[The expression and effects of isoforms of macrophage colony stimulating factor in human leukemic cell lines].
OBJECTIVE
To explore the expression and effects of isoforms of macrophage colony-stimulating factor (M-CSF) in human leukemic cell lines.


METHODS
Three normal human peripheral blood mononuclear cells (PBMCs) and 4 human myelomonocytic leukemic cell lines including J6-1, J6-2, K562 and HL-60 were studied using ABC immunoperoxidase assay, indirect immunofluorescence staining, flow cytometry, Western blot and reverse enzyme-linked DNA-protein interaction assay (reverse ELDIA).


RESULTS
M-CSF was noticed to be localized in the cytoplasm, nucleus and at the cell membrane in 4 human leukemic cell lines; expression of M-CSF was not detected in normal human PBMCs without PHA stimulation. Human PBMCs stimulated by PHA expressed a low level of M-CSF. Frequencies of membrane bound M-CSF expression in J6-1, J6-2, K562 and HL-60 were 71.6%, 69.7%, 42.7% and 57.4% respectively. Frequencies of cytoplasm and nucleus associated M-CSF were 65.7%, 45.4%, 36.5% and 72.5% respectively. The cytosolic bound M-CSF was expressed in J6-1 cell as four isoforms with a molecular weight of 14,000, 16,000, 20,000 and 44,000. While nucleus associated M-CSF expressed as two isoforms with a molecular weight of 16,000 and 20,000. Anti-M-CSF monoclonal antibody could dramatically inhibit proliferation of leukemic cells and its inhibitory effect was related to the levels of membrane bound M-CSF expression in leukemic cells. Reverse ELDIA showed that M-CSF could bind with DNA in vitro.


CONCLUSIONS
Expression of M-CSF isoforms is heterogeneous and polymorphous in leukemic cells. Membrane bound M-CSF is crucial for the proliferation of leukemic cells, which might be a DNA-bound protein and could be involved in the transformation and tumorigenesis of hematopoietic cells.
Tang
S
S
State Key Laboratory of Experimental Hematology, Institute of Hematology, Peking Union Medical College and Chinese Academy of Medical Sciences, Tianjin 300020, China.
Du
X
X
Chen
G
G
Rao
Q
Q
Geng
Y
Y
Wu
K
K
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000737:chemistry; D002467:Cell Nucleus / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D018922:HL-60 Cells; D006801:Humans; D020014:K562 Cells; D015479:Leukemia, Myelomonocytic, Acute / Q000378:metabolism* / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000166:cytology; D016173:Macrophage Colony-Stimulating Factor / Q000032:analysis* / Q000276:immunology; D020033:Protein Isoforms / Q000032:analysis
D000911:Antibodies, Monoclonal; D020033:Protein Isoforms; D016173:Macrophage Colony-Stimulating Factor