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Kenneth D. Tew - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Lipophilins as Determinants of Tumor Cell Response to Estramustine
The Journal of pharmacology and experimental therapeutics, 2005Co-Authors: Jody M. Tucker, Zhanna Lipatova, Vladimir Beljanski, Danyelle M. Townsend, Kenneth D. TewAbstract:Estramustine administered orally as Estramustine phosphate (EMP) remains a major tool in hormone refractory prostate cancer chemotherapy. The presence of Estramustine binding protein, prostatin, in prostate tissue may be a determinant of response to treatment. Lipophilins are secretory proteins with homology to prostatin. Reverse transcription-polymerase chain reaction was performed to estimate expression patterns of lipophilins A to C in human biopsies and cell lines resistant to Estramustine. Although lipophilin A was not expressed in prostate tissue, both lipophilins B and C were expressed in normal and tumor prostate without significant differences. For lipophilin C, a somatic mutation (T to C transition at positions 409 and 412) was found in human tumor samples and absent in normal prostate tissue. No consistent response to EMP was observed in enhanced green fluorescent protein (EGFP)-tagged lipophilin C-transfected PC3 cells compared with parental controls. Among these EGFP-lipophilin C clones, no direct correlation between response to EMP treatment (IC50 values) and EGFP expression was observed (p = 0.73). Lipophilin C mRNA levels did not vary significantly between wild-type and Estramustine-resistant cells in prostate (DU145 and PC3) and ovarian (SKOV3) cancer cell lines. Overall, these results suggest that lipophilins are not specific determinants of Estramustine efficacy.
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amplification of the atp binding cassette 2 transporter gene is functionally linked with enhanced efflux of Estramustine in ovarian carcinoma cells
Cancer Research, 1998Co-Authors: Naomi M. Laing, Linda Barone, Martin G Belinsky, Gary D Kruh, Daphne W Bell, Jonathan T Boyd, Joseph R Testa, Kenneth D. TewAbstract:An Estramustine-resistant human ovarian carcinoma cell line, SKEM, was generated to explore resistance mechanisms associated with this agent. Cytogenetic analysis revealed that SKEM cells have a homogeneously staining region (hsr) at chromosome 9q34. Microdissection of the hsr, followed by fluorescence in situ hybridization to SKEM and normal metaphase spreads, confirmed that the amplified region was derived from sequences from 9q34. In situ hybridization with a probe specific for ABC2 , a gene located at 9q34 that encodes an ATP-binding cassette 2 (ABC2) transporter, indicated that this gene is amplified ∼6-fold in the Estramustine-resistant cells. Southern analysis confirmed that ABC2 was amplified in SKEM, and Northern analysis indicated that the ABC2 transcript was overexpressed ∼5-fold. The ABC1 gene located at 9q22–31 was not amplified in the resistant cells, and mRNA levels of several other ABC transporter genes were unaltered. Consistent with the concept that increased ABC2 expression contributes to the resistant phenotype, we observed that the rate of efflux of dansylated Estramustine was increased in SKEM compared with control cells. In addition, antisense treatment directed toward ABC2 mRNA sensitized the resistant cells to Estramustine. Together, these results suggest that amplification and overexpression of ABC2 contributes to Estramustine resistance and provides the first indication of a potential cellular function for this product.
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Interaction of Estramustine with Tubulin Isotypes
Biochemistry, 1997Co-Authors: Naomi M. Laing, Beryl Hartley-asp, Björn Dahllöf, Sulabha Ranganathan, Kenneth D. TewAbstract:The interaction of the antimitotic agent Estramustine with bovine microtubule proteins and purified tubulin was investigated. Direct photoaffinity labeling of microtubule protein with [14C]Estramustine resulted in the labeling of both alpha- and beta-tubulin, and this was inhibited with unlabeled Estramustine in a dose-dependent manner. [14C]Estramustine was incorporated into both the soluble and polymerized forms of tubulin. The affinity constant for Estramustine binding to tubulin was determined by equilibrium dialysis to be 23 +/- 5 mM. Estramustine did not affect [3H]vinblastine binding, and vinblastine had no effect on direct labeling with [14C]Estramustine. Both rhizoxin and paclitaxel decreased the covalent labeling of tubulin with [14C]Estramustine in a dose-dependent fashion and were noncompetitive inhibitors of the binding of Estramustine to tubulin. The binding of colchicine to tubulin was not inhibited by Estramustine as detected by fluorescence and DEAE filter assays. The Estramustine binding site on tubulin is therefore distinct from that of colchicine and vinblastine and may at least partially overlap with the binding site for paclitaxel. In both bovine brain microtubules and cytoskeletal proteins from human prostatic carcinoma cells, the incorporation of [14C]Estramustine into the beta III isotype of tubulin was found to occur with a reduced efficiency compared to that of the other beta-tubulin isotypes and alpha-tubulin. Since this isotype is overexpressed in Estramustine resistant human prostate carcinoma cells, these results indicate that beta III-tubulin may play a role in the response to the effects of Estramustine.
