EGFRvIII deletion mutations in pediatric high-grade glioma and response to targeted therapy in pediatric glioma cell lines

Purpose: The epidermal growth factor receptor (EGFR) is amplified and overexpressed in adult glioblastoma, with response to targeted inhibition dependent on the underlying biology of the disease. EGFR has thus far been considered to play a less important role in pediatric glioma, although extensive data are lacking. We have sought to clarify the role of EGFR in pediatric high-grade glioma (HGG). Experimental Design: We retrospectively studied a total of 90 archival pediatric HGG specimens for EGFR protein overexpression, gene amplification, and mutation and assessed the in vitro sensitivity of pediatric glioma cell line models to the small-molecule EGFR inhibitor erlotinib. Results: Amplification was detected in 11% of cases, with corresponding overexpression of the receptor. No kinase or extracellular domain mutations were observed; however, 6 of 35 (17%) cases harbored the EGFRvIII deletion, including two anaplastic oligodendrogliomas and a gliosarcoma overexpressing EGFRvIII in the absence of gene amplification and coexpressing platelet-derived growth factor receptor α. Pediatric glioblastoma cells transduced with wild-type or deletion mutant EGFRvIII were not rendered more sensitive to erlotinib despite expressing wild-type PTEN. Phosphorylated receptor tyrosine kinase profiling showed a specific activation of platelet-derived growth factor receptor α/β in EGFRvIII-transduced pediatric glioblastoma cells, and targeted coinhibition with erlotinib and imatinib leads to enhanced efficacy in this model. Conclusions: These data identify an elevated frequency of EGFR gene amplification and EGFRvIII mutation in pediatric HGG than previously recognized and show the likely necessity of targeting multiple genetic alterations in the tumors of these children.Cancer Research UK grants C1178/A10294, C309/A2187, and C309/A8274; Oak Foundation (L. Marshall); La Fondation de France (N. Gaspar); and Breakthrough Breast Cancer (J.S. Reis-Filho). We acknowledge NHS funding to the National Institute for Health Research Biomedical Research Centre

Frequent Long-Range Epigenetic Silencing of Protocadherin Gene Clusters on Chromosome 5q31 in Wilms' Tumor

Wilms' tumour (WT) is a pediatric tumor of the kidney that arises via failure of the fetal developmental program. The absence of identifiable mutations in the majority of WTs suggests the frequent involvement of epigenetic aberrations in WT. We therefore conducted a genome-wide analysis of promoter hypermethylation in WTs and identified hypermethylation at chromosome 5q31 spanning 800 kilobases (kb) and more than 50 genes. The methylated genes all belong to α-, β-, and γ-protocadherin (PCDH) gene clusters (Human Genome Organization nomenclature PCDHA@, PCDHB@, and PCDHG@, respectively). This demonstrates that long-range epigenetic silencing (LRES) occurs in developmental tumors as well as in adult tumors. Bisulfite polymerase chain reaction analysis showed that PCDH hypermethylation is a frequent event found in all Wilms' tumor subtypes. Hypermethylation is concordant with reduced PCDH expression in tumors. WT precursor lesions showed no PCDH hypermethylation, suggesting that de novo PCDH hypermethylation occurs during malignant progression. Discrete boundaries of the PCDH domain are delimited by abrupt changes in histone modifications; unmethylated genes flanking the LRES are associated with permissive marks which are absent from methylated genes within the domain. Silenced genes are marked with non-permissive histone 3 lysine 9 dimethylation. Expression analysis of embryonic murine kidney and differentiating rat metanephric mesenchymal cells demonstrates that Pcdh expression is developmentally regulated and that Pcdhg@ genes are expressed in blastemal cells. Importantly, we show that PCDHs negatively regulate canonical Wnt signalling, as short-interfering RNA–induced reduction of PCDHG@ encoded proteins leads to elevated β-catenin protein, increased β-catenin/T-cell factor (TCF) reporter activity, and induction of Wnt target genes. Conversely, over-expression of PCDHs suppresses β-catenin/TCF-reporter activity and also inhibits colony formation and growth of cancer cells in soft agar. Thus PCDHs are candidate tumor suppressors that modulate regulatory pathways critical in development and disease, such as canonical Wnt signaling

Inflammatory and hemostatic responses to repeated mental stress: Individual stability and habituation over time.

