Proteomic differentiation between disease-induced changes in expression and post-translational modifications
Abstract
Aberrations in protein glycosylation are a common phenotype in cancer. These cancer-associated glycans can alter the function of tumor cells, their antigenic and adhesive properties, and their potential to metastasize and invade remote tissues. The work reported here describes the development of methods that affinity select, identify, and quantify glycoproteins shed into blood that are linked to cancer. The relationship between increases in aberrant glycan structures on glycoproteins and cancer progression has led to the effort to define various types of cancer in terms of quantitative signatures of glycoprotein isoforms. Quantification is complicated by the presence of multiple gylcoforms and difficulty in differentiating between them. The Lewis antigens are one of the most widely known glycans associated with cancer. Through the use of antibodies targeting these antigens, specific glycoproteins bearing Lewis antigens were selected from plasma by immunoaffinity chromatography. Following trypsin digestion, peptide cleavage fragments were separated by reverse-phase chromatography and identified by tandem mass spectrometry. Based on the sequence of these peptides, glycoproteins in samples were alternatively selected and quantified. Comparing results from these two approaches allows differentiation between changes in expression and altered post-translational modifications among control subjects and breast cancer patients.
Degree
Ph.D.
Advisors
Regnier, Purdue University.
Subject Area
Analytical chemistry
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