Modulation of tumorigenesis and oestrogen receptor-alpha expression by cell culture conditions in a stem cell-derived breast epithelial cell line.
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.
Wang
Kai-Hung
KH
Graduate Institute of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
Kao
An-Pei
AP
Chang
Chia-Cheng
CC
Lee
Jau-Nan
JN
Chai
Chee-Yin
CY
Hou
Ming-Feng
MF
Liu
Cheng-Min
CM
Tsai
Eing-Mei
EM
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*
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