The existence of hormone-independent tumors is a substantial problem for the present endocrine treatment of breast cancers. Estrogen receptor (ER) gene mutation can change the biochemical activity of the protein and can affect hormone responsiveness. However, quite a few mutations of significance have been described in breast cancer. Recently, numerous variant ERs have been detected at the mRNA level with alternative splicing, yielding deletion of exon 3, 5, or 7. The truncated ER protein induced from variant mRNA could mainly be exhibited as a repressor through dominant negative effects on normal ER protein. The mechanism of the loss of hormone dependency is, however, still very complex. Further work to assess the correlation between clinical behavior and ER variants is required to determine whether these variants play a role in hormone-resistant disease. Additionally, the DNA methylation of the ER gene itself may control ER expression. These epigenetic changes can play an important role in the loss of hormone dependence in breast cancer.

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.