Protein expression in the livers and urinary bladders of hamsters exposed to sodium arsenite

Hamsters were exposed to sodium arsenite (173 mg As/L) in drinking water for 6 days and control hamsters were given tap water. Equal amounts of protein from the urinary bladder or liver extracts of control and arsenic-treated hamsters were labeled with Cy3 and Cy5 dyes, respectively. The labeled proteins were mixed and separated in the two-dimensional differential in gel electrophoresis (2D-DIGE). After DIGE and analysis by the DeCyder software, several protein spots were found to be overexpressed and several were underexpressed. Analysis of the DIGE gel images detected 75 protein spots in the livers and 52 protein spots in the urinary bladders of hamsters that were expressed (+/-1.2-fold). Of the detected protein spots, 34 spots were overexpressed (1.48 +/- 0.05) and 41 spots were underexpressed (1.52 +/- 0.06) in the liver. In the urinary bladder, 36 protein spots were overexpressed (1.52 +/- 0.06) and 16 protein spots were underexpressed (1.39 +/- 0.05). Three proteins (one was overexpressed and two were underexpressed) of each tissue (liver or bladder) were identified by mass spectrometry. DIGE in combination with mass spectrometry is a powerful tool that may be of help in understanding the molecular mechanisms of cancer progression due to inorganic arsenic.