Apelin receptor modulation mitigates letrozole-induced polycystic ovarian pathogenesis in mice

AIMS

Polycystic ovarian syndrome (PCOS) is one of the most common (about 5-20%) reproductive disorders in women of reproductive age; it is characterized by polycystic ovaries, hyperandrogenism, and oligo/ anovulation. The levels and expression of ovarian adipokines are deregulated in the PCOS. Apelin is an adipokine that acts through its receptor (APJ) and is known to express in the various tissues including the ovary. It has also been suggested that apelin and APJ could be targeted as therapeutic adjuncts for the management of PCOS. However, no study has been conducted on the management of PCOS by targeting the apelin system. Thus, we aimed to evaluate its impact on combating PCOS-associated ovarian pathogenesis.

METHODS

The current work employed a letrozole-induced-hyperandrogenism PCOS-like mice model to investigate the effects of apelin13 and APJ, antagonist ML221. The PCOS model was induced by oral administration of letrozole (1 mg/kg) for 21 days. A total of four experimental groups were made, control, PCOS control, PCOS + aplein13, and PCOS + ML221. The treatment of apelin13 and ML221 was given from day 22 for two weeks.

KEY FINDINGS

The letrozole-induced PCOS-like features such as hyperandrogenism, cystic follicle, decreased corpus luteum, elevated levels of LH/FSH ratio, and up-regulation of ovarian AR expression were ameliorated by apelin13 and ML221 treatment. However, the PCOS-augmented oxidative stress and apoptosis were suppressed by apelin 13 treatments only. ML221 treatment still showed elevated oxidative stress and stimulated apoptosis as reflected by decreased antioxidant enzymes and increased active caspase3 and Bax expression. The expression of ERs was elevated in all groups except control. Furthermore, the PCOS model showed elevated expression of APJ and apelin13 treatment down-regulated its own receptor. Overall, observing the ovarian histology, corpus luteum formation, and decreased androgen levels by both apelin13 and ML221 showed ameliorative effects on the cystic ovary.

SIGNIFICANCE

Despite the similar morphological observation of ovarian histology, apelin13 and ML221 exhibited opposite effects on oxidative stress and apoptosis. Therefore, apelin13 (which down-regulates APJ) and ML221 (an APJ antagonist) may have suppressed APJ signalling, which would account for our findings on the mitigation of polycystic ovarian syndrome. In conclusion, both apelin13 and ML221 mediated mitigation have different mechanisms, which need further investigation.

Letrozole cotreatment progestin-primed ovarian stimulation in women undergoing controlled ovarian stimulation for in vitro fertilization

AIM

To investigate the impact of letrozole cotreatment progestin-primed ovarian stimulation (PPOS) (Le PPOS) in controlled ovarian stimulation (COS) and the pregnancy outcomes in frozen-thawed embryo transfer cycles.

METHODS

This retrospective cohort study included women who underwent in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI). A total of 2575 cycles were included (1675 in the Le PPOS group and 900 in the PPOS group). The primary outcome was the clinical pregnancy rates. The secondary outcome was the live birth rates.

RESULTS

In this study, propensity score matching (PSM) was performed to create a perfect match of 379 patients in each group. After matching, the numbers of oocytes retrieved, mature oocytes, fertilization, and clinical pregnancy rates were more favorable in the Le PPOS group than in the PPOS group (all p < 0.05). The multivariable analysis showed that the clinical pregnancy rate was higher in the Le PPOS than in the PPOS group (odds ratio = 1.46, 95% confidence interval: 1.05-2.04, p = 0.024) after adjusting for potentially confounding factors (age, anti-Müllerian hormone levels, antral follicular count, the type of embryo transferred, number of transferred embryos, body mass index, and follicular stimulating hormone and estradiol levels on starting day).

CONCLUSIONS

This retrospective study with a limited sample size suggests that the Le PPOS protocol might be an alternative to the PPOS protocol in women undergoing COS and could lead to better pregnancy outcomes. The results should be confirmed using a formal randomized controlled trial.

The effect of adipose-derived mesenchymal stem cell transplantation on ovarian mitochondrial dysfunction in letrozole-induced polycystic ovary syndrome in rats: the role of PI3K-AKT signaling pathway

OBJECTIVE

The present study aimed to elucidate how mesenchymal stem cells (MSCs) application could efficiently attenuate pathological changes of letrozole-induced poly cystic ovary syndrome (PCOS) by modulating mitochondrial dynamic via PI3K-AKT pathway.

METHODS

Thirty-two female rats were randomly divided into four experimental groups: Sham, PCOS, PCOS + MSCs, and PCOS + MSCs + LY294002. The Sham group received 0.5% w/v carboxymethyl cellulose (CMC); the PCOS group received letrozole (1 mg/kg, daily) in 0.5% CMC for 21 days. Animals in the PCOS + MSCs group received 1 × 106 MSCs/rat (i.p,) on the 22th day of the study. In the PCOS + MSCs + LY294002 group, rats received LY294002 (PI3K-AKT inhibitor) 40 min before MSC transplantation. Mitochondrial dynamic gene expression, mitochondrial membrane potential (MMP), citrate synthase (CS) activity, oxidative stress, inflammation, ovarian histological parameters, serum hormone levels, homeostatic model assessment for insulin resistance (HOMA-IR), insulin and glucose concentrations, p-PI3K and p-AKT protein levels were evaluated at the end of the experiment.

RESULTS

PCOS rats showed a significant disruption of mitochondrial dynamics and histological changes, lower MMP, CS, ovary super oxide dismutase (SOD) and estrogen level. They also had a notable rise in insulin and glucose concentrations, HOMA-IR, testosterone level, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels, ovarian malondialdehyde (MDA) content as well as a notable decrease in p-PI3K and p-AKT protein levels compared to the Sham group. In the PCOS + MSCs group, the transplantation of MSCs could improve the above parameters. Administration of LY294002 (PI3K-AKT pathway inhibitor) deteriorated mitochondrial dynamic markers, oxidative stress status, inflammation markers, hormonal levels, glucose, and insulin levels and follicular development compared to the PCOS + MSCs group.

CONCLUSIONS

This study demonstrated that the protective effects of MSC transplantation in regulating mitochondrial dynamics, promoting mitochondrial biogenesis, competing with redox status and inflammation response were mainly mediated through the PI3K-AKT pathway in the PCOS model.

Effect of Aromatase Inhibitor Letrozole on the Placenta of Adult Albino Rats: A Histopathological, Immunohistochemical, and Biochemical Study

Background

Letrozole, an aromatase inhibitor, has recently been introduced as the preferred treatment option for ectopic pregnancy. To date, no study has investigated the effect of letrozole alone on placental tissue. The present study aimed to evaluate the effect of different doses of letrozole on the placenta of rats and to clarify the underlying mechanism.

Methods

Sixty pregnant female rats were equally divided into three groups, namely the control group (GI), low-dose (0.5 mg/Kg/day) letrozole group (GII), which is equivalent to the human daily dose (HED) of 5 mg, and high-dose (1 mg/Kg/day) letrozole group (GIII), equivalent to the HED of 10 mg. Letrozole was administered by oral gavage daily from day 6 to 16 of gestation. Data were analyzed using a one-way analysis of variance followed by Tukey's post hoc test and Chi square test. P<0.05 was considered statistically significant.

Results

Compared to the GI and GII groups, high-dose letrozole significantly increased embryonic mortality with a high post-implantation loss rate (P<0.001) and significantly reduced the number of viable fetuses (P<0.001) and placental weight (P<0.001) of pregnant rats. Moreover, it significantly reduced placental estrogen receptor (ER) and progesterone receptor (PR) (P<0.001) and the expression of vascular endothelial growth factor (P<0.001), while increasing the apoptotic index of cleaved caspase-3 (P<0.001).

Conclusion

Letrozole inhibited the expression of ER and PR in rat placenta. It interrupted stimulatory vascular signals causing significant apoptosis and placental vascular dysfunction. Letrozole in an equivalent human daily dose of 10 mg caused a high post-implantation loss rate without imposing severe side effects.

Design and Pharmacophore Study of Triazole Analogues as Aromatase Inhibitors

BACKGROUND

In current scenario breast cancer measured as one of the dangerous health issues. An effective therapeutic class of drug known as aromatase inhibitors (AIs) is dominant against estrogen receptorpositive breast cancer. However, there is an urgent need to create target-specific AIs with better anti-breast cancer profiles due to the increased toxicity and adverse effects related to currently existing anti-breast cancer drugs.

OBJECTIVES

In the present study, we have designed of 100 novel tiazole analogues as aromatase inhibitors their pharmacophoric features were explored.

METHOD

Molecular docking was applied to a series of 4-substituted-1, 2, 3-triazoles containing letrozole for their aromatase inhibitory effects. The aromatase inhibitory activity of the compound in a series varies in the range of (IC50 = 0.008-31.26 μM). A hydrogen atom positioned at R1 of the triazole ring in compound (01) was responsible for the most potent compound (IC50 = 0.008 μM) in the series of 28 compounds as compared to letrozole. The self-organizing molecular field study was used to assess the molecular characteristics and biological activities of the compounds. The four models were developed using PLS and MLR methods. The PLS method was good for statistical analysis. The letrozole scaffold-based 100 compounds were designed by selecting an effective pharmacophore responsible for aromatase inhibitory activity. The designed compound was placed on the previous model as a test set, and its IC50 values were calculated.

RESULT

Hydrogen bonds were established between the potent molecule (01) and the essential residues Met 374 and Arg 115, which were responsible for the aromatase-inhibiting action. Cross-validated q2 (0.6349) & noncross- validated r2 (0.7163) were discovered in the statistical findings as having reliable predictive power. Among 100 designed compounds, seven compounds showed good aromatase inhibitory activities.

CONCLUSION

The additional final SOMFA model created for the interactions between the aromatase and the triazole inhibitors may be helpful for future modification and enhancement of the inhibitors of this crucial enzyme.

Effects of dietary aromatase inhibitors on masculinization of rosy barb (Pethia conchonius): Evidence from growth, coloration and gonado-physiological changes

The objective of this study was to reveal the growth, colouration and gonado-physiological changes due to the exogenous aromatase inhibitor (AIs) in an ornamental fish. 17α-methyltestosterone (MT) and letrozole (LET) were used as potential AIs. The AI were supplemented with a gel-based feed (LET: 50, 100, 150 and MT: 12.5, 25, 37.5 mg/kg feed) in Rosy barb, Pethia conchonius fry. The fishes were reared in a 45-L glass tank using AI treated gel-based feed for 3 months. Growth in AI-based diets was reduced but the reduction was minimal compared to the control. At 25 mg/kg feed of 17 MT, the highest male proportion (84.72% 6.05%) was recorded, which was significantly higher (P≤0.05) than other groups. L*, a*, and b* values showed that 17α-MT-fed groups had brighter coloration (P≤0.05). Histological sections showed that LET-17α-MT suppressed ovarian development, causing atretic oocytes. Testicular development was unaffected. 25 mg/kg-treated feed increased SOD, CAT, GST, and GPX. The AI (MT) at 25 mg/kg gel-based feed could therefore be utilised for musculinization without impacting growth, colour, and antioxidant activity of rosy barb, which serves the entire male population in the ornamental fish sector.

Effect of the ketogenic diet on gut microbiome composition and metabolomics in polycystic ovarian syndrome rats induced by letrozole and a high-fat diet

OBJECTIVES

The ketogenic diet (KD) is recommended to improve polycystic ovary syndrome (PCOS); however, its mechanisms of action are unclear. We aimed to study the effects and mechanisms of action of the KD on the gut microbiome and metabolites in PCOS rats and determine whether the sex hormone regulatory effects are related to modulations of the gut microbiota and metabolites.

METHODS

PCOS was induced with a high-fat diet and letrozole in the rats. A KD was fed to rats for 8 wk, serum samples were collected for biochemical analysis, and the rats' fecal samples were subjected to 16S ribosomal RNA sequencing and metabolomic analysis.

RESULTS

Feeding with a KD for 8 wk suppressed body weight gain, decreased luteinizing hormone and androgen levels, and improved insulin levels. Furthermore, the KD reversed the dysregulation of the gut microbiota in PCOS rats by adjusting the ratio of firmicutes and bacteroidetes. Also, the KD was involved in hormonal metabolic pathways by reducing the levels of some metabolites (such as testosterone and 7α-hydroxytestosterone) that are closely related to gut microbes.

CONCLUSIONS

The KD improved the clinical phenotype and insulin resistance in PCOS rats and altered the composition of the gut microbiome and metabolites, which were associated with androgen metabolism, representing a potential mechanism for mediating the effects of the KD on sex hormone metabolism in PCOS. However, our study found contradictory effects of KD on the gut microbiome in PCOS, which need further research.

Novel studies on Isolation, purification and characterization of dibenzonitro compound from Glycosmis pentaphylla (Retz.) DC. and effect in downregulating neuronal cancers

To isolate Letrozole from Glycosmis pentaphylla (Retz.) DC. and to determine its effect on regulating the proliferation, cell cycle distribution, apoptosis and key mechanisms in human neuroblastoma cell lines. Letrozole was isolated through column chromatographic technique and its effect was checked on human neuroblastoma cell lines, IMR 32. The effects of Letrozole on cell viability were measured by MTT assay, and the cell cycle distribution was determined by flow cytometry. The expression changes in mRNA of proliferating cell nuclear antigen (PCNA), cyclin D1 and Bcl-xL were taken from real-time PCR analysis and the protein levels were detected by Western blotting. The results of the present study showed that Letrozole, isolated from leaves of G. pentaphylla could cause significant inhibitory effect on proliferation of IMR 32 cells in a dose dependent manner. Cell arrest was obtained at S phase with the treatment of Letrozole. Apart from this, the expression of PCNA, cyclin D1 and Bcl-xL were decreased both at mRNA and protein levels for the same treatment. Letrozole can inhibit proliferation, induce cell arrest and cause apoptosis in IMR 32 cell lines. The decreased expression of PCNA, cyclin D1 and Bcl-xL induced by Letrozole contributes to the above effects in vitro. This is the first report on the isolation of Letrozole from G. pentaphylla.

Aromatase Inhibition and Electroconvulsive Seizures in Adolescent Rats: Antidepressant and Long-Term Cognitive Sex Differences

BACKGROUND

We recently showed sex differences in the antidepressant-like potential of electroconvulsive seizures (ECS) in adolescent rats; whereas it worked for male rats, it was inefficacious in females. Because sex steroids might be important modulators of these sex disparities, we evaluated the role of estrogens in the differential response induced by adolescent ECS. Moreover, given the literature suggesting certain cognitive sequelae from ECS exposure, we aimed at evaluating its long-term safety profile in adulthood.

METHODS

Adolescent Sprague-Dawley rats were pretreated with letrozole (1 mg/kg/day) or vehicle (1 mL/kg/day) for 8 days (i.p.) and treated during the last 5 days (3 hours later) with ECS (95 mA, 0.6 s, 100 Hz) or SHAM. Antidepressant-like responses were measured in the forced swim test, and long-term cognitive performance was assessed in the Barnes maze.

RESULTS

During adolescence, whereas ECS alone exerted an antidepressant-like response in male rats, its combination with letrozole permitted ECS to also induce efficacy in females. Moreover, adolescent ECS treatment improved cognitive performance in adulthood although exclusively in male rats.

CONCLUSIONS

Adolescent ECS demonstrated an antidepressant-like potential together with certain long-term beneficial cognitive effects but exclusively in male rats. For females, efficacy was restricted to a situation in which the biosynthesis of estrogens was reduced. Therefore, estrogens and/or testosterone levels play a crucial role in the sex disparities induced by ECS in Sprague-Dawley rats. Based on this study and on the literature supporting its safety, ECS should be encouraged for use in cases of treatment-resistant depression during adolescence, while adhering to sex-specific considerations.

The effect of letrozole overlapped with gonadotropin on IVF outcomes in women with DOR or aged over 40 years old with repeated cycles

BACKGROUND

Evaluating the efficacy of letrozole overlapped with gonadotropin-modified letrozole protocol (mLP) for diminished ovarian reserve (DOR) or advanced-age women with repeated cycles.

METHODS

This is a retrospectively registered, paired-match study including 243 women with DOR and 249 women aged over 40 years old who received in vitro fertilization (IVF) treatment. 123 women received stimulation with mLP (mLP group). GnRH agonist (GnRH-a) long, GnRH antagonist (GnRH-anta), and mild stimulation protocol were used as controls with 123 women in each group. We further analyzed 50 of 123 patients in the mLP group who have experienced more than one failed cycles with other ovarian stimulation protocols (non-mLP group). Clinical pregnancy rate (CPR), cumulative clinical pregnancy rate (CCPR), and live birth rate (LBR) were main outcomes.

RESULTS

The CPR in the mLP group (38.46%) was significantly higher than mild stimulation (17.11%), but not significantly different from GnRH-a long (26.13%) and GnRH-anta (29.17%) group. The CCPR showed an increasing trend in the mLP group (33.33%) although without significance when compared with controls. The CCRP of GnRH-a long, GnRH-anta, mild stimulation group were 21.68%, 29.03%, and 13.04%, respectively. In women with repeated cycles, mLP achieved the higher available embryo rate (P < 0.05), the top-quality embryo rate, the CPR (P < 0.001), and the LBR (P < 0.001). Further study showed a positive correlation between testosterone and the number of oocytes retrieved in the mLP group (r = 0.395, P < 0.01).

CONCLUSION

The mLP may be effective for aged or DOR women who have experienced previous cycle failure by improving the quality of embryos, the CPR, and the LBR. An increasing serum testosterone level may reflect follicular growth during ovarian stimulation.

Ferrozoles: Ferrocenyl derivatives of letrozole with dual effects as potent aromatase inhibitors and cytostatic agents

In the treatment of hormone-dependent cancers, aromatase inhibitors (AI) are receiving increased attention due to some undesirable effects such as the risk of endometrial cancer and thromboembolism of SERMs (selective estrogen receptor modulators). Letrozole is the most active AI with 99% aromatase inhibition. Unfortunately, this compound also exhibits some adverse effects such as hot flashes and fibromyalgias. Therefore, there is an urgent need to explore new types of AIs that retain the same-or even increased-antitumor ability. Inspired by the letrozole structure, a set of new derivatives has been synthesized that include a ferrocenyl moiety and different heterocycles. The derivative that contains a benzimidazole ring, namely compound 6, exhibits a higher aromatase inhibitory activity than letrozole and it also shows potent cytostatic behavior when compared to other well-established aromatase inhibitors, as demonstrated by dose-response, cell cycle, apoptosis and time course experiments. Furthermore, 6 promotes the inhibition of cell growth in both an aromatase-dependent and -independent fashion, as indicated by the study of A549 and MCF7 cell lines. Molecular docking and molecular dynamics calculations on the interaction of 6 or letrozole with the aromatase binding site revealed that the ferrocene moiety increases the van der Waals and hydrophobic interactions, thus resulting in an increase in binding affinity. Furthermore, the iron atom of the ferrocene fragment can form a metal-acceptor interaction with a propionate fragment, and this results in a stronger coupling with the heme group-a possibility that is consistent with the strong aromatase inhibition of 6.

Comprehensive Analysis of Gut Microbiota Alteration in the Patients and Animal Models with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a common disease of endocrine-metabolic disorder, and its etiology remains largely unknown. The gut microbiota is possibly involved in PCOS, while the association remains unclear. The comprehensive analysis combining gut microbiota with PCOS typical symptoms was performed to analyze the role of gut microbiota in PCOS in this study. The clinical patients and letrozole-induced animal models were determined on PCOS indexes and gut microbiota, and fecal microbiota transplantation (FMT) was conducted. Results indicated that the animal models displayed typical PCOS symptoms, including disordered estrous cycles, elevated testosterone levels, and ovarian morphological change; meanwhile, the symptoms were improved after FMT. Furthermore, the microbial diversity exhibited disordered, and the abundance of the genus Ruminococcus and Lactobacillus showed a consistent trend in PCOS rats and patients. The microbiota diversity and several key genera were restored subjected to FMT, and correlation analysis also supported relevant conclusions. Moreover, LEfSe analysis showed that Gemmiger, Flexispira, and Eubacterium were overrepresented in PCOS groups. Overall, the results indicate the involvement of gut microbiota in PCOS and its possible alleviation of endocrinal and reproductive dysfunctions through several special bacteria taxa, which can function as the biomarker or potential target for diagnosis and treatment. These results can provide the new insights for treatment and prevention strategies of PCOS.

Characterization of Early Gonadal Differentiation and Induction of Sex Reversal in the Rock Bream Oplegnathus fasciatus

Rock bream (Oplegnathus fasciatus) is a typical fish that has a unique multiple sex chromosome system (♀X1X1X2X2/♂X1X2Y). We examined the early gonadal development in rock bream via continuous histological observations of the gonads at 40-120 days post hatching (dph). The fish was identified as a typical gonochorist, and female gonads were found to differentiate earlier than male gonads. The ovarian cavity of the female was initially observed at 80 dph, whereas the efferent duct of the male was not observed until 100 dph. Immunofluorescence with the vasa-antibody revealed that germ cells were predominantly distributed around the ovarian cavity in females and on the edge of the gonad in males during the early stages of sex differentiation. Sex reversal was induced via the oral administration of letrozole (LTZ), 17α-methyltestosterone (MT), and 17β-estradiol (E2), respectively, during the labile period of gonadal development. LTZ and MT induced 100% masculinization of genotype-females, whereas E2 induced only 50-60% feminization of genotype-males. Such findings suggest that the fish retained high sexual plasticity despite the existence of the neo-Y chromosome. MT and E2 had negative effect on fish growth, whereas LTZ did not exert such side effect. LTZ and MT could accelerate gonadal development in sex-reversed genotype-males, whereas E2 inhibited gonadal development in genotype-females of rock bream. These findings provide a basis for further research on the mechanisms of sex determination and differentiation in fishes with X1X2Y sex chromosome system and provide a sex reversal protocol for rock bream.

