Altered restriction pattern of the putative DNA binding domain of estrogen receptor or related genes in primary human meningiomas

Expression of estrogen receptors alpha and beta in human meningiomas

The predominance of meningiomas in females, their accelerated growth during the luteal phase of the menstrual cycle and during pregnancy; and the association between meningiomas and breast cancer has led to a number of studies examining the potential role of steroids on the growth of meningiomas. It is generally agreed that the majority of meningiomas possess the progesterone and androgen receptor. There are numerous discrepancies in the literature among the results for estrogen receptor (ER). The aim of this study was to examine the expression of ER-alpha mRNA and the recently described novel ER, ER-beta in meningiomas. Using reverse transcription and polymerase chain reaction (RT-PCR) Southern blot analysis thirty-four meningiomas were examined for the presence of ER-alpha and ER-beta. Forty-four percent of meningiomas showed a strong band for ER-beta mRNA and sixty-eight percent of meningiomas showed a strong band for ER-alpha mRNA. The involvement of ER-beta in meningioma biology should be examined further, given the differences in the ER-alpha and ER-beta gene products.

Androgen receptor expression in meningiomas

The predominance of meningiomas in females, the accelerated growth of these tumors during the luteal phase of the menstrual cycle and during pregnancy, and the association between meningiomas and breast cancer have led to a number of studies examining the potential role of steroids in the growth of meningiomas. The possibility that androgens play a role in meningioma proliferation has been suggested by a small number of investigators. The aim of this study was to examine the expression of androgen receptor messenger ribonucleic acid (mRNA) and correlate it using immunochemistry with the nuclear localization of androgen receptor in a large number of meningiomas. Thirty-nine meningiomas were examined by Northern blot analysis for the presence of measurable amounts of androgen receptor mRNA and eight of these were analyzed by immunohistochemistry for receptor protein. Sixty-seven percent of the meningiomas expressed androgen receptor mRNA. There was a marked predominance of women among the patients whose tumors expressed androgen receptor; 69% were women and 31% were men. The immunohistochemical data correlated with Northern blot analysis of mRNA. The staining was predominantly nuclear, suggesting that the androgen receptor resides in a location that can activate gene expression.

Estrogen receptors: new perspectives in breast cancer management

The imbalance between proliferative and differentiative estrogenic effect, caused by quantitative and qualitative alteration of the estrogen receptor (ER) expression, may play a determinant role in mammary neoplastic transformation. Our studies demonstrate that ER levels are significantly higher in human mammary neoplastic tissues when compared to perineoplastic tissues and that increased ER expression is associated with ER gene hypomethylation. During progressive multifactorial carcinogenesis, ER overexpression may represent an early step in neoplastic transformation. In fact, high levels of ER represent good markers of differentiation and can predict the likelihood of benefiting from anti-estrogen therapy. Nevertheless, about 35% of ER-positive breast cancers are resistant to endocrine therapy and 10% of ER-negative tumors behave as hormone-sensitive tumors. Recent studies on ER mRNA variants, which naturally occur in human breast tumors, demonstrated mutations, deletions and alternative splicings, yielding deletions of exons 3, 4, 5 and 7. ER variants exhibited altered functions or changed the responsiveness to hormonal therapy. Analysis of these variants could be a useful parameter to better predict tumor responsiveness to anti-estrogen therapy. Recently, a regain of hormonal responsiveness by ER-negative breast cancer cells has been reported following ER gene transfection. However, estradiol treatment inhibits rather than stimulates cell growth as well as the metastatic and invasive potential of the ER gene transduced cells. Transfer of the ER gene may be considered as a new therapeutic approach in the management of hormone-independent breast cancer.

Expression of androgen and progesterone receptors in primary human meningiomas

Meningiomas are common brain tumors that show a predilection for females and become more aggressive during pregnancy and menses. The existence of gender-specific hormone receptors in meningiomas has long been a matter of controversy; the recent cloning of androgen, estrogen, and progesterone receptors has facilitated their direct evaluation. The authors have demonstrated the expression of androgen and progesterone receptor messenger ribonucleic acid and protein product in nine primary human meningiomas by Northern blot analysis. Cellular localization was achieved by in situ hybridization analysis. Estrogen receptor expression was not detected. Normal adult meninges were shown to express very low levels of both androgen and progesterone receptors.