Parathyroid hormone, but not prostaglandin E2, changes the shape of osteoblasts maintained on bone in vitro.

Parietal bones from 2-week-old rats were dissected free from the sutural regions, dura mater, and periosteum, leaving the surface covered with osteoblasts and some osteoclasts. Prostaglandin (PG) production by these "stripped" bones under basal conditions and after exposure to parathyroid hormone (PTH) was measured by radioimmunoassay of the culture medium (minimum essential medium with or without added 10% heat-inactivated fetal calf serum). Cultured specimens were examined by scanning electron microscopy for changes in osteoblast length, orientation, ruffling, and overlap. As demonstrated previously, PTH caused the osteoblasts to elongate, align, and show fewer ruffles compared to controls. PTH increased PG synthesis by the stripped bones. Indomethacin inhibited PG formation but did not affect the osteoblast shape change. PGE2, indomethacin, or both drugs together had no discernible effect on any morphologic features. These findings indicate that PGE2 does not change osteoblast shape and that the cell shape change with PTH is not mediated by endogenous prostanoids.

Cancer Research Campaign Adjuvant Breast Trial for patients under 50.

The objectives of the Cancer Research Campaign Adjuvant Breast Trial are to determine whether the administration of a course of adjuvant tamoxifen, or ablation of ovarian function, results in a prolongation of time to recurrence or death, for women aged under 50 years and treated for operable breast cancer. The basis and aims of the trial are discussed.

Nitrates do not affect prostacyclin formation by rat arteries: this is unrelated to increased vascular prostacyclin formation with age.

The question of whether vasodilator nitrates act by releasing prostacyclin is controversial. Since the ability of blood vessels to form prostacyclin changes with age, we have investigated whether this may explain the discrepancies in the literature. It does not, since isosorbide dinitrate or glyceryl trinitrate incubated with rat aorta or vena cava from male Wistar rats had little or no effect on the release of prostacyclin, measured as 6-keto-PGF1 alpha. We confirm that the aorta produces substantially more prostacyclin than the vena cava. The arterial production of prostacyclin was greater in rats weighing 350-400 g than in those weighing 116-152 g, but the production by the veins was similar in both groups.

Studies on the mechanism by which indomethacin increases the anticancer effect of methotrexate.

The effect of indomethacin on the response of the NC carcinoma to methotrexate has been examined in vivo and in vitro. Survival was prolonged in mice treated with indomethacin 1.25 mg kg-1 twice daily plus methotrexate 4 mg kg-1 daily, compared to mice given either drug alone or controls. Indomethacin 1 microgram ml-1 increased the killing of cultured NC cells by methotrexate. This was not due to displacement of methotrexate from binding sites on the serum proteins. Nor was it due (entirely) to inhibition of prostaglandin synthesis, since flurbiprofen did not mimic the effect. Inhibition of cyclic AMP phosphodiesterase seems unlikely to explain the effect of indomethacin since theophylline had little or no effect on NC cell killing by methotrexate. Indomethacin 1 microgram ml-1 increased the accumulation of tritium in NC cells incubated with [3H]-methotrexate. In contrast, with normal epithelial cells from human embryonic intestine, indomethacin 1 microgram ml-1 did not alter the cytotoxicity of methotrexate or the accumulation of tritium during incubation with [3H]-methotrexate. The beneficial interaction between indomethacin and methotrexate may have therapeutic potential in man.

Cancer in mice: effects of prednisolone or mepacrine alone and with cytotoxic drugs.

WHT/Ht mice were transplanted s.c. with NC carcinoma, and the tumours were excised after 2 weeks. The mice were treated orally throughout the experiments with prednisolone 500 micrograms kg-1 or mepacrine 3.6 mg kg-1, starting the day after tumour transplantation or, with prednisolone, the day after tumour excision. In some experiments the mice were also treated with the cytotoxic drugs methotrexate 2 mg kg-1 and melphalan 1.4 mg kg-1. The excised tumours were weighed; some of them, and samples of serum, were extracted for prostanoids which were measured by radioimmunoassay. The chemotherapy lengthened the survival of the mice, but prednisolone or mepacrine had little or no effect on survival, metastasis, the response to chemotherapy, tumour size or the formation of tumour prostanoids.

