Characterizing pathways of lactate oxidation in cancer by using stable isotopes and metabolomics
Date of Award
Doctor of Philosophy (PhD)
It is well established that most cancer cells uptake increased amounts of glucose relative to normal differentiated cells. The majority of this glucose carbon is secreted from the cell as lactate. The fate of the remaining glucose carbon, however, has not been well characterized. Here we applied a novel combination of metabolomic technologies to track uniformly labeled glucose in HeLa cancer cells. We provide a list of specific intracellular metabolites that become enriched after 48 hours of labeling and quantitate the fraction of consumed glucose that ends up in proteins, peptides, sugars/glycerol, and lipids. Next, we investigated whether the main product of fermenting cells, lactate, has a different fate other than secretion. Here we explored the possibility that cytosolic lactate is metabolized by the mitochondria of fermenting mammalian cells. We found that fermenting HeLa and H460 cells utilize exogenous lactate carbon to synthesize a large percentage of their lipids. With high-resolution mass spectrometry, we found that both 13C and 2-2H labels from enriched lactate enter the mitochondria. The lactate dehydrogenase (LDH) inhibitor oxamate decreased respiration of isolated mitochondria incubated in lactate, but not isolated mitochondria incubated in pyruvate. Additionally, transmission electron microscopy (TEM) showed that LDHB localizes to the mitochondria. Taken together, our results demonstrate a link between lactate metabolism and the mitochondria of fermenting mammalian cells.
Chair and Committee
Gary J. Patti
Jacob Schaefer, Liviu Mirica, Richard Gross, Brian Finck
Chen, Ying-Jr Amanda, "Characterizing pathways of lactate oxidation in cancer by using stable isotopes and metabolomics" (2016). Arts & Sciences Electronic Theses and Dissertations. 835.
Available for download on Saturday, August 15, 2116
Permanent URL: https://doi.org/doi:10.7936/K7M61HN0