Gastrin (G17) and N-carboxymethylgastrin (G17-Gly) have been shown to stimulate the growth of colon cancer cells both in vivo and in vitro. The identity of the receptor mediating these effects is controversial. A recent study demonstrated the presence of a low affinity binding site for G17 and G17-Gly on the DLD-1 human colon cancer cell line. The goal of the current study was to further investigate the role of this receptor in mediating the growth-promoting effects of gastrin peptides. Binding of [Leu(15)]G17 and [Leu(15)]G17-Gly to DLD-1 cell membranes in competition with [(3)H]G17-Gly was examined. Binding of [(3)H]cholecystokinin-8 (CCK8) to DLD-1 cell membranes was also assessed. Whole cell binding experiments were carried out using [(125)I-Tyr(12),Leu(15)]G17-Gly. In addition, the ability of [Leu(15)]G17 and [Leu(15)]G17-Gly to stimulate cell growth, as determined by cell counting, was tested. [Leu(15)]G17 and [Leu(15)]G17-Gly competed with [(3)H]G17-Gly at both a high and a low affinity site on DLD-1 membranes. The IC(50) values for [Leu(15)]G17 were 6.0 x 10(-8) M and 6.9 x 10(-6) M while those for [Leu(15)]G17-Gly were 3.2 x 10(-9) M and 4.9 x 10(-6) M. [(3)H]CCK8 did not bind to either site. [Leu(15)]G17-Gly also competed with [(125)I-Tyr(12),Leu(15)]G17-Gly at both a high and a low affinity site on DLD-1 cells with similar affinities as observed with membranes. [Leu(15)]G17 and [Leu(15)]G17-Gly significantly stimulated the growth of DLD-1 cells in a dose-dependent and biphasic manner. The binding profiles of the peptides tested suggest that these sites are different from previously identified wild-type and mutant CCK(1) or CCK(2) receptors.
This research output has an Altmetric Attention Score of 3. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 02 October 2012.
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#12,344,472
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#64,026
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Outputs of similar age from Febs Letters
#61
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