Estrogen induced peroxidase secretion from the endometrial epithelium: a possible function for the luminal enzyme.

Estrogen induced peroxidase (EIP) activity revealed as a diaminobenzidine-H2O2 product in electron micrographs is apparent within cisternae of the RER and in large dilated apical vesicles, of which only a few have been seen to open into the uterine lumen. EIP activity is infrequently present in the trans cisternae of the rather diminutive Golgi complex in uterine epithelial cells from 12-72 h after treatment with estrogen. EIP activity is, however, prominent on the surface of microvilli of epithelial cells and as deposits in the lumen. Desalted uterine fluid (72 h) isolated by rotofor (Biorad) and analysed on isoelectric focusing gels that were stained with the diaminobenzidine-H2O2 reaction, reveal the existence of at least 6 peroxidase isoelectric variants with isoelectric points between pI 3.5 and pI 5.0. In similar preparations doubly-stained by diaminobenzidine-H2O2 and silver, peroxidase positive bands are enhanced, along with other isoelectric variants in the acidic pI range. In SDS-PAGE preparations, five prominent proteins ranging from 29-115 kD are present in 72 h uterine fluid. Luminal EIP coats the surface microvilli of the reproductive tract cells, and of viable spermatozoa incubated in uterine fluid. Peroxidase coated bacteria appear to be in the process of decay, and enzyme activity is present on the surface of most spermatozoa. It is not yet determined if EIP has bactericidal, spermicidal or capacitation functions.

Protooncogene, growth factor, growth factor receptor, and estrogen and progesterone receptor gene expression in the immature rat uterus after treatment with estrogen and tamoxifen.

The mechanism(s) by which estrogen regulates cell growth in target cells and the cascade of biochemical changes associated with growth have not yet been fully determined. Equally undetermined is an understanding of the mechanism(s) by which tamoxifen blocks estrogen-regulated growth. This study, therefore, attempts to define and correlate the physiological processes in the rat uterus following estrogen and tamoxifen administration with temporal events manifested by mRNA expression of protooncogenes (m-myc, c-ras, c-fos, c-jun), growth factors and/or inhibins (IGF-1, IGF-2, IGF-2 Exon 1 and Exon 2), EGF, TGFB-1, -2, -3), growth factor or inhibin receptors (EGFr, TGFB-2r, TGFB-3r), and estrogen-induced differentiative proteins including estrogen receptor (ER), progesterone receptor (PR). In this study, mRNA was isolated from hormone and antagonist-treated rat uteri at 0', 15', 30', 1 h, 6 h, 24 h, 48 h and 72 h. Expression studies were analysed by dot/Northern blot hybridization with cDNA or oligonucleotide probes for the RNAs mentioned above. Nuclear runoff transcriptional assays were also performed. Our data suggest that fos, myc, ras and jun protooncogenes were expressed from 15' to 48 h after treatment with either estrogen or tamoxifen. Tamoxifen treatment resulted in diminished expression, but incomplete inhibition of the protooncogene mRNAs. Estrogen treatment resulted in rapid elevation of both EGF and EGFr mRNA levels, both of which were suppressed after tamoxifen treatment. Tamoxifen may exert its antiestrogenic effects by inhibiting EGF and EGFr, and myc protooncogene activity on the one hand, and by overexpression of the TGFB isotypes and their receptors on the other hand. With the proliferation cycle short circuited, tamoxifen-treated cells hypertrophied and differentiated to terminal cells by 24-48 h. Working hypotheses for the mechanisms of action of estrogen and tamoxifen are presented based on our data.