The role of tyrosine kinase Etk/Bmx in EGF-induced apoptosis of MDA-MB-468 breast cancer cells

Kai Yun Chen, Li Ming Huang, Hsing Jien Kung, David K. Ann, Hsiu Ming Shih

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Etk/Bmx, a member of the Tec family of tyrosine kinases, mediates various signaling pathways and confers several cellular functions. In the present study, we have explored the functional role of Etk in mediating EGF-induced apoptosis, using MDA-MB-468 cell line as a model. We first demonstrated that EGF treatment induces Etk tyrosine phosphorylation in both HeLa and MDA-MB-468 cells. Overexpression of Etk by recombinant adeno-virus in MDA-MB-468 cells potentiates the extent of EGF-induced cell apoptosis. The observed Etk-enhanced MDA-MB-468 cell apoptosis is associated with the Stat1 activation, as demonstrated by electrophoresis mobility shift assays and reporter gene assays. By contrast, a kinase domain deletion mutant EtkΔK, functioning as a dominant-negative mutant, ameliorates EGF-induced Stat1 activation and apoptosis in MDA-MB-468 cells. To explore whether the activated Etk alone is sufficient for inducing apoptosis, a conditionally activated Etk (ΔEtk-ER), a chimeric fusion protein of PH domain-truncated Etk and ligand-binding domain of estrogen receptor, was introduced into MDA-MB-468 cells. Upon β-estradiol ligand activation, the ΔEtk-ER could stimulate Stat1 activity and confer cell apoptosis independent of EGF treatment. Taken together, our findings indicate that Etk is a downstream signaling molecule of EGF receptor and suggest that Etk activation is essential for transducing the EGF-induced apoptotic signaling.

Original languageEnglish
Pages (from-to)1854-1862
Number of pages9
JournalOncogene
Volume23
Issue number10
DOIs
Publication statusPublished - Mar 11 2004
Externally publishedYes

Fingerprint

Epidermal Growth Factor
Protein-Tyrosine Kinases
Apoptosis
Breast Neoplasms
Ligands
Electrophoretic Mobility Shift Assay
Reporter Genes
Epidermal Growth Factor Receptor
Estrogen Receptors
Tyrosine
Electrophoresis
Estradiol
Phosphotransferases
Phosphorylation
Viruses
Cell Line

Keywords

  • EGF-induced apoptosis
  • Etk kinase
  • Stat1 activation

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research
  • Genetics

Cite this

The role of tyrosine kinase Etk/Bmx in EGF-induced apoptosis of MDA-MB-468 breast cancer cells. / Chen, Kai Yun; Huang, Li Ming; Kung, Hsing Jien; Ann, David K.; Shih, Hsiu Ming.

In: Oncogene, Vol. 23, No. 10, 11.03.2004, p. 1854-1862.

Research output: Contribution to journalArticle

Chen, Kai Yun ; Huang, Li Ming ; Kung, Hsing Jien ; Ann, David K. ; Shih, Hsiu Ming. / The role of tyrosine kinase Etk/Bmx in EGF-induced apoptosis of MDA-MB-468 breast cancer cells. In: Oncogene. 2004 ; Vol. 23, No. 10. pp. 1854-1862.
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abstract = "Etk/Bmx, a member of the Tec family of tyrosine kinases, mediates various signaling pathways and confers several cellular functions. In the present study, we have explored the functional role of Etk in mediating EGF-induced apoptosis, using MDA-MB-468 cell line as a model. We first demonstrated that EGF treatment induces Etk tyrosine phosphorylation in both HeLa and MDA-MB-468 cells. Overexpression of Etk by recombinant adeno-virus in MDA-MB-468 cells potentiates the extent of EGF-induced cell apoptosis. The observed Etk-enhanced MDA-MB-468 cell apoptosis is associated with the Stat1 activation, as demonstrated by electrophoresis mobility shift assays and reporter gene assays. By contrast, a kinase domain deletion mutant EtkΔK, functioning as a dominant-negative mutant, ameliorates EGF-induced Stat1 activation and apoptosis in MDA-MB-468 cells. To explore whether the activated Etk alone is sufficient for inducing apoptosis, a conditionally activated Etk (ΔEtk-ER), a chimeric fusion protein of PH domain-truncated Etk and ligand-binding domain of estrogen receptor, was introduced into MDA-MB-468 cells. Upon β-estradiol ligand activation, the ΔEtk-ER could stimulate Stat1 activity and confer cell apoptosis independent of EGF treatment. Taken together, our findings indicate that Etk is a downstream signaling molecule of EGF receptor and suggest that Etk activation is essential for transducing the EGF-induced apoptotic signaling.",
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