title: Identification of gene regulation patterns underlying both oestrogen- and tamoxifen-stimulated cell growth through global gene expression profiling in breast cancer cells.
abstract: OBJECTIVE
  A c-Src inhibitor blocks oestrogen (E2)-induced stress and converts E2 responses from inducing apoptosis to growth stimulation in E2-deprived breast cancer cells. A reprogrammed cell line, MCF-7:PF, results in a functional oestrogen receptor (ER). We addressed the question of whether the selective ER modulator 4-hydroxytamoxifen (4-OHT) could target ER to prevent E2-stimulated growth in MCF-7:PF cells.
  
  
  METHODS
  Expression of mRNA was measured through real-time RT-PCR. Global gene expression profile was analysed through microarray. Transcriptome profiles were screened by RNA-sequencing.
  
  
  RESULTS
  Unexpectedly, both 4-OHT and E2 stimulated cell growth in a concentration-dependent manner. Expression profiling showed a remarkable overlap in genes regulated in the same direction by E2 and 4-OHT. Pathway enrichment analysis of the 280 genes commonly deregulated in MCF-7:PF cells by 4-OHT and E2 revealed functions mainly related to membrane, cytoplasm and metabolic processes. Further analysis of 98 genes up-regulated by both 4-OHT and E2 uncovered a significant enrichment in genes associated with membrane remodelling, cytoskeleton reorganisation, cytoplasmic adapter proteins, cytoplasm organelle proteins and related processes. 4-OHT was more potent than E2 in up-regulating some membrane remodelling molecules, such as EHD2, FHL2, HOMER3 and RHOF. In contrast, 4-OHT acted as an antagonist to inhibit expression of the majority of enriched membrane-associated genes in wild-type MCF-7 cells.
  
  
  CONCLUSIONS
  Long-term selection pressure has changed the cell population responses to 4-OHT. Membrane-associated signalling is critical for 4-OHT-stimulated cell growth in MCF-7:PF cells. This study provides a rationale for the further investigation of target therapy for tamoxifen resistant patients.
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington DC 20057, United States.
authors.forename: Ping
authors.initials: P
authors.lastname: Fan
authors.affiliation: Computational Biology Division, The Translational Genomics Research Institute, Phoenix, AZ 85004, United States.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Cunliffe
authors.affiliation: Department of Medicine, Division of Oncology, The Genome Institute, Washington University, St. Louis, MO 63108, United States.
authors.forename: Obi L
authors.initials: OL
authors.lastname: Griffith
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington DC 20057, United States.
authors.forename: Fadeke A
authors.initials: FA
authors.lastname: Agboke
authors.affiliation: Computational Biology Division, The Translational Genomics Research Institute, Phoenix, AZ 85004, United States.
authors.forename: Pilar
authors.initials: P
authors.lastname: Ramos
authors.affiliation: Biomedical Engineering Department, Oregon Health and Science University, Portland, OR 97239, United States.
authors.forename: Joe W
authors.initials: JW
authors.lastname: Gray
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington DC 20057, United States. Electronic address: vcj2@georgetown.edu.
authors.forename: V Craig
authors.initials: VC
authors.lastname: Jordan
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D004967:Estrogens / Q000737:chemistry*; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D061986:MCF-7 Cells; D020411:Oligonucleotide Array Sequence Analysis; D011960:Receptors, Estrogen / Q000378:metabolism; D020845:Selective Estrogen Receptor Modulators / Q000627:therapeutic use; D017423:Sequence Analysis, RNA; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000737:chemistry*
chemical_list: D004967:Estrogens; D011960:Receptors, Estrogen; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen; C016601:afimoxifene
keywords: Gene expression profiling; Membrane-associated molecules; Oestrogen; Tamoxifen