Upregulation of Reactive Oxygen Species and Resistance to Fas-mediated Apoptosis in Cervical Cancer Cell Lines Transfected with the IL-18 Receptor / 대한진단검사의학회지

ABSTRACT

BACKGROUND: The fas (CD95/Apo-1)/Fas ligand (FasL) system is reported to be involved in the suppression and stimulation of immune responses, and the reactive oxygen species (ROS) play a key role in the mechanism for resisting Fas-induced apoptosis of tumor cells. In this work, we investigated the effect of endogenous interleukin (IL)-18 on the regulation of immune related factors such as Fas/Fas ligand and intercellular adhesion molecules (ICAM), and of the ROS level in IL-18 receptor (IL-18R) transfected C-33A cells. METHODS: The cervical cancer cell line C-33A was transfected with IL-18R (C-33A/IL-18R). For the detection of pro-inflammatory cytokines in C-33A/IL-18R, reverse-transcriptase (RT) polymerase chain reaction (PCR), in situ enzyme-linked immunosorbent assay (ELISA), Western blot, and Northern blot analyses were performed. The level of p53 was determined by Western blot. Intracellular ROS, ICAM-1, FasL, and apoptosis in C-33A/IL-18R were measured by flow cytometry. RESULTS: In situ ELISA and RT-PCR showed that, among pro-inflammatory cytokines, IL-18 was induced in C-33A/IL-18R whereas there appeared no induction of the IL-1alpha, IL-1beta, tumor necrosis factor (TNF)-alpha, and IL-6. IL-18R transfection showed a slight enhancement of the Fas via upregulation of intracellular ROS and IL-18 in C-33A cells whereas there was no effect on the expression of p53, ICAM-1 and FasL. However, treatment with the agonistic anti-Fas antibody showed that the enhanced surface Fas was not functional or was not enough to induce apoptosis and the C-33A/IL-18R cells escaped still resistant to Fas-mediated apoptosis. CONCLUSIONS: IL-18R transfection induced IL-18 expression and enhanced ROS and Fas expression in C-33A cells. These results show that C-33A/IL-18R cells escaped from immunuosurveillance by failure to express ICAM-1 adhesion molecules and Fas ligand, and are resistant to Fas-mediated apoptosis.