Accurate Control of 17β-Estradiol Long-Term Release Increases Reliability and Reproducibility of Preclinical Animal Studies

Investigating the Role of 17-Beta Estradiol in the Regulation of the Unfolded Protein Response (UPR) in Pancreatic Beta Cells

Diabetes mellitus is clinically defined by chronic hyperglycemia. Sex differences in the presentation and outcome of diabetes exist with premenopausal women having a reduced risk of developing diabetes, relative to men, or women after menopause. Accumulating evidence shows a protective role of estrogens, specifically 17-beta estradiol, in the maintenance of pancreatic beta cell health; however, the mechanisms underlying this protection are still unknown. To elucidate these potential mechanisms, we used a pancreatic beta cell line (BTC6) and a mouse model of hyperglycemia-induced atherosclerosis, the ApoE-/-:Ins2+/Akita mouse, exhibiting sexual dimorphism in glucose regulation. In this study we hypothesize that 17-beta estradiol protects pancreatic beta cells by modulating the unfolded protein response (UPR) in response to endoplasmic reticulum (ER) stress. We observed that ovariectomized female and male ApoE-/-:Ins2+/Akita mice show significantly increased expression of apoptotic UPR markers. Sham operated female and ovariectomized female ApoE-/-:Ins2+/Akita mice supplemented with exogenous 17-beta estradiol increased the expression of adaptive UPR markers compared to non-supplemented ovariectomized female ApoE-/-:Ins2+/Akita mice. These findings were consistent to what was observed in cultured BTC6 cells, suggesting that 17-beta estradiol may protect pancreatic beta cells by repressing the apoptotic UPR and enhancing the adaptive UPR activation in response to pancreatic ER stress.

Estrogen alleviates acute and chronic itch in mice

Itching is associated with various skin diseases, including atopic dermatitis and allergic dermatitis, and leads to repeated scratching behavior and unpleasant sensation. Although clinical and laboratory research data have shown that estrogen is involved in regulating itch, the molecular and cellular basis of estrogen in itch sensation remains elusive. In the present study, it was found that estrogen-treated mice exhibited reduced scratching bouts when challenged with histamine, chloroquine, the proteinase-activated receptor-2 activating peptide SLIGRL-NH2 (SLIGRL), compound 48/80, and 5-hydroxytryptamine when compared with mice in the placebo group. Moreover, estrogen also suppressed scratching bouts in the mouse model of chronic itch induced by acetone-ether-water treatment. Notably, consistent with the behavioral tests, the present RNA-seq analysis showed that estrogen treatment caused significantly reduced expression levels of itch-related molecules such as Mas-related G-protein coupled receptor member A3, neuromedin B and natriuretic polypeptide b. In addition, estradiol attenuated histamine-induced and chloroquine-induced calcium influx in dorsal root ganglion neurons. Collectively, the data of the present study suggested that estrogen modulates the expression of itch-related molecules and suppresses both acute and chronic itch in mice.

Augmenting Skeletal Muscle Estrogen Does not Prevent or Rescue Obesity-linked Metabolic Impairments in Female Mice

AIMS

We developed a novel mouse model with increased skeletal muscle estrogen content via inducible, skeletal-muscle-specific aromatase overexpression (SkM-Arom↑). We proposed to examine the effect that increased skeletal muscle estrogen both in gonadally intact and ovariectomized (OVX) female mice has on preventing or rescuing high-fat diet (HFD)-induced obesity.

METHODS

In the prevention experiment, gonadally intact and OVX SkM-Arom↑ mice and littermate controls were fed a low-fat diet (LFD) or HFD for 13 weeks. SkM-Arom↑ was induced at the initiation of dietary treatment. In the intervention experiment, gonadally intact and OVX SkM-Arom↑ mice and littermate controls were fed an HFD for 14 weeks before induction of SkM-Arom↑ for 6 weeks. Glucose tolerance, insulin action, adipose tissue inflammation, and body composition were assessed. Liquid chromatography-mass spectrometry was used to determine circulating and skeletal muscle steroid content.

