Skip to main content
Advertisement

Main menu

  • Home
  • Articles
    • Current Issue
    • Fast Forward
    • Latest Articles
    • Special Sections
    • Archive
  • Information
    • Instructions to Authors
    • Submit a Manuscript
    • FAQs
    • For Subscribers
    • Terms & Conditions of Use
    • Permissions
  • Editorial Board
  • Alerts
    • Alerts
    • RSS Feeds
  • Virtual Issues
  • Feedback
  • Submit
  • Other Publications
    • Drug Metabolism and Disposition
    • Journal of Pharmacology and Experimental Therapeutics
    • Molecular Pharmacology
    • Pharmacological Reviews
    • Pharmacology Research & Perspectives
    • ASPET

User menu

  • My alerts
  • Log in
  • My Cart

Search

  • Advanced search
Molecular Pharmacology
  • Other Publications
    • Drug Metabolism and Disposition
    • Journal of Pharmacology and Experimental Therapeutics
    • Molecular Pharmacology
    • Pharmacological Reviews
    • Pharmacology Research & Perspectives
    • ASPET
  • My alerts
  • Log in
  • My Cart
Molecular Pharmacology

Advanced Search

  • Home
  • Articles
    • Current Issue
    • Fast Forward
    • Latest Articles
    • Special Sections
    • Archive
  • Information
    • Instructions to Authors
    • Submit a Manuscript
    • FAQs
    • For Subscribers
    • Terms & Conditions of Use
    • Permissions
  • Editorial Board
  • Alerts
    • Alerts
    • RSS Feeds
  • Virtual Issues
  • Feedback
  • Submit
  • Visit molpharm on Facebook
  • Follow molpharm on Twitter
  • Follow molpharm on LinkedIn
Abstract

Elevation of pi class glutathione S-transferase activity in human breast cancer cells by transfection of the GST pi gene and its effect on sensitivity to toxins.

J A Moscow, A J Townsend and K H Cowan
Molecular Pharmacology July 1989, 36 (1) 22-28;
J A Moscow
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
A J Townsend
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
K H Cowan
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • Info & Metrics
  • eLetters
  • PDF
Loading

Abstract

Increased expression of the glutathione S-transferase (GST; E.C.2.5.1.18) pi class isozyme is associated with both malignant transformation and drug resistance, as well as with decreased estrogen receptor content in breast cancer. In order to further characterize the role of this enzyme in drug resistance, we cloned the cDNA encoding the human isozyme GST pi and developed two eukaryotic expression vectors using this cDNA and either the human metallothionein IIa or cytomegalovirus immediate-early promoters. These GST pi expression vectors were cotransfected with pSV2neo into drug-sensitive MCF-7 human breast cancer cells, which have low amounts of GST activity and which do not express GST pi. The transfected cells were selected for G418 resistance and individual clones were screened for GST activity. Three clones that demonstrated increased GST activity were selected for further study. Immunoprecipitation studies demonstrated that the increase in GST activity in these clones was due to expression of GST pi. Although the total GST activity of the positive clones was increased as much as 15-fold over that in wild-type MCF-7 cells, there was no change in glutathione peroxidase activity, as measured using cumene hydroperoxide as a substrate. Immunoblot studies revealed that the increased GST enzyme produced in the transfected cells was identical in size to endogenous GST pi. Southern blot analysis demonstrated the incorporation of the GST pi expression vector into the genome of the positive clones and Northern blot analysis showed that the transfected genes made a hybrid GST pi RNA that was slightly larger than the endogenous GST pi RNA. Primer extension studies demonstrated that this increase in length corresponded to the added length of the 5' leader sequence of the expression vector. The effect of increased GST pi activity on the sensitivity of the transfected clones to several cytotoxic agents was assessed by colony-forming assay. The transfected clones were slightly more resistant (1.3-4.1-fold) to benzo(a)pyrene and its toxic metabolite benzo(a)pyrene-(anti)-7,8-dihydrodiol-9,10-epoxide, as well as to ethacrynic acid (3.1-to 4.4-fold). Although increased GST pi expression is found in MCF-7 cells selected for doxorubicin resistance, the transfected clones were not consistently more resistant to doxorubicin than control cells. In addition, the transfected cells were not resistant to either melphalan or (cis)-platinum, even though conjugation with glutathione is known to play a role in the detoxification of both of these drugs.(ABSTRACT TRUNCATED AT 400 WORDS)

MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years. 

Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page. 

 

  • Click here for information on institutional subscriptions.
  • Click here for information on individual ASPET membership.

 

Log in using your username and password

Forgot your user name or password?

Purchase access

You may purchase access to this article. This will require you to create an account if you don't already have one.
PreviousNext
Back to top

In this issue

Molecular Pharmacology
Vol. 36, Issue 1
1 Jul 1989
  • Table of Contents
  • Table of Contents (PDF)
  • Index by author
  • Back Matter (PDF)
  • Editorial Board (PDF)
  • Front Matter (PDF)
Download PDF
Article Alerts
Sign In to Email Alerts with your Email Address
Email Article

Thank you for sharing this Molecular Pharmacology article.

NOTE: We request your email address only to inform the recipient that it was you who recommended this article, and that it is not junk mail. We do not retain these email addresses.

Enter multiple addresses on separate lines or separate them with commas.
Elevation of pi class glutathione S-transferase activity in human breast cancer cells by transfection of the GST pi gene and its effect on sensitivity to toxins.
(Your Name) has forwarded a page to you from Molecular Pharmacology
(Your Name) thought you would be interested in this article in Molecular Pharmacology.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Citation Tools
Abstract

Elevation of pi class glutathione S-transferase activity in human breast cancer cells by transfection of the GST pi gene and its effect on sensitivity to toxins.

J A Moscow, A J Townsend and K H Cowan
Molecular Pharmacology July 1, 1989, 36 (1) 22-28;

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero

Share
Abstract

Elevation of pi class glutathione S-transferase activity in human breast cancer cells by transfection of the GST pi gene and its effect on sensitivity to toxins.

J A Moscow, A J Townsend and K H Cowan
Molecular Pharmacology July 1, 1989, 36 (1) 22-28;
del.icio.us logo Digg logo Reddit logo Twitter logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Jump to section

  • Article
  • Info & Metrics
  • eLetters
  • PDF

Related Articles

Cited By...

Similar Articles

Advertisement
  • Home
  • Alerts
Facebook   Twitter   LinkedIn   RSS

Navigate

  • Current Issue
  • Fast Forward by date
  • Fast Forward by section
  • Latest Articles
  • Archive
  • Search for Articles
  • Feedback
  • ASPET

More Information

  • About Molecular Pharmacology
  • Editorial Board
  • Instructions to Authors
  • Submit a Manuscript
  • Customized Alerts
  • RSS Feeds
  • Subscriptions
  • Permissions
  • Terms & Conditions of Use

ASPET's Other Journals

  • Drug Metabolism and Disposition
  • Journal of Pharmacology and Experimental Therapeutics
  • Pharmacological Reviews
  • Pharmacology Research & Perspectives
ISSN 1521-0111 (Online)

Copyright © 2023 by the American Society for Pharmacology and Experimental Therapeutics