Estrogen metabolism in primary kidney cell cultures from Syrian hamsters

Estrogen metabolism was evaluated in freshly isolated kidney and liver microsomes and in primary kidney cell cultures from Syrian hamsters, a potential experimental model for examining the possible role(s) of estrogens in tumor initiation and development. Initial velocity studies of the conversion of estradiol to 2-hydroxyestradiol, as determined by the 3H2O release assay with the substrate [2-3H]estradiol, resulted in similar apparent Kms of estrogen 2-hydroxylase of 2.85 and 6.25 microM for liver and renal microsomes, respectively. The apparent Vmax for freshly prepared liver microsomes was 0.13 nmol.mg-1.min-1, while that for renal microsomes was 0.040 nmol.mg-1.min-1. Evaluation of estrogen metabolism was also performed in primary cell cultures of hamster kidney cells, consisting of 75% epithelial cells. [6,7-3H]Estradiol (10 microM) was incubated for 0, 24 and 48 h in primary kidney cell cultures, and the organic soluble metabolites analyzed by reverse-phase HPLC. The cultures from untreated, castrated hamsters metabolize [3H]estradiol to yield small quantities of estrone and significant amounts of polar metabolites, while no catechol estrogens were isolated. Estrogen metabolism by diethylstilbestrol-treated (DES-treated) hamster kidney cell cultures also provided small quantities of estrone and no evidence of catechol estrogens. Additionally, larger amounts of additional polar metabolites were isolated in the cultures from DES-treated hamsters. Finally, levels of estrogen 2-hydroxylase were detected in these cultures using the 3H2O release assay. Thus, the short-term primary kidney cell cultures from the Syrian hamster are capable of metabolizing estrogens. Furthermore, the enzymatic processes appear to be available for the conversion of any catechol estrogens formed into more polar metabolites. These investigations in intact cells, capable of performing all biochemical processes, complement both in vivo and subcellular biochemical studies and may aid in elucidating the roles of estrogens and estrogen metabolism in the initiation and development of estrogen-induced, estrogen-dependent kidney tumors in the Syrian hamster.