RESULTS

SkM-Arom↑ significantly increased skeletal muscle 17β-estradiol (E2) and estrone (E1) in both experiments. Interestingly, this resulted in leakage of estrogens into circulation, producing a physiologically relevant E2 concentration. Consequently, bone mineral density (BMD) was enhanced and adipose tissue inflammation was reduced in the prevention experiment only. However, no benefits were seen with respect to changes in adiposity or metabolic outcomes.

CONCLUSION

We show that increasing skeletal muscle estrogen content does not provide a metabolic benefit in gonadally intact and OVX female mice in the setting of obesity. However, a chronic physiological concentration of circulating E2 can improve BMD and reduce adipose tissue inflammation independently of a metabolic benefit or changes in adiposity.

HPV infection alters vaginal microbiome through down-regulating host mucosal innate peptides used by Lactobacilli as amino acid sources

Despite the high prevalence of both cervico-vaginal human papillomavirus (HPV) infection and bacterial vaginosis (BV) worldwide, their causal relationship remains unclear. While BV has been presumed to be a risk factor for HPV acquisition and related carcinogenesis for a long time, here, supported by both a large retrospective follow-up study (n = 6,085) and extensive in vivo data using the K14-HPV16 transgenic mouse model, we report a novel blueprint in which the opposite association also exists. Mechanistically, by interacting with several core members (NEMO, CK1 and β-TrCP) of both NF-κB and Wnt/β-catenin signaling pathways, we show that HPV E7 oncoprotein greatly inhibits host defense peptide expression. Physiologically secreted by the squamous mucosa lining the lower female genital tract, we demonstrate that some of these latter are fundamental factors governing host-microbial interactions. More specifically, several innate molecules down-regulated in case of HPV infection are hydrolyzed, internalized and used by the predominant Lactobacillus species as amino acid source sustaining their growth/survival. Collectively, this study reveals a new viral immune evasion strategy which, by its persistent/negative impact on lactic acid bacteria, ultimately causes the dysbiosis of vaginal microbiota.

A new clinically-relevant rat model of letrozole-induced chronic nociceptive disorders

Among postmenopausal women with estrogen receptor-positive breast cancer, more than 80% receive hormone therapy including aromatase inhibitors (AIs). Half of them develop chronic arthralgia - characterized by symmetric articular pain, carpal tunnel syndrome, morning stiffness, myalgia and a decrease in grip strength - which is associated with treatment discontinuation. Only a few animal studies have linked AI treatment to nociception, and none to arthralgia. Thus, we developed a new chronic AI-induced nociceptive disorder model mimicking clinical symptoms induced by AIs, using subcutaneous letrozole pellets in ovariectomized (OVX) rats. Following plasma letrozole dosage at the end of the experiment (day 73), only rats with at least 90 ng/ml of letrozole were considered significantly exposed to letrozole (OVX + high LTZ group), whereas treated animals with less than 90 ng/ml were pooled in the OVX + low LTZ group. Chronic nociceptive disorder set in rapidly and was maintained for more than 70 days in the OVX + high LTZ group. Furthermore, OVX + high LTZ rats saw no alteration in locomotion, myalgia or experimental anxiety during this period. Bone parameters of the femora were significantly altered in all OVX rats compared to Sham+vehicle pellet. A mechanistic analysis focused on TRPA1, receptor suspected to mediate AI-evoked pain, and showed no modification in its expression in the DRG. This new long-lasting chronic rat model, efficiently reproduces the symptoms of AI-induced nociceptive disorder affecting patients' daily activities and quality-of-life. It should help to study the pathophysiology of this disorder and to promote the development of new therapeutic strategies.

Estetrol Combined to Progestogen for Menopause or Contraception Indication Is Neutral on Breast Cancer

Simple Summary

Hormonal treatments, especially those used to treat menopause symptoms are known to increase breast cancer risk. It is thus necessary to identify new formulations with a better benefit/risk profile. The aim of this translational study was to evaluate the breast cancer risk associated with a combination of a natural estrogen named estetrol, with progestogens such as natural progesterone and drospirenone. Since the assessment of breast cancer risk in patients during drug development is not possible given the requirement of long-term studies in large populations, this study provides new evidence that a therapeutic dose of estetrol for menopause treatment or contraception, combined with progesterone or drospirenone, may provide a better benefit/risk profile toward breast cancer risk compared to the hormonal treatments currently available for patients.

