The effect of progesterone and tamoxifen on EGF-dependent activation of phospholipid turnover in uterine and breast tumor cells

• Published in: Biokhimiia (Moscow, Russia) Vol. 58; no. 6; p. 967
• Main Authors: Krasil'nikov, M A, Shatskaia, V A, Bassalyk, L S
• Format: Journal Article
• Language: Russian
• Published: Russia (Federation) 01-06-1993
• Subjects: Adenocarcinoma - metabolism; Breast Neoplasms - metabolism; Chromatography, Thin Layer; Epidermal Growth Factor - pharmacology; Estradiol - pharmacology; Female; Humans; Phospholipids - metabolism; Phosphorus Radioisotopes; Progesterone - pharmacology; Tamoxifen - pharmacology; Tetradecanoylphorbol Acetate - pharmacology; Tumor Cells, Cultured; Uterine Neoplasms - metabolism
• ISSN: 0320-9725

The in vitro effects of the epidermal growth factor (EGF) and progesterone on phospholipid turnover in cells of 19 human adenocarcinomas (postsurgical material) have been studied. In 58% of tumours EGF increased the 32P incorporation into two basic cell phospholipids--phosphatidylcholine and phosphoinositides. In EGF-insensitive cells progesterone induced no noticeable changes in the basal level of phospholipid metabolism. However, in 10 out of 11 positively responding to EGF adenocarcinomas progesterone inhibited the EGF-dependent activation of 32P incorporation into the phospholipids already on the 15th min after its addition to the cells. Analysis of effects of EGF and the anti-estrogen drug tamoxifen on phospholipid turnover in 22 human mammary tumours did not reveal any significant differences in tamoxifen effect on tumour cells differing in their sensitivity to EGF. Independently of cell sensitivity to EGF, tamoxifen caused some decrease in the 32P incorporation into phosphatidylcholine but increased the label incorporation into phosphoinositides. Tamoxifen added to tumour cells prestimulated with EGF or 17 beta-estradiol failed to abrogate the effect of these compounds on phospholipid turnover. At the same time, treatment of cells with the protein kinase C activator 12-O-tetradecanoyl-phorbol-13-acetate fully inhibited the effect of tamoxifen on phospholipid metabolism. The results obtained suggest that the EGF-dependent activation of intracellular phospholipid turnover is under the negative control of progesterone. As for tamoxifen, its effect on cells is independent of EGF and consists, apparently, in the inhibition of protein kinase C activity.