title: Inhibition of c-Src blocks oestrogen-induced apoptosis and restores oestrogen-stimulated growth in long-term oestrogen-deprived breast cancer cells.
abstract: OBJECTIVE
  Our publications demonstrate that physiological concentrations of oestrogen (E2) induce endoplasmic reticulum and oxidative stress which finally result in apoptosis in E2-deprived breast cancer cells, MCF-7:5C. c-Src is involved in the process of E2-induced stress. To mimic the clinical administration of c-Src inhibitors, we treated cells with either E2, a c-Src inhibitor PP2, or the combination for 8 weeks to further explore the apoptotic potential of the c-Src inhibitor and E2 on MCF-7:5C cells.
  
  
  METHODS
  Protein levels of receptors and signalling pathways were examined by immunoblotting. Expression of mRNA was detected through real-time polymerase chain reaction (PCR). Cell cycles were analysed by flow cytometry.
  
  
  RESULTS
  Long-term treatment with PP2 alone or E2 alone decreased cell growth. In contrast, a combination of PP2 and E2 blocked apoptosis and the resulting cell line (MCF-7:PF) was unique, as they grew vigorously in culture with physiological levels of E2, which could be blocked by the pure antioestrogen ICI182,780. One major change was that PP2 collaborated with E2 to increase the level of insulin-like growth factor-1 receptor beta (IGF-1Rβ). Blockade of IGF-1Rβ completely abolished E2-stimulated growth in MCF-7:PF cells. Furthermore, combination treatment up-regulated transcription factors, Twist1 and Snail, and repressed E-cadherin expression which made MCF-7:PF cells display a characteristic phenotype of epithelial-mesenchymal transition (EMT).
  
  
  CONCLUSIONS
  These data illustrate the role of the c-Src inhibitor to block E2-induced apoptosis and enhance E2-stimulated growth. Caution must be exercised when considering c-Src inhibitors in clinical trials following the development of acquired resistance to aromatase inhibitors, especially in the presence of the patient's own oestrogen.
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Fan
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA.
authors.forename: Fadeke A
authors.initials: FA
authors.lastname: Agboke
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA.
authors.forename: Russell E
authors.initials: RE
authors.lastname: McDaniel
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA.
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Sweeney
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Zou
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Creswell
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA. Electronic address: vcj2@georgetown.edu.
authors.forename: V Craig
authors.initials: VC
authors.lastname: Jordan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015820:Cadherins / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D000077267:Fulvestrant; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D015151:Immunoblotting; D061986:MCF-7 Cells; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000378:metabolism; D051879:Twist-Related Protein 1 / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C412373:AG 1879; D015820:Cadherins; D004967:Estrogens; D009687:Nuclear Proteins; D011743:Pyrimidines; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D000071250:Snail Family Transcription Factors; C103173:TWIST1 protein, human; D014157:Transcription Factors; D051879:Twist-Related Protein 1; D020032:Tyrphostins; C447031:tyrphostin AG 1024; D000077267:Fulvestrant; D004958:Estradiol; D017526:Receptor, IGF Type 1; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases
keywords: Apoptosis; Breast cancer; Epithelial–mesenchymal transition; Oestrogen; c-Src