Park Ga Bin, Bang Si Ra, Lee Hyun-Kyung, Kim Daejin, Kim Seonghan, Kim Jin Kyoung, Kim Yeong Seok, Hur Dae Young
*Department of Anatomy and Research Center for Tumor Immunology, Inje University College of Medicine ‡Department of Internal Medicine, Inje University Busan Paik Hospital, Busan †Department of Anesthesiology, Inje University Seoul Paik Hospital §Department of Anesthesiology, Samsung Medical Center, Sungkyunkwan University, Seoul , Republic of Korea.
J Immunother. 2014 Jul-Aug;37(6):309-20. doi: 10.1097/CJI.0000000000000042.
CD47 is expressed in normal activated cells as well as in several tumors. It also has been implicated as having antiangiogenic and antimetastatic properties, but its roles in Epstein-Barr virus (EBV)-transformed B cells are still not fully understood. Herein, we report that EBV infection induced CD47 surface expression on B cells, and CD47 ligation with anti-CD47 mAb (B6H12) reduced cell proliferation and induced G1 arrest. CD47-induced G1 arrest was mediated through increased cyclin-dependent kinase inhibitors (CDKi) and a simultaneously decreased CDK/cyclins, and p38 MAPK/JNK activation preceded binding of CDKi-CDK. Moreover, reactive oxygen species (ROS) generation and upregulation of both TAp73 and ER stress sensor proteins were detected after CD47 ligation, and p38 inhibitor SB203580 and JNK inhibitor SP600125 blocked upregulation of TAp73 and cell cycle arrest. We investigated whether ROS generation is the initial event of CD47-mediated G1 arrest because ROS scavenger NAC effectively abrogated the majority of CD47-mediated responses but SB203580 and SP600125 did not block ROS production. Taken together, we concluded that CD47 ligation on EBV-transformed B cells led to G1 arrest by ROS generation and, subsequently, there was p38 MAPK/JNK pathway activation, ER stress triggering, and TAp73 upregulation. Our findings provide data supporting CD47 as a feasible target for EBV-associated tumor therapy.
CD47在正常活化细胞以及多种肿瘤中均有表达。它还被认为具有抗血管生成和抗转移特性，但其在爱泼斯坦-巴尔病毒（EBV）转化的B细胞中的作用仍未完全明确。在此，我们报告EBV感染可诱导B细胞表面表达CD47，且抗CD47单克隆抗体（B6H12）与CD47结合可降低细胞增殖并诱导G1期阻滞。CD47诱导的G1期阻滞是通过细胞周期蛋白依赖性激酶抑制剂（CDKi）增加以及同时的细胞周期蛋白依赖性激酶/细胞周期蛋白减少介导的，并且p38丝裂原活化蛋白激酶/应激活化蛋白激酶（JNK）的激活先于CDKi与细胞周期蛋白依赖性激酶的结合。此外，在CD47结合后检测到活性氧（ROS）生成以及TAp73和内质网应激传感器蛋白的上调，并且p38抑制剂SB203580和JNK抑制剂SP600125可阻断TAp73的上调和细胞周期阻滞。我们研究了ROS生成是否是CD47介导的G1期阻滞的初始事件，因为ROS清除剂NAC有效地消除了大多数CD47介导的反应，但SB203580和SP600125并未阻断ROS的产生。综上所述，我们得出结论，EBV转化的B细胞上的CD47结合通过ROS生成导致G1期阻滞，随后有p38丝裂原活化蛋白激酶/应激活化蛋白激酶途径激活、内质网应激触发以及TAp73上调。我们的研究结果提供了支持CD47作为EBV相关肿瘤治疗可行靶点的数据。
