Zimmermann U, Fluehmann B, Born W, Fischer J A, Muff R
Research Laboratory for Calcium Metabolism, Department of Orthopaedic Surgery, Zurich, Switzerland.
J Endocrinol. 1997 Dec;155(3):423-31. doi: 10.1677/joe.0.1550423.
Amylin, calcitonin (CT) and calcitonin gene-related peptide (CGRP) share limited structural homology including amino-terminal ring structures linked by a disulfide bridge and amidated carboxy-termini. Here, we have compared [125I]Bolton-Hunter-[Lys1] rat amylin ([125I]amylin) binding and the stimulation of cyclic AMP accumulation by human (h) amylin, hCT and hCGRP-I in the human breast carcinoma cell lines MCF-7 and T47D, which predominantly express hCT1a and hCT1b receptor isoforms (hCTR1a, hCTR1b) at a similar total number of hCT-binding sites. In MCF-7 cells, half-maximal inhibition (IC50) of [125I]amylin binding by human amylin was observed at 3.6 +/- 0.8 nM (n = 6). hCT and hCGRP-I displaced [125I]amylin binding with 22 and 66 times higher IC50. [125I]hCT binding was inhibited by hCT with an IC50 of 8.1 +/- 1.9 nM (n = 5), and human amylin and hCGRP-I were over 100 times less potent. In T47D cells, on the other hand, specific binding of [125I]amylin was not observed, but hCT inhibited [125I]hCT binding with an IC50 of 3.2 +/- 0.4 nM (n = 3), and human amylin and hCGRP-I had over 200 times higher IC50. In MCF-7 cells, half-maximal stimulation (EC50) of cyclic AMP accumulation by human amylin, hCT and hCGRP-I occurred at 1.4 +/- 0.2, 1.7 +/- 0.4 and 6.3 +/- 1.3 nM respectively. In T47D cells, the EC50 of hCT was 0.32 +/- 0.02 nM (n = 3), and 30- and 1900-fold higher with human amylin and hCGRP-I. In conclusion, the expression of hCTR1a and hCTR1b and [125I]hCT binding were indistinguishable in MCF-7 and T47D cells. Yet, [125I]amylin binding was only recognized in MCF-7 cells, consistent with a distinct amylin receptor.
胰淀素、降钙素（CT）和降钙素基因相关肽（CGRP）具有有限的结构同源性，包括通过二硫键连接的氨基末端环结构和酰胺化的羧基末端。在此，我们比较了[125I]博尔顿-亨特-[赖氨酸1]大鼠胰淀素（[125I]胰淀素）在人乳腺癌细胞系MCF-7和T47D中的结合情况，以及人（h）胰淀素、hCT和hCGRP-I对环磷酸腺苷（cAMP）积累的刺激作用。在这些细胞系中，hCT1a和hCT1b受体亚型（hCTR1a、hCTR1b）以相似的hCT结合位点总数为主表达。在MCF-7细胞中，人胰淀素对[125I]胰淀素结合的半数最大抑制（IC50）为3.6±0.8 nM（n = 6）。hCT和hCGRP-I置换[125I]胰淀素结合的IC50分别高22倍和66倍。[125I]hCT结合被hCT抑制，IC50为8.1±1.9 nM（n = 5），而人胰淀素和hCGRP-I的效力低100倍以上。另一方面，在T47D细胞中未观察到[125I]胰淀素的特异性结合，但hCT抑制[125I]hCT结合的IC50为3.2±0.4 nM（n = 3），人胰淀素和hCGRP-I的IC50高200倍以上。在MCF-7细胞中，人胰淀素、hCT和hCGRP-I对cAMP积累的半数最大刺激（EC50）分别为1.4±0.2、1.7±0.4和6.3±1.3 nM。在T47D细胞中，hCT的EC50为0.32±0.02 nM（n = 3），人胰淀素和hCGRP-I的EC50分别高30倍和1900倍。总之，hCTR1a和hCTR1b的表达以及[125I]hCT结合在MCF-7和T47D细胞中无明显差异。然而，[125I]胰淀素结合仅在MCF-7细胞中被识别，这与独特的胰淀素受体一致
