Ethinylestradiol and d-norgestrel regulation of plasminogen activator in a human melanoma cell line

The influence of ethinylestradiol (EE2) and d-norgestrel (d-Ng) was studied in a melanoma cell line producing a tissue-type plasminogen activator (t-PA) very similar to or identical with the t-PA isolated in extracts from human uterus. The cell cultures were exposed to the two contraceptive steroids by addition of EE2 or d-Ng dissolved in a week alcoholic solution to the culture media, in which the released t-PA was assayed by an immunoradiometric method. A strongly stimulating effect of ethanol (0.76% w/v) on the t-PA production was demonstrated. Whereas, EE2 in the concentration of 1.7 X 10(-7)M and d-Ng in the concentration of 8.6 X 10(-7)M both caused a significantly reduced secretion of t-PA, and this effect was independent of whether the cell cultures were grown to confluency in the presence of the two synthetic steroids or not. It was concluded, that the two contraceptive steroids had an inhibitory effect on the production of t-PA in melanoma cell culture.