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Epstein-Barr virus-encoded EBNA2 alters immune checkpoint PD-L1 expression by downregulating miR-34a in B-cell lymphomas.

Eleni AnastasiadouDina StroopinskyStella AlimpertiAlan L JiaoAthalia R PyzerClaudia CippitelliGiuseppina PepeMartina SeveraJacalyn RosenblattMarilena P EtnaSimone RiegerBettina KempkesEliana M CocciaShannan J Ho SuiChristopher S ChenStefania UcciniDavid AviganAlberto FaggioniPankaj TrivediFrank J Slack
Published in: Leukemia (2018)
Cancer cells subvert host immune surveillance by altering immune checkpoint (IC) proteins. Some Epstein-Barr virus (EBV)-associated tumors have higher Programmed Cell Death Ligand, PD-L1 expression. However, it is not known how EBV alters ICs in the context of its preferred host, the B lymphocyte and in derived lymphomas. Here, we found that latency III-expressing Burkitt lymphoma (BL), diffuse large B-cell lymphomas (DLBCL) or their EBNA2-transfected derivatives express high PD-L1. In a DLBCL model, EBNA2 but not LMP1 is sufficient to induce PD-L1. Latency III-expressing DLBCL biopsies showed high levels of PD-L1. The PD-L1 targeting oncosuppressor microRNA miR-34a was downregulated in EBNA2-transfected lymphoma cells. We identified early B-cell factor 1 (EBF1) as a repressor of miR-34a transcription. Short hairpin RNA (shRNA)-mediated knockdown of EBF1 was sufficient to induce miR-34a transcription, which in turn reduced PD-L1. MiR-34a reconstitution in EBNA2-transfected DLBCL reduced PD-L1 expression and increased its immunogenicity in mixed lymphocyte reactions (MLR) and in three-dimensional biomimetic microfluidic chips. Given the importance of PD-L1 inhibition in immunotherapy and miR-34a dysregulation in cancers, our findings may have important implications for combinatorial immunotherapy, which include IC inhibiting antibodies and miR-34a, for EBV-associated cancers.
Keyphrases
  • epstein barr virus
  • diffuse large b cell lymphoma
  • cell proliferation
  • long non coding rna
  • long noncoding rna
  • public health
  • drug delivery
  • peripheral blood
  • sensitive detection
  • cancer therapy
  • single molecule