Purpose: Transforming growth factor β1 (TGF-β1) inhibits the growth of bladder cancer cells and this effect is prominent and constant in 253J bladder cancer cells. We performed a microarray analysis to search for genes that were altered after TGF-β1 treatment to understand the growth inhibitory action of TGF-β1.
Materials and methods: 253J bladder cancer cells were exposed to TGF-β1 and total RNA was extracted at 6, 24, and 48 hours after exposure. The RNA was hybridized onto a human 22K oligonucleotide microarray and the data were analyzed by using GeneSpring 7.1.
Results: In the microarray analysis, a total of 1,974 genes showing changes of more than 2.0 fold were selected. The selected genes were further subdivided into five highly cohesive clusters with high probability according to the time-dependent expression pattern. A total of 310 genes showing changes of more than 2.0 fold in repeated arrays were identified by use of simple t-tests. Of these genes, those having a known function were listed according to clusters. Microarray analysis showed increased expression of molecules known to be related to Smad-dependent signal transduction, such as SARA and Smad4, and also those known to be related to the mitogen-activated protein kinase (MAPK) pathway, such as MAPKK1 and MAPKK4.
Conclusions: A list of genes showing significantly altered expression profiles after TGF-β1 treatment was made according to five highly cohesive clusters. The data suggest that the growth inhibitory effect of TGF-β1 in bladder cancer may occur through the Smad-dependent pathway, possibly via activation of the extracellular signal-related kinase 1 and Jun amino-terminal kinases Mitogen-activated protein kinase pathway.
Keywords: Cell line; Gene expression; Microarray analysis; Transforming growth factor beta; Urinary bladder neoplasms.