Piberger Ann Liza, Keil Claudia, Platz Stefanie, Rohn Sascha, Hartwig Andrea
Food Chemistry and Toxicology, Institute of Applied Bioscience, Karlsruhe Institute of Technology, Karlsruhe, Germany.
Institute of Food Chemistry, Hamburg School of Food Science, University Hamburg, Hamburg, Germany.
Mol Nutr Food Res. 2015 Nov;59(11):2231-42. doi: 10.1002/mnfr.201500457. Epub 2015 Sep 23.
The isothiocyanate sulforaphane, a major breakdown product of the broccoli glucosinolate glucoraphanin, has frequently been proposed to exert anticarcinogenic properties. Potential underlying mechanisms include a zinc release from Kelch-like ECH-associated protein 1 followed by the induction of detoxifying enzymes. This suggests that sulforaphane may also interfere with other zinc-binding proteins, e.g. those essential for DNA repair. Therefore, we explored the impact of sulforaphane on poly (ADP-ribose)polymerase-1 (PARP-1), poly (ADP-ribosyl)ation (PARylation), and DNA single-strand break repair (SSBR) in cell culture.
Immunofluorescence analyses showed that sulforaphane diminished H2 O2 -induced PARylation in HeLa S3 cells starting from 15 μM despite increased lesion induction under these conditions. Subcellular experiments quantifying the damage-induced incorporation of (32) P-ADP-ribose by PARP-1 displayed no direct impact of sulforaphane itself, but cellular metabolites, namely the glutathione conjugates of sulforaphane and its interconversion product erucin, reduced PARP-1 activity concentration dependently. Interestingly, this sulforaphane metabolite-induced PARP-1 inhibition was prevented by thiol compounds. PARP-1 is a stimulating factor for DNA SSBR-rate and we further demonstrated that 25 μM sulforaphane also delayed the rejoining of H2 O2 -induced DNA strand breaks, although this might be partly due to increased lesion frequencies.
Sulforaphane interferes with damage-induced PARylation and SSBR, which implies a sulforaphane-dependent impairment of genomic stability.
异硫氰酸酯萝卜硫素是西兰花硫代葡萄糖苷葡萄糖萝卜硫苷的主要分解产物，人们经常认为它具有抗癌特性。潜在的潜在机制包括从类 Kelch 样 ECH 相关蛋白 1 释放锌，随后诱导解毒酶。这表明萝卜硫素也可能干扰其他锌结合蛋白，例如对 DNA 修复至关重要的那些蛋白。因此，我们在细胞培养中探讨了萝卜硫素对聚（ADP - 核糖）聚合酶 -1（PARP -1）、聚（ADP - 核糖基）化（PARylation）和 DNA 单链断裂修复（SSBR）的影响。
免疫荧光分析表明，尽管在这些条件下损伤诱导增加，但从 15 μM 开始，萝卜硫素可减少 H2O2 诱导的 HeLa S3 细胞中的 PARylation。通过 PARP -1 对损伤诱导的（32）P - ADP - 核糖掺入进行亚细胞实验显示，萝卜硫素本身没有直接影响，但细胞代谢产物，即萝卜硫素及其互变产物芥酸的谷胱甘肽共轭物，浓度依赖性地降低了 PARP -1 活性。有趣的是，硫醇化合物可阻止这种萝卜硫素代谢产物诱导的 PARP -1 抑制。PARP -1 是 DNA SSBR 速率的刺激因子，我们进一步证明，25 μM 萝卜硫素也延迟了 H2O2 诱导的 DNA 链断裂的重新连接，尽管这可能部分归因于损伤频率增加。
萝卜硫素干扰损伤诱导的 PARylation 和 SSBR，这意味着萝卜硫素依赖的基因组稳定性受损。
