Abstract
Background: CD137 is identified as a target for tumor immunotherapy. However, the role of CD137 in gastric cancer (GC), especially in inducing GC cell apoptosis has not been studied yet. Methods: Foxp3+ and CD8+ T cells in GCs were investigated by immunohistochemistry (IHC). CD137 expression in GCs was detected by flow cytometry, IHC and immunofluorescence (IF). Peripheral blood mononuclear cells (PBMCs) and CD8+ T cells isolated from peripheral blood were stimulated with a CD137 agonist in vitro. CD8+ T cells proliferation and p65 expression were explored by flow cytometry. p65 nuclear translocation was analyzed by IF. IL-10, TGF-β, IFN-γ, Perforin and Granzyme B were detected by real-time quantitative PCR (real-time PCR). PBMCs and primary GC cells were cocultured and stimulated with the CD137 agonist in vitro. Apoptosis of the primary GC cells was detected by flow cytometry. Results: Our data demonstrated that GC tumors show characteristics of an immunosuppressive microenvironment. CD137 was predominantly expressed in CD8+ T cells in GCs and had a positive correlation with tumor cell differentiation. CD137 agonist promoted CD8+ T cells proliferation and increased the secretion of IFN-γ, Perforin and Granzyme B, which induced primary GC cell apoptosis. Mechanistically, this study found that CD137 agonist could induce NF-κB nuclear translocation in CD8+ T cells. Conclusion: Our results demonstrate that CD137 agonist can induce primary GC cell apoptosis by enhancing CD8+ T cells via activating NF-κB signaling.
Real Time Detection of In Vitro Tumor Cell Apoptosis Induced by CD8+ T Cells to Study Immune Suppressive Functions of Tumor-infiltrating Myeloid Cells