Amplification of MYCN is a driver mutation in a subset of human neuroendocrine tumors, including neuroblastoma. No small molecules that target N-Myc, the protein encoded by MYCN, are clinically ...available. N-Myc forms a complex with the Aurora-A kinase, which protects N-Myc from proteasomal degradation. Although stabilization of N-Myc does not require the catalytic activity of Aurora-A, we show here that two Aurora-A inhibitors, MLN8054 and MLN8237, disrupt the Aurora-A/N-Myc complex and promote degradation of N-Myc mediated by the Fbxw7 ubiquitin ligase. Disruption of the Aurora-A/N-Myc complex inhibits N-Myc-dependent transcription, correlating with tumor regression and prolonged survival in a mouse model of MYCN-driven neuroblastoma. We conclude that Aurora-A is an accessible target that makes destabilization of N-Myc a viable therapeutic strategy.
•Aurora-A-specific inhibitors disrupt the Aurora-A/N-Myc complex•Inhibitors trigger proteasomal degradation of N-Myc via Fbxw7 ubiquitin ligase•Inhibitors revert N-Myc-dependent gene expression in a mouse model of neuroblastoma•Inhibitors induce tumor regression and extend survival in this model
We undertook a comprehensive clinical and biological investigation of serial medulloblastoma biopsies obtained at diagnosis and relapse. Combined MYC family amplifications and P53 pathway defects ...commonly emerged at relapse, and all patients in this group died of rapidly progressive disease postrelapse. To study this interaction, we investigated a transgenic model of MYCN-driven medulloblastoma and found spontaneous development of Trp53 inactivating mutations. Abrogation of p53 function in this model produced aggressive tumors that mimicked characteristics of relapsed human tumors with combined P53-MYC dysfunction. Restoration of p53 activity and genetic and therapeutic suppression of MYCN all reduced tumor growth and prolonged survival. Our findings identify P53-MYC interactions at medulloblastoma relapse as biomarkers of clinically aggressive disease that may be targeted therapeutically.
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•Combined P53 and MYC family defects emerge at medulloblastoma relapse•P53-MYC defects are a biomarker for rapidly progressive relapsed disease•Trp53 and MYCN interact to drive aggressive medulloblastoma development in mice•Targeting MYCN or P53 pathway reactivation reduces tumor growth and prolongs survival
Hill et al. find that coincident MYC amplifications and p53 pathway defects are common in relapsed medulloblastoma (MB) and correlate with poor postrelapse prognosis. The authors go on to explore this MYC-p53 interaction in a mouse MB model and show that these tumors are dependent on both aberrations.
Hypoxia is known to be a poor prognostic indicator for nearly all solid tumours and also is predictive of treatment failure for radiotherapy, chemotherapy, surgery and targeted therapies. Imaging has ...potential to identify, spatially map and quantify tumour hypoxia prior to therapy, as well as track changes in hypoxia on treatment. At present no hypoxia imaging methods are available for routine clinical use. Research has largely focused on positron emission tomography (PET)-based techniques, but there is gathering evidence that MRI techniques may provide a practical and more readily translational alternative. In this review we focus on the potential for imaging hypoxia by measuring changes in longitudinal relaxation R
; termed oxygen-enhanced MRI or tumour oxygenation level dependent (TOLD) MRI and effective transverse relaxation R
*; termed blood oxygenation level dependent (BOLD) MRI, induced by inhalation of either 100% oxygen or the radiosensitising hyperoxic gas carbogen. We explain the scientific principles behind oxygen-enhanced MRI and BOLD and discuss significant studies and their limitations. All imaging biomarkers require rigorous validation in order to translate into clinical use and the steps required to further develop oxygen-enhanced MRI and BOLD MRI into decision-making tools are discussed.
Background
Comprehensive geriatric assessment (CGA) is a multi‐dimensional, multi‐disciplinary diagnostic and therapeutic process conducted to determine the medical, mental, and functional problems ...of older people with frailty so that a co‐ordinated and integrated plan for treatment and follow‐up can be developed. This is an update of a previously published Cochrane review.
Objectives
We sought to critically appraise and summarise current evidence on the effectiveness and resource use of CGA for older adults admitted to hospital, and to use these data to estimate its cost‐effectiveness.
