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Radiolabeled antiestrogens: Synthesis, metabolism and receptor interaction studies
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KS Dissociated efficacy of Tamoxifen to induce estrogen specific mRNA and proteins in MCF cells variants. H. Rochefort-, F. May, F. Vignon and B. Westley_, INSE%M U 148 (60, rue de Navacelles) - 34100 Montpellier, France. Antiestrogens are estrogen weak agonist for the iegulation of progesterone receptor sites. We have studied the regulation by Tamoxifen of other estrogen specific responses, namely the pS mRNA titrated by northern blot using cDNi5 probe and two secreted pro&ins of 52 and 160 kilodaltons labeled by S Methionine (Cell, 20, 353-362, 1980). In the wild type MCF7 we show that Tam is unable to increase the level of pS mRNA. In two antiestrogen resistant clones R27 (,M. Lippman et al.) an 2 RTx8 (F. Bayard et al.) Tam remained unable to stimulate the pS2 mRNA and the 160 K secreted protein but became active to stimulate the production of the 52 K protein. One conclude that lo antiestrogens are totally unable to stimulate the transcription of some estrogen regulated genes but that they partially activate the RE for increasing the production of RP sites. 2O That in some RE positive antiestrogen resistant cells, antiestrogen became full estrogens agonists for some (52 K protein) but not all (pS2 mRNA, 160 K protein) estrogen specific responses. The general implication concerning the function of the 52 K protein in the regulation of cell proliferation and the mechanism of action of Tamoxifen in antiestrogen responsive and resistant cells will be discussed. Supported by INSERM and Universiti! de Montpellier 1.
K6 ~DIOL~ELED ANTIESTROCENS: SYNTHESIS, MET~OLISM AND RECEPTOR INTERACTION John A. Katzenellenbc~en*. STUDIES. School of Chemical Sciences, University of Illinois, Urbana, IL 61801. We have prepared several antiestrogens in high specific activity Studies with these agents in viva have revealed tritium-labeled form. that more polar metabolites with higher affinity for the estrogen receptor We accumulate selectively in the nuclear fraction of target tissue cells. have identified some of these metabolites and prepared them in radiolabeled Arylform in order to study their interaction with the estrogen receptor. ethylene non-steroidal estrogens and antiestrogens bearing a phenolic hydroxyl group situated para to the double bond (such as diethylstilbestrol In each and hydroxytamoxifen) undergo facile cis-trans isomerization. case, the trans isomer is bound very strongly by the estrogen receptor, and Because the isomerization is so facile, it is diffithe cis only weakly. cult to conduct experiments to establish the biological activity of the cis isomers, because isomerization during the experiment results in receptor occupancy by the trans isomer. Tamoxifen aziridine, a covalent binding derivative of the antiestrogen tamoxifen, has been used to affinity label The physicothe estrogen receptor with high efficiency and selectivity. chemical properties of the covalently-labeled high resolution under denaturing conditions, receptor degradation can be followed easily. AM 15556.
receptor can be studied with and the nature and rate of Supported by NIH grant
KS Dissociated efficacy of Tamoxifen to induce estrogen specific mRNA and proteins in MCF cells variants. H. Rochefort-, F. May, F. Vignon and B. Westley_, INSE%M U 148 (60, rue de Navacelles) - 34100 Montpellier, France. Antiestrogens are estrogen weak agonist for the iegulation of progesterone receptor sites. We have studied the regulation by Tamoxifen of other estrogen specific responses, namely the pS mRNA titrated by northern blot using cDNi5 probe and two secreted pro&ins of 52 and 160 kilodaltons labeled by S Methionine (Cell, 20, 353-362, 1980). In the wild type MCF7 we show that Tam is unable to increase the level of pS mRNA. In two antiestrogen resistant clones R27 (,M. Lippman et al.) an 2 RTx8 (F. Bayard et al.) Tam remained unable to stimulate the pS2 mRNA and the 160 K secreted protein but became active to stimulate the production of the 52 K protein. One conclude that lo antiestrogens are totally unable to stimulate the transcription of some estrogen regulated genes but that they partially activate the RE for increasing the production of RP sites. 2O That in some RE positive antiestrogen resistant cells, antiestrogen became full estrogens agonists for some (52 K protein) but not all (pS2 mRNA, 160 K protein) estrogen specific responses. The general implication concerning the function of the 52 K protein in the regulation of cell proliferation and the mechanism of action of Tamoxifen in antiestrogen responsive and resistant cells will be discussed. Supported by INSERM and Universiti! de Montpellier 1.
K6 ~DIOL~ELED ANTIESTROCENS: SYNTHESIS, MET~OLISM AND RECEPTOR INTERACTION John A. Katzenellenbc~en*. STUDIES. School of Chemical Sciences, University of Illinois, Urbana, IL 61801. We have prepared several antiestrogens in high specific activity Studies with these agents in viva have revealed tritium-labeled form. that more polar metabolites with higher affinity for the estrogen receptor We accumulate selectively in the nuclear fraction of target tissue cells. have identified some of these metabolites and prepared them in radiolabeled Arylform in order to study their interaction with the estrogen receptor. ethylene non-steroidal estrogens and antiestrogens bearing a phenolic hydroxyl group situated para to the double bond (such as diethylstilbestrol In each and hydroxytamoxifen) undergo facile cis-trans isomerization. case, the trans isomer is bound very strongly by the estrogen receptor, and Because the isomerization is so facile, it is diffithe cis only weakly. cult to conduct experiments to establish the biological activity of the cis isomers, because isomerization during the experiment results in receptor occupancy by the trans isomer. Tamoxifen aziridine, a covalent binding derivative of the antiestrogen tamoxifen, has been used to affinity label The physicothe estrogen receptor with high efficiency and selectivity. chemical properties of the covalently-labeled high resolution under denaturing conditions, receptor degradation can be followed easily. AM 15556.
receptor can be studied with and the nature and rate of Supported by NIH grant