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Comparison of Estramustine with its dihydroxy analogue, estradiol 3-bis(2-hydroxyethyl)carbamate
Structural Chemistry, 1995Co-Authors: David E. Zacharias, Kenneth D. Tew, Jenny P. Glusker, Beryl Hartley-aspAbstract:Estramustine is an antimicrotubule agent that is effective against prostate cancer when used in combination with other microtubule-binding drugs. It is a derivative of estradiol and has a nitrogen mustard group attached via an intervening carbamate group. The molecular dimensions published for Estramustine from crystal structure analyses ( Mol. Pharmacol. 41 ∶569, 1992) indicate that the carbamate group modifies the mustard group by giving considerable double-bond character to the C-N bond. As a result the mustard group cannot form an active aziridine ring and therefore does not show the expected alkylating function. The substitution at O(3) of the aromatic A ring of the steroid moiety has also modified its activity as a steroid. Geometric data are presented here on a compound in which the two chlorine atoms of the mustard group of Estramustine are replaced by hydroxyl groups. The question was, why does the dihydroxy derivative not show biological activity when chlorine atoms do not appear to be activated in Estramustine itself? A comparison of the molecular geometries of the two compounds shows that the dimensions of the carbamate group are similar in both compounds. Therefore it appears that it is the extensive hydrogen-bonding capability of the dihydroxy compound that destroys its Estramustine-like activity. In crystals of both compounds there is a hydrogen bond between O(17) -H and O(19) of another molecule, but the dihydroxy compound can form two more hydrogen bonds. This may possibly prevent it from reaching the site of action of Estramustine or, if it does reach that site, cause it to behave differently.
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Modulation of P-glycoprotein activity by Estramustine is limited by binding to plasma proteins
Cancer, 1995Co-Authors: Charles D. Smith, Gary R. Hudes, Jack T. Zilfou, Xinqun Zhang, Kenneth D. TewAbstract:Background. Estramustine previously has been shown to interact with P-glycoprotein and to restore intracellular accumulation of vinblastine and paclitaxel in cells overexpressing this drug transporter. However, the ability of Estramustine to potentiate the cytotoxicities of several drugs was less than that expected. To resolve this apparent discordance, the authors examined the effects of serum on the actions of Estramustine. Methods. The cytotoxicities of anticancer drugs with or without Estramustine or verapamil toward MCF-7 breast carcinoma cells and a P-glycoprotein-overexpressing subline MCF-7/ADR were determined using the sulforhodamine-binding assay. The extent of intracellular accumulation of [ 3 H]vinblastine and [ 3 H]paclitaxel was determined for each using standard methods, and the binding of radiolabeled drugs to plasma proteins was characterized by equilibrium dialysis. Results. Without serum, the sensitivities of MCF-7/ADR cells to several P-glycoprotein-transported drugs were increased by Estramustine and verapamil. Conversely, when the cells were treated with a 10% serum, the cytotoxicities of these drugs were increased by verapamil, but not by Estramustine. Without serum, intracellular accumulation of [ 3 H]vinblastine and [ 3 H]paclitaxel by MCF-7/ADR cells was increased markedly by verapamil and Estramustine ; however, serum suppressed the effects of Estramustine much more strongly than those of verapamil. Equilibrium dialysis experiments demonstrated that [ 3 H]Estramustine binds to plasma proteins, predominantly albumin, whereas [ 3 H]paclitaxel binds to albumin and alpha 1 -acid-glycoprotein, and [ 3 H]vinblastine binds predominantly to alpha-acid-glycoprotein. Conclusion. Although Estramustine can bind to P-glycoprotein, its effectiveness as a reversing agent in vivo likely is limited by binding to plasma proteins. Cancer 1995 ;75 :2597-2604.
