Insulin-like growth factor 1 attenuates antiestrogen- and antiprogestin-induced apoptosis in ER + breast cancer cells by MEK1 regulation of the BH3-only pro-apoptotic protein Bim

Sudharsan Periyasamy Thandavan, Suchreet Takhar, Adam Singer, Michael R. Dohn, William H. Jackson, April E. Welborn, Derek LeRoith, Mario B Marrero, Muthusamy Thangaraju, Shuang Huang, Patricia V Schoenlein

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Introduction: In this pre-clinical in vitro study conducted in estrogen receptor positive (ER+) breast cancer cells, we have characterized the effects of insulin-like growth factor I (IGF-1) on the cytostatic and cytotoxic action of antiestrogen treatment when used as a single agent or in combination with the antiprogestin mifepristone (MIF). Our goal was to identify new molecular targets to improve the efficacy of hormonal therapy in breast cancer patients that have a poor response to hormonal therapy, in part, due to high circulating levels of unbound insulinIGF-1.Methods: IGF-1-mediated effects on cytostasis and apoptotic cell death were determined with cell counts conducted in the presence and absence of trypan blue; enzyme-linked immunosorbent assays to determine the intracellular levels of cleaved cytokeratin 18, a marker of epithelial cancer cell apoptosis; and immunoblot analysis to determine the levels of cleaved poly-ADP ribose polymerase (PARP) and lamin A that result from caspase-dependent apoptosis. Cytotoxicity was further characterized by determination of the levels of reactive oxygen species (ROS) and the percent of mitochondrial membrane depolarization in cell populations treated with the different hormones in the presence and absence of IGF-1. Small molecule inhibitors of the dual-specificity protein kinase MEK1, MEK1 siRNA, Bim siRNA, and vectors overexpressing MEK1 wild type and mutant, dominant negative cDNA were used to identify key IGF-1 downstream prosurvival effectors.Results: IGF-1, at physiologically relevant levels, blocked the cytotoxic action(s) of the antiestrogens 4-hydroxytamoxifen (4-OHT) and tamoxifen (TAM) when used as single agents or in combination with the antiprogestin MIF. The antiapoptotic action of IGF-1 was mediated primarily through the action of MEK1. MEK1 expression reduced the levels of ROS and mitochondrial membrane depolarization induced by the hormonal treatments via a mechanism that involved the phosphorylation and proteasomal turnover of the proapoptotic BH3-only Bcl-2 family member Bim. Importantly, small-molecule inhibitors of MEK1 circumvented the prosurvival action of IGF-1 by restoring Bim to levels that more effectively mediated apoptosis in ER + breast cancer cells.Conclusion: his study provides strong support for the use of MEK1 inhibitors in combination with hormonal therapy to effectively affect cytostasis and activate a Bim-dependent apoptotic pathway in ER + breast cancer cells. We discuss that MEK1 blockade may be a particularly effective treatment for women with high circulating levels of IGF-1, which have been correlated to a poor prognosis.

Original languageEnglish (US)
Article numberR52
JournalBreast Cancer Research
Volume14
Issue number2
DOIs
StatePublished - Mar 19 2012

Fingerprint

Apoptosis Regulatory Proteins
Estrogen Receptor Modulators
Somatomedins
Insulin-Like Growth Factor I
Apoptosis
Breast Neoplasms
Mifepristone
Mitochondrial Membranes
Small Interfering RNA
Reactive Oxygen Species
Therapeutics
MAP Kinase Kinase 1
Lamin Type A
Keratin-18
Trypan Blue
Poly(ADP-ribose) Polymerases
Cytostatic Agents
Tamoxifen
Caspases
Estrogen Receptors

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

Insulin-like growth factor 1 attenuates antiestrogen- and antiprogestin-induced apoptosis in ER + breast cancer cells by MEK1 regulation of the BH3-only pro-apoptotic protein Bim. / Periyasamy Thandavan, Sudharsan; Takhar, Suchreet; Singer, Adam; Dohn, Michael R.; Jackson, William H.; Welborn, April E.; LeRoith, Derek; Marrero, Mario B; Thangaraju, Muthusamy; Huang, Shuang; Schoenlein, Patricia V.

In: Breast Cancer Research, Vol. 14, No. 2, R52, 19.03.2012.

