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Zinc blocks gene expression of mitochondrial aconitase in human prostatic carcinoma cells
Author(s) -
Tsui KeHung,
Chang PheiLang,
Juang HorngHeng
Publication year - 2005
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.21411
Subject(s) - aconitase , gene expression , zinc , enzyme , gene , mitochondrion , biology , in vitro , intracellular , microbiology and biotechnology , regulation of gene expression , chemistry , biochemistry , cancer research , organic chemistry
Mitochondrial aconitase (mACON) contains a [4Fe‐4S] cluster as the key enzyme for citrate oxidation in the human prostatic epithelial cell. Although there is accumulating evidence indicating that accumulation of high levels of zinc in prostate epithelial cells causes reduced efficiency of citrate oxidation, zinc regulation on the mACON is still not well understood. From in vitro studies, zinc chloride treatment has been developed using humic acid as the carrier (Zn‐HA) in human prostatic carcinoma cells, PC‐3. Zn‐HA treatment (0.1–10 μM) restricts mACON enzymatic activity, which attenuates citrate utility and decreases intracellular ATP levels in PC‐3 cells, whereas the effect is blocked by adding the zinc chelator, diethylenetriaminepentaacetic acid (DTPA). Immunoblot, ribonuclease‐protection and transient gene‐expression assays indicate that Zn‐HA treatments inhibit mACON gene expression. Mutation of the putative metal response element (MRE) from CTCGCCTTCA to TGATCCTTCA abolishes Zn‐HA inhibition of mACON promoter activity. Our results have demonstrated that zinc possesses a specific regulatory mechanism on the mACON gene, and a biologic function of the putative metal regulatory system in mACON gene transcription has been identified. © 2005 Wiley‐Liss, Inc.