Cell-to-cell interaction of cytokine-dependent myeloblastic line constitutively expressing membrane-bound stem cell factor abrogates cytokine dependency partially through granulocyte-macrophage colony-stimulating factor production.
Stem cell factor (SCF) is a cytokine for hematopoietic progenitor cells and plays an important role in megakaryocyte proliferation. The UT-7 cell line was established from a patient with megakaryoblastic leukemia, and its growth and survival are strictly dependent on interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), erythropoietin (Epo), or IL-6. In this study, we showed that SCF also supported the growth of UT-7 in the absence of other cytokines and downregulated the cell surface c-kit receptors. Constitutive expression of SCF by introducing SCF expression vector made UT-7 grow factor-independently in liquid medium, but not in semisolid medium. This SCF-expressing factor-independent UT-7 (UT-7scf9) expressed the membrane bound form of SCF on their surface, but did not secrete detectable amounts of soluble SCF. UT-7scf9 formed aggregates as they grew in the absence of cytokines, and this aggregation was inhibited by adding soluble SCF into the medium. UT-7 cultured with SCF and UT-7scf9 cultured without cytokines expressed GM-CSF, and anti-GM-CSF neutralizing antibody partially inhibited their growth. These results suggest that SCF stimulated UT-7 proliferation partially through the autocrine-loop of GM-CSF, and UT-7scf9 expressed SCF mostly as a membrane-bound form, which transduces its growth signal through c-kit receptor as they aggregate by cell-to-cell interaction.
Sasaki
K
K
First Department of Internal Medicine, Kagawa Medical School, Japan.
Ikeda
K
K
Ogami
K
K
Takahara
J
J
Irino
S
S
D001483:Base Sequence; D002449:Cell Aggregation; D002450:Cell Communication; D002455:Cell Division / Q000187:drug effects; D003470:Culture Media / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics; D015536:Down-Regulation; D015973:Gene Expression Regulation, Leukemic; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis*; D016298:Hematopoietic Cell Growth Factors / Q000378:metabolism* / Q000494:pharmacology*; D006801:Humans; D007377:Interleukin-3 / Q000096:biosynthesis; D007947:Leukemia, Megakaryoblastic, Acute / Q000473:pathology*; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D016184:Receptors, Colony-Stimulating Factor / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D019089:Stem Cell Factor; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism
D003470:Culture Media; D018076:DNA, Complementary; D016298:Hematopoietic Cell Growth Factors; D007377:Interleukin-3; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D016184:Receptors, Colony-Stimulating Factor; D011993:Recombinant Fusion Proteins; D019089:Stem Cell Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases