Preclinical profile of BYON3521 predicts an effective and safe c-MET-antibody-drug conjugate

c-MET, the cell-surface receptor for the hepatocyte growth factor/scatter factor (HGF/SF), which is widely overexpressed in various solid cancer types, is an attractive target for the development of antibody-based therapeutics. BYON3521 is a novel site-specifically conjugated duocarmycin-based ADC, comprising a humanized cysteine-engineered IgG1 monoclonal antibody with low pM binding affinity towards both human and cynomolgus c-MET. In vitro studies showed that BYON3521 internalizes efficiently upon c-MET binding and induces both target- and bystander-mediated cell killing. BYON3521 showed good potency and full efficacy in MET-amplified and high c-MET-expressing cancer cell lines; in moderate and low c-MET-expressing cancer cell lines good potencies and partial efficacy were observed. In mouse xenograft models, BYON3521 showed significant anti-tumor activity upon single dose administration in multiple non-MET-amplified tumor types with low, moderate and high c-Met expression, including complete tumor remissions in models with moderate c-MET expression. In the repeat-dose GLP safety assessment in cynomolgus monkeys, BYON3521 was well tolerated and based on the observed toxicities and their reversibility, the highest non-severely toxic dose (HNSTD) was set at 15 mg/kg. A human pharmacokinetics (PK) model was derived from the PK data from the cynomolgus safety assessments, and the minimal efficacious dose in humans is estimated to be in the range of 3-4 mg/kg. In all, our nonclinical data suggests that BYON3521 is a safe ADC with potential for clinical benefit in patients. A first-in-human dose escalation study is currently ongoing to determine the maximum tolerated dose and recommended dose for expansion (NCT05323045).

A Platform for the Generation of Site-Specific Antibody-Drug Conjugates That Allows for Selective Reduction of Engineered Cysteines

Engineering cysteines at specific sites in antibodies to create well-defined ADCs for the treatment of cancer is a promising approach to increase the therapeutic index and helps to streamline the manufacturing process. Here, we report the development of an in silico screening procedure to select for optimal sites in an antibody to which a hydrophobic linker-drug can be conjugated. Sites were identified inside the cavity that is naturally present in the Fab part of the antibody. Conjugating a linker-drug to these sites demonstrated the ability of the antibody to shield the hydrophobic character of the linker-drug while resulting ADCs maintained their cytotoxic potency in vitro. Comparison of site-specific ADCs versus randomly conjugated ADCs in an in vivo xenograft model revealed improved efficacy and exposure. We also report a selective reducing agent that is able to reduce the engineered cysteines while leaving the interchain disulfides in the oxidized state. This enables us to manufacture site-specific ADCs without introducing impurities associated with the conventional reduction/oxidation procedure for site-specific conjugation.

An objective and automated method for evaluating abdominal hyperalgesia in a rat model for endometriosis

Chronic pain and subfertility are the main symptoms of concern in women with endometriosis. In order to find new therapeutic options to suppress the pain, translational animal models are indispensable. We have developed a new automated, experimental setup, with full consideration for animal wellbeing, to determine whether operant behaviour can reveal abdominal hyperalgesia in rats with surgically-induced endometriosis, in order to assess whether abdominal hyperalgesia affect behavioural parameters. Endometriosis was induced by transplantation of uterine fragments in the abdominal cavity. Control groups consisted of sham-operated rats and non-operated rats. We have developed an operant chamber (Skinnerbox) which includes a barrier. The rat can climb the barrier in order to reach the food pellet, increasing in this way the pressure to the abdomen. We show that endometriosis rats collect significantly less sugar pellets when compared with the control rats after the introduction of the barrier. In the Skinnerbox experiment, we showed that in a positive operant setting, the introduction of a barrier results in a contrast of operant behaviour of endometriosis rats and control groups, perchance as a result of abdominal discomfort/hyperalgesia due to surgically-induced endometriosis. This is a promising start for the further development of a refined animal model to monitor abdominal discomfort/hyperalgesia in rats with surgically-induced endometriosis.

The Preclinical Profile of the Duocarmycin-Based HER2-Targeting ADC SYD985 Predicts for Clinical Benefit in Low HER2-Expressing Breast Cancers

SYD985 is a HER2-targeting antibody-drug conjugate (ADC) based on trastuzumab and vc-seco-DUBA, a cleavable linker-duocarmycin payload. To evaluate the therapeutic potential of this new ADC, mechanistic in vitro studies and in vivo patient-derived xenograft (PDX) studies were conducted to compare SYD985 head-to-head with T-DM1 (Kadcyla), another trastuzumab-based ADC. SYD985 and T-DM1 had similar binding affinities to HER2 and showed similar internalization. In vitro cytotoxicity assays showed similar potencies and efficacies in HER2 3+ cell lines, but in cell lines with low HER2 expression, SYD985 was 3- to 50-fold more potent than T-DM1. In contrast with T-DM1, SYD985 efficiently induced bystander killing in vitro in HER2-negative (HER2 0) cells mixed with HER2 3+, 2+, or 1+ cell lines. At pH conditions relevant for tumors, cathepsin-B cleavage studies showed efficient release of the active toxin by SYD985 but not by T-DM1. These in vitro data suggest that SYD985 might be a more potent ADC in HER2-expressing tumors in vivo, especially in low HER2-expressing and/or in heterogeneous tumors. In line with this, in vivo antitumor studies in breast cancer PDX models showed that SYD985 is very active in HER2 3+, 2+, and 1+ models, whereas T-DM1 only showed significant antitumor activity in HER2 3+ breast cancer PDX models. These properties of SYD985 may enable expansion of the target population to patients who have low HER2-expressing breast cancer, a patient population with still unmet high medical need.

Intestinal tumorigenesis is not affected by progesterone signaling in rodent models

Clinical data suggest that progestins have chemopreventive properties in the development of colorectal cancer. We set out to examine a potential protective effect of progestins and progesterone signaling on colon cancer development. In normal and neoplastic intestinal tissue, we found that the progesterone receptor (PR) is not expressed. Expression was confined to sporadic mesenchymal cells. To analyze the influence of systemic progesterone receptor signaling, we crossed mice that lacked the progesterone receptor (PRKO) to the Apc^Min/+ mouse, a model for spontaneous intestinal polyposis. PRKO-Apc^Min/+mice exhibited no change in polyp number, size or localization compared to Apc^Min/+. To examine effects of progestins on the intestinal epithelium that are independent of the PR, we treated mice with MPA. We found no effects of either progesterone or MPA on gross intestinal morphology or epithelial proliferation. Also, in rats treated with MPA, injection with the carcinogen azoxymethane did not result in a difference in the number or size of aberrant crypt foci, a surrogate end-point for adenoma development. We conclude that expression of the progesterone receptor is limited to cells in the intestinal mesenchyme. We did not observe any effect of progesterone receptor signaling or of progestin treatment in rodent models of intestinal tumorigenesis.

Role and regulation of the serum- and glucocorticoid-regulated kinase 1 in fertile and infertile human endometrium

Using cDNA microarray analysis, we identified SGK1 (serum- and glucocorticoid-regulated kinase 1) as a gene aberrantly expressed in midsecretory endometrium of women with unexplained infertility. SGK1 is a serine/threonine kinase involved primarily in epithelial ion transport and cell survival responses. Real-time quantitative PCR analysis of a larger, independent sample set timed to coincide with the period of uterine receptivity confirmed increased expression of SGK1 transcripts in infertile women compared with fertile controls. We further demonstrate that SGK1 expression is regulated by progesterone in human endometrium in vivo as well as in explant cultures. During the midsecretory phase of the cycle, SGK1 mRNA and protein were predominantly but not exclusively expressed in the luminal epithelium, and expression in this cellular compartment was higher in infertile women. In the stromal compartment, SGK1 expression was largely confined to decidualizing cells adjacent to the luminal epithelium. In primary culture, SGK1 was induced and phosphorylated upon decidualization of endometrial stromal cells in response to 8-bromo-cAMP and progestin treatment. Moreover, overexpression of SGK1 in decidualizing cells enhanced phosphorylation and cytoplasmic translocation of the forkhead transcription factor FOXO1 and inhibited the expression of PRL, a major decidual marker gene. Conversely, knockdown of endogenous SGK1 by small interfering RNA increased nuclear FOXO1 levels and enhanced PRL expression. The observation that SGK1 targets FOXO1 in differentiating human endometrium, together with its distinct temporal and spatial expression pattern and increased expression in infertile patients, suggest a major role for this kinase in early pregnancy events.

Transforming growth factor beta1 gene polymorphism 509C/T in deep infiltrating endometriosis

Deep infiltrating endometriosis is characterized by the presence of nodular lesions largely composed of fibromuscular tissue. Transforming growth factor beta 1 (TGF-beta1) is the cytokine most causatively associated with disorders characterized by fibrosis throughout the body. Therefore, the hypothesis was tested that mechanisms increasing the fraction of biologically active TGF-beta1, such as TGF-beta 1 gene polymorphisms, lead to an increased risk of developing deep infiltrating endometriosis. The frequency of the -509C/T polymorphism of the TGF-beta 1 gene was tested in women with deep infiltrating endometriosis (n = 72), gynecological patients without symptoms of endometriosis (n = 95) and healthy females (n = 93). Detection of the -509C/T polymorphisms was performed using PCR-restriction fragment length polymorphism analysis. We did not observe statistically significant differences in the frequency of the -509C/T polymorphism between the groups. Our study does not support an association between the -509C/T polymorphism of the TGF-beta 1 gene and an increased risk of deep infiltrating endometriosis.

Estrogen and the endometrium: lessons learned from gene expression profiling in rodents and human

To date, research into the biological processes and molecular mechanisms associated with endometrial receptivity and embryo implantation has been a focus of attention, whereas the complex events that occur in the human endometrium during the menstrual and proliferative phase under the influence of estrogen have received little attention. The objective of this review is to provide an update of our current understanding of the actions of estrogen on both human and rodent endometrium, with special emphasis on the regulation of uterine growth and cell proliferation, and the value of global gene expression analysis, in increasing understanding of these processes.

Hypoxia contributes to development of recurrent endometrial carcinoma

Tumor hypoxia can trigger the induction of angiogenesis. High microvessel density (MVD) as well as hypoxia-inducible factor-1alpha (HIF-1alpha) have been related to recurrent disease and tumor aggressiveness, respectively. In this study, MVD and hypoxic status were investigated in primary and recurrent endometrial carcinomas. A total of 65 primary tumors of patients with recurrent endometrial carcinoma (n = 40), and without recurrent endometrial carcinoma (n = 25) were studied. Immunohistochemical analysis was performed on paraffin-embedded tumor tissue. MVD was determined by quantitative analysis of CD31/FVIII positive vessels. Tumor hypoxia was estimated by evaluating the expression of the hypoxia-regulated gene HIF-1alphaand its target gene carbonic anhydrase IX (CA-IX). An additional 23 recurrent tumors were available for determination of MVD and HIF-1alpha expression. Effects of hypoxia on tumor protein p53 (TP53) expression were evaluated in the endometrial cancer cell lines (ECC-1), Ishikawa (derived from adenocarcinomas), and AN3CA (derived from a lymph node metastasis). MVD, CA-IX, and HIF-1alpha expression were not significantly different in primary tumors of patients with recurrence compared to the control tumors. The MVD was significantly lower, and HIF-1alpha expression was significantly higher in recurrent tumors when compared with their primary tumors (paired t test, P < 0.05). HIF-1alpha expression correlated well with TP53 expression levels in primary tumors, but not in recurrences. TP53 protein levels were highest in AN3CA cells. Hypoxic conditions induced TP53 protein in ECC-1 and Ishikawa, but not AN3CA cells. We conclude that MVD, CA-IX, and HIF-1alpha expression are not independent prognostic markers for recurrent endometrial carcinoma. The low MVD, increased HIF-1alpha protein levels, dissociation of hypoxia, and TP53 protein induction in the metastatic tumor cells (AN3CA) support a role for hypoxia in the development of recurrent endometrial carcinoma.

RASSF1A methylation and K-ras and B-raf mutations and recurrent endometrial cancer

BACKGROUND

Aberrations in mediators of Ras signaling may increase the risk of developing recurrent endometrial carcinoma.

PATIENTS AND METHODS

Primary tumors of patients with (n = 44) and without (n = 44) recurrent stage I endometrioid endometrial carcinoma were compared regarding the presence of K-ras mutations (codons 12 and 13), B-raf mutations (V599), and RASSF1A gene promoter methylation.

RESULTS

K-ras mutations were present in 18% of the patients independent of recurrent disease. No B-raf mutations were found. RASSF1A methylation was demonstrated in 85% of endometrial carcinomas, independent of recurrence. The presence of K-ras mutations and RASSF1A promoter methylation were not related, either directly or inversely. Analysis in premenopausal endometrial carcinomas demonstrated K-ras mutations in 40%, no B-raf mutations, and RASSF1A promoter methylation in 70% of the cases. RASSF1A methylation was also observed in samples of cyclic (n = 14), hyperplastic (n = 8), and atrophic (n = 13) endometrial tissues in 21%, 50% and 38%, respectively.

CONCLUSIONS

RASSF1A methylation was observed in a high frequency in endometrioid endometrial carcinoma whereas K-ras and B-raf mutations were observed in a low frequency. No association was observed with the development of recurrent disease. High-frequency RASSF1A methylation in premenopausal carcinomas and an increased frequency in endometrial hyperplasia indicate that this may be an early event in endometrial carcinogenesis.

Progesterone receptor polymorphism +331G/A is associated with a decreased risk of deep infiltrating endometriosis

BACKGROUND

Alterations in the progesterone receptor (PR) are considered a risk factor for the development of endometriosis. In this study, the frequencies of the PROGINS and +331G/A polymorphisms of the PR gene were determined in deep infiltrating endometriosis and correlated with the expression of the PR protein.

METHODS AND RESULTS

The frequencies of the PR polymorphisms were determined in women with deep infiltrating endometriosis (n = 72), women with adenomyosis in the uterine wall (n = 40), gynaecological patients without symptomatic endometriosis (n = 102) and healthy females (n = 93). Detection of +331G/A and PROGINS polymorphisms was performed using PCR-restriction fragment length polymorphism (RFLP) analysis. Expression of PR-A and PR-B protein was assessed with immunohistochemistry. The allelic frequency of the polymorphic allele +331A was lower in women with endometriosis (P < 0.01) and adenomyosis (P < 0.02) compared with healthy females. The frequency of the PROGINS polymorphism did not differ between the groups. The mean staining index (SI) for PR-B in endometriotic epithelium was higher in the presence of the +331A polymorphic allele (n = 2) (P < 0.001) compared with +331G/G individuals (n = 61). The PROGINS polymorphism did not affect the SI for PR-A and PR-B.

CONCLUSIONS

The presence of the PR gene polymorphic allele +331A is associated with a reduced risk of deep infiltrating endometriosis and adenomyosis compared with healthy population controls. The PROGINS polymorphism does not seem to modify the risk of deep infiltrating endometriosis.

Tibolone and metabolites induce prolactin production in human endometrial stromal cells in vitro: evidence for cell-specific metabolism

In this study, we assessed the effects of tibolone and its metabolites on the production of a progesterone sensitive parameter, prolactin, in human endometrium stroma cells in vitro. In addition, the metabolism of the compounds by isolated stromal and epithelial cells was evaluated. The reference compounds, progesterone, Org 2058, and DHT all induced prolactin production. Oestradiol also slightly induced prolactin production and enhanced the response to Org 2058. Tibolone and Delta4-tibolone were similar with regard to potency to induce prolactin levels in the culture supernatant. Their potency was lower than that of Org 2058, similar to that of progesterone and higher than that of DHT. The efficacies of tibolone, Delta4-tibolone and Org 2058 were similar (approximately 200-fold induction). The estrogenic tibolone metabolites 3alpha- and 3beta-OH tibolone also significantly stimulated prolactin production. Their potency, however, was low since significance was reached only at the highest concentrations tested. The PR antagonist Org 31710 inhibited both tibolone- and Delta4-tibolone-induced prolactin production. The responses of tibolone and Delta4-tibolone were not affected by co-incubation with the androgen receptor antagonist OH-flutamide. The effect of tibolone, but not Delta4-tibolone, was antagonized approximately 50% in combination with the highest dose (1 microM) estrogen receptor antagonist, ICI 164384. The induction of prolactin by 3alpha- and 3beta-OH tibolone was antagonized most potently by Org 31710, but also by ICI 164384 and OH-flutamide. Tibolone is metabolized differently in epithelial and stromal cells of the human endometrium. The epithelial cells mostly produce the progestagenic/androgenic Delta4-tibolone. The stromal cells produce predominantly the 3beta-OH tibolone, and some Delta4-tibolone, but the net effect observed with regard to prolactin production is progestagenic. When the metabolites 3alpha-OH, 3beta-OH, and Delta4-tibolone were added to the cultures no conversions were observed. The HPLC analyses showed no evidence for the production of sulfated metabolites. In conclusion, the net effects on endometrial stromal cells are predominantly progestagenic. Tibolone is converted by epithelial cells into Delta4-tibolone which displays progestagenic and androgenic activities, whereas in stromal cells also the estrogenic metabolites 3alpha- and 3beta-OH tibolone are formed.

Expression and regulation of vascular endothelial growth factor ligands and receptors during menstruation and post-menstrual repair of human endometrium

Regeneration and growth of the human endometrium after shedding of the functional layer during menstruation depends on an adequate angiogenic response. We analysed the mRNA expression levels of all known vascular endothelial growth factor (VEGF) ligands and receptors in human endometrium collected in the menstrual and proliferative phases of the menstrual cycle. In addition, we evaluated the expression of VEGF-A, VEGF-R2 and NRP-1 at the protein level. Two periods of elevated mRNA expression of ligands and receptors were observed, separated by a distinct drop at cycle days (CDs) 9 and 10. Immunohistochemical staining showed that VEGF and VEGF-R2 were expressed in epithelial, stromal and endothelial cells. NRP-1 was mainly confined to stroma and blood vessels; only in late-proliferative endometrium, epithelial staining was also observed. Except for endothelial VEGF-R2 expression in CDs 6-8, there were no significant differences in the expression of VEGF, VEGF-R2 or NRP-1 in any of the cell compartments. In contrast, VEGF release by cultured human endometrium explants decreased during the proliferative phase. This output was significantly reduced in menstrual and early-proliferative endometrium by estradiol (E2) treatment. Western blot analysis indicated that part of the VEGF-A was trapped in the extracellular matrix (ECM). Changes in VEGF ligands and receptors were associated with elevated expression of the hypoxia markers HIF1alpha and CA-IX in the menstrual and early proliferative phases. HIF1alpha was also detected in late-proliferative phase endometrium. Our findings indicate that VEGF-A exerts its actions mostly during the first half of the proliferative phase. Furthermore, VEGF-A production appears to be triggered by hypoxia in the menstrual phase and subsequently suppressed by estrogen during the late proliferative phase.

TP53 overexpression in recurrent endometrial carcinoma

OBJECTIVE

To study alterations within the p53 pathway in relation to the development of recurrent stage I endometrioid endometrial carcinoma.

METHODS

Paraffin-embedded tumor tissue of both primary and recurrent tumors from 44 patients with and 44 without recurrence was used for immunohistochemical analysis of TP53, hMdm2, P21(Waf1/Cip1) and M30. DNA was extracted, and mutation analysis of p53 (exon 5-8, 11) was performed by direct sequencing.

RESULTS

TP53 overexpression was significantly associated with recurrent disease: Odds Ratio 3.8 (95% CI: 1.5-9.8). Overexpression of TP53 was associated with lower staining indices (SI:0-9) of both hMdm2 and P21 in tumors of patients with recurrence, compared to controls: 2.0 +/- 0.4 vs. 4.0 +/- 0.8 and 1.9 +/- 0.8 vs. 3.6 +/- 0.8, respectively. Eight p53 missense mutations were identified in six patients with recurrence and two controls. One nonsense mutation was found in a patient with recurrence and one deletion in a control patient. Only a minority of TP53 overexpression cases could be explained by the presence of these p53 mutations.

CONCLUSION

TP53 overexpression was significantly predictive for recurrent endometrial carcinoma, and mostly not correlated with p53 mutations. Concomitant low hMdm2 and P21(Waf1/Cip1) expression in tumors with overexpressed TP53 suggests a dysfunctional TP53-P21(Waf1/Cip1) pathway.

Molecular characterization of soluble factors from human menstrual effluent that induce epithelial to mesenchymal transitions in mesothelial cells

We have studied menstrual effluent in order to identify soluble menstrual factors that induce epithelial to mesenchymal transitions (EMT) in mesothelial cells. A variety of molecules, such as nitric oxide and its reaction products, proteases (i.e. matrix metalloproteinases, plasmin) and proteins and/or peptides (i.e. growth factors: b-fibroblast growth factor, epidermal growth factor, hepatocyte growth factor, transforming growth factor-beta; cytokines: interleukin 1 beta, tumour necrosis factor-alpha [TNF-alpha]) may be involved in this process. We have demonstrated that TNF-alpha is involved in EMT, whereas the other molecules are not. Biochemical analysis has shown that the inducing menstrual factors are heat-labile molecules, are uncharged at neutral pH, have a molecular weight between 50-70 kDa (or are bound in complexes of that size) and are eluted in the albumin fraction during gel filtration chromatography. Further analysis of this fraction by using proteomics and mass spectrometry has led to the identification of alpha-enolase and haemoglobin whose inhibition partially prevents EMT. When antibodies against TNF-alpha, alpha-enolase and haemoglobin are combined, EMT is almost completely inhibited. Thus, the candidates for soluble menstrual factors that induce mesothelial EMT are TNF-alpha, alpha-enolase and haemoglobin.

Vascular development in endometriosis

Endometriosis, defined as the presence of endometrial tissue outside the uterus, is an estrogen-dependent disease which causes pelvic pain and subfertility in women of reproductive age. The condition has a dramatic impact on the professional, social and marital life of sufferers. Direct and indirect evidence suggests that angiogenesis is required for the development and persistence of endometriosis. In this review the state-of-the-art with regard to our understanding of the role of angiogenesis in the ectopic implantation and survival of menstrual endometrial tissue will be discussed.

Proteome analysis of human mesothelial cells during epithelial to mesenchymal transitions induced by shed menstrual effluent

Peritoneal endometriosis is the result of ectopic implantation and growth of endometrium tissue that has been regurgitated into the abdominal cavity during menstruation. We have previously shown that menstrual effluent induces epithelial to mesenchymal transitions (EMT) in mesothelial cells, which results in cell retraction and exposure of submesothelial extracellular matrix. Since endometrial tissue preferentially adheres to the extracellular matrix, adhesion of endometrial tissue to the peritoneum is facilitated. The EMT were shown to be associated with differential expression and phosphorylation of mesothelial proteins. Using radiolabeling and proteomics we detected changes in protein expression and phosphorylation that occur in mesothelial cells during the EMT process. The identity of 73 proteins, which were obtained from 324 analyzed spots, was confirmed. The expression of 35 proteins involved in organization of the cytoskeleton, signal transduction, regulation of the redox state, and production of ATP, was altered during the EMT process. Four of the identified proteins were differentially phosphorylated: annexin-1, an actin-binding protein and a substrate for receptor tyrosine kinases; tropomyosin-alpha, a regulator of actin filament stability and cell shape; elongation factor 1 delta; ATP synthase beta-chain. In conclusion, factors from menstrual effluent induce specific changes in the expression and phosphorylation status of structural, regulatory and metabolic proteins relevant to the complex process of EMT in mesothelial cells.

Angiostatic agents prevent the development of endometriosis-like lesions in the chicken chorioallantoic membrane

A prospective study was performed to determine the effects of the angiostatic compounds anti-hVEGF antibody, TNP-470, endostatin, and anginex on the vascularization and on endometriosis-like lesion formation in the chicken chorioallantoic membrane model. Endometriosis-like lesion formation was significantly impaired after treatment with angiostatic agents, which was associated with decreased vessel densities in the surrounding chorioallantoic membrane and more necrosis in the endometriosis-like lesions.

Aberrations in the progesterone receptor gene and the risk of recurrent endometrial carcinoma

A case-control study was performed in order to determine whether expression of the progesterone receptor (PR) and/or aberrations of the PR gene contribute to the development of recurrent endometrial carcinoma. Primary tumours from 44 patients with recurrence of stage I endometrial carcinoma (patients) within 3 years after initial treatment were compared with tumours from 44 matched patients who were free of recurrence for a minimum of 3 years (controls). Paraffin wax-embedded primary tumours (n = 88) and recurrent tumours (n = 32) were analysed immunohistochemically for PR expression. A staining index (SI = 0-9) based on the staining intensity and the number of stained cells was calculated. DNA extracted from paraffin wax-embedded tissues was subjected to PCR-restriction fragment length polymorphism analysis (PCR-RFLP) for determination of the PROGINS DNA sequence alterations and the +331G/A-promoter polymorphism. Low PR expression (SI < 1.0) was observed in 7% of primary tumours derived from controls, 25% of primary tumours from patients with recurrence, and 38% of recurrent tumours. The expression of PR was significantly lower in primary tumours from patients with recurrence (SI = 4.0 +/- 0.5) than in the tumours in the control group (SI = 5.6 +/- 0.5) (T-test for paired analysis, p < 0.05). The PROGINS and +331G/A-promoter polymorphism were not related to age at diagnosis, tumour grade or myometrial invasion. The +331G/A-promoter polymorphism was present in 14% of primary tumours from patients without recurrence, compared with 17% of patients with recurrence. The PROGINS polymorphism was observed in 16% of primary tumours from patients without, and in 34% of patients with, recurrence (OR 2.6; 95% CI: 0.9-7.6). Most interestingly, patients who carried the PROGINS variant and in whom a PR-expressing tumour was diagnosed were at significantly enhanced risk of relapse (OR 4.7; 95% CI: 1.3-17.1). In conclusion, low PR expression tended to be associated with recurrent disease, and PR expression in tumours from patients carrying the PROGINS allele was predictive of the risk of recurrence.

APC, beta-catenin, and E-cadherin and the development of recurrent endometrial carcinoma

Endometrial carcinoma, generally, has a good prognosis. However, in some patients, the tumor appears to behave very aggressively, a course that cannot be explained with histopathological characteristics. More insight into the molecular background can be valuable to clarify these differences in tumor behavior. The three components associated with the Wnt pathway--i.e., adenomatous polyposis coli (APC), beta-catenin, and E-cadherin--were evaluated in a case-control study of 28 patients with stage-I endometrial carcinomas to determine their involvement in the development of recurrent disease. Mutation analysis of the mutation cluster region of the APC gene, determination of gene promoter methylation status of the APC-1A and E-cadherin genes, and immunohistochemical analysis of APC, E-cadherin, and beta-catenin were performed using paraffin-embedded tumor tissue. Twenty-one APC gene mutations were detected in 12 of 28 (43%) patients. Only three mutations would result in a stopcodon in the APC gene. APC gene promoter methylation was assessed in 12 of 28 (43%) patients. APC immunostaining was absent in two of 24 (8.3%) patients. The occurrence of APC mutations, APC gene promoter methylation, and APC immunostaining were not predictive for recurrence. No E-cadherin expression was observed in four of 24 patients (17%). E-cadherin gene promoter methylation could not be detected in any of the patients. The absence of E-cadherin expression was predictive for distant metastases, but not for local recurrence. Nuclear localization of beta-catenin was present in nine of 24 (38%) patients and was not predictive for recurrent disease. Involvement of epigenetic and genetic aberrations in APC and beta-catenin genes seems to be of minor importance for the development of local recurrences and distant metastases. Although the number of patients is limited, E-cadherin expression appears to be predictive for the development of distant metastases in endometrial carcinoma.

Menstrual effluent induces epithelial-mesenchymal transitions in mesothelial cells

BACKGROUND

Menstrual effluent affects mesothelial cell (MC) morphology. We evaluated whether these changes were consistent with epithelial-mesenchymal transitions (EMT).

METHODS

Monolayer cultures of MC were incubated overnight in conditioned media, prepared from cells isolated form menstrual effluent, with or without kinase and ATP inhibitors. Changes in cell morphology were monitored using time-lapse video microscopy and immunohistochemistry. Effects on the expression of EMT-associated molecules were evaluated using real-time RT-PCR and/or Western blot analysis.

RESULTS

Incubation in conditioned media disrupted cell-cell contacts, and increased MC motility. The changes were reversible. During the changes the distribution of cytokeratins, fibrillar actin and alpha-tubulin changed. Sodium azide, an inhibitor of ATP production, and Genistein, a general tyrosine kinase inhibitor, antagonized these effects. Wortmannin, a phosphatidylinositol 3-kinase inhibitor, and SU6656, an Src tyrosine kinase inhibitor, only partially antagonized the effect. The expression of Snail and vimentin was markedly up-regulated, whereas the expression of E-cadherin was decreased and cytokeratins were altered.

CONCLUSIONS

In MC, menstrual effluent initiates a reversible, energy-dependent transition process from an epithelial to a mesenchymal phenotype. Involvement of the (Src) tyrosine kinase signalling pathway and the changes in the expression of cytokeratins, Snail, vimentin and E-cadherin demonstrate that the morphological changes are EMT.

Defective mismatch repair and the development of recurrent endometrial carcinoma

OBJECTIVE

To investigate whether defective DNA mismatch repair (MMR) defines a subgroup at risk for recurrence in sporadic endometrial carcinoma patients.

METHODS

Primary tumors from 44 patients with recurrent stage I endometrial carcinoma were compared after matching, with tumors of 44 patients being free of recurrence for minimal 3 years. Paraffin-embedded primary tumors (n = 88) and recurrent tumors (n = 32) were subjected to immunohistochemical analysis for hMSH2 and hMLH1 expression. Subsequently, a staining index (SI = 0-9) was calculated based on staining intensity and quantity. DNA was extracted from paraffin-embedded tissues, and promoter methylation of hMLH1 was determined by nested methylation-specific PCR (MSP). Microsatellite instability (MSI) was assessed by BAT-26 or BAT-25.

RESULTS

Low hMSH2 expression was observed in 2% of primary tumors of control patients without recurrence, 14% of primary tumors of patients with recurrence, and 0% of recurrent tumors. Low hMLH1 expression was observed in 32%, 19%, and 22%, respectively. hMLH1 gene promoter methylation was detected in 50%, 47%, and 32%, and MSI was found in 16%, 14%, and 30%, respectively. No significant differences were found between primary tumors of patients with and without recurrence with respect to hMSH2 and hMLH1 expression, hMLH1 promoter methylation, and MSI. When primary and recurrent tumors were compared, there was an increased correlation of hMLH1 methylation with low hMLH1 expression and MSI in recurrent tumors.

CONCLUSION

MSI, hMLH1 promoter methylation, and the expression of hMLH1 and hMSH2 are not predictive for the development of recurrent stage I endometrial carcinoma. In the progression of tumor, "de novo" hMLH1 methylation rarely occurs, instead there is further derailment of the MMR pathway in affected tumors.

Inhibiting MMP activity prevents the development of endometriosis in the chicken chorioallantoic membrane model

BACKGROUND

Matrix metalloproteinases (MMPs) are essential for extracellular matrix remodelling and may contribute to the development of endometriosis. Transplantation of endometrium onto the chicken chorioallantoic membrane (CAM) results in endometriosis-like lesion formation, a process that requires extensive tissue remodelling. We investigated the expression of a wide range of MMPs in menstrual endometrium, endometriosis-like lesions in CAMs, in peritoneal endometriosis and in endometriosis in the rectovaginal space, as well as the function of MMPs in early lesion formation in the CAM model.

METHODS

Expression of MMPs was evaluated by immunohistochemistry and MMP function was studied in the CAM by inhibiting MMP activity during lesion formation.

RESULTS

Nearly all MMPs were present in all tissues studied. No significant differences in the expression of a majority of MMPs were found in endometriosis-like lesions in CAMs when compared with human endometriosis. Inhibition of MMP-1, -2, -3, -7 and -13 activities significantly impaired endometriosis-like lesion formation in CAMs.

CONCLUSIONS

The MMP expression profiles of experimentally induced endometriosis in CAMs and human endometriosis are similar. The prevention of endometriosis-like lesion formation in the CAM by inhibiting MMP activity strongly suggests that MMPs have a function in the early development of endometriotic lesions.

Pathogenesis of endometriosis

Many women harbour spots of peritoneal endometriosis without having any symptoms; this is referred to as the phenomenon endometriosis. Some of these women go on to develop symptomatic endometriosis. Although we know the factors potentially involved in the aetiology and pathogenesis of endometriosis, the exact mechanism by which the phenomenon endometriosis develops into the disease endometriosis, with its associated signs and symptoms, remain obscure. The widely accepted theory is Sampson's transplantation theory. Recent findings indicate that certain properties of the endometrium, and the influence of the local environment, are crucial in the development of endometriosis. Early endometriosis lesion formation is described in detail, as this seems to be a key process in the development of peritoneal endometriosis.

Antiangiogenesis therapy for endometriosis

It is known that angiogenesis is of pivotal importance for the development of endometriosis. However, in the treatment of endometriosis patients, prevention of endometriosis lesion development only will not be sufficient as a therapy. Treatment options, aimed at interfering with established lesions, have to be developed. In this study we evaluated whether inhibition of angiogenesis by angiostatic therapy is also effective in antagonizing the sustentation of endometriosis. We evaluated the effect of the angiostatic compounds antihuman vascular endothelial growth factor, TNP-470, endostatin, and anginex on the growth of established endometriosis lesions in the nude mouse model. We show that human endometrium in the proliferative endometrium is highly angiogenic and that vascular endothelial growth factor-A is the most important angiogenesis promotory factor. The angiostatic compounds significantly decreased microvessel densities and the number of established endometriosis lesions. In the remaining lesions, the number of pericyte-protected vessels is not different in control and treated mice; however, the number of unprotected vessels was significantly reduced in the groups treated with the angiostatic agents. Our data demonstrate that inhibitors of angiogenesis effectively interfere with the maintenance and growth of endometriosis by inhibiting angiogenesis. This suggests that the use of angiostatic agents may be promising as a therapy for endometriosis.

Tissue integrity is essential for ectopic implantation of human endometrium in the chicken chorioallantoic membrane

BACKGROUND

Not all women with patent tubes develop clinically manifest endometriosis. Quality and quantity of endometrium in retrograde menstruation may be the determining factor in the development of the disease. We hypothesize that retrograde shedding of endometrial fragments with preserved integrity facilitates implantation of endometrium in ectopic locations, resulting in endometriotic lesion development. We evaluate the impact of tissue integrity on the success of endometriosis-like lesion development in the chicken embryo chorioallantoic membrane (CAM) model.

METHODS

Menstrual and non-menstrual (cyclic) endometrium were collected by biopsy, and either minced or enzymatically dispersed. Spontaneously shed menstrual effluent was collected by a menstrual cup, and cells and tissue were isolated. We evaluated whether infiltration or lesion formation in the CAM occurred after transplantation of endometrium onto the CAM.

RESULTS

Transplantation of biopsied menstrual and cyclic endometrium fragments, and of endometrium fragments >1 mm(3) isolated from menstrual effluent, resulted in lesion formation. Transplantation of endometrial cells isolated from menstrual effluent did not lead to lesion formation. After transplantation of digested biopsied cyclic endometrium, infiltration in the CAM but no lesions were observed.

CONCLUSION

In the CAM assay, integrity of tissue architecture determines success of implantation of human endometrium in ectopic locations.

Retinol and estradiol regulation of retinol binding protein and prostaglandin production by porcine uterine epithelial cells in vitro

Secretion into the uterine lumen follows a precise pattern during early pregnancy. Near the end of the second week of pregnancy and coincident with elongation of conceptuses, retinol, retinol binding protein (RBP), estradiol (E2), and prostaglandins E (PGE) and F (PGF) increase in the uterine lumen, and RBP mRNA increases in the endometrium. In the present studies the potential for E2 (0.1 microM) and retinol (10 microM) to regulate RBP and PG production by cultured luminal (LEC) and glandular (GEC) epithelial cells collected from postpubertal females and LEC from prepubertal gilts was examined. Endometrial tissue was collected surgically from cyclic and pregnant females (n = 8) on d 10 and 13 postestrus (first day of estrus = d 0) and from 120- and 150-d-old prepubertal gilts that were treated with progesterone (P4) (2.2 mg x kg(-1) x d(-1), n = 6) or corn oil (n = 6) for 14 d prior to tissue collection. The LEC from postpubertal females responded to retinol with increased (P < 0.05) RBP, PGE, and PGF in culture medium and increased (P < 0.07) RBP mRNA but E2 decreased (P < 0.05) RBP and RBP mRNA and had no effect on prostaglandins. No E2 or retinol effects on secretions of GEC occurred in vitro, but a day x pregnancy status interaction (P < 0.06) affected PGE output by the GEC. Secretion of PGE was greater when GEC were collected on d 10 of pregnancy than from d-10 cyclic or d-13 pregnant or cyclic females. Both E2 and retinol stimulated (P < 0.05) secretion of RBP by LEC isolated from prepubertal gilts, but their effects were not additive. In vivo treatment of prepubertal gilts with P4 increased (P < 0.05) RBP and decreased (P < 0.05) PG production by LEC in vitro. Therefore responses to E2 and retinol differ between pre- and post-pubertal females, and retinol may function in the regulation of endometrial RBP and PG secretion.

Endometrial angiogenesis throughout the human menstrual cycle

BACKGROUND

The timing and mechanisms of new blood vessel formation in the endometrium during the menstrual cycle are still largely unknown. In the present study we used the chick embryo chorioallantoic membrane (CAM) as an in-vivo assay for angiogenesis to assess the angiogenic potential of endometrium obtained at different stages of the menstrual cycle.

METHODS

Endometrial fragments were explanted onto the CAM and, after 4 days of incubation, slides of the treated area were taken in ovo through a microscope for computerized image analysis. The vascular density index (VDI), a stereological estimate of vessel number and length, was obtained by counting the intersections of vessels with five concentric circles of a circular grid superimposed on the computerized image.

RESULTS

We demonstrated that human endometrium has angiogenic potential throughout the menstrual cycle. Furthermore, there was a significant difference in angiogenic response between the stages of the menstrual cycle (P = 0.01). The VDIs of the early proliferative, early and late secretory stage were significantly higher than the VDI of the late proliferative phase.

CONCLUSIONS

Elongation of existing vessels during the early proliferative phase as well as growth and coiling of the spiral vessels during the secretory phase may demand far higher angiogenic activity than outgrowth and maintenance of vessels during the late proliferative phase.

The Mesothelium, Teflon or Velcro? Mesothelium in endometriosis pathogenesis

Sampson's transplantation theory for the pathogenesis of peritoneal endometriosis is widely accepted. The events that take place, however, on the cellular and subcellular level during the transition of endometrial tissue in the abdominal cavity into peritoneal endometriosis remain controversial. The mesothelium plays a central role in the debate on this subject. The interaction between endometrium and peritoneum has been studied in an in-vitro model using amnion, peritoneum and mesothelial cells in culture on the one hand and cyclic and menstrual endometrium on the other hand. The results of these studies indicate that (i) an intact mesothelial lining prevents adhesion of shed endometrial tissue, (ii) shed endometrial tissue adheres to the peritoneal extracellular matrix and (iii) menstrual effluent creates its own adhesion sites by damaging the mesothelial lining thus exposing the extracellular matrix. Therefore we conclude that the mesothelium has the properties of Teflon, while the extracellular matrix resembles Velcro.

Development of endometriosis-like lesions after transplantation of human endometrial fragments onto the chick embryo chorioallantoic membrane

The chick embryo chorioallantoic membrane (CAM) bioassay was used to investigate the early pathogenesis of endometriosis. Endometrial fragments were explanted onto the CAM. The grafts including the surrounding CAM were excised at 24, 48 or 72 h after explantation, fixed and embedded in paraffin. Immunohistochemical analysis was used to distinguish endometrial cells. To identify cells of human origin, in-situ hybridization was performed using a probe specific for human chromosome 1. After 24 h, direct contact between endometrial stromal as well as epithelial cells and the mesenchymal layer of the CAM was observed. Invasion of both stromal cells and intact endometrial glands into the mesenchymal layer was observed after 48 h. At 72 h, endometriosis-like lesions were observed in the mesenchymal layer. Positive staining with antibodies to vimentin and pan-cytokeratin was observed in the invading cells as well as in the lesions. In the lesions these positively stained cells showed in-situ hybridization signals for human chromosome 1, confirming their human origin. In conclusion, after 3 days of incubation, endometriosis-like lesions consisting of human endometrial glands and stromal cells were found in the mesenchymal layer of the CAM. These lesions apparently resulted from the invasion of intact human epithelial structures and stromal cells.

Menstruum induces changes in mesothelial cell morphology

In previous studies, we have shown that menstrual endometrium preferentially adheres to the subepithelial lining of the peritoneum. It remains to be elucidated, however, whether this damage is preexisting or inflicted by the menstrual tissue itself. We hypothesized that the menstrual tissue itself damages the peritoneum. To investigate this, the viability of menstrual endometrial tissue in peritoneal fluid (PF) was evaluated and the morphologic changes in the mesothelial cells were studied by in vitro cocultures of menstruum with mesothelial cell monolayers. Menstruum was collected with a menstrual cup. Endometrial tissue was isolated from the menstruum, resuspended in culture medium or in the cell-free fraction of PF and cultured for 24, 48 or 72 h. A 3(4, 5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) assay was performed to obtain a relative measure of viable adhered endometrial cells. Mesothelial cells isolated from human omental tissue were cultured on Matrigel or uncoated plastic. At confluence, overnight cocultures were performed and scanning electron microscopy was used to evaluate the morphologic changes. The viability of endometrial fragments was 84% (n = 36, p < 0.05), 82% (n = 27, not significant) and 104% (n = 14, not significant) when cultured in the cell-free fraction of PF for 24, 48 and 72 h, respectively, when compared to medium with 10% fetal calf serum. Menstrual endometrial fragments or menstrual serum added to and cocultured with mesothelial cells induced severe morphologic alterations of the latter, including retraction, shrinking and gap formation. Similar morphologic changes were observed when mesothelial cells were cocultured with menstrual endometrial fragments in PF or in culture inserts. Incubation with conditioned medium from cultured menstrual endometrium induced similar but less pronounced changes in morphology. In conclusion, menstrual endometrial fragments remain viable in PF in vitro for at least 72 h. Antegradely shed menstruum induces changes in mesothelial cell morphology, including retraction and shrinking with exposure of the underlying surface. These findings suggest that menstruum is harmful to the peritoneal lining. Therefore, by local destruction of the mesothelial layer, menstrual endometrium is able to create sites for adhesion.

Morphological changes in mesothelial cells induced by shed menstrual endometrium in vitro are not primarily due to apoptosis or necrosis

In a previous study on the pathogenesis of endometriosis, we observed that constituents of menstrual effluent induce morphological alterations in human mesothelial cells. In this study, we investigated whether these alterations were associated with apoptosis or necrosis or were the result of cellular remodelling. After overnight incubation of confluent monolayers of human omental mesothelial cells (HOMEC) with conditioned media prepared from menstrual effluent shed anterogradely, severe alterations in morphology were observed. Typical polygonal mesothelial cell cultures at confluency acquired elongated spindle morphology, resulting in gaps between the cells. In contrast, mesothelial cells from the control groups receiving culture medium only, retained a normal morphology. Immunofluorescence staining revealed that cytokeratin, vimentin and actin filaments were still present, homogeneously distributed in the cell cytoplasm following changes in morphology. To evaluate whether the morphological alterations were associated with apoptosis and/or necrosis, the cells were stained with the M30 CytoDeath antibody or annexin V with propidium iodide and analysed using flow cytometry. The results showed that only a small percentage (1-7%) of the affected HOMEC were undergoing apoptosis or necrosis. We conclude that the profoundly altered morphology of HOMEC is a result of cellular remodelling and that the role of apoptosis and necrosis is negligible. Soluble paracrine factors released by cells isolated from menstrual effluent shed anterogradely may induce a reorganization of the cytoskeleton. As a result, the underlying basement membrane will be exposed and the mesothelium may no longer prevent implantation of endometrium shed retrogradely into the peritoneum, thus facilitating the development of endometriosis.

Matrix metalloproteinases and their tissue inhibitors in antegradely shed menstruum and peritoneal fluid

OBJECTIVE

To investigate the expression of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in antegradely shed menstruum and peritoneal fluid.

DESIGN

A cell biological and immunohistochemical study.

SETTING

Tertiary care university medical center.

INTERVENTION(S)

Immunohistochemistry was performed on cryostat sections and cultures of menstrual endometrium. Zymography was used to characterize MMP activity in peritoneal fluid, in menstrual serum, and in conditioned medium. Western blot analysis was used to further identify the MMPs in these fluids.

MAIN OUTCOME MEASURE(S)

Staining of MMPs and TIMPs in cryostat sections and cultures and MMP expression and activity in peritoneal fluid and menstrual blood serum.

RESULT(S)

Strong staining for MMP-1 and MMP-3 was observed in stroma and for MMP-7 in epithelium. Matrix metalloproteinase-2 and MMP-9 were weakly expressed in stroma. Both TIMP-1 and TIMP-2 were expressed in menstrual endometrium. Menstrual serum showed a pattern of MMP activity on zymography different from peritoneal fluid. Western blot analysis showed the presence of MMP-7 and MMP-9 in menstrual serum.

CONCLUSION(S)

Antegradely shed menstrual endometrium expresses several MMPs and TIMPs, even after culturing for 24 hours. MMP activity in menstrual serum is different from and more intense than MMP activity in peritoneal fluid. These enzymes may be involved in the early invasion of menstrual endometrium into the extracellular matrix of the peritoneum.

Adhesion of menstrual endometrium to extracellular matrix: the possible role of integrin alpha(6)beta(1) and laminin interaction

Previous in-vitro studies have shown that the endometrium preferentially adheres to the extracellular matrix (ECM) of the amnion and peritoneum. This interaction probably involves adhesion molecules, e.g. integrins. We evaluated the expression of integrins in naturally shed menstrual endometrium and the adhesion pattern of this tissue to different components of the ECM. To identify integrins and matrix components involved, blocking studies were performed. Most of the 15 menstrual tissue samples showed positive staining for each of the integrins investigated, except alpha(4)beta(1). Compared with binding to collagen IV, which was set at 100%, adhesion to collagen I was 93% (not significant), to fibronectin 87% (P < 0.05), and to laminin 74% (P < 0.05). Scanning electron micoscopy showed that endometrium adhered to laminin but hardly spread, whereas spreading was observed when layered on the other coatings. Compared with the control (which was set at 100%), incubation with 4B4, a monoclonal antibody against the integrin beta(1) subunit, showed a significant reduction of adhesion (to approximately 50%; P < 0.05) when layered on laminin and a smaller reduction (to 82-86%; P < 0.05) when layered on the other three coatings. Incubation with antibody GOH3 against integrin alpha(6)beta(1) resulted in a similar reduction in adhesion to laminin. Incubation with an RGD peptide significantly reduced adhesion (to 84%; P < 0.05) when plated on fibronectin. In conclusion, antegradely shed menstrual endometrium expresses various integrins. It shows preferential attachment to collagen IV and collagen I, when compared with fibronectin and laminin. Blockage of the integrin beta(1) subunit resulted in greatest disruption to adhesion when layered on laminin, implying that the interaction was mediated by the alpha(6)beta(1) integrin. Since this adhesion was not completely blocked, other mechanisms are likely to be involved.

Adhesion of human endometrial fragments to peritoneum in vitro

OBJECTIVE

To evaluate the adhesion of endometrial fragments obtained during the proliferative phase of the menstrual cycle to fresh human peritoneum obtained during abdominal surgery.

DESIGN

A prospective, descriptive, morphologic and cell biologic study.

SETTING

Tertiary care university medical center.

PATIENT(S)

Six female volunteers.

INTERVENTION(S)

After endometrial biopsies performed during diagnostic laparoscopy, endometrial fragments were generated by enzymatic digestion and mechanical separation. Peritoneum was obtained during abdominal operations for benign indications.

MAIN OUTCOME MEASURE(S)

Adhesion of endometrial fragments was studied by histologic examination and scanning and transmission electron microscopy.

RESULT(S)

After incubation, the mesothelium was intact in some areas, whereas in other areas mesothelial cells were damaged or absent. Adhesion of endometrial fragments was observed only at locations where the basement membrane was exposed. In areas largely denuded of mesothelial cells, endometrial fragments spread over the basement membrane to form monolayers.

CONCLUSION(S)

Human peritoneum is suitable for studying the adhesion of endometrial fragments. Intact mesothelium prevents the adhesion of endometrial fragments, suggesting that trauma to the mesothelial lining is a prerequisite for endometrial cell adhesion.

Adhesion of shed menstrual tissue in an in-vitro model using amnion and peritoneum: a light and electron microscopic study

We have investigated the adhesion of endometrial tissue isolated from antegradely shed menstrual effluent to amnion and peritoneum. This endometrial tissue was cultured overnight on either side of intact and stripped amnion and on the mesothelial side of peritoneum. Light and electron microscopy were applied to evaluate adhesion. With light microscopy adhesion of endometrial fragments to stripped membranes was observed in nine out of 12 specimens and in 12 out of 13 specimens when layered on the extracellular matrix side of amnion. Adhesion when layered on the epithelial side was seen in only four out of 13 specimens. However, when using scanning electron microscopy adhesion of menstrual endometrial tissue could be visualized in all samples. Numerous adhering fragments were seen when layered on the extracellular matrix side of untreated amnion. On several occasions not only adhesion but also spreading of cells was observed. When layered on the epithelial side of untreated amnion or peritoneum, adhesion was exclusively seen at locations where the epithelium was damaged or absent. These findings were confirmed by transmission electron microscopy. These observations indicate that endometrial tissue isolated from antegradely shed menstrual effluent preferentially adheres to subepithelial structures of amnion and peritoneum. The lack of adhesion to epithelial cells suggests that an intact mesothelial lining prevents adhesion of menstrual endometrial tissue.

Adhesion of human endometrium to the epithelial lining and extracellular matrix of amnion in vitro: an electron microscopic study

One of the first steps in the pathogenesis of endometriosis is the attachment of the endometrium to the peritoneal lining. Since the peritoneum is extremely fragile and hard to obtain, amnion has been used as an in-vitro model to study adhesion. Scanning and transmission electron microscopy was applied to evaluate the adhesion of endometrial cells isolated in the proliferative and secretory phases of the menstrual cycle. Endometrial fragments obtained in either phase of the cycle were able to adhere to the extracellular matrix of the amnion. Fragments from proliferative phase endometrium showed active spreading and growth over the matrix surface, whereas fragments from secretory phase endometrium did not. Fragments from proliferative as well as secretory phase endometrium were able to adhere to the epithelial side of the amnion, but only at locations where the amniotic epithelium was damaged or partly absent. These observations indicate that the basement membrane and extracellular matrix provide a suitable substrate for endometrial cell attachment and growth and that endometrial cell adhesion occurs preferentially to subepithelial structures, whereas an intact epithelium prevents the adhesion of endometrial fragments to the amnion.

Uterine response to progesterone in prepubertal gilts

During early pregnancy, progesterone stimulates the secretion of proteins and other molecules that support the developing conceptus. Some gilts are able to support conceptus development as early as 110 days of age. The objective of this study was to evaluate the onset of responsiveness of the prepubertal uterus to progesterone. Thirty gilts were assigned to receive 2.2 mg progesterone kg-1 body mass per day or corn oil daily for 14 days starting at 6, 46, 76, 106, and 136 days of age. Hysterectomies were performed the day after the last treatment of progesterone, and the uterine horns were weighed and flushed with sterile saline (0.85% NaCl). Recovered flushings were analysed for total luminal protein, retinol binding protein, uteroferrin, prostaglandin E and prostaglandin F. An interaction between age and progesterone occurred for uterine wet mass (P < 0.001). Progesterone did not affect the uterine mass of gilts that underwent hysterectomy at 20 days of age, but did increase the uterine mass (P < 0.05) in other age groups. Progesterone increased (P < 0.01) the amount of total luminal protein in all but the youngest gilts. An increase in the amounts of retinol binding protein and uteroferrin (P < 0.001) by progesterone was first observed in 90-day-old gilts. Prostaglandins exhibited a different age-related pattern. The amount of prostaglandin E was increased (P < 0.001) by progesterone treatment in gilts aged 90-150 days, with a greater (P < 0.05) response at 120 days than at 90 days old. The response at 150 days old decreased (P < 0.05) to that observed at day 90. The response of prostaglandin F to progesterone followed a similar age-related pattern. Therefore, uterine responsiveness to progesterone develops between 20 and 90 days after birth, and uterine mass responds earlier than the secretory responses measured in our study.

Porcine conceptus proteins: antiviral activity and effect on 2',5'-oligoadenylate synthetase

Interferon-like proteins synthesized by conceptuses of domestic ruminants inhibit luteolysis during early pregnancy. Although pig conceptuses secrete trophoblast interferons during the period of CL maintenance, estrogen is involved with maintenance of the CL. The principal purposes of this work were to confirm production of trophoblast interferons by porcine conceptuses and to compare the effect of trophoblast interferons on endometrium of pigs and cattle. When measured using Madin-Darby bovine kidney (MDBK) cells challenged with vesicular stomatitis virus, antiviral activity in uterine flushings from cyclic gilts was not detectable throughout the estrous cycle; however, in pregnant gilts, antiviral activity increased from undetectable amounts to 4-11 x 10(3) U on Days 14, 16, and 18. Porcine embryos in culture produced 1,100 U/embryo/ml/24 h. Porcine conceptus secretory proteins induced 2',5'-oligo(A) synthetase in MDBK cells and in endometrial explants of cows but had no measurable effect on 2',5'-oligo(A) synthetase activity of endometrial explants of pigs. Similarly, endometrial 2',5'-oligo(A) synthetase of pregnant pigs was unaffected in vivo during the period of maximal synthesis of conceptus secretory proteins. Porcine conceptus secretory proteins produced no detectable increase in serum antiviral activity or 2',5'-oligo(A) synthetase activity of blood mononuclear leukocytes in utero-ovarian venous blood. These results suggest that conceptus interferons of pigs play different roles in the establishment of pregnancy compared to their roles in ruminants.