|Application:||Gene expression microarray analysis, SNP array data analysis|
|Number of samples:||25|
|Release date:||May 1 2008|
|Last update date:||Dec 22 2017|
|Dataset link||Whole-Genome Profiling in Liposarcomas Reveals Genetic Alterations Common to Specific Telomere Maintenance Mechanisms|
Goal: To study telomere maintenance and genetic alterations in liposarcoma using Affymetrix Mapping 50K Xba 240 GeneChip. Brief description: Telomere attrition ultimately leads to the activation of protective cellular responses such as apoptosis or senescence. Impairment of such mechanisms, however, can allow continued proliferation despite the presence of dysfunctional telomeres. Under such conditions, high levels of genome instability are often engendered. Data from both mouse and human model systems indicate that a period of genome instability might facilitate tumorigenesis. The high-density SNP-based microarrays (e.g., Affymetrix 100K arrays) can detect deletions, amplifications, and loss-of-heterozygosity on a genome in the liposarcoma samples. Chromosomal alterations of liposarcoma should provide insight into the molecular pathways involved in the regulation of ALT and reveal several loci that might be exploited either as prognostic markers or targets of chemotherapeutic intervention. Quality control steps taken: a. PCR-based quality assessment of liposarcoma tissue genomic DNA b. Nanodrop analysis of preprocessed DNA prior to array hybridization c. Analysis of array call rates following hybridization (array experiments giving call rates of less than 80% were routinely repeated) Data extraction and processing protocols a. Image scanning hardware and software, and processing procedures and parameters: SNP array hybridization was detected using a GCS3000 scanner (Affymetrix). SNP calls and signal quantification were obtained with Gene Chip Operating System (GCOS) 1.2 and Affymetrix GDAS 3.0 with Dynamic Model Mapping Analysis by default settings (0.25) for both homozygote and heterozygote call thresholds. Copy number analyses were carried out using Affymetrix Chromosome Copy Number Analysis Tool (CNAT) 2.1 with a default genomic smoothing window setting of 0.5 Mb. b. Normalization, transformation and data selection procedures and parameters. Array data was normalized by a reference data set with CNAT. c. Definition of chromosomal aberration, amplification, deletion and LOH used for data interpretation: These definitions and their algorithms were described in detail by Huang, et al: Whole genome DNA copy number changes identified by high density oligonucleotide arrays. Hum Genomics. 2004 May;1(4):287-99.