Endothelin-1 promotes steroidogenesis and stimulates protooncogene expression in transformed murine Leydig cells.
The effects of endothelin-1 (ET-1), a potent vasoconstrictor and mitogen to various cell types, on proliferation and differentiated functions of the murine Leydig tumor cell line MA-10 were investigated. Kinetic binding experiments at room temperature showed that [125I] ET-1 bound to MA-10 cells and reached equilibrium in 2 h. The data from competitive binding experiments yielded an apparent single class of high affinity binding sites characterized by a Kd and maximum binding capacity of 1 nM and 59 fmol/10(6) cells, respectively. For steroidogenic assays, cells were incubated with ET-1 (1 pM to 1 microM) and with epidermal growth factor (10 ng/ml) for 4 h at 37 C, and the progesterone levels in the medium were measured by RIA. Like epidermal growth factor, ET-1 caused about a 6-fold increase in progesterone production. ET-1 also enhanced the transient expression of the protooncogenes c-jun and c-myc by 3- and 2-fold, respectively. For proliferation studies, ET-1 (1 pM to 1 microM) was added to quiescent MA-10 cells for 24 h, and cell counts were performed; no increase in cell number was observed. The results of this study demonstrate that MA-10 cells possess high affinity binding sites for ET-1 and that ET-1 stimulates progesterone production and protooncogene expression, but not mitosis in this cell line.
Ergul
A
A
Department of Biochemistry, University of Miami School of Medicine, Florida 33101.
Glassberg
M K
MK
Majercik
M H
MH
Puett
D
D
D000818:Animals; D015152:Blotting, Northern; D002461:Cell Line, Transformed; D004305:Dose-Response Relationship, Drug; D016232:Endothelins / Q000378:metabolism* / Q000494:pharmacology*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D016758:Genes, jun / Q000187:drug effects*; D016259:Genes, myc / Q000187:drug effects*; D007700:Kinetics; D007984:Leydig Cell Tumor; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D011374:Progesterone / Q000096:biosynthesis*; D017466:Receptors, Endothelin / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D016232:Endothelins; D017466:Receptors, Endothelin; D011374:Progesterone; D004815:Epidermal Growth Factor