Enhanced caspase-8 recruitment to and activation at the DISC is critical for sensitisation of human hepatocellular carcinoma cells to TRAIL-induced apoptosis by chemotherapeutic drugs
Enhanced caspase-8 recruitment to and activation at the DISC is critical for sensitisation of human hepatocellular carcinoma cells to TRAIL-induced apoptosis by chemotherapeutic drugs
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DOI：
10.1038/sj.cdd.4401437
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发表时间：
2004-07-01
影响因子：
12.4
通讯作者：
Walczak, H
中科院分区：
文献类型：
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作者：
Ganten, TM;Haas, TL;Walczak, H
肿瘤坏死因子（TNF）相关凋亡诱导配体（TRAIL）在小鼠全身给药后显示出有效的抗肿瘤活性，而没有显示出用TNF家族的其他凋亡诱导成员如TNF和CD 95 L观察到的有害副作用。因此，TRAIL可能在人类癌症的治疗中具有巨大的潜力。然而，约60%的肿瘤细胞系对TRAIL不敏感。为了评估肿瘤对TRAIL的耐药机制，我们研究了对TRAIL表现出不同敏感性的肝细胞癌（HCC）细胞系。化疗药物预处理，例如，5-氟尿嘧啶（5-FU），使TRAIL耐药肝癌细胞系敏感的TRAIL诱导的凋亡。对TRAIL死亡诱导信号复合物（DISC）的分析揭示了TRAIL-R2的上调。Caspase-8的招聘和它的激活在DISC后，5-FU致敏显着增加，而FADD招聘基本保持不变。5-FU预处理下调细胞FLICE抑制蛋白（cFLIP），小干扰RNA的特异性cFLIP下调足以使TRAIL耐药肝癌细胞系对TRAIL诱导的细胞凋亡敏感。因此，5-FU致敏TRAIL的潜在机制是通过下调cFLIP促进caspase-8募集到DISC并在DISC处活化的有效性增加，以及随之发生的DISC处caspase-8与cFLIP比率的变化。
Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) exhibits potent antitumour activity upon systemic administration in mice without showing the deleterious side effects observed with other apoptosis-inducing members of the TNF family such as TNF and CD95L. TRAIL may, thus, have great potential in the treatment of human cancer. However, about 60% of tumour cell lines are not sensitive to TRAIL. To evaluate the mechanisms of tumour resistance to TRAIL, we investigated hepatocellular carcinoma (HCC) cell lines that exhibit differential sensitivity to TRAIL. Pretreatment with chemotherapeutic drugs, for example, 5-fluorouracil (5-FU), rendered the TRAIL-resistant HCC cell lines sensitive to TRAIL-induced apoptosis. Analysis of the TRAIL death-inducing signalling complex (DISC) revealed upregulation of TRAIL-R2. Caspase-8 recruitment to and its activation at the DISC were substantially increased after 5-FU sensitisation, while FADD recruitment remained essentially unchanged. 5-FU pretreatment downregulated cellular FLICE-inhibitory protein (cFLIP) and specific cFLIP downregulation by small interfering RNA was sufficient to sensitise TRAIL-resistant HCC cell lines for TRAIL-induced apoptosis. Thus, a potential mechanism for TRAIL sensitisation by 5-FU is the increased effectiveness of caspase-8 recruitment to and activation at the DISC facilitated by the downregulation of cFLIP and the consequent shift in the ratio of caspase-8 to cFLIP at the DISC.