|dc.description.abstract||Cancer cells have the ability to survive when oxygen is limiting, and upregulate
the pathway of fatty acid synthesis, owing in part to alterations in their metabolism. I
compared the metabolic phenotypes of the prostate cancer cell lines LNCaP, DU145, and
PC3 assessing energy metabolism, and metabolic gene expression. I also explored the
plasticity of the metabolic phenotype following passage, selection and in vivo growth.
Finally, I explored the sensitivity of the fatty acid synthesis pathway to low oxygen.
LNCaP cells had a more oxidative phenotype based on oxygen consumption,
lactate production, enzyme assays, and mRNA levels. While DU145 and PC3 cells were
more glycolytic, they were unresponsive to dichloroacetate (DCA), and dinitrophenol
(DNP), stimulators of oxygen consumption. Mitochondrial dysfunction in the PC3 and
DU145 cells may explain this phenomenon, for they possessed normal cardiolipin levels
but lower mitochondrial enzyme activities (cytochrome oxidase (COX), citrate synthase
When LNCaP cells were subjected to high passage, with and without clonal
selection, the derived lines acquired a dysfunctional oxidative phenotype, becoming more
glycolytic. Clonal selection appeared to have the most dramatic effect on cellular
metabolism. This finding is supported by decreased oxygen consumption, increased
lactate production, and a reduction in the activity of the oxidative enzymes CS and COX
in the clonally selected LNCaP-luc cell line. Similar to the DU145 and PC3 cells, NAO
fluorescence indicates that the oxidative impairment in these LNCaP-derived lines may
be due to a reduction in mitochondrial activity. The pattern of metabolic gene expression
seen in vitro was unaffected when LNCaP cells were grown as subcaspular and muscle
xenografts in immunodeficient mice, though xenografts did exhibit indications of an
hypoxic response (elevated VEGF mRNA).
Oxygen deprivation in vitro increased mRNA for HIF and responsive genes but
not SREBP responsive genes. Similarly, oxygen deprivation had no influence on
triglyceride levels in any of the lines suggesting that the SREBP axis may not be directly
modulated by oxygen levels.
Collectively these studies demonstrate differences in the metabolism of these
prostate cancer models, with important ramifications of therapeutic strategies involving