OBJECTIVETo explore the expression of epidermal growth factor receptor (EGFR) in hematopoietic cells and investigate its relationship to apoptosis in myelodysplastic syndrome (MDS) patients.

METHODMononuclear cells from 18 MDS patients were used to analyze the expression of EGFR and the apoptotic signals by immunocytochemical technique and TdT-mediated dUTP nick end labelling (TUNEL) fluorescein. Flow cytometry (FCM) sorted CD(34)(+) cells from 15 MDS cases and 6 normal donors were also analyzed for the EGFR expression and apoptotic signals. Nine normal marrow samples were taken as controls. EGFR expression and its relationship to apoptosis were analysed.

RESULTS(1) There was a higher EGFR expression rate (38.6 +/- 24.6)% in nucleated cells of MDS marrow than in normal marrow (18.1 +/- 14.0)% (P < 0.05). (2) Apoptosis occurred much more in EGFR negative cells (16.1%) than in EGFR positive cells (1.4%) (P < 0.01). EGFR expression showed negative correlation with apoptosis (r = -0.701; t(r) = 3.60; P < 0.01). (3) In CD(34)(+) cells, EGFR expression rate seemed higher in RAEB/RAEB-t/CMML than that in RA/RAS (20.6 +/- 27.9 vs 8.9 +/- 11.8%) subgroup (P > 0.05), while apoptosis was lower in RAEB/RAEB-t/CMML subgroup than in RA/RAS cases (18.2 +/- 12.5 vs 45.2 +/- 20.5%) (P < 0.05).

CONCLUSIONThere is overexpression of EGFR in MDS cases. And it seems that the overexpressed EGFR represent somewhat the malignant proliferation in MDS and suppress apoptosis through a unknown mechanism.

Adult ; Aged ; Apoptosis ; Bone Marrow Cells ; metabolism ; Female ; Flow Cytometry ; Humans ; In Situ Nick-End Labeling ; Male ; Middle Aged ; Myelodysplastic Syndromes ; metabolism ; pathology ; Receptor, Epidermal Growth Factor ; biosynthesis

The study was aimed to investigate the biological behavior of stromal cell-derived factor-1 (SDF-1) in migration, adhesion and apoptosis as well as the related signaling transduction pathways in different kinds of acute myeloid leukemia (AML) cell lines. The expression of surface molecules on AML (KG1a, ML1 and U937) cells were analyzed by flow cytometry. The cell adhesion was detected by MTT assay. The cell migration was checked by transwell assay. Bcl-xl was checked by immunoblotting after activation of phosphionositide-3 kinase (PI3K) in AML cells treated with SDF-1. The results indicated that the expressions of the surface molecules on AML (KG1a, ML1 and U937) cells were different. The list of the expression showed CD34 (KG1a = 95.6%, ML1 = 4.6%, U937 = 4.8%), CD45 (KG1a = 98.3%, U937 = 97.5%, ML1 = 17.8%), CXCR4 (ML1 = 85.4%, U937 = 43.6%, KG1a = 3.8%), ICAM (KG1a = 75.8%, U937 = 41.8% and ML1 = 46.3%). SDF-1 could not upregulate their expression, but could trigger the establishment of polarized morphology of the cells which expressed CXCR4 high. SDF-1 promoted ML1 and U937 cell adhesion to the stroma cells (HS5, HS27), stimulated PI3K in the cells. It was also confirmed that SDF-1 could increase the leukemic cell survival by stimulate this pathway. After addition of wortmaninn or PTX, the cell death increased. It is concluded that the SDF-1 increases the leukemic cell adhesion, migration and survival by stimulating the PI3K pathway. These functions can be depressed by the PI3K inhibitor and also the inhibitor of G protein as well.
Apoptosis ; drug effects ; Cell Adhesion ; drug effects ; Cell Movement ; drug effects ; Chemokine CXCL12 ; physiology ; Humans ; Leukemia, Myeloid, Acute ; pathology ; Phosphatidylinositol 3-Kinases ; metabolism ; Signal Transduction ; Tumor Cells, Cultured ; U937 Cells