University Department of Surgery, Royal Free Campus, UCL Medical School, London, UK.
Biometals. 2011 Feb;24(1):143-51. doi: 10.1007/s10534-010-9382-5. Epub 2010 Oct 19.
Trace elements are involved in many key pathways involving cell cycle control. The influence of zinc and zinc chelator (TPEN) on transcription levels of the main zinc transporters (ZnT1 and ZIP1) in the HT-29 colorectal cell line has not been reported. Proliferation of HT-29 cells was measured using the methylene blue assay after exposure to zinc (two concentrations), TPEN (two concentrations), or a combination of zinc and TPEN (simultaneously and sequentially) for 4 h, 8 h, and 24 h. The transcription levels of ZnT1, ZIP1, vascular endothelial growth factor (VEGF), and caspase-3 were determined using reverse transcriptase real-time polymerase chain reaction (RT-PCR) after exposure of cells to zinc and TPEN. The zinc content in the substrate (medium used for culture) was determined using atomic absorption spectrometry. TPEN decreased cellular proliferation causing complete cell death by 8 h. Zinc had a protective effect against short periods of exposure to TPEN. There was no correlation between the transcripts of main zinc transporters and the zinc content in the substrate. The zinc content in the substrate remained constant after varying periods of cell culture. TPEN decreased the transcript levels of caspase-3 and VEGF, which are surrogate markers for apoptosis and angiogenesis. Zinc chelation of HT-29 cells causes cell death. Zinc appears to be protective for short periods of exposure to TPEN but has no protective effect on prolonged exposure. HT-29 cells are not able to counteract the effect of intracellular chelation of zinc by altering zinc transport. Further research into the mechanisms of these findings is necessary and may lead to novel therapeutic options.
微量元素参与许多涉及细胞周期控制的关键途径。锌和锌螯合剂（TPEN）对 HT-29 结肠直肠细胞系中主要锌转运体（ZnT1 和 ZIP1）转录水平的影响尚未报道。用亚甲基蓝法测量 HT-29 细胞在暴露于锌（两种浓度）、TPEN（两种浓度）或锌和 TPEN（同时和顺序）4 小时、8 小时和 24 小时后的增殖情况。用逆转录实时聚合酶链反应（RT-PCR）测定细胞暴露于锌和 TPEN 后 ZnT1、ZIP1、血管内皮生长因子（VEGF）和 caspase-3 的转录水平。使用原子吸收光谱法测定基质（用于培养的培养基）中的锌含量。TPEN 降低细胞增殖，在 8 小时内导致完全细胞死亡。锌对 TPEN 的短期暴露具有保护作用。主要锌转运体的转录物与基质中的锌含量之间没有相关性。在不同的细胞培养期后，基质中的锌含量保持不变。TPEN 降低了 caspase-3 和 VEGF 的转录水平，它们是细胞凋亡和血管生成的替代标志物。HT-29 细胞中的锌螯合导致细胞死亡。锌在短时间暴露于 TPEN 时似乎具有保护作用，但对长时间暴露没有保护作用。HT-29 细胞无法通过改变锌转运来抵消细胞内锌螯合的作用。需要对这些发现的机制进行进一步研究，这可能会带来新的治疗选择。
