Antibodies raised against the extracellular tail of the CCKB/gastrin receptor inhibit gastrin-stimulated signalling

McWilliams, Daniel F.; Grimes, Stephen; Watson, Susan A.

Abstract

Introduction: Gastrin acts to stimulate gastric acid secretion and is an acknowledged growth factor for human gastrointestinal (GI) cancer. The identity of the exact receptor type mediating the growth promoting effects of gastrin in tumours is uncertain. However, the best-characterised gastrin receptor is the CCK receptor type B (CCKB)/gastrin receptor. The anti-GRE1 antibody is a polyclonal, affinity-purified antibody raised against GRE1, a synthetic 21 amino acid peptide homologous to part of the extracellular, N-terminal tail of the CCKB receptor. We have recently proven that GRE1 antiserum specifically localises CCKB receptors on CCKB receptor transfected NIH3T3 cells and human gastrointestinal tumour cells by Western blotting and immunocytochemistry. GRE1 antiserum also inhibits liver invasion in the C170HM2 colorectal liver-metastasis model. Aim: To relate the ability of GRE1 antiserum to displace G17 from CCKB receptors with its impact on cellular transduction effects. Methods: Radioligand binding studies were performed with 125IG17 and Calcium mobilisation studies by use of the fluorescent dye Fura 2-am. Results: GRE1 antiserum competitively displaced 50% radiolabelled gastrin-17 from whole cell NIH3T3 CCKB transfectants at a protein concentration of 250 μg ml-1. GRE1 antiserum did not stimulate calcium ion influx in the transfectant NIH3T3 cells when used at a range of protein concentrations. Pre-incubation with GRE1 antiserum was required to inhibit gastrin-stimulated calcium ion influx. This was found to be concentration-dependent, with inhibition shown at 30 and 5 μg ml-1 but not at 500 ng ml-1 or below. Conclusion: The GRE1 antiserum is specific for the CCKB receptor and may act to inhibit gastrin-stimulated signalling in tumour cells.

Citation

McWilliams, D. F., Grimes, S., & Watson, S. A. (2001). Antibodies raised against the extracellular tail of the CCKB/gastrin receptor inhibit gastrin-stimulated signalling. Regulatory Peptides, 99(2-3), 157-161. https://doi.org/10.1016/S0167-0115%2801%2900245-2

• Journal Article Type: Article
• Acceptance Date: Feb 19, 2001
• Online Publication Date: May 24, 2001
• Publication Date: Jun 15, 2001
• Deposit Date: Jul 31, 2023
• Journal: Regulatory Peptides
• Print ISSN: 0167-0115
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 99
• Issue: 2-3
• Pages: 157-161
• DOI: https://doi.org/10.1016/S0167-0115%2801%2900245-2
• Public URL: https://nottingham-repository.worktribe.com/output/3204297
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0167011501002452?via%3Dihub