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Regulation of Bcl-XL by non-canonical NF-κB in the context of CD40-induced drug resistance in CLL

Lookup NU author(s): Dr Elaine Willmore

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Abstract

© 2021, The Author(s).In chronic lymphocytic leukemia (CLL), the lymph node (LN) microenvironment delivers critical survival signals by inducing the expression of anti-apoptotic Bcl-2 members Bcl-XL, Bfl-1, and Mcl-1, resulting in apoptosis blockade. We determined previously that resistance against various drugs, among which is the clinically applied BH3 mimetic venetoclax, is dominated by upregulation of the anti-apoptotic regulator Bcl-XL. Direct clinical targeting of Bcl-XL by, e.g., Navitoclax is however not desirable due to induction of thrombocytopenia. Since the actual regulation of Bcl-XL in CLL in the context of the LN microenvironment is not well elucidated, we investigated various candidate LN signals to drive Bcl-XL expression. We found a dominance for NF-κB signaling upon CD40 stimulation, which results in activation of both the canonical and non-canonical NF-κB signaling pathways. We demonstrate that expression of Bcl-XL is first induced by the canonical NF-κB pathway, and subsequently boosted and continued via non-canonical NF-κB signaling through stabilization of NIK. NF-κB subunits p65 and p52 can both bind to the Bcl-XL promoter and activate transcription upon CD40 stimulation. Moreover, canonical NF-κB signaling was correlated with Bfl-1 expression, whereas Mcl-1 in contrast, was not transcriptionally regulated by NF-κB. Finally, we applied a novel compound targeting NIK to selectively inhibit the non-canonical NF-κB pathway and showed that venetoclax-resistant CLL cells were sensitized to venetoclax. In conclusion, protective signals from the CLL microenvironment can be tipped towards apoptosis sensitivity by interfering with non-canonical NF-κB signaling.


Publication metadata

Author(s): Haselager M, Thijssen R, West C, Young L, Van Kampen R, Willmore E, Mackay S, Kater A, Eldering E

Publication type: Article

Publication status: Published

Journal: Cell Death and Differentiation

Year: 2021

Pages: epub ahead of print

Online publication date: 25/01/2021

Acceptance date: 18/11/2020

ISSN (print): 1350-9047

ISSN (electronic): 1476-5403

Publisher: Springer Nature

URL: https://doi.org/10.1038/s41418-020-00692-w

DOI: 10.1038/s41418-020-00692-w


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