Factors involved in CLL pathogenesis and cell survival are disrupted by differentiation of CLL B-cells into antibody-secreting cells.

Hussein Ghamlouch,Bruno Royer,Brigitte Gubler,Stéphanie Trudel,Jean-Pierre Marolleau,Amrathlal Rabbind Singh,Sébastien Dupont,Hakim Ouled-Haddou,Walaa Darwiche,Ahmed Hodroge,Caroline Guignant

doi:10.18632/oncotarget.3941

Abstract

Recent research has shown that chronic lymphocytic leukemia (CLL) B-cells display a strong tendency to differentiate into antibody-secreting cells (ASCs) and thus may be amenable to differentiation therapy. However, the effect of this differentiation on factors associated with CLL pathogenesis has not been reported. In the present study, purified CLL B-cells were stimulated to differentiate into ASCs by phorbol myristate acetate or CpG oligodeoxynucleotide, in combination with CD40 ligand and cytokines in a two-step, seven-day culture system. We investigated (i) changes in the immunophenotypic, molecular, functional, morphological features associated with terminal differentiation into ASCs, (ii) the expression of factors involved in CLL pathogenesis, and (iii) the expression of pro- and anti-apoptotic proteins in the differentiated cells. Our results show that differentiated CLL B-cells are able to display the transcriptional program of ASCs. Differentiation leads to depletion of the malignant program and deregulation of the apoptosis/survival balance. Analysis of apoptosis and the cell cycle showed that differentiation is associated with low cell viability and a low rate of cell cycle entry. Our findings shed new light on the potential for differentiation therapy as a part of treatment strategies for CLL.

Highlights

Chronic lymphocytic leukemia (CLL) is a hetero geneous disease characterized by clonal proliferation and the accumulation of mature CD5+ B-cells in lymphoid tissues, bone marrow, and peripheral blood
Recent research has shown that chronic lymphocytic leukemia (CLL) B-cells display a strong tendency to differentiate into antibody-secreting cells (ASCs) and may be amenable to differentiation therapy
We investigated the effect of CLL B-cell differentiation in phorbol myristate acetate (PMA)/CD40L/c system on the expression of factors associated with CLL pathogenesis, including LEF1, TCL1, ROR1, FMOD, TNFRSF13B/TACI, BIRC5/ survivin [55], p27, PI3K and BTK

Summary

INTRODUCTION

Chronic lymphocytic leukemia (CLL) is a hetero geneous disease characterized by clonal proliferation and the accumulation of mature CD5+ B-cells in lymphoid tissues, bone marrow, and peripheral blood. Targeting BCR signaling pathways by siRNA molecules or kinases inhibitors in vitro induces downregulation of anti-apoptotic protein myeloid cell leukemia 1 (MCL1) and CLL B-cells apoptosis [26,27,28] All these molecules are involved in the pathogenesis of CLL and constitute a part of the malignant program of CLL B-cells [5,6,7,8,9,10]. Using a similar culture systems, in this study we sought to investigate the impact of B-cell differentiation on the expression of factors that contribute to the physiopathology of CLL and/or are known to be deregulated in CLL B-cells (including LEF1, TCL1, ROR1, FMOD, TACI, PI3K, BTK and p27). We investigated changes in the expression of pro- and anti-apoptotic proteins in ASCs, including MCL1, p53-upregulated modulator of apoptosis (PUMA), X-linked inhibitor of apoptosis protein (XIAP), B-cell lymphoma 2 (BCL2) and B-cell lymphomaextra-large (BCLxL)

RESULTS

DISCUSSION

Findings

MATERIALS AND METHODS