Two transforming C-RAF germ-line mutations identified in patients with therapy-related acute myeloid leukemia.
Mutations leading to activation of the RAF-mitogen-activated protein kinase/extracellular signal-regulated (ERK) kinase (MEK)-ERK pathway are key events in the pathogenesis of human malignancies. In a screen of 82 acute myeloid leukemia (AML) samples, 45 (55%) showed activated ERK and thus were further analyzed for mutations in B-RAF and C-RAF. Two C-RAF germ-line mutations, S427G and I448V, were identified in patients with therapy-related AML in the absence of alterations in RAS and FLT3. Both exchanges were located within the kinase domain of C-RAF. In vitro and in vivo kinase assays revealed significantly increased activity for (S427G)C-RAF but not for (I448V)C-RAF. The involvement of the S427G C-RAF mutation in constitutive activation of ERK was further confirmed through demonstration of activating phosphorylations on C-RAF, MEK, and ERK in neoplastic cells, but not in nonneoplastic cells. Transformation and survival assays showed oncogenic and antiapoptotic properties for both mutations. Screening healthy individuals revealed a <1/400 frequency of these mutations and, in the case of I448V, inheritance was observed over three generations with another mutation carrier suffering from cancer. Taken together, these data are the first to relate C-RAF mutations to human malignancies. As both mutations are of germ-line origin, they might constitute a novel tumor-predisposing factor.
Division of Hematology, Medical University of Graz, Auenbruggerplatz 38, A-8036 Graz, Austria.
Armin
A
Zebisch
Philipp B
PB
Staber
Ali
A
Delavar
Claudia
C
Bodner
Karin
K
Hiden
Katja
K
Fischereder
Manickam
M
Janakiraman
Werner
W
Linkesch
Holger W
HW
Auner
Werner
W
Emberger
Christian
C
Windpassinger
Michael G
MG
Schimek
Gerald
G
Hoefler
Jakob
J
Troppmair
Heinz
H
Sill
D000208:Acute Disease; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001483:Base Sequence; D019556:COS Cells; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D002522:Chlorocebus aethiops; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015973:Gene Expression Regulation, Leukemic / Q000235:genetics; D011905:Genes, ras; D018095:Germ-Line Mutation; D018922:HL-60 Cells; D006801:Humans; D007951:Leukemia, Myeloid / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D020935:MAP Kinase Signaling System; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D016609:Neoplasms, Second Primary / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D010375:Pedigree; D010766:Phosphorylation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics*; D016415:Sequence Alignment; D051941:fms-Like Tyrosine Kinase 3 / Q000235:genetics
C497970:FLT3 protein, human; D051941:fms-Like Tyrosine Kinase 3; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases