Upregulation of PKCη by PKCε and PDK1 involves two distinct mechanisms and promotes breast cancer cell survival

Deepanwita Pal, Shalini Persaud Outram, Alakananda Basu

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12 Citations (Scopus)

Abstract

Background Protein kinase C (PKC) serves as the receptor for tumor-promoting phorbol esters, which are potent activators of conventional (c) and novel (n) PKCs. We recently showed that these activators induced selective upregulation of PKCη in breast cancer cells. The objective of this study is to understand unique regulation of PKCη and its importance in breast cancer. Methods The levels of PKC isozymes were monitored in breast cancer cells following treatment with inhibitors of kinases, proteasome and proteases by Western blotting. PKCε was introduced by adenoviral delivery. PKCη and PDK1 were depleted by siRNA silencing. Cell growth was determined by the MTT or clonal assay. Results The general PKC inhibitors Gö 6983 and bisindolylmaleimide but not cPKC inhibitor Gö 6976 led to substantial PKCη downregulation, which was partly rescued by the introduction of nPKCε. Inhibition of phosphoinositide-dependent kinase-1 (PDK1) by Ly294002 or knockdown of PDK1 also led to downregulation of basal PKCη but had no effect on PKC activator-induced upregulation of PKCη. Proteasome inhibitors blocked PKCη downregulation triggered by PDK1 inhibition/depletion but not by Gö 6983. PKCη level increased in malignant but not in non-tumorigenic or pre-malignant cells in the progressive MCF-10A series associated with activated PDK1, and knockdown of PKCη inhibited breast cancer cell growth and clonogenic survival. Conclusion Upregulation of PKCη contributes to breast cancer cell growth and targeting either PKCε or PDK1 triggers PKCη downregulation but involves two distinct mechanisms. General significance The status of PKCη may serve as a potential biomarker for breast cancer malignancy.

Original languageEnglish
Pages (from-to)4040-4045
Number of pages6
JournalBiochimica et Biophysica Acta - General Subjects
Volume1830
Issue number8
DOIs
StatePublished - 21 May 2013

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1-Phosphatidylinositol 4-Kinase
Phosphatidylinositols
Protein Kinase C
Cell Survival
Phosphotransferases
Up-Regulation
Cells
Breast Neoplasms
Cell growth
Down-Regulation
protein kinase C kinase
Proteasome Inhibitors
Growth
Protein C Inhibitor
Phorbol Esters
Biomarkers

Keywords

  • Breast cancer
  • Downregulation
  • PDK1
  • PKC

Cite this

@article{58ee34e25aa547b2b25762282c2ce381,
title = "Upregulation of PKCη by PKCε and PDK1 involves two distinct mechanisms and promotes breast cancer cell survival",
abstract = "Background Protein kinase C (PKC) serves as the receptor for tumor-promoting phorbol esters, which are potent activators of conventional (c) and novel (n) PKCs. We recently showed that these activators induced selective upregulation of PKCη in breast cancer cells. The objective of this study is to understand unique regulation of PKCη and its importance in breast cancer. Methods The levels of PKC isozymes were monitored in breast cancer cells following treatment with inhibitors of kinases, proteasome and proteases by Western blotting. PKCε was introduced by adenoviral delivery. PKCη and PDK1 were depleted by siRNA silencing. Cell growth was determined by the MTT or clonal assay. Results The general PKC inhibitors G{\"o} 6983 and bisindolylmaleimide but not cPKC inhibitor G{\"o} 6976 led to substantial PKCη downregulation, which was partly rescued by the introduction of nPKCε. Inhibition of phosphoinositide-dependent kinase-1 (PDK1) by Ly294002 or knockdown of PDK1 also led to downregulation of basal PKCη but had no effect on PKC activator-induced upregulation of PKCη. Proteasome inhibitors blocked PKCη downregulation triggered by PDK1 inhibition/depletion but not by G{\"o} 6983. PKCη level increased in malignant but not in non-tumorigenic or pre-malignant cells in the progressive MCF-10A series associated with activated PDK1, and knockdown of PKCη inhibited breast cancer cell growth and clonogenic survival. Conclusion Upregulation of PKCη contributes to breast cancer cell growth and targeting either PKCε or PDK1 triggers PKCη downregulation but involves two distinct mechanisms. General significance The status of PKCη may serve as a potential biomarker for breast cancer malignancy.",
keywords = "Breast cancer, Downregulation, PDK1, PKC",
author = "Deepanwita Pal and Outram, {Shalini Persaud} and Alakananda Basu",
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Upregulation of PKCη by PKCε and PDK1 involves two distinct mechanisms and promotes breast cancer cell survival. / Pal, Deepanwita; Outram, Shalini Persaud; Basu, Alakananda.

