Øverby Anders, Bævre Mette S, Thangstad Ole P, Bones Atle M
Department of Biology, Norwegian University of Science and Technology (NTNU) Trondheim, Norway.
Front Plant Sci. 2015 Jan 22;6:6. doi: 10.3389/fpls.2015.00006. eCollection 2015.
Isothiocyanates (ITCs) from biodegradation of glucosinolates comprise a group of electrophiles associated with growth-inhibitory effects in plant- and mammalian cells. The underlying modes of action of this feature are not fully understood. Clarifying this has involved mammalian cancer cells due to ITCs' chemopreventive potential. The binding of ITCs to tubulins has been reported as a mechanism by which ITCs induce cell cycle arrest and apoptosis. In the present study we demonstrate that ITCs disrupt microtubules in Arabidopsis thaliana contributing to the observed inhibited growth phenotype. We also confirmed this in rat bladder cancer cells (AY-27) suggesting that cells from plant and animals share mechanisms by which ITCs affect growth. Exposure of A. thaliana to vapor-phase of allyl ITC (AITC) inhibited growth and induced a concurrent bleaching of leaves in a dose-dependent manner. Transcriptional analysis was used to show an upregulation of heat shock-genes upon AITC-treatment. Transgenic A. thaliana expressing GFP-marked α-tubulin was employed to show a time- and dose-dependent disintegration of microtubules by AITC. Treatment of AY-27 with ITCs resulted in a time- and dose-dependent decrease of cell proliferation and G2/M-arrest. AY-27 transiently transfected to express GFP-tagged α-tubulin were treated with ITCs resulting in a loss of microtubular filaments and the subsequent formation of apoptotic bodies. In conclusion, our data demonstrate an ITC-induced mechanism leading to growth inhibition in A. thaliana and rat bladder cancer cells, and expose clues to the mechanisms underlying the physiological role of glucosinolates in vivo.
硫代葡萄糖苷生物降解产生的异硫氰酸盐（ITCs）是一类亲电试剂，与植物和哺乳动物细胞的生长抑制作用有关。这一特性的潜在作用方式尚未完全明确。由于ITCs具有化学预防潜力，因此对其作用方式的阐明涉及哺乳动物癌细胞。据报道，ITCs与微管蛋白的结合是其诱导细胞周期停滞和凋亡的一种机制。在本研究中，我们证明ITCs会破坏拟南芥中的微管，导致观察到的生长受抑制表型。我们还在大鼠膀胱癌细胞（AY - 27）中证实了这一点，表明植物和动物细胞具有共同的机制来响应ITCs对生长的影响。将拟南芥暴露于烯丙基异硫氰酸盐（AITC）的气相中会抑制生长，并以剂量依赖的方式导致叶片同时变白。转录分析表明，AITC处理后热休克基因会上调。利用表达绿色荧光蛋白标记的α - 微管蛋白的转基因拟南芥，显示AITC会导致微管在时间和剂量上依赖性地解体。用ITCs处理AY - 27细胞会导致细胞增殖在时间和剂量上依赖性地减少，并使细胞停滞在G2/M期。用ITCs处理瞬时转染以表达绿色荧光蛋白标记的α - 微管蛋白的AY - 27细胞，会导致微管丝消失并随后形成凋亡小体。总之，我们的数据证明了一种ITC诱导的机制，该机制导致拟南芥和大鼠膀胱癌细胞生长受到抑制，并揭示了硫代葡萄糖苷在体内生理作用的潜在机制线索。
