Estrogen receptor beta (ERβ) is expressed in brain astrocytic tumors and declines with dedifferentiation of the neoplasm

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Abstract

Purpose

Estrogen receptor β (ERβ) is the second identified receptor mediating the effects of estrogen on target tissues. The role of ERβ in cancer pathobiology is largely unknown, because specific antibodies have not been available until recently. Initial studies have shown that ERβ expression declines in breast, ovarian, prostatic, and colon carcinomas. Tamoxifen, a synthetic anti-estrogen compound that is a mixed agonist/antagonist of estrogen receptor α (ERα) and a pure antagonist of ERβ, has moderate beneficial effects in human astrocytic neoplasms. However, most published studies agree that glial tumors do not express ERα. The purpose of this study was to explore the expression of ERβ in astrocytic neoplasms.

Methods

ERβ expression was monitored immunohistochemically in 56 cases of astrocytomas of all grades (grade I-IV) and in adjacent non-neoplastic brain tissue.

Results

Moderate or strong nuclear immunopositivity was obtained in non-neoplastic astrocytes and in low-grade astrocytomas, whereas the majority of high-grade tumors were immunonegative or displayed weak immunoreactivity. The progressive decline in ERβ expression paralleled the increase in tumor grade.

Conclusions

In as much as ERβ is possibly the only ER expressed in astrocytes, its decreased expression may play an important role in astrocytic tumor initiation and in the potential response of glial neoplasms to tamoxifen.

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