Abstract
NKG2D ligand express in raft area on the cellular membrane. Tumor cells express much NKG2D ligand by stress, such as radiation. But tumor cells do not exclude in the immune system, because of secretion of NKG2D ligand by mechanism of tumor cells. This mechanism is not clear. In this study, we elucidated the mechanism of X-ray induced-expression and secretion of NKG2D ligand on the tumor cell surface.
NKG2D ligand was retained on the membrane raft and the vicinity of raft after irradiation for 1hr, this retention was suppressed by SMase inhibitor. When MMP14 in the exosome observed after irradiation, active MMP14 was observed in the exosome, and MMP14 was not observed in the exosome by SMase inhibitor. These results indicate that degradation of NKG2D ligand was inhibited by the secretion of MMP14 that mediated SMase activation by irradiation.
