Intracellular Regulation of TRAIL-Induced Apoptosis in Human Melanoma Cells

• Published in: The Journal of immunology (1950) 1998-09, Vol.161 (6), p.2833-2840
• Main Authors: Griffith, Thomas S, Chin, Wilson A, Jackson, Glenn C, Lynch, David H, Kubin, Marek Z
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Apoptosis - immunology; Apoptosis Regulatory Proteins; Carrier Proteins - physiology; CASP8 and FADD-Like Apoptosis Regulating Protein; 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; Intracellular Fluid - metabolism; Intracellular Signaling Peptides and Proteins; Ligands; Melanoma - enzymology; Melanoma - immunology; Melanoma - pathology; Membrane Glycoproteins - metabolism; Membrane Glycoproteins - physiology; 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; Tumor Necrosis Factor-alpha - physiology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.161.6.2833

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.