The effects of tamoxifen and estradiol on myometrial differentiation and organization during early uterine development in the CD1 mouse

Adenomyotic Lesions Are Induced in the Mouse Uterus after Exposure to NSAID and EE2 Mixtures at Environmental Doses

The aim of this study was to assess the long-term effect of exposure to environmentally relevant doses of non-steroidal anti-inflammatory drugs (NSAIDs; ibuprofen, and diclofenac) and 17β-ethinylestradiol (EE2) on the mouse uterus. NSAID-EE2 mixtures were administered in the drinking water from gestational day 8 until 8 weeks post-birth (i.e., during embryo development, lactation, puberty, and sexual maturity). The incidence of adenomyosis lesions (presence of endometrial glands in the inner myometrium) increased up to 60% in the uterus of 8-week-old exposed females (F1) and to 85% in F2 females (exposed father). Histological analysis revealed aberrant proliferation and apoptosis, vacuolization of epithelial cells, and increased incidence of abnormal glands in the luminal and glandular epithelium in F1 and F2 uteri. Moreover, myofibroblast proportion (alpha-smooth muscle actin (α-SMA) expression analysis) and collagen expression (Picrosirius red stain; a fibrosis hallmark) were increased in F1 and F2 endometrium. Connexin-43 was aberrantly distributed in the endometrial stroma and glands of F1 and F2 uteri. Conversely, uterine 17β-estradiol and progesterone levels were not affected in F1 and F2 females. These findings demonstrated that in mice, chronic exposure to NSAID and EE2 mixtures at environmental doses intergenerationally affects uterine physiology, particularly the endometrium. It may serve as a model to study the pathophysiology of human adenomyosis.

Differential expression of desmin in the uterine myometrium and cervix as a possible mechanism for successful parturition in rats

Expression of desmin, an intermediate filament, in the myometrium and cervix were investigated in peripartum rats (full term day 22 of pregnancy (DP22)). Des mRNA was expressed in lesser amounts in the cervix at peripartum (DP17 and 21, and day of birth 1 (DB1)), compared to those in the cervixes of ovariectomized rats. Immunohistochemical analysis revealed that desmin protein was diffusely present in the myometrium, and locally in the epithelium of the cervix. Western blot analysis showed that desmin protein levels in the myometrium increased 4- to 6-fold at DP17, 21 and DB1, and decreased rapidly at DB2 to the basal level observed in ovariectomized or non-pregnant rats. In contrast, cervical desmin protein levels increased approximately 10-fold at DP21 compared to those in ovariectomized rats, but decreased rapidly at DB1, indicating its decrease at parturition and an inconsistency between mRNA and protein expression. The administration of 17β-estradiol to ovariectomized rats increased desmin protein levels in the myometrium and cervix after 24 h. S-nitrosylated desmin protein was detected in the myometrium and cervix at DP21. The mRNA expression of inducible nitric oxide synthase was consistent with the expression of desmin protein. Thus, desmin, which is regulated by estradiol, is differentially expressed in the myometrium and cervix at peripartum possibly for successful pregnancy and parturition. In the cervix, desmin protein expression seems to be regulated by estradiol at the translational level. S-nitrosylation of desmin may have a potential role in the peripartum uterus.

Uterine Anteroposterior Diameter Measured by Transvaginal Sonography is a Predictor for Dysmenorrhea in Patients With and Without Endometriosis: A Pilot Study

PURPOSE

The aim of this study was to determine the correlation between uterine diameters and menstrual abdominal pain intensity in patients with and without endometriosis (EM), and the independent influence of EM on the pain intensity.

METHODS

Uterine diameters and the diagnosis of adenomyosis were ascertained by transvaginal ultrasonography (TVS). Menstrual abdominal pain intensity was estimated by visual analog scale (VAS). Linear regression was used to figure out the impact of uterine diameters and EM on the VAS scores. Logistic regression was used to calculate the correlation between uterine diameters and the diagnosis of adenomyosis. The cutoff values of uterine anteroposterior diameter (AD) to predict dysmenorrhea (VAS ≥ 4) and the diagnosis of adenomyosis were determined by receiver operating characteristic curves.

RESULTS

There were 220 patients with and 233 patients without EM included. Uterine AD independently correlated with the VAS scores in patients with (B = .230, P = .000) and without (B = .203, P = .000) EM. A uterine AD of 39.5 mm predicted dysmenorrhea in both groups. The presence of EM increased the VAS scores by 1.151 points when controlling for uterine diameters. Uterine AD also independently correlated with the diagnosis of adenomyosis under TVS in patients with (OR = 1.212, 95% CI = 1.130-1.301; P = .000) and without (OR = 1.192, 95% CI = 1.123-1.263; P = .000) EM. A uterine AD of 38.5 and 39.5 mm predicted the diagnosis of adenomyosis under TVS in patients with and without EM, respectively.

CONCLUSIONS

Increased uterine AD, which is probably ascribed to adenomyosis, plays an important role in augmented menstrual abdominal pain intensity. Meanwhile, the presence of EM reinforces the pain.

