Nakayama Masafumi, Ishidoh Kazumi, Kayagaki Nobuhiko, Kojima Yuko, Yamaguchi Noriko, Nakano Hiroyasu, Kominami Eiki, Okumura Ko, Yagita Hideo
Department of Immunology, Allergy Research Center, Division of Pathology, Central Laboratory of Medical Sciences, Juntendo University School of Medicine, Tokyo, Japan.
J Immunol. 2002 Jan 15;168(2):734-43. doi: 10.4049/jimmunol.168.2.734.
TWEAK, a recently identified member of the TNF family, is expressed on IFN-gamma-stimulated monocytes and induces cell death in certain tumor cell lines. In this study, we characterized the TWEAK-induced cell death in several tumor cell lines that exhibited distinct features. Although the TWEAK-induced cell death in Kym-1 cells was indirectly mediated by TNF-alpha and was inhibited by cycloheximide, the TWEAK-induced cell death in HSC3 cells or IFN-gamma-treated HT-29 cells was not inhibited by anti-TNF-alpha mAb or cycloheximide, suggesting a direct triggering of cell death via TWEAK receptor in the latter cell lines. The TWEAK-induced apoptosis in HSC3 cells and IFN-gamma-treated HT-29 cells was associated with caspase-8 and caspase-3 activation. Although a pan-caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone, inhibited the TWEAK-induced cell death in HSC3 cells, it rather sensitized HT-29 cells to TWEAK-induced cell death by necrosis. This necrosis was abrogated by lysosomal proteinase inhibitors, particularly a cathepsin B inhibitor, [L-3-trans-(propylcarbamoyl)oxirane-2-carbonyl]-L-isoleucyl-L-proline methyl ester. During the process of TWEAK-induced necrosis, cathepsin B was released from lysosome to cytosol. Although DR3 has been reported to be a receptor for TWEAK, all TWEAK-sensitive tumor cell lines used in this study did not express DR3 at either protein or mRNA level, but did bind CD8-TWEAK specifically. These results indicated that TWEAK could induce multiple pathways of cell death, including both caspase-dependent apoptosis and cathepsin B-dependent necrosis, in a cell type-specific manner via TWEAK receptor(s) distinct from DR3.
肿瘤坏死因子样弱凋亡诱导因子（TWEAK）是肿瘤坏死因子（TNF）家族中最近发现的成员，在γ干扰素刺激的单核细胞上表达，并能诱导某些肿瘤细胞系发生细胞死亡。在本研究中，我们对TWEAK在几种具有不同特征的肿瘤细胞系中诱导的细胞死亡进行了特性分析。虽然TWEAK在Kym-1细胞中诱导的细胞死亡是由肿瘤坏死因子-α（TNF-α）间接介导的，并被放线菌酮抑制，但TWEAK在HSC3细胞或经γ干扰素处理的HT-29细胞中诱导的细胞死亡不受抗TNF-α单克隆抗体或放线菌酮的抑制，这表明在后者的细胞系中，细胞死亡是通过TWEAK受体直接触发的。TWEAK在HSC3细胞和经γ干扰素处理的HT-29细胞中诱导的凋亡与半胱天冬酶-8（caspase-8）和半胱天冬酶-3（caspase-3）的激活有关。虽然一种泛半胱天冬酶抑制剂，苄氧羰基-缬氨酸-丙氨酸-天冬氨酸-氟甲基酮，抑制了TWEAK在HSC3细胞中诱导细胞死亡，但它反而使HT-29细胞对TWEAK诱导的坏死性细胞死亡更加敏感。这种坏死被溶酶体蛋白酶抑制剂，特别是组织蛋白酶B抑制剂[L-3-反式-（丙基氨基甲酰基）环氧乙烷-2-羰基]-L-异亮氨酰-L-脯氨酸甲酯消除。在TWEAK诱导坏死的过程中，组织蛋白酶B从溶酶体释放到细胞质中。虽然已有报道称死亡受体3（DR3）是TWEAK的受体，但本研究中使用的所有对TWEAK敏感的肿瘤细胞系在蛋白质或mRNA水平均不表达DR3，但确实能特异性结合CD8-TWEAK。这些结果表明，TWEAK可通过不同于DR3的TWEAK受体，以细胞类型特异性的方式诱导多种细胞死亡途径，包括半胱天冬酶依赖性凋亡和组织蛋白酶B依赖性坏死。
