Biological rational for sequential targeting of Bruton tyrosine kinase and Bcl-2 to overcome CD40-induced ABT-199 resistance in mantle cell lymphoma.

Authors:

Chiron D, Dousset C, Brosseau C, Touzeau C, Maïga S, Moreau P, Pellat-Deceunynck C, Le Gouill S, Amiot M.

In:
Source: OncoTarget
Publication Date: (2015)
Issue: 6(11): 8750-9
Research Area:
Cancer Research/Cell Biology
Immunotherapy / Hematology
Cells used in publication:
Mino
Species: human
Tissue Origin: blood
JeKo-1
Species: human
Tissue Origin: blood
Z-138
Species: human
Tissue Origin: blood
Platform:
Nucleofector™ I/II/2b
4D-Nucleofector™ X-Unit
Experiment

Control non-targeted small interfering siRNA (si Ct) and siRNA against BCLXL and MCL1 were purchased from Thermo Scientific (Courtaboeuf, France). Z138 and
MINO cell lines were electroporated using a Nucleofector system (Amaxa, Lonza, Basel, Switzerland) according to the manufacturer’s instructions. Cells (5 × 105/ml) were suspended in Nucleofector solution T or SF and electroporated in the presence of 10 µmol/L siRNA (T01 for MINO, CM150 for Z138 and DN100 for JeKo-1).
The gene-silencing effect was evaluated by immunoblot analysis.

Abstract

The aggressive biological behavior of mantle cell lymphoma (MCL) and its short response to current treatment highlight a great need for better rational therapy. Herein, we investigate the ability of ABT-199, the Bcl-2-selective BH3 mimetic, to kill MCL cells. Among MCL cell lines tested (n = 8), only three were sensitive (LD50 < 200 nM). In contrast, all primary MCL samples tested (n = 11) were highly sensitive to ABT-199 (LD50 < 10 nM). Mcl-1 and Bcl-xL both confer resistance to ABT-199-specific killing and BCL2/(BCLXL+MCL1) mRNA ratio is a strong predictor of sensitivity. By mimicking the microenvironment through CD40 stimulation, we show that ABT-199 sensitivity is impaired through activation of NF-kB pathway and Bcl-x(L) up-regulation. We further demonstrate that resistance is rapidly lost when MCL cells detach from CD40L-expressing fibroblasts. It has been reported that ibrutinib induces lymphocytosis in vivo holding off malignant cells from their protective microenvironment. We show here for two patients undergoing ibrutinib therapy that mobilized MCL cells are highly sensitive to ABT-199. These results provide evidence that in situ ABT-199 resistance can be overcome when MCL cells escape from the lymph nodes. Altogether, our data support the clinical application of ABT-199 therapy both as a single agent and in sequential combination with BTK inhibitors.