Song Jin H, Song Doyoun K, Herlyn Meenhard, Petruk Kenneth C, Hao Chunhai
Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada T6G 2S2.
Clin Cancer Res. 2003 Sep 15;9(11):4255-66.
Many melanoma cell lines and primary cultures are resistant to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. In this study, we investigated the molecular mechanisms that control melanoma cell resistance and searched for chemotherapeutic drugs that could overcome the TRAIL resistance in melanoma cells.
We examined 21 melanoma cell lines and 3 primary melanoma cultures for their sensitivity to TRAIL-induced apoptosis, and then tested cisplatin, chemptothecin, and etoposide for their synergistic effects on TRAIL sensitivity in resistant melanoma cells.
Of 21 melanoma cell lines, 11 showed various degrees of sensitivity to TRAIL-induced apoptosis through caspase-8-initiated cleavage of caspase-3 and DNA fragmentation factor 45. The remaining cell lines and primary cultures were resistant to TRAIL, but cisplatin, chemptothecin, and etoposide sensitized the resistant cell lines and primary cultures to TRAIL-induced apoptosis, which also occurred through the caspase-8-initiated caspase cascade. Of the two TRAIL death receptors (DR4 and DR5), melanoma cells primarily expressed DR5 on cell surface. Cisplatin treatment had no effects on cell surface DR5 expression or intracellular expression of Fas-associated death domain and caspase-8. Instead, cisplatin treatment down-regulated intracellular expression of the short form of cellular Fas-associated death domain-like interleukin-1beta-converting enzyme-like inhibitory protein (c-FLIP) and inhibited phosphorylation of the long form of c-FLIP.
The results presented here indicate that cisplatin inhibits c-FLIP protein expression and phosphorylation to restore TRAIL-induced caspase-8-initiated apoptosis in melanoma cells, thus providing a new combined therapeutic strategy for melanomas.
许多黑色素瘤细胞系和原代培养物对肿瘤坏死因子相关凋亡诱导配体（TRAIL）诱导的凋亡具有抗性。在本研究中，我们研究了控制黑色素瘤细胞抗性的分子机制，并寻找能够克服黑色素瘤细胞中TRAIL抗性的化疗药物。
我们检测了21种黑色素瘤细胞系和3种原发性黑色素瘤培养物对TRAIL诱导凋亡的敏感性，然后测试顺铂、喜树碱和依托泊苷对耐药黑色素瘤细胞中TRAIL敏感性的协同作用。
在21种黑色素瘤细胞系中，11种通过半胱天冬酶-8启动的半胱天冬酶-3切割和DNA片段化因子45对TRAIL诱导的凋亡表现出不同程度的敏感性。其余细胞系和原代培养物对TRAIL具有抗性，但顺铂、喜树碱和依托泊苷使耐药细胞系和原代培养物对TRAIL诱导的凋亡敏感，这也通过半胱天冬酶-8启动的半胱天冬酶级联反应发生。在两种TRAIL死亡受体（DR4和DR5）中，黑色素瘤细胞主要在细胞表面表达DR5。顺铂处理对细胞表面DR5表达或Fas相关死亡结构域和半胱天冬酶-8的细胞内表达没有影响。相反，顺铂处理下调了细胞Fas相关死亡结构域样白细胞介素-1β转换酶样抑制蛋白（c-FLIP）短形式的细胞内表达，并抑制了c-FLIP长形式的磷酸化。
本文结果表明，顺铂抑制c-FLIP蛋白表达和磷酸化，以恢复TRAIL诱导的黑色素瘤细胞中半胱天冬酶-8启动的凋亡，从而为黑色素瘤提供一种新的联合治疗策略。