Abstract

Given the unequivocal benefits of menopause hormone therapies (MHT) and combined oral contraceptives (COC), there is a clinical need for new formulations devoid of any risk of breast cancer promotion. Accumulating data from preclinical and clinical studies support that estetrol (E4) is a promising natural estrogen for MHT and COC. Nevertheless, we report here that E4 remains active on the endometrium, even under a dose that is neutral on breast cancer growth and lung metastasis dissemination. This implies that a progestogen should be combined with E4 to protect the endometrium of non-hysterectomized women from hyperplasia and cancer. Through in vivo observations and transcriptomic analyses, our work provides evidence that combining a progestogen to E4 is neutral on breast cancer growth and dissemination, with very limited transcriptional impact. The assessment of breast cancer risk in patients during the development of new MHT or COC is not possible given the requirement of long-term studies in large populations. This translational preclinical research provides new evidence that a therapeutic dose of E4 for MHT or COC, combined with progesterone or drospirenone, may provide a better benefit/risk profile towards breast cancer risk compared to hormonal treatments currently available for patients.

Protective effects of Avena sativa against oxidative stress-induced kidney damage resulting from an estrogen deficiency in ovariectomized Swiss mice model

The aim of this study was to evaluate the antioxidant capacity of Avena sativa and to confirm its protective effects on estrogen deficiency in ovariectomized mice (OVX) model. Animals were treated during 21 and 60 days as follows: negative control, positive control treated with oat, ovariectomized, and ovariectomized receiving hormonal or oat treatments, respectively. 21 days post-surgery, our results showed that ovariectomy increases weight gain and urea level in plasma. After 60 days of treatment, OVX showed a gain in weight, high increases in relative kidney weight, plasmatic creatinine, glutathione peroxidase (GPX) activity, and protein oxidation as shown by elevated protein carbonyl (PCO) and advanced oxidation protein products (AOPP) levels. On the other side, a decrease was detected in catalase activity. Meanwhile, no significant changes in urea level, lipid peroxidation, SOD and GSH activity were detected. Conversely, supplementation with oat reduced weight gain, as well as oxidative stress and oxidation protein in the kidney of OVX mice. PRACTICAL APPLICATIONS: In our study, we removed the two ovaries of adult female mice in order to eliminate the essential source of steroid hormones. Deficiency in these sexual hormones, especially estrogen, leads to several physiological and morphological disturbances that are found in post-menopausal women. The gain in weight and oxidative kidney damages were the main health problems detected in ovariectomized animals. This work explored for the first time the use of oat grains as a safe natural remedy to treat all previous health problems and to avoid carcinogenic effects of the menopausal hormone therapy. Owing to its health benefits, this cereal species has recently gained attention as an important source of antioxidants and fibers. Thanks to these two components, it can be able to restore all indicated disturbances. Therefore, this cereal can be very useful in the prevention of obesity and kidney oxidative damage occurring during menopause.

Chronic Testosterone Deprivation Sensitizes the Middle-Aged Rat Brain to Damaging Effects of Testosterone Replacement

INTRODUCTION

An increasing number of middle-aged men are being screened for low testosterone levels and the number of prescriptions for various forms of testosterone replacement therapy (TRT) has increased dramatically over the last 10 years. However, the safety of TRT has come into question with some studies suggesting increased morbidity and mortality.

OBJECTIVE

Because the benefits of estrogen replacement in postmenopausal women and ovariectomized rodents are lost if there is an extended delay between estrogen loss and replacement, we hypothesized that TRT may also be sensitive to delayed replacement.

METHODS

We compared the effects of testosterone replacement after short-term (2 weeks) and long-term testosterone deprivation (LTTD; 10 weeks) in middle-aged male rats on cerebral ischemia, oxidative stress, and cognitive function. We hypothesized that LTTD would increase oxidative stress levels and abrogate the beneficial effects of TRT.

RESULTS

Hypogonadism itself and TRT after short-term castration did not affect stroke outcome compared to intact rats. However, after long-term hypogonadism in middle-aged male Fischer 344 rats, TRT exacerbated the detrimental behavioral effects of experimental focal cerebral ischemia, whereas this detrimental effect was prevented by administration of the free-radical scavenger tempol, suggesting that TRT exacerbates oxidative stress. In contrast, TRT improved cognitive performance in non-stroked rats regardless of the length of hypogonadism. In the Morris water maze, peripheral oxidative stress was highly associated with decreased cognitive ability.

CONCLUSIONS

Taken together, these data suggest that TRT after long-term hypogonadism can exacerbate functional recovery after focal cerebral ischemia, but in the absence of injury can enhance cognition. Both of these effects are modulated by oxidative stress levels.

Skeletal impact of 17β-estradiol in T cell-deficient mice: age-dependent bone effects and osteosarcoma formation

Estrogen (E₂)-dependent ER+ breast cancer, the most common breast cancer subtype, is also the most likely to metastasize to bone and form osteolytic lesions. However, ER+ breast cancer bone metastasis human xenograft models in nude mice are rarely studied due to complexities associated with distinguishing possible tumoral vs. bone microenvironmental effects of E₂. To address this knowledge gap, we systematically examined bone effects of E₂ in developing young (4-week-old) vs. skeletally mature (15-week-old) female Foxn1^nu nude mice supplemented with commercial 60-day slow-release E₂ pellets and doses commonly used for ER+ xenograft models. E₂ pellets (0.05-0.72 mg) were implanted subcutaneously and longitudinal changes in hind limb bones (vs. age-matched controls) were determined over 6 weeks by dual-energy X-ray absorptiometry (DXA), microCT, radiographic imaging, and histology, concurrent with assessment of serum levels of E₂ and bone turnover markers. All E₂ doses tested induced significant and identical increases in bone density (BMD) and volume (BV/TV) in 4-week-old mice with high bone turnover, increasing bone mineral content (BMC) while suppressing increases in bone area (BA). E₂ supplementation, which caused dose-dependent changes in circulating E₂ that were not sustained, also led to more modest increases in BMD and BV/TV in skeletally mature 15-week-old mice. Notably, E₂-supplementation induced osteolytic osteosarcomas in a subset of mice independent of age. These results demonstrate that bone effects of E₂ supplementation should be accounted for when assessing ER+ human xenograft bone metastases models.

Sex-dependent effects of estrogen pellets in human liver cancer xenograft models

Liver cancer shows noticeable differences in the incidence rate and mortality between genders. To investigate the estrogen effect on tumor progression in liver cancer, we developed a xenograft model using estrogen pellets. SK-Hep1 cells (human male liver carcinoma) were inoculated into male or female nude mice. Subsequently, estrogen pellets were subcutaneously implanted into these xenograft models. Interestingly, the marked adverse effect of estrogen pellets (0.5 mg/21 days) were observed in the male-derived xenograft model, with increased ulcerative dermatitis in male mice than in female mice. Additionally, necrosis was observed in male mice with SK-Hep1-derived tumors. However, the estrogen pellet (0.5 mg/60 days) did not exhibit these adverse effects. Tumor growth in female mice was significantly suppressed by estrogen (0.5 mg/60 days). Tumor growth was also suppressed in male mice implanted with estrogen (0.5 mg/60 days), but the suppression was not significant. We found that estrogen-induced skin damage was more severe in male mice than female mice. The tumor suppression of estrogen was effective in female mice compared to male mice bearing liver cancer. The results suggest that the sex difference affects estrogen activity and thus should be considered in the preclinical assessment.

