The mechanism of the antiproliferative effect of nonsteroidal antiestrogens (tamoxifen, hydroxytamoxifen) is discussed from studies performed in human breast cancer cell lines. At least two types of mechanism have been evidenced. In the presence of estrogens, antiestrogens behave as classical antihormones and their inhibition of cell proliferation is likely due to inhibition of the synthesis and release of several estrogen-induced mitogens (growth factors and proteases). In the absence of estrogens (cells cultured in phenol-red-free medium), antiestrogens can still inhibit the effect of growth factors (EGF, insulin). At concentrations ≤ 4 µM, antiestrogens are also cytotoxic and they require accessible estrogen receptors for their action. ‘Estrogen-receptor-targeted drugs’ is therefore a better general term than ‘antiestrogens’ to describe the mechanism of action of these drugs, which can also function without inhibiting estrogen action.

Keywords:
Antiestrogens, Estrogen receptor, Breast cancer, Growth factor, Cytotoxicity, Targeted drug
This content is only available via PDF.
© 1987 S. Karger AG, Basel
1987
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.