在人骨肉瘤细胞中，TRAIL介导的细胞凋亡过程中，Bid在半胱天冬酶-8激活的上游被切割。

Bid is cleaved upstream of caspase-8 activation during TRAIL-mediated apoptosis in human osteosarcoma cells.

作者信息

Garnett Theodore O, Filippova Maria, Duerksen-Hughes Penelope Jayne

机构信息

Department of Biochemistry and Microbiology, Loma Linda University School of Medicine, 11085 Campus Street, 121 Mortensen Hall, Loma Linda, CA, 92354, USA.

出版信息

Apoptosis. 2007 Jul;12(7):1299-315. doi: 10.1007/s10495-007-0058-8.

DOI:10.1007/s10495-007-0058-8

PMID:17431792

Abstract

TRAIL induces apoptosis in many malignant cell types. In this study, we used the human papilloma virus (HPV) 16 E6 protein as a molecular tool to probe the TRAIL pathway in HCT116 colon carcinoma cells and U2OS osteosarcoma cells. Intriguingly, we found that while E6 protected HCT116 cells from TRAIL, U2OS cells expressing E6 remained sensitive to TRAIL. Furthermore, silencing FADD and procaspase-8 expression with siRNA did not prevent TRAIL-induced apoptosis in U2OS cells. However, siBid provided significant protection from TRAIL, and the cleavage kinetics of Bid and caspase-8 revealed that Bid was cleaved prior to the activation of caspase-8. Cathepsin B activity in U2OS cells was significantly activated shortly after exposure to TRAIL, and the cathepsin B inhibitor, CA074Me, inhibited both TRAIL- and anti-DR5-mediated apoptosis and delayed the cleavage of Bid. These findings suggest that TRAIL activates a pathway dependent on Bid, but largely independent of FADD and caspase-8, in U2OS cells.

摘要

肿瘤坏死因子相关凋亡诱导配体（TRAIL）可诱导多种恶性细胞类型发生凋亡。在本研究中，我们使用人乳头瘤病毒（HPV）16 E6蛋白作为分子工具，来探究HCT116结肠癌细胞和U2OS骨肉瘤细胞中的TRAIL信号通路。有趣的是，我们发现，虽然E6可保护HCT116细胞免受TRAIL诱导的凋亡，但表达E6的U2OS细胞对TRAIL仍敏感。此外，用小干扰RNA（siRNA）沉默FADD和procaspase-8的表达并不能阻止TRAIL诱导U2OS细胞凋亡。然而，siBid可显著保护细胞免受TRAIL诱导的凋亡，Bid和caspase-8的切割动力学显示Bid在caspase-8激活之前被切割。U2OS细胞中的组织蛋白酶B活性在暴露于TRAIL后不久即被显著激活，组织蛋白酶B抑制剂CA074Me可抑制TRAIL和抗DR5介导的凋亡，并延迟Bid的切割。这些发现表明，在U2OS细胞中，TRAIL激活了一条依赖Bid，但很大程度上不依赖FADD和caspase-8的信号通路。