Ligand-independent antiapoptotic function of estrogen receptor-β in lung cancer cells

Guang Feng Zhang, Naveena Yanamala, Kira L. Lathrop, Lin Zhang, Judith Klein-Seetharaman, Harish Srinivas

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

Recent studies have demonstrated the presence of estrogen receptor (ER)β in the mitochondria in various cell types and tissues, but the exact function of this localization remains unclear. In this study, we have examined the function of mitochondrial ERβ in non-small-cell lung cancer (NSCLC) cells. Down-regulation of ERβ by short hairpin RNA constructs sensitized NSCLC cells to various apoptosis-inducing agents such as cisplatin, taxol, and etoposide. The increased growth inhibition and induction of apoptosis in ERβ-knockdown cells was observed irrespective of estrogen treatment, suggesting a ligand-independent role of ERβ in regulating the intrinsic apoptotic pathway. Further, ERβ from the mitochondrial fraction physically interacted with the proapoptotic protein Bad, in a ligand-independent manner. Glutathione-S-transferase pull-down assays and molecular modeling studies revealed that the DNA-binding domain and hinge region of ERβ, and the BH3 domain of Bad were involved in these interactions. Further investigations revealed that ERβ inhibited Bad function by disrupting Bad-Bcl-X L and Bad-Bcl-2 interactions. Reintroduction of ERβ in the mitochondria of ERβ knockdown cells reversed their sensitivity to cisplatin. Overall, our results demonstrate a ligand-independent role of ERβ in regulating apoptosis, revealing a novel function for ERβ in the mitochondria.

Original languageEnglish (US)
Pages (from-to)1737-1747
Number of pages11
JournalMolecular Endocrinology
Volume24
Issue number9
DOIs
StatePublished - Sep 2010
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology

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