In: Biochimica et Biophysica Acta - General Subjects, Vol. 1830, No. 8, 21.05.2013, p. 4040-4045.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Upregulation of PKCη by PKCε and PDK1 involves two distinct mechanisms and promotes breast cancer cell survival

AU - Pal, Deepanwita

AU - Outram, Shalini Persaud

AU - Basu, Alakananda

PY - 2013/5/21

Y1 - 2013/5/21

N2 - Background Protein kinase C (PKC) serves as the receptor for tumor-promoting phorbol esters, which are potent activators of conventional (c) and novel (n) PKCs. We recently showed that these activators induced selective upregulation of PKCη in breast cancer cells. The objective of this study is to understand unique regulation of PKCη and its importance in breast cancer. Methods The levels of PKC isozymes were monitored in breast cancer cells following treatment with inhibitors of kinases, proteasome and proteases by Western blotting. PKCε was introduced by adenoviral delivery. PKCη and PDK1 were depleted by siRNA silencing. Cell growth was determined by the MTT or clonal assay. Results The general PKC inhibitors Gö 6983 and bisindolylmaleimide but not cPKC inhibitor Gö 6976 led to substantial PKCη downregulation, which was partly rescued by the introduction of nPKCε. Inhibition of phosphoinositide-dependent kinase-1 (PDK1) by Ly294002 or knockdown of PDK1 also led to downregulation of basal PKCη but had no effect on PKC activator-induced upregulation of PKCη. Proteasome inhibitors blocked PKCη downregulation triggered by PDK1 inhibition/depletion but not by Gö 6983. PKCη level increased in malignant but not in non-tumorigenic or pre-malignant cells in the progressive MCF-10A series associated with activated PDK1, and knockdown of PKCη inhibited breast cancer cell growth and clonogenic survival. Conclusion Upregulation of PKCη contributes to breast cancer cell growth and targeting either PKCε or PDK1 triggers PKCη downregulation but involves two distinct mechanisms. General significance The status of PKCη may serve as a potential biomarker for breast cancer malignancy.

AB - Background Protein kinase C (PKC) serves as the receptor for tumor-promoting phorbol esters, which are potent activators of conventional (c) and novel (n) PKCs. We recently showed that these activators induced selective upregulation of PKCη in breast cancer cells. The objective of this study is to understand unique regulation of PKCη and its importance in breast cancer. Methods The levels of PKC isozymes were monitored in breast cancer cells following treatment with inhibitors of kinases, proteasome and proteases by Western blotting. PKCε was introduced by adenoviral delivery. PKCη and PDK1 were depleted by siRNA silencing. Cell growth was determined by the MTT or clonal assay. Results The general PKC inhibitors Gö 6983 and bisindolylmaleimide but not cPKC inhibitor Gö 6976 led to substantial PKCη downregulation, which was partly rescued by the introduction of nPKCε. Inhibition of phosphoinositide-dependent kinase-1 (PDK1) by Ly294002 or knockdown of PDK1 also led to downregulation of basal PKCη but had no effect on PKC activator-induced upregulation of PKCη. Proteasome inhibitors blocked PKCη downregulation triggered by PDK1 inhibition/depletion but not by Gö 6983. PKCη level increased in malignant but not in non-tumorigenic or pre-malignant cells in the progressive MCF-10A series associated with activated PDK1, and knockdown of PKCη inhibited breast cancer cell growth and clonogenic survival. Conclusion Upregulation of PKCη contributes to breast cancer cell growth and targeting either PKCε or PDK1 triggers PKCη downregulation but involves two distinct mechanisms. General significance The status of PKCη may serve as a potential biomarker for breast cancer malignancy.

KW - Breast cancer

KW - Downregulation

KW - PDK1

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U2 - 10.1016/j.bbagen.2013.03.028

DO - 10.1016/j.bbagen.2013.03.028

M3 - Article

VL - 1830

SP - 4040

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JO - Biochimica et Biophysica Acta - General Subjects

JF - Biochimica et Biophysica Acta - General Subjects

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