Modulation of tumorigenesis and oestrogen receptor‐α expression by cell culture conditions in a stem cell‐derived breast epithelial cell line

Abstract

Background information. 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 ERα (oestrogen receptor α) 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 α6 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.Conclusion. An oestrogen-responsive cell line with ERα 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) ERα-positive breast cancers, (2) CD44 + /CD24 −/low breast tumour stem cells and (3) the metastatic ability of breast cancer.

Analysis of the in�vitro effects of di‑(2‑ethylhexyl) phthalate exposure on human uterine leiomyoma cells

“…The results of this study indicate that continual exposure to DEHP may induce HIF-1α and COX-2 expression and may enhance proliferation ability, which is consistent with previous similar studies (49,50). Elevated expression of inflammatory proteins could elicit various effects, including the promotion of tumor progression, by inducing proliferation and resistance to apoptosis (51). HIF-1α and COX-2 expression was indicated to be increased by DEHP treatment, suggesting that DEHP may serve a critical function in inflammation of human leiomyoma cells.…”

Comparative study of human eutopic and ectopic endometrial mesenchymal stem cells and the development of an in vivo endometriotic invasion model

“…The methods for flow cytometric analysis of gene expression are described in our recent publication (43).…”

Increasing CD44+/CD24- tumor stem cells, and upregulation of COX-2 and HDAC6, as major functions of HER2 in breast tumorigenesis

“…However, few major mechanisms have been reported. First, HER2 could regulate cyclooxygenase (COX)-2 [12] and elevated COX-2 could induce many tumorigenic effects such as tumor invasion, angiogenesis, suppression of host immunity, resistance to apoptosis [13-15] and epithelial to mesenchymal transition (EMT) [16]. Second, p185 HER2/neu could phosphorylate and activate major signalling pathways such as phosphatidylinositol-3-kinase (PI3K/Akt) and mitogen-activated protein kinase (MAPK) pathways and promote cell survival, tumor growth and metastasis [10,17,18].…”

“…These immortal cells (M13SV1) can be further transformed to weakly tumorigenic (M13SV1R2) and highly tumorigenic cells (M13SV1R2N1) by successive X-ray irradiation and ectopic expression of C-erbB2/neu [28]. Recently, we found that M13SV1R2 cells became non-tumorigenic after growing in a growth factor/hormone-deprived medium for >10 passages (referred to as R2d cells) [16]. Unlike M13SV1R2 cells, these R2d cells contain CD44 + /CD24 - cells previously identified as breast cancer stem cells [29] and were responsive to estrogen for cell growth and tumor development [16].…”

“…Recently, we found that M13SV1R2 cells became non-tumorigenic after growing in a growth factor/hormone-deprived medium for >10 passages (referred to as R2d cells) [16]. Unlike M13SV1R2 cells, these R2d cells contain CD44 + /CD24 - cells previously identified as breast cancer stem cells [29] and were responsive to estrogen for cell growth and tumor development [16]. In this study, we developed M13SV1R2N1 under the same growth factor/hormone-deprived condition (referred to as R2N1d cells).…”