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PubMed2001

Preclinical mechanisms of action of docetaxel and docetaxel combinations in prostate cancer.

Docetaxel, a semisynthetic taxane, has exhibited significant single-agent activity against prostatic tumors. In phase I/II studies, single-agent docetaxel and the combination of docetaxel plus estramustine were effective in inducing prostate-specific antigen reductions of > or =50% in men with androgen-independent prostate cancer (AIPC). The underlying reason for docetaxel's clinical activity against prostate cancer has been a focus of ongoing research. Docetaxel is believed to have a twofold mechanism of antineoplastic activity: (1) inhibition of microtubular depolymerization, and (2) attenuation of the effects of bcl-2 and bcl-xL gene expression. Taxane-induced microtubule stabilization arrests cells in the G(2)M phase of the cell cycle and induces bcl-2 phosphorylation, thereby promoting a cascade of events that ultimately leads to apoptotic cell death. In preclinical studies, docetaxel had a higher affinity for tubulin and was shown to be a more potent inducer of bcl-2 phosphorylation than paclitaxel. Laboratory evidence also supports the clinical evaluation of docetaxel-based combinations that include agents such as trastuzumab and/or estramustine. The pathways for docetaxel-induced apoptosis appear to differ in androgen-dependent and androgen-independent prostate cancer cells. Further elucidation of these differences will be instrumental in designing targeted regimens for the treatment of localized and advanced prostate cancer.

Antineoplastic Agents, Phytogenic↗
PubMed2000

A model of superficial bladder cancer using fluorescent tumour cells in an organ-culture system.

OBJECTIVE: To develop a reproducible in vitro simulation of superficial bladder cancer for testing cytotoxic agents at clinically relevant concentrations. MATERIALS AND METHODS: Square explants (5 mm) of rat bladder were cultured in Petri dishes in minimal volumes of Waymouth's MB 752/1 medium supplemented with 10% fetal calf serum, antibiotics and glutamine. Parental and resistant MGH-U1 urothelial cancer cells were transfected with a green fluorescent protein (GFP) vector. Transfectants were purified by flow cytometry. Cells were seeded onto the prepared organ cultures and images obtained using confocal microscopy. The tumour colonies were confirmed using scanning electron microscopy. Conventional intravesical cytotoxic agents including epirubicin, mitomycin-C and estramustine were tested in the system. RESULTS: Colonies of GFP-MGH-U1 cells became established on the explants and were identified by confocal microscopy; the development of the colonies was then followed over several days. Staining the explant for viability allowed imaging of normal urothelium on the explant surface or surrounding skirt of urothelial cells. The conventional cytotoxic agents epirubicin, mitomycin C and estramustine showed the expected differential responses to parental and resistant cell types. The colonies were able to survive high concentrations of the drug, equivalent to those in clinical use. The colonies were imaged serially over a period of several days. CONCLUSION: This system provides a more realistic model for testing cytotoxic agents for use in intravesical therapy, by allowing clinically relevant concentrations of drugs to be tested. The differential properties of the parental and resistant cells are maintained. The model also enables the same tumour colony to be imaged over several days in culture. The model may also be adapted for use in testing the effects of drugs on normal urothelium and the study of the effects of growth factors.

Animals↗
PubMed1995

Prostate cancer in the era of prostate-specific antigen.

The number of cases of prostate cancer diagnosed increased by 15% in the past year. This trend is likely to continue as prostate-specific antigen testing was approved for screening during the past year. The result is that mroe patients are being diagnosed at an earlier and presumably curable stage, although the long-term impact on survival has not been proven. Two large national randomized comparisons were initiated to assess the value of early detection (Prostate, Lung, Colorectal, and Ovarian cancer screening trial) and of early treatment (Prostate Cancer Intervention Versus Observation Trial). Evolving data from early detection studies suggest that the majority of cancers diagnosed are clinically significant. Further, criteria for "deferred treatment" approaches are likewise beginning to evolve. The more widespread use of nomograms based on digital rectal examination findings, Gleason grade, and baseline prostate-specific antigen has led to more refined treatment selection. Patients deemed incurable by local means are being referred for combined modality approaches. For more advanced disease, several new hormonal approaches are evolving, and for those with relapsing tumors, responses to antiandrogen withdrawal were extended to Casodex, (Zeneca Pharmaceuticals, Macclesfield, UK) and a number of nonhormonal treatments such as combinations of estramustine and etoposide estramustine and vinblastine, and doxorubicin and ketoconazole are showing clinical benefit.

