LOW CONTENT OF ESTROGEN-RECEPTORS IN HUMAN GIANT-CELL TUMORS OF BONE

We tried to identify estrogen receptors (ERs) in human giant cell tumo rs of bone. Samples from eight patients were used for biochemical and immunohistochemical studies using [I-125] 17beta-estradiol and monoclo nal antibody against the human ER. Estradiol binding sites were detect ed in seven cases out of eight. The dissociation constant of the highe r affinity binding site was 0.5 nM. Nonlabeled 17beta-estradiol and sy nthetic estrogen, diethylstilbestrol, inhibited the binding of labeled 17beta-estradiol to the tumor cytosol, while dexamethasone did not in hibit the binding. Using a monoclonal antibody, Western blotting ident ified bands of M(r) 68000 and 59000. No ERs were observed in any case examined immunohistochemically. These results suggest that human giant cell tumors of bone have a low level of ERs that cannot be detected i mmunohistochemically.