Anti-Fas/APO-1 antibody-mediated apoptosis of cultured human glioma cells. Induction and modulation of sensitivity by cytokines.

Abstract

Fas/APO-1 is a transmembrane protein of the nerve growth factor/TNFa receptor family which signals apoptotic cell death in susceptible target cells. We have investigated the susceptibility of seven human malignant glioma cell lines to Fas/APO-1-dependent apoptosis. Sensitivity to Fas/APO-1 antibody-mediated cell killing correlated with cell surface expression of Fas/APO-1. Expression of Fas/APO-1 as well as Fas/APO-1-dependent cytotoxicity were augmented by preexposure of human malignant glioma cells to IFNy and TNFa. Further, pretreatment with TGFp2, IL1 and IL8 enhanced Fas/APO-1 antibody-induced glioma cell apoptosis whereas other cytokines including TNFfi, IL6, macrophage colony-stimulating factor, IL10 and EL13 had no such effect. None of the human malignant glioma cell lines was susceptible to TNFa-induced cytotoxicity. Fas/ APO-1 antibody-sensitive glioma cell lines (n = 5), but not Fas/APO-1 antibody-resistant glioma cell lines (n = 2), became sensitive to TNFa when co-treated with inhibitors of RNA and protein synthesis. Resistance of human glioma cells to Fas/APO-1 antibody-mediated apoptosis was mainly related to low level expression of Fas/APO-1 and appeared not to be linked to overexpression of the antiapoptotic protooncogene, bcl-2. Given the resistance of human malignant glioma to surgery, irradiation, chemotherapy and immunotherapy, we propose that Fas/APO-1 may be a promising target for a novel locoregionary approach to human malignant glioma. This strategy gains support from the demonstration of Fas/APO-1 expression in ex vivo human malignant glioma specimens and from the absence of Fas/APO-1 in normal human brain parenchyma. (J. Clin. Invest. 1994. 94:954-964.)

Synthesis and biological effects of NO in malignant glioma cells: modulation by cytokines including CD95L and TGF-β dexamethasone, and p53 gene transfer

“…of nitrite in mM (n=3) Further, NO did not enhance CD95 expression in LN-229 cells (data not shown). In contrast, IFN-g as a positive control readily enhanced CD95 expression (Weller et al, 1994). This e ect was una ected by L-NMMA ( Figure 2f).…”

“…(f) LN-229 cells were either untreated or exposed to IFN-g (100 U/ml) in the absence or presence of L-NMMA (1 mM). CD95 expression was assessed by¯ow cytometry (Weller et al, 1994) (open curves, isotype control antibody, ®lled curves, CD95 antibody) …”

“…Apoptosis of human malignant glioma cells can be induced by exposure to agonistic antibodies to the cytokine receptor, CD95, or exposure to the natural CD95 ligand (CD95L) (Weller et al, 1994(Weller et al, , 1995bWagenknecht et al, 1997a). Here, we characterized NO synthesis and biological e ects of exogenous NO in these cells and asked whether NO plays a role in CD95-mediated apoptosis of glioma cells.…”

“…Here, we characterized NO synthesis and biological e ects of exogenous NO in these cells and asked whether NO plays a role in CD95-mediated apoptosis of glioma cells. Rationales for this study included the following observations: (i) CD95-mediated apoptosis is potentiated by cytokines such as IFN-g and TNF-a (Weller et al, 1994) which also induce NO release (Kilbourn and Belloni, 1990),…”

“…(ii) CD95-mediated apoptosis is inhibited by DEX (Weller et al, 1994), a drug that prevents iNOS activation (Wu et al, 1995;Radomski et al, 1990), (iii) NO enhances CD95 expression in vascular smooth muscle cells (Fukuo et al, 1996).…”