IL-21 Stimulates the expression and activation of cell cycle regulators and promotes cell proliferation in EBV-positive diffuse large B cell lymphoma

Yuxuan Wang,Xiyunyi Cai,Wei Xu,Yingying Zhang,Xueting Cui,Hao Dong,Yuanyuan Hao,Weijia Xie,Harvest F Gu ,Lei Fan,Jianyong Li,Lei Cai,Feng Ge,Jiamin Chen,Chang Mou,Yue Tong,Chenjie Feng ,Yuming Wang ,Shu‐Lin Wu ,Liang Wu

doi:10.1038/s41598-020-69227-0

Abstract

The clinical features of EBV-positive diffuse large B cell lymphoma (DLBCL) indicate a poorer prognosis than EBV-negative DLBCL. Currently, there is no efficacious drug for EBV-positive DLBCL. The cytokine interleukin-21 (IL-21) has been reported to be pro-apoptotic in DLBCL cell lines and is being explored as a new therapeutic strategy for this type of lymphomas. However, our previous studies showed that IL-21 stimulation of EBV-positive DLBCL cell lines leads to increased proliferation. Here, analysis of a rare clinical sample of EBV-positive DLBCL, in combination with a NOD/SCID mouse xenograft model, confirmed the effect of IL-21 on the proliferation of EBV-positive DLBCL cells. Using RNA-sequencing, we identified the pattern of differentially-expressed genes following IL-21 treatment and verified the expression of key genes at the protein level using western blotting. We found that IL-21 upregulates expression of the host MYC and AP-1 (composed of related Jun and Fos family proteins) and STAT3 phosphorylation, as well as expression of the viral LMP-1 protein. These proteins are known to promote the G1/S phase transition to accelerate cell cycle progression. Furthermore, in NOD/SCID mouse xenograft model experiments, we found that IL-21 treatment increases glucose uptake and angiogenesis in EBV-positive DLBCL tumours. Although more samples are needed to validate these observations, our study reconfirms the adverse effects of IL-21 on EBV-positive DLBCL, which has implications for the drug development of DLBCL.

Highlights

The clinical features of Epstein-Barr virus (EBV)-positive diffuse large B cell lymphoma (DLBCL) indicate a poorer prognosis than EBV-negative DLBCL
Using RNA-seq analysis of EBV latency gene transcripts, we found that the EBV-positive DLBCL primary cells expressed the full set of EBV latency genes, which is similar to Farage cells (Fig. 1d)
By RNA-seq analysis using hierarchical clustering, we found that the direction of the regulation of differential expressed gene (DEG) in the primary cells and in Farage cells after IL-21 treatment was similar

Summary

Introduction

The clinical features of EBV-positive diffuse large B cell lymphoma (DLBCL) indicate a poorer prognosis than EBV-negative DLBCL. IL-21 induces LMP-1 expression, as well as activation of the host STAT3, in a type I latency Burkitt lymphoma cell line and in a conditional LCL9 This common gamma chain cytokine is an effective B cell activator and plasma cell differentiation inducer produced by CD4 + T cells[15]. We found that regulation of EBV latency gene expression by IL-21 in five DLBCL-derived cell lines is dependent on the type of EBV latency program (type I, II or III)[13] These observations might explain why while IL-21 has been found to promote apoptosis of DLBCL cell lines via STAT3 activation and c-Myc expression resulting in tumour regression and prolonged survival of m ice[16,17], IL-21 treatment of EBV-positive DLBCL cell lines results in increased cell p roliferation[18]. In combination with the observation that IL-21 has been used in a variety of clinical trials for the treatment of malignant tumours, it is necessary to further evaluate the pharmacological and physiological effects of IL-21 in the field of non-Hodgkin’s lymphoma (NHL) therapy

Objectives

Methods

Results

Conclusion