Dynamic interactions between the extracellular matrix and estrogen activity in progression of ER+ breast cancer

Metastatic, anti-estrogen resistant estrogen receptor α positive (ER+) breast cancer is the leading cause of breast cancer deaths in U.S. women. While studies have demonstrated the importance of the stromal tumor microenvironment in cancer progression and therapeutic responses, effects on the responses of ER+ cancers to estrogen and anti-estrogens are poorly understood, particularly in the complex in vivo environment. In this study, we used an estrogen responsive syngeneic mouse model to interrogate how a COL1A1-enriched fibrotic ECM modulates integrated hormonal responses in cancer progression. We orthotopically transplanted the ER+ TC11 cell line into wild-type (WT) or collagen-dense (Col1a1^tm1Jae/+, mCol1a1) syngeneic FVB/N female mice. Once tumors were established, recipients were supplemented with 17β-estradiol (E2), tamoxifen, or left untreated. Although the dense/stiff environment in mCol1a1 recipients did not alter the rate of E2-induced proliferation of the primary tumor, it fostered the agonist activity of tamoxifen to increase proliferation and AP-1 activity. Manipulation of estrogen activity did not alter the incidence of lung lesions in either WT or mCol1a1 hosts. However, the mCol1a1 environment enabled tamoxifen-stimulated growth of pulmonary metastases and further fueled estrogen-driven growth. Moreover, E2 remodeled peritumoral ECM architecture in WT animals, modifying alignment of collagen fibers and altering synthesis of ECM components associated with increased alignment and stiffness, and increasing FN1 and POSTN expression in the pulmonary metastatic niche. These studies demonstrate dynamic interactions between ECM properties and estrogen activity in progression of ER+ breast cancer, and support the need for therapeutics that target both ER and the tumor microenvironment.

Lymph/angiogenesis contributes to sex differences in lung cancer through oestrogen receptor alpha signalling

Oestrogen signalling pathways are emerging targets for lung cancer therapy. Unravelling the contribution of oestrogens in lung cancer development is a pre-requisite to support the development of sex-based treatments and identify patients who could potentially benefit from anti-oestrogen treatments. In this study, we highlight the contribution of lymphatic and blood endothelia in the sex-dependent modulation of lung cancer. The orthotopic graft of syngeneic lung cancer cells into immunocompetent mice showed that lung tumours grow faster in female mice than in males. Moreover, oestradiol (E2) promoted tumour development, increased lymph/angiogenesis and VEGFA and bFGF levels in lung tumours of females through an oestrogen receptor (ER) alpha-dependent pathway. Furthermore, while treatment with ERb antagonist was inefficient, ERa antagonist (MPP) and tamoxifen decreased lung tumour volumes, altered blood and lymphatic vasculature and reduced VEGFA and bFGF levels in females, but not in males. Finally, the quantification of lymphatic and blood vasculature of lung adenocarcinoma biopsies from patients aged between 35 and 55 years revealed more extensive lymphangiogenesis and angiogenesis in tumour samples issued from women than from men. In conclusion, our findings highlight an E2/ERa-dependent modulation of lymphatic and blood vascular components of lung tumour microenvironment. Our study has potential clinical implication in a personalised medicine perspective by pointing to the importance of oestrogen status or supplementation on lung cancer development that should be considered to adapt therapeutic strategies.

The challenges of modeling hormone receptor-positive breast cancer in mice

Estrogen receptor-positive (ER+) tumors account for 70-80% of all breast cancer (BC) cases and are characterized by estrogen dependency for their growth. Endocrine therapies using estrogen receptor antagonists or aromatase inhibitors represent a key component of the standard of care for these tumors. The occurrence of de novo or acquired resistance to estrogen withdrawal represents an important clinical problem, impacting on patient survival. In addition, despite an initially favorable outcome, a part of ER+ BC patients present with disease recurrence locally or at distant sites years or even decades after apparent remission. In vivo models that closely mimic human disease are urgently needed to study the biology of these tumors, investigate the molecular mechanisms underlying endocrine resistance and identify patients at risk of recurrence. Despite the similarities in the overall hormonal regulation of mammary gland development between mice and humans, the majority of the mammary carcinomas occurring in genetically engineered mouse models (GEMMs) are ER negative and most xenograft models are based on few ER+ cancer cell lines. We recently showed that the microenvironment is critical for ER+ cancer cells and discuss in this review the potential of intraductal xenograft model for basic and preclinical research.