Exploiting tumour cell dependency on pro-survival BCL2 proteins with BH3 mimetics

The RAS-RAF-MEK1/2-ERK1/2 signalling pathway is one of the most frequently deregulated pathways in human cancer, with mutations in KRAS and BRAF commonly occurring in cancers of the pancreas, skin, and colon, among others. Indeed, BRAF and MEK1/2 inhibitors are approved for the treatment of BRAF-mutant malignant melanoma and are improving patient outcomes. However, the development of acquired resistance to these agents is inevitable, highlighting the need for strategies to enhance their primary efficacy in the clinic. Inhibition of ERK1/2 signalling increases the abundance of pro-apoptotic BH3-only proteins such as BIM and BMF. However, despite this, responses to ERK1/2 pathway inhibitors are typically cytostatic, reflecting the residual activity of pro-survival BCL2 proteins. In this thesis, we determined that melanoma cells had a high MCL1:BCL-XL ratio, and as a result were biased towards MCL1 due to low expression of BCL-XL. Consequently, melanoma cells were uniquely dependent on MCL1 to restrain the pro-apoptotic BH3-only proteins induced by ERK1/2 pathway inhibition. The BH3 mimetic AZD5991, a selective MCL1 inhibitor, combined with ERK1/2 pathway inhibitors to drive striking synergistic apoptosis in vitro and robust tumour regressions in vivo. CRISPR/Cas9 gene editing of BIM and BMF in two melanoma cell lines showed that the cell death was substantially BIM/BMF-dependent, and required BAK and BAX to execute. In contrast to melanoma, colorectal cancer (CRC) cells exhibit increased expression of BCL-XL, with a low MCL1:BCL-XL ratio. The combination of MEK1/2 inhibitors with pan-BH3 mimetics that target BCL2, BCL-w and BCL-XL (such as ABT-263) has previously been explored in CRC cells. However, results in this thesis demonstrated that BCL-XL was the critical pro-survival protein in CRC cells responsible for buffering the pro-apoptotic effects of ERK1/2 pathway inhibition. CRC cell lines were completely refractory to BCL2 inhibition when combined with the MEK1/2 inhibitor selumetinib. MEK1/2 inhibitors primed CRC cells for rapid BAX-dependent apoptosis upon BCL-XL antagonism. BH3 mimetics combined with the ERK1/2 inhibitors SCH772984 or AZ6197 in a model of acquired resistance to BRAF and/or MEK1/2 inhibitors in A375 melanoma cells to drive striking apoptosis in vitro and in vivo. Combined BRAF and MCL1 inhibition delayed the onset of acquired resistance to BRAF inhibitor monotherapy in melanoma cells. In SW620 (CRC) cells, combined MEK1/2 and BCL-XL inhibition caused substantial cell death and did not result in the outgrowth of resistant clones; this combination possibly induced senescence in the residual “persister” cells. Finally, in addition to apoptosis, an alternate temporally-distinct cell death modality occurred in CRC cells treated with combined MEK1/2 and BCL-XL inhibition, and this was amplified when caspases were inhibited. This caspase-independent cell death was subsequently determined to be RIPK1-dependent necroptosis, which was reversed by inhibition of RIPK1 by necrostatin-1. BCL-XL may directly inhibit necroptosis induction at the level of the necrosome through the binding of the effector protein MLKL, which was displaced upon BCL-XL inhibition. BH3 mimetics are effective as single agents for the treatment of haematological malignancies, but their application in solid tumours needs to be refined. The results presented here demonstrate that BH3 mimetics harness the apoptotic potential of ERK1/2 pathway inhibitors to drive striking, synergistic cell death in melanoma and CRC cells. The ratio of pro-survival proteins could represent a potential clinical biomarker, and be informative in the clinic to drive BH3 mimetic combination choices.Cambridge International Trust scholarship AstraZenec

NuBrain: UK consortium for optimal nutrition for healthy brain ageing

With an ageing global population, there is an urgent need to identify effective strategies to maintain brain health across the life course and therein minimise the risk of age‐related neurodegenerative disorders reaching a severe stage which may manifest as dementia. An increasing body of evidence indicates that nutrition is a modifiable lifestyle factor that can promote healthy brain ageing and reduce dementia risk. However, at present, little is known about which dietary patterns, foods and food bioactives influence brain function during ageing, and more research is required to identify at‐risk individuals and population subgroups who are most likely to benefit from future nutritional intervention intended to promote healthier brain ageing. This article introduces the newly established Medical Research Council‐funded NuBrain consortium, the vision of which is to provide a step change in research in the area by developing novel approaches and techniques to further understand the complex interactions between diet and brain health and how we can support appropriate behaviour changes in the population. NuBrain will form a new, sustainable and internationally field‐leading research consortium with multidisciplinary and complementary areas of expertise to address the fundamental research challenges in this area

