Response of normal and oncogene-transformed human mammary epithelial cells to transforming growth factor β1 (TGF-β1): Lack of growth-inhibitory effect on cells expressing the simian virus 40 large-t antigen
✍ Scribed by Fulvio Basolo; Lisa Fiore; Fortunato Ciardiello; Simonetta Calvo; Gabriella Fontanini; Pier Giulio Conaldi; Antonio Toniolo
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- French
- Weight
- 825 KB
- Volume
- 56
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
The relationship between the expression of selected oncogenes having different modes of action and the loss of the capacity t o respond in vitro to transforming growth factor+ I (TGF-P I) was analyzed in human mammary epithelial cells (MEC). Primary MEC cultures from healthy donors and the spontaneously immortalized MCF-IOA cell line were used as normal controls. Various assays (employing both complete and chemically defined media) were used: short-term DNA synthesis, long-term cell proliferation under anchorage-dependent and -independent conditions, expression of surface-differentiation molecules. Whereas primary MEC and the MCF-IOA cell line were fully responsive to the growth-inhibitory activity of TGF-PI under different test conditions, MEC transformed by c-Ha-ras, c-erbB2, int-2, or SV40-large-T antigen were not inhibited by TGF-PI in a short-term DNA-synthesis assay. However, in anchorage-dependent conditions TGF-f3 I inhibited the proliferation of all lines investigated, with the exception of SV40-T-antigen-transformed MEC. The colony-formation assay in soft agar revealed that all lines, but not those expressing the int-2 or the SV40-T-antigen genes, were inhibited by TGF-PI. Neutralizing antibody to TGF-P had no significant effects on oncogene-transformed lines, suggesting that the endogenous production of an active form of this growth factor is not a major determinant in MEC transformation by the oncogenes investigated. The only observed effect of TGF-pl on selected surfacedifferentiation molecules was that normal MEC produced increased levels of the human milk fat globule antigen-I. Thus it appears that the response of MEC to TGF-PI is consistently attenuated by the insertion of a variety of oncogenes and that it is abolished only by the expression of the SV40-large-T antigen. Whereas no single in vitro assay was capable of accurately reflecting the actual responsiveness of different lines, the growth-curve assay in anchorage-dependent conditions was the best single predictive test.