Estrone conversion rates by human endometrial cancer cell lines.

Studies on estrone metabolism by long term human endometrial cancer HEC-1A and Ishikawa cell lines are reported. These cell lines grow well in epithelial mono or plurilayer form, as previously reported. Ishikawa cells appear to be estrogen responsive whereas HEC-1A appear non responsive. In our experience Ishikawa cells show high affinity--low capacity estrogen binding sites in both soluble and nuclear fractions of the same range of ZR 75-1 and of MCF7, but HEC-1A cytosols gave Kd values in the order of 10(-8)-10(-9). These values are probably more representative of estrogen receptors of low affinity-high capacity (site II) and this is in agreement with previous results regarding their poor response to estrogens. These two different endometrial cancer cell lines exhibit at the same time, common and quite dissimilar metabolic patterns of estrogens. In fact, metabolic conversion studies carried out after 24th incubation at not far from physiological concentrations by using high pressure liquid chromatography in reverse phase mode plus "on line" radioactive detection showed: Both these well established cell lines are fast growing in culture with sufficient morphological or biochemical stability, at least during a limited number of passages and appear a useful material for studies on steroid metabolism. In both, estradiol (E2) and estrone (E1) were most part of converted products (more than 95%); negligible amounts of other radio-metabolites were observed. Quite different conversion rates of E1 to E2 have been shown by HEC-1A cells (6 times or more), with respect to Ishikawa.