An important assumption underlying psychobiological studies relating stress reactivity with disease risk is that individuals are characterized by stable response profiles that can be reliably assessed using acute psychophysiological stress testing. Previous research has mainly focused on the stability of cardiovascular, neuroendocrine, and cellular immune responses to repeated stressors, and less attention has been given to inflammatory and platelet responses. We therefore examined both average stability and individual test–retest stability of cardiovascular, neuroendocrine, hemostatic, inflammatory, and subjective responses to mental stress over two repeated stress sessions, four weeks apart. Ninety-one healthy, non-smoking men (mean age 33.2 years) completed a 3-min speech task followed by a 5-min mirror tracing task on two separate occasions. Blood samples were taken at baseline and 10 min after the stress tasks while cardiovascular activity, saliva samples, and subjective ratings were measured repeatedly. There was significant cardiovascular and cortisol activation to the stressors and stress-induced increases in plasma C-reactive protein, von Willebrand factor antigen, and platelet activation indexed by leukocyte–platelet aggregates. The magnitude of stress responses did not differ between sessions in any variable. Significant test–retest correlations between sessions were observed for baseline and stress values of all variables (r = 0.47–0.74, p < .001), but reactivity (change scores) for C-reactive protein, von Willebrand factor, cortisol, and platelet activation were not significantly correlated. Our results demonstrate that the stress-induced responses did not habituate between sessions, though the small magnitude of acute inflammatory, cortisol, and platelet responses limits the test–retest reliability of stress reactivity assessments

Inflammatory and hemostatic responses to repeated mental stress: Individual stability and habituation over time

An important assumption underlying psychobiological studies relating stress reactivity with disease risk is that individuals are characterized by stable response profiles that can be reliably assessed using acute psychophysiological stress testing. Previous research has mainly focused on the stability of cardiovascular, neuroendocrine, and cellular immune responses to repeated stressors, and less attention has been given to inflammatory and platelet responses. We therefore examined both average stability and individual test–retest stability of cardiovascular, neuroendocrine, hemostatic, inflammatory, and subjective responses to mental stress over two repeated stress sessions, four weeks apart. Ninety-one healthy, non-smoking men (mean age 33.2 years) completed a 3-min speech task followed by a 5-min mirror tracing task on two separate occasions. Blood samples were taken at baseline and 10 min after the stress tasks while cardiovascular activity, saliva samples, and subjective ratings were measured repeatedly. There was significant cardiovascular and cortisol activation to the stressors and stress-induced increases in plasma C-reactive protein, von Willebrand factor antigen, and platelet activation indexed by leukocyte–platelet aggregates. The magnitude of stress responses did not differ between sessions in any variable. Significant test–retest correlations between sessions were observed for baseline and stress values of all variables (r = 0.47–0.74, p < .001), but reactivity (change scores) for C-reactive protein, von Willebrand factor, cortisol, and platelet activation were not significantly correlated. Our results demonstrate that the stress-induced responses did not habituate between sessions, though the small magnitude of acute inflammatory, cortisol, and platelet responses limits the test–retest reliability of stress reactivity assessments

Association between coffee consumption and markers of inflammation and cardiovascular function during mental stress

Background: Coffee is widely consumed in the Western diet and therefore has important implications for public health. Research findings pertaining to the effects of coffee consumption on cardiovascular health are conflicting, and the role of caffeine is not clear. Objective: To examine the relationship between coffee intake, inflammation and cardiovascular function at baseline and during mental stress, both cross-sectionally and after a 4-week period of withdrawal of coffee during which intake of caffeine was maintained. Methods: Eighty-five healthy, non-smoking men with varying coffee-drinking habits were recruited. Blood pressure, heart rate, and markers of inflammation [C-reactive protein (CRP), von Willebrand factor antigen (vWF)], were measured at baseline and during mental stress. These measures were repeated after a 4-week period of withdrawal of coffee, during which intake of caffeine was maintained. Habitual levels of coffee and caffeine consumption were assessed from a self-reported questionnaire, and saliva samples for the analysis of caffeine concentrations were collected regularly throughout the period of withdrawal, to confirm compliance. Results: Multiple linear regression analysis of pre-withdrawal data, adjusted for age, body mass index and intake of tea, red wine, fruit, vegetables, oily fish and dietary supplements revealed that coffee consumption was positively related to baseline systolic blood pressure, and increased heart rate and vWF responses to mental stress. Four weeks after withdrawal of coffee, the heightened vWF and heart rate responses to stress in habitual coffee drinkers persisted, whereas baseline systolic blood pressure had decreased. Total caffeine intake was unrelated to any measures of physiological function. Conclusions: Habitual coffee consumption is associated with heightened acute vascular inflammatory responses to mental stress, although these effects are not affected by short-term abstinence from coffee. These findings suggest that the relationship between coffee and markers of cardiovascular risk may be explained by residual or unmeasured confounding factors

