Molecular mechanism of AFP-specific liver tumor vaccines killing HepG2 hepatocellular carcinoma(HCC) cells in vitro

Abstract

Objective To prepare AFP-specific CD8+ T lymphocyte liver tumor vaccine, and investigate its anti-tumor activity in vitro and the related molecular mechanism. Methods We used AFP-specific dendritic cells (DC) which were activated by either AFP peptide (AFP542-550)-pulsed or lenti-AFP-engineered to activate AFP-specific CD8+ T lymphocyte in vitro, and investigated the anti-tumor activity of AFP-specific CD8+ T lymphocytes (AFP-CD8+ -CTL). The anti-human CD134 or anti-human CD28 monoclonal antibody was used to block or activate AFP-CD8+ -CTL and FasL signaling, and cytokines released such as IL-2, IFN-γ, perforin, granzyme B and FasL were detected to determine the direct role of perforin/granzyme B pathway in this anti-tumor effect. Results The results demonstrated that anti-human CD134 monoclonal antibody could block the activity of AFP-CD8+ -CTL, which could not efficiently kill HepG2 cells by decreasing the level of IL-2, IFN-γ, perforin and granzyme B significantly (P<0.05). When AFP-CD8+ -CTL was cocultured with anti-human CD28 monoclonal antibody, the AFP-specific T cells could efficiently kill HepG2 cells by significantly increasing the level of IL-2, IFN-γ, perforin and granzyme B (P<0.05). No obvious change was observed on FasL level. Conclusions The anti-human CD134 and anti-human CD28 monoclonal antibody could inhibit and activate AFP-CD8+ -CTL. The perforin/granzyme B pathway might play an important role in the anti-tumor activity of liver tumor vaccines. Key words: Hepatocellular carcinoma; Alpha-fetoprotein; Tumor vaccine; Molecular Mechanism