Lasofoxifene as a potential treatment for aromatase inhibitor-resistant ER-positive breast cancer.

BACKGROUND: Breast cancers treated with aromatase inhibitors (AIs) can develop AI resistance, which is often driven by estrogen receptor-alpha (ERα/ESR1) activating mutations, as well as by ER-independent signaling pathways. The breast ER antagonist lasofoxifene, alone or combined with palbociclib, elicited antitumor activities in a xenograft model of ER + metastatic breast cancer (mBC) harboring ESR1 mutations. The current study investigated the activity of LAS in a letrozole-resistant breast tumor model that does not have ESR1 mutations. METHODS: Letrozole-resistant, MCF7 LTLT cells tagged with luciferase-GFP were injected into the mammary duct inguinal glands of NSG mice (MIND model; 6 mice/group). Mice were randomized to vehicle, lasofoxifene ± palbociclib, fulvestrant ± palbociclib, or palbociclib alone 2-3 weeks after cell injections. Tumor growth and metastases were monitored with in vivo and ex vivo luminescence imaging, terminal tumor weight measurements, and histological analysis. The experiment was repeated with the same design and 8-9 mice in each treatment group. RESULTS: Western blot analysis showed that the MCF7 LTLT cells had lower ERα and higher HER2 expressions compared with normal MCF7 cells. Lasofoxifene ± palbociclib, but not fulvestrant, significantly reduced primary tumor growth versus vehicle as assessed by in vivo imaging of tumors at study ends. Percent tumor area in excised mammary glands was significantly lower for lasofoxifene plus palbociclib versus vehicle. Ki67 staining showed decreased overall tumor cell proliferation with lasofoxifene ± palbociclib. The lasofoxifene + palbociclib combination was also associated with significantly fewer bone metastases compared with vehicle. Similar results were observed in the repeat experiment. CONCLUSIONS: In a mouse model of letrozole-resistant breast cancer with no ESR1 mutations, reduced levels of ERα, and overexpression of HER2, lasofoxifene alone or combined with palbociclib inhibited primary tumor growth more effectively than fulvestrant. Lasofoxifene plus palbociclib also reduced bone metastases. These results suggest that lasofoxifene alone or combined with a CDK4/6 inhibitor may offer benefits to patients who have ER-low and HER2-positive, AI-resistant breast cancer, independent of ESR1 mutations.

Ameliorative potential of rosmarinic acid in a rat model of polycystic ovary syndrome: Targeting MCP-1 and VEGF: A histological, immunohistochemical, and biochemical study.

Polycystic ovary syndrome (PCOS) is a multidisciplinary endocrinopathy that affects women of reproductive age. It is characterized by menstrual complications, hyperandrogenism, insulin resistance, and cardiovascular issues. The current research investigated the efficacy of rosmarinic acid in letrozole-induced PCOS in adult female rats as well as the potential underlying molecular mechanisms. Forty female rats were divided into the control group, the rosmarinic acid group (50 mg/kg per orally, po) for 21 days, PCOS group; PCOS was induced by administration of letrozole (1 mg/kg po) for 21 days, and rosmarinic acid-PCOS group, received rosmarinic acid after PCOS induction. PCOS resulted in a marked elevation in both serum luteinizing hormone (LH) and testosterone levels and LH/follicle-stimulating hormone ratio with a marked reduction in serum estradiol and progesterone levels. A marked rise in tumor necrosis factor-α (TNF-α), interleukin-1ß, monocyte chemotactic protein-1, and vascular endothelial growth factor (messenger RNA) in the ovarian tissue was reported. The histological analysis displayed multiple cystic follicles in the ovarian cortex with markedly thin granulosa cell layer, vacuolated granulosa and theca cell layers, and desquamated granulosa cells. Upregulation in the immune expression of TNF-α and caspase-3 was demonstrated in the ovarian cortex. Interestingly, rosmarinic acid ameliorated the biochemical and histopathological changes. In conclusion, rosmarinic acid ameliorates letrozole-induced PCOS through its anti-inflammatory and antiangiogenesis effects.

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.

Estrogen stimulates fetal vascular endothelial growth factor expression and microvascularization.

