Alterations in human endometrial protein synthesis during the menstrual cycle and in progestone-stimulated organ culture

Progestin regulation of protein synthesis in endometrial cancer

Protein synthesis in cancerous and normal human endometrium was investigated by the incorporation of [35S]methionine and analysis of products by two-dimensional polyacrylamide gel electrophoresis. Comparison of the cellular products from organ cultures of endometrial carcinoma, obtained from each subject before and after in vivo administration of medroxyprogesterone acetate (MPA) for 10-14 days revealed: (i) a decrease in the synthesis of tubulin and of a protein of molecular weight (mol. wt) 68 kDa, isoelectric point (pI) 6.0, and (ii) an increase in the synthesis of creatine kinase (CK) and of protein of mol. wt 36 kDa, pI 4, following MPA therapy. The 68 kDa protein was expressed at relatively reduced levels in organ cultures of normal human endometrium throughout the menstrual cycle. In primary cultures of normal human endometrium throughout the menstrual cycle. In primary cultures from cancerous endometrium endometrium established for several weeks the 68 kDa protein was not expressed but could be induced by heatshock. Primary cultures were also used to investigate the early events following progesterone stimulation which revealed a decrease in synthesis of a protein mol. wt 36 kDa, pI 8 at 8 h following administration.

The effect of estradiol valerate and allylestrenol on endometrial transformation in hypergonadotropic hypogonadic women

The effect of estradiol valerate and allylestrenol on the endometrial transformation of five hypergonadotropic hypogonadic women was evaluated. Estradiol valerate was administered throughout the whole induced cycle (28 days), while allylestrenol was added during the second half of the cycle. Endometrial biopsies were performed during allylestrenol treatment and were evaluated histologically. Samples of endometrium were also subjected to one-dimensional SDS electrophoresis. Of ten biopsies performed, only one was interpreted to be in-phase, while the others were dated proliferative (4 biopsies) or showed abortive or out-of-phase secretory transformation. The highest mean serum progesterone level, detected under allylestrenol treatment, was 1.5 ng/ml. Protein electrophoresis demonstrated relative sequential changes in the protein patterns of the 115 kDa and 150 kDa protein bands. It is concluded that allylestrenol, although having gestagen properties, may not be efficient for the induction of an adequate secretory transformation of human endometrium in the absence of ovaries.

Progesterone induces a secretory protein in cultured rabbit endometrial stromal cells

Secretion of newly synthesized proteins by rabbit endometrial stromal cells in culture was studied. Progesterone (P) stimulated the synthesis and secretion of a protein with a mol. wt of approx 62 K and a pI of 6.5-7.0. Induction of 62 K protein synthesis was dose dependent; addition of 10 nM P to primary cultures caused a 2-fold or greater increase in the amount of this protein in the medium while addition of 1 microM P resulted in a 4.3-fold increase. Synthesis of this 62 K protein was not induced by estradiol, dexamethasone, or testosterone, nor was progesterone stimulation of the protein modified by estradiol. Thus, induction appears to be specific for a progesterone receptor mediated effect. Synthesis and secretion of this protein in the culture system described is potentially useful as a progestin bioassay.

Identification of a uteroglobin-like antigen in human uterine washings

A uteroglobin-like molecule was detected with a sensitive radioimmunoassay for rabbit uteroglobin in the uterine washings of women. This antigen was detectable only in small amounts in the uterine washings obtained from women in the late luteal phase or proliferative phase, but was detected in large amounts in uterine washings of women collected during the early and midluteal phases of the ovarian-menstrual cycle. Our findings suggest that antigenically similar portions of rabbit uteroglobin have been phylogenetically conserved in women, and that endometrial production and secretion of this human uteroglobin-like antigen may be hormonally regulated.