Establishment of a novel mouse model of adenomyosis suitable for longitudinal and quantitative analysis and perinatal outcome studies

The purpose of this study was to establish a novel mouse model of adenomyosis suitable for longitudinal and quantitative analyses and perinatal outcome studies. Using a 30 G needle, the entire uterine wall of one horn was mechanically punctured at a frequency of 100 times/1 cm (adenomyosis horn). The other horn was left unpunctured (control horn). Balb/c mice were sacrificed on day 14 (D14) or day 65 (D65) (n = 3 each). The uterus was fixed, paraffin-embedded, sliced, and stained. Lesions were detected and counted, and their volumes were measured. Cell proliferation and fibrosis were assessed by Ki67 and Masson's Trichrome staining, respectively. Blood vessels were detected using CD31 immunostaining. Some of the mice (n = 4), were mated and the date of delivery, litter size, number of implantations, and number and volume of postpartum lesions were measured. The number of lesions per horn did not differ between D14 and D65. The volume of the entire lesion was significantly greater on D65 than on D14 (p < 0.0001). The volume of the epithelial part of the lesion was significantly greater in D65 (p < 0.0001). The volume of the stromal part of the lesion was also greater on D65 (p < 0.0001). The percentage of Ki67 positive cells in the epithelial part of the lesion was significantly higher on D14 (p < 0.05). In contrast, the percentage of Ki67-positive cells in the stromal part was significantly higher on D65 (p < 0.01). Vascular density in the lesions was higher in on D65 (p < 0.05). The percentage of fibrotic area was significantly higher on D65 (p < 0.01). The date of delivery was slightly earlier than that reported for healthy mice of the same strain. The litter size was smaller than that reported in previous research. The number of implantation sites did not differ between the control and the adenomyosis horn. The number and volume of lesions did not differ between the non-pregnant and postpartum groups. This model can be applied to evaluate the pathogenesis of adenomyosis, validate the efficacy of therapeutic agents, and evaluate the effect of adenomyosis on pregnancy and vice versa.

Unveiling the Pathogenesis of Adenomyosis through Animal Models

Background: Adenomyosis is a common gynecological disorder traditionally viewed as “elusive”. Several excellent review papers have been published fairly recently on its pathogenesis, and several theories have been proposed. However, the falsifiability, explanatory power, and predictivity of these theories are often overlooked. Since adenomyosis can occur spontaneously in rodents and many other species, the animal models may help us unveil the pathogenesis of adenomyosis. This review critically tallies experimentally induced models published so far, with a particular focus on their relevance to epidemiological findings, their possible mechanisms of action, and their explanatory and predictive power. Methods: PubMed was exhaustively searched using the phrase “adenomyosis and animal model”, “adenomyosis and experimental model”, “adenomyosis and mouse”, and “adenomyosis and rat”, and the resultant papers were retrieved, carefully read, and the resultant information distilled. All the retrieved papers were then reviewed in a narrative manner. Results: Among all published animal models of adenomyosis, the mouse model of adenomyosis induced by endometrial–myometrial interface disruption (EMID) seems to satisfy the requirements of falsifiability and has the predictive capability and also Hill’s causality criteria. Other theories only partially satisfy Hill’s criteria of causality. In particular, animal models of adenomyosis induced by hyperestrogenism, hyperprolactinemia, or long-term exposure to progestogens without much epidemiological documentation and adenomyosis is usually not the exclusive uterine pathology consequent to those induction procedures. Regardless, uterine disruption appears to be a necessary but not sufficient condition for causing adenomyosis. Conclusions: EMID is, however, unlikely the sole cause for adenomyosis. Future studies, including animal studies, are warranted to understand how and why in utero and/or prenatal exposure to elevated levels of estrogen or estrogenic compounds increases the risk of developing adenomyosis in adulthood, to elucidate whether prolactin plays any role in its pathogenesis, and to identify sufficient condition(s) that cause adenomyosis.

The Potential Relationship Between Environmental Endocrine Disruptor Exposure and the Development of Endometriosis and Adenomyosis

Women with endometriosis, the growth of endometrial glands and stroma outside the uterus, commonly also exhibit adenomyosis, the growth of endometrial tissues within the uterine muscle. Each disease is associated with functional alterations in the eutopic endometrium frequently leading to pain, reduced fertility, and an increased risk of adverse pregnancy outcomes. Although the precise etiology of either disease is poorly understood, evidence suggests that the presence of endometriosis may be a contributing factor to the subsequent development of adenomyosis as a consequence of an altered, systemic inflammatory response. Herein, we will discuss the potential role of exposure to environmental toxicants with endocrine disrupting capabilities in the pathogenesis of both endometriosis and adenomyosis. Numerous epidemiology and experimental studies support a role for environmental endocrine disrupting chemicals (EDCs) in the development of endometriosis; however, only a few studies have examined the potential relationship between toxicant exposures and the risk of adenomyosis. Nevertheless, since women with endometriosis are also frequently found to have adenomyosis, discussion of EDC exposure and development of each of these diseases is relevant. We will discuss the potential mechanisms by which EDCs may act to promote the co-development of endometriosis and adenomyosis. Understanding the disease-promoting mechanisms of environmental toxicants related to endometriosis and adenomyosis is paramount to designing more effective treatment(s) and preventative strategies.

Mode Switch of Ca2 + Oscillation-Mediated Uterine Peristalsis and Associated Embryo Implantation Impairments in Mouse Adenomyosis

Adenomyosis is a debilitating gynecological disease of the uterus with no medicinal cure. The tissue injury and repair hypothesis for adenomyosis suggests that uterine hyperperistalsis or dysperistalsis plays a pivotal role in establishing adenomyotic lesions. However, specific impairments in uterine peristalsis and the underlying cellular signals for these changes in adenomyosis remain elusive. Here, we report a precision-cut uterine slice preparation that preserves in vivo uterine architecture and generates peristalsis similar to that seen in the whole uterus. We found that uterine peristalsis in neonatal mice at day 14 and adult mice at day 55 presents as bursts with multiple peaks induced by intracellular Ca²⁺ oscillations. Using a mouse model of adenomyosis induced by tamoxifen, a selective estrogen receptor modulator, we discovered that uterine peristalsis and Ca²⁺ oscillations from adenomyotic uteri on days 14 and 55 become spikes (single peaks) with smaller amplitudes. The peak frequency of Ca²⁺ oscillations or peristalsis does not show a difference between control and adenomyotic mice. However, both the estimated force generated by uterine peristalsis and the total Ca²⁺ raised by Ca²⁺ oscillations are smaller in uteri from adenomyotic mice. Uteri from adenomyotic mice on day 14, but not on day 55, exhibit hyperresponsiveness to oxytocin. Embryo implantations are decreased in adenomyotic adult mice. Our results reveal a mode switch from bursts to spikes (rather than an increased peak frequency) of uterine Ca²⁺ oscillations and peristalsis and concurrent hyperresponsiveness to oxytocin in the neonatal stage are two characteristics of adenomyosis. These characteristics may contribute to embryo implantation impairments and decreased fertility in adenomyosis.

In the mouse, prostaglandin D2 signalling protects the endometrium against adenomyosis

Adenomyosis is characterised by epithelial gland and mesenchymal stroma invasion of the uterine myometrium. Adenomyosis is an oestrogen-dependent gynaecological disease in which a number of factors, such as inflammatory molecules, prostaglandins (PGs), angiogenic factors, cell proliferation and extracellular matrix remodelling proteins, also play a role as key disease mediators. In this study, we used mice lacking both lipocalin and hematopoietic-PG D synthase (L- and H-Pgds) genes in which PGD2 is not produced to elucidate PGD2 roles in the uterus. Gene expression studied by real-time PCR and hormone dosages performed by ELISA or liquid chromatography tandem mass spectroscopy in mouse uterus samples showed that components of the PGD2 signalling pathway, both PGDS and PGD2-receptors, are expressed in the mouse endometrium throughout the oestrus cycle with some differences among uterine compartments. We showed that PGE2 production and the steroidogenic pathway are dysregulated in the absence of PGD2. Histological analysis of L/H-Pgds-/- uteri, and immunohistochemistry and immunofluorescence analyses of proliferation (Ki67), endothelial cell (CD31), epithelial cell (pan-cytokeratin), myofibroblast (α-SMA) and mesenchymal cell (vimentin) markers, identify that 6-month-old L/H-Pgds-/- animals developed adenomyotic lesions, and that disease severity increased with age. In conclusion, this study suggests that the PGD2 pathway has major roles in the uterus by protecting the endometrium against adenomyosis development. Additional experiments, using for instance transcriptomic approaches, are necessary to fully determine the molecular mechanisms that lead to adenomyosis in L/H-Pgds-/- mice and to confirm whether this strain is an appropriate model for studying the human disease.

Evaluation of Development of the Rat Uterus as a Toxicity Biomarker

The developing uterus is highly sensitive to a brief exposure to different substances, in particular those with endocrine-disrupting activity. Thus, exposure to environmental, nutritional, chemical, and other xenobiotic factors affecting signaling events during critical organizational periods can alter the normal course of uterine development with lasting consequences. In this chapter, we provide an experimental protocol to evaluate the development of the rat uterus as a toxicity biomarker at two different developmental time points: (1) the neonatal period, on postnatal day (PND) 8, and (2) the prepubertal period, on PND21. In this experimental approach, we propose to assess: (1) uterine morphology and cytodifferentiation, (2) uterine cell proliferation, and (3) the expression of proteins involved in uterine organogenetic differentiation. All these morphological and molecular markers are useful tools to determine the consequences of exposure to toxicants with the potential to disrupt the uterine development.

Animal Models of Adenomyosis

Adenomyosis is a nonmalignant uterine disorder in which endometrial tissue exists within and grows into the myometrium. Animal models have generated limited insight into the still-unclear pathogenesis of adenomyosis, provided a platform for preclinical screening of many drugs and compounds with potential as therapeutics, and elucidated mechanisms underlying the pain and fertility issues that occur in many women with the disease. Spontaneous adenomyosis has been studied in nonhuman primates, primarily in the form of case reports. Adenomyosis is routinely experimentally induced in mice through methods such as neonatal tamoxifen exposure, pituitary engraftment, and human tissue xenotransplantation. Several studies have also reported hormonal or environmental toxicant exposures that give rise to murine adenomyosis, and genetically engineered models have been created that recapitulate the human-like condition, most notably involving alteration of β-catenin expression. This review describes the animal models for adenomyosis and their contributions to our understanding of the factors underpinning the development of symptoms. Animal models represent a unique opportunity for understanding the molecular basis of adenomyosis and developing efficacious treatment options for affected women. Herein, we assess their different potentials and limitations with regard to identification of new therapeutic interventions and reflect on future directions for research and drug validation.

The development of the human uterus: morphogenesis to menarche

There is emerging evidence that early uterine development in humans is an important determinant of conditions such as ontogenetic progesterone resistance, menstrual preconditioning, defective deep placentation and pre-eclampsia in young adolescents. A key observation is the relative infrequency of neonatal uterine bleeding and hormone withdrawal at birth. The origin of the uterus from the fusion of the two paramesonephric, or Müllerian, ducts was described almost 200 years ago. The uterus forms around the 10th week of foetal life. The uterine corpus and the cervix react differently to the circulating steroid hormones during pregnancy. Adult uterine proportions are not attained until after puberty. It is unclear if the endometrial microbiome and immune response-which are areas of growing interest in the adult-play a role in the early stages of uterine development. The aim is to review the phases of uterine development up until the onset of puberty in order to trace the origin of abnormal development and to assess current knowledge for features that may be linked to conditions encountered later in life. The narrative review incorporates literature searches of Medline, PubMed and Scopus using the broad terms individually and then in combination: uterus, development, anatomy, microscopy, embryology, foetus, (pre)-puberty, menarche, microbiome and immune cells. Identified articles were assessed manually for relevance, any linked articles and historical textbooks. We included some animal studies of molecular mechanisms. There are competing theories about the contributions of the Müllerian and Wolffian ducts to the developing uterus. Endometrium features are suggestive of an oestrogen effect at 16-20 weeks gestation. The discrepancy in the reported expression of oestrogen receptor is likely to be related to the higher sensitivity of more recent techniques. Primitive endometrial glands appear around 20 weeks. Features of progestogen action are expressed late in the third trimester. Interestingly, progesterone receptor expression is higher at mid-gestation than at birth when features of endometrial maturation are rare. Neonatal uterine bleeding occurs in around 5% of neonates. Myometrial differentiation progresses from the mesenchyme surrounding the endometrium at the level of the cervix. During infancy, the uterus and endometrium remain inactive. The beginning of uterine growth precedes the onset of puberty and continues for several years after menarche. Uterine anomalies may result from fusion defects or atresia of one or both Müllerian ducts. Organogenetic differentiation of Müllerian epithelium to form the endometrial and endocervical epithelium may be independent of circulating steroids. A number of genes have been identified that are involved in endometrial and myometrial differentiation although gene mutations have not been demonstrated to be common in cases of uterine malformation. The role, if any, of the microbiome in relation to uterine development remains speculative. Modern molecular techniques applied to rodent models have enhanced our understanding of uterine molecular mechanisms and their interactions. However, little is known about functional correlates or features with relevance to adult onset of uterine disease in humans. Prepubertal growth and development lends itself to non-invasive diagnostics such as ultrasound and MRI. Increased awareness of the occurrence of neonatal uterine bleeding and of the potential impact on adult onset disease may stimulate renewed research in this area.

Shi Xiao San ameliorates the development of adenomyosis in an ICR mouse model

The use of Shi Xiao San (SXS), composed of Pollen Typhae Angustifoliae and Faeces Trogopterori, can be traced back to the Song dynasty. Traditionally, SXS has been used to treat irregular menstruation, pelvic pain, progressive dysmenorrhea, and postpartum lochiorrhea. The management of adenomyosis (AM) is challenging and to the best of our knowledge there are currently no effective therapeutic strategies. Therefore, the aim of the present study was to investigate the effect of SXS on the development of adenomyosis in a mouse model. AM was induced in 60 neonatal female ICR mice by administering tamoxifen; 10 randomly selected mice were used for model identification via histopathological examination and 10 mice treated with the solvent alone were used as the normal controls. A total of sixty days after birth, the mice treated with AM were randomly divided into four groups and administered one of the following treatments: Low-dose SXS (55 mg/kg); high-dose SXS (110 mg/kg); danazol (1 mg/20 g body weight); or no treatment (model group); at the same time, the normal control group received no treatment. After 2 months of treatment, hotplate and tail-flick tests were used to assess the response to noxious thermal stimuli in the mice, and plasma samples were collected to measure corticosterone levels. Hematoxylin and eosin staining scores of myometrial infiltration and the number of AM nodules were evaluated. Furthermore, the expression of genes associated with AM-related pain was also analyzed. The results from the present study indicated that treatment with SXS decreased myometrial infiltration, alleviated generalized hyperalgesia, and lowered plasma corticosterone levels in mice with induced AM. These findings suggest that SXS effectively attenuated the development of AM, and may serve as a promising treatment approach for AM treatment.

Effects of diisononyl phthalate on osteopenia in intact mice

Osteopenia is characterized by bone loss and deterioration of trabecular bone, which leads to osteoporotic fractures. This disease is highly prevalent in industrialized areas and is associated with exposure to endocrine disrupting chemicals (EDCs). Diisononyl phthalate (DINP) is one of these EDCs and is mainly used as a plasticizer in flexible polyvinyl chloride (PVC) products. Although it is well known that exposure to DINP is harmful to humans, no studies have been reported concerning its contribution to osteopenia. Therefore, in this study, we injected DINP (2, 20, and 200mg/kg) into C3H/HeN mice for 6weeks and found that the uterus weight, bone (femur and tibia) weight, and bone length of the DINP-exposed mice were reduced compared to those of the SHAM group. On the other hand, body weight, the serum alkaline phosphatase (ALP) and inorganic phosphorus (IP) levels in the DINP treated mice were increased compared with those of the SHAM group. The tartrate-resistant acid phosphatase (TRAP) activity (bone resorption marker) was increased and the bone alkaline phosphatase (BALP) activity was lowered by the treatment with DINP as compared with the SHAM group. Furthermore, the microarchitecture of the femur and tibia in the intact mice was destroyed by the DINP injection. The tissue volume (TV), bone volume (BV), BV/TV, bone surface (BS), BS/TV, trabecular thickness (Tb.Th), and trabecular number (Tb.N) were reduced and the trabecular pattern factor (Tb.Pf), structure model index (SMI), and trabecular separation (Tb.Sp) were increased by the DINP injection. The bone mineral density (BMD) of the femur and tibia was lower in the DINP group than in the SHAM group. These results indicate that DINP contributes to an increased risk of osteopenia via destruction of the microarchitecture and enhancement of osteoclast activity.

A shortened tamoxifen induction scheme to induce CreER recombinase without side effects on the male mouse skeleton

The selective estrogen receptor modulator tamoxifen exerts estrogen agonistic or antagonistic actions on several tissues, including bone. The off-target effects of tamoxifen are one of the most widely recognized pitfalls of tamoxifen-inducible Cre recombinases (CreERs), potentially confounding the phenotypic findings. Still, the validation of tamoxifen induction schemes that minimize the side effects of the drug has not been addressed. Here, we compared the side effects on the skeleton and other androgen-responsive targets of a shortened tamoxifen regimen (2 doses of 190 mg/kg body weight by oral gavage) to a standard protocol (4 doses) and determined their efficiency in inducing CreER-mediated gene deletion. In addition, both a vehicle- and a 10-dose group, which served as a positive control for tamoxifen side effects, were also included. For this purpose, we generated male mice with a floxed androgen receptor (AR) and a neuron-specifically expressed CreER. Treatment with two doses of tamoxifen was the only regimen that did not diminish androgenic bioactivity, as assessed by both seminal vesicles and levator ani/bulbocavernosus muscle weights and serum testosterone concentrations. Similarly, trabecular and cortical femoral bone structure were dramatically altered by both the standard and high-dose protocols but not by the shortened version. Serum osteocalcin and bone-gene expression analyses confirmed the absence of effects on bone by 2 doses of tamoxifen. This protocol decreased AR mRNA levels efficiently and specifically in the nervous system. Thus, we optimized a protocol for tamoxifen-induced CreER gene deletion in mice without off-target effects on bone and male reproductive organs.

