Steroid hormone receptor studies in melanoma model systems.
The transplantable B-16 melanotic melanoma carried in syngeneic C57Bl/6J female mice and the Syrian hamster melanoma cell line, RPMI 3460, were utilized to determine whether steroid-hormone receptors are present in animal melanomas. In the B-16 melanoma, a cytoplasmic-estrogen receptor is detectable, but there is no evidence for androgen or progestin receptors. Some tumors contain a glucocorticoid-binding macromolecule. Sucrose-density gradient centrifugation of cytosol after incubation with [3H]-estradiol revealed an 8S peak that was suppressed by excess radioinert diethylstilbesterol. Binding varied from 5-35 fmoles per mg cytosol protein. Scatchard analysis of [3H]-estradiol binding in cytosol yielded a single class of high-affinity binding sites; the dissociation constant is 6 x 10(-10) M. The receptor molecule is shown to be estrogen-specific by ligand competition assays. In contrast to B-16 melanoma, no estrogen, androgen, or progestin receptor can be found in the Syrian hamster melanoma cell line. However, a substantial level of specific binding is observed using [3H]-dexamethasone. Sucrose-gradient centrifugation of cytosol from this cell line after incubation with [3H]-dexamethasone revealed a 7S peak that was suppressed by excess radioinert dexamethasone. Scatchard analysis indicated a single class of high-affinity sites with a dissociation constant of 2 x 10(-9) M. Binding levels from 70-610 fmoles per mg cytosol protein were observed. The Syrian hamster melanoma cells also exhibit a biological response to glucocorticoids: Dexamethasone causes both an inhibition of growth and a decrease in final-cell density in these cells.
D000818:Animals; D001667:Binding, Competitive; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D006224:Cricetinae; D003600:Cytosol / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D004958:Estradiol / Q000378:metabolism; D005260:Female; D007700:Kinetics; D008545:Melanoma / Q000378:metabolism*; D008647:Mesocricetus; D051379:Mice; D008810:Mice, Inbred C57BL; D009374:Neoplasms, Experimental / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011987:Receptors, Steroid / Q000378:metabolism*; D012867:Skin / Q000378:metabolism
D011960:Receptors, Estrogen; D011987:Receptors, Steroid; D004958:Estradiol; D003907:Dexamethasone