Project description:The determinants of the genetic complexity of Glioblastoma are poorly understood. We generated murine Glioblastomas by transforming glial progenitors in the adult brain with PDGF expression and PTEN deletion +/- p53 deletion. PDGF+PTEN-/- tumors developed additional deletions of specific genes in up to 100% of the tumors, whereas PDGF+PTEN-/-p53-/- tumors did not. Cross-species comparison with data from tCGA database and published in Verhaak, 2010, showed that consistent genetic deletions observed in mouse tumors were specific to human Proneural Glioblastoma. These findings show that the genetic alterations that accumulate during tumor progression are determined by the initiating genetic alterations and by the cellular context in which they occur.
Project description:The determinants of the genetic complexity of Glioblastoma are poorly understood. We generated murine Glioblastomas by transforming glial progenitors in the adult brain with PDGF expression and PTEN deletion +/- p53 deletion. PDGF+PTEN-/- tumors developed additional deletions of specific genes in up to 100% of the tumors, whereas PDGF+PTEN-/-p53-/- tumors did not. Cross-species comparison with data from tCGA database and published in Verhaak, 2010, showed that consistent genetic deletions observed in mouse tumors were specific to human Proneural Glioblastoma. These findings show that the genetic alterations that accumulate during tumor progression are determined by the initiating genetic alterations and by the cellular context in which they occur. Murine gliomas were induced in vivo by retroviral mediated PDGF overexpression, PTEN deletion with or without p53 deletion using Cre/lox system. Tumors were subsequently harvested for sequencing and aCGH analysis. Paired liver DNA was used for hybridization. For PDGF+PTEN-/- tumors, different timepoints were obtained including 21, 35 days post tumor induction, as well as endstage tumors.
Project description:Background Tumor heterogeneity is a major obstacle for finding effective treatment of Glioblastoma (GBM). Based on global expression analysis, GBM can be classified into distinct subtypes: Proneural, Neural, Classical and Mesenchymal. The signatures of these different tumor subtypes may reflect the phenotypes of cells giving rise to them. However, the experimental evidence connecting any specific subtype of GBM to particular cells of origin is lacking. In addition, it is unclear how different genetic alterations interact with cells of origin in determining tumor heterogeneity. This issue cannot be addressed by studying end-stage human tumors. Methodology/Principal Findings To address this issue, we used retroviruses to deliver transforming genetic lesions to glial progenitors in adult mouse brain. We compared the resulting tumors to human GBM. We found that different initiating genetic lesions gave rise to tumors with different growth rates. However all mouse tumors closely resembled the human Proneural GBM. Comparative analysis of these mouse tumors allowed us to identify a set of genes whose expression in humans with Proneural GBM correlates with survival. Conclusions/Significance This study offers insights into the relationship between adult glial progenitors and Proneural GBM, and allows us to identify molecular alterations that lead to more aggressive tumor growth. In addition, we present a new preclinical model that can be used to test treatments directed at a specific type of GBM in future studies. Gene expression profiling was performed on 20 tumors (12 Ptenf/f and 8 Ptenf/f; p53f/f) and 3 normal brains from mice. End stage tumors were used for expression array analysis. The platform used was Affymetrix GeneChip Mouse Genome 430A 2.0 Array. The microarray labeling, hybridization and quality controls were performed by following Affymetrix protocol.
Project description:Background Tumor heterogeneity is a major obstacle for finding effective treatment of Glioblastoma (GBM). Based on global expression analysis, GBM can be classified into distinct subtypes: Proneural, Neural, Classical and Mesenchymal. The signatures of these different tumor subtypes may reflect the phenotypes of cells giving rise to them. However, the experimental evidence connecting any specific subtype of GBM to particular cells of origin is lacking. In addition, it is unclear how different genetic alterations interact with cells of origin in determining tumor heterogeneity. This issue cannot be addressed by studying end-stage human tumors. Methodology/Principal Findings To address this issue, we used retroviruses to deliver transforming genetic lesions to glial progenitors in adult mouse brain. We compared the resulting tumors to human GBM. We found that different initiating genetic lesions gave rise to tumors with different growth rates. However all mouse tumors closely resembled the human Proneural GBM. Comparative analysis of these mouse tumors allowed us to identify a set of genes whose expression in humans with Proneural GBM correlates with survival. Conclusions/Significance This study offers insights into the relationship between adult glial progenitors and Proneural GBM, and allows us to identify molecular alterations that lead to more aggressive tumor growth. In addition, we present a new preclinical model that can be used to test treatments directed at a specific type of GBM in future studies.
