ABSTRACT
In previous investigations it was shown that the synthetic estrogen diethylstilbestrol (DES) induces a rise of the intracellular calcium level ([Ca2+]i) in C6 rat glioma cells [P. Tas, H. Stopper, K. Koschel, D. Schiffmann, Influence of the carcinogenic oestrogen diethylstilboestrol on the intracellular calcium level in C6 rat glioma cells. Toxic. In vitro 5 (1991) 463-465] which is accompanied by changes of the arrangement of the cytoskeleton. In the present study, we compared the induction of these effects in COS (monkey kidney cells) lacking estrogen receptors (ER) with those in RUCA-I (rat endometrial carcinoma) cells containing ER. The [Ca2+]i in RUCA-I and COS cells following 17beta-estradiol (ES), genistein (GEN), daidzein (DZ) and coumestrol (CES) treatment was analyzed. A significant increase of [Ca2+]i induced by all compounds was observed in RUCA-I cells. No effects were detected in COS cells after ES and GEN treatment. The anti-estrogen ICI 182780 completely blocked the ES-and GEN-induced rise of [Ca2+]i. Dose and time dependencies of changes of calcium levels were analyzed and a biphasic response could be observed. The actin staining showed disintegrated stress fibers in RUCA-I cells. The degree of the observed effects correlates with the known estrogenicity of the applied compounds (DES > ES > GEN). It remains to be elucidated whether or not the effects observed are mediated by the "classic" genomic estrogen receptor pathway or by alternate nongenomic or receptor-independent pathways.
Subject(s)
Calcium/metabolism , Estradiol/analogs & derivatives , Estradiol/pharmacology , Estrogen Antagonists/pharmacology , Estrogens, Non-Steroidal/pharmacology , Actins/metabolism , Animals , COS Cells , Chlorocebus aethiops , Coumestrol/pharmacology , Female , Fulvestrant , Genistein/pharmacology , Intracellular Fluid/drug effects , Intracellular Fluid/metabolism , Isoflavones/pharmacology , Phytoestrogens , Plant Preparations , Rats , Receptors, Estrogen/drug effects , Receptors, Estrogen/metabolism , Tumor Cells, CulturedABSTRACT
Prostaglandin-H-synthase (PHS) peroxidase has been suggested to mediate drug metabolism particularly in extrahepatic tissues low in monooxygenase (MFO) activity. PHS can oxidize various xenobiotics in vitro; its contribution in vivo is still uncertain and is currently assessed by differences in the MFO- and PHS-catalyzed product/adduct formation of a few suitable substrates. Cells in culture that are PHS competent but MFO deficient can provide an additional approach for further investigating the role of PHS in the metabolic activation of foreign compounds. To this end, a cell line has been derived from ram seminal vesicles (SEMV), a tissue known as a good source of PHS but shown to be devoid of MFO activity. SEMV cells can be cultured in IBR or in RPMI medium supplemented with fetal calf serum, and have been subcultured until passage 30. The arachidonic acid (AA) metabolism in these cells has been characterized: besides incorporation in the lipid pool, AA was mainly metabolized to prostaglandin (PG) E2; minor products were PGF2 alpha and the lipoxygenase products 12- and 15-HETE. The PGE2 production (17 nmol/10(6) cells.24 h) of SEMV cells (passage 10) exceeded at least 10-fold that of other cells cultured under similar conditions. These data, indicative of high PHS activity, suggest that the cells can be a useful tool for future studies on the objectives outlined above.