Search methods
We searched CENTRAL, MEDLINE, Embase, three other databases, and two trials registers on 5 October 2016; we also checked reference lists and contacted study authors.
Selection criteria
We included randomised trials that compared inpatient CGA (delivered on geriatric wards or by mobile teams) versus usual care on a general medical ward or on a ward for older people, usually admitted to hospital for acute care or for inpatient rehabilitation after an acute admission.
Data collection and analysis
We followed standard methodological procedures expected by Cochrane and Effective Practice and Organisation of Care (EPOC). We used the GRADE approach to assess the certainty of evidence for the most important outcomes. For this update, we requested individual patient data (IPD) from trialists, and we conducted a survey of trialists to obtain details of delivery of CGA. We calculated risk ratios (RRs), mean differences (MDs), or standardised mean differences (SMDs), and combined data using fixed‐effect meta‐analysis. We estimated cost‐effectiveness by comparing inpatient CGA versus hospital admission without CGA in terms of cost per quality‐adjusted life year (QALY) gained, cost per life year (LY) gained, and cost per life year living at home (LYLAH) gained.
Main results
We included 29 trials recruiting 13,766 participants across nine, mostly high‐income countries. CGA increases the likelihood that patients will be alive and in their own homes at 3 to 12 months' follow‐up (risk ratio (RR) 1.06, 95% confidence interval (CI) 1.01 to 1.10; 16 trials, 6799 participants; high‐certainty evidence), results in little or no difference in mortality at 3 to 12 months' follow‐up (RR 1.00, 95% CI 0.93 to 1.07; 21 trials, 10,023 participants; high‐certainty evidence), decreases the likelihood that patients will be admitted to a nursing home at 3 to 12 months follow‐up (RR 0.80, 95% CI 0.72 to 0.89; 14 trials, 6285 participants; high‐certainty evidence) and results in little or no difference in dependence (RR 0.97, 95% CI 0.89 to 1.04; 14 trials, 6551 participants; high‐certainty evidence). CGA may make little or no difference to cognitive function (SMD ranged from ‐0.22 to 0.35 (5 trials, 3534 participants; low‐certainty evidence)). Mean length of stay ranged from 1.63 days to 40.7 days in the intervention group, and ranged from 1.8 days to 42.8 days in the comparison group. Healthcare costs per participant in the CGA group were on average GBP 234 (95% CI GBP ‐144 to GBP 605) higher than in the usual care group (17 trials, 5303 participants; low‐certainty evidence). CGA may lead to a slight increase in QALYs of 0.012 (95% CI ‐0.024 to 0.048) at GBP 19,802 per QALY gained (3 trials; low‐certainty evidence), a slight increase in LYs of 0.037 (95% CI 0.001 to 0.073), at GBP 6305 per LY gained (4 trials; low‐certainty evidence), and a slight increase in LYLAH of 0.019 (95% CI ‐0.019 to 0.155) at GBP 12,568 per LYLAH gained (2 trials; low‐certainty evidence). The probability that CGA would be cost‐effective at a GBP 20,000 ceiling ratio for QALY, LY, and LYLAH was 0.50, 0.89, and 0.47, respectively (17 trials, 5303 participants; low‐certainty evidence).
Authors' conclusions
Older patients are more likely to be alive and in their own homes at follow‐up if they received CGA on admission to hospital. We are uncertain whether data show a difference in effect between wards and teams, as this analysis was underpowered. CGA may lead to a small increase in costs, and evidence for cost‐effectiveness is of low‐certainty due to imprecision and inconsistency among studies. Further research that reports cost estimates that are setting‐specific across different sectors of care are required.
