人参皂苷Rg1对TCDD致HepG2细胞CYP1A1诱导的抑制作用

The inhibitory effect of Rg1 on TCDD induced CYP1A1 in HepG2 cells

目的人参对多种肿瘤具有非器官特异性的预防作用,该文对人参皂苷Rg1与2,3,7,8-四氯代二苯并-对-二噁英(2,3,7,8-tetrachlorodibenzo-p-dioxin,TCDD)共同作用HepG2细胞,对CYP1A1在mRNA、蛋白及酶活性3个层面影响进行了研究,同时对CYP1A1转录调控子芳烃受体(AhR)表达情况亦进行了检测,旨在探索人参皂苷与TCDD共同作用时对CYP1A1影响,为干预前致癌物如TCDD等通过CYP1A1代谢活化产生致癌作用提供线索。方法该实验分别以TCDD 5 nmol·L-1单独作用或与Rg1(1.0、10.0、100.0μmol·L-1)共同作用于HepG2细胞24 h。溶剂对照组为二甲基亚砜(dimethyl suffoxide,DMSO)。利用RT-PCR法和Western blot法检测不同药物处理后HepG2细胞中CYP1A1、AhR的mRNA和蛋白质表达水平的变化,同时采用EROD法测定不同处理组细胞CYP1A1酶活性。结果与溶剂对照组比较,TCDD能使CYP1A1基因、蛋白表达上调及酶活性水平上升;与TCDD单独处理细胞组比较,Rg1与TCDD共处理组CYP1A1、AhR在mRNA和蛋白质表达水平均较TCDD单独处理组明显降低(P<0.01);同时CYP1A1酶活性也较单独TCDD处理组明显降低(P<0.01)。结论人参皂苷Rg1对TCDD致HepG2细胞CYP1A1诱导在mRNA、蛋白表达及酶活性3个层面均具有抑制作用,为深入研究人参皂苷Rg1对TCDD致肝脏损伤的保护作用提供线索。

Aim To investigate the impacts of the combination of ginsenoside Rgl and the AhR ligand of TCDD on CYP1A1 mRNA, protein, and enzyme activi- ty. Methods HepG2 cells were treated with either 5 nmol ·L^-1 TCDD alone or ginsenoside Rgl （ 1.0, 10. 0, 100.0 μmol·L^-1） plus 5 nmol·L^-1 TCDD or dimethylsulfoxide （DMSO, solvent control, 〈 1%） for 24 h. The activities of CYP1A-associated deethylation of ethoxyresorufin （EROD） were measured. Expres- sions of CYP1A1 at mRNA and protein levels were de- tected by RT-PCR and Western blot, respectively. Meanwhile, the expression of AhR, transcriptional reg- ulator of CYP1A1 was measured. Results Compared with control group, the mRNA, protein and enzyme ac- tivity expressions of CYP1 A1 significantly increased in TCDD group （P 〈0.01）, However, the CYP1A1 ac- ti＇vities were effectively decreased in co-exposed ginsen- oside Rgl and TCDD groups compared with the TCDD alone treated group （P 〈 0. 01 ）. Meanwhile, the mR- NA and protein expressions of CYP1 A1 and AhR were down-regulated. Conclusions Co-exposure of ginsen- oside Rgl and TCDD decreases the induced EROD ac- tivities, as well as the CYP1 A1 and AhR transcription- al level and protein level when compared with the TC- DD treated group. It is suggested ginsenoside maybe reduce the toxicity of TCDD on AhR-CYP1 A1 pathways as an AhR hgand.