Joseph M. Piepmeier - One of the best experts on this subject based on the ideXlab platform.
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Cancer Research Campaign Suppression of matrix metalloproteinase-2-mediated cell invasion in U87MG, human glioma cells by anti-microtubule agent: in vitro study
2013Co-Authors: D Yoshida, Joseph M. Piepmeier, T Bergenheim, R Henriksson, A TeramotoAbstract:Summary Because microtubules are important components of cell motility and intracellular transport, it is reasonable to propose that the depolymerizing effect of an antimicrotubule agent, Estramustine, on glioma microtubules would modulate cell invasiveness. To determine whether matrix metalloproteinases, key factors in cell invasion, are affected by exposure to Estramustine, a cell proliferation assay, a zymogram, a collagenolysis assay and a haptoinvasion assay were used in this study. The zymogram revealed that an activated (62 kDa) form of matrix metalloproteinase-2 diminished with increasing Estramustine concentrations. The collagenolysis assay demonstrated approximately 2.5- to 21-fold lower rates of enzymatic activity suppressed by Estramustine in a dose-dependent manner at Estramustine concentrations of 1, 5, and 1 0 gM, compared with the control group. On the haptoinvasion assay, no statistically significant difference was seen in the 0.5 gM Estramustine group, whereas 1-10 gM Estramustine groups revealed significant suppression of invasion from 6 to 24 h in a dose-dependent manner. The results suggest that Estramustine suppresses the invasion of U87MG cells in vitro using the decreasing available matrix metalloproteinase-2, an effect caused by the disassembly of microtubules. Suppression of the infiltrative capacity of malignant glioma cells could be of significant value in the treatment of this disease
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Estramustine in malignant glioma
Journal of neuro-oncology, 1996Co-Authors: A. Tommy Bergenheim, Roger Henriksson, Joseph M. Piepmeier, Daizo YoshidaAbstract:Estramustine, a carbamate ester combining 17(3-estradiol and nornitrogen mustard, has primarily been employed in the treatment of advanced prostatic carcinoma. However, a significant amount of preclinical investigation has been directed toward Estramustine's activity against human malignant glioma. These studies have demonstrated that Estramustine has potent antiproliferative effects against malignant glioma both in vitro and in vivo. Similar antimitotic effects also have been demonstrated for other carbamate esters. Estramustine does not impair proliferation of nonneoplastic astrocytes at concentrations that inhibit glioma cells. Although the reasons for this selective activity remain to be determined, it has been shown that malignant gliomas expresses an Estramustine-specific binding site, Estramustine-binding protein, more than brain tissue. In the clinical situation, an uptake and accumulation of Estramustine in human glioma tissue have been demonstrated. Estramustine has been shown to enhance the cytotoxic effects of irradiation in relatively radioresistant glioma cells both in cell culture and in a rat glioma model. Estramustine has been regarded as mainly an anti-mitotic drug but recently other effects such as inhibition of DNA synthesis, induction of apoptosis, and membrane alterations have been shown. This report summarizes the preclinical observations concerning the effects of Estramustine and related compounds on human malignant gliomas. These findings form the basis for proposing further laboratory and clinical investigation regarding Estramustine and human malignant gliomas.
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Targeting microtubule-associated proteins in glioblastoma: a new strategy for selective therapy.
Annals of surgical oncology, 1996Co-Authors: Joseph M. Piepmeier, Daizo Yoshida, Patricia E. Pedersen, Charles A. GreerAbstract:Background: This report presents a summary of preclinical data concerning the use of Estramustine, an antimicrotubule agent against human glioblastoma cells. The strategy for the investigation of Estramustine is predicated on the unique affinity of this agent for microtubule-associated proteins (MAPs).
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Selective Antimitotic Effects of Estramustine Correlate with Its Antimicrotubule Properties on Glioblastoma and Astrocytes
Neurosurgery, 1994Co-Authors: Daizo Yoshida, Ann Cornell-bell, Joseph M. PiepmeierAbstract: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.
