Protein expression profiling in chemical carcinogenesis: a proteomic-based approach

The simultaneous analysis of a wide array of proteins may provide valuable information on the activation and suppression of cellular systems at different stages of the exposure-disease continuum. In this review, results of proteomic studies in the field of toxicology are covered, focusing on the effects of chemical carcinogens. So far, alterations of highly abundant proteins have been identified which, irrespective of the wide differences in study design and technologies used, can be grossly assigned to three functional classes: proteins related to cellular stress response, inflammation, and stimulation of the immune system. It is obvious that the observed protein alterations are not causal factors in the development of chemically induced cancer but rather reflect common reactions to cellular perturbations. In order to gain deeper insights into the process of chemical carcinogenesis, the previously applied "shotgun" analyses have to be abandoned in favour of targeted proteomic approaches focusing on the accurate identification and quantification of selected proteins. Advanced analytical techniques such as selective reaction monitoring (SRM) and multiple reaction monitoring (MRM) offer this opportunity. If toxicoproteomic research moves into that direction and takes advantage of such techniques it will have the potential to contribute to the elucidation of chemical carcinogenesis.