Prostate Cancer: Biology, Incidence, Detection Methods, Treatment Methods, and Vaccines.

Cancer of the prostate are cancers in which most incidences are slow-growing, and in the U.S., a record of 1.2 million new cases of prostate cancer occurred in 2018. The rates of this type of cancer have been increasing in developing nations. The risk factors for prostate cancer include age, family history, and obesity. It is believed that the rate of prostate cancer is correlated with the Western diet. Various advances in methods of radiotherapy have contributed to lowering morbidity. Therapy for hormone- refractory prostate cancer is making progress, for almost all men with metastases will proceed to hormone-refractory prostate cancer. Smoking cigarettes along with the presence of prostate cancer has been shown to cause a higher risk of mortality in prostate cancer. The serious outcome of incontinence and erectile dysfunction result from the cancer treatment of surgery and radiation, particularly for prostate- specific antigen detected cancers that will not cause morbidity or mortality. Families of patients, as well as patients, are profoundly affected following the diagnosis of prostate cancer. Poor communication between spouses during prostate cancer increases the risk for poor adjustment to prostate cancer. The use of serum prostate-specific antigen to screen for prostate cancer has led to a greater detection, in its early stage, of this cancer. Prostate cancer is the most common malignancy in American men, accounting for more than 29% of all diagnosed cancers and about 13% of all cancer deaths. A shortened course of hormonal therapy with docetaxel following radical prostatectomy (or radiation therapy) for high-risk prostate cancer has been shown to be both safe and feasible. Patients treated with docetaxel-estramustine had a prostate-specific antigen response decline of at least 50%. Cancer vaccines are an immune-based cancer treatment that may provide the promise of a non-toxic but efficacious therapeutic alternative for cancer patients. Further studies will elucidate improved methods of detection and treatment.

Estramustine Phosphate Inhibits TGF-ß-Induced Mouse Macrophage Migration and Urokinase-Type Plasminogen Activator Production.

Transforming growth factor-beta (TGF-ß) has been demonstrated as a key regulator of immune responses including monocyte/macrophage functions. TGF-ß regulates macrophage cell migration and polarization, as well as it is shown to modulate macrophage urokinase-type plasminogen activator (uPA) production, which also contributes to macrophage chemotaxis and migration toward damaged or inflamed tissues. Microtubule (MT) cytoskeleton dynamic plays a key role during the cell motility, and any interference on the MT network profoundly affects cell migration. In this study, by using estramustine phosphate (EP), which modifies MT stability, we analysed whether tubulin cytoskeleton contributes to TGF-ß-induced macrophage cell migration and uPA expression. We found out that, in the murine macrophage cell line RAW 264.7, EP at noncytotoxic concentrations inhibited cell migration and uPA expression induced by TGF-ß. Moreover, EP greatly reduced the capacity of TGF-ß to trigger the phosphorylation and activation of its downstream Smad3 effector. Furthermore, Smad3 activation seems to be critical for the increased cell motility. Thus, our data suggest that EP, by interfering with MT dynamics, inhibits TGF-ß-induced RAW 264.7 cell migration paralleled with reduction of uPA induction, in part by disabling Smad3 activation by TGF-ß.

Estramustine phosphate induces prostate cancer cell line PC3 apoptosis by down-regulating miR-31 levels.

OBJECTIVE: Prostate cancer seriously threats to patient's life and health. Estramustine phosphate (EP) is one of the most important drugs in the clinical treatment of prostate cancer. This study aims to explore the molecular mechanism of estramustine phosphate in regulating PC3 cell growth and survive through mediating miR-31. MATERIALS AND METHODS: Estramustine phosphate was used to treat prostate cancer cell line PC3. Flow cytometry was applied to detect PC3 cell growth and apoptosis. RT-PCR was performed to test miR-31 level. Prostate cancer tissue and paracarcinoma tissue were collected to test miR-31 level. PC3 cells were transfected with miR-31 or control microRNA by lipofectamine, and followed treated by estramustine phosphate. RESULTS: PC3 cell appeared growth restrain and apoptosis after treated by estramustine phosphate. MiR-31 level decreased after estramustine phosphate treatment. Prostate cancer tissue presented higher miR-31 level than paracarcinoma tissue. MiR-31 over-expression inhibited estramustine phosphate induced PC3 cell apoptosis. CONCLUSIONS: Estramustine phosphate induces prostate cancer cell line PC3 apoptosis through reducing miR-31.

Estramustine-induced suicidal erythrocyte death.

BACKGROUND: The nitrogen mustard derivative of estradiol-17ß-phosphate estramustine is used for the treatment of prostate cancer. Estramustine may trigger suicidal death of cancer cells. Side effects of estramustine include anemia. At least in theory, estramustine could cause anemia by stimulation of eryptosis, the suicidal death of erythrocytes. Hallmarks of eryptosis include cell shrinkage, increased cytosolic Ca2+ activity ([Ca2+]), ceramide formation and phosphatidylserine translocation to the outer leaflet of the cell membrane with phosphatidylserine exposure at the erythrocyte surface. Eryptosis is stimulated by increase of cytosolic Ca2+ activity ([Ca2+]i). The present study explored whether estramustine triggers eryptosis. METHODS: [Ca2+]i was estimated from Fluo3 fluorescence, cell volume from forward scatter, phosphatidylserine exposure from annexin V binding, and hemolysis from hemoglobin release. RESULTS: A 24 h exposure to estramustine (≤ 100 µM) significantly increased [Ca2+]i, increased annexin V binding and increased hemoglobin release. The effect of estramustine on annexin V binding was significantly blunted by removal of extracellular Ca2+. CONCLUSIONS: Estramustine stimulates both, eryptosis and hemolysis. The estramustine induced translocation of phosphatidylserine to the cell surface is at least partially due to increase of cytosolic Ca2+ activity.

Comparative study of microtubule inhibitors--estramustine and natural podophyllotoxin conjugated PAMAM dendrimer on glioma cell proliferation.

The synthetic estramustine (EM) and natural podophyllotoxin (PODO) anti-mitotic agents that inhibit tubulin polymerization are known anticancer agents. As low bioavailability limits their anticancer properties, we investigated whether conjugation with PAMAM dendrimer (D) could enhance the activity of D-EM and D-PODO by altering their release pattern. Release kinetics indicated synthesized conjugates to be stable against hydrolytic cleavage and showed sustained release characteristics. However, release of D-EM was slow compared to D-PODO conjugate. Antitumor effect of these conjugates on glioma cells revealed (i) increased cell death and cell cycle arrest (ii) decreased migration and (iii) increased tubulin depolymerization as compared to free drug. Importantly, the effects of natural PODO conjugate on glioma cell survival and migration is more pronounced than D-EM.

Shp2 protein tyrosine phosphatase inhibitor activity of estramustine phosphate and its triterpenoid analogs.

Shp2 protein tyrosine phosphate (PTP) is a novel target for anticancer drug discovery. We identified estramustine phosphate as a Shp2 PTP inhibitor from the National Cancer Institute Approved Oncology Drug set. A focused structure-activity relationship study indicated that the 17-phosphate group is required for the Shp2 PTP inhibitor activity of estramustine phosphate. A search for estramustine phosphate analogs led to identification of two triterpenoids, enoxolone, and celastrol, having Shp2 PTP inhibitor activity. With the previously reported PTP1B inhibitor trodusquemine, our study reveals steroids and triterpenoids with negatively charged phosphate, carboxylate, or sulfonate groups as novel pharmacophores of selective PTP inhibitors.

Role of androgen deprivation treatment in patients with castration-resistant prostate cancer, receiving docetaxel-based chemotherapy.

