PD-L1 is upregulated by EBV-driven LMP1 through NF-κB pathway and correlates with poor prognosis in natural killer/T-cell lymphoma

Abstract

BackgroundNatural 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.MethodsExpression 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.ResultsExpression 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.ConclusionsPD-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.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-016-0341-7) contains supplementary material, which is available to authorized users.

The perivascular microenvironment in Epstein–Barr virus positive primary central nervous system lymphoma: The role of programmed cell death 1 and programmed cell death ligand 1

“…In addition, Green et al demonstrated that PD‐L1 in lymphoblastoid cells was up‐regulated through an LMP‐1‐mediated activation of STAT3 (signal transducer and activator of transcription 3), AP‐1 (activator protein 1), and NFκB (nuclear factor kappa B) . Furthermore, Bi et al reported that PD‐L1 was upregulated in NK/T‐cell lymphoma by an EBV‐driven activation of LMP1 and the NF‐κB pathway, and that this correlated with poor prognosis . These data indicate that EBV‐driven LMP‐1 activation could up‐regulate PD‐L1 in EBV‐positive PCNSLs, and we have previously reported that LMP‐1 gene deletion and EBV‐nuclear antigen 2 (EBNA‐2) expression are important tumorigenic factors for EBV‐positive PCNSL in immunocompetent elderly patients .…”

“…22 Furthermore, Bi et al reported that PD-L1 was upregulated in NK/T-cell lymphoma by an EBVdriven activation of LMP1 and the NF-κB pathway, and that this correlated with poor prognosis. 23 These data indicate that EBV-driven LMP-1 activation could upregulate PD-L1 in EBV-positive PCNSLs, and we have previously reported that LMP-1 gene deletion and EBVnuclear antigen 2 (EBNA-2) expression are important tumorigenic factors for EBV-positive PCNSL in immunocompetent elderly patients. 24 In the present study, we found no statistical difference in the number of PD-L1 TILs between EBV-positive and EBV-negative PCNSL samples.…”

Rediscovery of NF‐κB signaling in nasopharyngeal carcinoma: How genetic defects of NF‐κB pathway interplay with EBV in driving oncogenesis?

“…Induction of PD‐L1 in melanoma cells is dependent on activation of NF‐κB (Gowrishankar et al, ). It has been demonstrated that NF‐κB activation contribute to LMP‐1 mediated induction of PD‐L1 in NPC cells and natural killer/T‐cell lymphoma (Bi et al, ; Fang et al, ) (Figure ). However, the relationship between PD‐L1 expression and NPC clinical outcomes is remain controversial (Li, Ding, et al, ; Zhu et al, ).…”

Epstein-Barr Virus LMP1-Mediated Oncogenicity

“…An adenoviral vector-based vaccine has shown promise for targeting LMP2A, EBNA1, and, when expressed, LMP1 in nasopharyngeal carcinoma (77)(78)(79). LMP1 drives the expression of the T-cell inhibitory receptor PD-L1 (80)(81)(82), and PD-1-PD-L1 immune checkpoint blockade has improved EBV ϩ lymphoma and NPC treatment responses (19,(83)(84)(85). It will be of interest to determine whether checkpoint-blockade, perhaps together with strategies to induce EBV lytic gene expression, synergizes with adoptive immunotherapy approaches.…”