Enhanced endothelin ET(B) receptor down-regulation in human tumor cells

• Published in: European journal of pharmacology 2000-05, Vol.396 (1), p.19-22
• Main Authors: Drimal, J, Drimal, Jr, J, Drimal, D
• Format: Article
• Language: English
• Subjects: Cells, Cultured; Down-Regulation - drug effects; Down-Regulation - genetics; Endothelin-1 - metabolism; Endothelins - pharmacology; Fibroblasts - metabolism; HeLa Cells; Humans; Kinetics; Ligands; Membranes - metabolism; Neoplasms - genetics; Neoplasms - metabolism; Peptide Fragments - pharmacology; Receptor, Endothelin B; Receptors, Endothelin - biosynthesis; Receptors, Endothelin - drug effects; Receptors, Endothelin - genetics
• ISSN: 0014-2999
• DOI: 10.1016/S0014-2999(00)00198-9

The characteristics of specific binding of human [125I]Tyr(13)-endothelin-(1-21), [125I]-Tyr(13)-Suc-[Glu(9),Ala(11, 15)]-endothelin-(8-21), ([125I]IRL-1620) and endothelin ET(A) receptor antagonist [125I]Tyr(3)-(N-[(hexahydro-1H-azepin-1-yl)carbonyl]-L-Leu]-1Me )-D-Trp ([125I]PD151242) (number of sites and their affinity) and proliferation responses to exogenous endothelin receptor agonists (endothelin-1 and the endothelin ET(B) receptor-selective, truncated N-acetyl-[Ala(11,15)]-endothelin-(6-21) analogue BQ3020) were determined in cultured human fibroblasts and in tumorigenic HeLa cells. The cells were pre-incubated with equimolar concentrations of human endothelin-1 or its truncated analogue BQ3020. After pre-incubation (2 h), both peptides induced down-regulation of surface-membrane endothelin-1 receptors. This process was specific for endothelin ET(B) receptors and was much more intensive in tumorigenic cells. BQ3020, acting mostly through its C-terminus, induced nearly maximal endothelin ET(B) receptor down-regulation in HeLa cells. Staurosporine, a wide spectrum protein kinase inhibitor, significantly reduced, and N-[N-[N-[2, 6-dimethyl-1piperidinyl)carbonyl]-4-Me-L-Leu]-1-(methoxycarbonyl)- D-t ryptophanyl]-D-norleucine (BQ788), an endothelin ET(B) receptor antagonist, attenuated the down-regulation of endothelin receptors induced by endothelin receptor agonists. The down-regulation of endothelin ET(B) receptors was prevented by pre-incubation of the cells with the lysosomal enzyme blocker chloroquine. The endothelin-1-induced cell proliferation was attenuated by pre-incubation of the cells with the non-selective endothelin receptor antagonist Ac-D-10,11-dihydro-5H-dibenzo[a,d] cycloheptene-glycine-3,3-D-diphenyl-Ala-Leu-Asp-Ile-Ile-Trp (PD142893) and it was only partially reduced by the endothelin ET(A) receptor-selective endothelin antagonist PD151242.