OBJECTIVES: To assess the impact of continued androgen deprivation therapy (ADT) in patients with castration-resistant prostate cancer (CRPC) receiving first-line docetaxel-based chemotherapy. METHODS: A retrospective review was performed on 78 patients fulfilling the criteria for CRPC who were treated with docetaxel-based chemotherapy over 5 years. RESULTS: Thirty-nine patients received concurrent ADT (ADT group), whereas 39 patients discontinued ADT (No-ADT group). PSA response rates were 66.7% for ADT patients and 48.7% for No-ADT patients (P = 0.27). The median progression-free survival and overall survival were 5.0 months and 24.8 months for ADT patients and 4.9 months and 22.1 months for No-ADT patients, respectively (P = 0.57, P = 0.94). Follow-up testosterone levels were available in 13 patients of the No-ADT group and none of them recovered a normal serum testosterone level over a median follow-up duration of 8.3 months from ADT discontinuation. ADT was recommenced in 21 of 39 patients in the No-ADT group and, of these, 6 (29%) achieved a PSA response. CONCLUSION: Clinical outcomes were not significantly different when patients with CRPC received concurrent ADT, or were not so treated, when receiving first-line docetaxel-based chemotherapy. Despite ADT withdrawal, serum testosterone level did not recover to the noncastrated level during the period of chemotherapy, and reinduction of hormone sensitivity occurred in about one-quarter of patients.

A preclinical therapeutic schedule optimizing docetaxel plus estramustine administration in prostate cancer.

Androgen-dependent and castration-resistant prostate cancer (PC) is usually sensitive to docetaxel chemotherapy. Nevertheless, docetaxel resistance frequently appears after several cycles of treatment, raising the problem of salvage treatment for docetaxel-resistant PC patients. Although the combination of docetaxel and estramustine prolongs metastasis-free and overall survival of patients with androgen-independent PC, the use of this modality remains limited in elderly patients or patients with several comorbidities, especially vascular disease or gastrointestinal toxicity, because of unacceptable toxicity including venous thrombosis. The aims of this study were therefore (i) to evaluate the in-vivo efficacy of estramustine combined with docetaxel since initial tumor growth and following the appearance of docetaxel resistance in the androgen-dependent human PC xenograft PAC120, and (ii) to evaluate the efficacy of estramustine in six human androgen-independent PC models derived from PAC120. In docetaxel-resistant tumor-bearing mice, estramustine alone induced a TGD2 of 18 days, whereas the combination of docetaxel and estramustine induced a TGD2 of 50 days (P<0.05) with no significantly different overall survival of mice treated by docetaxel and estramustine since day 1 or since the onset of resistance to docetaxel. Among the six human androgen-independent tumors treated with estramustine alone, two highly sensitive models, two intermediate responding tumors, and two resistant models were observed. Altogether, these results suggest that estramustine should be combined with docetaxel in PC patients, but the use of this treatment could be limited, particularly in elderly patients, to docetaxel-resistant cases.

Kinetic stabilization of microtubule dynamics by estramustine is associated with tubulin acetylation, spindle abnormalities, and mitotic arrest.

Estramustine (EM) alone or in combination with other anticancer agents is clinically used for the treatment of hormone refractory prostate cancer. Furthermore, EM has been shown to potently inhibit the proliferation of different types of cancer cells in culture apparently by targeting microtubules; however, the antiproliferative mechanism of action of EM is not clear. In this work, we have shown that EM strongly suppressed the dynamic instability of individual microtubules in MCF-7 cells by reducing the rates of growing and shortening excursions and increasing the time microtubule spent in the pause state. At its half maximal proliferation inhibitory concentration (IC(50)), EM exerted strong suppressive effects on the dynamics of microtubules in MCF-7 cells without detectably affecting either the organization or the polymerized mass of microtubules. At relatively high concentrations (5 x IC(50)), EM significantly depolymerized microtubules in the cells. Furthermore, the microtubules were found highly acetylated, supporting the conclusion that they were stabilized by the drug. EM treatment induced spindle abnormalities in MCF-7 cells, and a major population of the arrested mitotic cells was multipolar. EM also perturbed the microtubule-kinetochore interaction, thereby activating the spindle assembly checkpoint and leading to apoptotic cell death.