Flavonols are important ultraviolet light protectants in many plants and contribute substantially to the quality and health-promoting effects of fruits and derived plant products. To study the ...regulation of flavonol synthesis in fruit, we isolated and characterized the grapevine (Vitis vinifera 'Shiraz') R2R3-MYB transcription factor VvMYBF1. Transient reporter assays established VvMYBF1 to be a specific activator of flavonol synthase1 (VvFLS1) and several other promoters of grapevine and Arabidopsis (Arabidopsis thaliana) genes involved in flavonol synthesis. Expression of VvMYBF1 in the Arabidopsis mutant myb12 resulted in complementation of its flavonol-deficient phenotype and confirmed the function of VvMYBF1 as a transcriptional regulator of flavonol synthesis. Transcript analysis of VvMYBF1 throughout grape berry development revealed its expression during flowering and in skins of ripening berries, which correlates with the accumulation of flavonols and expression of VvFLS1. In addition to its developmental regulation, VvMYBF1 expression was light inducible, implicating VvMYBF1 in the control of VvFLS1 transcription. Sequence analysis of VvMYBF1 and VvFLS1 indicated conserved putative light regulatory units in promoters of both genes from different cultivars. By analysis of the VvMYBF1 amino acid sequence, we identified the previously described SG7 domain and an additional sequence motif conserved in several plant MYB factors. The described motifs have been used to identify MYB transcription factors from other plant species putatively involved in the regulation of flavonol biosynthesis. To our knowledge, this is the first functional characterization of a light-inducible MYB transcription factor controlling flavonol synthesis in fruit.
There is a clinical need for noninvasive biomarkers of tumor hypoxia for prognostic and predictive studies, radiotherapy planning, and therapy monitoring. Oxygen-enhanced MRI (OE-MRI) is an emerging ...imaging technique for quantifying the spatial distribution and extent of tumor oxygen delivery in vivo. In OE-MRI, the longitudinal relaxation rate of protons (ΔR1) changes in proportion to the concentration of molecular oxygen dissolved in plasma or interstitial tissue fluid. Therefore, well-oxygenated tissues show positive ΔR1. We hypothesized that the fraction of tumor tissue refractory to oxygen challenge (lack of positive ΔR1, termed "Oxy-R fraction") would be a robust biomarker of hypoxia in models with varying vascular and hypoxic features. Here, we demonstrate that OE-MRI signals are accurate, precise, and sensitive to changes in tumor pO2 in highly vascular 786-0 renal cancer xenografts. Furthermore, we show that Oxy-R fraction can quantify the hypoxic fraction in multiple models with differing hypoxic and vascular phenotypes, when used in combination with measurements of tumor perfusion. Finally, Oxy-R fraction can detect dynamic changes in hypoxia induced by the vasomodulator agent hydralazine. In contrast, more conventional biomarkers of hypoxia (derived from blood oxygenation-level dependent MRI and dynamic contrast-enhanced MRI) did not relate to tumor hypoxia consistently. Our results show that the Oxy-R fraction accurately quantifies tumor hypoxia noninvasively and is immediately translatable to the clinic.
Anthocyanins are secondary metabolites found in higher plants that contribute to the colors of flowers and fruits. In apples (Malus domestica Borkh.), several steps of the anthocyanin pathway are ...coordinately regulated, suggesting control by common transcription factors. A gene encoding an R2R3 MYB transcription factor was isolated from apple (cv Cripps' Pink) and designated MdMYB1. Analysis of the deduced amino acid sequence suggests that this gene encodes an ortholog of anthocyanin regulators in other plants. The expression of MdMYB1 in both Arabidopsis (Arabidopsis thaliana) plants and cultured grape cells induced the ectopic synthesis of anthocyanin. In the grape (Vitis vinifera) cells MdMYB1 stimulated transcription from the promoters of two apple genes encoding anthocyanin biosynthetic enzymes. In ripening apple fruit the transcription of MdMYB1 was correlated with anthocyanin synthesis in red skin sectors of fruit. When dark-grown fruit were exposed to sunlight, MdMYB1 transcript levels increased over several days, correlating with anthocyanin synthesis in the skin. MdMYB1 gene transcripts were more abundant in red skin apple cultivars compared to non-red skin cultivars. Several polymorphisms were identified in the promoter of MdMYB1. A derived cleaved amplified polymorphic sequence marker designed to one of these polymorphisms segregated with the inheritance of skin color in progeny from a cross of an unnamed red skin selection (a sibling of Cripps' Pink) and the non-red skin cultivar Golden Delicious. We conclude that MdMYB1 coordinately regulates genes in the anthocyanin pathway and the expression level of this regulator is the genetic basis for apple skin color.
