Abstract
Some G protein-coupled receptors (GPCRs) have functional links to cancer biology, yet the manifestation of GPCRs in tumor types is little studied to date. Using a battery of radioligand binding assays for profiling GPCR targets on HeLaS3 cells; high level of specific binding of a 5-HT1A receptor recognition binding agonist [3H]8-OH-DPAT was observed in these cells and characterized. Follow-up studies in competition experiments, several serotonergic compounds and biogenic amine transporter inhibitors competed effectively against [3H]8-OH-DPAT binding with concentration–dependent relationship; 8-OH-DPAT displayed affinity for the labeled amine transporter sites, demonstrated that 5-HT1A receptor agonist [3H]8-OH-DPAT not only binds to intact HeLaS3 cells with high specific binding, but also has multiple binding sites, some of which relate to uptake. [125I]RTI-55 and [3H]paroxetine bound in a saturable fashion to HeLaS3 cells. One or more of the related to 5-HT receptor subtypes was manifested in HeLaS3 cells. It is suggested that HeLaS3 cells contain distinct types of the related to 5-HT receptor system binding sites. These observations could help elucidate the relevance of the 5-HT transporter and receptor systems as well as the possible tumorigenic mechanisms with attendant pharmacological implications in tumor cells.