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Up-regulation of the PI3K/AKT and RHO/RAC/PAK signalling pathways in CHK1 inhibitor resistant Eµ-Myc lymphoma cells

Lookup NU author(s): Dr Jill Hunter, Scott Kerridge, Dr Nicola Hannaway, Dr Saimir Luli, Dr Iglika Ivanova, Dr Jonathan Coxhead, Leigh Taylor, Dr Peter Leary, Dr Megan Hasoon, Professor Neil PerkinsORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2022 The Author(s). The development of resistance and the activation of bypass pathway signalling represents a major problem for the clinical application of protein kinase inhibitors. While investigating the effect of either a c-Rel deletion or RelAT505A phosphosite knockin on the Eµ-Myc mouse model of B-cell lymphoma, we discovered that both NF-κB subunit mutations resulted in CHK1 inhibitor resistance, arising from either loss or alteration of CHK1 activity, respectively. However, since Eµ-Myc lymphomas depend on CHK1 activity to cope with high levels of DNA replication stress and consequent genomic instability, it was not clear how these mutant NF-κB subunit lymphomas were able to survive. To understand these survival mechanisms and to identify potential compensatory bypass signalling pathways in these lymphomas, we applied a multi-omics strategy. With c-Rel-/- Eµ-Myc lymphomas we observed high levels of Phosphatidyl-inositol 3-kinase (PI3K) and AKT pathway activation. Moreover, treatment with the PI3K inhibitor Pictilisib (GDC-0941) selectively inhibited the growth of reimplanted c-Rel-/- and RelAT505A, but not wild type (WT) Eµ-Myc lymphomas. We also observed up-regulation of a RHO/RAC pathway gene expression signature in both Eµ-Myc NF-κB subunit mutation models. Further investigation demonstrated activation of the RHO/RAC effector p21-activated kinase (PAK) 2. Here, the PAK inhibitor, PF-3758309 successfully overcame resistance of RelAT505A but not WT lymphomas. These findings demonstrate that up-regulation of multiple bypass pathways occurs in CHK1 inhibitor resistant Eµ-Myc lymphomas. Consequently, drugs targeting these pathways could potentially be used as either second line or combinatorial therapies to aid the successful clinical application of CHK1 inhibitors.

Publication metadata

Author(s): Hunter JE, Campbell AE, Kerridge S, Fraser C, Hannaway NL, Luli S, Ivanova I, Brownridge PJ, Coxhead J, Taylor L, Leary P, Hasoon MSR, Eyers CE, Perkins ND

Publication type: Article

Publication status: Published

Journal: Biochemical Journal

Year: 2022

Volume: 479

Issue: 19

Pages: 2131-2151

Online publication date: 14/10/2022

Acceptance date: 20/09/2022

Date deposited: 02/11/2022

ISSN (print): 0264-6021

ISSN (electronic): 1470-8728

Publisher: Portland Press


DOI: 10.1042/BCJ20220103

PubMed id: 36240067


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Funder referenceFunder name
11022Bloodwise (Formerly Leukaemia and Lymphoma Research)
C1443/A12750Cancer Research UK CRUK (open competition)
C1443/A22095Cancer Research UK CRUK (open competition)