Assessment Of Endocrine-disrupting Effects Of Typical Pesticides And Metals Through Interference With Glucocorticoid Receptor And Mineralocorticoid Receptor Via In Vitro Bioassay

Pesticides and metals are important pollutants in the modern era.An annual amount of 1 to 2.5 million tons of pesticides is applied to agricultural,residential,and public health protection sites globally.These man-made chemicals are deliberately released into the environment,and their parent compounds or metabolites are often found in the environment and biota.As a result of human activities,such as mining and E-waste,the pollution of metals was ubiquitous in environment and attracted public attention.An increasingly number of studies has shown that pesticides and metals may act as endocrine-disrupting chemicals(EDCs)by interfering with hormone receptors as agonists or antagonists.Glucocorticoid receptor(GR)and mineralocorticoid receptor(MR)have essential physiological functions on a variety of target tissues such as kidney,colon,adipose tissue,cardiovascular and central nervous systems.The disruption of GR and MR may contribute to serious adverse outcomes including nervous disease,immune disorder,metabolic syndrome and colorectal carcinoma.However,data regarding the possible environmental ligands for GR and MR are still extremely sparse in EDCs research.Comprehensive screening and evaluation of GR and MR antagonists and agonists should be considered to better understand the health and ecological risks.(1)In this chapter,the glucocorticoidic and anti-glucocorticoidic effects of 34 pesticides on human GR were investigated using luciferase reporter gene assay.Surprisingly,none of the test chemicals showed GR agonistic activity,but 12 chemicals exhibited apparent antagonistic effects.Bifenthrin,X-cyhalothrin,cypermethrin,resmethrin,o,p'-DDT,p,p'-DDT,methoxychlor,ethiofencarb and tolylfluanid showed remarkable GR antagonistic properties with RIC20 lower than 10-6 M.The disruption of glucocorticoid-responsive genes in H4IIE and J774A.1 cells was further evaluated on these 12 GR antagonists.In H4IIE cells,four organochlorine insecticides,bifenthrin and 3-PBA decreased cortisol-induced PEPCK gene expression,while o,p'-DDT and methoxychlor inhibited cortisol-stimulated Arg and TAT genes expression.Cypermethrin and tolyfluanid attenuated cortisol-induced TAT expression.And in J774A.1 cells,?-cyhalothrin,resmethrin,3-PBA,o,p'-DDT,p,p'-DDT,p,p'-DDE,methoxychlor and tolylfluanid reduced cortisol-stimulated GILZ expression.Furthermore,molecular docking simulation indicated that different interactions may stabilize the binding between molecules and GR.(2)In this chapter,a total of 43 pesticides and/or metabolites were investigated for their potential effects on human MR.None of the tested pesticides exhibited MR agonistic potency,whereas 16 compounds showed antagonistic activities.Further investigations indicated that these 16 chemicals individually antagonized aldosterone-induced alkaline phosphatase expression in vascular smooth muscle cells and aldosterone-inhibited hepatocellular carcinoma cell proliferation at higher concentrations,and the mixture of these 16 pesticides at environmentally relevant concentrations significantly disrupted MR activity.The additional quantitative mixture experiments indicated a good agreement between the combined anti-mineralocorticoidic activities of 16 pesticides and the responses predicted by concentration addition model instead of independent action model.The interruption of nuclear translocation of MR was clarified as a main mechanism for the anti-mineralocorticoidic activities by these pesticides.These data suggest that the health risk may increase when multiple MR antagonists cooperate following concentration addition model and exhibit a combined effect.(3)In this chapter,we sought to recognize potential GR and MR agonists or antagonists among 15 metals that includes nonessential metals,such as Pb and Cd,and some essential micronutrients,such as Cu and Zn,using dual-luciferase reporter assays,and subsequently evaluate their effects on glucocorticoid-responsive gene expression and aldosterone-induced hepatocellular carcinoma growth suppression.None of the tested metals exhibited GR or MR agonistic activity,but there were 7 and 5 candidate metals showed obvious GR and MR antagonistic properties,respectively.As far as we know,Ba(?),Co(?),Pb(?),Sn(?),and Zn(?)were first reported to interrupt the GR-mediated transcriptional activities.This is also the first study to identify Cd(?),Pb(?),Li(?),Mn(?),and Sn(?)as MR antagonists.Among these metals,Pb(?),Li(?),and Sn(?)showed both anti-glucocorticoid and anti-mineralocorticoid activities.Ba(?),Co(?),Cu(?)and Zn(?)only inhibited GR transactivation,while Cd(?)and Mn(?)only antagonized the MR activity.