Prostate epithelial cells utilize glucose and aspartate as the carbon sources for net citrate production

The prostate gland (human, rat ventral prostate) has the major function of accumulating and secreting extremely high levels of citrate. This function requires unique and specialized metabolic pathways associated with prostate secretory epithelial cells by which exogenous substrates must be utilized as the six-carbon sources of citrate. Recent studies demonstrated that aspartate can serve as the four-carbon source of oxalacetate for citrate synthesis. Identification of the two-carbon source of acetyl CoA (AcCoA) had not been established. The present study investigated the probability that exogenous glucose, via pyruvate oxidation, is a physiological source of AcCoA for net citrate production by isolated epithelial cells from rat ventral prostate. Under adequate oxygenation, 5 mM glucose in the presence of aspartate plus glutamate markedly stimulated citrate production. Exogenous and endogenous pyruvate also stimulated net citrate production. We propose that glucose via aerobic glycolysis and pyruvate oxidation provides AcCoA, which condenses with oxalacetate obtained from aspartate transamination for citrate synthesis. Prostate epithelial cells do not readily oxidize citrate, which permits accumulation and secretion of the synthesized citrate.