title: Modulation of tumorigenesis and oestrogen receptor-alpha expression by cell culture conditions in a stem cell-derived breast epithelial cell line.
abstract: BACKGROUND
  The common phenotypes of cancer and stem cells suggest that cancers arise from stem cells. Oestrogen is one of the few most important determinants of breast cancer, as shown by several lines of convincing evidence. We have previously reported a human breast epithelial cell type (Type 1 HBEC) with stem cell characteristics and ER alpha (oestrogen receptor alpha) expression. A tumorigenic cell line, M13SV1R2, was developed from this cell type after SV40 (simian virus 40) large T-antigen transfection and X-ray irradiation. The cell line, however, was not responsive to oestrogen for cell growth or tumour development. In the present study, we tested the hypothesis that deprivation of growth factors and hormones may change the tumorigenicity and oestrogen response of this cell line.
  
  
  RESULTS
  The M13SV1R2 cells lost their tumorigenicity after culturing in a growth factor/hormone-deprived medium for >10 passages (referred to as R2d cells) concomitant with the expression of two tumour suppressor genes, namely those coding for maspin and alpha 6 integrin. However, these cells acquired oestrogen responsiveness in cell growth and tumour development. By immunocytochemistry, Western blotting and flow cytometry analysis, oestrogen treatment of R2d cells was found to induce many important effects related to breast carcinogenesis, namely: (i) the emergence of a subpopulation of cells expressing CD44+/high/CD24-/low breast tumour stem cell markers; (ii) the induction of EMT (epithelial-to-mesenchymal transition); (iii) the acquisition of metastatic ability; and (iv) the expression of COX-2 (cyclo-oxygenase-2) through a CD44-mediated mechanism.
  
  
  CONCLUSIONS
  An oestrogen-responsive cell line with ER alpha and CD44+/CD24-/low expression can be derived from breast epithelial stem cells. The tumorigenicity and oestrogen response of these cells could depend on the cell culture conditions. The findings of this study have implications in regard to the origins of (1) ER alpha-positive breast cancers, (2) CD44+/CD24-/low breast tumour stem cells and (3) the metastatic ability of breast cancer.
authors.affiliation: Graduate Institute of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Kai-Hung
authors.initials: KH
authors.lastname: Wang
authors.forename: An-Pei
authors.initials: AP
authors.lastname: Kao
authors.forename: Chia-Cheng
authors.initials: CC
authors.lastname: Chang
authors.forename: Jau-Nan
authors.initials: JN
authors.lastname: Lee
authors.forename: Chee-Yin
authors.initials: CY
authors.lastname: Chai
authors.forename: Ming-Feng
authors.initials: MF
authors.lastname: Hou
authors.forename: Cheng-Min
authors.initials: CM
authors.lastname: Liu
authors.forename: Eing-Mei
authors.initials: EM
authors.lastname: Tsai
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D015197:Carcinogenicity Tests; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism*; D018929:Cell Culture Techniques; D054337:Cell Dedifferentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D051546:Cyclooxygenase 2 / Q000187:drug effects / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D004967:Estrogens / Q000172:deficiency / Q000494:pharmacology; D005260:Female; D016147:Genes, Tumor Suppressor / Q000187:drug effects; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000172:deficiency; D009362:Neoplasm Metastasis / Q000503:physiopathology; D014411:Neoplastic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; C497483:CD44 protein, human; D003470:Culture Media; D047628:Estrogen Receptor alpha; D004967:Estrogens; D018960:Hyaluronan Receptors; D036341:Intercellular Signaling Peptides and Proteins; D051546:Cyclooxygenase 2