Date on Master's Thesis/Doctoral Dissertation

12-2014

Document Type

Master's Thesis

Degree Name

M.S.

Department

Biochemistry and Molecular Biology

Committee Chair

Telang, Sucheta

Committee Co-Chair (if applicable)

Ellis, Steven

Committee Member

Clark, Barbara J.

Abstract

Altered energy metabolism is an established hallmark of cancer cells. Fructose-2,6-bisphosphate is an allosteric activator of glycolysis and its concentration in a cell is dictated by the 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatases (PFKFB1-4) family of bifunctional enzymes. The PFKFB family of enzymes are characterized by their different kinase: bisphosphatase activities and were originally determined to be tissue-specific. More recent data however suggest that multiple isoforms are co-expressed in both normal and neoplastic tissues. PFKFB4 is highly expressed in human cancer, strongly induced by hypoxia, and required for the survival of cancer cells. However, it remains unclear whether the kinase or phosphatase activity of human PFKFB4 dominates. In this study, we developed a method of synthesizing and purifying human recombinant PFKFB4 and, using this purified protein, found that PFKFB4 has a kinase to phosphatase ratio of 4.1:1. We found that a novel small molecule inhibitor of PFKFB4 (5MPN) inhibited the kinase activity of PFKFB4 and further that the known PFKFB3 inhibitors (PFK15 and PFK158) inhibited PFKFB4 less efficiently than 5MPN. We conclude that PFKFB4 functions mainly as a kinase and that, given the co-expression of PFKFB3 and PFKFB4, targeting both PFKFB3 and PFKFB4 isoforms using PFK158 and 5MPN may be a useful treatment option in cancer.

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