Chiparray basierte Identifikation von differentiell expremierten Genen beim kolorektalen Karzinom nach Laser-gestützter Mikrodissektion

Abstract

Differential gene expression as a result of molocular alterations in cancer play an important role for defining new diagnostic biomarkers and treatment targets. Chiparray technology enabling expression analysis of thousands of genes simultaneously has already been successfully applied for the identification of differentially expressed genes (DEGs) in several tumor entities. The aim of this study was to identify DEGs in colorectal cancer by comparing chiparray-based expressiondata from normal and corresponding cancerous epithelium after laser microdissection. We used Affymetrix GeneChips to monitor the gene expression of about 33.000 known genes in 25 patients with colorectal cancer. By generating a rank for all detected genes based on statistical tests 2352 genes and expressed sequence tags (ESTs) were identified to be differentially expressed. Besides several DEGs which were already known to be associated with colorectal cancer or other tumor entities, genes like carbonic anhydrase IV, fatty acid binding protein 1 and hevin were found to be differentially downregulated whereas genes like melanoma growth stimulating activity (Onkogen), S-adenosylcystein-hydrolase, general transcription factor IIIa and transforming growth factor showed a significant upregulated expression in tumor. Validation of selected genes on RNA and protein-level showed good reproducibility. Whether the identified DEGs and ESTs presented in this study encode new potential tumor markers or potential novel therapeutic targets in colorectal cancer has to be further evaluated.