Research output: Contribution to journalArticle

Periyasamy Thandavan, Sudharsan ; Takhar, Suchreet ; Singer, Adam ; Dohn, Michael R. ; Jackson, William H. ; Welborn, April E. ; LeRoith, Derek ; Marrero, Mario B ; Thangaraju, Muthusamy ; Huang, Shuang ; Schoenlein, Patricia V. / Insulin-like growth factor 1 attenuates antiestrogen- and antiprogestin-induced apoptosis in ER + breast cancer cells by MEK1 regulation of the BH3-only pro-apoptotic protein Bim. In: Breast Cancer Research. 2012 ; Vol. 14, No. 2.
@article{df11dc83d18c4929a59b83336e710bb1,
title = "Insulin-like growth factor 1 attenuates antiestrogen- and antiprogestin-induced apoptosis in ER + breast cancer cells by MEK1 regulation of the BH3-only pro-apoptotic protein Bim",
abstract = "Introduction: In this pre-clinical in vitro study conducted in estrogen receptor positive (ER+) breast cancer cells, we have characterized the effects of insulin-like growth factor I (IGF-1) on the cytostatic and cytotoxic action of antiestrogen treatment when used as a single agent or in combination with the antiprogestin mifepristone (MIF). Our goal was to identify new molecular targets to improve the efficacy of hormonal therapy in breast cancer patients that have a poor response to hormonal therapy, in part, due to high circulating levels of unbound insulinIGF-1.Methods: IGF-1-mediated effects on cytostasis and apoptotic cell death were determined with cell counts conducted in the presence and absence of trypan blue; enzyme-linked immunosorbent assays to determine the intracellular levels of cleaved cytokeratin 18, a marker of epithelial cancer cell apoptosis; and immunoblot analysis to determine the levels of cleaved poly-ADP ribose polymerase (PARP) and lamin A that result from caspase-dependent apoptosis. Cytotoxicity was further characterized by determination of the levels of reactive oxygen species (ROS) and the percent of mitochondrial membrane depolarization in cell populations treated with the different hormones in the presence and absence of IGF-1. Small molecule inhibitors of the dual-specificity protein kinase MEK1, MEK1 siRNA, Bim siRNA, and vectors overexpressing MEK1 wild type and mutant, dominant negative cDNA were used to identify key IGF-1 downstream prosurvival effectors.Results: IGF-1, at physiologically relevant levels, blocked the cytotoxic action(s) of the antiestrogens 4-hydroxytamoxifen (4-OHT) and tamoxifen (TAM) when used as single agents or in combination with the antiprogestin MIF. The antiapoptotic action of IGF-1 was mediated primarily through the action of MEK1. MEK1 expression reduced the levels of ROS and mitochondrial membrane depolarization induced by the hormonal treatments via a mechanism that involved the phosphorylation and proteasomal turnover of the proapoptotic BH3-only Bcl-2 family member Bim. Importantly, small-molecule inhibitors of MEK1 circumvented the prosurvival action of IGF-1 by restoring Bim to levels that more effectively mediated apoptosis in ER + breast cancer cells.Conclusion: his study provides strong support for the use of MEK1 inhibitors in combination with hormonal therapy to effectively affect cytostasis and activate a Bim-dependent apoptotic pathway in ER + breast cancer cells. We discuss that MEK1 blockade may be a particularly effective treatment for women with high circulating levels of IGF-1, which have been correlated to a poor prognosis.",
author = "{Periyasamy Thandavan}, Sudharsan and Suchreet Takhar and Adam Singer and Dohn, {Michael R.} and Jackson, {William H.} and Welborn, {April E.} and Derek LeRoith and Marrero, {Mario B} and Muthusamy Thangaraju and Shuang Huang and Schoenlein, {Patricia V}",
year = "2012",
month = "3",
day = "19",
doi = "10.1186/bcr3153",
language = "English (US)",
volume = "14",
journal = "Breast Cancer Research",
issn = "1465-5411",
publisher = "BioMed Central",
number = "2",

}

TY - JOUR

T1 - Insulin-like growth factor 1 attenuates antiestrogen- and antiprogestin-induced apoptosis in ER + breast cancer cells by MEK1 regulation of the BH3-only pro-apoptotic protein Bim

AU - Periyasamy Thandavan, Sudharsan

AU - Takhar, Suchreet

AU - Singer, Adam

AU - Dohn, Michael R.

AU - Jackson, William H.

AU - Welborn, April E.