Measurement of arachidonate and its metabolites extracted from human normal and malignant gastrointestinal tissues.

This is the first report of human gastrointestinal arachidonate and prostanoids measured quantitatively by gas chromatography-mass spectrometry (GC-MS) in extracts of human cancers and macroscopically normal tissues from the stomach and colon. There were microgram/g amounts of arachidonate, and the particularly high yield from the tumours may explain why they usually produce more prostaglandins than the normal tissues in which they arise. There was only a small conversion of the arachidonate into prostanoids. 6-Keto-PGF1 alpha was the most abundant metabolite measured, particularly in the tumour extracts, with smaller amounts of prostaglandins E2, F2 alpha and D2.

Survival of mice with NC carcinoma is unchanged by drugs that are thought to inhibit thromboxane synthesis or increase prostacyclin formation.

Mice transplanted with NC carcinoma were treated with the thromboxane synthetase inhibitor dazmegrel (UK38485) or with nafazatrom (BAY G 6575), a compound that is reported to increase prostacyclin formation. Some experiments included the cytotoxic drugs methotrexate and melphalan. The tumours were excised under anaesthesia on day 14 or day 21 after transplantation, and weighed; some were extracted for prostanoids which were measured by radioimmunoassay. Mouse survival time was determined up to day 121, and cancer spread was determined by postmortem examination. The survival was increased by methotrexate and melphalan but not by the other drugs. Nafazatrom-treated mice tended to have lighter tumours. Although dazmegrel reduced the formation of thromboxane B2 during clotting of blood from normal mice, it did not affect the tumour yields of prostanoids. Nafazatrom had no effect on serum or tumour prostanoids. There were no obvious effects of the treatments on the recurrence of tumour in the excision scar, lung metastasis or spread to lymph nodes.

Carbenoxolone and deglycyrrhized liquorice have little or no effect on prostanoid synthesis by rat gastric mucosa ex vivo.

Rats were given either carbenoxolone 50 mg kg-1, deglycyrrhized liquorice 1 g kg-1 or vehicle by gastric tube. The doses were repeated 16 h later, and the stomachs removed after another 2 h. The amounts of prostaglandin E (PGE), 6-keto-PGF1 alpha and thromboxane B2, measured by radioimmunoassay in extracts of the gastric corpus and antrum mucosa, were similar in the treated animals and the controls. We conclude that in rats, carbenoxolone and deglycyrrhized liquorice may exert their anti-ulcer effect by a non-prostaglandin mechanism. This contrasts with the mechanism through to occur in man with carbenoxolone.

Treatment of mouse carcinoma in vivo with a prostaglandin E2 analogue and indomethacin.

WHT/Ht mice transplanted s.c. with NC carcinoma were treated with 16,16-dimethyl prostaglandin E2 methyl ester (di-me-PGE2) and/or indomethacin. Each primary tumour was excised under anaesthesia 3 weeks after transplantation, weighed and extracted for prostaglandins. Mouse survival time and tumour recurrence were measured. Di-me-PGE2 10 micrograms, injected at the tumour site on alternate days from day 1 to 19, indomethacin 2.5 mg kg-1 daily by mouth, or both drugs together resulted in lighter tumours (respectively 45, 45 and 52% less, n = 18 to 20 per group, P less than 0.02) compared with vehicle-treated controls. Indomethacin reduced the tumour prostaglandin yield, but the biological activity in extracts of tumours from mice given di-me-PGE2 was high. The median survival time was longer in mice receiving indomethacin alone (61 days from tumour transplantation compared with 50 days in controls P less than 0.02). Di-me-PGE2 alone had little or no effect on survival (median 48 days) but counteracted the increase with indomethacin (di-me-PGE2 + indomethacin, 49 days median survival). There were no obvious effects of the treatments on tumour recurrence at the excision site, but there was a higher incidence of involved lymph nodes in mice given di-me-PGE2.