Low content of estrogen receptors in human giant cell tumors of bone
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M Ishibe1, Y Ishibe, T Ishibashi
1Department of Orthopaedics, Hokkaido University, School of Medicine, Sapporo, Japan.
Abstract:
We tried to identify estrogen receptors (ERs) in human giant cell tumors of bone. Samples from eight patients were used for biochemical and immunohistochemical studies using [125I]17 beta-estradiol and monoclonal antibody against the human ER. Estradiol binding sites were detected in seven cases out of eight. The dissociation constant of the higher affinity binding site was 0.5 nM. Nonlabeled 17 beta-estradiol and synthetic estrogen, diethyl-stilbestrol, inhibited the binding of labeled 17 beta-estradiol to the tumor cytosol, while dexamethasone did not inhibit the binding. Using a monoclonal antibody. Western blotting identified bands of M(r) 68,000 and 59,000. 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 immunohistochemically.
Insights
Estrogen receptors (ERs) were found in most human giant cell tumors of bone using biochemical methods. However, these ERs were at levels too low for detection with immunohistochemistry.
Area of Science:
- Oncology
- Endocrinology
- Bone Biology
Background:
- Giant cell tumors of bone are a distinct bone neoplasm.
- The role of estrogen receptors (ERs) in giant cell tumors of bone is not well understood.
Purpose of the Study:
- To investigate the presence and characteristics of estrogen receptors (ERs) in human giant cell tumors of bone.
Main Methods:
- Biochemical assays using [125I]17 beta-estradiol for radioligand binding.
- Immunohistochemical analysis utilizing a monoclonal antibody against human ER.
- Western blotting to identify ER protein bands.
Main Results:
- Estradiol binding sites were detected in 7 out of 8 tumor samples.
- A high-affinity binding site with a dissociation constant of 0.5 nM was identified.
- Western blotting revealed ER protein bands at M(r) 68,000 and 59,000.
- Immunohistochemistry failed to detect ERs in any of the examined cases.
Conclusions:
- Human giant cell tumors of bone possess low levels of estrogen receptors.
- These ERs are detectable biochemically but not by standard immunohistochemical methods.
- Further research is needed to elucidate the functional significance of these low-level ERs in tumor biology.