Letrozole treatment alters hippocampal gene expression in common marmosets (Callithrix jacchus)

Aromatase inhibitors (AIs) are a class of drugs commonly given to patients with estrogen receptor (ER)-dependent breast cancers to reduce estrogenic stimulation. However, AIs like Letrozole are associated with negative side effects such as cognitive deficits, sleep disturbances and hot flashes. We have previously shown that these negative effects can be recapitulated in common marmosets (Callithrix jacchus) treated with Letrozole (20 μg daily) for 4 weeks and that marmosets treated with Letrozole show increased levels of estradiol in the hippocampus (Gervais et al., 2019). In order to better understand the mechanisms through which AIs affect cognitive function and increase steroid levels in the hippocampus, we used bulk, paired-end RNA-sequencing to examine differentially expressed genes among Letrozole-treated (LET; n = 8) and vehicle-treated (VEH; n = 8) male and female animals. Gene ontology results show significant reduction across hundreds of categories, some of the most significant being inflammatory response, stress response, MHC Class II protein complex binding, T-cell activation, carbohydrate binding and signaling receptor binding in LET animals. GSEA results indicate that LET females, but not LET males, show enrichment for hormonal gene sets. Based on the transcriptional changes observed, we conclude that AIs may differentially affect the sexes in part due to processes mediated by the CYP-450 superfamily. Ongoing studies will further investigate the longitudinal effects of AIs on behavior and whether AIs increase the risk of stress-induced neurodegeneration.

In vitro Development of Controlled-Release Nanoniosomes for Improved Delivery and Anticancer Activity of Letrozole for Breast Cancer Treatment

INTRODUCTION

Breast cancer is among the most prevalent mortal cancers in women worldwide. In the present study, an optimum formulation of letrozole, letrozole-loaded niosome, and empty niosome was developed, and the anticancer effect was assessed in in vitro MCF-7, MCF10A and MDA-MB-231 breast cancer cell lines.

MATERIALS AND METHODS

Various niosomal formulations of letrozole were fabricated through thin-film hydration method and characterized in terms of size, polydispersity index (PDI), morphology, entrapment efficiency (EE%), release kinetics, and stability. Optimized niosomal formulation of letrozole was achieved by response surface methodology (RSM). Antiproliferative activity and the mechanism were assessed by MTT assay, quantitative real-time PCR, and flow cytometry. Furthermore, cellular uptake of optimum formulation was evaluated by confocal electron microscopy.

RESULTS

The formulated letrozole had a spherical shape and showed a slow-release profile of the drug after 72 h. The size, PDI, and eEE% of nanoparticles showed higher stability at 4°C compared with 25°C. The drug release from niosomes was in accordance with Korsmeyer-Peppa's kinetic model. Confocal microscopy revealed the localization of drug-loaded niosomes in the cancer cells. MTT assay revealed that all samples exhibited dose-dependent cytotoxicity against breast cancer cells. The IC50 of mixed formulation of letrozole with letrozole-loaded niosome (L + L3) is the lowest value among all prepared formulations. L+L3 influenced the gene expression in the tested breast cancer cell lines by down-regulating the expression of Bcl 2 gene while up-regulating the expression of p53 and Bax genes. The flow cytometry results revealed that L + L3 enhanced the apoptosis rate in both MCF-7 and MDA-MB-231 cell lines compared with the letrozole (L), letrozole-loaded niosome (L3), and control sample.

CONCLUSION

Results indicated that niosomes could be a promising drug carrier for the delivery of letrozole to breast cancer cells.

Acetate restores hypothalamic-adipose kisspeptin status in a rat model of PCOS by suppression of NLRP3 immunoreactivity

PURPOSE

Polycystic ovary syndrome (PCOS) is a complex reproductive event that is delineated by endocrine/metabolic disorders. Alteration of kisspeptin status in the hypothalamus and adipose tissue is critical to increased endocrine/metabolic derangements in PCOS individuals, aggravating the clinical manifestation of PCOS and its complications. Short chain fatty acids (SCFAs) are crucial modulators of metabolic homeostasis. However, the role of SCFAs, particularly acetate on hypothalamic-adipose kisspeptin status (HAKS) in PCOS model is unknown. The present study hypothesized acetate as a key player in restoration of deranged HAKS, associated with experimental PCOS model.

METHODS

Three groups (n = 6/group) of female Wistar rats (120-150 g) were used. The groups were treated (po) for 21 days with vehicle, letrozole (1 mg/kg) with/without acetate (200 mg/kg) respectively.

RESULTS

Letrozole-treated animals had impaired glucose homeostasis, elevated testosterone, leptin and LH/FSH ratio and decreased GnRH and adiponectin with ovarian tissues revealing degenerated follicles and disrupted morphology. These animals also showed increased concentration of hypothalamic triglyceride (TG)/total cholesterol (TC), free fatty acid (FFA), and decreased concentration of TG/TC/FFA in visceral adipose tissue (VAT) with an increase in hypothalamic and VAT malondialdehyde, NF-κB/TNF-α and decreased glutathione/G6PD and hypothalamic but not VAT kisspeptin. Immunohistochemical analysis revealed the expression of NLRP3 inflammasome in the hypothalamus and VAT and all these changes were attenuated by acetate.

CONCLUSIONS

Altogether, the present results demonstrate that PCOS is characterized with hypothalamic-adipose inflammation, associated with immunohistochemical expression of NLRP3 with significant alteration of hypothalamic but not adipose kisspeptin. The results suggest that acetate restores kisspeptin status in PCOS animals. This beneficial effect is accompanied by repressed NLRP3 immunoreactivity.

Estrogen promotes fetal skeletal muscle myofiber development important for insulin sensitivity in offspring

Using our nonhuman primate baboon model, we showed that offspring born to mothers deprived of estrogen during the second half of gestation exhibited insulin resistance and a deficit in first phase insulin release. Although insulin resistance was not due to an impairment of fetal or offspring growth, nor to an alteration in adipose or hepatic sensitivity to insulin, skeletal muscle microvacularization critical for delivery of nutrients/insulin was significantly reduced in fetuses and offspring deprived of estrogen in utero. Skeletal muscle myofiber maturation occurs in utero and estrogen modulates myofiber growth in adults. Therefore, the current study determined whether fetal skeletal muscle development was altered in baboons in which estradiol levels were suppressed/restored during the second half of gestation by maternal treatment with letrozole ± estradiol benzoate. In estrogen-suppressed animals, fetal skeletal muscle fascicles were structurally less organized, smaller, and comprised of slow type I and fast type II fibers, the size, but not the number of which were smaller than in untreated baboons. Moreover, the proportion of non-muscle fiber tissue was greater and that of muscle fibers lower in estrogen-deprived fetuses. Thus, the maintenance of fetal body weight in estrogen-deprived animals was maintained at the expense of muscle fibers and likely reflected increased deposition of non-muscle proteins. Importantly, fetal skeletal muscle development, including fascicle organization, myofiber size and composition was normal in baboons treated with letrozole and estradiol benzoate. Collectively, these and our previous findings support our proposal that exposure of the fetus to estrogen is important for fetal skeletal muscle development and glucose homeostasis in adulthood.

Potentiation of temozolomide activity against glioblastoma cells by aromatase inhibitor letrozole

PURPOSE

The DNA alkylating agent temozolomide (TMZ), is the first-line therapeutic for the treatment of glioblastoma (GBM). However, its use is confounded by the occurrence of drug resistance and debilitating adverse effects. Previously, we observed that letrozole (LTZ), an aromatase inhibitor, has potent activity against GBM in pre-clinical models. Here, we evaluated the effect of LTZ on TMZ activity against patient-derived GBM cells.

METHODS

Employing patient-derived G76 (TMZ-sensitive), BT142 (TMZ-intermediately sensitive) and G43 and G75 (TMZ-resistant) GBM lines we assessed the influence of LTZ and TMZ on cell viability and neurosphere growth. Combination Index (CI) analysis was performed to gain quantitative insights of this interaction. We then assessed DNA damaging effects by conducting flow-cytometric analysis of ˠH2A.X formation and induction of apoptotic signaling pathways (caspase3/7 activity). The effects of adding estradiol on LTZ-induced cytotoxicity and DNA damage were also evaluated.

RESULTS

Co-treatment with LTZ at a non-cytotoxic concentration (40 nM) reduced TMZ IC50 by 8, 37, 240 and 640 folds in G76, BT-142, G43 and G75 cells, respectively. The interaction was deemed to be synergistic based on CI analysis. LTZ co-treatment also significantly increased DNA damaging effects of TMZ. Addition of estradiol abrogated these LTZ effects.

CONCLUSIONS

LTZ increases DNA damage and synergistically enhances TMZ activity in TMZ sensitive and TMZ-resistant GBM lines. These effects are abrogated by the addition of exogenous estradiol underscoring that the observed effects of LTZ may be mediated by estrogen deprivation. Our study provides a strong rationale for investigating the clinical potential of combining LTZ and TMZ for GBM therapy.

Luteal phase support for women trying to conceive by intrauterine insemination or sexual intercourse

BACKGROUND

Ovulation induction may impact endometrial receptivity due to insufficient progesterone secretion. Low progesterone is associated with poor pregnancy outcomes.

