Reactive astrocytes potentiate tumor aggressiveness in a murine glioma resection and recurrence model

Surgical resection is a universal component of glioma therapy. Little is known about the postoperative microenvironment due to limited preclinical models. Thus, we sought to develop a glioma resection and recurrence model in syngeneic immune-competent mice to understand how surgical resection influences tumor biology and the local microenvironment

Core pathway mutations induce de-differentiation of murine astrocytes into glioblastoma stem cells that are sensitive to radiation but resistant to temozolomide

Glioma stem cells (GSCs) from human glioblastomas (GBMs) are resistant to radiation and chemotherapy and may drive recurrence. Treatment efficacy may depend on GSCs, expression of DNA repair enzymes such as methylguanine methyltransferase (MGMT), or transcriptome subtype

Modeling Astrocytoma Pathogenesis <em>In Vitro</em> and <em>In Vivo</em> Using Cortical Astrocytes or Neural Stem Cells from Conditional, Genetically Engineered Mice

Current astrocytoma models are limited in their ability to define the roles of oncogenic mutations in specific brain cell types during disease pathogenesis and their utility for preclinical drug development. In order to design a better model system for these applications, phenotypically wild-type cortical astrocytes and neural stem cells (NSC) from conditional, genetically engineered mice (GEM) that harbor various combinations of floxed oncogenic alleles were harvested and grown in culture. Genetic recombination was induced in vitro using adenoviral Cre-mediated recombination, resulting in expression of mutated oncogenes and deletion of tumor suppressor genes. The phenotypic consequences of these mutations were defined by measuring proliferation, transformation, and drug response in vitro. Orthotopic allograft models, whereby transformed cells are stereotactically injected into the brains of immune-competent, syngeneic littermates, were developed to define the role of oncogenic mutations and cell type on tumorigenesis in vivo. Unlike most established human glioblastoma cell line xenografts, injection of transformed GEM-derived cortical astrocytes into the brains of immune-competent littermates produced astrocytomas, including the most aggressive subtype, glioblastoma, that recapitulated the histopathological hallmarks of human astrocytomas, including diffuse invasion of normal brain parenchyma. Bioluminescence imaging of orthotopic allografts from transformed astrocytes engineered to express luciferase was utilized to monitor in vivo tumor growth over time. Thus, astrocytoma models using astrocytes and NSC harvested from GEM with conditional oncogenic alleles provide an integrated system to study the genetics and cell biology of astrocytoma pathogenesis in vitro and in vivo and may be useful in preclinical drug development for these devastating diseases

Cooperativity between MAPK and PI3K signaling activation is required for glioblastoma pathogenesis

Glioblastoma (GBM) genomes feature recurrent genetic alterations that dysregulate core intracellular signaling pathways, including the G1/S cell cycle checkpoint and the MAPK and PI3K effector arms of receptor tyrosine kinase (RTK) signaling. Elucidation of the phenotypic consequences of activated RTK effectors is required for the design of effective therapeutic and diagnostic strategies

Modeling Astrocytoma Pathogenesis <em>In Vitro</em> and <em>In Vivo</em> Using Cortical Astrocytes or Neural Stem Cells from Conditional, Genetically Engineered Mice

Current astrocytoma models are limited in their ability to define the roles of oncogenic mutations in specific brain cell types during disease pathogenesis and their utility for preclinical drug development. In order to design a better model system for these applications, phenotypically wild-type cortical astrocytes and neural stem cells (NSC) from conditional, genetically engineered mice (GEM) that harbor various combinations of floxed oncogenic alleles were harvested and grown in culture. Genetic recombination was induced in vitro using adenoviral Cre-mediated recombination, resulting in expression of mutated oncogenes and deletion of tumor suppressor genes. The phenotypic consequences of these mutations were defined by measuring proliferation, transformation, and drug response in vitro. Orthotopic allograft models, whereby transformed cells are stereotactically injected into the brains of immune-competent, syngeneic littermates, were developed to define the role of oncogenic mutations and cell type on tumorigenesis in vivo. Unlike most established human glioblastoma cell line xenografts, injection of transformed GEM-derived cortical astrocytes into the brains of immune-competent littermates produced astrocytomas, including the most aggressive subtype, glioblastoma, that recapitulated the histopathological hallmarks of human astrocytomas, including diffuse invasion of normal brain parenchyma. Bioluminescence imaging of orthotopic allografts from transformed astrocytes engineered to express luciferase was utilized to monitor in vivo tumor growth over time. Thus, astrocytoma models using astrocytes and NSC harvested from GEM with conditional oncogenic alleles provide an integrated system to study the genetics and cell biology of astrocytoma pathogenesis in vitro and in vivo and may be useful in preclinical drug development for these devastating diseases