Protein synthesis and secretion by the human endometrium and decidua during early pregnancy

To investigate the role of the endometrium in sustaining early pregnancy, specimens of endometrium from early pregnancy were incubated in vitro with radiolabelled amino acids, and protein synthesis and secretion were studied by subsequent fluorographic analysis of one-and two-dimensional polyacrylamide gels. Seventeen secreted endometrial proteins (EP) were identified. Changes were demonstrated in the rate of synthesis and/or secretion of a number of these proteins during early pregnancy. Two proteins, EP 14 and EP 15, are the principal secretory proteins of pregnancy endometrium. EP 14 (subunit mol. wt 32 000) is associated with decidualized endometrium and its rate of synthesis/secretion increases during early pregnancy. EP 15 (subunit mol. wt 28 000) is also synthesized and secreted by the secretory endometrium during the menstrual cycle, and during early pregnancy, but its secretion declines to undetectable levels by week 15-16. These proteins may provide useful markers of endometrial function and differentiation during the menstrual cycle and pregnancy.

Morphological characteristics and protein profile of isolated human decidual cells

Isolated decidual cells were prepared from human decidual tissue obtained during early pregnancy by digesting the tissue fragments with 0.1% collagenase solution. Morphological studies of the cells were carried out using morphometric and flow cytometric analysis while the protein profile was analysed by polyacrylamide gel electrophoresis and gel filtration column chromatography. An average of 90% cell viability was achieved and the results showed that decidual cells constitute up to 70% of cell number and 89% of cell area of the isolated decidual cell suspension. The presence of serum proteins in uterine tissue extracts is due to blood contamination. However, the similarities of the non-serum protein profiles in tissue and cellular extracts validates previous studies performed in uterine fluids and tissue extracts. Finally, at least one unique uterine protein appeared to be a sub-unit of a larger molecule.

Oestradiol induced changes of soluble protein synthesis in human endometrium

The effect of an in vitro application of oestradiol-17-beta on the soluble protein synthesis in human endometrium during the menstrual cycle was investigated. Results obtained by double-label technique and SDS-polyacrylamide gel or Cellogel electrophoresis show that synthesis of soluble proteins in human endometrium is affected by oestradiol in both follicular and luteal phases of the cycle. One of the proteins obtained after oestradiol treatment seems to be similar to IP of rat uterus as judged from its molecular weight (41,000 daltons) and electrophoretic mobility (RF:1.18-1.24 relative to BSA on Cellogel). The magnitude of this protein synthesis correlates significantly with cytoplasmic oestradiol receptor concentration in endometrium throughout the cycle. The highest induction of IP like protein(s) synthesis at follicular phase and a decreased induction during the luteal phase was detected. No quantitative relationship between the changes of progesterone receptor concentration and IP like protein synthesis was found.

Differential clinical response to oestrogens after menopause

An analysis of vasomotor, psychological, and physical symptoms of 136 women who were receiving piperazine oestrone sulphate (Ogen) and conjugated equine oestrogens (Premarin) after menopause has shown differences in responses which can be explained only if it is accepted that the two oestrogenic compounds have differing effects on various parts of the body. Premarin (0.625 mg) was found to be more potent at inducing withdrawal bleeding than Ogen (1.25 mg), whereas Ogen was more effective than Premarin in alleviating hot flushes and some psychological symptoms. A hypothesis involving metabolism of oestrone to the catecholamine, 2-hydroxyoestrone, is postulated, which explains why these differences occur. It is further suggested that better selection of oestrogens to suit particular postmenopausal symptoms should be encouraged when prescribing oestrogen for women after menopause.

Steroid-induced proteins in human endometrium

The synthesis of soluble proteins in human endometria at various phases of menstrual cycle was evaluated by polyacrylamide gel electrophoresis of [35S]methionine-labeled proteins. Densitometric analysis of the gels revealed alterations in the rate of synthesis of single protein bands throughout the cycle. Administration of conjugated estrogens (Premarin) to women undergoing hysterectomy, or exposure, in vitro, of the endometrial tissue to 17 beta-estradiol produced an increased incorporation of [35S]methionine into a specific protein which migrated on SDS-polyacrylamide gels at a molecular weight of about 55 000. Induction of this protein was observed only in those endometria showing a secretory histological appearance. The protein was resolved into at least 2 different spots in two-dimensional gel electrophoresis. An increase in the rate of synthesis of another endometrial protein with an apparent molecular weight of 51 000 was observed in tissues exposed in vitro to medroxyprogesterone acetate. These steroid-induced proteins may be a useful marker for studying hormone action in both normal and neoplastic endometria.

