The proposed research will investigate mechanisms by which the chlorinated hydrocarbons 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated biphenyls (PCBs) have disruptive effects on placental- uterine function. The hypothesis is that TCDD and PCBs alter placental- uterine paracrine and autocrine networks which are important for trophoblast invasiveness, proliferation and hormone secretion, as well as uterine cell growth. The major networks involve epidermal growth factor (EGF) and its receptor (EGF-R), transforming growth factors (TGFs)-alpha and -betas, the cytokine interleukin (IL) -1B and the protease inhibitor, plasminogen activator inhibitor (PAI). The PCB congeners 3,3',4,4'-tetrachloro and 2,2',4,4',5,5'-hexachloro, and the mixture Arochlor 1254 will be studied to represent different levels of AHH induction activity.
SPECIFIC AIM #1 : Does exposure of cultured human placental trophoblstic cell lines to TCDD and PCBs alter expression of genes important for placental growth and endocrine function? Experiments will specifically evaluate: a) EGF receptor binding and kinase activity in choriocarcinoma JEG-3 and BeWo cell lines to determine whether there is down-regulation of receptors with altered cell proliferation or hormone secretion; b) The genes recognized to be regulated by TCDD in other human cell lines, including TGF-alpha, TGF-betas, IL-1B, and PAI; c) Induction of cytochrome P-450 1A1 and PCB metabolism to determine if there are dose- related effects in parallel with changes in EGF receptors and/or growth factor expression through the Ah receptor.
SPECIFIC AIM #2 : Does exposure of cultured human endometrial adenocarcinoma cells to PCBs and TCDD alter expression of growth regulatory genes? Experiments will evaluate: a) EGF-R binding and kinase activity and EGF-stimulated cell proliferation; b) Estrogen receptor levels to determine whether the cellular response to estrogens is altered; c) Expression of TGF-alpha, TGF-betas, IL-1B, and PAI; d) Induction of cytochrome P450 1A1 and PCB metabolism for dose-response relationships with a), b) and c) above.
SPECIFIC AIM #3 : In pregnant rats, does administration of TCDD and the respective PCBs alter expression of placental genes for P450 1A1,TGFs- alpha and -beta, IL-1B and PAI in correlation with feto-placental growth retardation? Experiments will evaluate: a) Feto-placental growth in late gestation; b) Expression of TGF-alpah, TGF-betas, IL-1B, and PAI in placenta and decidua; c) Cytochrome P450 1A1 induction and PCB metabolism for dose response relationships with a) and b) above.
SPECIFIC AIM #4 : Is expression of placental amino acid transport systems altered in correlation with feto-placental growth retardation in pregnant rats treated with PCBs and TCDD? a) Amino acid transport via Systems B,+,y+,XAG-, and A will be examined in isolated vesicle preparations from the microvillous and basal membranes; b) mRNA levels will be examined utilizing cDNA probes to Systems y+ and XAG-; c) Cytochrome P450 1A1 induction for dos-response relationships with a) and b) above.
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