Stem cell factor-induced downregulation of c-kit in human lung mast cells and HMC-1 mast cells.
Recent data suggest that local overexpression of the tissue-hormone c-kit ligand (stem cell factor [SCF]) is associated with accumulation of mast cells (MCs) and a decrease in expression of c-kit in the accumulated MCs [28]. In the present study, the effects of recombinant human (rh) SCF on expression of c-kit mRNA and c-kit protein in isolated human MCs and a human mast cell line, HMC-1, were analyzed. Incubation of isolated lung MC with rhSCF (100 ng/mL) for 120 minutes resulted in decreased expression of c-kit mRNA (optical density [OD], control: 100% vs. rhSCF: 37%). Almost identical results were obtained with HMC-1 cells (OD, control: 100% vs. rhSCF: 40 to 45%). As assessed by flow cytometry and monoclonal antibodies (mAbs) to c-kit, the SCF-induced decrease of c-kit mRNA in HMC-1 was associated with a substantial decrease in surface expression of c-kit (MFI, control: 100 +/- 21%, vs. MFI in cells incubated with rhSCF [100 ng/mL at 37 degrees C for 12 hours]: 8 +/- 2%, vs. MFI in cells incubated with rhSCF, 100 ng/mL, at 4 degrees C: 34 +/- 3%). The effects of rhSCF on c-kit expression in HMC-1 cells were dose- and time-dependent with maximum effects observed with 10-100 ng/mL of rhSCF after 4 to 12 hours. The SCF-dependent loss of c-kit was also accompanied by a decreased chemotactic response to rhSCF (control: 100%; rhSCF: 71 +/- 2%). This study shows that exposure of human lung MC and HMC-1 cells to recombinant SCF results in downregulation of c-kit mRNA and surface c-kit expression. These data may explain the partial loss of c-kit on MCs in areas of SCF overexpression.
Department of Internal Medicine I, University of Vienna, Austria.
M
M
Baghestanian
H
H
Agis
D
D
Bevec
H C
HC
Bankl
R
R
Hofbauer
H G
HG
Kress
J H
JH
Butterfield
M R
MR
Müller
L K
LK
Ashman
W
W
Füreder
M
M
Willheim
K
K
Lechner
P
P
Valent
D015152:Blotting, Northern; D002460:Cell Line; D002633:Chemotaxis / Q000187:drug effects; D015536:Down-Regulation; D006801:Humans; D007124:Immunoenzyme Techniques; D008168:Lung / Q000166:cytology*; D008407:Mast Cells / Q000737:chemistry / Q000166:cytology*; D008565:Membrane Proteins / Q000096:biosynthesis; D015345:Oligonucleotide Probes / Q000032:analysis; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000494:pharmacology; D019089:Stem Cell Factor / Q000494:pharmacology*
D008565:Membrane Proteins; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D011994:Recombinant Proteins; D019089:Stem Cell Factor; D019009:Proto-Oncogene Proteins c-kit