Dissertation
O-GlcNAcylation regulates pancreatic cancer cell survival and NF-[kappa]B signaling
Doctor of Philosophy (Ph.D.), Drexel University
21 Nov 2013
DOI:
https://doi.org/10.17918/00010143
Abstract
Cancer cell metabolic reprogramming includes a shift in energy production from oxidative phosphorylation to less efficient glycolysis even in the presence of oxygen (Warburg effect) and use of glutamine for increased biosynthetic needs. This necessitates greatly increased glucose and glutamine uptake, both of which enter the hexosamine biosynthetic pathway (HBP). The HBP end product UDP-N-acetylglucosamine (UDP-GlcNAc) is used in enzymatic post-translational modification of many cytosolic and nuclear proteins by O-linked [beta]-N-acetylglucosamine (O-GlcNAc). Increased HBP flux in diabetes has been linked to increased levels of O-GlcNAcylation. This led us to hypothesize that cancer metabolic reprogramming may drive increased levels of O-GlcNAcylation. In this study, we observed increased HBP flux and hyper-O-GlcNAcylation in human pancreatic ductal adenocarcinoma (PDAC). PDAC hyper-O-GlcNAcylation was associated with elevation of OGT and reduction of the enzyme that removes O-GlcNAc (OGA). Reducing hyper-O-GlcNAcylation had no effect on non-transformed pancreatic epithelial cell growth, but inhibited PDAC cell proliferation, anchorage-independent growth, orthotopic tumor growth, and triggered apoptosis. PDAC is supported by oncogenic NF-[kappa]B transcriptional activity. The NF-[kappa]B p65 subunit and upstream kinases IKK[alpha]/IKK[beta] were O-GlcNAcylated in PDAC. Reducing hyper-O-GlcNAcylation decreased PDAC cell p65 activating phosphorylation (S536), nuclear translocation, NF-[kappa]B transcriptional activity, and target gene expression. Conversely, mimicking PDAC hyper-O-GlcNAcylation through pharmacological inhibition of OGA suppressed suspension culture-induced apoptosis and increased IKK[alpha] and p65 O-GlcNAcylation, accompanied by activation of NF-[kappa]B signaling. Furthermore, we mapped O-GlcNAcylation of p65 at T305, S319, 5337, T352, and S374. O-GlcNAcylation of p65 at T305 increased CBP/p300-dependent activating acetylation of p65 at K310, contributing to NF-[kappa]B transcriptional activation. In addition, elevation of O-GlcNAcylation by overexpression of OGT increased the expression of p300, IKK[alpha] and IKK[beta] and promoted IKK-mediated activating phosphorylation of p65 at S536, contributing to NF-[kappa]B activation. Our data indicate that pancreatic cancer exhibits hyper-O-GlcNAcylation and that hyper-O-GlcNAcylation is anti-apoptotic and through interplay with phosphorylation and acetylation contributes to NF-[kappa]B oncogenic activation in PDAC.
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Details
- Title
- O-GlcNAcylation regulates pancreatic cancer cell survival and NF-[kappa]B signaling
- Creators
- Zhiyuan Ma
- Contributors
- Keith Vosseller (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xii, 188 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology; College of Medicine; Drexel University
- Other Identifier
- 991021888825404721