Humans↗
PubMed1998

Incidence and characteristics of antiandrogen withdrawal syndrome in prostate cancer after treatment with chlormadinone acetate.

OBJECTIVES: In patients with progressive prostate cancer who have been treated with surgical or medical castration plus an antiandrogen, antiandrogen withdrawal can result in a significant decline in serum prostate-specific antigen (PSA). Although the incidence of antiandrogen withdrawal syndrome after combination treatment with the nonsteroidal antiandrogen flutamide has been thoroughly documented, the phenomenon clearly occurs in many other combination therapies and is presently being widely investigated. This paper would like to contribute to this effort by describing the endocrine withdrawal phenomenon in patients treated with combinations of castration plus chlormadinone acetate, ethynylestradiol or estramustine phosphate. MATERIALS AND METHODS: Clinical records of 68 prostate cancer patients who had been treated with surgical castration plus the administration of chlormadinone acetate, ethynylestradiol or estramustine phosphate, and who had shown clinical progression associated with a steady increase in serum PSA, were investigated. Forty-one cases were evaluable for changes in PSA after discontinuation of the hormonal agents. RESULTS: Of 28 patients who had been treated with chlormadinone acetate, 12 (42.9%) revealed 50% or more decline in PSA level following withdrawal of the agent. Among these, 5 cases (17.9%) showed subjective and/or objective improvements. There was no significant difference in histological grade of the tumor at diagnosis, mode of progression, time interval from the start of endocrine therapy to discontinuation of the hormonal agents, or PSA level at withdrawal of the agents between patients who did develop antiandrogen withdrawal syndrome and those who did not. CONCLUSION: When a steady increase in serum PSA is noted in a prostate cancer patient who has been treated with castration plus a steroidal antiandrogen, discontinuation of the antiandrogen may benefit the patient.

Aged↗
PubMed2006

Non-hormonal systemic therapy in men with hormone-refractory prostate cancer and metastases: a systematic review from the Cancer Care Ontario Program in Evidence-based Care's Genitourinary Cancer Disease Site Group.

BACKGROUND: Prostate cancer that has recurred after local therapy or disseminated distantly is usually treated with androgen deprivation therapy; however, most men will eventually experience disease progression within 12 to 20 months. New data emerging from randomized controlled trials (RCTs) of chemotherapy provided the impetus for a systematic review addressing the following question: which non-hormonal systemic therapies are most beneficial for the treatment of men with hormone-refractory prostate cancer (HRPC) and clinical evidence of metastases? METHODS: A systematic review was performed to identify RCTs or meta-analyses examining first-line non-hormonal systemic (cytotoxic and non-cytotoxic) therapy in patients with HRPC and metastases that reported at least one of the following endpoints: overall survival, disease control, palliative response, quality of life, and toxicity. Excluded were RCTs of second-line hormonal therapies, bisphosphonates or radiopharmaceuticals, or randomized fewer than 50 patients per trial arm. MEDLINE, EMBASE, the Cochrane Library, and the conference proceedings of the American Society of Clinical Oncology were searched for relevant trials. Citations were screened for eligibility by four reviewers and discrepancies were handled by consensus. RESULTS: Of the 80 RCTs identified, 27 met the eligibility criteria. Two recent, large trials reported improved overall survival with docetaxel-based chemotherapy compared to mitoxantrone-prednisone. Improved progression-free survival and rates of palliative and objective response were also observed. Compared with mitoxantrone, docetaxel treatment was associated with more frequent mild toxicities, similar rates of serious toxicities, and better quality of life. More frequent serious toxicities were observed when docetaxel was combined with estramustine. Three trials reported improved time-to-disease progression, palliative response, and/or quality of life with mitoxatrone plus corticosteroid compared with corticosteroid alone. Single trials reported improved disease control with estramustine-vinblastine, vinorelbine-hydrocortisone, and suramin-hydrocortisone compared to controls. Trials of non-cytotoxic agents have reported equivocal results. CONCLUSION: Docetaxel-based chemotherapy modestly improves survival and provides palliation for men with HRPC and metastases. Other than androgen deprivation therapy, this is the only other therapy to have demonstrated improved overall survival in prostate cancer in RCTs. Further investigations to identify more effective therapies for HRPC including the use of systemic therapies earlier in the natural history of prostate cancer are warranted.

