Hypoxia induces metabolic alteration in
cancer cells by stabilizing
hypoxia-inducible factor 1α (HIF-1α (HIF1A)), which regulates the bioenergetic genes of glycolysis and
lipid metabolic pathways. However, the target genes of
hypoxia-induced metabolic alterations in the prostate remain uncertain. Mitochondrial
aconitase (mACON) (ACONM) is an
enzyme that is central to
carbohydrate and energy metabolism and is responsible for the interconversion of
citrate to
isocitrate as part of the citric acid cycle in the human prostate. We evaluated the effects of the molecular mechanisms of
hypoxia on mACON gene expression in PC-3 and LNCaP human prostate
carcinoma cells. Immunoblotting assays revealed that
hypoxia modulated mACON and
lactate dehydrogenase A (LDHA)
protein expression, while these effects were attenuated when HIF-1α was knocked down.
Hypoxia induced
fatty acid synthase (FASN) in PC-3 cells while
hypoxia blocked FASN gene expression in LNCaP cells after 24-h incubation. Results of real-time RT-qPCR, immunoblotting, and transient gene expression assays revealed that
hypoxia treatment or co-transfection with HIF-1α expression vector enhanced gene expression of mACON, implying that
hypoxia modulated mACON at the transcriptional level.
Hypoxia-induced mACON promoter activity is dependent on the
DNA fragment located at -1013 to -842 upstream of the translation initiation site. l-
mimosine, an
iron chelator, stabilized HIF-1α but downregulated mACON gene expression, suggesting that
iron chelation blocked the
hypoxia-induced mACON gene expression. These results suggest that
hypoxia dysregulates the expressions of LDHA, FASN, and mACON genes, and the
hypoxia-induced mACON gene expression is via the HIF-1α-dependent and
iron-dependent pathways in prostate
carcinoma cells.