Health behaviour change during the UK COVID-19 lockdown: findings from the first wave of the C-19 health behaviour and wellbeing daily tracker study

Objectives: To provide baseline cohort descriptives and assess change in health behaviours since the UK COVID-19 lockdown. Design: A prospective cohort (N=1,044) of people recruited online, purposively targeting vulnerable populations. Methods: After a baseline survey (April 2020), participants completed 3 months of daily ecological momentary assessments (EMA). Dietary, physical activity, alcohol, smoking, vaping and substance use behaviours collected retrospectively for the pre-COVID-19 period were compared with daily EMA surveys over the first 30 days during early lockdown. Predictors of behaviour change were assessed using multivariable regression models. Results: 30% of the cohort had a COVID-19 at risk health condition, 37% were classed as deprived and 6% self-reported a mental health condition. Relative to pre-pandemic levels, participants ate almost one portion of fruit and vegetables less per day (vegetables mean difference -0.33, 95% CI -0.40, -0.25; fruit -0.57, 95% CI -0.64, -0.50), but showed no change in high sugar portions per day (-0.03, 95% CI -0.12, 0.06). Participants spent half a day less per week doing ≥30 minutes of moderate to vigorous physical activity (-0.57, 95% CI -0.73, -0.40) but slightly increased days of strength training (0.21, 95% CI 0.09, 0.34), increased alcohol intake (AUDIT-C score change 0.25, 95% CI 0.13, 0.37), though did not change smoking, vaping or substance use behaviour. Worsening health behaviour change was associated with being younger, female and higher body mass index. Conclusions: The cohort reported worsening health behaviours during early lockdown. Longer term changes will be investigated using further waves of data collection

Adherence to the Eatwell Guide and cardiometabolic, cognitive and neuroimaging parameters: An analysis from the PREVENT dementia study

Background: The Eatwell guide reflects the UK government’s recommendations for a healthy and balanced diet. Previous research has identified associations between healthy eating patterns and both cardiovascular and brain health, although there is little evidence specifically focusing on the Eatwell Guide. To date no research has investigated associations between the Eatwell Guide and risk for future dementia. Methods: Data from the PREVENT dementia cohort study baseline visit was used in this analysis. Binary and graded Eatwell Guide scores (BEWG, GEWG) were created from a self-reported Food Frequency Questionnaire. The CAIDE score was included as the primary outcome measure to represent risk for future Alzheimer’s disease. Secondary outcome measures included cardiometabolic health measures and brain health measures. Generalised additive models were run in R. Results: A total of 517 participants were included in the analysis, with a mean BEWG score of 4.39 (±1.66) (out of a possible 12 points) and GEWG score of 39.88 (±6.19) (out of a possible 60 points). There was no significant association between either Eatwell Guide score and the CAIDE score (BEWG β: 0.07, 95% confidence interval (CI): -0.07, 0.22; GEWG β: 0.02, 95% CI: -0.02, 0.06) or any measures of brain health. There was a significant association between higher GEWG score and lower systolic and diastolic blood pressure and body mass index (BMI) (systolic β: -0.24, 95% CI: -0.45, -0.03; diastolic β: -0.16, 95% CI: -0.29, -0.03; BMI β: -0.09, 95% CI: -0.16, -0.01). Conclusions: Although not directly associated with the CAIDE score, the Eatwell Guide dietary pattern may be beneficial for dementia prevention efforts through the modification of hypertension and obesity, which are both known risk factors for dementia. Future work could replicate these findings in other UK-based cohorts as well as further development of Eatwell Guide scoring methodologies

Targeting melanoma’s MCL1 bias unleashes the apoptotic potential of BRAF and ERK1/2 pathway inhibitors

Funder: AstraZenecaAbstract: BRAF and MEK1/2 inhibitors are effective in melanoma but resistance inevitably develops. Despite increasing the abundance of pro-apoptotic BIM and BMF, ERK1/2 pathway inhibition is predominantly cytostatic, reflecting residual pro-survival BCL2 family activity. Here, we show that uniquely low BCL-XL expression in melanoma biases the pro-survival pool towards MCL1. Consequently, BRAF or MEK1/2 inhibitors are synthetic lethal with the MCL1 inhibitor AZD5991, driving profound tumour cell death that requires BAK/BAX, BIM and BMF, and inhibiting tumour growth in vivo. Combination of ERK1/2 pathway inhibitors with BCL2/BCL-w/BCL-XL inhibitors is stronger in CRC, correlating with a low MCL1:BCL-XL ratio; indeed the MCL1:BCL-XL ratio is predictive of ERK1/2 pathway inhibitor synergy with MCL1 or BCL2/BCL-w/BCL-XL inhibitors. Finally, AZD5991 delays acquired BRAFi/MEKi resistance and enhances the efficacy of an ERK1/2 inhibitor in a model of acquired BRAFi + MEKi resistance. Thus combining ERK1/2 pathway inhibitors with MCL1 antagonists in melanoma could improve therapeutic index and patient outcomes

