Targeting the short form of cFLIP by RNA interference is sufficient to enhance TRAIL sensitivity in PC3 prostate carcinoma cells
Targeting the short form of cFLIP by RNA interference is sufficient to enhance TRAIL sensitivity in PC3 prostate carcinoma cells
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DOI：
10.4161/cbt.5.12.3352
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发表时间：
2006-12-01
影响因子：
3.6
通讯作者：
Voelkel-Johnson, Christina
中科院分区：
文献类型：
--
作者：
White, Shai J.;Lu, Ping;Voelkel-Johnson, Christina
促凋亡死亡受体配体肿瘤坏死因子相关凋亡诱导配体（TRAIL）作为一种新型癌症治疗剂受到了广泛关注，因为它选择性诱导恶性细胞而非正常细胞的凋亡。不幸的是，前列腺癌细胞对 TRAIL 诱导的细胞凋亡几乎没有表现出任何敏感性。然而，多柔比星增强了对 TRAIL 的敏感性，这与 caspase-8 抑制剂 cFLIP 表达的减少相关（Kelly 等人，Cancer Biol Ther 1：520）。在这项研究中，我们发现阿霉素会诱导 cFLIP 蛋白的时间和剂量依赖性损失，但不影响稳态 mRNA 水平。在阿霉素存在下，蛋白酶体抑制可稳定 cFLIP(L)。尽管蛋白酶体抑制剂增加了短 cFLIP 亚型的基础水平，但在阿霉素治疗期间，在蛋白酶体抑制作用不存在或存在的情况下，cFLIP(S) 以相似的速率下降。在阿霉素不存在或存在的情况下，cFLIP(S)GFP 融合蛋白的异位表达可保护 PC3 细胞免受 TRAIL 诱导的细胞凋亡，而通过 RNA 干扰下调 cFLIP(S) 会导致对 TRAIL 诱导的细胞凋亡敏感。我们得出的结论是，阿霉素介导的 cFLIP(S) 下调发生在转录后水平，与蛋白酶体介导的途径无关，足以增强 PC3 前列腺癌细胞中的 TRAIL 敏感性。
The pro-apoptotic death receptor ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has received significant attention as a novel cancer therapeutic, since it selectively induces apoptosis in malignant and not normal cells. Unfortunately, prostate cancer cells display little if any susceptibility to TRAIL-induced apoptosis. However, sensitivity to TRAIL is enhanced by doxorubicin, which correlated with a decrease in expression of the caspase-8 inhibitor cFLIP (Kelly et al., Cancer Biol Ther 1: 520). In this study we show that doxorubicin induces a time- and dose-dependent loss of cFLIP protein, but does not affect steady-state mRNA levels. Proteasome inhibition stabilized cFLIP(L) in the presence of doxorubicin. Although proteasome inhibitors increased basal levels of short cFLIP isoforms, cFLIP(S) declined at a similar rate in the absense or presence of proteasome inhibition during doxorubicin treatment. Ectopic expression of a cFLIP(S)GFP fusion protein protected PC3 cells from TRAIL-induced apoptosis in the absence or presence of doxorubicin, whereas downregulation of cFLIP(S) by RNA interference resulted in sensitization to TRAIL-induced apoptosis. We conclude that doxorubicin-mediated downregulation of cFLIP(S), which occurs at the post-transcriptional level independent of proteasome-mediated pathways, is sufficient to enhance TRAIL sensitivity in PC3 prostate carcinoma cells.