Possible involvement of protein kinase C-ε in phorbol estex-induced growth inhibition of human lymphoblastic cells

R. Mihalik, Gyöngyi Farkas, L. Kópper, Miklós Benczúr, A. Faragó

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Sustained activation of members of the protein kinase C (PKC) family is known to influence the growth and differentiation of various cell types, however, the specific roles for individual isoforms mediating these cellular events have yet to be elucidated. Activation of PKC by phorbol esters leads to growth inhibition in certain cell lines. The HT58 human B lymphoblastic cell may serve as a cellular model system to investigate the participation of individual isoforms in the initial events of growth arrest induced by phorbol ester. Determination of cell cycle and investigation of apoptosis were performed by flow cytometric measurements. Phorbol ester-induced translocation and down-regulation of the conventional α, β and the novel ε isoforms of PKC were demonstrated by Western blot analysis. At lower concentrations (0.5 ng/ml) phorbol myristate acetate (PMA) stimulated a G1 arrest with retention of viability in the human HT58 B lymphoblastic cell. The protein kinase inhibitor staurosporine at a concentration of 25 nM did not significantly alter HT58 cell viability. However, staurosporine (25 nM) induced apoptosis in cells preincubated for 4 hr with 0.5-1.0 ng/ml PMA. The translocation of PKC-ε was observed within 30 min exposure to 0.5 ng/ml PMA. After a 4 hr treatment, evidence for down-regulation and an altered phosphorylation state of PKC-ε was seen. In contrast, the conventional α and β isoforms were practically unaffected by this PMA treatment. At higher PMA concentrations (50 ng/ml) the α and β isoforms showed a significant down-regulation. The preferential alterations in PKC-ε observed under the conditions required for PMA to influence the growth and survival of HT58 cells suggest a role for the Ca2+-independent ε isoform in mediating the initial events of the phorbol ester stimulated cellular responses.

Original languageEnglish
Pages (from-to)925-933
Number of pages9
JournalInternational Journal of Biochemistry and Cell Biology
Volume28
Issue number8
DOIs
Publication statusPublished - Aug 1996

Fingerprint

Tetradecanoylphorbol Acetate
Protein Kinase C
Protein Isoforms
Cells
Phorbol Esters
Growth
Staurosporine
Down-Regulation
Cell Survival
Chemical activation
Apoptosis
Phosphorylation
Flow measurement
Protein Kinase Inhibitors
phorbol
Cell Differentiation
Cell Cycle
Western Blotting
Cell Line

Keywords

  • Apoptosis B cell lymphoma
  • Growth inhibition
  • Phorbol ester
  • Protein kinase C-ε isoform

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology

Cite this

@article{7f1af56d1e824ac2acc9646a6f7af4f9,
title = "Possible involvement of protein kinase C-ε in phorbol estex-induced growth inhibition of human lymphoblastic cells",
abstract = "Sustained activation of members of the protein kinase C (PKC) family is known to influence the growth and differentiation of various cell types, however, the specific roles for individual isoforms mediating these cellular events have yet to be elucidated. Activation of PKC by phorbol esters leads to growth inhibition in certain cell lines. The HT58 human B lymphoblastic cell may serve as a cellular model system to investigate the participation of individual isoforms in the initial events of growth arrest induced by phorbol ester. Determination of cell cycle and investigation of apoptosis were performed by flow cytometric measurements. Phorbol ester-induced translocation and down-regulation of the conventional α, β and the novel ε isoforms of PKC were demonstrated by Western blot analysis. At lower concentrations (0.5 ng/ml) phorbol myristate acetate (PMA) stimulated a G1 arrest with retention of viability in the human HT58 B lymphoblastic cell. The protein kinase inhibitor staurosporine at a concentration of 25 nM did not significantly alter HT58 cell viability. However, staurosporine (25 nM) induced apoptosis in cells preincubated for 4 hr with 0.5-1.0 ng/ml PMA. The translocation of PKC-ε was observed within 30 min exposure to 0.5 ng/ml PMA. After a 4 hr treatment, evidence for down-regulation and an altered phosphorylation state of PKC-ε was seen. In contrast, the conventional α and β isoforms were practically unaffected by this PMA treatment. At higher PMA concentrations (50 ng/ml) the α and β isoforms showed a significant down-regulation. The preferential alterations in PKC-ε observed under the conditions required for PMA to influence the growth and survival of HT58 cells suggest a role for the Ca2+-independent ε isoform in mediating the initial events of the phorbol ester stimulated cellular responses.",
keywords = "Apoptosis B cell lymphoma, Growth inhibition, Phorbol ester, Protein kinase C-ε isoform",
author = "R. Mihalik and Gy{\"o}ngyi Farkas and L. K{\'o}pper and Mikl{\'o}s Bencz{\'u}r and A. Farag{\'o}",
year = "1996",
month = "8",
doi = "10.1016/1357-2725(96)00020-9",
language = "English",
volume = "28",
pages = "925--933",
journal = "International Journal of Biochemistry and Cell Biology",
issn = "1357-2725",
publisher = "Elsevier Limited",
number = "8",

}

TY - JOUR

T1 - Possible involvement of protein kinase C-ε in phorbol estex-induced growth inhibition of human lymphoblastic cells

AU - Mihalik, R.

