Tsui Ke-Hung, Chang Phei-Lang, Juang Horng-Heng
Department of Urology, Chang Gung Memorial Hospital, Kwei-Shan, Taiwan, Republic of China.
Int J Cancer. 2006 Feb 1;118(3):609-15. doi: 10.1002/ijc.21411.
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 microM) 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.
线粒体乌头酸酶（mACON）含有一个[4Fe-4S]簇，是人类前列腺上皮细胞中柠檬酸氧化的关键酶。尽管越来越多的证据表明前列腺上皮细胞中高水平锌的积累会导致柠檬酸氧化效率降低，但锌对mACON的调节仍未完全了解。在体外研究中，已开发出在人前列腺癌细胞PC-3中使用腐殖酸作为载体的氯化锌处理方法（Zn-HA）。Zn-HA处理（0.1-10 microM）会限制mACON酶活性，这会减弱PC-3细胞中柠檬酸的利用并降低细胞内ATP水平，而添加锌螯合剂二乙烯三胺五乙酸（DTPA）可阻断该效应。免疫印迹、核糖核酸酶保护和瞬时基因表达分析表明，Zn-HA处理会抑制mACON基因表达。将假定的金属反应元件（MRE）从CTCGCCTTCA突变为TGATCCTTCA可消除Zn-HA对mACON启动子活性的抑制。我们的结果表明，锌对mACON基因具有特定的调节机制，并且已确定假定的金属调节系统在mACON基因转录中的生物学功能。