Antineoplastic Agents↗
PubMed2003

Docetaxel (taxotere) in the treatment of prostate cancer.

Docetaxel (Taxotere) is a taxoid derived from the needles of the European yew tree, Taxus baccata. With an overall prostate-specific antigen response rate of 42% in four Phase II studies, docetaxel has important single-agent activity in androgen-independent prostate cancer. Phase II studies suggest that the addition of estramustine (Emcyt) to docetaxel results in higher response rates but also increased toxicity. Docetaxel with and without estramustine is being evaluated in Phase III studies that will provide definitive information about its role in androgen-independent prostate cancer. Novel combinations of docetaxel with biologic response modifiers are in early stages of development. Similarly, a number of investigators are conducting exploratory trials that incorporate docetaxel into multimodality approaches to high-risk localized prostate cancer treatment.

Animals↗
PubMed1989

Flutamide. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in advanced prostatic cancer.

Flutamide is a non-steroidal antiandrogenic drug devoid of hormonal agonist activity. Flutamide appears to be a specific antiandrogen only at androgen-dependent accessory genital organs. Its pharmacological activity is due substantially to the principal metabolite, 2-hydroxyflutamide. In comparative trials involving small numbers of patients with previously untreated advanced prostatic cancer, flutamide 750mg daily is comparable with stilboestrol 1 or 3mg daily and with estramustine 560 or 840mg daily. Treatment of newly diagnosed advanced prostatic cancer with flutamide plus a luteinising hormone releasing hormone (LHRH) agonist has produced very promising results, and appears to prolong survival relative to that achieved with leuprolide alone. However, these results require confirmation in suitably designed prospective studies. In previously treated patients refractory to castration, flutamide 750mg daily appears comparable in efficacy to estramustine phosphate 600 mg/m2 daily. Apart from a high incidence (34 to 100%) of gynaecomastia flutamide monotherapy is usually well tolerated, and has the advantage of preserving libido and sexual potency in at least 80% of patients. Gynaecomastia is infrequent, however, when flutamide is used in conjunction with surgical castration or an LHRH agonist. Thus, flutamide is a suitable alternative to other systemic treatment in patients with advanced prostatic cancer who wish to preserve sexual potency. In combination with an LHRH agonist flutamide may become a first-line agent for previously untreated patients with cancer of the prostate.

Anilides↗
PubMed2005

An evaluation of high-doses ketoconazole with hydrocortisone substitution in hormone-refractory prostate cancer.

We investigated the efficacy of ketoconazole, an inhibitor of testicular and adrenal biosynthesis, for treating patients with progression of hormone-refractory prostate cancer. The study comprised 35 patients with progressive disease despite salvage treatment with estramustine with or without vinblastine. Treatment consisted high-doses ketoconazole (400 mg three times daily) and hydrocortisone substitution. Patients were monitored clinically and with serial PSA measurements every 3 months. The principal endpoint of the study was PSA response to applied therapy. Of the 35 patients, 18 (51.4%) showed a decrease in PSA 50% with a median duration of 30 weeks (range 6-60 weeks). A PSA reduction 50% was seen in 15 of 31 patients (48.4%) with established metastasis. Twelve patients (34.2%), all of whom had metastasis, exhibited a PSA decrease 80% with median duration of 9 months (range 3-48 months). The median time to progression was 6.3 months (range 0-27 months) and the median survival time was 12.5 months (range 3-48 months). Twelve (34.3%) reported toxicity related to ketoconazole, whereas no patients required discontinuation of therapy. It is apparent from this study that a reasonable percentage of patients failing salvage chemotherapy (estramustine with or without vinblastine) respond favorably to high-dose ketoconazole and that toxicity is mild. In the absence of studies demonstrating better survival with chemotherapy, we believe that a trail of ketoconazole should be considered when progression of PSA occurs, following initial hormonal androgen deprivation.

Aged↗
PubMed2007

A systematic review and economic model of the clinical effectiveness and cost-effectiveness of docetaxel in combination with prednisone or prednisolone for the treatment of hormone-refractory metastatic prostate cancer.

OBJECTIVES: A systematic review was undertaken and an economic model constructed to evaluate the clinical effectiveness and cost-effectiveness of docetaxel (Taxotere, Sanofi-Aventis) in combination with prednisone/prednisolone for the treatment of metastatic hormone-refractory prostate cancer (mHRPC). The main comparators considered were other established chemotherapy regimens and best supportive care. DATA SOURCES: Twenty-one resources (including MEDLINE, EMBASE and the Cochrane Library) were searched to April 2005. REVIEW METHODS: Two reviewers independently assessed studies for inclusion. Data from included studies were extracted and quality assessed. Where appropriate, outcomes were synthesised using formal analytic approaches. A new economic model was developed in order to establish the cost-effectiveness of docetaxel compared with a range of potential comparators. A separate review was undertaken to identify sources of utility data required to estimate quality-adjusted life-years (QALYs). Sensitivity analyses were also undertaken to explore the robustness of the main analysis to alternative assumptions related to quality of life. Monte Carlo simulation was used to propagate uncertainty in input parameters through the model in such a way that the results of the analysis could be presented with their uncertainty. The impact of uncertainty surrounding the decision was established using value of information and implementation approaches. RESULTS: Seven randomised controlled trials were identified that met the inclusion criteria. A direct comparison of docetaxel plus prednisone versus mitoxantrone plus prednisone in an open-label randomised trial showed improved outcomes for docetaxel plus prednisone in terms of overall survival, quality of life, pain and prostate-specific antigen decline. Two other chemotherapy regimens that included docetaxel: docetaxel plus estramustine and docetaxel plus prednisone plus estramustine, also showed improved outcomes in comparison with mitoxantrone plus prednisone. Indirect comparison suggested that docetaxel plus prednisone seems to be superior to corticosteroids alone in terms of overall survival. Conclusions on cost-effectiveness were primarily informed by the results of the in-house model. This indicated that mitoxantrone plus a corticosteroid is probably cheaper and more effective than corticosteroid alone. Compared with mitoxantrone plus prednisone/prednisolone, the use of docetaxel plus prednisone/prednisolone (3-weekly) appears cost-effective only if the NHS is prepared to pay 33,000 pounds per QALY. The incremental cost-effectiveness ratio associated with docetaxel plus prednisone (3-weekly) remained fairly robust to these variations with estimates ranging from 28,000 pounds to 33,000 pounds per QALY. Value of information analysis revealed that further research is potentially valuable. Given a maximum acceptable ratio of 30,000 pounds per QALY, the expected value of information was estimated to be approximately 13 million pounds. CONCLUSIONS: This systematic review of the research suggests that docetaxel plus prednisone seems to be the most effective treatment for men with mHRPC. The economic model suggests that treatment with docetaxel plus prednisone/prednisolone is cost-effective in patients with mHRPC provided the NHS is prepared to pay 33,000 pounds per additional QALY. Future research should include the direct assessment of quality of life and utility gain associated with different treatments, including the effect of adverse events of treatment, using generic instruments, which are suitable for the purposes of cost-effectiveness analyses.

Antineoplastic Agents↗
PubMed2000

The role of chemotherapy in prostate cancer. Minireview.