OBJECTIVES

To assess the effectiveness and safety of luteal phase support (LPS) in infertile women trying to conceive by intrauterine insemination or by sexual intercourse.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, LILACS, trial registries for ongoing trials, and reference lists of articles (from inception to 25 August 2021).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of LPS using progestogen, human chorionic gonadotropin (hCG), or gonadotropin-releasing hormone (GnRH) agonist supplementation in IUI or natural cycle.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcomes were live birth rate/ongoing pregnancy rate (LBR/OPR) and miscarriage.  MAIN RESULTS: We included 25 RCTs (5111 participants). Most studies were at unclear or high risk of bias. We graded the certainty of evidence as very low to low. The main limitations of the evidence were poor reporting and imprecision. 1. Progesterone supplement versus placebo or no treatment  We are uncertain if vaginal progesterone increases LBR/OPR (risk ratio (RR) 1.10, 95% confidence interval (CI) 0.81 to 1.48; 7 RCTs; 1792 participants; low-certainty evidence) or decreases miscarriage per pregnancy compared to placebo or no treatment (RR 0.70, 95% CI 0.40 to 1.25; 5 RCTs; 261 participants). There were no data on LBR or miscarriage with oral stimulation. We are uncertain if progesterone increases LBR/OPR in women with gonadotropin stimulation (RR 1.24, 95% CI 0.80 to 1.92; 4 RCTs; 1054 participants; low-certainty evidence) and oral stimulation (clomiphene citrate or letrozole) (RR 0.97, 95% CI 0.58 to 1.64; 2 RCTs; 485 participants; low-certainty evidence). One study reported on OPR in women with gonadotropin plus oral stimulation; the evidence from this study was uncertain (RR 0.73, 95% CI 0.37 to 1.42; 1 RCT; 253 participants; low-certainty evidence). Given the low certainty of the evidence, it is unclear if progesterone reduces miscarriage per clinical pregnancy in any stimulation protocol (RR 0.68, 95% CI 0.24 to 1.91; 2 RCTs; 102 participants, with gonadotropin; RR 0.67, 95% CI 0.30 to 1.50; 2 RCTs; 123 participants, with gonadotropin plus oral stimulation; and RR 0.53, 95% CI 0.25 to 1.14; 2 RCTs; 119 participants, with oral stimulation). Low-certainty evidence suggests that progesterone in all types of ovarian stimulation may increase clinical pregnancy compared to placebo (RR 1.38, 95% CI 1.10 to 1.74; 7 RCTs; 1437 participants, with gonadotropin; RR 1.40, 95% CI 1.03 to 1.90; 4 RCTs; 733 participants, with gonadotropin plus oral stimulation (clomiphene citrate or letrozole); and RR 1.44, 95% CI 1.04 to 1.98; 6 RCTs; 1073 participants, with oral stimulation). 2. Progesterone supplementation regimen  We are uncertain if there is any difference between 300 mg and 600 mg of vaginal progesterone for OPR and multiple pregnancy (RR 1.58, 95% CI 0.81 to 3.09; 1 RCT; 200 participants; very low-certainty evidence; and RR 0.50, 95% CI 0.05 to 5.43; 1 RCT; 200 participants, very low-certainty evidence, respectively). No other outcomes were reported for this comparison. There were three different comparisons between progesterone regimens. For OPR, the evidence is very uncertain for intramuscular (IM) versus vaginal progesterone (RR 0.59, 95% CI 0.34 to 1.02; 1 RCT; 225 participants; very low-certainty evidence); we are uncertain if there is any difference between oral and vaginal progesterone (RR 1.25, 95% CI 0.70 to 2.22; 1 RCT; 150 participants; very low-certainty evidence) or between subcutaneous and vaginal progesterone (RR 1.05, 95% CI 0.54 to 2.05; 1 RCT; 246 participants; very low-certainty evidence). We are uncertain if IM or oral progesterone reduces miscarriage per clinical pregnancy compared to vaginal progesterone (RR 0.75, 95% CI 0.43 to 1.32; 1 RCT; 81 participants and RR 0.58, 95% CI 0.11 to 3.09; 1 RCT; 41 participants, respectively). Clinical pregnancy and multiple pregnancy were reported for all comparisons; the evidence for these outcomes was very uncertain. Only one RCT reported adverse effects. We are uncertain if IM route increases the risk of adverse effects when compared with the vaginal route (RR 9.25, 95% CI 2.21 to 38.78; 1 RCT; 225 participants; very low-certainty evidence). 3. GnRH agonist versus placebo or no treatment  No trials reported live birth. The evidence is very uncertain about the effect of GnRH agonist in ongoing pregnancy (RR 1.10, 95% CI 0.70 to 1.74; 1 RCT; 291 participants, very low-certainty evidence), miscarriage per clinical pregnancy (RR 0.73, 95% CI 0.26 to 2.10; 2 RCTs; 79 participants, very low-certainty evidence) and clinical pregnancy (RR 1.00, 95% CI 0.68 to 1.47; 2 RCTs; 340 participants; very low-certainty evidence), and multiple pregnancy (RR 0.28, 95% CI 0.11 to 0.70; 2 RCTs; 126 participants). 4. GnRH agonist versus vaginal progesterone  The evidence for the effect of GnRH agonist injection on clinical pregnancy is very uncertain (RR 1.00, 95% CI 0.51 to 1.95; 1 RCT; 242 participants). 5. HCG injection versus no treatment  The evidence for the effect of hCG injection on clinical pregnancy (RR 0.93, 95% CI 0.40 to 2.13; 1 RCT; 130 participants) and multiple pregnancy rates (RR 1.03, 95% CI 0.22 to 4.92; 1 RCT; 130 participants) is very uncertain. 6. Luteal support in natural cycle No study evaluated the effect of LPS in natural cycle. We could not perform sensitivity analyses, as there were no studies at low risk of selection bias and not at high risk in other domains.

AUTHORS' CONCLUSIONS

We are uncertain if vaginal progesterone supplementation during luteal phase is associated with a higher live birth/ongoing pregnancy rate. Vaginal progesterone may increase clinical pregnancy rate; however, its effect on miscarriage rate and multiple pregnancy rate is uncertain. We are uncertain if IM progesterone improves ongoing pregnancy rates or decreases miscarriage rate when compared to vaginal progesterone. Regarding the other reported comparisons, neither oral progesterone nor any other medication appears to be associated with an improvement in pregnancy outcomes (very low-certainty evidence).

Short chain fatty acid, acetate restores ovarian function in experimentally induced PCOS rat model

BACKGROUND

Polycystic ovarian syndrome (PCOS) is pathogenically characterized with hyperandrogenism and metabolic alterations, which often result in ovarian changes and infertility in women of reproductive age. Epigenetic changes have been linked to the development of PCOS. However, the involvement of epigenetic regulator, histone deacetylase (HDAC) in PCOS-driven ovarian dysfunction is not clear. Howbeit, the present study hypothesized that acetate, an HDAC inhibitor (HDACi) would protect against ovarian dysfunction in experimentally induced PCOS.

MATERIALS AND METHODS

Female Wistar rats weighing 120-150 g were randomly divided into four groups (n = 6). The groups received vehicle, sodium acetate (200 mg/kg), letrozole (1 mg/kg) and letrozole with acetate by oral gavage respectively. The administrations were done daily for 21 days.

RESULTS

The rat model of PCOS had increased body weight and ovarian weight, 1-hr postload glucose and plasma insulin, testosterone and LH/FSH ratio as well as reduced insulin sensitivity and plasma 17-β estradiol and sex hormone binding globulin. This model of PCOS in addition showed a significant increase in plasma and ovarian triglyceride, total cholesterol, TNF-α and HDAC, and ovarian malondialdehyde as well as a significant reduction in ovarian glutathione peroxidase/reduced glutathione and NrF2 with the histology of ovarian tissues showing disrupted morphology with significant increase in the number of degenerated follicles compared with control group. These alterations were however attenuated when treated with HDACi, acetate.

CONCLUSION

Altogether, the present results suggest that acetate protects ovarian function with evidence of normal growing follicles and enhanced circulating 17-β estradiol by inhibition of HDAC.

Testosterone positively regulates vagina NO-induced relaxation: an experimental study in rats

PURPOSE

Female sexual response involves a complex interplay between neurophysiological mechanisms and the nitric oxide (NO)-mediated relaxation of clitoris and vagina. The aim of this study was to evaluate sex steroids regulation of the relaxant pathway in vagina, using a validated animal model.

METHODS

Subgroups of OVX Sprague-Dawley rats were treated with 17β-estradiol, testosterone, or testosterone and letrozole, and compared with a group of intact animals. Masson's trichrome staining was performed for morphological evaluation of the distal vaginal wall, in vitro contractility studies investigated the effect of OVX and in vivo treatments on vaginal smooth muscle activity. RNA from vaginal tissue was analyzed by semi-quantitative RT-PCR.

RESULTS

Immunohistochemical analysis showed that OVX induced epithelial and smooth muscle structural atrophy, testosterone and testo + letrozole increased the muscle bundles content and organization without affecting the epithelium while 17β-estradiol mediated the opposite effects. In vitro contractility studies were performed on noradrenaline pre-contracted vaginal strips from each experimental group. Acetylcholine (0.001-10 µM) stimulation induced a concentration-dependent relaxation, significantly reduced by NO-synthase inhibitor L-NAME and by guanylate cyclase inhibitor ODQ. OVX resulted in a decreased responsiveness to acetylcholine, restored by testosterone, with or without letrozole, but not by 17β-estradiol. OVX sensitivity to the NO-donor SNP was higher than in the control. Vardenafil, a PDE5 inhibitor, enhanced SNP effect in OVX + testosterone as well as in control, as supported by RNA expression analysis.

CONCLUSIONS

Our study demonstrates that testosterone improves the NO-mediated smooth muscle vaginal cells relaxation confirming its role in maintaining the integrity of muscular relaxant machinery.

Estrogen Promotes Microvascularization in the Fetus and Thus Vascular Function and Insulin Sensitivity in Offspring

We have shown that normal weight offspring born to estrogen-deprived baboons exhibited insulin resistance, although liver and adipose function and insulin receptor and glucose transporter expression were unaltered. The blood microvessels have an important role in insulin action by delivering insulin and glucose to target cells. Although little is known about the regulation of microvessel development during fetal life, estrogen promotes capillary proliferation and vascular function in the adult. Therefore, we tested the hypothesis that estrogen promotes fetal microvessel development and thus vascular function and insulin sensitivity in offspring. Capillary/myofiber ratio was decreased 75% (P < 0.05) in skeletal muscle, a major insulin target tissue, of fetal baboons in which estradiol levels were depleted by administration of aromatase inhibitor letrozole. This was sustained after birth, resulting in a 50% reduction (P < 0.01) in microvessel expansion; 65% decrease (P < 0.01) in arterial flow-mediated dilation, indicative of vascular endothelial dysfunction; and 35% increase (P < 0.01) in blood pressure in offspring from estrogen-deprived baboons, changes prevented by letrozole and estradiol administration. Along with vascular dysfunction, peak insulin and glucose levels during a glucose tolerance test were greater (P < 0.05 to P < 0.01) and the homeostasis model of insulin resistance 2-fold higher (P < 0.01) in offspring of letrozole-treated than untreated animals, indicative of insulin resistance. This study makes the novel discovery that estrogen promotes microvascularization in the fetus and thus normal vascular development and function required for eliciting insulin sensitivity in offspring and that placental hormonal secretions, independent from improper fetal growth, are an important determinant of risk of developing insulin resistance.

Glyceollins Trigger Anti-Proliferative Effects in Hormone-Dependent Aromatase-Inhibitor-Resistant Breast Cancer Cells through the Induction of Apoptosis

Aromatase inhibitors (AIs) are standard treatment for estrogen-dependent postmenopausal breast tumors; however, resistance develops leading to tumor relapse and metastasis. We previously demonstrated that glyceollin inhibits proliferation, survival, and migration of hormone-independent letrozole-resistant breast cancer. Since many AI-resistant tumors remain hormone-dependent, identifying distinctions between estrogen-receptor-positive (ER+) and ER-negative (ER-) AI-resistant tumor response to therapy is critical. We hypothesize that treating ER+ letrozole-resistant T47D breast cancer cells (T47DaromLR) with a combination of 10 μM glyceollin and 0.5 μM lapatinib (a dual EGFR/HER2 inhibitor) will decrease cell proliferation through induction of apoptosis. The T47DaromLR cells were found to overexpress HER2 and MAPK while maintaining aromatase and ER levels compared to their letrozole-sensitive (T47Darom) counterparts. In the absence of estrogen stimulation, glyceollin ± lapatinib had no effect on the proliferation of the T47Darom cells, while glyceollin treatment caused 46% reduction in the proliferation of T47DaromLR cells, which was further diminished when combined with lapatinib. While neither agent influenced cell migration, glyceollin and lapatinib reduced S and G2/M phase cell entry and exclusively induced apoptosis by 1.29-fold in the T47DaromLR cells. Taken together, these results suggest that glyceollins and lapatinib may have potential as a novel combination therapeutic approach for hormone-dependent, letrozole-resistant tumors.

