Caspase-8 levels affect necessity for mitochondrial amplification in death ligand-induced glioma cell apoptosis
Details
Publication Year 2004-03,Volume 39,Issue #3,Page 173-182
Journal Title
MOLECULAR CARCINOGENESIS
Publication Type
Journal Article
Abstract
Fifty percent of high-grade glioma patients die within a year of diagnosis and less than two percent survive five years postdiagnosis. Elucidating apoptosis signaling pathways may assist in designing better adjuvant therapies. Preliminary characterizations suggested that glioma cells may either employ mitochondrial-independent or -dependent death receptor-induced apoptotic pathways, characteristic of cells termed type I and type II, respectively. In the present study, we generated panels of clonal transfectants overexpressing various levels of Bcl-2, in two parental glioma cell lines. These cells were used to explore molecular factors determining the necessity for mitochondrial amplification of death receptor signaling. Moderate 3cl-2 expression was sufficient to render one glioma cell line (D270) resistant to apoptosis induced by Fas ligand or TRAIL, consistent with these cells being type II. However, expression of even very high levels of Bcl-2 in a second line (D645) did not affect death ligand sensitivity, indicative of a type I phenotype. D270 cells expressed much less caspase-8 protein than D645 cells. Enforced overexpression of caspase-8 (or cytoplasmic Diablo/Smac) in D270 cells overcame 3cI-2 inhibition of death ligand-induced apoptosis, converting them from type II to type I. This indicates that caspase-8 levels can influence the requirement for mitochondrial involvement in death receptor apoptotic signaling in glioma cells. (C) 2004 Wiley-Liss, Inc.
Publisher
WILEY-LISS
Keywords
RECEPTOR-MEDIATED APOPTOSIS; MALIGNANT GLIOMA; CD95-MEDIATED APOPTOSIS; CANCER CELLS; CYTOCHROME-C; RELEASE; TRAIL; BCL-2; SMAC/DIABLO; INHIBITION
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Creation Date: 2004-03-01 12:00:00
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