Hormonal therapy in disseminated prostate cancer is effective in 70-80% of patients and prolongs their lives of a mean 1-2 years. Sooner or later, androgen independence develops due to a multifactorial mechanism. A smaller part of patients may respond to second-line hormonal manipulations (antiandrogen withdrawal, adrenal enzymes synthesis inhibitors, corticosteroids). In hormone-refractory disease only about 30% of patients would respond to chemotherapy. In the standard chemotherapy the mostly used cytotoxic agents are anthracyclines, platinum derivatives, vinca alkaloids and cyclophosphamide. However, combined chemotherapy is not more effective than monotherapy. Conventional chemotherapy may improve especially the quality of life. The median survival in chemotherapy patients (6-12 months) is not significantly longer when compared with the best supportive care. In recent years the main concern has been focused on new cytotoxic drugs and different combinations with hormonal agents. In Phase II studies the combinations of estramustine with oral etoposide, estramustine with taxanes and alternating weekly regimens (doxorubicin, ketoconazole/estramustine, vinblastine) show higher response rates (53-69% of patients with prostate-specific antigen decline of more than 50%) and longer survival (13-19 months) than conventional chemotherapy.

Antineoplastic Agents, Hormonal↗
PubMed2005

Recent docetaxel studies establish a new standard of care in hormone refractory prostate cancer.

INTRODUCTION: Treatment of hormone refractory prostate cancer (HRPC) has generally aimed at increasing symptom free survival in asymptomatic patients and improving quality of life in symptomatic patients. However, recent randomized studies might be shifting the paradigm towards achieving an improved overall survival. METHODS: Two large randomized controlled studies were conducted using mitoxantrone plus prednisone as a control arm compared to docetaxel-based regimens. RESULTS: In the TAX 327 trial, 3-weekly docetaxel plus prednisone proved significantly superior to mitoxantrone plus prednisone (an established reference regimen) in extending survival, reducing levels of prostate specific antigen (PSA), controlling pain and improving quality of life. The Southwest Oncology Group's study (protocol 99-16) randomized patients to either docetaxel plus estramustine or mitoxantrone plus prednisone. Compared with the mitoxantrone regimen, docetaxel plus estramustine significantly extended median overall survival and time to progression. Men treated with the docetaxel regimen were also more likely to have a PSA response. In this study, the two regimens were similarly effective in relieving pain. CONCLUSION: These studies have an important impact on the management strategy of hormone refractory prostate cancer. Docetaxel is the first agent shown significantly to extend survival in HRPC. Although this proven benefit must be balanced against toxicity, docetaxel should now be considered the standard of care for most patients that fail first-line or more hormonal manipulations. Drug combinations which may further extend survival and improve quality of life are actively being pursued, as is the possibility of using docetaxel in the adjuvant setting.

Aged↗
PubMed2005

[Prostate cancer: update].

The study of mitotic transduction of the signal showed that overexpression of pAkt and reduction in pERK expression would be associated a biological relapse. For tumors T1-3 N0M0 at the high risk of local relapse after prostatectomy, an immediate radiotherapy compared with a differed radiotherapy (at the time of PSA relapse), showed a significant reduction in the rate of local relapse and an ameliorated progression free survival. The effectiveness of the docetaxel was confirmed in two phase III randomized clinical trials : TAX-327 with 3 arms compared docetaxel every 21 days, docetaxel every 7 days and mitoxantrone. All arms were prednisone-based. An increase in overall survival, PSA progression free survival, PSA response rate and a pain reduction were highlighted in the docetaxel arm every 21 days. Docetaxel obtained at the end of this study the marketing authorization in this indication and became the treatment of reference. The SWOG 99-16 study compared the docetaxel estramustine association with the same arm of reference, mitoxantrone and prednisone, with similar results. The addition of estramustine to the docetaxel seems to improve the PSA response rate and progression free survival, but with a greater embolic toxicity. The addition of an antiangiogenic agent, the thalidomide, to docetaxel, improves progression free survival and overall survival. PSA responses were observed with an inhibitor of the proteasome, the bortezomib, in monotherapy, contrary to the imatinib which in monotherapy didn't have any effectiveness. Studies in association with docetaxel are ongoing. Some biological responses were observed with a vaccine anti MUC-1 and must be confirmed on a greater series of patients. The docetaxel impact on localized disease is actually evaluated.

Androgen Antagonists↗
PubMed1986

Carcinogen-binding proteins in the rat ventral prostate: specific and nonspecific high-affinity binding sites for benzo(a)pyrene, 3-methylcholanthrene, and 2,3,7,8-tetrachlorodibenzo-p-dioxin.

The polychlorinated dibenzodioxin [3H]-2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) and the carcinogens [3H]benzo(a)pyrene and [3H]-3-methylcholanthrene bound to saturable binding sites in cytosol from the rat ventral prostate. Analysis of equilibrium binding parameters in diluted cytosol preparations indicated an apparent Kd of approximately 2 nM and a binding capacity of approximately 1 nmol/mg cytosolic protein, corresponding to approximately 5% of the total protein content. However, gel permeation chromatography analysis as well as velocity sedimentation analysis on sucrose gradients of [3H]TCDD-labeled rat prostatic cytosol indicated binding of [3H]TCDD to two discrete species. These analyses indicated a sedimentation coefficient of 3.6-3.8S, a Stokes radius of 25-28 A, and a calculated relative molecular weight of 42,000-45,000 for the most abundant binding species. The other binding species sedimented at 4-5S under high ionic strength conditions and at 8-10S under low ionic strength conditions and had a Stokes radius of approximately 60 A, a relative molecular weight of approximately 100,000 and an estimated concentration of 5-20 fmol/mg cytosolic protein. Binding of [3H]TCDD to this species was displaceable by a 200-fold M excess of 2,3,7,8-tetrachlorodibenzofuran. Therefore, this species was tentatively identified as the TCDD receptor. The properties of the high-capacity binder of [3H]TCDD were found to be similar to the characteristics of a protein previously purified from the rat ventral prostate, prostatic secretory protein, which binds androgens as well as estramustine, a nitrogen mustard derivative of estradiol. The binding of estramustine to diluted prostatic cytosol was shown to be competitively inhibited by 2,3,7,8-tetrachlorodibenzofuran. Moreover, purified prostatic secretory protein bound [3H]TCDD, [3H]benzo(a)pyrene, as well as [3H]-3-methylcholanthrene. It is suggested that binding to this protein is responsible for the high-binding capacity of carcinogens in cytosol from the rat ventral prostate.

Animals↗
PubMed1981

[Current aspects of hormonal therapy in prostate cancer].

The following endocrine treatment modalities have been used in advanced prostatic carcinoma: 1. orchiectomy plus estrogens; 2. primary orchiectomy with delayed estrogen employment; 3. initial estrogen therapy with delayed orchiectomy; 4. initial cyproterone acetate or medroxyprogesterone acetate; 5. a combination treatment: estramustine phosphate, cyproterone acetate or estrogens plus bromocriptine. The application of phase-III studies permits the subsequent conclusions: Simultaneous orchiectomy is to no advantage (exception: urinary stasis). Cyproterone acetate does neither yield better nor worse results regarding survival than estrogen alone, but has fewer side effects. Estrogens and cyproterone acetate produce a rise of serum prolactin justifying the use of bromocriptine (or lisuride). Estramustine phosphate should be reserved for relapsing prostatic cancer.

Antineoplastic Agents↗
PubMed1996

Effect of aromatase inhibitor, TZA-2209, on the prostate of androstenedione-treated castrated dogs: changes in prostate volume and histopathological findings.

To determine whether the inhibition of estrogen-related effect in the prostate would be of value in the management of benign prostate hyperplasia (BPH), we examined the effect of TZA-2209, a new steroidal aromatase inhibitor, on the prostate in three of six castrated beagles that received 75 mg/week androstenedione. The three other animals served as controls. Sequential measurements of prostate volume by transrectal ultrasonography showed that the volume in TZA-treated dogs was significantly decreased compared with that in the controls. Prostatic aromatase activity was suppressed by TZA administration. Histopathologically, the stromal component was increased and glands were atrophied by androstenedione treatment. TZA administration increased the volume of the glands. Immunohistochemical detection of estramustine-binding protein showed more positive staining of the protein in the glands that were increased in volume by TZA administration. We concluded that the aromatase inhibitor effectively antagonized the estrogen-related stromal changes, however, this action was accompanied by stimulation of the glandular component due to the accumulation of androgens, the substrate of the aromatase. In the light of these findings, we suggest the simultaneous treatment for the androgen-glandular component route in the prostate is necessary for the effective management of BPH.