An optimized, broadly applicable piggyBac transposon induction system

The piggyBac (PB) transposon has been used in a number of biological applications. The insertion of PB transposons into the genome can disrupt genes or regulatory regions, impacting cellular function, so for many experiments it is important that PB transposition is tightly controlled. Here, we systematically characterize three methods for the post-translational control of the PB transposon in four cell lines. We investigated fusions of the PB transposase with ERT2 and two degradation domains (FKBP-DD, DHFR-DD), in multiple orientations, and determined (i) the fold-induction achieved, (ii) the absolute transposition efficiency of the activated construct and (iii) the effects of two inducer molecules on cellular transcription and function. We found that the FKBP-DD confers the PB transposase with a higher transposition activity and better dynamic range than can be achieved with the other systems. In addition, we found that the FKBP-DD regulates transposon activity in a reversible and dose-dependent manner. Finally, we showed that Shld1, the chemical inducer of FKBP-DD, does not interfere with stem cell differentiation, whereas tamoxifen has significant effects. We believe the FKBP-based PB transposon induction will be useful for transposon-mediated genome engineering, insertional mutagenesis and the genome-wide mapping of transcription factor binding.

Molecular Characteristics of the Endometrium in Uterine Adenomyosis and Its Biochemical Microenvironment

Adenomyosis, which manifests with focally or diffusely scattered endometrial tissue within the uterine myometrium, is an endometriosis-like disease with controversial pathogenesis and compromised reproductive outcomes. This review, including the in vitro and in vivo studies performed on human or mouse models, is aimed to summarize the specific molecular characteristics of endometrium in the biochemical microenvironments of uterine adenomyosis. Many studies attributed the endometrium as the main cause of pathogenesis, with evidence of differential genetic expression and/or epigenetic modulation as well as estrogen-induced epithelial-mesenchymal transition. However, some studies indicated that the myometrium could play a role in the development of disease, based on findings of smooth muscle metaplasia and/or fibroblast-to-myofibroblast transdifferentiation by the influence of local biochemical factors. To date, it remains unclear whether adenomyosis is a genetically determined or a microenvironmentally induced disorder or whether the dysregulation of local factors may elicit the alteration of genetic expression in the endometrium. Similarly, it is uncertain whether the endometrial characteristics would remain consistent or could change along with a woman's reproductive life. Further longitudinal studies of the epigenetic controls or system biology are needed to elucidate the pathogenesis. Discovery of effective conservative treatments to improve the reproductive outcomes of patients with adenomyosis is still warranted.

Decreased Endometrial Expression of Leukemia Inhibitory Factor Receptor Disrupts the STAT3 Signaling in Adenomyosis During the Implantation Window

BACKGROUND

Adenomyosis was found to have negative impacts on embryo implantation. Leukemia inhibitory factor (LIF), proposed to be a molecular marker for endometrial receptivity, works through the LIF receptor (LIFR) on both the embryo and the endometrium. We aimed to evaluate the endometrial expression of LIF and LIFR and its subsequent signaling in patients with adenomyosis during the window of implantation (WOI).

METHODS

Endometrium was obtained during the WOI from patients with adenomyosis (age <45 years) who underwent hysterectomy and from age-matched controls who had no endometriosis or adenomyosis. The LIF and LIFR expressions were measured by polymerase chain reaction for messenger RNA expression, immunohistochemistry for protein intensity and localization, and immunofluorescent staining for colocalization. The ratio of signal transducer and activator of transcription 3 (STAT3) to extracellular signal-regulated kinase (ERK) phosphorylation was measured by Western blot of both the endometrium and the isolated human endometrial stromal cells (ESCs).

RESULTS

Patients with adenomyosis showed significantly and parallelly reduced LIF and LIFR expressions in the eutopic endometrium during WOI as compared with the control women and subsequently with remarkably reduced activation of STAT3 and ERK signaling. The significantly increased STAT3 and ERK phosphorylation induced by the LIF treatment in the cultured ESCs supported the linkage between the LIF-LIFR reaction and the signaling cascade.

CONCLUSION

Significant reduction in LIFR expression and the reduced activation of subsequent signaling strongly suggest a working model of how the implantation markers, LIF, may affect the endometrium of patients with adenomyosis. These molecular changes supported the declined implantation rates reported in patients with adenomyosis.

Mouse models of liver cancer: Progress and recommendations

To clarify the pathogenesis of hepatocellular carcinoma (HCC) and investigate the effects of potential therapies, a number of mouse models have been developed. Subcutaneous xenograft models are widely used in the past decades. Yet, with the advent of in vivo imaging technology, investigators are more and more concerned with the orthotopic models nowadays. Genetically engineered mouse models (GEM) have greatly facilitated studies of gene function in HCC development. Recently, GEM of miR-122 and miR-221 provided new approaches for better understanding of the in vivo functions of microRNA in hepatocarcinogenesis. Chemically induced liver tumors in animals share many of the morphological, histogenic, and biochemical features of human HCC. Yet, the complicated and obscure genomic alternation restricts their applications. In this review, we highlight both the frequently used mouse models and some emerging ones with emphasis on their merits or defects, and give advises for investigators to chose a “best-fit” animal model in HCC research.

Transforming growth factor β1 signaling coincides with epithelial-mesenchymal transition and fibroblast-to-myofibroblast transdifferentiation in the development of adenomyosis in mice

STUDY QUESTION

Do platelets have any role in the development of adenomyosis?

