Induction of apoptosis by IFNγ in human neuroblastoma cell lines through the CD95/CD95L autocrine circuit

Abstract

The CD95 (APO-1/Fas) system can mediate apoptosis in immune cells as well as in tumour cells, where it may contribute to tumour immune-escape. On the other hand, its induction by anticancer drugs may lead to tumour reduction. Interferong (IFNg) increases the sensitivity of tumour cell lines to anti-CD95 antibody-mediated apoptosis. We describe induction of apoptosis by IFNg through the expression of CD95 and its ligand (CD95L) in human neuroblastoma cell lines. Neuroblastoma cells showed low constitutive expression of CD95 and CD95L. Subsequent to IFNg-modulated increase in CD95 and CD95L mRNA as well as protein levels, apoptosis was observed. Our results demonstrated that cytokine-mediated apoptosis was mediated through the activation of the CD95/CD95L autocrine circuit since: (i) cell death occurred following CD95/CD95L expression and correlated with CD95 and CD95L expression levels, (ii) failed to occur in a clone which weakly upregulated CD95 and lacked CD95L induction after IFNg stimulation, (iii) was at least partially inhibited by using blocking F(ab') 2 anti-CD95 antibody fragments and the recombinant Fas-Fc protein, that prevented the interaction between CD95 and CD95L. The intracellular molecular mechanisms elicited by IFNg are clearly highly complex, with several signalling pathways being activated, including the CD95 system. These findings suggest that IFNg may have a significant potential in the therapy of neuroblastoma in vivo.

Silencing of death receptor and caspase-8 expression in small cell lung carcinoma cell lines and tumors by DNA methylation

“…Treatment of neuroblastoma cells with either the demethylating drug 5-AzaC or IFNg has been shown in previous studies to induce caspase-8 and Fas expression and to sensitize them to death-receptor-induced death. 14,16,17 In SCLC cells that are silenced for caspase-8, Fas and TRAIL-R1 expression, treatment with both 5-AzaC and IFNg was necessary to induce sufficient expression of caspase-8, Fas and TRAIL to reduce their resistance to Fas and TRAILinduced death. Unfortunately, the use of demethylating agents such as 5-AzaC for cancer therapy is limited by toxic side effects; therefore, the development of novel agents that more specifically inhibit the expression of DNA methyltransferases in tumor cells and their use in combination with IFNg and TRAIL is worthwhile.…”

Ataxin-2 promotes apoptosis of human neuroblastoma cells

“…IFNg-induced changes in gene expression may cooperate with ataxin-2 in triggering apoptosis. IFNg was reported to activate the CD95 system in neuroblastoma cells (Bernassola et al, 1999;Annicchiarico-Petruzzelli et al, 2001), and several IFNg targets like PKR (Gil and Esteban, 2000) and DAP kinase (Cohen et al, 1997) have a proapoptotic function.…”

IFN-γ Induces the Apoptosis of WEHI 279 and Normal Pre-B Cell Lines by Expressing Direct Inhibitor of Apoptosis Protein Binding Protein with Low pI

“…The OD at 405 nm was measured using a microplate reader. (23)(24)(25)(26). Besides this receptor-mediated apoptosis, FADD-mediated activation of death receptors, and the expression of caspase-1 also have been reported (31)(32)(33).…”