Androstenedione↗
PubMed1997

Use of a hormone-sensitive (LNCaP) and a hormone-resistant (LNCaP-r) cell line in prostate cancer research.

BACKGROUND: In order to develop a hormone-resistant analog to the hormone sensitive cell-line LNCaP, different methods were tried. METHODS: After almost one year of continuous culture in RPMI-1640, containing a low concentration of androgens, the hormone sensitive cell-line LNCaP became hormone resistant and was named LNCaP-r. RESULTS: We used the LNCaP/LNCaP-r model system in order to study methods for the parenteral treatment of prostate carcinoma with estrogens, to study the mechanism of action of estramustine, and to identify markers useful as predictive tests for prostate carcinoma. CONCLUSIONS: A model system made up of the hormone sensitive prostate LNCaP cell-line and the hormone resistant LNCaP-r subline was developed and characterized. This system is, despite a number of limitations, easy to use as a first step to test different hypotheses that can be studied further in later clinical trials.

Androgens↗
PubMed1999

Induction of apoptosis and suppression of clonogenicity of ovarian carcinoma cells with estrogen mustard.

BACKGROUND: This study was conducted to evaluate whether estramustine (estrogen mustard [EM]) is a promising alternative in the treatment of patients with epithelial ovarian carcinoma (OVCA). EM is a microtubule-associated protein (MAP) specific antimicrotubule agent with low toxicity. METHODS: The authors investigated the ability of EM to induce apoptosis and suppress colony formation of OVCA cells. Paclitaxel was used as a positive control. DNA electrophoresis and terminal deoxynucleotidyl dUTP-X nick end labeling (TUNEL) assays were used to detect internucleosomal DNA fragmentation. Flow cytometry was used to identify apoptotic cells and disturbance of the cell cycle of EM-treated OVCA cells further. Quantitation of detached cultured cells also provided a relative estimate of the apoptotic response of OVCA cells to treatment with EM. The colony formation assay was used to evaluate the effects of EM on clonogenicity. RESULTS: The effects of EM on four OVCA cell lines in culture were highly similar to those of paclitaxel in causing apoptosis and inhibiting clonogenicity. DNA electrophoresis and TUNEL assays showed that EM induced internucleosomal DNA fragmentation in OVCA cells. Flow cytometry showed changes typical of apoptotic changes and cell cycle block and synchronization at the G2/M-phase. Counting of detached cells showed a log-dose response to EM treatment. The colony formation assay also showed a log-dose response suppression of OVCA cell clonogenicity after treatment with EM. CONCLUSIONS: EM may be a promising candidate in the clinical treatment of patients with OVCA. The lower toxicity and MAP specific action of EM is a novel chemotherapy for OVCA.

Antineoplastic Agents, Alkylating↗
PubMed1992

Different assembly properties of cod, bovine, and rat brain microtubules.

Assembly properties of cod, bovine, and rat brain microtubules were compared. Estramustine phosphate, heparin, poly-L-aspartic acid, as well as NaCl, inhibited the assembly and disassembled both bovine and rat microtubules by inhibition of the binding between tubulin and MAPs. The assembly of cod brain microtubules was in contrast only marginally affected by these agents, in spite of a release of the MAPs. The results suggest that cod tubulin has a high intrinsic ability to assemble. This was confirmed by studies on phosphocellulose-purified cod tubulin, since the critical concentration for assembly was independent of the presence or absence of MAPs. The results show therefore that cod brain tubulin has, in contrast to bovine and rat brain tubulins, a high propensity to assembly under conditions which normally require the presence of MAPs. Even if cod MAPs, which have an unusual protein composition, were not needed for the assembly of cod microtubules, they were able to induce assembly of bovine brain tubulin. Both cod and bovine MAPs bound to cod microtubules, and bovine MAP1 and MAP2 bound to, and substituted at least the 400 kDa cod protein. This suggests that the tubulin-binding sites and the assembly-stimulatory ability of MAPs are common properties of MAPs from different species, independent of the tubulin assembly propensity.

Animals↗