Prostate is a unique organ that produces and releases large amounts of
citrate. This is reduced significantly in
cancer and it is possible that
citrate is (re)taken up and used as a metabolite to enhance cellular activity. The main purpose of this study was to determine how cytosolic
citrate might affect in vitro metastatic cell behaviours (lateral motility, endocytosis and adhesion). Normal (PNT2-C2) and metastatic (PC-3M) human
prostate cancer cells were used in a comparative approach. As regards intermediary metabolic
enzymes,
aconitase and
fatty acid synthase, already implicated in
prostate cancer, were evaluated. The level of intracellular
citrate was significantly higher in PNT2-C2 cells under both control conditions and following preincubation in extracellular
citrate. Supply of exogenous
citrate enhanced endocytosis, lateral motility, decreased cell adhesion of PC-3M cells but failed to produce any effect on normal cells. Real-time PCR measurements showed that the
mRNA levels of mitochondrial and cytosolic aconitases and
fatty acid synthase were significantly higher in PC-3M cells. Correspondingly,
aconitase activity was also higher in PC-3M cells. Using
cerulenin (an inhibitor of
fatty acid synthase),
oxalomalate and
fluorocitrate (inhibiting aconitases), we investigated the dependence of
citrate-induced down-regulation of cellular adhesion on
aconitase and
fatty acid synthase activities. It was concluded: (1) that strongly metastatic PC-3M cells stored less/utilised more cytosolic
citrate than the normal PNT2-C2 cells and (2) that
cancer cells could metabolise cytoplasmic
citrate via
aconitase and
fatty acid synthase to enhance their metastatic behaviour.