Estrogen receptors and growth response in cultured human periodontal ligament cells

The periodontal ligament (PDL) is a connective tissue involved in the remodeling process associated with tooth development and positioning. PDL cells grown in culture were analyzed for the capacity to specifically bind steroid hormones and for growth response to estradiol-17 beta. Using [3H]estradiol-17 beta as the ligand, PDL cells in first passage cultures exhibited a specific estrogen binding capacity of 881 fmol/mg cell protein. With [3H]dexamethasone as a ligand, the binding capacity of the glucocorticoid receptor was 143 fmol/mg protein. With [3H]R5020 as a ligand, the progestin receptor exhibited a binding capacity of 5 pmol/mg protein. Scatchard analysis of estradiol binding at 37 degrees revealed a dissociation constant of 2.7 X 10(-9) M, representative of the estrogen receptor. The addition of estradiol-17 beta at concentrations of 10(-9) and 10(-8) M to culture media induced a dose-dependent decrease in growth (DNA content) to 62% and 38% control values, respectively. The addition of the antiestrogens tamoxifen and 4-hydroxytamoxifen at concentrations of 10(-7) and 10(-6) M similarly depressed cell growth. These results show that PDL cells contain high affinity receptors for several steroid hormones and further that these cells are targets for the action of estrogens.