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Variable expression of protein kinase C epsilon in human melanoma cells regulates sensitivity to TRAIL-induced apoptosis.
- Source :
-
Molecular cancer therapeutics [Mol Cancer Ther] 2005 Apr; Vol. 4 (4), pp. 668-76. - Publication Year :
- 2005
-
Abstract
- Protein kinase C (PKC) activation is believed to protect against apoptosis induced by death receptors. We have found however that the effect of activation of PKC on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis of melanoma differs between cell lines. Pretreatment with phorbol 12-myristate 13-acetate (PMA) led to inhibition of apoptosis in the majority of the melanoma cell lines, but those with relatively low PKC epsilon expression were sensitized to TRAIL-induced apoptosis. Introduction of PKC epsilon into PKC epsilon-low cell lines reversed sensitization of the cells to TRAIL-induced apoptosis by PMA. In contrast, a dominant-negative form of PKC epsilon caused an increase in sensitivity. The changes in sensitivity to TRAIL-induced apoptosis were reflected in similar changes in conformation of Bax and its relocation from the cytosol to mitochondria. Similarly, there were concordant increases or decreases in mitochondrial release of second mitochondria-derived activator of caspase/DIABLO, activation of caspase-3, and processing of its substrates. Activation of PKC seemed to mediate its effects upstream of mitochondria but downstream of caspase-8 and Bid in that pretreatment with PMA did not cause significant changes in the expression levels of TRAIL death receptors, alterations in the levels of caspase-8 activation, or cleavage of Bid. PKC activated the anti-apoptotic extracellular signal-regulated kinase 1/2 pathway, but inhibitors of this pathway only partially reversed the protective effect of PKC against TRAIL-induced apoptosis. These results provide further insights into the variable responses of melanoma to TRAIL-induced apoptosis and may help define responsive phenotypes to treatment of melanoma with TRAIL.
- Subjects :
- Adenoviridae genetics
Apoptosis Regulatory Proteins
Blotting, Western
Caspase 3
Caspase 8
Caspases metabolism
Cell Line, Tumor
Cytosol metabolism
Flow Cytometry
Genetic Vectors
Humans
Melanoma metabolism
Mitochondria metabolism
Mitochondria pathology
Phenotype
Plasmids metabolism
Protein Conformation
Protein Kinase C-epsilon
Proto-Oncogene Proteins c-bcl-2 metabolism
Recombinant Proteins chemistry
TNF-Related Apoptosis-Inducing Ligand
Tetradecanoylphorbol Acetate pharmacology
Transfection
bcl-2-Associated X Protein
Apoptosis
Gene Expression Regulation, Enzymologic
Gene Expression Regulation, Neoplastic
Melanoma enzymology
Melanoma pathology
Membrane Glycoproteins metabolism
Protein Kinase C biosynthesis
Tumor Necrosis Factor-alpha metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1535-7163
- Volume :
- 4
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Molecular cancer therapeutics
- Publication Type :
- Academic Journal
- Accession number :
- 15827341
- Full Text :
- https://doi.org/10.1158/1535-7163.MCT-04-0332