Coexpression of stem cell factor and its receptor c-Kit in human malignant glioma cell lines.
Stem cell factor (SCF), a hematopoietic growth factor, is the ligand of the tyrosine kinase receptor encoded by the c-kit proto-oncogene. Beside the important role of this receptor-ligand complex in hematopoiesis, gametogenesis and melanogenesis, SCF and its receptor have been shown to be expressed in the brain. We have studied the expression of SCF and c-kit in 20 human malignant glioma cell lines at the mRNA as well as at the protein level. In addition, recombinant human (rh) SCF was tested in [3H]thymidine uptake assays for a mitogenic effect on these cells. SCF and c-Kit proteins were detected in the cytoplasm of glioma cells by alkaline phosphatase-monoclonal anti-alkaline phosphatase immunostaining and Western blot analysis. However, neither SCF nor c-Kit were seen on the cell surface by flow cytometry. Furthermore, none of the proliferation assays showed a mitogenic effect for exogenously added rhSCF. Blocking studies using an anti-SCF antibody failed to demonstrate modulating effects on the growth of selected cell lines. These results suggest that SCF and c-Kit may mediate non-proliferative signals or may employ intracellular mechanisms for autocrine growth regulation of glioma cells.
Stanulla
M
M
Department of Pediatric Hematology and Oncology, Medical School Hannover, Germany.
Welte
K
K
Hadam
M R
MR
Pietsch
T
T
D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D005434:Flow Cytometry; D015870:Gene Expression / Q000235:genetics*; D005910:Glioma / Q000235:genetics* / Q000378:metabolism; D016298:Hematopoietic Cell Growth Factors / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D016133:Polymerase Chain Reaction; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D016184:Receptors, Colony-Stimulating Factor / Q000235:genetics* / Q000378:metabolism; D019089:Stem Cell Factor
D015815:Cell Adhesion Molecules; D016298:Hematopoietic Cell Growth Factors; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D016184:Receptors, Colony-Stimulating Factor; D019089:Stem Cell Factor; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases