A study of dexamethasone receptor protein in human gliomas

Steroid hormone receptors in astrocytic neoplasms

The presence of specific steroid hormone-binding receptors has been correlated with the clinical response to hormonal therapy in a number of different neoplasias, including breast and prostate cancer. In this article, we investigated the expression of the androgen, estrogen, glucocorticoid, and progesterone receptor messenger ribonucleic acid (mRNA) and protein in a number of astrocytic neoplasms of various histological grades. Androgen and glucocorticoid receptor mRNA were detected in all astrocytic neoplasms examined, regardless of histological subtype. In contrast, progesterone receptor mRNA was observed more frequently in high-grade tumors than in low-grade tumors. Estrogen receptor mRNA was undetectable in all astrocytic tumors examined. These studies suggest a possible adjunct clinical use of hormonal therapy for the treatment of astrocytomas. Specific antagonists and agonists may allow the modulation of the growth of these tumors. Development of this body of knowledge may lead to the development of better treatment for these aggressive tumors.

Characteristics and biological role of steroid hormone receptors in neuroepithelial tumors

Tissue samples from 57 patients with neuroepithelial tumors (25 glioblastomas, 18 anaplastic astrocytomas, and 14 astrocytomas) were analyzed in order to evaluate the presence of estrogen, progesterone, glucocorticoid, and androgen receptors. Glucocorticoid- and androgen-specific binding proteins were present in 38.6% and 21.6% of the cases, respectively. Only a few tumors showed estrogen or progesterone receptors. A correlation was found between grade of anaplasia, patient's sex and age, and presence of glucocorticoid and androgen receptors. The biological role of these two receptors was investigated in 10 primary cell cultures derived from neuroepithelial tumors. For this purpose, dexamethasone and testosterone were added to culture medium at different concentrations (from 50 to 0.016 micrograms/ml). A significant stimulation of the cell growth was observed in four of five glucocorticoid receptor-positive cultures when dexamethasone in doses ranging from 2 to 0.016 microgram/ml was added to the culture. No modulation of the growth was observed in glucocorticoid receptor-negative cultures at the same doses. Higher dexamethasone doses induced a significant decrease of the growth index independently from the glucocorticoid receptor status. All of the cultures tested for testosterone activity were negative for androgen receptors. This hormone induced an inhibition of the growth index at doses ranging from 50 to 0.4 micrograms/ml. The data suggest that neuroepithelial tumors contain specific glucocorticoid and androgen binding proteins. Glucocorticoid receptors modulate the growth of cultured neuroepithelial tumors in the presence of different concentrations of dexamethasone.

Effects of prostaglandin and leukotriene inhibitors on the growth of human glioma spheroids

Established cell-lines of human glioma origin were cultured as multicellular spheroids or as monolayers. Volume growth and 3H-thymidine labelling were analysed for the spheroids after continuous exposure to drugs interfering with the release of arachidonic acid and the production of prostaglandins and leukotrienes. Comparative measurements were made on monolayer cultures. The cyclo-oxygenase inhibitor indomethacin enhanced growth at intermediate concentrations (0.5-5.0 micrograms/ml) but reduced growth at 50 micrograms/ml. The dual cyclo-oxygenase and lipoxygenase inhibitor ketoprofen had a significant inhibitory effect on growth and cell proliferation of spheroids at high concentration (50 micrograms/ml). The weak lipoxygenase inhibitor NDGA (quinone-form) decreased growth whereas the strong lipoxygenase inhibitor NDGA (hydroquinone-form) did not reduce growth rate but significantly decreased cell proliferation. Quinacrine reduced the spheroid growth rate although dexamethasone had no effects. Thus, inhibitors of the arachidonic acid cascade had growth inhibitory effects in the spheroid tumour model as well as in cells cultured as monolayers.

Glucocorticoid receptors in glioblastoma multiforme: a new approach to antineoplastic glucocorticoid therapy

Glucocorticoid receptors were measured in tissue samples from 12 patients with glioblastoma multiforme. The receptor was found in all patients. The concentration of glucocorticoid receptor was found to be high in the periphery of the tumour, low in the surrounding brain tissue and low in the central part of the tumour in 6 of the patients. The possible role of the glucocorticoid receptor distribution in relation to growth regulation is discussed. A decreasing receptor concentration found at reoperation in two patients indicates a possible antineoplastic effect of high dose methylprednisolone pulse therapy on glucocorticoid receptor positive glioblastomas.

The antineoplastic effect of methylprednisolone pulse therapy in two patients with glucocorticoid receptor-positive glioblastoma multiforme

Glucocorticoids in high concentrations inhibit in vitro the growth rate of glioblastoma multiforme. This presupposes the presence of glucocorticoid receptors in the cytoplasma. Glucocorticoid receptor positive patients with histological glioblastoma multiforme were postoperatively treated with high dose methylprednisolone pulse therapy during which CT-scanning initially demonstrated tumor regression. One patient's tumor size was unchanged after 24 weeks, whereas in the other patient, the tumor size after decreasing for 1 month began increasing again. The survival rate, at the present 15 and 10 months, without irradiation therapy and the decreasing glucocorticoid receptor concentrations at reoperations indicate an antineoplastic effect by continuous high-dose glucocorticoid pulse therapy.

Steroid hormone receptors in human meningiomas, gliomas and brain metastases

Progestin, estrogen, androgen, glucocorticoid as well as mineralocorticoid receptors (PR, ER, AR, GR and MR, respectively) were all evaluated with specific synthetic radioligands (biochemical assays) in 25 meningiomas, 9 gliomas and 4 brain metastases. In meningiomas the main steroid hormone receptors appeared to be the progestin receptor, present in 24/25 cases (mean level: 7 105 fmol/gT) and the androgen receptor, present in 23/25 cases (mean level: 2 265 fmol/gT). Progestin receptor levels were found to be significantly lower in meningiomas of the fibroblastic subtype whereas none of the steroid hormone receptors were detected in the anaplastic case. On the other hand, glucocorticoid receptor levels were related to the preoperative glucocorticoid therapy. In gliomas only estrogen receptors (2/9 cases) and especially androgen receptors (8/9 cases) were noticeable: the latter seemed to be related to the histological types and to the sex of patients. No receptors were found in any of the four studied metastases, including one from breast cancer. The biochemical characterization of the receptors as well as their relevance to tumor biology and to the physiology of the normal tissues where tumors arise, were discussed, and biochemical data were compared with those previously reported.