신세포암 세포주에서 Interferon-gamma (IFN-γ)에 의한 Fas-매개성 세포사의 유도

Abstract

Purpose: Interferon-gamma (IFN-g) is a cytokine involved in cellular immune responses and has antiproliferative and cytotoxic effects on tumor cells in vitro. IFN-g is also capable of increasing the expression of MHC class I and class II molecules and tumor markers thereby enhancing the immune responses against the tumor cells. It has been reported in a number of studies that several cytokines including interleukin-2, IFN-a, IFN-g, and tumor necrosis factor-alpha, induce Fas antigen expression on tumor cell surfaces and make the tumor cells sensitive to Fas/Fas ligand (Fas/FasL)-mediated apoptosis. In the purpose of determining the effect of IFN-g on the Fas/FasL-Mediated apoptotic pathway in Renca cell line, inducibility of Fas antigen and anti-Fas Ab-mediated apoptosis were investigated. Materials and Methods: Fas mRNA transcript and Fas antigen expression were demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry after IFN-g treatment on Renca. In order to induce cell death in the IFN-g-pretreated cells, Jo2, a cytotoxic anti-Fas Ab was used. The apoptotic characteristics of the Jo2-Induced Renca cell death were demonstrated by DNA fragmentation assay and FACS analysis. Results: Renca cells treated for 24 hours with 300U/ml of IFN-g, showed high-level expression of Fas mRNA and protein in RT-PCR and immunocytochemical staining. Jo2 was able to induce cell death after pretreatment of Renca with 150U/ml of IFN-g for 24 hours. Assays for DNA fragmentation revealed apoptosis-associated nucleosomal ladders in IFN-g and Jo2-treated Renca. Jo2-induced apoptosis was also confirmed by increased subdiploid DNA contents in flow cytometric analysis. Conclusions: These results suggest that IFN-g, by enhancing surface Fas expression, sensitizes Renca tumor cell line to Fas/FasL-mediated apoptosis. Key word : IFN-g, Apoptosis, Fas antigen