Life Sciences Research for Lifelong Health

Simon Cook

Research Summary

One of the keys to understanding lifelong health is to understand the signalling pathways that operate inside cells and govern key fate decisions such as cell death, cell survival, cell division or cell senescence (collectively cell longevity).  These signalling pathways involve enzymes called ‘protein kinases’ that attach phosphate groups to specific cellular proteins, thereby controlling their activity, location or abundance. In this way protein kinases orchestrate the cellular response to growth factors, nutrient availability or stress and damage.

Ageing results in part from the imbalance between cellular damage, accrued throughout life, and the progressive decline in stress response and repair pathways. We are interested in how protein kinases function in stress responses, the removal of damaged cellular components (e.g. autophagy, see also Nicholas Ktistakis and Oliver Florey) and the control of cellular lifespan. We believe this will enhance our understanding of how the normal declines in these processes drive ageing.

Signalling pathways are frequently de-regulated in certain age-related diseases – notably in cancer, inflammation and neurodegeneration – and many protein kinases are attractive drug targets. Consequently we translate our basic knowledge of signalling through collaborations with charities and pharmaceutical companies (e.g. AstraZeneca and MISSION Therapeutics).

Latest Publications

MEK1/2 inhibitor withdrawal reverses acquired resistance driven by BRAF amplification whereas KRAS amplification promotes EMT-chemoresistance.
Sale MJ, Balmanno K, Saxena J, Ozono E, Wojdyla K, McIntyre RE, Gilley R, Woroniuk A, Howarth KD, Hughes G, Dry JR, Arends MJ, Caro P, Oxley D, Ashton S, Adams DJ, Saez-Rodriguez J, Smith PD, Cook SJ

Acquired resistance to MEK1/2 inhibitors (MEKi) arises through amplification of BRAF or KRAS to reinstate ERK1/2 signalling. Here we show that BRAF amplification and MEKi resistance are reversible following drug withdrawal. Cells with BRAF amplification are addicted to MEKi to maintain a precise level of ERK1/2 signalling that is optimal for cell proliferation and survival, and tumour growth in vivo. Robust ERK1/2 activation following MEKi withdrawal drives a p57-dependent G1 cell cycle arrest and senescence or expression of NOXA and cell death, selecting against those cells with amplified BRAF. p57 expression is required for loss of BRAF amplification and reversal of MEKi resistance. Thus, BRAF amplification confers a selective disadvantage during drug withdrawal, validating intermittent dosing to forestall resistance. In contrast, resistance driven by KRAS amplification is not reversible; rather ERK1/2 hyperactivation drives ZEB1-dependent epithelial-to-mesenchymal transition and chemoresistance, arguing strongly against the use of drug holidays in cases of KRAS amplification.

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Nature communications, 10, 2041-1723, 2030, 2019

PMID: 31048689

Over-expressed, N-terminally truncated BRAF is detected in the nucleus of cells with nuclear phosphorylated MEK and ERK.
Hey F, Andreadi C, Noble C, Patel B, Jin H, Kamata T, Straatman K, Luo J, Balmanno K, Jones DTW, Collins VP, Cook SJ, Caunt CJ, Pritchard C

BRAF is a cytoplasmic protein kinase, which activates the MEK-ERK signalling pathway. Deregulation of the pathway is associated with the presence of mutations in human cancer, the most common being , although structural rearrangements, which remove N-terminal regulatory sequences, have also been reported. RAF-MEK-ERK signalling is normally thought to occur in the cytoplasm of the cell. However, in an investigation of BRAF localisation using fluorescence microscopy combined with subcellular fractionation of Green Fluorescent Protein (GFP)-tagged proteins expressed in NIH3T3 cells, surprisingly, we detected N-terminally truncated BRAF (ΔBRAF) in both nuclear and cytoplasmic compartments. In contrast, ΔCRAF and full-length, wild-type BRAF (BRAF) were detected at lower levels in the nucleus while full-length BRAF was virtually excluded from this compartment. Similar results were obtained using ΔBRAF tagged with the hormone-binding domain of the oestrogen receptor (hbER) and with the KIAA1549-ΔBRAF translocation mutant found in human pilocytic astrocytomas. Here we show that GFP-ΔBRAF nuclear translocation does not involve a canonical Nuclear Localisation Signal (NLS), but is suppressed by N-terminal sequences. Nuclear GFP-ΔBRAF retains MEK/ERK activating potential and is associated with the accumulation of phosphorylated MEK and ERK in the nucleus. In contrast, full-length GFP-BRAF and GFP-BRAF are associated with the accumulation of phosphorylated ERK but not phosphorylated MEK in the nucleus. These data have implications for cancers bearing single nucleotide variants or N-terminal deleted structural variants of .

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Heliyon, 4, 2405-8440, e01065, 2018

PMID: 30603699

Targeting IKKβ in Cancer: Challenges and Opportunities for the Therapeutic Utilisation of IKKβ Inhibitors.
Prescott JA, Cook SJ

Deregulated NF-κB signalling is implicated in the pathogenesis of numerous human inflammatory disorders and malignancies. Consequently, the NF-κB pathway has attracted attention as an attractive therapeutic target for drug discovery. As the primary, druggable mediator of canonical NF-κB signalling the IKKβ protein kinase has been the historical focus of drug development pipelines. Thousands of compounds with activity against IKKβ have been characterised, with many demonstrating promising efficacy in pre-clinical models of cancer and inflammatory disease. However, severe on-target toxicities and other safety concerns associated with systemic IKKβ inhibition have thus far prevented the clinical approval of any IKKβ inhibitors. This review will discuss the potential reasons for the lack of clinical success of IKKβ inhibitors to date, the challenges associated with their therapeutic use, realistic opportunities for their future utilisation, and the alternative strategies to inhibit NF-κB signalling that may overcome some of the limitations associated with IKKβ inhibition.

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Cells, 7, 2073-4409, , 2018

PMID: 30142927

Group Members

Latest Publications

Visualisation of Endogenous ERK1/2 in Cells with a Bioorthogonal Covalent Probe.

Sipthorp J, Lebraud H, Gilley R

Bioconjugate chemistry
1520-4812: (2017)

PMID: 28449575

RNA-binding proteins ZFP36L1 and ZFP36L2 promote cell quiescence.

Galloway A, Saveliev A, Łukasiak S

Science (New York, N.Y.)
352 1095-9203:453-9 (2016)

PMID: 27102483

Tumor cells with KRAS or BRAF mutations or ERK5/MAPK7 amplification are not addicted to ERK5 activity for cell proliferation.

Lochhead PA, Clark J, Wang LZ

Cell cycle (Georgetown, Tex.)
15 1551-4005:506-18 (2016)

PMID: 26959608

Maternal DNA Methylation Regulates Early Trophoblast Development.

Branco MR, King M, Perez-Garcia V

Developmental cell
36 1878-1551:152-63 (2016)

PMID: 26812015