Gene expression profiling of chemically induced rat bladder tumors.

A variety of genetic alterations and gene expression changes are involved in the pathogenesis of bladder tumors. To explore expression changes in 4-hydroxybutyl(butyl)nitrosamine-induced rat bladder tumors, microarray analysis was performed. Analysis yielded 1,138 known genes and 867 expressed sequence tags that were changed when comparing tumors to normal rat epithelia. Altered genes included cell cycle-related genes, EGFR-Ras signaling genes, apoptosis genes, growth factors, and oncogenes. Using the pathway visualization tool GenMAPP, we found that these genes can be grouped along several pathways that control apoptosis, cell cycle, and integrin-mediated cell adhesion. When comparing current data with previous mouse bladder tumor data, we found that > 280 of the same known genes were differentially expressed in both mouse and rat bladder tumors, including cell cycle-related genes, small G proteins, apoptosis genes, oncogenes, tumor-suppressor genes, and growth factors. These results suggest that multiple pathways are involved in rat bladder tumorigenesis, and a common molecular mechanism was found in both rat and mouse bladder tumors.