Structural requirements for the flavonoid-mediated modulation of glutathione S-transferase P1-1 and GS-X pump activity in MCF7 breast cancer cells
Structural requirements for the flavonoid-mediated modulation of glutathione S-transferase P1-1 and GS-X pump activity in MCF7 breast cancer cells
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DOI：
10.1016/j.bcp.2003.12.032
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发表时间：
2004-04-15
影响因子：
5.8
通讯作者：
Cnubben, NHP
中科院分区：
文献类型：
--
作者：
van Zanden, JJ;Geraets, L;Cnubben, NHP
本研究的目的是研究谷胱甘肽S-转移酶P1 - 1（GSTP1 - 1）和GS-X泵（MRP 1和MRP 2）活性抑制所需的结构要求，结构相关的黄酮类化合物，在GSTP1 - 1转染的MCF 7细胞（pMTG5）。结果表明，某些黄酮类化合物可抑制MCF 7 pMTG5细胞中GST P1 - 1的活性。特别是高良姜素在细胞暴露于25 μ M浓度时能够抑制几乎所有的细胞GST P1 - 1活性。其他类黄酮如山奈酚、圣草酚和槲皮素显示出中等的GST 1 - 1抑制潜力。对于GSTP1 - 1抑制，无法确定强效抑制所需的特定结构要求。大多数黄酮类化合物似乎是有效的GS-X转运抑制剂，IC 50值在0.8和8 μ M之间。木犀草素和槲皮素是最强的抑制剂，IC 50值分别为0.8和1.3 μ M。不含C_2-C_3双键的黄酮类化合物如圣草酚、花旗松素和儿茶素不抑制GS-X泵活性.本研究结果表明，黄酮类化合物高效抑制GS-X泵所必需的结构特征是：（1）羟基的存在，尤其是其中两个羟基产生3 ′，4-儿茶酚部分;和（2）由于存在C2-C3双键而形成平面分子。其他因素，如亲脂性和羟基总数似乎并不主导类黄酮介导的GS-X泵抑制。为了确定GS-X泵在MCF 7细胞中负责DNP-SG外排，使用转染的MDCKII细胞研究了三种特征性黄酮类化合物槲皮素、黄酮和紫杉叶素对MRP 1和MRP 2活性的影响。所有三种黄酮类化合物以及典型的MRP抑制剂（MK 571）以与在MCF7细胞中观察到的类似方式影响MRP 1介导的转运活性。此外，MCF 7细胞中最有效的GS-X泵抑制剂槲皮素不影响MRP 2介导的转运活性。这些结果表明，MCF 7细胞中的GS-X泵活性很可能是类黄酮介导的对MRP 1的抑制作用的结果，而不是对MRP 2的抑制作用。总之，本研究揭示了类黄酮与GSH依赖性毒物代谢酶相互作用的主要位点是GS-X泵MRP 1，而不是结合GST 1 - 1活性本身。在类黄酮中，特别是槲皮素是最活跃的，经常在功能性食品补充剂中销售。考虑到补充剂摄入后预期达到的生理水平，本研究的IC 50值指向可能的类黄酮-药物和/或类黄酮-异生物质相互作用，特别是关于涉及毒物代谢的转运过程。(C)2004爱思唯尔公司All rights reserved.
The objective of this study was to investigate the structural requirements necessary for inhibition of glutathione S-transferase P1-1 (GSTP1-1) and GS-X pump (MRP1 and MRP2) activity by structurally related flavonoids, in GSTP1-1 transfected MCF7 cells (pMTG5). The results reveal that GSTP1-1 activity in MCF7 pMTG5 cells can be inhibited by some flavonoids. Especially galangin was able to inhibit almost all cellular GSTP1-1 activity upon exposure of the cells to a concentration of 25 muM. Other flavonoids like kaempferol, eriodictyol and quercetin showed a moderate GSTP1-1 inhibitory potential. For GSTP1-1 inhibition, no specific structural requirements necessary for potent inhibition could be defined. Most flavonoids appeared to be potent GS-X transport inhibitors with IC50 values ranging between 0.8 and 8 muM. Luteolin and quercetin were the strongest inhibitors with IC50 values of 0.8 and 1.3 muM, respectively. Flavonoids without a C2-C3 double bond like eriodictyol, taxifolin and catechin did not inhibit GS-X pump activity.The results of this study demonstrate that the structural features necessary for high potency GS-X pump inhibition by flavonoids are (1) the presence of hydroxyl groups, especially two of them generating the 3',4-catechol moiety; and (2) a planar molecule due to the presence of a C2-C3 double bond. Other factors, like lipophilicity and the total number of hydroxyl groups do not seem to be dominating the flavonoid-mediated GS-X pump inhibition. To identify the GS-X pump responsible for the DNP-SG efflux in MCF7 cells, the effects of three characteristic flavonoids quercetin, flavone and taxifolin on MRP1 and MRP2 activity were studied using transfected MDCKII cells. All three flavonoids as well as the typical MRP inhibitor (MK571) affected MRP1-mediated transport activity in a similar way as observed in the MCF7 cells. In addition, the most potent GS-X pump inhibitor in the MCF7 cells, quercetin, did not affect MRP2-mediated transport activity. These observations clearly indicate that the GS-X pump activity in the MCF7 cells is likely to be the result of flavonoid-mediated inhibition of MRP1 and not MRP2.Altogether, the present study reveals that a major site for flavonoid interaction with GSH-dependent toxicokinetics is the GS-X pump MRP1 rather than the conjugating GSTP1-1 activity itself. Of the flavonoids shown to be most active especially quercetin is frequently marketed in functional food supplements. Given the physiological levels expected to be reached upon supplement intake, the IC50 values of the present study point at possible flavonoid-drug and/or flavonoid-xenobiotic interactions especially regarding transport processes involved in toxicokinetics. (C) 2004 Elsevier Inc. All rights reserved.