Abstract
Natural killer (NK) cells rely on surface receptors to distinguish healthy cells from cancer cells. We designed a receptor termed NKG2D-DAP10-CD3ζ that is composed of the NK cell activating molecule NKG2D plus 2 key signaling molecules, DAP10 and CD3ζ, and evaluated its capacity to promote cancer cell killing. Retroviral transduction of NKG2D-DAP10-CD3ζ markedly increased NKG2D surface expression in NK cells, which became consistently more cytotoxic than mock-transduced cells against leukemia and solid tumor cell lines. In contrast, there was no increase in cytotoxicity against nontransformed blood and mesenchymal cells. NKG2D blockade abrogated gains in cytotoxicity to cancer cells. Receptor stimulation triggered signal transduction, secretion of IFN-γ, GM-CSF, IL-13, MIP-1α, MIP-1β, CCL5, and TNF-α, and massive release of cytotoxic granules, which persisted after 48 hours of continuous stimulation. NKG2D-DAP10-CD3ζ-expressing NK cells had considerable antitumor activity in a mouse model of osteosarcoma, whereas activated NK cells were ineffective. Thus, the cytotoxic potential of NK cells against a wide spectrum of tumor subtypes could be markedly enhanced by expression of NKG2D-DAP10-CD3ζ receptors. The development of an electroporation method that permits rapid expression of the receptor in a large number of human NK cells facilitates clinical translation of this NK-based strategy for a generalized cellular therapy that may be useful to treat a wide range of cancers.
Highlights
Natural killer (NK) cells can recognize tumor cells as targets, a function that suggests possibilities for NK cell therapy of cancer [1]
We first determined whether retroviral transduction of the construct resulted in gains of NK Group 2 member D (NKG2D) expression as compared with cells transduced with an murine stem cell virus (MSCV) vector containing only green fluorescent protein (GFP)
The NKG2D activating receptor is central to the capacity of NK cells to sense cellular stress and lyse virally infected and tumor cells [1, 4, 6, 7, 9,10,11,12,13]
Summary
Natural killer (NK) cells can recognize tumor cells as targets, a function that suggests possibilities for NK cell therapy of cancer [1]. Inhibitory signals result from the interaction between NK inhibitory receptors and HLA molecules on potential target cells, whereas engagement of activating receptors by ligands expressed predominantly by virally infected and tumor cells provoke signals that cause target cell killing [1]. A key receptor for NK cell activation is NK Group 2 member D (NKG2D), a type II transmembrane-anchored C-type lectinlike protein expressed in all NK cells and in some T-cell subsets [2,3,4]. Authors' Affiliations: 1Department of Pediatrics, 2Department of Surgery, National University of Singapore; and 3Singapore Immunology Network, AÃSTAR, Singapore. Chang: Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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