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Demonstration of basic fibroblast growth factor high and low affinity binding sites in human breast cancer cell lines
J P Peyrat1, H Hondermark, M M Louchez
1Laboratoire d'Endocrinologie Expérimentale, Centre Oscar Lambret, Lille, France.
Abstract:
The binding characteristics of basic fibroblast growth factor (bFGF) to membranes prepared from four human breast cancer cell lines (BT-20; MCF-7; MDA-MB-231; T-47D) have been investigated. Scatchard analyses of competition experiments indicate one class of specific binding sites in MCF-7 and T-47D cells, and two classes of specific binding sites in BT-20 and MDA-MB-231 cells. The presence of high affinity sites was demonstrated in each cell type. These results have been confirmed using saturation experiments. Chemical crosslinking of labeled bFGF in breast cancer cell lines followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed one specific complex with a relative molecular mass of about 85,000. A second class of lower affinity binding sites was detected only in the two hormone-independent cell lines. bFGF stimulation of proliferation has also been demonstrated in MCF-7, T-47D, and BT-20, but not in MDA-MB-231, which has a high proliferation activity without the addition of growth factors. These suggest that the presence of bFGF specific binding sites in human breast cancer cell membranes is a necessary but not sufficient condition for exogenous bFGF growth stimulation of these cells; they also suggest that FGF plays a role in breast cancer.
Insights
Basic fibroblast growth factor (bFGF) binds to specific sites on human breast cancer cells. The number and affinity of these sites vary, influencing cell proliferation and suggesting a role for FGF in breast cancer.
Area of Science:
- Oncology
- Cell Biology
- Biochemistry
Background:
- Basic fibroblast growth factor (bFGF) is implicated in various cellular processes, including proliferation.
- Understanding bFGF interactions with cancer cells is crucial for targeted therapies.
Purpose of the Study:
- To investigate the binding characteristics of bFGF to membranes of human breast cancer cell lines.
- To determine the relationship between bFGF binding sites and cell proliferation.
Main Methods:
- Scatchard analysis and saturation experiments were used to characterize bFGF binding sites.
- Chemical crosslinking and SDS-PAGE identified bFGF-receptor complexes.
- Cell proliferation assays assessed the effect of bFGF stimulation.
Main Results:
- MCF-7 and T-47D cells exhibited one class of specific bFGF binding sites, while BT-20 and MDA-MB-231 cells showed two classes.
- High-affinity binding sites were present in all tested cell lines.
- A specific bFGF-receptor complex of approximately 85,000 Da was detected.
- Lower affinity sites were found in hormone-independent cell lines (BT-20, MDA-MB-231).
- bFGF stimulated proliferation in MCF-7, T-47D, and BT-20 cells, but not in MDA-MB-231 cells.
Conclusions:
- Specific bFGF binding sites on breast cancer cell membranes are necessary but not sufficient for exogenous bFGF-induced growth stimulation.
- FGF likely plays a significant role in the development and progression of breast cancer.