SUMMARY ANSWER

Activated platelets coincide with the release of transforming growth factor (TGF)-β1 and induction of the TGF-β/Smad signaling pathway as well as evidence of epithelial-mesenchymal transition (EMT) and fibroblast-to-myofibroblast transdifferentiation (FMT) in a mouse model of adenomyosis, resulting ultimately in fibrosis, as in adenomyosis.

WHAT IS KNOWN ALREADY

Both EMT and FMT are known to play vital roles in fibrogenesis in general and in endometriosis in particular. EMT has been implicated in the development of adenomyosis, but this was based primarily on cross-sectional observation. It is unclear as to whether adenomyotic lesions and their microenvironment have the machinery to promote EMT and FMT, resulting ultimately in fibrosis. There has not been any published study on the role of platelets in the development of adenomyosis, even though adenomyotic lesions undergo repeated cycles of tissue injury and repair, which implicates the involvement of platelets and constitutes an environment conducive for fibrogenesis.

STUDY DESIGN, SIZE, DURATION

Adenomyosis was induced in 28 female ICR mice by neonatal dosing of tamoxifen. Another 32 were neonatally dosed without tamoxifen. These mice were sacrificed serially and their tissue samples were subsequently evaluated.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Female ICR mice with and without induced adenomyosis were sacrificed in batch at 5, 10, 15, 42 and 60 days of age. The depth of myometrial infiltration of endometrial tissues was assessed and immunohistochemistry analysis of biomarkers of EMT and FMT, as well as TGF-β1, phosphorylated Smad3 (p-Smad3) and markers of proliferation, angiogenesis and extracellular matrix (ECM) deposits was performed in ectopic (for adenomyotic mice) and eutopic (controls) endometrial tissue samples. Masson trichrome and Van Gieson stainings were performed to quantify the extent of fibrosis in lesions. Progesterone receptor isoform B (PR-B) staining also was performed.

MAIN RESULTS AND THE ROLE OF CHANCE

While TGF-β1 immunoreactivity was consistently low in control endometrium, its level was increased dramatically starting from Day 10, along with the extent of platelet aggregation. Staining for TGF-β1 and p-Smad3 increased progressively as adenomyosis progressed, along with markers for proliferation, angiogenesis and ECM deposits. Consistently, staining of vimentin (a marker for stromal or mesenchymal cells) was also increased while that of E-cadherin (a marker for epithelial cells) was reduced. PR-B staining also decreased progressively. Starting from Day 42, α-SMA staining, a marker for myofibroblasts, was elevated in lesions, while in control endometrium, it was negative. Concomitantly, the extent of fibrosis also was increased.

LIMITATIONS, REASONS FOR CAUTION

This study is limited by the use of histochemistry and immunohistochemistry analyses only and the lack of intervention.

WIDER IMPLICATIONS OF THE FINDINGS

Like their endometriotic counterpart, adenomyotic lesions and their microenvironment may contain all the necessary molecular machinery to promote fibrogenesis. Platelet-induced activation of the TGF-β/Smad signaling pathway may be a driving force in EMT and FMT in the development of adenomyosis, leading to fibrosis. This study provides the first piece of evidence that adenomyotic lesions are wounds that undergo repeated injury and healing, and as such, platelets play critical roles in the development of adenomyosis. It suggests the potential for the use of anti-platelet therapy in the treatment of adenomyosis, and also opens a new venue for developing novel biomarkers for diagnostic or prognostic purposes.

STUDY FUNDING/COMPETING INTERESTS

Support for data collection and analysis was provided by grants from the National Science Foundation of China. None of the authors has anything to disclose.

Molecular mechanisms of tamoxifen-associated endometrial cancer (Review)

Tamoxifen has been prescribed to millions of females for breast cancer prevention or treatment. However, tamoxifen is known to significantly enhance the risk of developing endometrial lesions, including hyperplasia, polyps, carcinomas, and sarcoma. Notably, tamoxifen-associated endometrial cancer often has a poor clinical outcome. Understanding the molecular mechanism of tamoxifen-induced endometrial cancer is essential for developing strategies that minimize tamoxifen’s effects on the endometrium without jeopardizing its breast cancer treatment effects. However, this understanding remains limited. Tamoxifen appears to mediate its effect on endometrial cells through estrogenic and non-genomic pathways, rather than introducing a genomic alteration as a carcinogen. Although tamoxifen functions as an agonist and promotes cell proliferation in endometrial cancer, it also displays antagonist activity towards some estrogen targets. Alterations in estrogen receptor-α and its isoforms, as well as the membrane associated estrogen receptor G protein-coupled receptor 30, have been observed with tamoxifen-exposed endometrial cells, and likely mediate the effects of tamoxifen on endometrial cancer cell proliferation and invasion. In addition, gene profile studies of short-term exposure to tamoxifen indicate that the majority of tamoxifen targets are tamoxifen-specific. However, the tamoxifen regulated gene targets that are involved in mediating the effects of long-term exposure to tamoxifen are not yet fully understood. Recent progress has indicated a potential role of unfolded protein response and mammalian target of rapamycin signaling in tamoxifen-associated endometrial cancer. In the future, studies focusing on long-term effects of tamoxifen exposure are required to understand the molecular mechanisms of tamoxifen-associated endometrial cancer.

TGFBR1 is required for mouse myometrial development

The smooth muscle layer of the uterus (ie, myometrium) is critical for a successful pregnancy and labor. We have shown that the conditional deletion of TGFβ type 1 receptor (TGFBR1) in the female reproductive tract leads to remarkable smooth muscle defects. This study was aimed at defining the cellular and molecular basis of the myometrial defects. We found that TGFBR1 is required for myometrial configuration and formation during early postnatal uterine development. Despite the well-established role of TGFβ signaling in vascular smooth muscle cell differentiation, the majority of smooth muscle genes were expressed in Tgfbr1 conditional knockout (cKO) uteri at similar levels as controls during postnatal uterine development, coinciding with the presence but abnormal distribution of proteins for select smooth muscle markers. Importantly, the uteri of these mice had impaired synthesis of key extracellular matrix proteins and dysregulated expression of platelet-derived growth factors. Furthermore, platelet-derived growth factors induced the migration of uterine stromal cells from both control and Tgfbr1 cKO mice in vitro. Our results suggest that the myometrial defects in Tgfbr1 cKO mice may not directly arise from an intrinsic deficiency in uterine smooth muscle cell differentiation but are linked to the impaired production of key extracellular matrix components and abnormal uterine cell migration during a critical time window of postnatal uterine development. These findings will potentially aid in the design of novel therapies for reproductive disorders associated with myometrial defects.