The effect of combined androgen blockade on bone turnover and bone mineral density in men with prostate cancer.

UNLABELLED: Our study and previous reports suggest that castration results in increased bone turnover and lowered BMD and that these changes might be attenuated by anti-androgens, such as BL and EMP. INTRODUCTION: Recent studies have shown that castration for PC decreases bone mineral density (BMD), while estrogen therapy or bicalutamide (BL) monotherapy maintains BMD. However, the effect of combined androgen blockade (CAB) on bone turnover is not well studied. METHODS: A total of 204 men were evaluated in the study (control group: n = 56, castration group: n = 102, 'CAB with BL' group: n = 22, 'CAB with estramustine phosphate (EMP)' group: n = 24). We measured steroid hormone levels, BMD (measured at one-third distal radius), bone turnover markers (levels of urinary N-telopeptide cross links of type 1 collagen (u-NTx) and deoxypyridinoline (u-DPD), serum concentrations of osteocalcin (OC)) in order to assess differences between groups. RESULTS: The BMD % Z score of the castration group was significantly lower than that of the control group or the 'CAB with EMP' group (90.6% vs. 95.5%, 98.6%; p < 0.042, p < 0.044, respectively). Levels of u-NTx, u-DPD, OC of the castration group were the highest followed by the control group, then the 'CAB with BL' group and the 'CAB with EMP' group. CONCLUSIONS: Our study and previous reports suggests that castration results in increased bone turnover and lowered BMD and that these changes might be attenuated by anti-androgens, such as BL and EMP.

Evaluation of lipophilins as determinants of tumor cell response to estramustine.

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.

Radiation sensitizing effect of estramustine is not dependent on apoptosis.

BACKGROUND: Estramustine is an anti-mitotic cytostatic drug that also enhances the effect of radiotherapy. The mechanism of radiosensitization is not thoroughly known. Since both radiotherapy and estramustine induce apoptosis in prostate cancer cells, we conducted an experiment to show whether radiosensitization is mediated by apoptosis. MATERIALS AND METHODS: DU-145 human prostate cancer cells were xenografted to nude mice and treated with estramustine for 2 weeks and external radiation for 3 to 6 days (18 to 36 Gy). Tumor regression was measured mechanically and the rate of apoptosis defined by the amount of low molecular weight DNA fragmentation. Follow-up time was 1 to 18 days. RESULTS: The tumor size regressed in the group of mice receiving both radiotherapy and estramustine. Four weeks after the treatment, apoptosis was accentuated in the tumors treated with estramustine or radiation but not with their combination. CONCLUSION: Estramustine potentiates radiotherapy, but not by enhancing radiation-induced apoptosis.

Influence of p53 and bcl-2 on chemosensitivity in benign and malignant prostatic cell lines.

The administration of cancer chemotherapeutic agents results in an increase in the apoptotic cells in the tumor: therefore, it has been assumed that anticancer drugs exhibit their cytotoxic effects via apoptotic signaling pathways. Characteristics that confer sensitivity to drug-induced apoptosis are, a functional p53 protein and expression of the apoptosis-promoting protein, bax. The role of p53 and bax/bcl-2 in drug-induced apoptosis was assessed in six prostate cell lines, 1532T, 1535T, 1542T, 1542N, BPH-1 and LNCaP using TD(50) concentrations of etoposide, vinblastine and estramustine. Cell death was monitored morphologically by fluorescent microscopy, and by flow cytometry (Annexin-V assay). Apoptotic morphology was rather low and ranged from 0.1% to 12.1%, 3.0% to 6.0% and 0.1% to 8.5% for etoposide, estramustine and vinblastine, respectively. Annexin-V binding and flow cytometry indicated apoptotic propensities of 0% to 4%, 0% to 3% and 0% to 5%, respectively. The percentage of cells responding to drug-induced apoptosis was, on average, higher in the tumor cell lines than in the normal cell lines, but showed no correlation with p53 status. The percentage of cells showing necrosis, assessed by Annexin binding and Propidium Iodide permeability in aqueous medium, tended to be much higher, and was found to be at the level of 5% to 30%. Immunoblotting demonstrated that bax and bcl-2 proteins were expressed at a basal level in all cell lines, but did not increase after exposure to TD(50) doses of the three drugs. The ratio of bax and bcl-2, measured by laser scanning densitometry, was not altered by the drug-induced DNA damage. The results suggest that apoptosis is not a major mechanism of drug-induced cell death in prostate cell lines and appears to be independent of p53 status and bax/bcl-2 expression.

