Proteomic Profiling of Human Colorectal Carcinoma using the NBS Method

Abstract

In the development of novel biomarkers, the proteomic approach is advantageous because it can directly identify cancer-associated proteins. We previously developed a 2-nitrobenzenesulfenyl (NBS) method to improve quantitative proteome analysis. Here, we applied this method to proteomic profiling of colorectal carcinoma (CRC) to identify novel proteins with altered expression in CRC. Each pair of tumor and normal tissue specimens from 12 CRC patients was analyzed, and approximately 5000 NBS-labeled paired peaks were quantified. Peaks with altered signal intensities (> 1.5-fold) and that occurred frequently in samples (> 70%) were selected, and 128 proteins were identified by MS/MS analyses as differentially expressed proteins in CRC tissues. Many proteins were newly revealed to be CRC-related; 30 were reported in earlier studies of CRC. Six proteins (ZYX, RAN, RCN1, AHCY, LGALS1, and VIM) that were up-regulated in CRC were further characterized and validated by western blot and immunohistochemistry. All six were found to be CRC-localized, either in cancer cells or in stroma cells near the cancer cells. These results indicate that the proteins identified in this study are novel candidates for CRC markers, and that the NBS method is useful in proteome mining to discover novel biomarkers.