Association between coffee consumption and markers of inflammation and cardiovascular function during mental stress

Background Coffee is widely consumed in the Western diet and therefore has important implications for public health. Research findings pertaining to the effects of coffee consumption on cardiovascular health are conflicting, and the role of caffeine is not clear.Objective To examine the relationship between coffee intake, inflammation and cardiovascular function at baseline and during mental stress, both cross-sectionally and after a 4-week period of withdrawal of coffee during which intake of caffeine was maintained.Methods Eighty-five healthy, non-smoking men with varying coffee-drinking habits were recruited. Blood pressure, heart rate, and markers of inflammation [C-reactive protein (CRP), von Willebrand factor antigen (vWF)], were measured at baseline and during mental stress. These measures were repeated after a 4-week period of withdrawal of coffee, during which intake of caffeine was maintained. Habitual levels of coffee and caffeine consumption were assessed from a self-reported questionnaire, and saliva samples for the analysis of caffeine concentrations were collected regularly throughout the period of withdrawal, to confirm compliance.Results Multiple linear regression analysis of prewithdrawal data, adjusted for age, body mass index and intake of tea, red wine, fruit, vegetables, oily fish and dietary supplements revealed that coffee consumption was positively related to baseline systolic blood pressure, and increased heart rate and vWF responses to mental stress. Four weeks after withdrawal of coffee, the heightened vWF and heart rate responses to stress in habitual coffee drinkers persisted, whereas baseline systolic blood pressure had decreased. Total caffeine intake was unrelated to any measures of physiological function. Conclusions Habitual coffee consumption is associated with heightened acute vascular inflammatory responses to mental stress, although these effects are not affected by short-term abstinence from coffee. These findings suggest that the relationship between coffee and markers of cardiovascular risk may be explained by residual or unmeasured confounding factors

Expression of hepatocyte growth factor and its receptor Met in Wilms' tumors and nephrogenic rests reflects their roles in kidney development

Purpose: Hepatocyte growth factor (HGF) and its receptor Met are known to play diverse roles in both organogenesis and cancer. Wilms' tumor (WT) is a prototype for the link between abrogated development and neoplasia, with dysregulation of growth factor/receptor pathways playing key roles. Despite this, an understanding of the HGF/Met axis in the process is lacking. Experimental Design: Observing copy number alterations at the loci for these genes in WTs and their precursor lesions nephrogenic rests, we examined protein expression by immunohistochemistry and investigated the effects of HGF on an in vitro model of kidney development. Results: HGF was preferentially expressed in the blastemal cells of nephrogenic rests but not WTs. Met expression was infrequent and restricted to well-differentiated epithelial cells and stroma in both lesions. In an independent cohort of favorable histology WTs on a tissue microarray, HGF was expressed in 15 of 193 (8%) cases and correlated with a predominance of epithelial cells, whereas Met expression was observed in 25 of 179 (14%) cases and was associated with stromal subtypes. In a mouse mesonephric cell line model, we observed Met expression in culture conditions reflecting both mesenchymal and epithelial differentiation, whereas HGF was up-regulated in association with acquisition of a more epithelial-like phenotype. This could be mimicked by exogenous exposure of mesenchymal-like cells to recombinant HGF. Conclusions: These data show that the relatively infrequent expression of HGF and Met in WT tumorigenesis reflects their roles in nephrogenesis, particularly the mesenchymal-to-epithelial transition, rather than a dependence on oncogenic signaling pathways