Characterization of a bombesin/gastrin-releasing peptide receptor on a human gastric-cancer cell line

✍ Scribed by Shaun R. Preston; Linda F. Woodhouse; Jay Gokhale; Glenn V. Miller; John N. Primrose

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: French
• Weight: 982 KB
• Volume: 57
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/ijc.2910570521

✦ Synopsis

This study examined the expression of receptors of the bombesin (BBS) family in human gastric-cancer cell lines. Of 5 cell lines screened, only one, St42. demonstrated specific binding sites for '251-Ty&BBS, which have been further characterized. This binding was saturable, and temperature-and time-dependent. Scatchard analysis of displacement data performed at 37°C revealed 2 binding sites: a high-affinity, lowcapacity site (& = 0.13 nM, B , , = 1500 sites/cell) and a lower-affinity, higher-capacity site (& = I I nM, B , , = 35,000 sites/cell); the latter was lost when internalization of peptide was prevented, suggesting that it may be an artefact. Displacement assays with gastrin-releasing peptide (GRP) and neuromedin B (NMB) revealed that the receptor was of the GRPpreferring sub-type (GRP ICSO = 0.35 nM; NMB ICs0 = I I 2 nM). Co-valent cross-linking of 1251-Tyl.A-BBS to the receptor demonstrated the presence of a single band corresponding to a molecular weight of 37 to 44 kDa on SDS-PAGE, similar to that of the cloned GRP receptor protein core. G-protein linkage of this receptor was demonstrated by selective inhibition of 12SI-Ty&BBS binding by guanosine nucleotides. The binding of BBS to the receptor resulted in a rise in intracellular calcium. Three of four structurally distinct BBS antagonists bound to the receptor with high affinity, but [DPheI2, Le~'~]-bombesin did not cause any displacement of '251-TyP-BBS even at I 0 mM. The functional significance of GRP receptors on human gastriccancer cells is as yet unknown, but further studies may determine whether such receptors have importance in the therapy of gastric cancer.