Beryl Hartley-Asp

Growth and cell survival following treatment with estramustine nor-nitrogen mustard, estradiol and testosterone of a human prostatic cancer cell line (DU 145).

Estramustine at concentrations ranging from 3-40 x 10(-6) M inhibited the cell growth and clonogenic survival of a human prostatic carcinoma cell line (DU 145). This cell line was found to be unresponsive to estradiol and testosterone at concentrations ranging from 10(-9) M to 5 x 10(-5) M. Metabolism studies with estramustine showed that only a few per cent of the ester linkage was cleaved during the exposure period. This small amount of metabolism could possibly lead to the release of nor-nitrogen mustard, which was however found not to be as inhibitory as estramustine in this cell line. The results indicate that estramustine per se causes the cell death of hormone unresponsive human prostatic carcinoma cells in cell culture.

Effects of potential aneuploidy inducing agents on microtubule assembly in vitro.

The present study was carried out with the 10 known or suspected spindle poisons of the Commission of the European Communities program to study aneuploidy induction. We have investigated these substances on the assembly of isolated bovine microtubules at 10, 100 and 1000 microM and studied morphology by electron microscopy. The substances could be grouped into two categories, strong and weak inhibitors. Colchicine, vinblastine and thimerosal were strong inhibitors; cadmium chloride, thiabendazole, chloral hydrate, hydroquinone, diazepam and econazole were weak inhibitors, the latter three causing aberrant forms visible on electron microscopy. Pyrimethamine did not inhibit the assembly of microtubules, but produced aberrant forms.

Phase I Clinical and Pharmacologic Trial of Intravenous Estramustine Phosphate

PURPOSE To determine the dose-limiting toxicities, maximum-tolerated dose, and pharmacokinetics of intravenous estramustine phosphate (IV EMP). PATIENTS AND METHODS A total of 31 patients with hormone-refractory prostate cancer received IV EMP as a 30- to 90-minute infusion weekly (n = 28) or for 3 consecutive days followed by a single weekly dose (n = 3). IV EMP dose was escalated from 500 to 3,000 mg/m(2). Pharmacokinetics of EMP and the metabolites estramustine (EaM), estromustine (EoM), estradiol, and estrone were assessed after weeks 1 and 4 of treatment. RESULTS The initial IV EMP infusion caused perineal discomfort that was ameliorated by lengthening the infusion time. Other common toxicities were grade 1 to 2 hepatotoxicity, nausea or vomiting, and fatigue or malaise. Lower-extremity thrombosis occurred in one patient, and two others developed upper-extremity thrombosis associated with venous infusion catheters. Dose-limiting fatigue and hypotension occurred at 3,000 mg/m(2), and cumulative fatigue developed after multiple cycles at 2,500 mg/m(2). Mean EMP clearance, estimated steady-state volume of distribution, and elimination half-life were 3.7 L/h, 10.6 L, and 3.7 hours, respectively. Variability of EMP clearance was 21%, and variation in area under the curve per dose for the metabolites was 28% to 36%. Elimination half-lives of EoM and EaM were 110 hours and 64 hours, and peak plasma concentrations of these active metabolites exceeded 10 micromol/L after IV EMP doses greater-than-or-equal 2,000 mg/m(2). CONCLUSION High-dose IV EMP can be administered safely as a weekly short infusion to patients with HRPC. High peak concentrations of active metabolites after IV EMP may provide an advantage over oral EMP in antimicrotubule drug combinations.

Cytotoxicity and metabolism of prednimustine, chlorambucil and prednisolone in a Chinese hamster cell line

SummaryPrednimustine and chlorambucil induce dose-and time-dependent cell death in V79 Chinese hamster cells in vitro. Prednimustine was found to be 3–4 times more potent than either chlorambucil or an equimolar mixture of its components chlorambucil and prednisolone after 24 h treatment.Prednimustine was hydrolyzed to prednisolone and chlorambucil in the system, and the concentration of prednimustine was reduced by one half within 15 h. Prednisolone was not further metabolized, but chlorambucil was rapidly inactivated by dechlorination, the half-life being 2.5 h. No dechlorinated prednimustine was formed during the experiments. The higher stability of prednimustine than chlorambucil is probably due to protective binding to different serum proteins from those that bind chlorambucil.Substitution of fetal calf serum by human serum albumin revealed that hydrolysis of prednimustine is catalyzed by esterases present in the serum. In similar substitution experiments cell survival studies indicated that prednimustine itself was not cytotoxic. Rather, cytotoxicity was found to correlate with hydrolysis to chlorambucil. Thus, it appears that the prolonged availability of chlorambucil is responsible for the increased potency of prednimustine in this system.

The influence of caffeine on the mitomycin C-induced chromosome aberration frequency in normal human and xeroderma pigmentosum cells

The clastogenic effect of mitomycin C (MC) was determined in two normal fibroblast cell lines and two xeroderma pigmentosum (XP) cell lines, a variant and a group A excision-deficient line. The group A xeroderma cell line was substantially more sensitive to MC than either the XP variant or the normal human cells. On caffeine post-treatment potentiation of the MC-induced aberration frequency occurred in all the cell lines. The XP variant cell line exhibited a distinctly higher sensitivity to caffeine than the classical XP or the normal human cell line.

Distribution and metabolism of estramustine in HeLa cells and the human prostatic tumour cell line 1013L

The metabolism of estramustine [estradiol-3-N-bis(2-chloroethyl) carbamate] was investigated in the human prostatic tumour cell line 1013L and the human cervix tumour cell line HeLa S3. Uptake studies revealed that estramustine (EM), and its 17-ketoanalogue estromustine (EoM), differed in their nuclear binding pattern in 1013L cells but not in HeLa cells. Most of the nuclear radioactivity from both EM and EoM was found in the fraction containing the majority of the phospholipids. HPLC studies on EM-treated 1013L cells showed the presence of the oxidized metabolite EoM, in the medium, an enrichment of estradiol and estrone in whole cells and EM and EoM bound to the nuclear protein matrix. Similar studies on the HeLa cell line showed a completely different pattern, no metabolites other than EoM were found in the cell medium and whole cells but several very lipophilic metabolites were found bound to the nuclear protein matrix. On investigation of other tumour cell lines these metabolites were found to be unique to HeLa cells. The results extend our knowledge concerning EM and demonstrate that the cell line 1013L is a relevant model system for studying drugs active against human prostatic tumours.