Oncoproteomic approaches to cancer marker discovery: The case of colorectal cancer

Abstract

Colorectal cancer (CRC) is one of the most common types of cancer; it is diagnosed in more than one million people each year and causes the death of about half of them. Early detection can help to decrease CRC-related mortality. In fact, the 5-year survival rate exceeds 90% when the disease is localized and is only 10% in case of metastases. Consequently, it is imperative to improve methods for the early detection of the disease. In this context, genomic approaches have resulted in new CRC biomarkers and have helped to shed light on the genetic basis of cancer as a whole. However, the proteome provides a more dynamic and faithful image of the genetic program of a cell. Hence, given the importance of proteins as effectors of cellular behavior, proteomic analysis has the potential to identify biomarkers that can help to classify and predict CRC. Several proteomic technique, such as matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), quantitative isotopic protein labeling (SILAC, ICAT, and iTRAQ), and two-dimensional gel electrophoresis (2D-PAGE and 2D-DIGE), are being used in cancer research and can improve the diagnosis of patients; they are also helping to optimize personalized therapy. In this chapter, the main proteomic approaches used in biomarker research will be discussed, together with their impact and potential in the clinical setting. The proteomic biomarkers currently used for CRC diagnosis and/or therapy monitoring will be also described.