Estradiol and tamoxifen enhance invasion of endometrial stromal cells in a three-dimensional coculture model of adenomyosis

OBJECTIVE

To examine the effect of estradiol alone or with progesterone and tamoxifen on the depth of invasion of endometrial stromal cells from women with and without adenomyosis in a three-dimensional (3D) coculture model that includes myocytes.

DESIGN

Case-controlled, blinded comparison.

SETTING

Medical school department.

PATIENT(S)

Premenopausal women with and without uterine adenomyosis.

INTERVENTION(S)

Human endometrial stromal and myometrial cells grown in a 3D coculture with crossover between cells from uteri with and without adenomyosis; cocultures treated with tamoxifen, estradiol alone, or estradiol with progesterone.

MAIN OUTCOME MEASURE(S)

Depth of stromal cell invasion into a collagen matrix.

RESULT(S)

The depth of invasion for adenomyotic stromal cells was statistically significantly higher than for the control stromal cells, whether grown on plain collagen, on collagen containing control or adenomyotic muscle cells. The addition of estradiol or tamoxifen, but not the estradiol and progesterone combination, increased the depth of invasion of both adenomyotic stromal cells and control stromal cells in all cell combinations. When grown on plain collagen, the depth of invasion for control stromal cells and adenomyotic stromal cells increased by 126% and 93% with the use of tamoxifen, and by 71% and 50%, with the use of estradiol.

CONCLUSION(S)

Both estradiol and tamoxifen enhance stromal cell invasion, but the greater depth of invasion of adenomyotic stromal cells and the enhancing effect of adenomyotic muscle were maintained under all experimental conditions, suggesting an inherent predisposition in affected women.

Illuminating cancer systems with genetically engineered mouse models and coupled luciferase reporters in vivo

Bioluminescent imaging (BLI) is a powerful noninvasive tool that has dramatically accelerated the in vivo interrogation of cancer systems and longitudinal analysis of mouse models of cancer over the past decade. Various luciferase enzymes have been genetically engineered into mouse models (GEMM) of cancer, which permit investigation of cellular and molecular events associated with oncogenic transcription, posttranslational processing, protein-protein interactions, transformation, and oncogene addiction in live cells and animals. Luciferase-coupled GEMMs ultimately serve as a noninvasive, repetitive, longitudinal, and physiologic means by which cancer systems and therapeutic responses can be investigated accurately within the autochthonous context of a living animal.

Distinct function of estrogen receptor α in smooth muscle and fibroblast cells in prostate development

Estrogen signaling, through estrogen receptor (ER)α, has been shown to cause hypertrophy in the prostate. Our recent report has shown that epithelial ERα knockout (KO) will not affect the normal prostate development or homeostasis. However, it remains unclear whether ERα in different types of stromal cells has distinct roles in prostate development. This study proposed to elucidate how KO of ERα in the stromal smooth muscle or fibroblast cells may interrupt cross talk between prostate stromal and epithelial cells. Smooth muscle ERαKO (smERαKO) mice showed decreased glandular infolding with the proximal area exhibiting a significant decrease. Fibroblast ERαKO mouse prostates did not exhibit this phenotype but showed a decrease in the number of ductal tips. Additionally, the amount of collagen observed in the basement membrane was reduced in smERαKO prostates. Interestingly, these phenotypes were found to be mutually exclusive among smERαKO or fibroblast ERαKO mice. Compound KO of ERα in both fibroblast and smooth muscle showed combined phenotypes from each of the single KO. Further mechanistic studies showed that IGF-I and epidermal growth factor were down-regulated in prostate smooth muscle PS-1 cells lacking ERα. Together, our results indicate the distinct functions of fibroblast vs. smERα in prostate development.

The pathophysiology of uterine adenomyosis: an update

The diagnosis of adenomyosis using noninvasive techniques such as vaginal ultrasounds and magnetic resonance has clear clinical applications and has renewed the interest in the pathogenesis of uterine adenomyosis. However, the research remains hampered by the lack of consensus on the classification of lesions. Magnetic resonance imaging and transvaginal ultrasound have comparable diagnostic accuracy. Minimal interventional biopsy techniques have recently been introduced. This article reviews human and animal studies and provides an update on the pathophysiology of adenomyosis. Recent views on the pathogenesis and links with endometriosis are discussed.

Conditional gene expression in the mouse inner ear using Cre-loxP

In recent years, there has been significant progress in the use of Cre-loxP technology for conditional gene expression in the inner ear. Here, we introduce the basic concepts of this powerful technology, emphasizing the differences between Cre and CreER. We describe the creation and Cre expression pattern of each Cre and CreER mouse line that has been reported to have expression in auditory and vestibular organs. We compare the Cre expression patterns between Atoh1-CreER(TM) and Atoh1-CreER(T2) and report a new line, Fgfr3-iCreER(T2), which displays inducible Cre activity in cochlear supporting cells. We also explain how results can vary when transgenic vs. knock-in Cre/CreER alleles are used to alter gene expression. We discuss practical issues that arise when using the Cre-loxP system, such as the use of proper controls, Cre efficiency, reporter expression efficiency, and Cre leakiness. Finally, we introduce other methods for conditional gene expression, including Flp recombinase and the tetracycline-inducible system, which can be combined with Cre-loxP mouse models to investigate conditional expression of more than one gene.