Gene expression profiling revealed novel molecular targets of docetaxel and estramustine combination treatment in prostate cancer cells.

Both docetaxel and estramustine are antimicrotubule agents with antitumor activity in various cancers including prostate cancer. Clinical trials for docetaxel and estramustine combination treatment have suggested improved antitumor activity in hormone-refractory prostate cancer. However, the molecular mechanisms involved in the combination treatment with docetaxel and estramustine have not been fully elucidated. In order to establish such molecular mechanisms in both hormone insensitive (PC-3) and sensitive (LNCaP) prostate cancer cells, gene expression profiles of docetaxel- and estramustine-treated prostate cancer cells were obtained by using Affymetrix Human Genome U133A Array. Total RNA from PC-3 and LNCaP cells untreated and treated with 2 nmol/L docetaxel, 4 micromol/L estramustine, or 1 nmol/L docetaxel plus 2 micromol/L estramustine for 6, 36, and 72 hours was subjected to microarray analysis. Real-time PCR and Western blot analysis were conducted to confirm the microarray data. Clustering analysis based on biological function showed that docetaxel and estramustine combination treatment down-regulated some genes that are known to regulate cell proliferation, transcription, translation, and oncogenesis. In contrast, docetaxel and estramustine combination treatment up-regulated some genes related to induction of apoptosis, cell cycle arrest, and tumor suppression. Docetaxel and estramustine also showed differential effects on gene expression between mono- and combination treatment. Combination treatment with docetaxel and estramustine caused alternations of a large number of genes, many of which may contribute to the molecular mechanisms by which docetaxel and estramustine inhibit the growth of prostate cancer cells. These results provide novel molecular targets of docetaxel and estramustine combination treatment in prostate cancer cells. This information could be utilized for further mechanistic research and for devising optimized therapeutic strategies against prostate cancer.

In vitro cytotoxic effects of imatinib in combination with anticancer drugs in human prostate cancer cell lines.

BACKGROUND: The platelet-derived growth factor receptor (PDFG-r), a tyrosine kinase, is expressed in 88% of primary prostate cancer and in 80% of the metastases. The tyrosine kinase inhibitor imatinib blocks the PDGF signaling pathway by inhibiting PDGF-r autophosphorylation. We examined the cytotoxic effects of imatinib in combination with other anticancer agents in the human prostate cancer cell lines LNCaP, PC-3, and DU 145. METHODS: The cells were exposed to imatinib and to the other drugs simultaneously for 5 days. Cell growth inhibition was determined by XTT assay. The cytotoxic effects in combinations were evaluated at the inhibitory concentration of 50% level by the isobologram. RESULTS: Imatinib produced additive effects with estramustine phosphate (EMP) and 4-hydroperoxy-cyclophosphamide in all three cell lines. In combination with etoposide imatinib produced additive effects in two of three cell lines. Imatinib with docetaxel produced antagonistic effects in PC-3 and additive to antagonistic effects in LNCaP and DU 145 cells. CONCLUSIONS: The simultaneous exposure of imatinib and EMP would be effective against hormone sensitive and hormone insensitive cell lines and this combination should be evaluated in clinical trials. In contrast, the simultaneous exposure of imatinib and docetaxel would have little therapeutic efficacy. Although there are gaps between in vitro studies and clinical trials, the present findings provide useful information for the establishment of clinical protocols involving imatinib in hormone-refractory prostate cancer.

