School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
School of Health and Social Services, Center for University-wide Education, Saitama Prefectural University, 820 San-Nomiya, Koshigaya, Saitama 343-8540, Japan; Nihon Pharmaceutical University, 10281 Komuro, Ina-machi, Kitaadachi-gun, Saitama 362-0806, Japan.
Toxicol In Vitro. 2024 Dec;101:105943. doi: 10.1016/j.tiv.2024.105943. Epub 2024 Sep 26.
Di-(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer in polyvinyl chloride products. DEHP exposure in humans is of great concern due to its endocrine-disrupting properties. In this study, we characterized the agonistic activities of DEHP and its five metabolites, mono-(2-ethylhexyl) phthalate (MEHP), 5OH-MEHP, 5oxo-MEHP, 5cx-MEPP and 2cx-MMHP against human nuclear receptors, peroxisome proliferator-activated receptor α (PPARα), pregnane X receptor (PXR), and constitutive androstane receptor (CAR) using transactivation assays. In the PPARα assay, the order of the agonistic activity was MEHP >> 5cx-MEPP >5OH-MEHP, 5oxo-MEHP >2cx-MMHP > DEHP, with DEHP significantly inhibiting MEHP-induced PPARα agonistic activity. This finding was compared to the results from in silico docking simulation. In the PXR assay, DEHP showed PXR agonistic activity more potent than that of MEHP, whereas the other metabolites showed little activity. In the CAR assay, none of the tested compounds showed agonistic activity. Moreover, the expression levels of PPARα-, PXR-, and CAR-target genes in HepaRG cells exposed to DEHP or MEHP were investigated using qRT-PCR analysis. As a result, exposure to these compounds significantly upregulated PXR/CAR target genes (CYP3A4 and CYP2B6), but not PPARα target genes (CYP4A11, etc.) in HepaRG cells. Taken together, these results suggest that direct PXR and/or indirect CAR activation by several DEHP metabolites may be involved in the endocrine disruption by altering hormone metabolism.
邻苯二甲酸二（2-乙基己基）酯（DEHP）广泛用作聚氯乙烯产品中的增塑剂。由于其具有内分泌干扰特性，人类接触 DEHP 引起了极大关注。在这项研究中，我们使用转激活测定法，对 DEHP 及其五种代谢物，单（2-乙基己基）邻苯二甲酸酯（MEHP）、5OH-MEHP、5oxo-MEHP、5cx-MEPP 和 2cx-MMHP 对人核受体、过氧化物酶体增殖物激活受体α（PPARα）、妊娠相关 X 受体（PXR）和组成型雄烷受体（CAR）的激动活性进行了表征。在 PPARα 测定中，激动活性的顺序为 MEHP＞5cx-MEPP＞5OH-MEHP、5oxo-MEHP＞2cx-MMHP＞DEHP，且 DEHP 可显著抑制 MEHP 诱导的 PPARα 激动活性。这一发现与计算机对接模拟的结果进行了比较。在 PXR 测定中，DEHP 表现出比 MEHP 更强的 PXR 激动活性，而其他代谢物则几乎没有活性。在 CAR 测定中，没有一种测试化合物表现出激动活性。此外，使用 qRT-PCR 分析研究了 HepaRG 细胞中 DEHP 或 MEHP 暴露后 PPARα、PXR 和 CAR 靶基因的表达水平。结果表明，这些化合物暴露后显著上调了 PXR/CAR 靶基因（CYP3A4 和 CYP2B6），而不是 HepaRG 细胞中的 PPARα 靶基因（CYP4A11 等）。综上所述，这些结果表明，几种 DEHP 代谢物通过改变激素代谢直接激活 PXR 和/或间接激活 CAR，可能参与了内分泌干扰。
