Estrogen receptor α (ESR1) overexpression mediated apoptosis in Hep3B cells by binding with SP1 proteins

Chuan Chou Tu, V. Bharath Kumar, Cecilia Hsuan Day, Wei Wen Kuo, Su Peng Yeh, Ray Jade Chen, Chen Rong Liao, Hsiao Yu Chen, Fuu Jen Tsai, Wen Jun Wu, Chih Yang Huang

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22 Citations (Scopus)

Abstract

Previous studies have reported that estrogen receptors (ERs) are expressed in normal human liver, chronic hepatitis, and benign hepatic tumor tissues. However, decreased expression of ERs can be observed in hepatocellular carcinoma (HCC) and the role of ERs in HCC is not fully understood. Thus, the present study aimed to investigate the molecular mechanism induced by the overexpression of ERα (ERα (ESR1)) in Hep3B cells. We first detected the induction of apoptosis in ER-negative Hep3B cells using DNA fragmentation assay and flow cytometry. We found that ERα and ERα plus 17β-estradiol treatment increased apoptosis in Hep3B cells. Additionally, western blotting showed increased expression of active caspase 3 and tumor necrosis factor α (TNFα (TNF)) in ERα-transfected cells. To further understand the importance of SP1-binding sites in the TNFα promoter, ERα-negativeHep3B cellswere co-transfectedwith ERa and a wild-type TNFα plasmid or TNFα with deleted SP1 regions. Deletion of both distant and primal SP1 sites abolished the activity of ERα, and similar results were observed by blocking the expression of SP1 protein using mithramycin (MA). This result indicates that SP1 protein is essential for ERα-activated TNFα promoter activity. Co-immunoprecipitation assay further confirmed the binding interaction between ERα and SP1 in a ligand-dependent manner. In general,we demonstrate that the overexpression of ERαmediates apoptosis in ERα-negative Hep3B cells by the binding of ERα to SP1 protein. Additionally, this ERα-SP1 complex binds to the proximal and distal sites of the TNFα gene promoter and further induces the expression of active caspase 3 in a ligand-dependent manner. 2013 Society for Endocrinology.

Original languageEnglish
Pages (from-to)203-212
Number of pages10
JournalJournal of Molecular Endocrinology
Volume51
Issue number1
DOIs
Publication statusPublished - Jun 3 2013

Keywords

  • Apoptosis
  • Caspase 3
  • ERα
  • Hep3B cells
  • SP1
  • TNFα

ASJC Scopus subject areas

  • Endocrinology
  • Molecular Biology

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  • Cite this

    Tu, C. C., Kumar, V. B., Day, C. H., Kuo, W. W., Yeh, S. P., Chen, R. J., Liao, C. R., Chen, H. Y., Tsai, F. J., Wu, W. J., & Huang, C. Y. (2013). Estrogen receptor α (ESR1) overexpression mediated apoptosis in Hep3B cells by binding with SP1 proteins. Journal of Molecular Endocrinology, 51(1), 203-212. https://doi.org/10.1530/JME-13-0085