C-19 Wellbeing Tracker study

COVID-19 wellbeing and health behaviour daily tracking study, using Nof1 design to monitor changes in health behaviour in the UK during social distancing measures as a result of COVID-19 pandemi

Identifying indirect impacts of the COVID pandemic: The C-19 health behaviour and wellbeing daily tracker study

Study summaryIn rapid response to the COVID-19 pandemic and the sweeping changes to healthcare and restrictions on daily living, we set up a mixed methods UK intensive longitudinal study to understand the impact on health behaviours and mental health/wellbeing.</div

Effectiveness of lifestyle and psychosocial interventions in reducing cognitive decline in older people: Systematic review

BackgroundObservational findings suggest that a third of dementia cases are attributable to modifiable risk factors (Livingston et al, 2017). However, we are still unclear on what non- pharmacological interventions should look like or what a manualised dementia prevention programme might include.MethodPubMed, EMBASE (Ovid), PsycINFO, CINAHL, Web of Science, and reference lists of included studies were systematically searched and screened by two independent reviewers. We included lifestyle and psychosocial interventions that aimed to reduce cognitive decline in healthy people aged 50+, and people of any age with Subjective Cognitive Decline or Mild Cognitive Impairment. We narratively synthesised evidence, prioritising results from studies rated at lower Risk of Bias (ROB) and used Centre for Evidence Based Medicine guidelines to grade levels of evidence. These findings were used to inform co- production of an internationally collaborated APPLE- Tree (Active Prevention in People at risk of dementia: Lifestyle, bEhaviour change and Technology to REducE cognitive and functional decline) programme.ResultA total of 64 studies were included describing psychosocial (n=12), multi- domain (n=10), exercise (n=36) and dietary (n=6) interventions. We found Grade A evidence that 4+ months of aerobic exercise twice weekly had a moderate effect on global cognition. With interventions that integrate, cognitive and motor challenges (e.ge. dance or dumb bell training) had small to moderate effects on memory or global cognition. We also found Grade B evidence that 4+ months of creative art or storytelling groups; 6 months of resistance training and a two- year, dietary, exercise, cognitive training and social intervention had small but positive effect on global cognition. Conflicting evidence was observed for interventions solely focusing on increasing Mediterranean diet adherence. With effects for some interventions remaining up to a year beyond facilitated sessions. Only two lower ROB studies measured impact of non- pharmacological interventions onto dementia incidence with neither finding significant effects.ConclusionBased on current published findings an evidence- based intervention strategy to improve global cognition, memory and executive functioning should include group therapy carried out for 4+ months, promoting engagement in regular (at least weekly) activity, involving aerobic or resistance exercise, and cognitively demanding (visuospatial/memory) or creative tasks.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163848/1/alz042843.pd

Mediterranean diet adherence is associated with lower dementia risk, independent of genetic predisposition: findings from the UK Biobank prospective cohort study

BACKGROUND: The identification of effective dementia prevention strategies is a major public health priority, due to the enormous and growing societal cost of this condition. Consumption of a Mediterranean diet (MedDiet) has been proposed to reduce dementia risk. However, current evidence is inconclusive and is typically derived from small cohorts with limited dementia cases. Additionally, few studies have explored the interaction between diet and genetic risk of dementia. METHODS: We used Cox proportional hazard regression models to explore the associations between MedDiet adherence, defined using two different scores (MedDiet Adherence Screener [MEDAS] continuous and Mediterranean diet Pyramid [PYRAMID] scores), and incident all-cause dementia risk in 60298 participants from UK Biobank, followed for an average 9.1 years. The interaction between diet and polygenic risk for dementia was also tested. RESULTS: Higher MedDiet adherence was associated with lower dementia risk (MEDAS continuous: HR=0.77, 95% CI=0.65-0.91; PYRAMID: HR=0.86, 95% CI=0.73-1.02 for highest versus lowest tertiles). There was no significant interaction between MedDiet adherence defined by the MEDAS continuous and PYRAMID scores and polygenic risk for dementia. CONCLUSIONS: Higher adherence to a MedDiet was associated with lower dementia risk, independent of genetic risk, underlining the importance of diet in dementia prevention interventions