title: FK506 and cyclosporin A inhibit stem cell factor-dependent cell proliferation/survival, while inducing upregulation of c-kit expression in cells of the mast cell line MC/9.
abstract: Murine mast cell proliferation and maturation are regulated by two distinct cytokines, interleukin-3 (IL-3) and the c-kit ligand, stem cell factor (SCF). In this study using cells of the mouse mast cell line, MC/9, the effects of two immunosuppressants, FK506 and cyclosporin A (CsA), were investigated. Withdrawal of IL-3 from the culture medium resulted in loss of viability of MC/9 cells. The addition of SCF in the absence of IL-3 maintained MC/9 cell survival but no cell proliferation was detected. The combined addition of IL-3 and SCF to the culture medium resulted in a more marked MC/9 cell proliferation than the addition of IL-3 alone. FK506 and CsA inhibited the SCF-dependent, but not the IL-3 dependent, stimulatory effects on MC/9 cell proliferation/survival. Apoptotic changes were analyzed using fluorescent staining with acridine orange and DNA electrophoresis. FK506 and CsA inhibited the SCF-dependent rescue effect from apoptosis. Flow cytometry showed that FK506 and CsA did not affect IL-3 receptor expression. However, immunoblot and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses indicated that c-kit protein and c-kit mRNA transcripts were increased following the FK506 and CsA treatments in the presence of IL-3. In addition, MC/9 cells pretreated with FK506 or CsA showed an increased adhesiveness to NIH/3T3 cells that express membrane-bound SCF. Neither FK506 nor CsA affected c-kit tyrosine phosphorylation or MAP kinase nuclear translocation of MC/9 cells following SCF stimulation. These results indicate that FK506 and CsA, while inducing c-kit of MC/9 cells, selectively inhibit the SCF-dependent stimulatory effects on MC/9 cell proliferation/survival by a mechanism independent of, or at point(s) distal to, the c-kit-MAP kinase pathway.
authors.affiliation: Department of Dermatology, Asahikawa Medical College, Hokkaido, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Ito
authors.forename: N
authors.initials: N
authors.lastname: Toyota
authors.forename: H
authors.initials: H
authors.lastname: Sakai
authors.forename: H
authors.initials: H
authors.lastname: Takahashi
authors.forename: H
authors.initials: H
authors.lastname: Iizuka
mesh_terms: D016475:3T3 Cells / Q000187:drug effects; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D016572:Cyclosporine / Q000494:pharmacology*; D007377:Interleukin-3 / Q000494:pharmacology; D008407:Mast Cells / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D010766:Phosphorylation; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D019089:Stem Cell Factor / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D016559:Tacrolimus / Q000494:pharmacology*; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D007377:Interleukin-3; D019089:Stem Cell Factor; D016572:Cyclosporine; D019009:Proto-Oncogene Proteins c-kit; D016559:Tacrolimus