title: Ligation of CD47 induces G1 arrest in EBV-transformed B cells through ROS generation, p38 MAPK/JNK activation, and Tap73 upregulation.
abstract: 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.
authors.affiliation: *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.
authors.forename: Ga Bin
authors.initials: GB
authors.lastname: Park
authors.forename: Si Ra
authors.initials: SR
authors.lastname: Bang
authors.forename: Hyun-Kyung
authors.initials: HK
authors.lastname: Lee
authors.forename: Daejin
authors.initials: D
authors.lastname: Kim
authors.forename: Seonghan
authors.initials: S
authors.lastname: Kim
authors.forename: Jin Kyoung
authors.initials: JK
authors.lastname: Kim
authors.forename: Yeong Seok
authors.initials: YS
authors.lastname: Kim
authors.forename: Dae Young
authors.initials: DY
authors.lastname: Hur
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001402:B-Lymphocytes / Q000276:immunology* / Q000821:virology; D051928:CD47 Antigen / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002144:Callithrix; D002461:Cell Line, Transformed; D049109:Cell Proliferation / Q000187:drug effects; D050756:Cyclin-Dependent Kinase Inhibitor Proteins / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020031:Epstein-Barr Virus Infections / Q000276:immunology*; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D004854:Herpesvirus 4, Human / Q000276:immunology*; D006801:Humans; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D058990:Molecular Targeted Therapy; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D051928:CD47 Antigen; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D016213:Cyclins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D017382:Reactive Oxygen Species; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4