Letrozole protects against cadmium-induced inhibition of spermatogenesis via LHCGR and Hsd3b6 to activate testosterone synthesis in mice

The heavy metal cadmium is proposed to be one of the environmental endocrine disruptors of spermatogenesis. Cadmium-induced inhibition of spermatogenesis is associated with a hormone secretion disorder. Letrozole is an aromatase inhibitor that increases peripheral androgen levels and stimulates spermatogenesis. However, the potential protective effects of letrozole on cadmium-induced reproductive toxicity remain to be elucidated. In this study, male mice were administered CdCl2 (4 mg/kg BW) orally by gavage alone or in combination with letrozole (0.25 mg/kg BW) for 30 days. Cd exposure caused a significant decreases in body weight, sperm count, motility, vitality, and plasma testosterone levels. Histopathological changes revealed extensive vacuolization and decreased spermatozoa in the lumen. However, in the Cd + letrozole group, letrozole treatment compensated for deficits in sperm parameters (count, motility, and vitality) induced by Cd. Letrozole treatment significantly increased serum testosterone levels, which were reduced by Cd. Histopathological studies revealed a systematic array of all germ cells, a preserved basement membrane and relatively less vacuolization. For a mechanistic examination, RNA-seq was used to profile alterations in gene expression in response to letrozole. Compared with that in the Cd-treated group, RNA-Seq analysis showed that 214 genes were differentially expressed in the presence of letrozole. Gene ontology (GO) enrichment analysis and KEGG signaling pathway analysis showed that steroid biosynthetic processes were the processes most affected by letrozole treatment. Furthermore, we found that the expression of the testosterone synthesis-related genes LHCGR (luteinizing hormone/choriogonadotropin receptor) and Hsd3b6 (3 beta- and steroid delta-isomerase 6) was significantly downregulated in Cd-treated testes, but these genes maintained similar expression levels in letrozole-treated testes as those in the control group. However, the transcription levels of inflammatory cytokines, such as IL-1β and IL-6, and oxidative stress-related genes (Nrf2, Nqo1, and Ho-1) showed no changes. The present study suggests that the potential protective effect of letrozole on Cd-induced reproductive toxicity might be mediated by the upregulation of LHCGR and Hsd3b6, which would beneficially increase testosterone synthesis to achieve optimum protection of sperm quality and spermatogenesis.

Multifaceted epigenetic regulation of porcine testicular aromatase

Testicular aromatase catalyzes the synthesis of estradiol, which contributes to regulation of porcine Sertoli cell proliferation and postpubertal maintenance of Sertoli cell numbers. Although aromatase enzymatic activity decreases with age and is persistently reprogrammed by prepubertal treatment with the aromatase inhibitor letrozole, the molecular bases for regulation have not been identified. DNA methylation was examined as a potential regulatory mechanism using DNA from Leydig cells isolated from 16-, 40-, and 68-week-old boars and from 68- week-old littermates treated with the aromatase inhibitor, letrozole. Methylation levels of individual CpG dinucleotides located in the distal untranslated exon 1 of the relevant aromatase encoding gene, CYP19A3, were quite high in Leydig cell DNA, and increased further with maturity of boar (P < 0.05), while aromatase activity and transcript abundance decreased more than two-fold. However, reduced aromatase activity following letrozole treatment was not accompanied by altered DNA methylation. Testicular expression of miR378 was altered by prepubertal treatment with letrozole. The data provide evidence for two different epigenetic mechanisms that regulate aromatase expression and enzymatic activity in the boar testis.

Effect of Letrozole Administration as a Selective Aromatase Inhibitor on Male Rat's Reproductive Performance

This study was designed to investigate the effect of administrating a selective aromatase inhibitor, letrozole, on the parameters of the rat's sperm and testicular histomorphology. A total of 40 male Wistar rats with an age of about 5 months old and an average weight of 190±10 g were divided randomly into 4 groups (n=10 each) and treated for 6 weeks. The first group (C) was given normal saline only as a control group. The second (T1), third (T2), and fourth (T3) groups received doses of 0.5, 1, and 1.5 mg/animal letrozole, respectively. At the end of the experiment (42 days), all animals were euthanized and the samples were obtained for more evolutions. The results of this study showed a significant increase in sperms quality (P-value≤0.05) while indicating a significant decrease in sperm abnormality in the T1 group, compared to the C group. Moreover, there was a significant difference represented by an increase in sperm quality, and a significant difference represented by a decrease in sperms abnormality in the T2 group, compared to the C group. On the other hand, there was a significant difference represented by an increase in sperm quality, and a significant difference represented by a decrease in sperm abnormality in the T3 group, compared to the T2 group. Normal somniferous tubules with high spermatoscopy counts were shown in histologic sections in the control group, primary and secondary spermatocytes with spermatozoa. In the T1 group, there was adequate spermatogenesis with a thick basement membrane. In the T2 group, there was normal testicular tissue with a significant increase in spermatogenic activity and number. In the T3 group, there was no significant atrophy or other pathology. The results of the current study suggested that letrozole improved spermatogenesis while causing no visible pathological alterations in testis tissue.

Letrozole Accelerates Metabolic Remodeling through Activation of Glycolysis in Cardiomyocytes: A Role beyond Hormone Regulation

Estrogen receptor-positive (ER+) breast cancer patients are recommended hormone therapy as a primary adjuvant treatment after surgery. Aromatase inhibitors (AIs) are widely administered to ER+ breast cancer patients as estrogen blockers; however, their safety remains controversial. The use of letrozole, an AI, has been reported to cause adverse cardiovascular effects. We aimed to elucidate the effects of letrozole on the cardiovascular system. Female rats exposed to letrozole for four weeks showed metabolic changes, i.e., decreased fatty acid oxidation, increased glycolysis, and hypertrophy in the left ventricle. Although lipid oxidation yields more ATP than carbohydrate metabolism, the latter predominates in the heart under pathological conditions. Reduced lipid metabolism is attributed to reduced β-oxidation due to low circulating estrogen levels. In letrozole-treated rats, glycolysis levels were found to be increased in the heart. Furthermore, the levels of glycolytic enzymes were increased (in a high glucose medium) and the glycolytic rate was increased in vitro (H9c2 cells); the same was not true in the case of estrogen treatment. Reduced lipid metabolism and increased glycolysis can lower energy supply to the heart, resulting in predisposition to heart failure. These data suggest that a letrozole-induced cardiac metabolic remodeling, i.e., a shift from β-oxidation to glycolysis, may induce cardiac structural remodeling.

Letrozole Supplementation and the Increased Risk of Elevated Progesterone Levels on Trigger Day

Although using letrozole (LE) during in vitro fertilisation and intracytoplasmic sperm injection (IVF/ICSI) has many advantages, it remains unclear whether LE induces an increase in progestogen during the late follicular phase. The objective of this study was to investigate whether progesterone levels increased under antagonist protocols supplemented with LE on the trigger day using a retrospective cohort study. The study included 1,133 women who underwent IVF/ICSI cycles from January 2018 to June 2020. After propensity score matching (PSM) for baseline characteristics, 266 patients with gonadotropin-releasing hormone-antagonist (GnRH-ant) were matched to 266 patients with letrozole + GnRH-ant (LE GnRH-ant) (PSM 1 cohort), and 283 patients with gonadotropin-releasing hormone-agonist (GnRH-a) were matched to 283 patients with LE GnRH-ant (PSM 2 cohort). In the PSM 1 cohort, patients in the LE GnRH-a group presented higher progesterone levels (1.22 ± 0.95 ng/mL vs 0.86 ± 0.60 ng/mL, P < 0.001), with a higher proportion of patients with progesterone level > 1.5 ng/mL (24.81% vs 7.52%, P < 0.001). In PSM 2 cohort, patients in the LE GnRH-a group presented higher progesterone levels on trigger day (1.23 ± 0.91 ng/mL vs 0.98 ± 0.61 ng/mL, P < 0.001), with a higher proportion of patients with progesterone level > 1.5 ng/mL (25.45% vs 12.70%, P < 0.001). In the PSM 1 cohort, progesterone levels on the trigger day increased by 0.05 ng/mL, with an increase in every retrieved oocyte in the LE GnRH-ant group (β 0.05 ng/mL [95% CI 0.04, 0.06], P < 0.001), whereas an increase of 0.02 ng/mL was observed in the GnRH-ant group (β 0.02 ng/mL [95% CI 0.01, 0.03], P < 0.001), with P for interaction being 0.0018. In the PSM 2 cohort, progesterone levels on the trigger day increased by 0.05 ng/mL with an increase in every retrieved oocyte in the LE GnRH-ant group (β 0.05 ng/mL [95% CI 0.04, 0.06], P < 0.001), whereas an increase of 0.02 ng/mL was observed in the GnRH-a group (β 0.02 ng/mL [95% CI 0.01, 0.03], P < 0.001), with P for interaction being 0.0002. LE supplementation on the antagonist protocols may increase progesterone levels in the late follicular stage.

Effects of neural-derived estradiol on actin polymerization and synaptic plasticity-related proteins in prefrontal and hippocampal cells of mice

Neural-derived 17β-estradiol (E2) plays an important role in the synaptic plasticity of the hippocampus and prefrontal cortex, but the mechanism is not well defined. This study was designed to explore the effect and mechanism of neural-derived E2 on synaptic plasticity of the hippocampus and prefrontal cortex. Primary cultured hippocampal and prefrontal cells in mice were randomly divided into the DMSO (D), aromatase (Rate-limiting enzymes for E2 synthesizes) inhibitor letrozole (L), and ERs antagonist (MPG) treated groups. After intervention for 48 h, the cell was collected, and then, the expressions of AMPA-receptor subunit GluR1 (GluR1), synaptophysin (SYN), p-21-Activated kinase (PAK) phosphorylation, Rho kinase (ROCK), p-Cofilin, F-actin, and G-actin proteins were detected. Letrozole or ER antagonists inhibited the expression of GluR1, F-actin/G-actin, p-PAK and p-Cofilin proteins in prefrontal cells significantly. And the expressions of GluR1 and F-actin/G-actin proteins were declined in hippocampal cells markedly after adding letrozole or ERs antagonists. In conclusion, neural-derived E2 and ERs regulated the synaptic plasticity, possibly due to promoting actin polymerization in prefrontal and hippocampal cells. The regional specificity in the effect of neural-derived E2 and ERs on the actin polymerization-related pathway may provide a theoretical basis for the functional differences between the hippocampus and prefrontal cortex.

Cysteine-Cysteine Motif Chemokine Receptor 5 Expression in Letrozole-Induced Polycystic Ovary Syndrome Mice

Polycystic ovary syndrome (PCOS), which affects 5–10% of women of reproductive age, is associated with reproductive and metabolic disorders, such as chronic anovulation, infertility, insulin resistance, and type 2 diabetes. However, the mechanism of PCOS is still unknown. Therefore, this study used a letrozole-exposed mouse model in which mice were orally fed letrozole for 20 weeks to investigate the effects of letrozole on the severity of reproductive and metabolic consequences and the expression of cysteine–cysteine motif chemokine receptor 5 (CCR5) in letrozole-induced PCOS mice. The letrozole-treated mice showed a disrupted estrous cycle and were arrested in the diestrus phase. Letrozole treatment also increased plasma testosterone levels, decreased estradiol levels, and caused multicystic follicle formation. Furthermore, histological analysis of the perigonadal white adipose tissue (pgWAT) showed no significant difference in the size and number of adipocytes between the letrozole-treated mice and the control group. Further, the letrozole-treated mice demonstrated glucose intolerance and insulin resistance during oral glucose and insulin tolerance testing. Additionally, the expression of CCR5 and cysteine-cysteine motif ligand 5 (CCL5) were significantly higher in the pgWAT of the letrozole-treated mice compared with the control group. CCR5 and CCL5 were also significantly correlated with the homeostasis model assessment of insulin resistance (HOMA-IR). Finally, the mechanisms of insulin resistance in PCOS may be caused by an increase in serine phosphorylation and a decrease in Akt phosphorylation.

