Robert B. Campbell
John Gatley, Wan Kai-Tak
Date of Award
Master of Science
Department or Academic Unit
Bouvé College of Health Sciences. Department of Pharmaceutical Sciences.
pharmacy, health sciences, diffusion barrier, drug barrier, Glycosylation, Mucin, Mucin and Chemotherapy, Mucin and Pancreatic cancer
Drug delivery systems, Cancer--Treatment, Mucins--Analysis
Pharmacy and Pharmaceutical Sciences
Mucins are heavily glycosylated glycoproteins that form a thick layer (glycocalyx) through which all molecules must diffuse to gain access to intracellular targets. They are overexpressed in cancerous conditions and have been implicated in invasion and metastasis of variety of tumors. Over 85% of human cancers are solid tumors in which the effectiveness of cancer therapy depends on adequate delivery of the therapeutic agent to tumor cells. Inadequate delivery would result in residual tumor cells, which in turn could lead to the re growth of tumors and the development of resistant cells. It has recently been shown that pre-exposing human pancreatic cancer cells to glycosylation inhibitors significantly enhances the cytotoxic effects of 5-FU against those cells. Further investigation of this observation led to the conclusion that O-glycosyaltion inhibition of mucin is responsible for the enhanced cytotoxic effects of 5-FU. In this study we explore the role N-glycosylation of mucin (second predominant glycosylation after type O), alone and in combination with O-glycosylation, in the cytotoxic effects of 5-FU in vitro. The study also aims to correlate the effects of inhibiting mucin glycosylation with the intracellular concentration of the cytotoxic prodrug 5-FU and its most active metabolites.
Cytotoxicity was determined by SRB assay while the intracellular concentration of 5-FU was determined by radiometric drug detection and analysis. Inhibition of mucin O-glycosylation increased the cytotoxicity of 5-FU significantly. This was positively correlated to the concentration of 5-FU and its metabolites intracellularly. Inhibition of N-glycosylation did not show any significant increase in cytotoxicity of 5-FU. Inhibition of both O- and N- glycosylaiton did not show any significant benefit when compared to the inhibiton of O- glycosylation alone. In summary, the inhibition of type O-glycosylation of mucin was sufficient to achieve maximum cytotoxic drug effects, and the inhibition of N-glycosylation did not improve on the benefits of inhibiting type O-glycosylaiton alone. Furthermore, the intracellular drug concentrations are generally consistent with the observed cytotoxic drug effects involving the use of human mucin expressing cancer cell lines.
Aalok A. Shah
Shah, Aalok A., "Evaluation of Mucin Glycosylation as a barrier to drug uptake : a quantitative approach" (2009). Pharmaceutical Science Master's Theses. Paper 13. http://hdl.handle.net/2047/d20000236
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