Effects of dexamethasone on Flt3 receptor expression and proliferation induced by recombinant human Flt3 ligand in malignant hematopoietic cells.
OBJECTIVE
To investigate the effect of dexamethasone (DXM) on the expression of Flt3 receptor and the proliferation mediated by recombinant human Flt3 ligand (rhFL) in leukemia cells.


METHODS
Eighteen malignant hematopoietic cell lines and 10 leukemia blasts from leukemia patients were examined by flow cytometry for the expression of Flt3 receptor before and after incubation with DXM 0.1 micromol/L for 24 h. The effect of DXM on the proliferation of malignant hematopoietic cells was measured by MTT assay.


RESULTS
(1) Expression of the Flt3 receptor in malignant hematopoietic cell lines and leukemia blasts was widespread and extremely heterogeneous; (2) The presence of receptor on the surface of malignant hematopoietic cell didn't necessarily imply a significant ligand-induced response, at least in terms of proliferation. Conversely, some Flt3 receptor-negative malignant hematopoietic cells responded to rhFL; (3) DXM down-regulated the expression of Flt3 receptor and inhibited the proliferation induced by rhFL in some malignant hematopoietic cell lines and fresh leukemia cells.


CONCLUSIONS
DXM may down-regulate the expression of Flt3 receptor on the surface of malignant hematopoietic cells and inhibit the proliferation induced by rhFL. A combination of rhFL and DXM may serve to control hematopoietic defects in malignant hematopoietic diseases.
Xu
Z X
ZX
Department of Immunology, Medical Biotechnology Institute, School of Life Science, Soochow University, Suzhou 215007, China.
Xu
Y
Y
Zhu
J K
JK
Li
C X
CX
Li
Y
Y
Zhang
X G
XG
D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology*; D006410:Hematopoiesis / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000187:drug effects; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000473:pathology; D008565:Membrane Proteins / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000378:metabolism; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000096:biosynthesis*
D018931:Antineoplastic Agents, Hormonal; D008565:Membrane Proteins; D011994:Recombinant Proteins; C084881:flt3 ligand protein; D003907:Dexamethasone; D040281:Vascular Endothelial Growth Factor Receptor-1