AU - LeRoith, Derek

AU - Marrero, Mario B

AU - Thangaraju, Muthusamy

AU - Huang, Shuang

AU - Schoenlein, Patricia V

PY - 2012/3/19

Y1 - 2012/3/19

N2 - Introduction: In this pre-clinical in vitro study conducted in estrogen receptor positive (ER+) breast cancer cells, we have characterized the effects of insulin-like growth factor I (IGF-1) on the cytostatic and cytotoxic action of antiestrogen treatment when used as a single agent or in combination with the antiprogestin mifepristone (MIF). Our goal was to identify new molecular targets to improve the efficacy of hormonal therapy in breast cancer patients that have a poor response to hormonal therapy, in part, due to high circulating levels of unbound insulinIGF-1.Methods: IGF-1-mediated effects on cytostasis and apoptotic cell death were determined with cell counts conducted in the presence and absence of trypan blue; enzyme-linked immunosorbent assays to determine the intracellular levels of cleaved cytokeratin 18, a marker of epithelial cancer cell apoptosis; and immunoblot analysis to determine the levels of cleaved poly-ADP ribose polymerase (PARP) and lamin A that result from caspase-dependent apoptosis. Cytotoxicity was further characterized by determination of the levels of reactive oxygen species (ROS) and the percent of mitochondrial membrane depolarization in cell populations treated with the different hormones in the presence and absence of IGF-1. Small molecule inhibitors of the dual-specificity protein kinase MEK1, MEK1 siRNA, Bim siRNA, and vectors overexpressing MEK1 wild type and mutant, dominant negative cDNA were used to identify key IGF-1 downstream prosurvival effectors.Results: IGF-1, at physiologically relevant levels, blocked the cytotoxic action(s) of the antiestrogens 4-hydroxytamoxifen (4-OHT) and tamoxifen (TAM) when used as single agents or in combination with the antiprogestin MIF. The antiapoptotic action of IGF-1 was mediated primarily through the action of MEK1. MEK1 expression reduced the levels of ROS and mitochondrial membrane depolarization induced by the hormonal treatments via a mechanism that involved the phosphorylation and proteasomal turnover of the proapoptotic BH3-only Bcl-2 family member Bim. Importantly, small-molecule inhibitors of MEK1 circumvented the prosurvival action of IGF-1 by restoring Bim to levels that more effectively mediated apoptosis in ER + breast cancer cells.Conclusion: his study provides strong support for the use of MEK1 inhibitors in combination with hormonal therapy to effectively affect cytostasis and activate a Bim-dependent apoptotic pathway in ER + breast cancer cells. We discuss that MEK1 blockade may be a particularly effective treatment for women with high circulating levels of IGF-1, which have been correlated to a poor prognosis.

AB - Introduction: In this pre-clinical in vitro study conducted in estrogen receptor positive (ER+) breast cancer cells, we have characterized the effects of insulin-like growth factor I (IGF-1) on the cytostatic and cytotoxic action of antiestrogen treatment when used as a single agent or in combination with the antiprogestin mifepristone (MIF). Our goal was to identify new molecular targets to improve the efficacy of hormonal therapy in breast cancer patients that have a poor response to hormonal therapy, in part, due to high circulating levels of unbound insulinIGF-1.Methods: IGF-1-mediated effects on cytostasis and apoptotic cell death were determined with cell counts conducted in the presence and absence of trypan blue; enzyme-linked immunosorbent assays to determine the intracellular levels of cleaved cytokeratin 18, a marker of epithelial cancer cell apoptosis; and immunoblot analysis to determine the levels of cleaved poly-ADP ribose polymerase (PARP) and lamin A that result from caspase-dependent apoptosis. Cytotoxicity was further characterized by determination of the levels of reactive oxygen species (ROS) and the percent of mitochondrial membrane depolarization in cell populations treated with the different hormones in the presence and absence of IGF-1. Small molecule inhibitors of the dual-specificity protein kinase MEK1, MEK1 siRNA, Bim siRNA, and vectors overexpressing MEK1 wild type and mutant, dominant negative cDNA were used to identify key IGF-1 downstream prosurvival effectors.Results: IGF-1, at physiologically relevant levels, blocked the cytotoxic action(s) of the antiestrogens 4-hydroxytamoxifen (4-OHT) and tamoxifen (TAM) when used as single agents or in combination with the antiprogestin MIF. The antiapoptotic action of IGF-1 was mediated primarily through the action of MEK1. MEK1 expression reduced the levels of ROS and mitochondrial membrane depolarization induced by the hormonal treatments via a mechanism that involved the phosphorylation and proteasomal turnover of the proapoptotic BH3-only Bcl-2 family member Bim. Importantly, small-molecule inhibitors of MEK1 circumvented the prosurvival action of IGF-1 by restoring Bim to levels that more effectively mediated apoptosis in ER + breast cancer cells.Conclusion: his study provides strong support for the use of MEK1 inhibitors in combination with hormonal therapy to effectively affect cytostasis and activate a Bim-dependent apoptotic pathway in ER + breast cancer cells. We discuss that MEK1 blockade may be a particularly effective treatment for women with high circulating levels of IGF-1, which have been correlated to a poor prognosis.

UR - http://www.scopus.com/inward/record.url?scp=84862795381&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84862795381&partnerID=8YFLogxK

U2 - 10.1186/bcr3153

DO - 10.1186/bcr3153

M3 - Article

VL - 14

JO - Breast Cancer Research

JF - Breast Cancer Research

SN - 1465-5411

IS - 2

M1 - R52

ER -