cases of AML patients could be investigated at various points during their clinical course. Among these 14 cases, we found 2 interesting cases of MDS. The first case lost multiple clones carrying ras mutations during disease progression, the second case acquired mutation of the ras gene during disease progression. These results suggested that multiple point mutations of ras genes may not be initiating events but may contribute to a clonal evolution of MDS and AML.
authors.affiliation: Department of Medicine, Hyogo Medical Center for Adults, Akashi, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Nakagawa
authors.forename: S
authors.initials: S
authors.lastname: Saitoh
authors.forename: S
authors.initials: S
authors.lastname: Imoto
authors.forename: M
authors.initials: M
authors.lastname: Itoh
authors.forename: M
authors.initials: M
authors.lastname: Tsutsumi
authors.forename: K
authors.initials: K
authors.lastname: Hikiji
authors.forename: H
authors.initials: H
authors.lastname: Nakamura
authors.forename: S
authors.initials: S
authors.lastname: Matozaki
authors.forename: R
authors.initials: R
authors.lastname: Ogawa
authors.forename: Y
authors.initials: Y
authors.lastname: Nakao
mesh_terms: D000328:Adult; D000368:Aged; D001483:Base Sequence; D004252:DNA Mutational Analysis; D005260:Female; D011905:Genes, ras; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D009190:Myelodysplastic Syndromes / Q000235:genetics*; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D011379:Prognosis; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics; D016019:Survival Analysis
chemical_list: D009838:Oligodeoxyribonucleotides; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)