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Estramustine Sensitizes Human Glioblastoma Cells to Irradiation
Cancer research, 1994Co-Authors: Daizo Yoshida, Joseph M. Piepmeier, Marc A. WeinsteinAbstract:Abstract 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 estraumstine 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 µm estraumstine had no effect on the percentage of G2-M cells and did not enhance the cytotoxic effects of radiation while 10 µm 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.
Roger Henriksson - One of the best experts on this subject based on the ideXlab platform.
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High-grade astrocytoma treated concomitantly with Estramustine and radiotherapy
Journal of neuro-oncology, 2006Co-Authors: Roger Henriksson, Annika Malmström, Per Bergström, Gertrud Bergh, Thomas Trojanowski, Lars Andreasson, Erik Blomquist, Sonny Jonsborg, Tomas Edekling, Pär SalanderAbstract:Experimental and early clinical investigations have demonstrated encouraging results for Estramustine in the treatment of malignant glioma. The present study is an open randomized clinical trial comparing Estramustine phosphate (Estracyt®) in addition to radiotherapy with radiotherapy alone as first line treatment of astrocytoma grade III and IV. The 140 patients included were in a good clinical condition with a median age of 55 years (range 22–87). Estramustine was given orally, 280 mg twice daily, as soon as the diagnosis was established, during and after the radiotherapy for a period of in total 3 months. Radiotherapy was delivered on weekdays 2 Gy daily up to 56 Gy. Eighteen patients were excluded due to misclassification, leaving 122 patients eligible for evaluation. Overall the treatment was well tolerated. Mild or moderate nausea was the most common side effect of Estramustine. The minimum follow-up time was 5.2 years for the surviving patients. For astrocytoma grade III the median survival time was 10.6 (1.3–92.7) months for the radiotherapy only group and 17.3 (0.4–96.9+) months for the Estramustine + radiotherapy group. In grade IV the corresponding median survival time was 12.3 (2.1–89.2) and 10.3 (0.3–91.7+) months, respectively. Median time to progress for radiotherapy only and radiotherapy and estramustin group in grade III tumours was 6.5 and 10.1 months, respectively. In grade IV tumours the corresponding figures were 5.1 and 3.3 months, respectively. Although there was a tendency for improved survival in grade III, no statistical significant differences were found between the treatment groups. No differences between the two treatment groups were evident with respect to quality of life according to the EORTC QLQ-protocol. In conclusion, this first randomized study did not demonstrate any significant improvement of using Estramustine in addition to conventional radiotherapy, however, a trend for a positive response for the Estramustine group was found in patients with grade III glioma.
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Estramustine-binding Protein in Malignant Glioma in Rat
Journal of Neuro-Oncology, 2000Co-Authors: Anna E. Karlsson, A. Tommy Bergenheim, Per Björk, Jan Sandström, Håkan Hedman, Roger HenrikssonAbstract:Estramustine is a chemotherapeutic drug, used in the treatment of prostatic carcinoma. In the prostate, it binds specifically to a 46 kDa glycoprotein called Estramustine-binding protein (EMBP), which consists of three polypeptide components; C1, C2, and C3, each coded for by a specific gene. Expression of EMBP and binding of Estramustine has also been detected in malignant glioma in both rats and humans. Elevated levels of this protein in astrocytoma have proved to correlate with poor prognosis. In the present work, expression of all three polypeptide components of EMBP was confirmed in an orthotopic rat glioma model with nested reverse transcriptase PCR and Western blot (molecular weights of 8, 10, and 12 kDa). Specific binding of Estramustine with a K _d of 40 for male and 50 for female rats, and a total number of binding sites of 0.7 and 0.4 pmol/mg proteins for male and female rats respectively, was demonstrated with Scatchard plot analysis. These binding characteristics are similar to those of prostatic EMBP. Further studies to elucidate how EMBP expression affects the effect of Estramustine treatment, and its putative prognostic value is of special clinical interest. The confirmation of BMBP expression in BT4C rat glioma demonstrates its suitability as a model system for such studies.
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Estramustine-binding protein in meningioma.
