A new strategy for protein biomarker discovery utilizing 2-nitrobenzenesulfenyl (NBS) reagent and its applications to clinical samples

For the purpose of biomarker discovery, we originally developed a novel method for quantitative proteome analysis utilizing both tryptophan-targeted stable isotope tagging and mass spectrometry. The method has now been refined by replacing detergents and an enrichment column and further utilizing a novel matrix that is specifically suitable for tagged peptides. A total analytical system has been constructed by combining this method with HPLC, an automatic spotter, MALDI-TOF MS and analytical software. Clinical tissue samples such as colorectal carcinoma and renal cell carcinoma were analyzed using this system, and the results demonstrated that it is useful for discovering novel biomarker candidates. Here, we review a series of these studies and also discuss future directions for development of this technology.