In vitro-generated stem cell leukaemia showing altered cell cycle progression with distinct signalling of the tyrosine-phosphorylated rasGAP-associated p62(dok) protein.
In an attempt to gain more insight into the events of leukaemic transformation, a cell line overexpressing MHC class II (DR) was generated by transfecting an early CD34-negative haematopoietic progenitor stem cell line with the appropriate constructs. The stable transfection with genes for DR antigens leads to cellular transformation. The DR(+) transformed cell clones express a tyrosine-phosphorylated DR heterodimer and show a significantly different morphology. DR(+) clones present the morphology of an immature myeloid neoplasia expressing alpha-naphthyl-acetate-esterase (ANAE), but neither myeloperoxidase nor CD34. While D064 cells predominately grow adherent as fibroblast-like cells, the DR(+) clones display a decrease in adherent growth. Although both cell lines express similar amounts of the interleukin-6 (IL-6) signal transducer gp130, the DR-transfected cells still show activation of STAT factors by IL-6, whereas D064 cells do not. Although the transformed clones present acceleration of cell-cycle transition and growth, the G(0)/G(1) progression inhibitor p27(kip-1) is up-regulated, while the expression of proteins involved in the S/G(2) phase transition, such as cyclin B and cdc2 (p34), is suppressed. Instead cyclin D3, one of the G(0)/G(1) progression factors, is up-regulated, as well as tyrosine-phosphorylated p62(dok), suggesting dysregulation of cell cycle-controlling proteins. In addition, DR(+) leukaemia-like cells also overexpress Bcl-2, while bax expression is suppressed, compared with the wild-type (wt) parental haematopoietic stem cell line.
Huss
R
R
Institute of Pathology, University of Munich, Thalkirchner Str. 36, D-80337 Munich, Germany. Ralf.Huss@lrz.uni-muenchen.de
Weissinger
E M
EM
Lange
C
C
Gatsios
P
P
Eissner
G
G
Kolb
H J
HJ
Diebold
J
J
Heinrich
P C
PC
Graeve
L
L
D000208:Acute Disease; D017209:Apoptosis; D015152:Blotting, Northern; D015153:Blotting, Western; D002450:Cell Communication; D002453:Cell Cycle; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D006684:HLA-DR Antigens / Q000502:physiology; D006801:Humans; D020287:In Situ Nick-End Labeling; D015850:Interleukin-6 / Q000502:physiology; D007938:Leukemia / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D020703:ras GTPase-Activating Proteins / Q000502:physiology*
D006684:HLA-DR Antigens; D015850:Interleukin-6; D020703:ras GTPase-Activating Proteins