Project description:Significant qualitative and quantitative differences exist between humans and the animal models used in research. However, significant quantitative and qualitative differences exist between humans and the animal models used in research. This is as a result of genetic variation between human and the laboratory animal. Therefore the development of a system that would allow the assessment of all molecular differences between species after drug exposure would have a significant impact on drug evaluation for toxicity and efficacy. Here we describe a cross-species microarray methodology that identifies and selects orthologous probes after cross-species sequence comparison to develop an orthologous cross-species gene expression analysis tool. The assumptions made by the use of this orthologous gene expression strategy for cross-species extrapolation is that; conserved changes in gene expression equate to conserved pharmacodynamic endpoints. This assumption is supported by the fact that evolution and selection have maintained the structure and function of many biochemical pathways over time, resulting in the conservation of many important processes. We demonstrate this difference using a cross-species methodology by investigating species specific differences of the peroxisome proliferator activator receptor (PPAR) alpha in rat and human.
Project description:Significant qualitative and quantitative differences exist between humans and the animal models used in research. However, significant quantitative and qualitative differences exist between humans and the animal models used in research. This is as a result of genetic variation between human and the laboratory animal. Therefore the development of a system that would allow the assessment of all molecular differences between species after drug exposure would have a significant impact on drug evaluation for toxicity and efficacy. Here we describe a cross-species microarray methodology that identifies and selects orthologous probes after cross-species sequence comparison to develop an orthologous cross-species gene expression analysis tool. The assumptions made by the use of this orthologous gene expression strategy for cross-species extrapolation is that; conserved changes in gene expression equate to conserved pharmacodynamic endpoints. This assumption is supported by the fact that evolution and selection have maintained the structure and function of many biochemical pathways over time, resulting in the conservation of many important processes. We demonstrate this difference using a cross-species methodology by investigating species specific differences of the peroxisome proliferator activator receptor (PPAR) alpha in rat and human.
Project description:Significant qualitative and quantitative differences exist between humans and the animal models used in research. However, significant quantitative and qualitative differences exist between humans and the animal models used in research. This is as a result of genetic variation between human and the laboratory animal. Therefore the development of a system that would allow the assessment of all molecular differences between species after drug exposure would have a significant impact on drug evaluation for toxicity and efficacy. Here we describe a cross-species microarray methodology that identifies and selects orthologous probes after cross-species sequence comparison to develop an orthologous cross-species gene expression analysis tool. The assumptions made by the use of this orthologous gene expression strategy for cross-species extrapolation is that; conserved changes in gene expression equate to conserved pharmacodynamic endpoints. This assumption is supported by the fact that evolution and selection have maintained the structure and function of many biochemical pathways over time, resulting in the conservation of many important processes. We demonstrate this difference using a cross-species methodology by investigating species specific differences of the peroxisome proliferator activator receptor (PPAR) alpha in rat and human. Rat primary hepatocytes were treated with 30 µM, 100 µM EMD and 0.1% DMSO as vehicle control. All samples were incubated at 24hr and 72hr intervals before RNA extrations and hybridization onto Affymetrix Rat microarrays.
Project description:Significant qualitative and quantitative differences exist between humans and the animal models used in research. However, significant quantitative and qualitative differences exist between humans and the animal models used in research. This is as a result of genetic variation between human and the laboratory animal. Therefore the development of a system that would allow the assessment of all molecular differences between species after drug exposure would have a significant impact on drug evaluation for toxicity and efficacy. Here we describe a cross-species microarray methodology that identifies and selects orthologous probes after cross-species sequence comparison to develop an orthologous cross-species gene expression analysis tool. The assumptions made by the use of this orthologous gene expression strategy for cross-species extrapolation is that; conserved changes in gene expression equate to conserved pharmacodynamic endpoints. This assumption is supported by the fact that evolution and selection have maintained the structure and function of many biochemical pathways over time, resulting in the conservation of many important processes. We demonstrate this difference using a cross-species methodology by investigating species specific differences of the peroxisome proliferator activator receptor (PPAR) alpha in rat and human. Human primary hepatocytes were treated with 30 uM, 100 uM EMD and 0.1% DMSO as vehicle control. All samples were incubated at 24hr and 72hr intervals before RNA extractions and hybridization onto Affymetrix human microarrays.