Acta neuropathologica, 1999Co-Authors: Anna E. Karlsson, A. Tommy Bergenheim, Per Björk, Roger HenrikssonAbstract:The presence of Estramustine-binding protein has been suggested to positively correlate with the effect of the cytotoxic drug Estramustine, a combination of estradiol and nornitrogen mustard used in the treatment of prostatic carcinoma. This study demonstrates expression of Estramustine-binding protein in a series of meningioma using different ligand-based and immunological techniques. Scatchard plot analysis showed specific binding sites for [3H]Estramustine in meningioma tissue with a dissociation constant of 22–26 nM. Immunohistochemistry revealed an immunoreactivity in meningioma comparable to that demonstrated in prostatic carcinoma. The mean concentration (n = 6) of Estramustine-binding protein in meningioma, as determined by radioimmunoassay was 159 ng/g tissue (range 18–274 ng/g). Moreover, partial characterization using size exclusion chromatography of [3H]Estramustine-labeled tumor extracts and Western blot analysis of immunoprecipitated samples indicated that the structure of the Estramustine-binding protein in meningioma is similar to that in rat prostate, with three polypeptide components of 10, 14, and 16 kDa, as compared to 8, 10–11, and 12 kDa in rat prostate. In conclusion, the novel observation of Estramustine-binding protein and specific binding of Estramustine in meningioma justify further evaluation regarding the role of Estramustine-binding protein in the growth behavior of meningioma and the potential for Estramustine and similar hormone-related drugs in the treatment of relapsing meningioma.
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Effects of radiotherapy and Estramustine on the microvasculature in malignant glioma
British Journal of Cancer, 1999Co-Authors: M Johansson, A Widmark, Roger HenrikssonAbstract:Tumour angiogenesis is essential for progression of solid tumours and constitutes an interesting target for therapy. However, impaired tumour blood supply may also be an important obstacle for treatment by radiotherapy and chemotherapy. Estramustine has been shown to increase tumour blood flow and potentiate the effect of radiotherapy in experimental glioma. This study investigated the effects of fractionated radiotherapy and Estramustine on angiogenesis in malignant glioma. The intracerebral BT4C rat glioma model was used and the animals were given whole brain radiotherapy 4 Gy × 5 days alone or in combination with Estramustine 20 mg kg-1 i.p. daily. Tumour microvascular density (MVD) was assessed by manual and computerized morphometrical analysis. Expression of vascular endothelial growth factor (VEGF) was studied by in situ hybridization. Radiotherapy decreased MVD to 157 vessels per mm2 compared to 217 vessels per mm2 in controls. Estramustine counteracted this anti-angiogenic effect and potentiated the anti-tumoural effect of radiotherapy. In addition, vessel size increased after Estramustine treatment. Five days after completion of radiotherapy the expression of VEGF was increased in the centre of the tumours. In conclusion, fractionated radiotherapy decreases microvascular density in experimental malignant glioma. This effect was abolished by Estramustine. The anti-vascular effect of irradiation is important to recognize when combining radiotherapy with cytotoxic drugs. © 1999 Cancer Research Campaign
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Pharmacokinetics and Pharmacodynamics of Estramustine Phosphate
Clinical Pharmacokinetics, 1998Co-Authors: A. Tommy Bergenheim, Roger HenrikssonAbstract:Estramustine phosphate (Estramustine phosphate sodium), a carbamate ester combining 17β-estradiol and nor-nitrogen mustard, is a cytotoxic drug used in the treatment of advanced prostatic carcinoma. Because of the radiosensitising effect of this drug there has been a recent increase in interest concerning Estramustine phosphate and its clinical use. It has also been found that the early recommendations of drug administration together with food or milk were inappropriate, since calcium containing food and antacids hamper drug uptake. This may have obscured results from earlier clinical studies with Estramustine phosphate. Estramustine phosphate is currently being re-evaluated for the treatment of other tumours such as glioma and mammary carcinoma. This review summarises the present relatively limited knowledge concerning the pharmacokinetic and pharmacodynamic aspects of Estramustine phosphate and its metabolites.
Daizo Yoshida - One of the best experts on this subject based on the ideXlab platform.
