Developing a Mass Spectrometry-based Workflow Targeting the Plasma Phosphoproteome for Cancer Biomarker Discovery

摘要

In many tumors and cancerous tissues, significant changes occur in protein phosphorylation that affect downstream signaling pathways and protein interaction networks. However, it remains unclear whether these cancer-related phosphoproteins can be observed in peripheral blood, where they might serve as potential early-stage biomarkers. Two very recent studies in plasma and serum suggest that this may indeed be possible (Zhou et al., 2009 J Proteome Res; Carrascal et al., 2010 J Proteome Res). To address this question in more detail, we developed a protocol whereby phosphatase inhibitors are added at a very early stage to platelet-depleted plasma to preserve the phosphorylation status of the plasma proteome and limit contamination from platelets and other cell types. Our overall aim in these early studies is to establish a list of plasma phosphoproteins using an optimized and robust workflow, identify their likely origin, and to begin to examine whether a subset of these phosphoproteins and/or specific phosphosites exist that may be unique to cancer-derived samples.