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Cystatin B inhibition of TRAIL-induced apoptosis is associated with the protection of FLIP(L) from degradation by the E3 ligase itch in human melanoma cells.
- Source :
-
Cell death and differentiation [Cell Death Differ] 2010 Aug; Vol. 17 (8), pp. 1354-67. Date of Electronic Publication: 2010 Mar 19. - Publication Year :
- 2010
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Abstract
- Past studies have identified a number of distinct mechanisms that contribute to the resistance of melanoma cells against apoptosis induced by TNF-related apoptosis-inducing ligand (TRAIL). In this report we show that cystatin B is another endogenous inhibitor of TRAIL-induced apoptosis. Cystatin B-deficient melanoma cell lines established by shRNA knockdown displayed increased apoptosis that was associated with enhanced activation of caspase-8 induced by TRAIL. This was not related to the inhibitory effect of cystatin B on the lysosomal cysteine proteases, cathepsin B and L, as they did not have a role in TRAIL-induced apoptosis in most melanoma cell lines even when cystatin B was inhibited. Instead, sensitization of melanoma cells to TRAIL-induced apoptosis by inhibition of cystatin B appeared associated with decreased stability of FLIP(L) as the levels of FLIP(L) were reduced because of shortened half-life time in melanoma cells deficient in cystatin B. In contrast, over-expression of cystatin B increased the levels of FLIP(L), decreased the amount of the E3 ligase Itch associated with FLIP(L), and reduced FLIP(L) ubiquitination. Inhibition of Itch by siRNA restored the levels of FLIP(L) and blocked sensitization to TRAIL-induced apoptosis associated with deficiency in cystatin B. Taken together, these results indicate that cystatin B regulates Itch-mediated degradation of FLIP(L) and thereby TRAIL-induced apoptosis in melanoma cells.
- Subjects :
- Caspase 8 metabolism
Cell Line, Tumor
Cystatin B genetics
Gene Knockdown Techniques
Humans
Melanoma enzymology
RNA Interference
RNA, Small Interfering metabolism
Apoptosis
CASP8 and FADD-Like Apoptosis Regulating Protein metabolism
Cystatin B metabolism
Melanoma metabolism
Repressor Proteins metabolism
TNF-Related Apoptosis-Inducing Ligand pharmacology
Ubiquitin-Protein Ligases metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1476-5403
- Volume :
- 17
- Issue :
- 8
- Database :
- MEDLINE
- Journal :
- Cell death and differentiation
- Publication Type :
- Academic Journal
- Accession number :
- 20300110
- Full Text :
- https://doi.org/10.1038/cdd.2010.29