Gene expression profiling reveals novel targets of estramustine phosphate in prostate cancer cells.

Estramustine phosphate (EMP) is a compound widely used for the treatment of hormone-refractory prostate cancer. In order to better understand the precise molecular mechanism(s) by which EMP exerts its effects on hormone-resistant PC3 prostate cancer cells, we have utilized microarray to interrogate 22,215 known genes to determine the gene expression profiles altered by EMP treatment. The purpose of this investigation was to identify gene expression profile first and then in future studies determine the specific role of these genes in EMP-induced apoptosis in prostate cancer cells. We found a total of 726 genes which showed >2 fold change after EMP treatment. Clustering analysis showed 12 different types of expression alteration. These genes were also subjected to cluster analysis according to their biological functions. We found that EMP regulated the expression of genes, which are critically involved in the regulation of cell growth, cell cycle, apoptosis, iron homeostasis, cytoskeleton and cell signaling transduction. Real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis was used to confirm the results of microarray, and the results of real-time quantitative RT-PCR were consistent with the microarray data. From these results, we conclude that EMP caused changes in the expression of a large number of genes that are related to the control of cell survival and physiological behaviors. The gene expression profiles may provide comprehensive molecular mechanism(s) by which EMP exerts its pleiotropic effects on prostate cancer cells. EMP-induced regulation of these genes may be further exploited for devising therapeutic strategies for prostate cancer.

Identification of a novel first exon of the human ABCA2 transporter gene encoding a unique N-terminus.

The human ABCA2 transporter is a member of a large family of ATP-binding proteins that transport a variety of molecules across biological membranes. Using RNA ligation-mediated PCR (RLM-PCR), we have identified a novel first exon, which we designate 1B that is located 699 bp upstream of the previously characterized first exon, which we designate 1A. These first exons are alternatively spliced to the second exon of the ABCA2 transcript resulting in a protein that has a unique amino terminus. For exon 1B, the new amino terminus encoded by the first exon is 52 amino acids and for exon 1A, 22 amino acids. We observed that among adult tissues examined, the highest expression of the 1B isoform was in peripheral blood leukocytes (PBL). Laser scanning confocal microscopy revealed that the 1A isoform and the 1B isoform co-localize with lysosome-associated membrane proteins-1 and -2 (LAMP-1 and -2). Cytotoxicity assays suggested a role for ABCA2 in estramustine and estradiol resistance, and overexpression of ABCA2 is seen in an estramustine-resistant prostate carcinoma line. Since both isoforms of the ABCA2 transporter have identical subcellular localization and both are overexpressed in a resistant cell line, we propose that they are also functionally redundant. It is likely that expression of ABCA2 by two independent promoters constitutes locus of regulation controlling expression of the protein to meet requirements in different tissues.

Pilot study of epothilone B analog (BMS-247550) and estramustine phosphate in patients with progressive metastatic prostate cancer following castration.

BACKGROUND: Several trials have demonstrated that the response proportions to microtubule agents in patients with prostate cancer are increased by the addition of estramustine phosphate (EMP). The epothilone B analog BMS-247550 is a novel microtubule agent that has shown activity in taxane-resistant tumors. We conducted a dose-escalation study to determine a safe dose of BMS-247550 to combine with EMP in patients with metastatic prostate cancer. PATIENTS AND METHODS: Chemotherapy-naive patients with castrate-metastatic prostate cancer were treated with intravenous BMS-247550 and oral EMP (280 mg three times daily for 5 days) every 3 weeks. RESULTS: Thirteen patients were treated at two dose levels (35 and 40 mg/m(2)). Three of six patients treated at 40 mg/m(2) developed grade 4 neutropenia, establishing 35 mg/m(2) as the maximum-tolerated dose. Significant peripheral neuropathy (grade >/= 2) was related to dose level and infusion rate. A decline in prostate-specific antigen (PSA) of >/= 50% was seen in 11 of 12 evaluable patients (92%) (95% confidence interval 76% to 100%). There were objective responses in soft tissue (57%) and bone metastasis (40%). CONCLUSIONS: The phase II dose of BMS-247550 combined with EMP is 35 mg/m(2) over 3 h every 3 weeks. This combination is safe and >/= 50% post-therapy declines in PSA were seen in 11 of 12 patients (92%).

