Exon level expression profiling of colorectal cancer tissue samples (test sample series).

Colorectal cancer is a heterogeneous disease molecularly characterized by inherent genomic instabilities, chromosome instability and microsatellite instability. In the present study we propose transcriptome instability as an analogue to genomic instability on the transcriptome level. Exon microarray data from two independent series of altoghether 160 colorectal cancer tissue samples was used for global alternative splicing detection using the FIRMA algorithm (aroma.affymetrix). The sample-wise amounts of these alternative splicing scores exceeding a defined threshold (deviating exon usage amounts) were summarized to provide the basis for description of transcriptome instability. This characteristic was shown to be associated with splicing factor expression levels and patient survival in both independent sample series.

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Sveen A, Agesen TH, Nesbakken A, Rognum TO, Lothe RA, Skotheim RI