We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Ordering of ceramide formation, caspase activation, and Bax/Bcl-2 expression during etoposide-induced apoptosis in C6 glioma cells.
- Authors
Sawada, M; Nakashima, S; Banno, Y; Yamakawa, H; Hayashi, K; Takenaka, K; Nishimura, Y; Sakai, N; Nozawa, Y
- Abstract
Etoposide (VP-16) a topoisomerase II inhibitor induces apoptosis of tumor cells. The present study was designed to elucidate the mechanisms of etoposide-induced apoptosis in C6 glioma cells. Etoposide induced increased formation of ceramide from sphingomyelin and release of mitochondrial cytochrome c followed by activation of caspase-9 and caspase-3, but not caspase-1. In addition, exposure of cells to etoposide resulted in decreased expression of Bcl-2 with reciprocal increase in Bax protein, z-VAD·FMK, a broad spectrum caspase inhibitor, failed to suppress the etoposide-induced ceramide formation and change of the Bax/Bcl2 ratio, although it did inhibit etoposide-induced death of C6 cells. Reduced glutathione or N-acetylcysteine, which could reduce ceramide formation by inhibiting sphingomyelinase activity, prevented C6 cells from etoposide-induced apoptosis through blockage of caspase-3 activation and change of the Bax/Bcl-2 ratio. In contrast, the increase in ceramide level by an inhibitor of ceramide glucosyltransferase-1, D-threo-1-phenyl-2-decanoylamino-3-morpholino-1propanol caused elevation of the Bax/Bcl-2 ratio and potentiation of caspase-3 activation, thereby resulting in enhancement of etoposide-induced apoptosis. Furthermore, cell-permeable exogenous ceramides (C[sub 2]- and C[sub 6]-ceramide) induced downregulation of Bcl-2, leading to an increase in the Bax/Bcl-2 ratio and subsequent activation of caspases-9 and -3. Taken together, these results suggest that ceramide may function as a mediator of etoposide-induced apoptosis of C6 glioma cells, which induces increase in the Bax/Bcl-2 ratio followed by release of cytochrome c leading to caspases-9 and -3 activation.
- Subjects
APOPTOSIS; PROTEOLYTIC enzymes; CERAMIDES; GLIOMAS
- Publication
Cell Death & Differentiation, 2000, Vol 7, Issue 9, p761
- ISSN
1350-9047
- Publication type
Article
- DOI
10.1038/sj.cdd.4400711