Colorectal cancer (CRC) is one of the most common cancers in the United States and the second ranked cause of cancer related death. This project proposes to perform both broad proteomic and glycomic screens and targeted analyses to discover early detection and diagnostic biomarkers of CRC. The goal is to improve colon screening by the addition of highly sensitive markers that together with each other or existing markers yield good specificity. We will interrogate unique prediagnostic plasma samples, tissue from primary CRC tumors, and plasma from CRC cases on custom high-density antibody microarrays (up to 6000 different analytes) to discover novel proteomic and glycomic biomarkers. Parallel arrays will be incubated with plasma or tissue lysate for proteomic comparison or glycosylation (via incubation with different lectins). This microarray approach employs technology with unparalleled sensitivity, enabling interrogation down to the low picomolar concentration of the circulating proteome. Biomarker candidates that pass the statistical threshold on a "discovery" array will be retained and be re-examined using new samples on smaller arrays (to reduce the false discovery rate) - a step we will refer to as "pre-validation" to indicate that a potential biomarker would have shown up as statistically significant in multiple sample sets but was not yet subjected to formal characterization or validation. This unique triage process allows for rapid sorting of potential biomarkers, allowing us to focus on only the most promising. The best candidates will then be evaluated with more conventional ELISA and lectin based methods. Our approaches will specifically target proteomic and glycomic changes in proteins critical for the regulation of apoptosis, proliferation, angiogenesis, inflammation/prostaglandins, insulin resistance, toll-like receptor (TLR), transforming growth factor (TGF)-? and STAT signaling pathway deregulation during CRC to discover biomarkers of early detection and diagnosis. These include over 300 phospho-specific antibodies and their matched non-phospho-specific counterparts to 21 MAPK, 12 TGF-?, and many STAT pathway targets.
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