Direct tumor lysis by NK cells uses a Ras-independent mitogen-activated protein kinase signal pathway.
Destruction of tumor cells is a key function of lymphocytes, but the molecular processes driving it are unclear. Analysis of signal molecules indicated that mitogen-activated protein kinase (MAPK)/extracellular regulated kinase 2 critically controlled lytic function in human NK cells. We now have evidence to indicate that target ligation triggers a Ras-independent MAPK pathway that is required for lysis of the ligated tumor cell. Target engagement caused NK cells to rapidly activate MAPK within 5 min, and PD098059 effectively blocked both MAPK activation and tumoricidal function in NK cells. Target engagement also rapidly activated Ras, detected as active Ras-GTP bound to GST-Raf-RBD, a GST fusion protein linked to the Raf protein fragment containing the Ras-GTP binding domain. However, Ras inactivation by pharmacological disruption with the farnesyl transferase inhibitor, FTI-277, had no adverse effect on the ability of NK cells to lyse tumor cells or to express MAPK activation upon target conjugation. Notably, MAPK inactivation with PD098059, but not Ras inactivation with FTI-277, could interfere with perforin and granzyme B polarization within NK cells toward the contacted target cell. Using vaccinia delivery of N17 Ras into NK cells, we demonstrated that IL-2 activated a Ras-dependent MAPK pathway, while target ligation used a Ras-independent MAPK pathway to trigger lysis in NK cells.
Wei
S
S
H. Lee Moffitt Cancer Center, Department of Biochemistry and Molecular Biology, University of South Florida College of Medicine, Tampa 33612, USA.
Gilvary
D L
DL
Corliss
B C
BC
Sebti
S
S
Sun
J
J
Straus
D B
DB
Leibson
P J
PJ
Trapani
J A
JA
Hamilton
A D
AD
Weber
M J
MJ
Djeu
J Y
JY
D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors; D002460:Cell Line; D016764:Cell Polarity / Q000276:immunology; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053804:Granzymes; D006801:Humans; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D007694:Killer Cells, Natural / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism; D008024:Ligands; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D008715:Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D017368:Protein Prenylation / Q000187:drug effects / Q000276:immunology; D012697:Serine Endopeptidases / Q000378:metabolism; D014407:Tumor Cells, Cultured; D018631:ras Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*
D004791:Enzyme Inhibitors; C096856:FTI 277; D007376:Interleukin-2; D008024:Ligands; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D008715:Methionine; D019883:Alkyl and Aryl Transferases; C064911:p21(ras) farnesyl-protein transferase; D020928:Mitogen-Activated Protein Kinases; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases; D018631:ras Proteins