TY - JOUR
T1 - Metabolism of the liver tumor promoter ethinyl estradiol by primary cultures of rat hepatocytes
AU - Standeven, Andrew M.
AU - Shi, Yuenian E.
AU - Sinclair, Jacqueline F.
AU - Sinclair, Peter R.
AU - Yager, James D.
N1 - Funding Information:
The authors thank Nadia Gorman and Dr. R. Lam-brecht for expert HPLC guidance, Dr. J. Silverman for helpful advice, and Dr. W. Slikker and Dr. Joanne Zurlo for critical comments on the manuscript. This work was supported by NC1 Grant CA-3670 1 to J.D.Y. and Cancer Center Core Support Grant CA-23 108 to the Norris Cotton Cancer Center. A.M.S. received support from NIEHS Training Grant BS07 104 and a NSF Graduate Fellowship. Y.E.S. was supported by a Friends of the Norris Cotton Cancer Center Predoctoral Fellowship.
PY - 1990/3/1
Y1 - 1990/3/1
N2 - Previously, we reported that relatively high micromolar concentrations of the liver tumor promoter 17α-ethinyl estradiol (EE2) stimulated DNA synthesis and enhanced the DNA synthetic response to epidermal growth factor (EGF) in primary cultures of female rat hepatocytes [J. D. Yager, B. D. Roebuck, T. L. Paluszcyk, and V. A. Memoli, Carcinogenesis 7, 2007-2014 (1986); Y. E. Shi and J. D. Yager, Cancer Res. 49, 3574-3580 (1989)]. In this study, our goal was to examine the metabolism of EE2 in cultured hepatocytes. After 4, 24, and 48 hr of culture, hepatocytes maintained their ability to convert up to 95% of a 4 nm concentration of [3H]EE2 to polar conjugates within 4 hr. EE2 at 2 μm was also 95% metabolized within 4 hr. HPLC analysis of the metabolites confirmed the rapid disappearance of [3H]EE2 and the formation of polar conjugates as detected by organic extraction. HPLC separation of hydrolyzed conjugates indicated that the major aglycone was the parent compound, EE2. In general, the metabolites differed both qualitatively and quantitatively from those reported in vivo in the rat. The rapid metabolism of EE2 by hepatocytes in culture may, at least in part, explain the high concentrations of EE2 required to stimulate DNA synthesis in cultured hepatocytes and to potentiate the response to EGF.
AB - Previously, we reported that relatively high micromolar concentrations of the liver tumor promoter 17α-ethinyl estradiol (EE2) stimulated DNA synthesis and enhanced the DNA synthetic response to epidermal growth factor (EGF) in primary cultures of female rat hepatocytes [J. D. Yager, B. D. Roebuck, T. L. Paluszcyk, and V. A. Memoli, Carcinogenesis 7, 2007-2014 (1986); Y. E. Shi and J. D. Yager, Cancer Res. 49, 3574-3580 (1989)]. In this study, our goal was to examine the metabolism of EE2 in cultured hepatocytes. After 4, 24, and 48 hr of culture, hepatocytes maintained their ability to convert up to 95% of a 4 nm concentration of [3H]EE2 to polar conjugates within 4 hr. EE2 at 2 μm was also 95% metabolized within 4 hr. HPLC analysis of the metabolites confirmed the rapid disappearance of [3H]EE2 and the formation of polar conjugates as detected by organic extraction. HPLC separation of hydrolyzed conjugates indicated that the major aglycone was the parent compound, EE2. In general, the metabolites differed both qualitatively and quantitatively from those reported in vivo in the rat. The rapid metabolism of EE2 by hepatocytes in culture may, at least in part, explain the high concentrations of EE2 required to stimulate DNA synthesis in cultured hepatocytes and to potentiate the response to EGF.
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U2 - 10.1016/0041-008X(90)90044-U
DO - 10.1016/0041-008X(90)90044-U
M3 - Article
C2 - 2315917
AN - SCOPUS:0025257301
SN - 0041-008X
VL - 102
SP - 486
EP - 496
JO - Toxicology and Applied Pharmacology
JF - Toxicology and Applied Pharmacology
IS - 3
ER -