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Troglitazone enhances tamoxifen-induced growth inhibitory activity of MCF-7 cells

Hong-Nu Yu1, Eun-Mi Noh, Young-Rae Lee

  • 1Department of Biochemistry, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju, Jeonbuk, Republic of Korea.

Biochemical and Biophysical Research Communications
|October 7, 2008
PubMed

Insights

Tamoxifen blocks estrogen receptor alpha interference with PPARgamma signaling in breast cancer. Combining tamoxifen with troglitazone enhances growth inhibition in ER(alpha)-positive breast cancer cells.

Area of Science:

  • Oncology
  • Molecular Endocrinology

Background:

  • Peroxisome proliferator-activated receptor gamma (PPARgamma) ligands show promise for cancer therapy.
  • Estrogen receptor alpha (ER(alpha)) negatively impacts PPARgamma signaling in breast cancer, limiting therapeutic potential.
  • ER(alpha) hinders PPARgamma activity, posing a challenge for treating ER(alpha)-positive breast cancers.

Purpose of the Study:

  • To investigate the interaction between ER(alpha) and PPARgamma signaling pathways in breast cancer.
  • To determine if tamoxifen can overcome ER(alpha)-mediated inhibition of PPARgamma activity.
  • To evaluate the combined efficacy of PPARgamma ligands and tamoxifen in ER(alpha)-positive breast cancer cells.

Main Methods:

  • Investigated ER(alpha) inhibition of PPARgamma transactivity.
  • Utilized tamoxifen, an estrogen receptor blocker, to counteract ER(alpha) effects.
  • Assessed the impact of 17-beta-estradiol on PPARgamma ligand-induced activity.
  • Compared the effects of troglitazone on ER(alpha)-positive and ER(alpha)-negative breast cancer cell lines.
  • Evaluated the synergistic effects of combining troglitazone and tamoxifen.

Main Results:

  • ER(alpha) was found to inhibit PPARgamma transactivity.
  • Tamoxifen effectively blocked ER(alpha)-mediated inhibition of PPARgamma signaling.
  • ER(alpha)-positive breast cancer cells showed resistance to the PPARgamma ligand troglitazone.
  • Troglitazone demonstrated greater growth inhibition in ER(alpha)-negative cells compared to ER(alpha)-positive cells.
  • Combination therapy with troglitazone and tamoxifen significantly enhanced growth inhibition in ER(alpha)-positive cells.

Conclusions:

  • ER(alpha) negatively regulates PPARgamma signaling in breast cancer.
  • Tamoxifen can restore PPARgamma pathway function in the presence of ER(alpha).
  • Combination of troglitazone and tamoxifen represents a potentially effective therapeutic strategy for ER(alpha)-positive breast cancer.

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