The effect of antiestrogens on TGF-beta-mediated chemotaxis of human breast cancer cells.

Background: In a previous study we compared the influence of several growth factors on cancer cells in culture and observed that transforming growth factor-beta (TGF-beta) enhanced the invasiveness of several breast cancer cell lines. The objective of the present study was to determine the influence of three unique antiestrogens on TGF-beta-mediated chemotaxis of human breast cancer cells. Materials and Methods: The chemotactic activity of TGF-beta was assayed in vitro using collagen TV-coated transwell chambers with either MCF-7 or MDA-MB-231 human breast cancer cells. The cells were pretreated with antiestrogen for 4 days, harvested and placed in the upper transwell chamber. TGF-beta was added to the lower chamber and cell migration and collagenase release were determined following a 6-hour incubation. Results: In this study TGF-beta enhanced the chemotaxis of both cell types with a much greater effect on the MDA-MB-231 cells. However, TGF-beta-mediated chemotaxis of the MCF-7 cells was inhibited by antiestrogen pretreatment while TGF-beta-mediated chemotaxis of the MDA-MB-231 cells was not altered. Further, neither TGF-beta nor antiestrogen treatment altered collagenase release from either cell line. Conclusion: The data demonstrate that pure antiestrogens are capable of inhibiting TGF-beta-mediated chemotaxis in estrogen receptor (ER)-positive breast cancer cells by a mechanism which is independent of collagenase release. Finally, the results of this study suggest a coupling of the TGF-beta and ER signaling pathways and indicate that TGF-beta may be an important therapeutic target for the treatment or inhibition of breast cancer metastasis.