Journal Article

Cellular protein kinase C isozyme regulation by exogenously delivered physiological disulfides—implications of oxidative protein kinase C regulation to cancer prevention

Feng Chu, Li Hua Chen and Catherine A. O'Brian

in Carcinogenesis

Volume 25, issue 4, pages 585-596
Published in print April 2004 | ISSN: 0143-3334
Published online April 2004 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgh041
Cellular protein kinase C isozyme regulation by exogenously delivered physiological disulfides—implications of oxidative protein kinase C regulation to cancer prevention

More Like This

Show all results sharing this subject:

  • Clinical Cytogenetics and Molecular Genetics

GO

Show Summary Details

Preview

We reported previously that cystine produces regulatory responses in purified, recombinant human protein kinase C-δ (PKCδ) and PKCε via S-thiolation-triggered mechanisms that are consistent with a cancer preventive effect, i.e. stimulation of the pro-apoptotic, tumor-suppressive isozyme PKCδ and inactivation of the growth-stimulatory, oncogenic isozyme PKCε, at S-cysteinylation stoichiometries that correspond to modification of a single redox-regulatory cysteine (Cys) switch in each isozyme. In this report, we show that the oxidative regulatory responses of purified PKCδ and PKCε to cystine are recapitulated in disulfide-treated cells. We report that treatment of COS7-PKCε transfectants with the cystine precursor cystine dimethyl ester (CDME) produced concentration- and time-dependent PKCε inactivation that was associated with oxidative PKCε modification manifested as attenuated band intensity in PKCε immunoblot analyses, and that both PKCε inactivation and modification were reversed by dithiothreitol (DTT) as well as by thioredoxin. We also show that CDME induced biphasic PKCδ regulation in COS7-PKCδ transfectants, with DTT-irreversible PKCδ stimulation at low and DTT-reversible PKCδ inactivation at high CDME concentrations. The degrees of PKCδ versus PKCε inactivation by CDME treatment of COS7-PKC transfectants indicate substantial resistance of PKCδ to inactivation. The PKCδ stimulatory response in COS7-PKCδ cells was triggered only by the disulfide agent and not by its reduced thiol counterpart, providing evidence for an oxidative mechanism. Also paralleling the oxidative stimulation of purified PKCδ by cystine, the stimulation of PKCδ elicited by CDME treatment of cells involved a stable structural change, which was evident from the stability of the stimulated form of PKCδ to immunoprecipitation. Demonstration of oxidative regulation of cellular PKCδ and PKCε by disulfides in this report provides evidence that redox-regulatory sites in PKCδ and PKCε may offer novel targets for development of cancer preventive or therapeutic agents that selectively inactivate PKCε or stimulate PKCδ.

Keywords: βME, β-mercaptoethanol; CDME, cystine dimethyl ester; Cys, cysteine; DAG, diacylglycerol; DMBA, dimethylbenz[a]anthracene; DTT, dithiothreitol; FBS, fetal bovine serum; GSH, glutathione; IP, immunoprecipitate; NAC, N-acetylcysteine; PE, phorbol ester; PKC, protein kinase C; PS, phosphatidylserine; TPA, 12-O-tetradecanoylphorbol-13-acetate; TP/P, tumor promotion/progression

Journal Article.  9057 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.