Among the dramatic changes occurring during grape berry (Vitis vinifera) development, those affecting the flavonoid pathway have provoked a number of investigations in the last 10 years. In addition ...to producing several compounds involved in the protection of the berry and the dissemination of the seeds, final products of this pathway also play a critical role in berry and wine quality. In this article, we describe the cloning and functional characterization of VvMYB5b, a cDNA isolated from a grape berry (V. vinifera 'Cabernet Sauvignon') library. VvMYB5b encodes a protein belonging to the R2R3-MYB family of transcription factors and displays significant similarity with VvMYB5a, another MYB factor recently shown to regulate flavonoid synthesis in grapevine. The ability of VvMYB5a and VvMYB5b to activate the grapevine promoters of several structural genes of the flavonoid pathway was confirmed by transient expression of the corresponding cDNAs in grape cells. Overexpression of VvMYB5b in tobacco (Nicotiana tabacum) leads to an up-regulation of genes encoding enzymes of the flavonoid pathway and results in the accumulation of anthocyanin- and proanthocyanidin-derived compounds. The ability of VvMYB5b to regulate particularly the anthocyanin and the proanthocyanidin pathways is discussed in relation to other recently characterized MYB transcription factors in grapevine. Taken together, data presented in this article give insight into the transcriptional mechanisms associated with the regulation of the flavonoid pathway throughout grape berry development.
•We identified an R2R3 MYB transcription factor whichencodes an ortholog of the Arabidopsis flavonol regulators in buckwheat (Fagopyrum esculentum).•Expression of FeMYBF1 in a flavonol-deficient ...Arabidopsis triple mutant (myb11 myb12 myb111) restored flavonol synthesis.•Transient expression assays showed that FeMYBF1 activated the promoter of the Arabidopsis gene encoding AtFLS1.•FeMYBF1 also activated the promoters of buckwheat genes related to anthocyanin and proanthocyanidin synthesis such as dihydroflavonol 4-reductase (DFR) and leucoanthocyanidin dioxygenase (LDOX) in addition to genes encoding FLS.
Buckwheat (Fagopyrum esculentum) contains high amounts of flavonoids, especially flavonols (e.g., rutin), which are thought to be highly beneficial for human health. Little is known, however, about the regulation of flavonol synthesis in buckwheat. We identified a buckwheat gene encoding an R2R3 MYB transcription factor, and named this gene FeMYBF1. Analysis of the deduced amino acid sequence and phylogenetic analysis suggested that FeMYBF1 encodes an ortholog of the Arabidopsis flavonol regulators AtMYB11, AtMYB12 and AtMYB111. Expression of FeMYBF1 in a flavonol-deficient Arabidopsis triple mutant (myb11 myb12 myb111) restored flavonol synthesis. Constitutive expression of FeMYBF1 driven by the CaMV 35S promoter in Arabidopsis resulted in over-accumulation of flavonol glycosides and upregulation of the expression of AtFLS1. Transient expression assays showed that FeMYBF1 activated the promoter of the Arabidopsis gene encoding AtFLS1, and the promoters of buckwheat genes related to anthocyanin and proanthocyanidin synthesis such as dihydroflavonol 4-reductase (DFR) and leucoanthocyanidin dioxygenase (LDOX) in addition to genes encoding FLS. The results indicate that FeMYBF1 regulates flavonol synthesis and may have a role in synthesis of other flavonoid compounds, and also that buckwheat may have alternative pathway of flavonol synthesis through DFR and LDOX.
Most of the thousands of grapevine cultivars (Vitis vinifera L.) can be divided into two groups, red and white, based on the presence or absence of anthocyanin in the berry skin, which has been found ...from genetic experiments to be controlled by a single locus. A regulatory gene, VvMYBA1, which could activate anthocyanin biosynthesis in a transient assay, was recently shown not to be transcribed in white berries due to the presence of a retrotransposon in the promoter. We have found that the berry colour locus comprises two very similar genes, VvMYBA1 and VvMYBA2, located on a single bacterial artificial chromosome. Either gene can regulate colour in the grape berry. The white berry allele of VvMYBA2 is inactivated by two non-conservative mutations, one leads to an amino acid substitution and the other to a frame shift resulting in a smaller protein. Transient assays showed that either mutation removed the ability of the regulator to switch on anthocyanin biosynthesis. VvMYBA2 sequence analyses, together with marker information, confirmed that 55 white cultivars all contain the white berry allele, but not red berry alleles. These results suggest that all extant white cultivars of grape vines have a common origin. We conclude that rare mutational events occurring in two adjacent genes were essential for the genesis of the white grapes used to produce the white wines and white table grapes we enjoy today.
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