Repurposing new drug candidates and identifying crucial molecules underlying PCOS Pathogenesis Based On Bioinformatics Analysis

BACKGROUNDS

Polycystic ovary syndrome affects 7% of women of reproductive ages. Poor-quality oocytes, along with lower cleavage and implantation rates, reduce fertilization.

OBJECTIVE

This study aimed to determine crucial molecular mechanisms behind PCOS pathogenesis and repurpose new drug candidates interacting with them. To predict a more in-depth insight, we applied a novel bioinformatics approach to analyze interactions between the drug-related and PCOS proteins in PCOS patients.

METHODS

The newest proteomics data was retrieved from 16 proteomics datasets and was used to construct the PCOS PPI network using Cytoscape. The topological network analysis determined hubs and bottlenecks. The MCODE Plugin was used to identify highly connected regions, and the associations between PCOS clusters and drug-related proteins were evaluated using the Chi-squared/Fisher's exact test. The crucial PPI hub-bottlenecks and the shared molecules (between the PCOS clusters and drug-related proteins) were then investigated for their drug-protein interactions with previously US FDA-approved drugs to predict new drug candidates.

RESULTS

The PI3K/AKT pathway was significantly related to one PCOS subnetwork and most drugs (metformin, letrozole, pioglitazone, and spironolactone); moreover, VEGF, EGF, TGFB1, AGT, AMBP, and RBP4 were identified as the shared proteins between the PCOS subnetwork and the drugs. The shared top biochemical pathways between another PCOS subnetwork and rosiglitazone included metabolic pathways, carbon metabolism, and citrate cycle, while the shared proteins included HSPB1, HSPD1, ACO2, TALDO1, VDAC1, and MDH2. We proposed some new candidate medicines for further PCOS treatment investigations, such as copper and zinc compounds, reteplase, alteplase, gliclazide, Etc.

CONCLUSION

Some of the crucial molecules suggested by our model have already been experimentally reported as critical molecules in PCOS pathogenesis. Moreover, some repurposed medications have already shown beneficial effects on infertility treatment. These previous experimental reports confirm our suggestion for investigating our other repurposed drugs (in vitro and in vivo).

Differential biological effects of aromatase inhibitors: Apoptosis, autophagy, senescence and modulation of the hormonal status in breast cancer cells

Estrogen receptor-positive (ER⁺) breast carcinomas are the most common subtype, corresponding to 60% of the cases in premenopausal and 75% in postmenopausal women. The third-generation of aromatase inhibitors (AIs), the non-steroidal Anastrozole (Ana) and Letrozole (Let) and the steroidal Exemestane (Exe), are considered a first-line endocrine therapy for postmenopausal women. Despite their clinical success, the development of resistance is the major setback in clinical practice. Nevertheless, the lack of cross-resistance between AIs hints that these drugs may act through distinct mechanisms. Therefore, this work studied the different effects induced by AIs on biological processes, such as cell proliferation, death, autophagy and senescence. Moreover, their effects on the regulation of the hormonal environment were also explored. The non-steroidal AIs induce senescence, through increased YPEL3 expression, on aromatase-overexpressing breast cancer cells (MCF-7aro), whereas Exe promotes a cytoprotective autophagy, thus blocking senescence induction. In addition, in a hormone-enriched environment, the non-steroidal AIs prevent estrogen signaling, despite up-regulating the estrogen receptor alpha (ERα), while Exe down-regulates ERα and maintains its activation. In these conditions, all AIs up-regulate the androgen receptor (AR) which blocks EGR3 transcription in Exe-treated cells. On the other hand, in hormone-depleted conditions, a crosstalk between AR and ERα occurs, enhancing the estrogenic effects of Exe. This indicates that Exe modulates both ERα and AR, while Ana and Let act as pure AIs. Thus, this study highlights the potential clinical benefit of combining AR antagonists with Exe and discourages the sequential use of Exe as second-line therapy in postmenopausal breast cancer.

Differential expression and interaction of melatonin and thyroid hormone receptors with estrogen receptor α improve ovarian functions in letrozole-induced rat polycystic ovary syndrome

AIMS

The objective of the present study was to investigate the effect of melatonin and L-thyroxine (T4) on the expression of various receptors, and some metabolic, reproductive, and gonadotropic hormones in letrozole-induced polycystic ovary syndrome (PCOS) in rats.

MATERIAL AND METHODS

Assessment of gravimetric, hormonal profile and thyroid histology and relative expression of melatonin receptors (MT1, MT2) and estrogen receptor α (Erα) in thyroid and ovary, and type II iodothyronine deiodinase (Dio2) and thyroid hormone receptor α (TRα) in ovary were done according to standard protocols.

KEY FINDINGS

A significant increase in thyroid follicles numbers was noted in the hyperthyroid rat. T4 treatment to PCOS showed the expected increment in the circulating level of triiodothyronine (T) and T₄. Melatonin and T4 treatment of PCOS rats resulted in a significant decrease in the circulating level of T₃ and T₄. Hyperthyroid rats showed a decrement in plasma melatonin levels. However, T4 treatment to PCOS rats showed increased circulating melatonin levels, and a decrease in the circulating level of gonadotropins (LH and FSH), and testosterone. Melatonin treatment to PCOS-hyperthyroid rats resulted in the normal expression of ovarian and thyroid MT1 and ERα, receptors, which had been altered in PCOS and hyperthyroid rats, without any significant change in the MT2 receptor.

SIGNIFICANCE

The present findings suggest a fine interplay and cross-talk via melatonin and its two receptors with ERα, TRα, and Dio₂ in thyroid and ovarian tissue during PCOS and hyperthyroidism pathogenicity.

Intestinal Flora is a Key Factor in Insulin Resistance and Contributes to the Development of Polycystic Ovary Syndrome

CONTEXT

The key gut microbial biomarkers for polycystic ovarian syndrome (PCOS) and how dysbiosis causes insulin resistance and PCOS remain unclear.

OBJECTIVE

To assess the characteristics of intestinal flora in PCOS and explore whether abnormal intestinal flora can affect insulin resistance and promote PCOS and whether chenodeoxycholic acid (CDCA) can activate intestinal farnesoid X receptor (FXR), improving glucose metabolism in PCOS.

SETTING AND DESIGN

The intestinal flora of treatment-naïve PCOS patients and hormonally healthy controls was analyzed. Phenotype analysis, intestinal flora analysis, and global metabolomic profiling of caecal contents were performed on a letrozole-induced PCOS mouse model; similar analyses were conducted after 35 days of antibiotic treatment on the PCOS mouse model, and glucose tolerance testing was performed on the PCOS mouse model after a 35-day CDCA treatment. Mice receiving fecal microbiota transplants from PCOS patients or healthy controls were evaluated after 10 weeks.

RESULTS

Bacteroides was significantly enriched in treatment-naïve PCOS patients. The enrichment in Bacteroides was reproduced in the PCOS mouse model. Gut microbiota removal ameliorated the PCOS phenotype and insulin resistance and increased relative FXR mRNA levels in the ileum and serum fibroblast growth factor 15 levels. PCOS stool-transplanted mice exhibited insulin resistance at 10 weeks but not PCOS. Treating the PCOS mouse model with CDCA improved glucose metabolism.

CONCLUSIONS

Bacteroides is a key microbial biomarker in PCOS and shows diagnostic value. Gut dysbiosis can cause insulin resistance. FXR activation might play a beneficial rather than detrimental role in glucose metabolism in PCOS.

Gene Expression of Takifugu rubripes Gonads During AI- or MT-induced Masculinization and E2-induced Feminization

Elucidating the global molecular changes that occur during aromatase inhibitor (AI)- or 17α-methyltestosterone (MT)-induced masculinization and estradiol-17β (E2)-induced feminization is critical to understanding the roles that endocrine and genetic factors play in regulating the process of sex differentiation in fish. Here, fugu larvae were treated with AI (letrozole), MT, or E2 from 25 to 80 days after hatching (dah), and gonadal transcriptomic analysis at 80 dah was performed. The expression of dmrt1, gsdf, foxl2, and other key genes (star, hsd3b1, cyp11c1, cyp19a1a, etc.) involved in the steroid hormone biosynthesis pathway were found be altered. The expression of dmrt1, gsdf, cyp19a1a, and foxl2 was further verified by quantitative polymerase chain reaction. In the control group, the expression of dmrt1 and gsdf was significantly higher in XY larvae than in XX larvae, while the expression of foxl2 and cyp19a1a was significantly higher in XX larvae than in XY larvae (P < .05). AI treatment suppressed the expression of foxl2 and cyp19a1a, and induced the expression of dmrt1 and gsdf in XX larvae. MT treatment suppressed the expression of foxl2, cyp19a1a, dmrt1, and gsdf in XX larvae. E2 treatment suppressed the expression of dmrt1 and gsdf, but did not restore the expression of foxl2 and cyp19a1a in XY larvae. The shared response following AI, MT, and E2 treatment suggested that these genes are essential for sex differentiation. This finding offers some insight into AI or MT-induced masculinization, and E2-induced femininization in fugu.

Does letrozole treatment have favorable effects on the lipid profile? A systematic review and meta-analysis of randomized clinical trials

As an aromatase inhibitor, letrozole reduces estrogen levels, affecting lipid indices because of the positive role of estrogens in modulating lipoproteins and lipids. Thus, our aim was to meta-analyze data regarding letrozole administration and its effects on the traditional lipid profile. A systematic review and meta-analysis of randomized clinical trials (RCTs) were performed based on the PRISMA guidelines. Web of Science, Scopus, PubMed/Medline, and EMBASE databases were searched until February 11, 2021. From 341 potentially relevant publications, 8 RCTs were selected. All studies used 2.5 mg/d of letrozole. Total cholesterol changed significantly by -6.28 mg/dL (95% CI: -8.73, -3.84, P < 0.001) and HDL-C by -4.40 mg/dL (95% CI: -5.30 to -3.50, p < 0.001) in letrozole group when compared to the control group. Taking into account this comparison between groups, in contrast, LDL-C (WMD: -2.50 mg/dL, 95% CI: -9.94, 4.93, p = 0.510) and triglycerides (WMD: -0.89 mg/dL, 95% CI: -6.87 to 5.07, p = 0.768) did not alter. In conclusion, letrozole administration decreased the concentrations of HDL-C and tocal cholesterol, but not of triglycerides and LDL-C.

The aromatase inhibitor letrozole restores FADS2 function in ER+ MCF7 human breast cancer cells

PURPOSE

Plasticity in fatty acid metabolism is increasingly recognized as a major feature influencing cancer progression and efficacy of treatments. Estrogen receptor positive MCF7 human breast cancer cells have long been known to have no FADS2-mediated Δ6-desaturase activity. Our objective was to examine the effect of estrogen and the "antiestrogen" aromatase inhibitor letrozole, on Δ5- and Δ6-desaturase synthesized fatty acids in vitro.

METHODS

Eicosa-11,14-dienoic acid (20:2n-6), a known substrate for both FADS1 and FADS2, was used as a sentinel of relative FADS2 and FADS1 activity. MCF7 cells and four additional estrogen responsive wild type cell lines (HepG2, SK-N-SH, Y79 and Caco2) were studied. FAME were quantified by GC-FID and structures identified by GCCACI-MS/MS.