AU - Farkas, Gyöngyi

AU - Kópper, L.

AU - Benczúr, Miklós

AU - Faragó, A.

PY - 1996/8

Y1 - 1996/8

N2 - Sustained activation of members of the protein kinase C (PKC) family is known to influence the growth and differentiation of various cell types, however, the specific roles for individual isoforms mediating these cellular events have yet to be elucidated. Activation of PKC by phorbol esters leads to growth inhibition in certain cell lines. The HT58 human B lymphoblastic cell may serve as a cellular model system to investigate the participation of individual isoforms in the initial events of growth arrest induced by phorbol ester. Determination of cell cycle and investigation of apoptosis were performed by flow cytometric measurements. Phorbol ester-induced translocation and down-regulation of the conventional α, β and the novel ε isoforms of PKC were demonstrated by Western blot analysis. At lower concentrations (0.5 ng/ml) phorbol myristate acetate (PMA) stimulated a G1 arrest with retention of viability in the human HT58 B lymphoblastic cell. The protein kinase inhibitor staurosporine at a concentration of 25 nM did not significantly alter HT58 cell viability. However, staurosporine (25 nM) induced apoptosis in cells preincubated for 4 hr with 0.5-1.0 ng/ml PMA. The translocation of PKC-ε was observed within 30 min exposure to 0.5 ng/ml PMA. After a 4 hr treatment, evidence for down-regulation and an altered phosphorylation state of PKC-ε was seen. In contrast, the conventional α and β isoforms were practically unaffected by this PMA treatment. At higher PMA concentrations (50 ng/ml) the α and β isoforms showed a significant down-regulation. The preferential alterations in PKC-ε observed under the conditions required for PMA to influence the growth and survival of HT58 cells suggest a role for the Ca2+-independent ε isoform in mediating the initial events of the phorbol ester stimulated cellular responses.

AB - Sustained activation of members of the protein kinase C (PKC) family is known to influence the growth and differentiation of various cell types, however, the specific roles for individual isoforms mediating these cellular events have yet to be elucidated. Activation of PKC by phorbol esters leads to growth inhibition in certain cell lines. The HT58 human B lymphoblastic cell may serve as a cellular model system to investigate the participation of individual isoforms in the initial events of growth arrest induced by phorbol ester. Determination of cell cycle and investigation of apoptosis were performed by flow cytometric measurements. Phorbol ester-induced translocation and down-regulation of the conventional α, β and the novel ε isoforms of PKC were demonstrated by Western blot analysis. At lower concentrations (0.5 ng/ml) phorbol myristate acetate (PMA) stimulated a G1 arrest with retention of viability in the human HT58 B lymphoblastic cell. The protein kinase inhibitor staurosporine at a concentration of 25 nM did not significantly alter HT58 cell viability. However, staurosporine (25 nM) induced apoptosis in cells preincubated for 4 hr with 0.5-1.0 ng/ml PMA. The translocation of PKC-ε was observed within 30 min exposure to 0.5 ng/ml PMA. After a 4 hr treatment, evidence for down-regulation and an altered phosphorylation state of PKC-ε was seen. In contrast, the conventional α and β isoforms were practically unaffected by this PMA treatment. At higher PMA concentrations (50 ng/ml) the α and β isoforms showed a significant down-regulation. The preferential alterations in PKC-ε observed under the conditions required for PMA to influence the growth and survival of HT58 cells suggest a role for the Ca2+-independent ε isoform in mediating the initial events of the phorbol ester stimulated cellular responses.

KW - Apoptosis B cell lymphoma

KW - Growth inhibition

KW - Phorbol ester

KW - Protein kinase C-ε isoform

UR - http://www.scopus.com/inward/record.url?scp=0030220253&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030220253&partnerID=8YFLogxK

U2 - 10.1016/1357-2725(96)00020-9

DO - 10.1016/1357-2725(96)00020-9

M3 - Article

VL - 28

SP - 925

EP - 933

JO - International Journal of Biochemistry and Cell Biology

JF - International Journal of Biochemistry and Cell Biology

SN - 1357-2725

IS - 8

ER -