TRAIL is involved in the tumoricidal activity of mouse natural killer cells stimulated by Newcastle disease virus in vitro.

Newcastle disease virus (NDV) is a potential antitumor agent, and its antitumor effect has been evaluated in preclinical tests. However, the mechanisms of NDV-based antitumor therapy are still not completely clear. In the present study we found that NDV-stimulation enhanced the killing ability of mouse spleen natural killer (NK) cells towards mouse hepatoma cell lines, and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) plays an important role in this tumoricidal activity. NDV stimulation induced up-regulation of TRAIL both at the mRNA and protein levels in NK cells. Blocking TRAIL by antibody (Ab) almost completely eliminated the killing effect of NK cells on hepatoma cell lines. Furthermore, neutralizing interferon (IFN)-γ by Ab could inhibit TRAIL expression and tumoricidal activity of NDV-stimulated NK cells. These results indicated a substantial role of TRAIL as an effector molecule in NDV-induced NK cells mediated tumoricidal activity. The NDV stimulation triggered TRAIL expression in mouse spleen NK cells could be mediated by IFN-γ induction.