RESUMO
Recent work in human glioblastoma (GBM) has documented recurrent mutations in the histone chaperone protein ATRX. We developed an animal model of ATRX-deficient GBM and showed that loss of ATRX reduces median survival and increases genetic instability. Further, analysis of genome-wide data for human gliomas showed that ATRX mutation is associated with increased mutation rate at the single-nucleotide variant (SNV) level. In mouse tumors, ATRX deficiency impairs nonhomologous end joining and increases sensitivity to DNA-damaging agents that induce double-stranded DNA breaks. We propose that ATRX loss results in a genetically unstable tumor, which is more aggressive when left untreated but is more responsive to double-stranded DNA-damaging agents, resulting in improved overall survival.
Assuntos
Neoplasias Encefálicas/patologia , Reparo do DNA por Junção de Extremidades , DNA Helicases/deficiência , Glioma/patologia , Proteínas Nucleares/deficiência , Animais , Neoplasias Encefálicas/genética , Proliferação de Células , Cromossomos de Mamíferos/genética , Variações do Número de Cópias de DNA/genética , Dano ao DNA , DNA Helicases/genética , DNA Helicases/metabolismo , Modelos Animais de Doenças , Glioma/genética , Humanos , Camundongos , Instabilidade de Microssatélites , Mutação/genética , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Polimorfismo de Nucleotídeo Único/genética , Análise de Sobrevida , Homeostase do Telômero , Transposases/metabolismo , Proteína Nuclear Ligada ao XRESUMO
Glioblastoma multiforme (GBM) is the most common and the most aggressive type of brain cancer; the median survival time from the time of diagnosis is approximately one year. GBM is characterized by the hallmarks of rapid proliferation and aggressive invasion. miR-451 is known to play a key role in glioblastoma by modulating the balance of active proliferation and invasion in response to metabolic stress in the microenvironment. The present paper develops a mathematical model of GBM evolution which focuses on the relative balance of growth and invasion. In the present work we represent the miR-451/AMPK pathway by a simple model and show how the effects of glucose on cells need to be "refined" by taking into account the recent history of glucose variations. The simulations show how variations in glucose significantly affect the level of miR-451 and, in turn, cell migration. The model predicts that oscillations in the levels of glucose increase the growth of the primary tumor. The model also suggests that drugs which upregulate miR-451, or block other components of the CAB39/AMPK pathway, will slow down glioma cell migration. The model provides an explanation for the growth-invasion cycling patterns of glioma cells in response to high/low glucose uptake in microenvironment in vitro, and suggests new targets for drugs, associated with miR-451 upregulation.