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Enhancement of Apoptotic and Autophagic Induction by a Novel Synthetic C-1 Analogue of 7-deoxypancratistatin in Human Breast Adenocarcinoma and Neuroblastoma Cells with Tamoxifen
19:44

Enhancement of Apoptotic and Autophagic Induction by a Novel Synthetic C-1 Analogue of 7-deoxypancratistatin in Human Breast Adenocarcinoma and Neuroblastoma Cells with Tamoxifen

Published on: May 30, 2012

Expression of active Akt protects against tamoxifen-induced apoptosis in MCF-7 Cells

Incheol Shin1, Carlos L Arteaga

  • 1Department of Cancer Biology, Vanderbilt-Ingram Comprehensive Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6307, USA.

IUBMB Life
|November 7, 2006
PubMed

Insights

Constitutively active Akt (AktDD) promotes breast cancer cell proliferation and estrogen receptor transcription. AktDD overexpression also reduces sensitivity to tamoxifen, suggesting Akt confers resistance to anti-estrogen therapies.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Endocrinology

Background:

  • Tamoxifen is a widely used anti-estrogen therapy for estrogen receptor-positive breast cancer.
  • The Akt signaling pathway plays a crucial role in cell growth, proliferation, and survival.
  • Understanding mechanisms of tamoxifen resistance is critical for improving breast cancer treatment.

Purpose of the Study:

  • To investigate the impact of constitutive active Akt (AktDD) expression on tamoxifen's effects in MCF-7 human breast cancer cells.
  • To determine how AktDD affects estrogen receptor (ER) mediated transcription and cell proliferation.

Main Methods:

  • Forced expression of constitutively active Akt (AktDD) in MCF-7 cells.
  • Luciferase assays to measure estradiol-dependent ER transcription.
  • Cell proliferation assays in charcoal-stripped serum medium with estradiol.
  • Cell cycle analysis using flow cytometry.
  • Assessment of tamoxifen-induced apoptosis.

Main Results:

  • AktDD overexpression increased phosphorylation of GSK3beta, a downstream Akt substrate.
  • MCF-7 cells overexpressing AktDD (MCF-7 AktDD) exhibited a >2-fold increase in estradiol-dependent ER transcription compared to control cells.
  • MCF-7 AktDD cells showed enhanced proliferation and a shift in cell cycle from G1 to S phase.
  • AktDD overexpression attenuated tamoxifen-mediated apoptosis.

Conclusions:

  • Constitutively active Akt signaling can enhance estrogen receptor activity and promote breast cancer cell proliferation.
  • Akt signaling confers resistance to tamoxifen's anti-proliferative and pro-apoptotic effects.
  • Targeting the Akt pathway may be a strategy to overcome tamoxifen resistance in breast cancer.

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