RESULTS

In all five cell lines, estrogen caused a dose dependent decrease in sciadonic acid (5,11,14-20:3, ScA) via apparent inhibition of FADS1 activity, and had no effect on FADS2 catalyzed synthesis of dihomo-gamma linolenic acid (8,11,14-20:3; DGLA). In MCF7 cells, letrozole caused a dose dependent increase in FADS2-catalyzed DGLA synthesis, which plateaued in SK-N-SH cells.

CONCLUSION

Letrozole restores Δ6-desaturase mediated synthesis of the anti-inflammatory PGE1-precursor DGLA in vitro and is the first endocrine-active agent to have opposing effects on FADS1 and FADS2 catalyzed activities.

Super Magnetic Niosomal Nanocarrier as a New Approach for Treatment of Breast Cancer: A Case Study on SK-BR-3 and MDA-MB-231 Cell Lines

In the present study, a magnetic niosomal nanocarrier for co-delivery of curcumin and letrozole into breast cancer cells has been designed. The magnetic NiCoFe2O4 core was coated by a thin layer of silica, followed by a niosomal structure, allowing us to load letrozole and curcumin into the silica layer and niosomal layer, respectively, and investigate their synergic effects on breast cancer cells. Furthermore, the nanocarriers demonstrated a pH-dependent release due to the niosomal structure at their outer layer, which is a promising behavior for cancer treatment. Additionally, cellular assays revealed that the nanocarriers had low cellular uptake in the case of non-tumorigenic cells (i.e., MCF-10A) and related high viability but high cellular uptake in cancer cell lines (i.e., MDA-MB-231 and SK-BR-3) and related low viability, which is evidenced in their high cytotoxicity against different breast cancer cell lines. The cytotoxicity of the letrozole/curcumin co-loaded nanocarrier is higher than that of the aqueous solutions of both drugs, indicating their enhanced cellular uptake in their encapsulated states. In particular, NiCoFe2O4@L-Silica-L@C-Niosome showed the highest cytotoxicity effects on MDA-MB-231 and SK-BR-3 breast cancer cells. The observed cytotoxicity was due to regulation of the expression levels of the studied genes in breast cancer cells, where downregulation was observed for the Bcl-2, MMP 2, MMP 9, cyclin D, and cyclin E genes while upregulation of the expression of the Bax, caspase-3, and caspase-9 genes was observed. The flow cytometry results also revealed that NiCoFe2O4@L-Silica-L@C-Niosome enhanced the apoptosis rate in both MDA-MB-231 and SK-BR-3 cells compared to the control samples. The findings of our research show the potential of designing magnetic niosomal formulations for simultaneous targeted delivery of both hydrophobic and hydrophilic drugs into cancer cells in order to enhance their synergic chemotherapeutic effects. These results could open new avenues into the future of nanomedicine and the development of theranostic agents.

Circulating miR-30b levels increase during male puberty

OBJECTIVE

The role of miRNA as endocrine regulators is emerging, and microRNA mir-30b has been reported to repress Mkrn3. However, the expression of miR-30b during male puberty has not been studied.

DESIGN AND METHODS

Circulating relative miR-30b expression was assessed in sera of 26 boys with constitutional delay of growth and puberty (CDGP), treated with low-dose testosterone (T) (n =11) or aromatase inhibitor letrozole (Lz) (n =15) for 6 months and followed up to 12 months (NCT01797718). The associations between the relative expression of miR-30b and hormonal markers of puberty were evaluated.

RESULTS

During the 12 months of the study, circulating miR-30b expression increased 2.4 ± 2.5 (s.d.) fold (P = 0.008) in all boys, but this change did not correlate with corresponding changes in LH, testosterone, inhibin B, FSH, or testicular volume (P = 0.25-0.96). Lz-induced activation of the hypothalamic-pituitary-gonadal (HPG) axis was associated with more variable miR-30b responses at 3 months (P < 0.05), whereas those treated with T exhibited significant changes in relative miR-30b levels in the course the study (P < 0.01-0.05).

CONCLUSIONS

Circulating miR-30b expression in boys with CDGP increases in the course of puberty, and appears to be related to the activity of the HPG axis.

Changes in testicular gene expression following reduced estradiol synthesis: A complex pathway to increased porcine Sertoli cell proliferation

Porcine Sertoli cell number including number present at puberty is increased if testicular estradiol synthesis is reduced during the neonatal interval. Evaluating the changes in gene expression during the crucial interval of suppressed estradiol that leads to the increased Sertoli cell population will increase our understanding of Sertoli cell biology but this evaluation first required a more precise determination of the critical interval for treatment and timing of a detectable response. Previously, reduced testicular estrogens from 1 week of age were accompanied by increased Sertoli cell number at 6.5 weeks of age but the age at which Sertoli cell numbers were initially increased was unknown, one of the current objectives. Additional experiments were designed to further delineate the essential timing of treatment for the Sertoli cell response. Finally, changes in gene expression induced by the reduced estradiol synthesis were evaluated to elucidate molecular mechanisms. Experimental design typically consisted of one member of littermate pairs of boars treated with the aromatase inhibitor, letrozole, beginning at 1 week of age and the remaining member treated with canola oil vehicle. Weekly treatments continued through 5 weeks of age or tissue collection, whichever came first. Increases in Sertoli cell numbers were not detectable prior to 6.5 weeks of age and persistent treatment through 5 weeks of age was required to induce the increase in Sertoli cell numbers. This increase resulted from prolonging the first interval of Sertoli cell proliferation in the treated animals. Few genes exhibited dramatically altered transcription and similarities in pathway analysis or principal modified genes were quite limited in 2, 3, and 5-week-old boars. The critical timing and prolonged treatment required and the sequential changes in gene expression suggest a complex mechanism is involved in this model of increased proliferation of Sertoli cells.

GnRH protective effects against amyloid β-induced cognitive decline: A potential role of the 17β-estradiol

INTRODUCTION

The 17β-estradiol (E2) enhances hippocampal dendritic spine synapses, facilitates learning processes, and exerts neuroprotection. Brain estrogen decline has been reported in Alzheimer's disease. The role of GnRH in modulating steroid biosynthesis convinced us to examine whether hippocampal GnRH administration could enhance the local E2 levels and overcome the development of cognition decline in amyloid β (Aβ) neurotoxicity. To explore if GnRH acts through regulating E2 synthesis, letrozole, an aromatase inhibitor, has been applied in combination with GnRH.

METHODS

Female rats received an intracerebroventricular injection of Aβ. The GnRH and, or letrozole were injected into the CA1 for 14 consecutive days. Working memory, novel object recognition memory, and anxiety-like behavior were evaluated. Serum and hippocampal E2 levels were measured. Hippocampal mRNA expression of GnRH (GnRH-R) and E2 (ERα and ERβ) receptors was assessed. GnRH effect on the excitability of pyramidal cells was studied by in vivo single-unit recording.

RESULTS

GnRH increased hippocampal E2 levels, evoked an increase in the spontaneous firing of pyramidal neurons, and caused mRNA overexpression of hippocampal GnRH receptors. GnRH prevented the adverse effects of Aβ on working memory, NOR index, and anxiogenic behavior. Letrozole did not reverse GnRH modulatory effects on hippocampal E2 levels and neuroprotection.

CONCLUSION

GnRH prevented the Aβ-induced memory deficit, which may be mediated through hippocampal E2 levels enhancement. The electrophysiological analysis revealed the enhanced neuronal excitability in the CA1 region. All these data suggest that GnRH might be a promising candidate that reduces anxiety and improves memory indices in the context of Aβ neurotoxicity.

Involvement of endogenous testosterone in hepatic steatosis in women with polycystic ovarian syndrome

AIMS

The prevalence of nonalcoholic fatty liver disease (NAFLD) is higher in women with polycystic ovarian syndrome (PCOS) than that in healthy women. This association can be explained in part by the resistance to insulin and the prevalence of obesity, which are fueled by high androgen levels. However, there is little evidence of the involvement of endogenous testosterone in hepatic steatosis in women with PCOS. Here, we treated Sprague Dawley rats with the aromatase inhibitor, letrozole, to increase the endogenous testosterone level and to decrease the estradiol levels. We also quantified the testosterone levels in human serum specimens and HepG2 cells to investigate the effects of androgens on hepatic steatosis and liver dysfunction.

RESULTS

Twenty-nine PCOS patients and twenty healthy women were enrolled. Alanine transaminase and aspartate transaminase (AST) levels were increased in women with PCOS, and a strong correlation between testosterone and AST levels was observed. After letrozole treatment for 90 days, rats were significantly more obese, with animals developing hepatic steatosis and moderate insulin resistance. Additional experiments revealed that excess androgen inhibited the AMP-activated protein kinase alpha pathway in letrozole-treated livers and dihydrotestosterone (DHT)-treated HepG2 cells, thereby causing steatosis.

INNOVATION AND CONCLUSION

Our results show that an elevated endogenous testosterone level can induce hepatic steatosis. Decreasing the endogenous testosterone level in hepatocytes may represent a new approach in the treatment of NAFLD in PCOS patients.

Efficacy of everolimus combined with endocrine therapy in HR-positive/HER-2-negativeadvanced breast cancer

PURPOSE

To explore the efficacy and safety of everolimus combined with endocrine therapy in patients with hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER-2)-negative advanced breast cancer.

METHODS

The clinical information of 108 patients with HR-positive/HER-2-negative advanced breast cancer, who were admitted to and treated in our hospital from June 2014 to June 2016, was retrospectively analyzed. Of them, 54 patients were treated with everolimus combined with endocrine drugs (Everolimus group), while the other 54 patients underwent endocrine monotherapy (Control group). The clinical response rate and incidence of adverse reactions were compared between the two groups of patients, and the patients were followed up to record survival. Besides, the possible influencing factors for progression-free survival (PFS) were analyzed.

RESULTS

The objective response rate (ORR) was 22.2% and 14.8%, respectively, in everolimus group and the Control group, while the clinical benefit rate (CBR) was 66.7% and 37.0%, respectively, in the two groups. There were statistically significant differences in the CBRs of the first-line and second-line therapies. The majority of adverse reactions were in grade I and II, with lower incidence rates of grade III and IV adverse reactions. The median PFS of the two groups of patients was 7.3±5.6 months and 6.7±5.1 months, respectively. The log-rank test revealed that there was a statistically significant difference in the PFS between the two groups of patients. According to the multivariate regression analysis results, progesterone receptor (PR)+, absence of visceral metastases, and sensitivity to endocrine therapy were the protective prognostic factors for PFS.

CONCLUSION

Everolimus combined with endocrine therapy has significant clinical efficacy in patients with HR-positive/HER-2-negative advanced breast cancer, and can effectively improve the survival of patients with tolerable adverse reactions. PR+, absence of visceral metastases and sensitivity to endocrine therapy are the protective prognostic factors for PFS.

