title: Manganese antagonizes iron blocking mitochondrial aconitase expression in human prostate carcinoma cells.
abstract: OBJECTIVE
  To investigate the possible role of manganese in the regulation of mitochondrial aconitase (mACON) activity human prostate carcinoma cell line PC-3 cells.
  
  
  METHODS
  The mACON enzymatic activities of human prostate carcinoma cell line PC-3 cells were determined using a reduced nicotinamide adenine dinucleotide-coupled assay. Immunoblot and transient gene expression assays were used to study gene expression of the mACON. The putative response element for gene expression was identified using reporter assays with site-directed mutagenesis and electrophoretic mobility-shift assays.
  
  
  RESULTS
  In vitro study revealed that manganese chloride (MnCl2) treatment for 16 h inhibited the enzymatic activity of mACON, which induced the inhibition of citrate utility and cell proliferation of PC-3 cells. Although results from transient gene expression assays showed that MnCl2 treatment upregulated gene translation by approximately 5-fold through the iron response element pathway, immunoblot and reporter assays showed that MnCl2 treatments inhibited protein and gene expression of mACON. This effect was reversed by co-treatment with ferric ammonium citrate. Additional reporter assays with site-directed mutagenesis and electrophoretic mobility-shift assays suggested that a putative metal response element in the promoter of the mACON gene was involved in the regulation of MnCl2 on the gene expression of mACON.
  
  
  CONCLUSIONS
  These findings suggest that manganese acts as an antagonist of iron, disrupting the enzymatic activity and gene expression of mACON and citrate metabolism in the prostate.
authors.affiliation: Department of Anatomy, Chang Gung University, 259 Wen-Hua 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan, China.
authors.forename: Ke-Hung
authors.initials: KH
authors.lastname: Tsui
authors.forename: Phei-Lang
authors.initials: PL
authors.lastname: Chang
authors.forename: Horng-Heng
authors.initials: HH
authors.lastname: Juang
mesh_terms: D000154:Aconitate Hydratase / Q000037:antagonists & inhibitors / Q000235:genetics*; D000199:Actins / Q000235:genetics; D000255:Adenosine Triphosphate / Q000378:metabolism; D045744:Cell Line, Tumor; D002712:Chlorides / Q000494:pharmacology*; D002951:Citrates / Q000378:metabolism; D017931:DNA Primers; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D017930:Genes, Reporter; D006801:Humans; D007501:Iron / Q000378:metabolism*; D008297:Male; D017895:Manganese Compounds / Q000494:pharmacology*; D008928:Mitochondria / Q000201:enzymology*; D011471:Prostatic Neoplasms / Q000201:enzymology
chemical_list: D000199:Actins; D002712:Chlorides; D002951:Citrates; D017931:DNA Primers; D017895:Manganese Compounds; D000255:Adenosine Triphosphate; D007501:Iron; D000154:Aconitate Hydratase; C025340:manganese chloride