Identification of differentially expressed proteins using MALDI-TOF mass spectra

In the search for diagnostic and therapeutic strategies for lung cancer, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been evinced as a new and promising discovery platform to generate protein expression profiles in search of overexpressed proteins in lung tumors. Data from MALDI-TOF spectra require considerable signal processing such as noise removal and baseline level error correction. In this study, we discuss our preliminary approaches to these issues. We further present a novel algorithm that identified two proteins that are differentially expressed between tumor and normal tissues in patients with lung cancer. The overexpression of these two proteins was confirmed by immunoblotting, and their localization to tumor cells was studied by immunohistochemistry. Our results indicate that the proposed schemes enable accurate diagnosis based on the overexpression of a small number of identified proteins with high sensitivity, suggesting that these proteins would be helpful in further study of drug design.