Changes in serum estrogenic activity during neoadjuvant therapy with letrozole and exemestane

The aromatase inhibitors (AIs), letrozole (Femar®/Femara®) and exemestane (Aromasin®), are widely used to treat estrogen receptor (ER) positive breast cancer in postmenopausal patients. In the setting of metastatic breast cancer, these drugs may be used after another causing new responses in selected patients after progressing on the first choice. The precise explanation for this "lack of cross resistance" is still missing. NEOLETEXE is a neoadjuvant, randomized, open-label, cross-over trial. Postmenopausal patients with ER-positive, HER-2 negative, locally advanced breast cancer were enrolled. All patients were randomized to treatment starting with either letrozole or exemestane for at least 2 months followed by another 2 months on the alternative AI. The total estrogenic activities in blood samples were determined using the AroER tri-screen assay developed in the Chen laboratory. Using this highly sensitive assay, estrogenic activity was detected at three time points for all patients. Importantly, a significantly higher total estrogenic activity was found during therapy with exemestane compared to letrozole in 21 out of 26 patients. When letrozole was included in the AroER tri-screen assay, the estrogenic activities in most samples collected during exemestane treatment were further reduced, suggesting that low levels of androgens remained in specimens obtained after exemestane treatment. Our results suggest the AroER tri-screen to be a very sensitive method to estimate the overall estrogen-mediated activity in human samples even during therapy with highly potent aromatase inhibitors. In the present study, serum estrogen activity was significantly higher during exemestane therapy when compared to letrozole therapy.

Antitumor activity of Z-endoxifen in aromatase inhibitor-sensitive and aromatase inhibitor-resistant estrogen receptor-positive breast cancer

BACKGROUND

The tamoxifen metabolite, Z-endoxifen, demonstrated promising antitumor activity in endocrine-resistant estrogen receptor-positive (ER+) breast cancer. We compared the antitumor activity of Z-endoxifen with tamoxifen and letrozole in the letrozole-sensitive MCF7 aromatase expressing model (MCF7AC1), as well as with tamoxifen, fulvestrant, exemestane, and exemestane plus everolimus in a letrozole-resistant MCF7 model (MCF7LR).

METHODS

MCF7AC1 tumor-bearing mice were randomized to control (no drug), letrozole (10 μg/day), tamoxifen (500 μg/day), or Z-endoxifen (25 and 75 mg/kg). Treatment in the letrozole arm was continued until resistance developed. MCF7LR tumor-bearing mice were then randomized to Z-endoxifen (50 mg/kg) or tamoxifen for 4 weeks and tumors harvested for microarray and immunohistochemistry analysis. The antitumor activity of Z-endoxifen in the MCF7LR tumors was further compared in a second in vivo study with exemestane, exemestane plus everolimus, and fulvestrant.

RESULTS

In the MCF7AC1 tumors, both Z-endoxifen doses were significantly superior to control and tamoxifen in reducing tumor volumes at 4 weeks. Additionally, the 75 mg/kg Z-endoxifen dose was additionally superior to letrozole. Prolonged letrozole exposure resulted in resistance at 25 weeks. In MCF7LR tumor-bearing mice, Z-endoxifen significantly reduced tumor volumes compared to tamoxifen, letrozole, and exemestane, with no significant differences compared to exemestane plus everolimus and fulvestrant. Additionally, compared to tamoxifen, Z-endoxifen markedly inhibited ERα target genes, Ki67 and Akt expression in vivo.

CONCLUSION

In endocrine-sensitive and letrozole-resistant breast tumors, Z-endoxifen results in robust antitumor and antiestrogenic activity compared to tamoxifen and aromatase inhibitor monotherapy. These data support the ongoing development of Z-endoxifen.

Effect of Letrozole on sperm parameters, chromatin status and ROS level in idiopathic Oligo/Astheno/Teratozoospermia

BACKGROUND

This study investigates the effect of letrozole on hormone profiles, semen parameters, body mass index (BMI), degree of oxidative stress and sperm chromatin integrity in men with idiopathic oligo/astheno/teratozoospermia (iOAT) and T:E₂ ratio ≤ 10.

MATERIALS AND METHODS

This study is a longitudinal, prospective, interventional and open-labelled clinical trial. Semen samples were collected from 20 iOAT men with low serum testosterone (T) to estradiol (E₂) ratio (T:E₂ ratio ≤ 10). The participants were treated with 2.5 mg letrozole orally per day for 3 months. Then, sperm parameters, hormone profiles, BMI, chromatin integrity and intracellular reactive oxygen species (ROS) level were assessed pre- and post- treatment. The chromatin integrity was evaluated by assessment of DNA fragmentation (with TUNEL assay) and protamine deficiency (with Chromomycin A3, CMA3). Also, the intracellular ROS levels were investigated by 2', 7'-dichlorodihydrofluorescein diacetate (DCFH-DA) staining. Finally, the differences between the parameters evaluated before and after letrozole treatment were analyzed with the t-test and the Wilcoxon signed-rank test.

RESULTS

Sperm concentration, percentage of sperm motility and its normal morphology increased significantly after letrozole treatment. Moreover, serum testosterone level increased but estradiol level decreased significantly following treatment. The mean of T:E2 ratio improved 1600%. Also, letrozole treatment significantly reduced the percentage of sperm TUNEL positivity and sperm CMA3 positivity. While no significant difference was observed between intracellular ROS levels and BMI before and after treatment. Finally, as a notable result, four spontaneous pregnancies (20%) were achieved after treatment.

CONCLUSIONS

Letrozole treatment can effectively increase spontaneous pregnancies by improving sperm parameters and sperm chromatin integrity in men with iOAT and T:E2 ratio ≤ 10.

TRIAL REGISTRATION

Trial registration: IRCT, IRCT20191030045283N1. Registered 16 November 2019 - Retrospectively registered, https://fa.irct.ir/user/trial/43484/view.

Comparative effectiveness of tamoxifen, toremifene, letrozole, anastrozole, and exemestane on lipid profiles in breast cancer patients: A network meta-analysis

BACKGROUND

Adjuvant endocrine therapy is a vital portion of postoperative comprehensive treatment for breast cancer patients. In recent years, studies have shown that endocrine therapy has a certain impact on the serum lipids of breast cancer patients, and the changes of lipid profiles may bring a series of problems. However, very few studies focus on this issue to date. The results of these studies are inconsistent, and the influence of different adjuvant endocrine modalities on lipid profiles still remains controversial. In order to better explore this issue, we conduct this network meta-analysis.

METHOD

The protocol followed preferred reporting items for systematic reviews and meta-analyses protocols. Three main databases (PubMed, Embase, and the Cochrane Library) will be searched systematically for eligible randomized controlled trials without language restriction. In addition, a manual search of the references of relevant published studies will also be considered. Two reviewers will conduct studies selection, data extraction, and risk of bias assessment independently. The primary outcome is the variation of biochemical parameters - the serum lipid profiles (cholesterol, triglyceride, high-density lipoprotein, low low-density lipoprotein).

RESULTS

The results will provide useful information about the side effects of different adjuvant endocrine drugs on lipid profiles in postoperative breast cancer patients (estrogen receptor-positive and/or progesterone receptor-positive).

CONCLUSION

The findings of this study will be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42019129850.

The regulation of the follicular synchronization and sensitivity of rats with PCOS by AMH during prolonged pituitary downregulation

The modified prolonged gonadotropin-releasing hormone agonist (GnRH-a) protocol lessens the ovarian hyperstimulation syndrome (OHSS) effect and improves the clinical pregnancy rate of women with polycystic ovary syndrome (PCOS) compared with the standard long GnRH-a protocol. However, the molecular basis of this process needs to be elucidated. Sprague Dawley (SD) female rats with letrozole-induced PCOS were divided into GnRH-a and blank groups. Rats in the GnRH-a group were given triptorelin for 11 days, whereas those in blank group were given an equal volume of 0.9% NaCl. Meanwhile, the changes in estrus cycle, hormonal profile, ovary index, ovarian histopathology and body weight were measured. The expressions of anti-mullerian hormone (AMH), type II receptor of AMH (AMHRII), and FSH receptor (FSHR) were taken as the indicators of follicular sensitivity. Changes of follicular counting and differences in antral follicle diameter at each stage were evaluated. The number of follicles from primordial to antral stages increased during downregulation and the differences in antral follicle diameter were reduced in the GnRH-a group, whereas no significant difference was found in the blank group. The results of Western blotting and ELISA indicated that the level of AMH in ovarian total protein and serum had a similar dynamic change in the GnRH-a group. The results of immunohistochemistry showed that follicular AMH, AMHRII, and FSHR significantly decreased in the GnRH-a group. Prolonged GnRH-a protocol can improve synchronization and sensitivity of follicular development by balancing the expressions of AMH, AMHRII, and FSHR among follicles at all levels, thereby achieving better therapeutic effect.

Letrozole treatment of pubertal female mice results in activational effects on reproduction, metabolism and the gut microbiome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder in reproductive-aged women that is comprised of two out of the following three features: hyperandrogenism, oligo- or amenorrhea, or polycystic ovaries. In addition to infertility, many women with PCOS have metabolic dysregulation that increases the risk of developing type 2 diabetes, hypertension, and non-alcoholic fatty liver disease. Changes in the gut microbiome are associated with PCOS and gut microbes may be involved in the pathology of this disorder. Since PCOS often manifests in the early reproductive years, puberty is considered to be a critical time period for the development of PCOS. Exposure to sex steroid hormones during development results in permanent, organizational effects, while activational effects are transient and require the continued presence of the hormone. Androgens exert organizational effects during prenatal or early post-natal development, but it is unclear whether androgen excess results in organizational or activational effects during puberty. We recently developed a letrozole-induced PCOS mouse model that recapitulates both reproductive and metabolic phenotypes of PCOS. In this study, we investigated whether letrozole treatment of pubertal female mice exerts organizational or activational effects on host physiology and the gut microbiome. Two months after letrozole removal, we observed recovery of reproductive and metabolic parameters, as well as diversity and composition of the gut microbiome, indicating that letrozole treatment of female mice during puberty resulted in predominantly activational effects. These results suggest that if exposure to excess androgens during puberty leads to the development of PCOS, reduction of androgen levels during this time may improve reproductive and metabolic phenotypes in women with PCOS. These results also imply that continuous letrozole exposure is required to model PCOS in pubertal female mice since letrozole exerts activational rather than organizational effects during puberty.

Therapeutic Efficacy of Melatonin Against Polycystic Ovary Syndrome (PCOS) Induced by Letrozole in Wistar Rat

BACKGROUND AND OBJECTIVES

Polycystic ovary syndrome (PCOS) is a common heterogeneous endocrinological and metabolic disorder in women of reproductive age which leads to infertility/subfertility. The present study was commenced to elucidate the therapeutic efficacy of melatonin in the pathogenesis of letrozole induced polycystic ovary syndrome (PCOS) in Wistar rat.

MATERIALS AND METHODS

Letrozole was administered orally (1 mg kg-1) to induce PCOS condition in Wistar female rats for a period of 2-3 weeks followed by a dose of melatonin (200 µg/100 g b.wt.) to PCOS induced rats. On the completion of experimental period the level of cytokines and expression level of different receptors was assessed.

RESULTS

The PCOs rats showed down regulation in melatonin (MT1 and MT2), estrogen (ER-α) and cytokine (IL-2R and IL-6R) receptors expression and high circulatory level of IL-6 and TNF-α during PCO condition. These anomalies in expression pattern and circulatory level of cytokines were restored following the treatment.

CONCLUSION

Finding of present study showed the role of melatonin supplementation at receptor level and also suggesting a crosstalk between MT1R / MT2R via cytokine IL-2R and IL-6R resulting in modulation of ER-α receptors.