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Estramustine in malignant glioma
Journal of neuro-oncology, 1996Co-Authors: A. Tommy Bergenheim, Roger Henriksson, Joseph M. Piepmeier, Daizo YoshidaAbstract:Estramustine, a carbamate ester combining 17(3-estradiol and nornitrogen mustard, has primarily been employed in the treatment of advanced prostatic carcinoma. However, a significant amount of preclinical investigation has been directed toward Estramustine's activity against human malignant glioma. These studies have demonstrated that Estramustine has potent antiproliferative effects against malignant glioma both in vitro and in vivo. Similar antimitotic effects also have been demonstrated for other carbamate esters. Estramustine does not impair proliferation of nonneoplastic astrocytes at concentrations that inhibit glioma cells. Although the reasons for this selective activity remain to be determined, it has been shown that malignant gliomas expresses an Estramustine-specific binding site, Estramustine-binding protein, more than brain tissue. In the clinical situation, an uptake and accumulation of Estramustine in human glioma tissue have been demonstrated. Estramustine has been shown to enhance the cytotoxic effects of irradiation in relatively radioresistant glioma cells both in cell culture and in a rat glioma model. Estramustine has been regarded as mainly an anti-mitotic drug but recently other effects such as inhibition of DNA synthesis, induction of apoptosis, and membrane alterations have been shown. This report summarizes the preclinical observations concerning the effects of Estramustine and related compounds on human malignant gliomas. These findings form the basis for proposing further laboratory and clinical investigation regarding Estramustine and human malignant gliomas.
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Targeting microtubule-associated proteins in glioblastoma: a new strategy for selective therapy.
Annals of surgical oncology, 1996Co-Authors: Joseph M. Piepmeier, Daizo Yoshida, Patricia E. Pedersen, Charles A. GreerAbstract:Background: This report presents a summary of preclinical data concerning the use of Estramustine, an antimicrotubule agent against human glioblastoma cells. The strategy for the investigation of Estramustine is predicated on the unique affinity of this agent for microtubule-associated proteins (MAPs).
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Selective Antimitotic Effects of Estramustine Correlate with Its Antimicrotubule Properties on Glioblastoma and Astrocytes
Neurosurgery, 1994Co-Authors: Daizo Yoshida, Ann Cornell-bell, Joseph M. PiepmeierAbstract: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.
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Estramustine Sensitizes Human Glioblastoma Cells to Irradiation
Cancer research, 1994Co-Authors: Daizo Yoshida, Joseph M. Piepmeier, Marc A. WeinsteinAbstract:Abstract 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 estraumstine 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 µm estraumstine had no effect on the percentage of G2-M cells and did not enhance the cytotoxic effects of radiation while 10 µm 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.
Sten Nilsson - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and In Vitro Evaluation of [carbonyl-11C]Estramustine and [carbonyl-11C]Estramustine Phosphate
Steroids, 1998Co-Authors: Pelle Lidström, Sten Nilsson, Thomas A. Bonasera, Marcela Marquez-m, Mats Bergström, Bengt LångströmAbstract:[carbonyl-11C]Estramustine and [carbonyl-11C]Estramustine phosphate were synthesized from [11C]phosgene using a one pot procedure. [carbonyl-11C]Estramustine was obtained in 31-43% decay corrected yield based on radioactivity trapped in the reaction vessel. The product was obtained 25 min after the end of radionuclide production with a specific radioactivity of 0.38-1.11 Ci/mumol. A method was developed yielding [carbonyl-11C]Estramustine phosphate in 29-45% decay corrected yield based on trapped radioactivity, without purification of the [carbonyl-11C]Estramustine intermediate. The product was obtained within 40 min of the end of radionuclide production with a specific radioactivity of 0.59-0.86 Ci/mumol. Results from in vitro experiments suggest that because of their high nonspecific binding, the compounds are unsuitable for positron emission tomography as imaging agents for the Estramustine binding protein in cancer.
