Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0017636 (glioblastoma)
 18,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Estramustine is an estradiol-based agent that accumulates in cells containing estramustine binding protein. Previous studies have shown that this binding site is expressed in human glioblastoma cells and that estramustine accumulates in glioma cells, resulting in a concentration-dependent inhibition of proliferation. We have shown that estramustine treatment results in a rapid inhibition of deoxyribonucleic acid synthesis (within 4 h) in human glioblastoma cells associated with an alteration of cell size and shape, consistent with its known antimicrotubule activity. To extend these findings, we performed an immunohistochemical analysis of microtubules with a monoclonal antibody to beta-tubulin, using a colorimetric assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide to measure the antimitotic effects of estramustine on both human glioblastoma and astrocyte cultures. Within 4 hours, estramustine (10 mumol/L) caused a dramatic alteration in the tubulin staining in glioma cells, characterized by a disorganization in microtubules. Cell shape and microtubule staining in astrocytes were relatively preserved. Estramustine had a concentration-dependent cytotoxic effect in tumor cultures, whereas it had no effect on astrocyte viability at any concentration. Differences in the antimitotic effects do not appear to be related to variations in proliferation rates among these different types of cells. These data suggest that although estramustine is a potent inhibitor of proliferation in glioblastoma cells, it has modest antiproliferative effects on astrocytes and its selective activity is closely correlated with its antimicrotubule properties.
 ...
PMID:Selective antimitotic effects of estramustine correlate with its antimicrotubule properties on glioblastoma and astrocytes. 805 84

Estramustine is an estradiol-based antimicrotubule agent that accumulates in malignant glioma cells, resulting in a concentration-dependent inhibition of proliferation. This agent has been shown to synchronize human glioma cells at G2-M consistent with its known effects on the mitotic spindle and potentially could be used as a radiation enhancer. We determined the effects of estramustine on the cell cycle of glioblastoma cells by flow cytometry. These findings were compared with clonogenic survival in cells pretreated with varying concentrations of estramustine prior to irradiation. These experiments indicated that 24 h treatment with 1 microM estramustine had no effect on the percentage of G2-M cells and did not enhance the cytotoxic effects of radiation while 10 microM estramustine increased the G2-M fraction by 100% associated with a potentiation factor as high as 8.5 and a relative radiation sensitivity at 70% cytotoxicity of 5.2 compared with 15.4 for control cells. Estramustine can be administered p.o. on a daily schedule with minimal systemic toxicity. These data suggest that estramustine may be an effective radiation enhancer for glioblastoma.
 ...
PMID:Estramustine sensitizes human glioblastoma cells to irradiation. 813 40

Estramustine is an estradiol-based agent that has been shown to accumulate in human glioma cells, resulting in a concentration-dependent alteration in cell size and shape within minutes and an inhibition of proliferation over 3 to 6 days. We evaluated human glioblastoma cultures with [3H]thymidine incorporation assays to determine estramustine's early effects on deoxyribonucleic acid synthesis in these tumors. Because estramustine shares a common structural motif with other antimicrotubule drugs, we synthesized four A-ring conjugates of estrone that contained a carbamate moiety but lacked nitrogen mustard. These analogs were examined by [3H]thymidine incorporation and compared with vinblastine. Greater than 70% inhibition of [3H]thymidine incorporation occurred within 1 hour of treatment with estramustine at 10(-5) mol/L, which increased to 80% inhibition at 4 hours. Ethyl carbamate JE208 was nearly as effective as estramustine in inhibiting deoxyribonucleic acid synthesis, and both were more effective than vinblastine. The inhibitory effects of estramustine and estrone analogs were reversible; vinblastine was not reversible. Although estramustine and JE208 induced similar antiproliferative and morphological changes in glioblastoma cells that persisted for at least 4 days, there was a modest recovery of morphology and thymidine incorporation with JE208 after prolonged treatment. The common findings with estramustine and JE208 suggest that these agents may have a similar mechanism of action and form the basis for the investigation of new agents that may rapidly and reversibly inhibit glioblastoma.
 ...
PMID:Estramustine and estrone analogs rapidly and reversibly inhibit deoxyribonucleic acid synthesis and alter morphology in cultured human glioblastoma cells. 838 27

Patients with high grade glioma generally have poor prognoses. Addition of radiosensitizing agents might improve the response to irradiation. The chemotherapeutic agent estramustine sensitizes experimental gliomas to radiation. Gliomas express estramustine binding proteins, and cytotoxic concentrations of estramustine metabolites are found in gliomas after oral administration. Twenty three patients, aged 25-78, with new or recurrent high grade glioma were treated with estramustine and radiosurgery and/or radiotherapy. Patients with recurrent tumors were treated with estramustine and Gamma Knife stereotactic radiosurgery; eligible tumors were limited to 4 cm maximal diameter. Patients with newly diagnosed tumors were treated with estramustine and fractionated radiotherapy, with radiosurgery also performed if the tumor was less than 4 cm maximal diameter. Estramustine (16 mg/kg per day orally) was started three days prior to radiosurgery, or, if only radiotherapy was performed, on the first day of radiotherapy. Estramustine was continued until the completion of radiosurgery and/or radiotherapy (72 Gy, 60 fractions, 1.2 Gy bid over 6 weeks). Of the 13 patients treated for newly diagnosed glioblastoma, median survival was 16 months with 38% 2-year survival. Of five patients treated for recurrent glioblastoma, survival was 3, 8, 9, 15, and 23 + months. Two patients with recurrent anaplastic astrocytoma survived for 24 and 48+ months. One patient with recurrent anaplastic mixed glioma survived 5+ months. Two patients with newly diagnosed anaplastic oligodendroglioma survived 20 and 42+ months. Four of the new glioblastoma patients developed deep vein thrombosis. The results of this pilot study indicate some benefit, and further investigation incorporating estramustine into clinical trials is suggested.
 ...
PMID:Pilot study of estramustine added to radiosurgery and radiotherapy for treatment of high grade glioma. 1507 70