Activation of kinase pathways in MCF-7 cells by 17β-estradiol and structurally diverse estrogenic compounds

Abstract

17β-Estradiol (E2) activates non-genomic pathways in MCF-7 cells, and this study investigates the effects of structurally-diverse estrogenic compounds on activation of mitogen-activated protein kinase (MAPK), phosphatidylinositol-3-kinase (PI3-K), protein kinase C (PKC), PKA, and calcium calmodulin-dependent kinase IV (CaMKIV). Activation of kinases was determined by specific substrate phosphorylation and transactivation assays that were diagnostic for individual kinases. The compounds investigated in this study include E2, diethylstilbestrol (DES), the phytoestrogen resveratrol, and the following synthetic xenoestrogens, bisphenol-A (BPA), nonylphenol, octylphenol, endosulfan, kepone, 2,2-bis( p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), and 2′,3′,4′,5′-tetrachloro-4-biphenylol (HO-PCB-Cl 4). With the exception of resveratrol, all the compounds activated PI3-K and MAPK. Activation of PKC by the xenoestrogens was structure-dependent since resveratrol, kepone and HO-PCB-Cl 4 were inactive and only minimal activation of PKA was observed. CaMKIV was activated only by E2 and DES, and HO-PCB-Cl 4 was a potent inhibitor of CaMKIV-dependent activity. These results demonstrate that activation of estrogen receptor-α-mediated non-genomic pathways by estrogenic compounds in MCF-7 cells is structure-dependent and can result in activation or inhibition of kinase activities.