Mouse models of cancer

Genetically engineered mouse models have significantly contributed to our understanding of cancer biology. They have proven to be useful in validating gene functions, identifying novel cancer genes and tumor biomarkers, gaining insight into the molecular and cellular mechanisms underlying tumor initiation and multistage processes of tumorigenesis, and providing better clinical models in which to test novel therapeutic strategies. However, mice still have significant limitations in modeling human cancer, including species-specific differences and inaccurate recapitulation of de novo human tumor development. Future challenges in mouse modeling include the generation of clinically relevant mouse models that recapitulate the molecular, cellular, and genomic events of human cancers and clinical response as well as the development of technologies that allow for efficient in vivo imaging and high-throughput screening in mice.

Estrogen and progesterone receptor isoform distribution through the menstrual cycle in uteri with and without adenomyosis

OBJECTIVE

To test the hypothesis that the expression of the different isoforms of the estrogen receptor alpha (ER-α) and beta (ER-β) and the progesterone receptor A (PR-A) and B (PR-B) would be differentially modulated in uteri with adenomyosis compared with controls and that modulation would be related to the menstrual cycle.

DESIGN

Case control, blinded comparison.

SETTING

University department.

PATIENT(S)

54 premenopausal women with and 35 without uterine adenomyosis as the sole pathology.

INTERVENTION(S)

Multiple samples studied using immunohistochemistry for estrogen and progesterone receptors.

MAIN OUTCOME MEASURE(S)

Histomorphometric analysis of receptor expression.

RESULT(S)

The ER-α expression in the adenomyotic endometrium was different from that of the normal endometrium and the foci in the midsecretory phase of the cycle, but expression of ER-α in the inner and outer myometrium was not statistically significantly different. The ER-β expression was statistically significantly elevated in the adenomyotic functionalis gland during the proliferative phase and throughout the myometrium across the entire menstrual cycle. Expression of PR-A was similar to that of PR-B, with reduced expression in the basalis stroma, and inner and outer myometrium in the adenomyotic samples. The pattern of ER-β, PR-A, and PR-B expression was similar in the endometrial basalis and adenomyotic foci.

CONCLUSION(S)

These data suggest ER-β expression and the lack of PR expression are related to the development and/or progression of adenomyosis and might explain the poor response of adenomyosis-associated menstrual symptoms to progestational agents.

Neonatal administration of tamoxifen causes disruption of myometrial development but not adenomyosis in the C57/BL6J mouse

We previously demonstrated that in the CD-1 mouse, which exhibits a high incidence of age-related adenomyosis, neonatal exposure to tamoxifen induced premature uterine adenomyosis and was associated with abnormal development particularly of the inner myometrium. In the present study, we examined the effect of neonatal tamoxifen administration upon uterine development in the C57/BL6J mouse strain that is not known to develop uterine adenomyosis. Female C57/BL6J pups (n=20) were treated with oral tamoxifen (1 mg/kg) from age 1 to 5 days. Uteri from control and treated mice were obtained on days 5, 10, 15 and 42 of age. We examined sections histologically using image analysis and immunohistochemistry for α-smooth muscle actin (ACTA2, α-SMA), desmin, vimentin, laminin, fibronectin and oestrogen receptor-α (ESR1). Following tamoxifen exposure, all uteri showed inner myometrium thinning, lack of continuity, disorganisation and bundling. However, adenomyosis was not seen in any uterus. ACTA2 immunostaining was less in the circular muscle layer of treated mice. The temporal pattern of desmin immunostaining found in control mice was absent in tamoxifen-treated mice. There was no difference in the localisation of laminin or fibronectin between control and tamoxifen-treated groups. However, laminin immunostaining was reduced in the circular muscle layer of treated mice. Vimentin could not be detected in either group. In conclusion, our results demonstrate that the development of the inner myometrium is particularly sensitive to oestrogen antagonism, and is affected by steroid receptor modulation. Although tamoxifen induces inner myometrial changes including that of ACTA2, desmin, ESR1 and laminin expression in C57/BL6J neonatal mice similar to those induced in CD-1 mice, C57/BL6J mice did not develop premature adenomyosis. Thus, disruption of the development and differentiation of the inner myometrium cannot alone explain the development of tamoxifen-associated adenomyosis, and this must be dependent upon its interaction with strain-dependent factors.

Enhanced invasion of stromal cells from adenomyosis in a three-dimensional coculture model is augmented by the presence of myocytes from affected uteri

OBJECTIVE

To compare endometrial stromal cell invasion from women with and without adenomyosis and the effect of myometrial cells using a three-dimensional coculture.

DESIGN

Case-controlled blinded comparison.

SETTING

University department.

PATIENT(S)

Premenopausal women with and without uterine adenomyosis.

INTERVENTION(S)

Human endometrial stromal and myometrial cells were grown in a three-dimensional coculture with crossover between cells from uteri with and without adenomyosis. Surface-enhanced laser desorption/ionization-time of flight-mass spectrometry proteomic analysis was performed on culture supernatants.

MAIN OUTCOME MEASURE(S)

Depth of stromal cell invasion into collagen matrix and protein expression profiles.

RESULT(S)

The depth of invasion for adenomyosis stromal cells (AS) was statistically significantly higher than controls (CS) whether grown on plain collagen, control muscle (CM), or adenomyosis muscle (AM). Coculture with AM enhanced invasion of both CS and AS. Enhanced invasion by AS was more marked in cocultures with AM than CM. Proteomic analysis identified differences that may account for the invasiveness and also many similarities between secretory products related to the disease status.

CONCLUSION(S)

Enhanced stromal invasion in adenomyosis is influenced by the myometrium in the in vitro coculture model. This suggests that adenomyosis may be a disease of both the endometrial stroma and myometrium.