The protein tyrosine phosphatase CD45 is required for interleukin 6 signaling in U266 myeloma cells.
The objective of this study was to examine whether CD45 mediates interleukin 6 (IL-6) signaling in human multiple myeloma (MM) cells. We chose U266 MM cells as a study model and isolated cells into CD45+ and CD45- subpopulations. CD45+ and CD45- U266 cells were cocultured with bone marrow stromal cells (BMSCs). IL-6-induced proliferation in CD45+ U266 cells was inhibited by vanadate, a potent protein tyrosine phosphatase inhibitor. However, IL-6-independent CD45- U266 cell growth was not affected by vanadate. CD45+ U266 cells, but not CD45- U266 cells, have the capability of cell adhesion concomitant with actin filament polymerization at the adherent cells. Adhesion of CD45+ U266 cells to BMSCs was impaired by vanadate. We clarified the signaling differences between CD45+ and CD45- U266 cells in response to IL-6. In CD45+ U266 cells, IL-6 increased tyrosine phosphorylation of gp130 and STAT3 and stimulated the level of Mcl-1 protein expression. An association between CD45 and the Src-family protein tyrosine kinase, Lyn, was maintained in the presence of IL-6; the formation of the CD45/Lyn complex was impaired by vanadate. Additionally, IL-6-induced Lyn kinase activity in CD45+ U266 cells was increased by the cross-linking of CD45, and this increase was due to the dephosphorylation of Tyr507 at Lyn. In conclusion, IL-6-dependent MM cells require CD45 to initiate IL-6 signaling and to maintain Lyn kinase activity, both of which are essential for cell proliferation and cell adhesion.
Zhou
Qun
Q
Blood and Marrow Transplant and Hematologic Malignancy Program, Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, West Virginia 26506, USA.
Yao
Yuan
Y
Ericson
Solveig G
SG
D000199:Actins / Q000378:metabolism; D015703:Antigens, CD / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D002469:Cell Separation; D018920:Coculture Techniques; D050822:Cytokine Receptor gp130; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000502:physiology*; D017493:Leukocyte Common Antigens / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D009101:Multiple Myeloma / Q000473:pathology*; D009363:Neoplasm Proteins / Q000502:physiology*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D050796:STAT3 Transcription Factor; D015398:Signal Transduction / Q000502:physiology*; D017154:Stromal Cells / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D014638:Vanadates / Q000494:pharmacology; D019061:src-Family Kinases / Q000737:chemistry / Q000378:metabolism*
D000199:Actins; D015703:Antigens, CD; D004268:DNA-Binding Proteins; C494199:IL6ST protein, human; D015850:Interleukin-6; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D015534:Trans-Activators; D050822:Cytokine Receptor gp130; D019000:Phosphotyrosine; D014638:Vanadates; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D017493:Leukocyte Common Antigens