Changes in lipid profiles of estrogen-induced and transplanted renal carcinomas in Syrian hamsters.

The lipid profiles of estrogen-induced primary renal carcinomas and hormone-dependent and -independent transplanted tumors were compared with those of both normal hamster kidneys and renal tissues of tumor-bearing animals. Autonomous tumors had only one-third the amount of triglycerides present in normal kidneys and hormone-dependent tumors contained intermediate levels. Host kidneys of animals bearing either primary or transplanted tumors contained no more than 50-60% of the triglyceride level found in normal kidneys. In contrast to triglycerides, cholesteryl esters in primary tumors were 200 times higher than in normal kidneys, exhibited a successive decline in hormone-dependent and -independent tumors, but remained 15 times higher in autonomous carcinomas than in normal kidneys. Cholesterol levels were similar in primary tumors, normal kidneys, and host kidneys of animals bearing renal tumors; however, both hormone-dependent and -independent neoplasms had only one-half to two-thirds as much cholesterol as normal kidneys. Total phospholipid levels in primary and transplanted carcinomas were about one-half those in normal kidneys. Host kidneys of animals bearing primary and transplanted, hormone-dependent neoplasms also contained lower phospholipid levels than normal kidneys, but renal tissues from animals with autonomous tumors contained similar levels to those found in kidneys from normal hamsters. The phospholipid composition of primary and transplanted renal tumors was similar, but different from that of normal kidneys, mainly in increased percentages of phosphatidylcholine and decreased percentages of sphingomyelin.

Increased progesterone receptor concentrations in bladder lesions of estrogen-treated Syrian hamsters.

During studies of renal tumorigenesis induced by estrogen in Syrian hamsters, we have observed that about 15 to 20% of animals develop bladder lesions with an increased wet weight of tissue from 0.2 g to 0.4 to 1.7 g. Histological examination of the lesions showed a spectrum of changes from inflammatory reactions to squamous metaplasia and intense hyperplasia of the transitional epithelium. The concentration of progesterone-binding sites was increased in the bladders with lesions. No specific progesterone-binding sites could be detected in the cytosol of bladders from hamsters not treated with estrogen. The affinity constant for the progesterone-binding sites in cytosol from bladders with lesions was 10(9) M-1, the same as that reported for progesterone receptors in other target tissues for estrogen. The binding sites are specific for progesterone and are not competed for by 17 beta-estradiol, 5 alpha-dihydrotestosterone, or aldosterone.

Changes in estrogen receptor levels during deciduomata development in the pseudopregnant rat.

The presence of a cytoplasmic estradiol receptor with an affinity constant of 10(10)M-1 has been demonstrated in the differentiated fibroblasts comprising the deciduomata in pseudopregnant rats. The receptor had a sedimentation coefficient of 6S in sucrose density gradients containing a physiological concentration of salt, and estradiol binding was completely abolished by a hundred-fold excess of unlabeled estradiol. During the early stages of decidualization (days 2 and 3), the decidualized uterine horn or isolated deciduomal tissue contained a concentration of receptor comparable to that in non-gravid uteri from rats ovariectomized at estrus. By day 5 of decidualization, the concentration of estradiol binding in deciduomal tissue decreased to about one-half the concentration measurable at days 2 and 3 of decidualization despite continued tissue growth until day 7. By day 7 of decidualization, estradiol binding had decreased to about 20% of the concentration on days 2 and 3 of decidualization. Cytosol from untreated uterine horns of rats bearing deciduomata bound the same amount of estradiol through day 7 as that in uteri of rats ovariectomized at estrus. These observations are discussed in terms of steroid hormone involved in deciduomal growth and regression.

Changes in progesterone receptor levels during deciduomata development in the pseudopregnant rat.

A specific cytoplasmic progesterone receptor has been identified and quantified in the deciduomata of the pseudopregnant rat. The receptor had a sedimentation coefficient of 6-7S on sucrose density gradients and was inactivated by proteolytic enzymes, sulfhydryl blocking agents and elevated temperature. The equilibrium association constant for the binding of progesterone by the deciduomal receptor was determined to be approximately 10(9)M-1. The concentrations of progesterone receptor sites in cytosols prepared from deciduomata on day 3 and 5 of decidualization were 3.4 +/- 0.3 X 10(-10)M and 3.6 +/- 0.4 X 10(10)M, respectively, when normalized to a protein concentration of 1 mg/ml. These concentrations of progesterone receptor sites were similar to that measured in the uterine cytosol of estrous rats or in the contralateral untreated uterine horn of rats undergoing decidualization. Following day 5 of decidualization the concentrations of progesterone receptor sites decreased linearly so that by day 7 the concentration was approximately one-half that at days 3 and 5. The physiological significance of the progesterone receptor and the decrease in its concentration with time are discussed with regard to their influence on the decidualization reaction.

Receptor characteristics of specific estrogen binding in the renal adenocarcinoma of the golden hamster.

Linear sucrose gradient analyses reveal that all estrogen-induced and -dependent primary renal tumor cytosols examined contain an 8 S and variable amounts of 4 S receptor in low ionic buffer concentrations. Similar results were obtained with extracts of primary metastases of these tumors. Sucrose gradients containing high salt (0.4 M KCl) convert the 8 S receptor in both the hamster renal tumor and uterus to a 4 to 5 S complex. Scatchard plot analysis reveals that the renal tumor cytosol estradiol-receptor complex has a Ka of 1.7 X 10(9) M-1 and 9.2 X 10(-10) M binding sites. Competition for the tritiated 17beta-estradiol binding sites in the renal tumor was similar to that in the uterus with respect to estrogenic compounds. Nonestrogenic steroids exhibited minimal competition at the same concentrations or higher. Substitution in the ring structure, particularly in position 3 of the phenolic A-ring, resulted in a considerable loss in the ability of such compounds to compete for these receptors. Aniestrogens were effective competitors for these estrogen receptors only at higher concentrations relative to the tritiated estradiol.

Biochemical comparison of estrogen receptors of the hamster hypothalamus and uterus.

Comparison of the soluble estradiol receptor proteins in the hypothalamus and uterus of the golden Syrian hamster revealed that both have sedimentation coefficients of 8S in a low ionic strength buffer and migrate similarly on analytical disc-gel electrophoresis in both 5% and 7% acrylamide gels. The competition of [3H]-17beta-estradiol binding by unlabeled estrogenic as well as nonestrogenic compounds was similar with the receptors present in the two tissues. The affinity constants for the hypothalamic and uterine receptors were 4.3 X 10-9M-1 and 1.6 X 10-10M-1, respectively; the number of binding sites when expressed on an equivalent protein basis (i.e. 1 mg/ml) was 0.18 X 10-10M and 3.1 X 10-10M, respectively. Identical amounts of soluble receptors with similar sedimentation characteristics were found in hypothalami from male and female animals gonadectomized 64 h prior to use. A titration of binding sites in the uteri of intact and ovariectomized animals revealed decreased binding in the supernatant preparation from intact animals, probably due to the presence of bound endogenous unlabeled hormone.