Psychological Distress Prevalence and Associated Stressors and Supports Among Urban-Displaced Congolese Adults in Kenya

Background: There is limited understanding of the prevalence of psychological distress and associated stressors and supports among displaced adults in low- and middle-income first asylum countries. Method: This article reports the findings of a cross-sectional study. We recruited 245 Congolese adults (18–80 years) residing in Nairobi, Kenya using snowball sampling. Data were collected using an interviewer-administered questionnaire consisting of sociodemographic characteristics, the Self-Reporting Questionnaire (SRQ-20), and a locally developed stressors and supports survey. We used multivariable logistic regression to examine associations among sociodemographic, stressor, and support variables and the likelihood of experiencing psychological distress. Results: More than half of the participants (52.8%) reported symptoms indicative of psychological distress. Factors associated with increased psychological distress included perceiving to have a useful role in one’s family or community, AOR = 1.85; 95% CI [1.1.17, 3.11], p = .012, feeling confused or not knowing what to do, AOR = 2.13; 95% CI [1.20, 4.6], p = .014, and feeling afraid to leave home for medical/health care to help with an illness, AOR = 1.57; 95% CI [1.17, 2.15], p \u3c .01. Additionally, ethnic Banyamulenge Congolese adults without legal refugee status had an increased likelihood of experiencing psychological distress, AOR = .07; 95% CI [0, .74], p = .035. Conclusion: Future research is warranted to understand how to implement targeted mental health and psychosocial support (MHPSS) to improve urban-displaced adults’ sense of safety and belonging. Our findings suggest that legal refugee status is an important structural determinant of mental health, which should be considered in MHPSS practice and policy

Core pathway mutations induce de-differentiation of murine astrocytes into glioblastoma stem cells that are sensitive to radiation but resistant to temozolomide

BACKGROUND: Glioma stem cells (GSCs) from human glioblastomas (GBMs) are resistant to radiation and chemotherapy and may drive recurrence. Treatment efficacy may depend on GSCs, expression of DNA repair enzymes such as methylguanine methyltransferase (MGMT), or transcriptome subtype. METHODS: To model genetic alterations in human GBM core signaling pathways, we induced Rb knockout, Kras activation, and Pten deletion mutations in cortical murine astrocytes. Neurosphere culture, differentiation, and orthotopic transplantation assays were used to assess whether these mutations induced de-differentiation into GSCs. Genome-wide chromatin landscape alterations and expression profiles were examined by formaldehyde-assisted isolation of regulatory elements (FAIRE) seq and RNA-seq. Radiation and temozolomide efficacy were examined in vitro and in an allograft model in vivo. Effects of radiation on transcriptome subtype were examined by microarray expression profiling. RESULTS: Cultured triple mutant astrocytes gained unlimited self-renewal and multilineage differentiation capacity. These cells harbored significantly altered chromatin landscapes that were associated with downregulation of astrocyte- and upregulation of stem cell-associated genes, particularly the Hoxa locus of embryonic transcription factors. Triple-mutant astrocytes formed serially transplantable glioblastoma allografts that were sensitive to radiation but expressed MGMT and were resistant to temozolomide. Radiation induced a shift in transcriptome subtype of GBM allografts from proneural to mesenchymal. CONCLUSION: A defined set of core signaling pathway mutations induces de-differentiation of cortical murine astrocytes into GSCs with altered chromatin landscapes and transcriptomes. This non-germline genetically engineered mouse model mimics human proneural GBM on histopathological, molecular, and treatment response levels. It may be useful for dissecting the mechanisms of treatment resistance and developing more effective therapies

Core pathway mutations induce de-differentiation of murine astrocytes into glioblastoma stem cells that are sensitive to radiation but resistant to temozolomide

general view, Center Garden, looking north on a cross axi