Project description:Diffuse intrinsic pontine glioma (DIPG) is one of the most devastating of paediatric malignancies and one for which no effective therapy exists. A major contributor to the failure of therapeutic trials is the assumption that biologic properties of brainstem tumours in children are identical to cerebral high-grade gliomas of adults. A better understanding of the biology of DIPG itself is needed in order to develop agents targeted more specifically to these childrenâs disease. Here we address this lack of knowledge by performing the first high-resolution SNP-based DNA microarray analysis of a series of DIPGs. Eleven samples (nine post-mortem and two pre-treatment surgical samples), the largest series thus far examined, were hybridized to Affymetrix SNP arrays (250k or 6.0). The study was approved by the Research Ethics Board at our institution (Hospital for Sick Children, Toronto, Ontario, Canada). All Array findings were validated using quantitative-PCR, fluorescence in-situ hybridization, immunohistochemistry and/or microsatellite analysis. Analysis of DIPG copy number alterations showed recurrent changes distinct from those of paediatric supratentorial high-grade astrocytomas. 36% of DIPGs had gains in PDGFRA and all showed PDGF-R-α expression. Gains in PARP-1 were identified in 3 cases. Pathway analysis revealed genes with loss of heterozygosity were enriched for DNA repair pathways. Our data provides the first, comprehensive high-resolution genomic analysis of paediatric DIPG. Our findings of recurrent involvement of the PDGFR pathway as well as defects in DNA repair pathways coupled with gain of PARP-1 highlight two potential, biologically-based, therapeutic targets directed specifically at this devastating disease. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from snap frozen biopsy and autopsy brain tissue from DIPG patients. Copy number analysis of Affymetrix 250K and 6.0 SNP arrays was performed for 11 paediatric DIPG samples, 7 matched normal brain samples, and HapMap samples.
Project description:Diffuse intrinsic pontine glioma (DIPG) is one of the most devastating of paediatric malignancies and one for which no effective therapy exists. A major contributor to the failure of therapeutic trials is the assumption that biologic properties of brainstem tumours in children are identical to cerebral high-grade gliomas of adults. A better understanding of the biology of DIPG itself is needed in order to develop agents targeted more specifically to these children’s disease. Here we address this lack of knowledge by performing the first high-resolution SNP-based DNA microarray analysis of a series of DIPGs. Eleven samples (nine post-mortem and two pre-treatment surgical samples), the largest series thus far examined, were hybridized to Affymetrix SNP arrays (250k or 6.0). The study was approved by the Research Ethics Board at our institution (Hospital for Sick Children, Toronto, Ontario, Canada). All Array findings were validated using quantitative-PCR, fluorescence in-situ hybridization, immunohistochemistry and/or microsatellite analysis. Analysis of DIPG copy number alterations showed recurrent changes distinct from those of paediatric supratentorial high-grade astrocytomas. 36% of DIPGs had gains in PDGFRA and all showed PDGF-R-α expression. Gains in PARP-1 were identified in 3 cases. Pathway analysis revealed genes with loss of heterozygosity were enriched for DNA repair pathways. Our data provides the first, comprehensive high-resolution genomic analysis of paediatric DIPG. Our findings of recurrent involvement of the PDGFR pathway as well as defects in DNA repair pathways coupled with gain of PARP-1 highlight two potential, biologically-based, therapeutic targets directed specifically at this devastating disease.
Project description:Alkylating agents are a frontline therapy for the treatment of several cancers including pediatric glioblastoma, a devastating lethal tumor in children. Unfortunately, many tumors are resistant to this therapy. We sought to identify ways of sensitizing tumor cells to alkylating agents while leaving normal cells unharmed; increasing therapeutic response while minimizing toxicity. Here we report using a siRNA screen targeting over 240 DNA damage response genes identified novel sensitizers to alkylating agents. In particular the base excision repair (BER) pathway, including 3-methylpurine-DNA glycosylase (MPG), as well as ataxia telangiectasia mutated (ATM) were identified in our screen. Interestingly, we identified MPG as a direct novel substrate of ATM. ATM-mediated phosphorylation of MPG was required for enhanced MPG function. Importantly, combined inhibition or loss of MPG and ATM resulted in increased alkylating agent-induced cytotoxicity in vitro and prolonged survival in vivo. The discovery of the ATM-MPG axis will lead to improved treatment of alkylating agent-resistant tumors. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from snap frozen biopsy and surgical brain tissue from paediatric high grade gliomas Copy number analysis on Affymetrix SNP 250K arrays was performed for 35 paediatric high grade glioma samples and HapMap samples.
Project description:We have used Illumina Infinium HumanMethylation450 BeadChip array profiling to profile paediatric high grade gliomas and diffuse intrinsic pontine gliomas. The 450K methylation array is being used to separate brain tumour samples on the basis of their methylation profiles which represent the cell of origin the time and place in which tumours arise. Methylation arrays provide data for an integrated molecular diagnosis of brain tumours and define specific molecular subgroups and subtypes of high grade gliomas carrying distinct driver mutations and patterns of somatic alterations. These data form part of an integrated meta-analysis of high grade gliomas in children combining DNA copy number, methylation and high throughput sequencing datasets.
Project description:250k Sty, 250k Nsp, 250k Hind and 250k Xba Affymetrix SNP arrays for 50 leukemia remission samples used as controls for copy number analysis for GSE9109 and GSE9112. Keywords: Acute leukemia, BCR-ABL1, chronic myeloid leukemia, copy number analysis, loss-of-heterozygosity, genomics *** Due to privacy concerns, the primary SNP array data is no longer available with unrestricted access. Individuals wishing to obtain this data for research purposes may request access using the Web links below. ***