Role of signal transducer and activator of transcription 5 in nucleophosmin/ anaplastic lymphoma kinase-mediated malignant transformation of lymphoid cells.
The NPM/ALK fusion gene, formed by the t(2;5) translocation in anaplastic large-cell lymphoma, encodes a M(r) 75,000 hybrid protein that containsthe amino-terminal portion of the nucleolar phosphoprotein nucleophosmin(NPM) joined to the entire cytoplasmic portion of the receptor tyrosine kinase anaplastic lymphoma kinase (ALK). NPM/ALK encodes a constitutively activated tyrosine kinase that belongs to the family of tyrosine kinases activated by chromosomal translocation. Our studies show that NPM/ALK, similar to other members of this family, activates signal transducer and activator of transcription 5 (STAT5) and that this activation is essential for lymphomagenesis. NPM/ALK-mediated activation of STAT5 was demonstrated by detection of: (a) constitutive tyrosine phosphorylation and enhanced DNA binding ability of STAT5 in NPM/ALK-transformed cells; and (b) NPM/ALK-dependent stimulation of STAT5-mediated transactivation of the beta-casein promoter. Retroviral infection of NPM/ALK+ cells with a dominant-negative STAT5B mutant (STAT5-DNM) inhibited the antiapoptotic activity of NPM/ALK in growth factor and serum-free medium. In addition, STAT5-DNM inhibited proliferation and diminished the clonogenic properties of NPM/ALK-positive cells. Finally, SCID mice injected with NPM/ALK+ cells infected with a virus carrying STAT5-DNM survived significantly longer than mice inoculated with NPM/ALK+ cells infected with the empty virus. Necropsy identified a widespread ALK+ lymphoma in lymph nodes and liver of the affected animals. Together, our data indicate that NPM/ALK-induced activation of STAT5 may play an important role in NPM/ALK-mediated lymphomagenesis.
Nieborowska-Skorska
M
M
Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, USA.
Slupianek
A
A
Xue
L
L
Zhang
Q
Q
Raghunath
P N
PN
Hoser
G
G
Wasik
M A
MA
Morris
S W
SW
Skorski
T
T
D000818:Animals; D002471:Cell Transformation, Neoplastic; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D005260:Female; D006133:Growth Substances / Q000502:physiology; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D008223:Lymphoma / Q000235:genetics / Q000473:pathology*; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D008894:Milk Proteins; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000502:physiology*; D050799:STAT5 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism / Q000502:physiology*; D014162:Transfection
D004268:DNA-Binding Proteins; D006133:Growth Substances; D008894:Milk Proteins; D050799:STAT5 Transcription Factor; C494095:STAT5B protein, human; C494096:Stat5b protein, mouse; D015534:Trans-Activators; C107023:p80(NPM-ALK) protein; D011505:Protein-Tyrosine Kinases