Mutant N-ras preferentially drives human CD34+ hematopoietic progenitor cells into myeloid differentiation and proliferation both in vitro and in the NOD/SCID mouse.
OBJECTIVE
Ras oncogene mutations are the most frequently observed genetic abnormality (20-40% of patients) in acute myeloid leukemia (AML), and in the preleukemic conditions myelodysplastic syndrome (MDS) and myeloproliferative disorder (MPD). We have previously shown that mutant N-ras (N-rasm) can induce myeloproliferative disorders and apoptosis in a murine reconstitution system. In the present study we investigated the effect of N-rasm in human primary hematopoietic progenitor cells (HPC).


METHODS
Cord blood CD34+ hematopoietic progenitor cells (HPC) were transduced with retroviral vectors containing green fluorescence protein (GFP) alone, or in combination with N-rasm. Cells were then cultured in vitro with a cytokine supplement or cocultured with murine stroma MS-5 cells. The in vivo behavior of transduced cells was examined in the NOD/SCID mouse model.


RESULTS
N-rasm-transduced cells exhibited greater proliferative capacity; a higher frequency of granulocyte-macrophage colony-forming unit (CFU-GM); and an increase in myelomonocytic lineage cells with a concomitant decrease in lymphoid and erythroid cells. Analysis of transduced HPC in NOD/SCID mice revealed higher bone marrow engraftment by N-rasm HPC and increased numbers of myeloid lineage cells.


CONCLUSIONS
The results demonstrate that N-rasm in HPC induces myeloproliferation both in vitro and in the NOD/SCID mouse model as a primary event that does not appear to be dependent on cooperating transforming events.
Shen
Sylvie W
SW
Children's Cancer Institute Australia for Medical Research, Randwick, NSW, Australia.
Dolnikov
Alla
A
Passioura
Toby
T
Millington
Michelle
M
Wotherspoon
Simon
S
Rice
Alison
A
MacKenzie
Karen L
KL
Symonds
Geoff
G
D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis*; D002454:Cell Differentiation; D002455:Cell Division; D019070:Cell Lineage; D011905:Genes, ras / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D022423:Myeloid Cells / Q000166:cytology*
D018952:Antigens, CD34