Human melanoma cells selected for resistance to apoptosis by prolonged exposure to tumor necrosis factor-related apoptosis-inducing ligand are more vulnerable to necrotic cell death induced by cisplatin.
OBJECTIVE
Heterogeneous sensitivity of melanoma cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis may lead to outgrowth of TRAIL-resistant cells and limit successful treatment by TRAIL. The present study aims to better understand the biological characteristics of melanoma cells resistant to TRAIL-induced apoptosis.


METHODS
We generated TRAIL-resistant melanoma cells by prolonged exposure to TRAIL and characterized the cells in terms of their sensitivity to killing induced by a panel of cytotoxic agents using biological and biochemical methods.


RESULTS
TRAIL-resistant melanoma cells are cross-resistant to apoptosis induced by another death ligand FasL, the DNA-damaging agent cisplatin, the histone deacetylase inhibitor suberic bishydroxamate, and the antimicrotubule Vinca alkaloid, vincristine. The apoptotic signaling seemed to be inhibited upstream of mitochondrial apoptotic events and was associated with decreased expression of multiple apoptotic mediators, including pro-caspase-8, Fas-associated death domain, Bid, Bim, p53, and the products of its proapoptotic target genes. Despite being resistant to apoptosis, TRAIL-resistant melanoma cells were more vulnerable to cisplatin-induced nonapoptotic cell death. This was characterized by lack of DNA fragmentation, delayed externalization of phosphatidylserine, caspase and p53 independence, and severe mitochondrial disruption, and was preceded by poly(ADP)ribose polymerase (PARP) activation and depletion of intracellular ATP, indicative of necrotic cell death. Inhibition of PARP activity partially converted the mode of cell death from necrosis to apoptosis.


CONCLUSIONS
TRAIL-resistant melanoma cells are cross-resistant to apoptosis induced by various apoptotic stimuli but are more sensitive to nonapoptotic cell death induced by cisplatin. Exploration of chemotherapy-induced nonapoptotic cell death may provide an alternative strategy in overcoming resistance of melanoma cells to TRAIL-induced apoptosis.
Immunology and Oncology Unit, Royal Newcastle Hospital, Newcastle, NSW, Australia.
Xu Dong
XD
Zhang
Jing Jing
JJ
Wu
Susan
S
Gillespie
Jodie
J
Borrow
Peter
P
Hersey
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism / Q000494:pharmacology*; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation / Q000187:drug effects; D053222:Fas Ligand Protein; D005434:Flow Cytometry; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008545:Melanoma / Q000378:metabolism / Q000473:pathology; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000502:physiology; D009336:Necrosis / Q000139:chemically induced; D011065:Poly(ADP-ribose) Polymerases; D011419:Propidium / Q000493:pharmacokinetics; D053221:TNF-Related Apoptosis-Inducing Ligand; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D048069:Tumor Necrosis Factors / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014750:Vincristine / Q000494:pharmacology
D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D048069:Tumor Necrosis Factors; D016159:Tumor Suppressor Protein p53; C493163:suberic bishydroxamate; D011419:Propidium; D014750:Vincristine; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D002945:Cisplatin