ABSTRACT
BACKGROUND: Cancer development relies on a variety of mechanisms that facilitate tumor growth despite the presence of a functioning immune system, employing different mechanisms to escape immune rejection. Tumors may eliminate tumor-infiltrating lymphocytes and suppress anti-tumor immune responses, a process called "tumor counterattack," based on activation-induced cell death via the FAS/FAS-ligand system. To overcome this tumor-cell survival strategy, we examined the hypothesis that the sensitivity of FAS mediated apoptosis of Jurkat-T-cells can be suppressed by FLIP transfection of Jurkat-T-cells. MATERIALS AND METHODS: Jurkat-T-cells were transfected with the FLICE-inhibitory protein FLIP in order to bestow them with a resistance to FAS-receptor-mediated apoptosis. FLIP-transfected and non-transfected Jurkat-T-cells were grown in coincubation with SW620 cells and the rates of apoptosis measured via FACS-analysis of Annexin-V. RESULTS: First, the tumor-counterattack described in the literature was confirmed. About 20% of Jurkat-T-Cells underwent apoptosis in coculture with SW620 cells. After coincubation of SW620 cells with FLIP transfected Jurkat-T-cells the apoptotic rate was significant reduced at levels below 4%. CONCLUSION: Transfection of Jurkat-T-cells with FLIP reduces the sensitivity of Jurkat-T-cells to FAS-mediated apoptosis and may lead to an improved capability to antagonize the inherent tumor survival strategy of SW620 cells.