Drug resistance in prostate cancer cell lines is influenced by androgen dependence and p53 status.

Chemotherapeutic drug resistance remains a significant obstacle in the control of prostate cancer. The influence of p53 and androgen status on the drug response of new cell lines from normal, benign and primary tumour epithelium was investigated. The prostate cell lines 1542-NPTX, BPH-1, 1542-CP(3)TX, 1532-CP(2)TX, 1535-CP(1)TX and LNCaP were exposed to TD(50) doses of etoposide, vinblastine and estramustine for a period of 24 h and re-incubated for a further 4 days before measuring the cell viability by crystal violet vital dye staining assay. The virus-transformed cell lines were found to be approximately ten times more sensitive to etoposide and vinblastine than the non virus-transformed LNCaP cell line. Estramustine proved to be the least toxic drug. The LNCaP cell line emerged as DHT-sensitive against nanomolar concentrations of 5alpha-dihydrotestosterone in charcoal-stripped growth medium. The virus-transformed cell lines were DHT-insensitive. Induction of p21 by (60)Co gamma-irradiation was used to assess the functionality of the p53 gene. p21 induction in the LNCaP cell line reached a peak 7.5 h post-irradiation. No significant p21 induction occurred in the virus-transformed cell lines. We show that the androgen-independent tumour cell lines are more sensitive to etoposide and vinblastine than the androgen dependent cell line, LNCaP. Except for LNCaP cells, etoposide and vinblastine were found to be three- to ten-fold more effective than estramustine. In the benign hyperplasia cell line, BPH-1, only etoposide is highly effective. Etoposide and vinblastine were found to effectively inactivate the androgen-independent cell lines, in which p53 is dysfunctional.

Ondansetron but not granisetron affect cell volume regulation and potassium ion transport of glioma cells treated with estramustine phosphate.

PURPOSE: Highly 5-HT(3)-receptor-specific antiemetic agents may have different effects on ion transport of tumour cells during treatment with cytotoxic drugs. Cell volume regulation, which is dependent on potassium ion (K(+)) flux, is involved the control of cell growth, proliferation, and apoptosis. K(+)-flux response mechanisms to the antiemetics ondansetron and granisetron were therefore correlated to malignant glioma cell (Mg251) volume response to estramustine phosphate (EMP) in vitro. METHODS: We quantified the influx and efflux of potassium ions (using the K(+) analogue (86)Rb(+)) as well as cell volume changes (with image analysis) of glioma cells incubated with the 5-HT(3)-receptor antagonists ondansetron and granisetron (0.1 micro mol/l) combined with 40 mg/l EMP. RESULTS: The EMP-induced cell volume increase was fully inhibited by ondansetron but not affected by granisetron. Ondansetron retained high cellular K(+)-efflux and reduced Na(+), K(+), 2Cl(-)-cotransport activity, whereas granisetron (0.1 micro mol/l) reduced K(+)-efflux and retained an augmented Na(+), K(+), 2Cl(-)-cotransport activity in the presence of 40 mg/l EMP. CONCLUSIONS: Ondansetron affects K(+) transport with ensuing effects on cell volume of tumour cells treated with EMP, whereas granisetron does not. Since ondansetron and other 5-HT(3)-receptor antagonists are used routinely to prevent nausea during anticancer treatment, an increased awareness of possible interactions with the antitumour efficacy of anticancer drugs seems warranted.