Characterization of 5-HT transporter and receptor system in HeLaS3 cells by [3H]8-OH-DPAT and other serotonergic ligands

[H-3]8-OH-DPAT is a selective ligand for labeling 5-HT1A receptor sites. In competition binding experiments, we found that classic biogenic amine transporter inhibitors displaced [H-3]8-OH-DPAT binding at its high-affinity binding sites in HeLaS3 cells. [I-125]RTI-55 and [H-3]paroxetine are known to specifically label amine transporter sites, and this was observed in our cells. Displacement studies showed that 8-OH-DPAT displayed affinity in a dose-dependent manner for the labeled amine transporter sites. These data suggest that [H-3]8-OH-DPAT binds to amine uptake sites in HeLaS3 cells. A variety of drugs targeting different classes of receptors did not significantly affect [H-3]8-OH-DPAT binding. Moreover, we determined the specific binding effects of various serotonergic ligands (i.e. [I-125]cyanopindolol, [H-3]ketanserin/[H-3]mesulergine, [H-3]GR-65630, [H-3]GR-113808 and [H-3]LSD) that specifically labeled 5-HT1, 5-HT2, 5HT(3), 5-HT4 and 5-HT5-7 receptors, respectively. It is suggested that HeLaS3 cells contain distinct types of the related to 5-HT receptor recognition binding sites. These observations could help elucidate the relevant characteristics of different types of 5-HT receptors and 5-HT membrane transporters in tumor cells and their role in tumorigenesis. (C) 2010 Elsevier Inc. All rights reserved.