Intestinal epithelial cell accumulation of the cancer preventive polyphenol ellagic acid - extensive binding to protein and DNA
Intestinal epithelial cell accumulation of the cancer preventive polyphenol ellagic acid - extensive binding to protein and DNA
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DOI：
10.1016/s0006-2952(03)00413-1
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发表时间：
2003-09-15
影响因子：
5.8
通讯作者：
Walle, T
中科院分区：
文献类型：
--
作者：
Whitley, AC;Stoner, GD;Walle, T
鞣花酸（EA）是一种存在于许多浆果中的多酚，已被证明在动物食管癌的起始和促进阶段都具有预防作用。为了能够将这些发现外推到人类，我们研究了[C-14]EA在人肠Caco-2细胞中的跨细胞吸收和上皮细胞积累。10 μ M [C-14]EA的顶端（粘膜）到基底外侧（浆膜）的跨细胞转运是最小的，P-app仅为0.13 x 10（-6）cm/s，这小于细胞旁转运标记甘露醇。尽管观察到基底外侧至顶端流出，但Caco-2细胞摄取研究显示EA在细胞中的高蓄积（1054 +/- 136 pmol/mg蛋白），表明穿过顶端膜的吸收转运较容易。令人惊讶的是，多达93%的细胞EA与大分子不可逆地结合（982 +/-151 pmol/mg蛋白质）。为了证实与蛋白质结合的不可逆性质，对用10 μ M [C-14]EA处理的Caco-2细胞进行SDS-PAGE分析。这导致放射性标记的蛋白条带被捕获在堆积凝胶中，与[14 C] EA交联蛋白一致。用10 μ M [14 C]EA处理Caco-2细胞也显示EA与细胞DNA的不可逆结合比蛋白质高5倍（5020 +/- 773 pmol/mg DNA）。而不可逆的结合蛋白质需要氧化EA的活性氧物种，这似乎不是与DNA结合的情况。与细胞DNA和蛋白质的不可逆结合可能是其高度限制跨细胞吸收的原因。因此，EA似乎选择性地积聚在呼吸消化道的上皮细胞中，在那里可以显示其癌症预防作用。(C)2003年爱思唯尔公司All rights reserved.
Ellagic acid (EA), a polyphenol present in many berries, has been demonstrated to be preventive of esophageal cancer in animals both at the initiation and promotion stages. To be able to extrapolate these findings to humans we have studied the transcellular absorption and epithelial cell accumulation of [C-14]EA in the human intestinal Caco-2 cells. The apical (mucosal) to basolateral (serosal) transcellular transport of 10 muM [C-14]EA was minimal with a P-app of only 0.13 x 10(-6) cm/s, which is less than for the paracellular transport marker mannitol. In spite of observations of basolateral to apical efflux, Caco-2 cell uptake studies showed high accumulation of EA in the cells (1054 +/- 136 pmol/mg protein), indicating facile absorptive transport across the apical membrane. Surprisingly, as much as 93% of the cellular EA was irreversibly bound to macromolecules (982 +/- 151 pmol/mg protein). To confirm the irreversible nature of the binding to protein, Caco-2 cells treated with 10 muM [C-14]EA were subjected to SDS-PAGE analysis. This resulted in radiolabeled protein bands trapped in the stacking gel, consistent with [14C]EA-crosslinked proteins. Treatment of Caco-2 cells with 10 PM [14C]EA also revealed irreversible binding of EA to cellular DNA as much as five times higher than for protein (5020 +/- 773 pmol/mg DNA). Whereas the irreversible binding to protein required oxidation of EA by reactive oxygen species, this did not seem to be the case with the DNA binding. The avid irreversible binding to cellular DNA and protein may be the reason for its highly limited transcellular absorption. Thus, EA appears to accumulate selectively in the epithelial cells of the aerodigestive tract, where its cancer preventive actions may be displayed. (C) 2003 Elsevier Inc. All rights reserved.