Recent advances in capillary electrophoresis-based proteomic techniques for biomarker discovery.

A compelling need exists for the development of technologies that facilitate and accelerate the discovery of novel protein biomarkers with therapeutic and diagnostic potential. The inherent disadvantage of biomarker dilution in complex biological fluids such as serum/plasma, urine, and saliva necessitates highly sensitive analytical approaches, often exceeding the dynamic range of currently available proteomic platforms. Thus, investigative studies directed at tissues obtained from the primary site of pathology probably afford the best opportunity for the discovery of disease biomarkers. This review therefore focuses on the most recent advances in capillary electrophoresis-based single and multidimensional separations coupled with ESI-MS for performing comprehensive and comparative analysis of protein expression profiles within clinical specimens. Advanced sample preparation techniques, including tissue microdissection, detergent-based membrane protein extraction, and heat-induced protein retrieval, further enable targeted protein profiling of both fresh-frozen, formalin-fixed, and paraffin-embedded tissues. Comparative proteomics involving measurements in changes of biological pathways or functional processes are expected to provide relevant disease-associated markers and networks, molecular relationships among different stages of disease, and molecular mechanisms that drive the progression of disease. From a practical perspective, the evaluation of comparative proteomic dataset within a biological context is essential for high-throughput data validation, prioritization of follow-on biomarker selection, and validation experiments.