Characterization, in some human breast cancer cell lines, of gastrin-releasing peptide-like receptors which are absent in normal breast epithelial cells
✍ Scribed by Sylvie Giacchetti; Christiane Gauvillé; Patricia De Crémoux; Laurent Bertin; Philippe Berthon; Jean-Pierre Abita; Franck Cuttitta; Fabien Calvo
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- French
- Weight
- 736 KB
- Volume
- 46
- Category
- Article
- ISSN
- 0020-7136
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
The binding of ^125^I‐Tyr^4^ bombesin was investigated on plasma membranes of 8 human breast cancer cell lines and 2 long‐term cultures of normal human breast epithelial cells. Scatchard plots were compatible with high‐affinity, single‐site class of receptors in 3 cell lines (K~D~ of 0.75 ± 10^−9^ and 10^−9^ M, B~max~ of 0.75 ± 10^−13^ and 9.7 ± 10^−13^ M/mg protein in MDAMB231 and in T47D cells, respectively) while no binding was observed in 5 other cell lines and normal epithelial cells. The neuropeptide and its structural analogues (natural or synthetic) inhibited the binding of ^125^I‐Tyr^4^ bombesin in the following order of potency: gastrin‐releasing peptide (GRP, EC~50~ = 1.7 ± ^−10^ M) > BIM 26159 > bombesin, Tyr^4^ bombesin > BIM 26147 > litorin > neuromedin C. In contrast, ^125^I‐Tyr^4^ bombesin binding was not displaced by neuromedin B, somatostatin, bradykinin and insulin. In agreement with our binding data, SDS‐PAGE of the complex ^125^I‐Tyr^4^ bombesin‐receptor covalently linked by ethylene glycol‐bis succinimidyl succinate (EGS) identified after autoradiography a single band with a molecular weight of 75,000, which disappeared in the presence of bombesin in excess. No transcription of either GRP or neuromedin B mRNA could be shown in tumor or normal cells. Exogenous gastrin‐releasing peptide had no effect on growth of the cell lines when a serum‐free medium was used, implicating that in breast cancer cell lines this receptor does not mediate growth but has a functional role.