Zhang Xu Dong, Wu Jing Jing, Gillespie Susan, Borrow Jodie, Hersey Peter
Immunology and Oncology Unit, Royal Newcastle Hospital, Newcastle, NSW, Australia.
Clin Cancer Res. 2006 Feb 15;12(4):1355-64. doi: 10.1158/1078-0432.CCR-05-2084.
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.
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.
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.
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.
黑色素瘤细胞对肿瘤坏死因子相关凋亡诱导配体（TRAIL）诱导的凋亡具有异质性敏感性，这可能导致TRAIL抗性细胞的生长，并限制TRAIL治疗的成功。本研究旨在更好地了解对TRAIL诱导凋亡具有抗性的黑色素瘤细胞的生物学特性。
我们通过长时间暴露于TRAIL产生了对TRAIL具有抗性的黑色素瘤细胞，并使用生物学和生化方法，根据它们对一组细胞毒性药物诱导杀伤的敏感性对这些细胞进行了表征。
对TRAIL具有抗性的黑色素瘤细胞对另一种死亡配体FasL、DNA损伤剂顺铂、组蛋白去乙酰化酶抑制剂辛二酰双羟肟酸以及抗微管长春花生物碱长春新碱诱导的凋亡具有交叉抗性。凋亡信号似乎在线粒体凋亡事件的上游受到抑制，并且与多种凋亡介质的表达降低有关，包括前半胱天冬酶-8、Fas相关死亡结构域、Bid、Bim、p53及其促凋亡靶基因的产物。尽管对凋亡具有抗性，但对TRAIL具有抗性的黑色素瘤细胞更容易受到顺铂诱导的非凋亡性细胞死亡的影响。这表现为缺乏DNA片段化、磷脂酰丝氨酸的外化延迟、不依赖半胱天冬酶和p53，以及严重的线粒体破坏，并且在聚（ADP）核糖聚合酶（PARP）激活和细胞内ATP耗竭之前发生，这表明细胞发生坏死性死亡。抑制PARP活性部分地将细胞死亡模式从坏死转变为凋亡。
对TRAIL具有抗性的黑色素瘤细胞对各种凋亡刺激诱导的凋亡具有交叉抗性，但对顺铂诱导的非凋亡性细胞死亡更敏感。探索化疗诱导的非凋亡性细胞死亡可能为克服黑色素瘤细胞对TRAIL诱导凋亡的抗性提供一种替代策略。
