Distinct NF-kB Regulation Favors a Synergic Action of Pevonedistat and Laduviglusib in B-Chronic Lymphocytic Leukemia Cells Ex Vivo.

Background/

Objectives

Chronic lymphocytic leukemia (CLL) remains an incurable B-cell malignancy. B-CLL cells exhibit an extended lifespan in part due to the activation of survival pathways such as NF-kB. A crosstalk between NF-kB and GSK-3β pathways has been reported. NF-kB has also been identified as a primary target of the NEDD8-activating enzyme inhibitor MLN4924. Our objective was to investigate potential synergies of MLN4924 with other NF-kB-targeting agents for the treatment of CLL and elucidate the mechanisms of action underlying this pathway regulation.

Methods

To assess the cytotoxic efficacy of the combined ex vivo treatment with CHIR-99021 and MLN4924, we employed 7-AAD staining and XTT viability assays on primary samples from CLL patients. Subsequently, we conducted various analyses to identify the molecular mechanisms underlying the cytotoxic effects of this combination.

Results

We discovered a discrepancy between the mRNA and protein levels of IkBɑ and provided evidence of translational control over its expression. This observation may explain why, unlike other cell types, B-CLL cells did not activate NF-kB signaling following inhibition of GSK-3ß. Furthermore, we describe a synergistic effect between a specific GSK-3ß inhibitor, CHIR-99021/Laduviglusib, and the NEDD8-activating enzyme inhibitor MLN4924/Pevonedistat, at doses that only slightly affect healthy B cell viability ex vivo. We investigated the molecular basis of this co-induction of cell death by analyzing the alterations in apoptosis-related gene expression. We found that the combinational treatment enhances a reduction in BCL2 mRNA expression levels, providing an alternative approach for BCL-2 inhibition in CLL that could have therapeutic implications for the treatment of refractory CLL cases.

Conclusions

our findings revealed a unique interaction between GSK-3ß and NF-kB pathways in CLL and their regulation of BCL2 expression.