Differential expression of proteins in rat plasma exposed to benzene

Benzene, a ubiquitous environmental contaminant, is an important solvent in the chemical industry and is also known as a constituent of petroleum. It has been reported that benzene is associated with hematotoxicity including leukemia in humans and cancer in laboratory animals. To study protein expression alterations in rat plasma exposed to benzene, rats were exposed to levels of 1, 10, 100 ppm benzine for 6 h/day and 5 d/week for 2 or 6 weeks. Two-dimensional gel electrophoresis of rat plasma was carried out, and approximately 1000 protein spots were detected on the gels. The 11 spots which showed significantly different expression were selected and identified with matrix-assisted laser desorption/ionization-time of flight-mass spectrometry. Analyzing the targeted 11 spots, there was no correlation between the 2 and 6 weeks benzene-inhaled groups on up-regulated proteins (zinc finger protein, and tristetraprolin) and on down-regulated proteins (cAMP-regulated guanine nucleotide exchange factor II, protein kinase and unknown protein). The overexpressed proteins (inhibitor of kappaB-like protein, GTP-binding protein rab14, T-cell receptor alpha chain, and somatostatin transactivating factor-1) were detected only in groups inhaling benzene for 6 weeks. Among them the expression level of T-cell receptor alpha chain was confirmed by Western blot.