A comparative study of nucleic acid content and electrophoretic analysis of human decidual and endometrial proteins

DNA, RNA and protein content expressed in terms of tissue wet weight was significantly reduced in decidua compared to endometrium. A protein with an approximate molecular weight of 36 000 was detected in higher incidence in decidua compared to normal endometrium. Another protein with a molecular weight of 26 000 was detected predominantly in decidua and secretory endometrium. Semiquantitative changes were also observed in the decidua. The peak area of one protein with a molecular weight of 48 000, which was significantly elevated in the secretory compared to the proliferative phase of the cycle, was significantly reduced in early pregnancy decidua. However, in term decidua the peak area of this protein was similar to those in endometrial tissue obtained in the luteal phase of the menstrual cycle. The results demonstrated that the transformation of endometrial stromal cells to decidua involves changes in nucleic acid and protein profiles and is accompanied by enhanced synthesis of at least one protein.

Progestogen-dependent endometrial protein in women: tissue concentration in relation to developmental stage and to serum hormone levels

The presence of a progestogen-dependent endometrial protein (PEP) in women was previously described. The present study was undertaken to determine whether the occurrence or the concentration of PEP in endometria is related to the developmental stage of tissues and/or to the levels of endogenous progesterone (P) or 17 beta-estradiol (E) to which the tissues are exposed. Samples of serum and endometrial tissue in different developmental stages were obtained from pregnant women and women with normal menstrual cycles and were analyzed for PEP. In addition, the sera were analyzed for P and E. The occurrence of PEP in the endometrium of all of the women who were studied was found to be correlated with the heightened secretory activity and with the decidual change in the tissue. Furthermore, in women with normal cycles, the detection of PEP was associated with high serum levels of P. Comparison of serum levels of P with endometrial levels of PEP in pregnant women and in women in the mid-secretory phase of the menstrual cycle indicated that a 2.8-fold rise in serum levels of P during pregnancy was accompanied by a comparable (about threefold) rise in tissue levels of PEP. Therefore, we conclude that, in pregnant women and women with normal cycles, the levels of PEP in the endometrium reflect developmental changes within the endometrium, and that those levels are directly related to serum levels of P.

Progesterone-induced glycogen accumulation in human endometrium during organ culture

An organ culture system was used to evaluate the response of human proliferative endometrium to progesterone stimulation. The glycogen content of proliferative tissue was increased as much as thirteenfold during organ culture in media containing progesterone. The steroid-induced increase in tissue glycogen was detectable after 16 hours and reached a maximum at 48 and 72 hours of culture. Progesterone induced a significant increase in glycogen at a media concentration of 1.6 x 10(-8)M and a maximal increase at 3.2 x 10(-7) to 3.2 x 10(-6)M. At higher media concentrations of progesterone (1.6 x 10(-5)M), glycogen levels failed to reach the maximum obtainable. The extent of the response correlated poorly with the initial glycogen content of the tissue and not at all with the initial content of high-affinity progesterone-binding sites in cytosol. Addition of estradiol-17 beta to medium (10(-10)M to 10(-7)) has no effect on the progesterone-induced increase in tissue glycogen. Delaying the addition of progesterone to the cultures for 24 hours resulted in a diminished glycogen response; the reduced response may be related to a rapid decrease in high-affinity progesterone-binding sites as measured in cytosol prepared from tissues cultured in the absence of progesterone. High-affinity progesterone-binding sites in endometrial cytosol were found to decrease rapidly during the first 24 hours of culture. The addition of cycloheximide or actinomycin D to the culture media inhibited the increase in tissue glycogen caused by progesterone. These results demonstrate that progesterone can induce an in vitro response in human proliferative endometrium similar to that seen in vivo. The response of the endometrium is reproducible and allows for comparisons between grouped data obtained by using tissues from several different donors.