Development of glycosylation based cancer therapies using metabolic oligosaccharide engineering

Glycosylation;Metbolic Oligosaccharide Engineering;Endocytosis;Internalisation;Pancreatic Cancer;Biomedical Engineering

Mathew, Mohit PhilipBetenbaugh, Michael J. ;

Johns Hopkins University

关键词: Glycosylation;    Metbolic Oligosaccharide Engineering;    Endocytosis;    Internalisation;    Pancreatic Cancer;    Biomedical Engineering;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/40259/MATHEW-DISSERTATION-2016.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Abnormal glycosylation is a universal feature of cancer; however, in the past these changes have been viewed as passive by products of abnormal metabolism with efforts largely being directed at using these characteristic abnormalities as biomarkers for cancer detection. More recently glycosylation has been shown to play a number of crucial roles in the activity and localization of proteins and in the overall behavior of cells. While cancer related glycosylation abnormalities may have a metabolic origin, they likely play a much larger role in the maturation of the disease phenotype and in its eventual progression. In order to study changes in glycosylation, alterations in the glycan patterns need to be made this can either be done by genetic manipulation of the glycosylation machinery or by altering fluxes through the pathway via metabolic oligosaccharide engineering. One of the major advantages of using a flux based approach is that it can make use of pharmacologically relevant small molecules that are easier to use than genetic means. However a significant roadblock to use to metabolic oligosaccharide engineering is the low uptake efficiency of sugar molecules, this is overcome by the use of short chain acid (SCFA) linked sugar molecules. The addition of these SCFA groups converts these molecules into a unique form of prodrug in that they need to resist esterase processing outside the cell and require intracellular esterase processing to release the core sugar. The first part of this thesis characterizes the esterase processing of these sugar analog prodrugs. The analogs were found to be fairly resistant to extracellular inactivation surviving for between 2 and 4 h in 100% fetal bovine serum. In comparison intracellular processing was shown to be much faster, interestingly there appeared to be an activation of the intracellular esterases by analog treatments. Investigation of thisiiicrosstalk revealed that increased sialylation of carboxyl esterases led to a stabilization of more active trimeric and hexameric forms of this enzyme. The next portion of the study used metabolic oligosaccharide engineering as a tool to alter glycosylation and the epidermal growth factor receptor’s sialylation is observed to increase. The effect of increased sialylation on the epidermal growth factor receptor (EGFR) is investigated and shown to lead to an inhibition of EGFR signaling. This understanding of the functional significance of altered glycosylation is then translated towards clinical end points with 1,3,4-O-Bu3ManNAc shown to have remarkable synergy when used in conjunction with EGFR targeting drugs Erlotinib and Gefitinib. Finally, the underlying molecular mechanism by which this analog induced change in glycosylation affects receptor signaling is characterized. Increased sialylation caused by analog treatment was found to disrupt the galectin lattice which led to an increase in non clathrin mediated endocytosis wherein the resulting endosomes are fated primarily for degradation, this leads to a decrease in EGFR surface localization and increased signal attenuation.