Targeting the Non-Canonical NF-κB Pathway in Chronic Lymphocytic Leukemia and Multiple Myeloma

Abstract

In this study, we evaluated an NF-κB inducing kinase (NIK) inhibitor, CW15337, in primary chronic lymphocytic leukemia (CLL) cells, CLL and multiple myeloma (MM) cell lines and normal B- and T-lymphocytes. Basal NF-κB subunit activity was characterized using an enzyme linked immunosorbent assay (ELISA), and the effects of NIK inhibition were then assessed in terms of cytotoxicity and the expression of nuclear NF-κB subunits following monoculture and co-culture with CD40L-expressing fibroblasts, as a model of the lymphoid niche. CW15337 induced a dose-dependent increase in apoptosis, and nuclear expression of the non-canonical NF-κB subunit, p52, was correlated with sensitivity to CW15337 (p = 0.01; r2 = 0.39). Co-culture on CD40L-expressing cells induced both canonical and non-canonical subunit expression in nuclear extracts, which promoted in vitro resistance against fludarabine and ABT-199 (venetoclax) but not CW15337. Furthermore, the combination of CW15337 with fludarabine or ABT-199 showed cytotoxic synergy. Mechanistically, CW15337 caused the selective inhibition of non-canonical NF-κB subunits and the transcriptional repression of BCL2L1, BCL2A1 and MCL1 gene transcription. Taken together, these data suggest that the NIK inhibitor, CW15337, exerts its effects via suppression of the non-canonical NF-κB signaling pathway, which reverses BCL2 family-mediated resistance in the context of CD40L stimulation.

B cell receptor signaling and associated pathways in the pathogenesis of chronic lymphocytic leukemia

“…Hence, targeting NF-κB signaling represents a potential future therapeutic approach to overcome CLL resistance which is supported by NF-κB survival signaling originating from the protective tumor microenvironment. A first in vitro study shows promising effects in targeting the NF-κB inducing kinase (NIK) by the inhibitor CW15337 in CLL cell clones ( 180 ).…”

NF-kB and the CLL microenvironment

“…CD4+ T cells increase STAT6 driven BCR signaling through release of IL4 ( 56 ) and in normal B cells, this has been shown to be via activation of the non-canonical NF-κB pathway ( 57 ). CD4+ T cell activation of the non-canonical NF-κB pathway in CLL is also through CD40L activation of CD40 ( 58 , 59 ) and, as a result, CD40L and IL4 are important components of laboratory-based co-culture systems which aim to mimic the tumor microenvironment ( 40 , 60 , 61 ).…”

“…In addition to contributing to CLL cell survival, CD40L has been implicated in drug resistance in CLL, with microenvironmental agonists including CD40L inducing NF-κB mediated resistance to Venetoclax and ibrutinib ( 88 , 112 , 113 ). Interestingly, direct inhibition of NIK in vitro overcomes the protection offered by the CD40/CD40L interaction and induces CLL cell apoptosis in previously resistant cells ( 59 ). Targeting CD40/CD40L signaling has also been investigated in the context of CLL, with monoclonal antibody to CD40 Selicrelumab showing promising results through the sensitization of CD20 monoclonal antibodies such as Rituximab and Obinutuzumab ( 114 , 115 ).…”

PYK2 is overexpressed in chronic lymphocytic leukaemia: A potential new therapeutic target

“…In a genome‐wide study, PYK2 has been found to correlate with improved outcomes in CLL patients under chemoimmunotherapy regimen 12 . More recently FAK has been proposed as a modulator of migration and invasion in CLL 13 …”

“…12 More recently FAK has been proposed as a modulator of migration and invasion in CLL. 13 In a pre-clinical setting, it has been previously demonstrated that targeting FAK and/or PYK2 could bring some benefits in some haematological cancers such as Multiple Myeloma, 14 Myelodysplastic Syndromes, 15 Acute Myeloid Leukaemia, 16 BCR/ ABL-transformed model of Chronic Myeloid Leukaemia 17 and in Mantle Cell Lymphoma (MCL). In particular, it has been demonstrated that MCL cells, upon culture with stromal cells, show an activation of pathways such as NF-kB, Akt, c-Myc, Cyclin-D and p42/44, all associated with cancer progression, and FAK inhibition abrogates the activation of all these effectors.…”