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Estramustine binding protein embp in renal cell carcinoma immunohistochemistry immunoscintigraphy and in vitro Estramustine effects
Acta Oncologica, 1996Co-Authors: Maliha Edgren, Henry Letocha, Karl Mikael Kälkner, Hans Nordgren, Jan-erik Westlin, Sten NilssonAbstract:The present report shows that the human renal cell carcinoma (RCC) cell lines, A498 and CAKI-2, express the Estramustine-binding protein (EMBP). The RCC cell lines investigated were highly sensitive for Estramustine, with cell arrest in atypical metaphase. In vitro experiments using a fluorimetric cytotoxicity assay (FMCA) showed a pronounced cytotoxic effect mediated by Estramustine. Immunohistochemical analysis of tumour specimens from patients with RCC showed positive staining for EMBP in 12/16 cases. Immunoscintigraphy was performed in an experimental system in nude mice, heterotransplanted with the CAKI-2 cell line. A radiolabelled monoclonal anti-EMBP antibody was used. The results show a specific uptake of the antibody in the RCC tumour, expressed as a percentage of the injected dose per gram tissue, which ranged from 4.03 to 6.9. The results obtained form the basis for clinical studies on the feasibility of utilizing Estramustine in the management of RCC. Immunoscintigraphy using the monoclonal an...
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Estramustine-binding protein (EMBP) content in four different cell lines and its correlation to Estramustine induced metaphase arrest.
Anticancer research, 1996Co-Authors: Solveig Eklöv, Per Björk, Ensaf A. Mahdy, Kenneth Wester, Per-uno Malmström, Christer Busch, Sten NilssonAbstract:Estramustine-binding protein content in four different cell lines and its correlation to Estramustine induced metaphase arrest.
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Estramustine-Binding Protein (EMBP) in Renal Cell Carcinoma Immunohistochemistry, Immunoscintigraphy and in Vitro Estramustine Effects
Acta oncologica (Stockholm Sweden), 1996Co-Authors: Maliha Edgren, Henry Letocha, Karl Mikael Kälkner, Hans Nordgren, Jan-erik Westlin, Sten NilssonAbstract:The present report shows that the human renal cell carcinoma (RCC) cell lines, A498 and CAKI-2, express the Estramustine-binding protein (EMBP). The RCC cell lines investigated were highly sensitive for Estramustine, with cell arrest in atypical metaphase. In vitro experiments using a fluorimetric cytotoxicity assay (FMCA) showed a pronounced cytotoxic effect mediated by Estramustine. Immunohistochemical analysis of tumour specimens from patients with RCC showed positive staining for EMBP in 12/16 cases. Immunoscintigraphy was performed in an experimental system in nude mice, heterotransplanted with the CAKI-2 cell line. A radiolabelled monoclonal anti-EMBP antibody was used. The results show a specific uptake of the antibody in the RCC tumour, expressed as a percentage of the injected dose per gram tissue, which ranged from 4.03 to 6.9. The results obtained form the basis for clinical studies on the feasibility of utilizing Estramustine in the management of RCC. Immunoscintigraphy using the monoclonal anti-EMBP antibody is of potential use for in vivo characterization of the malignancy and in the selection patients suitable for treatment with Estramustine.
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Estramustine potentiates the radiation effect in human prostate tumor transplant in nude mice
The Prostate, 1994Co-Authors: Solveig Eklöv, Jan-erik Westlin, Göran Rikner, Sten NilssonAbstract:In this study, we have investigated the combined effect of Estramustine treatment and external beam radiation on human prostatic cancer tumor cells (DU 145) transplanted in nude mice. The treatment was given according to two different schedules. In the first treatment regimen, Estramustine was administered intraperitoneally (i.p.) intermittently for 20 days. The radiation therapy, which was started on day 9, was given with 6 Gy fractions during an 11-day-long period to a total dose of 36 Gy. The combination treatment (Estramustine + radiation) resulted in a significant tumor growth retardation as compared to the control group. This pronounced effect was seen neither with radiation alone nor with Estramustine alone. In order to further extend the radiation treatment time, a second therapy regimen was employed. In this part of the study, Estramustine was administrated i.p. intermittently for 26 days. The radiation therapy, which was started on day 6, was given with 4 Gy fractions during a 21-day-long period to a total dose of 40 Gy. Under these conditions, a significant tumor growth retardation was disclosed, when comparing the combination treatment (Estramustine + radiation) with radiation alone. The tumors were analyzed for content of necrosis and proliferative activity. The largest proportion of necrosis was seen in the combination (Estramustine + radiation) treatment group. Also, the tumors from this group expressed a decreased proliferative activity. The data indicate that Estramustine acts as a radiosensitizing agent in human prostatic cancer cells in vivo. The radiosensitizing properties of the drug encourage further studies with respect to clinical application. © 1994 Wiley-Liss, Inc.