Traoré A, Baudrimont I, Ambaliou S, Dano S D, Creppy E E
Laboratory of Toxicology and Applied Hygiene, Faculty of Pharmaceutical Sciences, University Victor Segalen Bordeaux 2, 146, rue Léo-Saignat, 33076 Bordeaux, France.
Arch Toxicol. 2001 Apr;75(2):110-7. doi: 10.1007/s002040000188.
Okadaic acid (OA) is a shellfish toxin produced by dinoflagellates, in mussels. It is a potent tumour promoter and represents a potential threat to human health even at low concentrations. OA targets mainly the gastrointestinal tract in acute poisoning, causing diarrhoea. Therefore the present investigations were designed to study the ability of okadaic acid to induce cytotoxicity and DNA lesions in a human colonic cell line (Caco-2). Incubation of Caco-2 cells with OA (3.75-60 ng/ml, i.e. 4.6 x 10(-3)-7.5 x 10(-2) microM) causes a significant reduction in cell viability. Moreover, okadaic acid inhibits protein and DNA synthesis with, respectively, IC50 of 16 and 6.5 ng/ml after 24 h incubation. It also provokes cell cycle arrest, characterised by an increase in the number of S phase cells, correlated with a significant decrease in G0/G1 phase cells at high concentration. One of the main results obtained in these investigations is the apoptosis induced by OA in Caco-2 cells of intestinal origin, shown by DNA laddering in agarose gel electrophoresis (250-1000 base pairs). OA also induces clastogenic effects evaluated by DNA fragmentation analysis using the method of Higuchi and Aggarwal (52% for 60 ng/ml) and comet assay (increase of the frequency of comets and their tails length). Therefore, the cell death induced by OA seems clearly to be concentration-dependent after 24 h of incubation. The cytotoxic properties of okadaic acid and its ability to damage DNA result in cell death, mainly by apoptosis. Since consumption of shellfish contaminated with acceptable okadaic acid concentrations exposes colonic cells to harmful concentrations of this toxin, the possibility that OA would display its toxic effects on intestinal cells in vivo should be evaluated in human primary intestinal cells and human intestinal slices for cytotoxic effects, DNA fragmentation and apoptosis.
冈田酸（OA）是一种由甲藻产生的贝类毒素，存在于贻贝中。它是一种强效的肿瘤促进剂，即使在低浓度下也对人类健康构成潜在威胁。急性中毒时，OA主要作用于胃肠道，引起腹泻。因此，本研究旨在研究冈田酸在人结肠细胞系（Caco-2）中诱导细胞毒性和DNA损伤的能力。用OA（3.75 - 60 ng/ml，即4.6×10⁻³ - 7.5×10⁻² μM）孵育Caco-2细胞会导致细胞活力显著降低。此外，孵育24小时后，冈田酸分别以16和6.5 ng/ml的IC50抑制蛋白质和DNA合成。它还会引发细胞周期停滞，其特征是S期细胞数量增加，在高浓度下与G0/G1期细胞数量显著减少相关。这些研究中获得的主要结果之一是OA在肠道来源的Caco-2细胞中诱导凋亡，这通过琼脂糖凝胶电泳（250 - 1000碱基对）中的DNA梯带显示。OA还通过使用Higuchi和Aggarwal方法的DNA片段分析（60 ng/ml时为52%）和彗星试验（彗星频率及其尾部长度增加）评估诱导染色体断裂效应。因此，孵育24小时后，OA诱导的细胞死亡似乎明显呈浓度依赖性。冈田酸的细胞毒性特性及其损伤DNA的能力导致细胞死亡，主要通过凋亡。由于食用受可接受浓度冈田酸污染的贝类会使结肠细胞暴露于该毒素的有害浓度下，因此应在人原代肠道细胞和人肠道切片中评估OA在体内对肠道细胞产生毒性作用的可能性，包括细胞毒性、DNA片段化和凋亡。
