title: PD-L1 is upregulated by EBV-driven LMP1 through NF-κB pathway and correlates with poor prognosis in natural killer/T-cell lymphoma.
abstract: Natural killer/T-cell lymphoma (NKTCL) is an Epstein-Barr virus (EBV)-associated, highly aggressive lymphoma. Treatment outcome remains sub-optimal, especially for advanced-stage or relapsed diseases. Programmed cell death receptor 1 (PD-1) and PD ligand 1 (PD-L1) have become promising therapeutic targets for various malignancies, but their role in the pathogenesis and their interactions with EBV in NKTCL remains to be investigated.
  
  
  
  Expression of PD-L1 was measured in NK-92 (EBV-negative) and SNK-6 (EBV-positive) cells by western blot, quantitative real-time PCR and enzyme-linked immunosorbent assay, and flow cytometry, respectively. Latent membrane protein 1 (LMP1)-harboring lentiviral vectors were transfected into NK-92 cells to examine the correlation between LMP1 and PD-L1 expression. Proteins in the downstream pathways of LMP1 signaling were measured in NK-92 cells transfected with LMP1-harboring or negative control vectors as well as in SNK-6 cells. PD-L1 expression on tumor specimens and serum concentration of soluble PD-L1 were collected in a retrospective cohort of patients with Ann Arbor stage I~II NKTCL, and their prognostic significance were analyzed.
  
  
  
  Expression of PD-L1 was significantly higher in SNK-6 cells than in NK-92 cells, at both protein and mRNA levels. Expression of PD-L1 was remarkably upregulated in NK-92 cells transfected with LMP1-harboring lentiviral vectors compared with those transfected with negative control vectors. Proteins in the MAPK/NF-κB pathway were upregulated in LMP1-expressing NK-92 cells compared with the negative control. Selective inhibitors of those proteins induced significant downregulation of PD-L1 expression in LMP1-expressing NK-92 cells as well as in SNK-6 cells. Patients with a high concentration of serum soluble PD-L1 (≥3.4 ng/ml) or with a high percentage of PD-L1 expression in tumor specimens (≥38 %) exhibited significantly lower response rate to treatment and remarkably worse survival, compared with their counterparts. A high concentration of serum soluble PD-L1 and a high percentage of PD-L1 expression in tumor specimens were independent adverse prognostic factors among patients with stage I~II NKTCL.
  
  
  
  PD-L1 expression positively correlated LMP1 expression in NKTCL, which was probably mediated by the MAPK/NF-κB pathway. PD-L1 expression in serum and tumor tissues has significant prognostic value for early-stage NKTCL.
authors.affiliation: Department of Hematologic Oncology, State Key Laboratory of Oncology in South China/Cancer Center, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou, Guangdong, 510060, People's Republic of China.|Department of Medical Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, People's Republic of China.
authors.forename: Xi-Wen
authors.initials: XW
authors.lastname: Bi
authors.affiliation: Department of Hematologic Oncology, State Key Laboratory of Oncology in South China/Cancer Center, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou, Guangdong, 510060, People's Republic of China.|Department of Hematologic Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, People's Republic of China.
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Hematologic Oncology, State Key Laboratory of Oncology in South China/Cancer Center, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou, Guangdong, 510060, People's Republic of China.|Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, People's Republic of China.
authors.forename: Wen-Wen
authors.initials: WW
authors.lastname: Zhang
authors.affiliation: Department of Hematologic Oncology, State Key Laboratory of Oncology in South China/Cancer Center, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou, Guangdong, 510060, People's Republic of China.|Department of Hematologic Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, People's Republic of China.
authors.forename: Jing-Hua
authors.initials: JH
authors.lastname: Wang
authors.affiliation: Department of Hematologic Oncology, State Key Laboratory of Oncology in South China/Cancer Center, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou, Guangdong, 510060, People's Republic of China.|Department of Hematologic Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, People's Republic of China.
authors.forename: Wen-Jian
authors.initials: WJ
authors.lastname: Liu
authors.affiliation: Department of Hematologic Oncology, State Key Laboratory of Oncology in South China/Cancer Center, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou, Guangdong, 510060, People's Republic of China.|Department of Hematologic Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, People's Republic of China.
authors.forename: Zhong-Jun
authors.initials: ZJ
authors.lastname: Xia
authors.affiliation: Department of Hematologic Oncology, State Key Laboratory of Oncology in South China/Cancer Center, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou, Guangdong, 510060, People's Republic of China.|Department of Medical Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, People's Republic of China.
authors.forename: Hui-Qiang
authors.initials: HQ
authors.lastname: Huang
authors.affiliation: Department of Hematologic Oncology, State Key Laboratory of Oncology in South China/Cancer Center, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou, Guangdong, 510060, People's Republic of China.|Department of Medical Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, People's Republic of China.
authors.forename: Wen-Qi
authors.initials: WQ
authors.lastname: Jiang
authors.affiliation: Department of Hematologic Oncology, State Key Laboratory of Oncology in South China/Cancer Center, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou, Guangdong, 510060, People's Republic of China.|Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, People's Republic of China.
authors.forename: Yu-Jing
authors.initials: YJ
authors.lastname: Zhang
authors.affiliation: Department of Hematologic Oncology, State Key Laboratory of Oncology in South China/Cancer Center, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou, Guangdong, 510060, People's Republic of China. wangliang@sysucc.org.cn.|Department of Hematologic Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, People's Republic of China. wangliang@sysucc.org.cn.
authors.forename: Liang
authors.initials: L
authors.lastname: Wang
mesh_terms: D060890:B7-H1 Antigen / Q000032:analysis* / Q000097:blood; D001706:Biopsy; D002478:Cells, Cultured; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D004854:Herpesvirus 4, Human; D054884:Host-Pathogen Interactions; D006801:Humans; D054391:Lymphoma, Extranodal NK-T-Cell / Q000175:diagnosis* / Q000473:pathology / Q000821:virology; D008297:Male; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism*; D011379:Prognosis; D014162:Transfection; D014763:Viral Matrix Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D060890:B7-H1 Antigen; C423236:CD274 protein, human; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D016328:NF-kappa B; D014763:Viral Matrix Proteins
keywords: Epstein–Barr virus; Latent membrane protein 1; Natural killer/T-cell lymphoma; Programmed cell death receptor 1