1. Intracellular regulation of TRAIL-induced apoptosis in human melanoma cells.
- Author
-
Griffith TS, Chin WA, Jackson GC, Lynch DH, and Kubin MZ
- Subjects
- Amino Acid Sequence, Apoptosis Regulatory Proteins, CASP8 and FADD-Like Apoptosis Regulating Protein, Carrier Proteins physiology, Cysteine Endopeptidases drug effects, Cysteine Endopeptidases metabolism, Cysteine Endopeptidases physiology, Enzyme Activation drug effects, Enzyme Activation immunology, Humans, Immunity, Innate, Intracellular Fluid enzymology, Intracellular Fluid immunology, Ligands, Melanoma enzymology, Melanoma immunology, Membrane Glycoproteins metabolism, Molecular Sequence Data, Polymerase Chain Reaction, Protein Synthesis Inhibitors pharmacology, Receptors, Tumor Necrosis Factor biosynthesis, TNF-Related Apoptosis-Inducing Ligand, Tumor Cells, Cultured, Tumor Necrosis Factor-alpha metabolism, Apoptosis immunology, Intracellular Fluid metabolism, Intracellular Signaling Peptides and Proteins, Melanoma pathology, Membrane Glycoproteins physiology, Tumor Necrosis Factor-alpha physiology
- Abstract
The observation that TNF-related apoptosis-inducing ligand (TRAIL), a member of the TNF cytokine family, induces apoptosis in a number of different tumor cell types led us to compare the tumoricidal effects of TRAIL to those of other TNF family molecules on human melanoma cells. We found that a high proportion of the melanoma cell lines tested were killed by TRAIL, whereas all the melanoma lines were resistant to the other TNF family cytokines tested. TRAIL-induced death was characterized by caspase activation and cellular protein cleavage within minutes of TRAIL addition, and death could be completely inhibited by the caspase inhibitors Ile-Glu-Thr-Asp (IETD) and Val-Ala-Asp (VAD), indicating the presence of a TRAIL receptor signaling pathway similar to that identified for Fas and TNF receptors. Specific TRAIL receptor expression was determined by RT-PCR, and the presence of mRNA encoding the "protective" TRAIL receptors did not correspond to resistance or sensitivity to TRAIL-induced apoptosis. Addition of protein synthesis inhibitors to TRAIL-resistant melanomas rendered them sensitive to TRAIL, indicating that the presence or the absence of intracellular apoptosis inhibitors may mediate resistance or sensitivity to TRAIL-mediated apoptosis. Expression of one such inhibitor, FLICE-inhibitory protein (FLIP), was highest in the TRAIL-resistant melanomas, while being low or undetectable in the TRAIL-sensitive melanomas. Furthermore, addition of actinomycin D to TRAIL-resistant melanomas resulted in decreased intracellular concentrations of FLIP, which correlated with their acquisition of TRAIL sensitivity. Collectively, our results indicate that TRAIL-induced apoptosis occurs through a caspase signaling cascade and that resistance is controlled by intracellular regulators of apoptosis.
- Published
- 1998