Kim Daejin, Hur Dae Young, Kim Yeong Seok, Lee Kyungmi, Lee Youngseon, Cho Daeho, Kang Jae Seung, Kim Young-in, Hahm Eunsil, Yang Yoolhee, Yoon Suyoung, Kim Seonghan, Lee Won Bok, Park Hae Young, Kim Yoon Berm, Hwang Young-il, Chang Ka Y, Lee Wang Jae
Department of Anatomy, Seoul National University, College of Medicine and Institute of Allergy and Clinical Immunology, Medical Research Center, Seoul National University, Seoul, South Korea.
Hum Immunol. 2002 Jul;63(7):576-87. doi: 10.1016/s0198-8859(02)00405-6.
Burkitt lymphoma (BL) is a tumor with the characteristics of germinal center B cells. We previously reported that the CM1 (centrocyte/-blast marker 1) molecule is expressed only in germinal center B cells, specifically, in a subpopulation of centroblasts and centrocytes. In the present study, we investigated the apoptosis induced by anti-CM1 in the Ramos and Raji human BL cell lines. The Ramos is protected from apoptosis by the crosslinking of sIgM and the calcium ionophore by the ligation of CD40 with anti-CD40 monoclonal antibodies (mAb) or soluble CD40 ligand (sCD40L). In this investigation on the effect of CM1 on apoptosis in BL cell lines, we found that cellular signaling by CM1 induces apoptosis and decreases cell viability, in BL cell lines cultured for 24 hours with protein-G agarose beads conjugated anti-CM1 mAb. Stimulation by CD40 ligated with sCD40L protected Raji cells from CM1-induced apoptosis, but did not protect Ramos cells. Furthermore, after anti-CM1 mAb stimulation, CD95 expression was upregulated and CD40 expression was unaltered or slightly decreased in Ramos cells, whereas CD95 was downregulated and CD40 was slightly upregulated in Raji cells. The engagement of CD40 by sCD40L enhanced CD95 expression, but the level of CM1 expression was unchanged in Ramos. However, sCD40L downregulated both CD95 and CM1 expression in Raji. In addition, the caspase-8 specific inhibitor blocked CM1-induced apoptosis in Ramos cells, but not in Raji cells. Increased mitochondrial membrane permeabilization was observed only in Raji cells. Moreover, the effector caspase inhibitor, z-DEVD, blocked CM1-mediated apoptosis in both cell lines. We found that CM1-induced apoptosis is achieved via different initiation pathways, which are cell-type dependent.
伯基特淋巴瘤（BL）是一种具有生发中心B细胞特征的肿瘤。我们之前报道过CM1（中心细胞/母细胞标志物1）分子仅在生发中心B细胞中表达，具体而言，在中心母细胞和中心细胞的一个亚群中表达。在本研究中，我们调查了抗CM1在拉莫斯（Ramos）和拉吉（Raji）人BL细胞系中诱导的凋亡情况。拉莫斯细胞通过sIgM交联以及用抗CD40单克隆抗体（mAb）或可溶性CD40配体（sCD40L）连接CD40与钙离子载体来保护自身免于凋亡。在这项关于CM1对BL细胞系凋亡影响的研究中，我们发现，在用与蛋白G琼脂糖珠偶联的抗CM1 mAb培养24小时的BL细胞系中，CM1的细胞信号传导诱导凋亡并降低细胞活力。用sCD40L连接的CD40刺激可保护拉吉细胞免于CM1诱导的凋亡，但不能保护拉莫斯细胞。此外，抗CM1 mAb刺激后，拉莫斯细胞中CD95表达上调，CD40表达未改变或略有下降，而在拉吉细胞中CD95下调，CD40略有上调。sCD40L与CD40的结合增强了拉莫斯细胞中CD95的表达，但CM1的表达水平未改变。然而，sCD40L下调了拉吉细胞中CD95和CM1的表达。此外，半胱天冬酶-8特异性抑制剂可阻断拉莫斯细胞中CM1诱导的凋亡，但不能阻断拉吉细胞中的凋亡。仅在拉吉细胞中观察到线粒体膜通透性增加。此外，效应半胱天冬酶抑制剂z-DEVD可阻断两种细胞系中CM1介导的凋亡。我们发现，CM1诱导的凋亡是通过不同的起始途径实现的，这些途径依赖于细胞类型。