We recently showed that the ratio of capillaries to myofibers in skeletal muscle, which accounts for 80% of insulin-directed glucose uptake and metabolism, was reduced in baboon fetuses in which estrogen was suppressed by maternal letrozole administration. Since vascular endothelial growth factor (VEGF) promotes angiogenesis, the present study determined the impact of estrogen deprivation on fetal skeletal muscle VEGF expression, capillary development, and long-term vascular and metabolic function in 4- to 8-year-old adult offspring. Maternal baboons were untreated or treated with letrozole or letrozole plus estradiol on days 100-164 of gestation (term = 184 days). Skeletal muscle VEGF protein expression was suppressed by 45% (P < 0.05) and correlated (P = 0.01) with a 47% reduction (P < 0.05) in the number of capillaries per myofiber area in fetuses of baboons in which serum estradiol levels were suppressed 95% (P < 0.01) by letrozole administration. The reduction in fetal skeletal muscle microvascularization was associated with a 52% decline (P = 0.02) in acetylcholine-induced brachial artery dilation and a 23% increase (P = 0.01) in mean arterial blood pressure in adult progeny of letrozole-treated baboons, which was restored to normal by letrozole plus estradiol. The present study indicates that estrogen upregulates skeletal muscle VEGF expression and systemic microvessel development within the fetus as an essential programming event critical for ontogenesis of systemic vascular function and insulin sensitivity/glucose homeostasis after birth in primate offspring.

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.

Letrozole delays acquisition of water maze task in female BALB/c mice: Possible involvement of anxiety.

Letrozole, an aromatase inhibitor preventing estrogen synthesis from testosterone, is used as an adjuvant therapy in estrogen receptor-positive breast cancer patients. However, like other aromatase inhibitors, it induces many side effects, including impaired cognition. Despite its negative effect in humans, results from animal models are inconsistent and suggest that letrozole can either impair or improve cognition. Here, we studied the effects of chronic letrozole treatment on cognitive behavior of adult female BALB/c mice, a relevant animal model for breast cancer studies, to develop an appropriate animal model aimed at testing therapies to mitigate side effects of letrozole. In Morris water maze, letrozole 0.1 mg/kg impaired reference learning and memory. Interestingly, most of the letrozole 0.1 mg/kg-treated mice were able to learn the new platform position in reversal training and performed similar to control mice in a reversal probe test. Results of the reversal test suggest that letrozole did not completely disrupt spatial navigation, but rather delayed acquisition of spatial information. The delay might be related to increased anxiety as suggested by increased thigmotactic behavior during the reference memory training. The learning impairment was water maze-specific since we did not observe impairment in other spatial tasks such as in Y-maze or object location test. In contrast, the dose of 0.3 mg/kg did not have effect on water maze learning and facilitated locomotor habituation and recognition in novel object recognition test. The current study shows that letrozole dose-dependently modulates behavioral response and that its effects are task-dependent.

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.

Gonadotropin upregulates intraovarian calpains-1 and -2 during ovarian follicular recruitment in the SD rat model.

Calpain role has been shown in the cumulus cell-oocyte complexes and, corpus luteum. We investigated the association of calpains-1 and -2 in ovarian folliculogenesis using the Sprague-Dawley (SD) rat model and steroidogenesis in the human granulosa cells (hGCs). We induced PCOS in 42-day-old SD rats by letrozole oral gavage for 21 days. Premature ovarian failure (POF) was induced in 21-day-old SD rats by 4-vinylcyclohexene diepoxide (VCD). Ovulation and ovarian hyperstimulatory (OHS) syndrome were induced by pregnant mare gonadotropin (PMSG) + human chorionic gonadotropin (hCG) treatments in 21 days SD rats, respectively. Steroidogenesis is stimulated in human granulosa cells (hGCs) by forskolin and the response of 17-beta-estradiol (E2) on calpains expression was checked in hGCs. The protein expression by immunoblotting and activity by biochemical assay of calpains-1 and -2 showed an oscillating pattern in the ovarian cycle. PMSG-induced follicular recruitment showed upregulation of calpains-1 and -2, but with no change during ovarian function cessation (POF). Upregulated calpain-2 expression and calpain activity was found in the hCG +PMSG-induced ovulation. Letrozole-induced PCOS showed downregulation of calpain-1, but upregulation of calpain-2. PMSG+hCG-induced OHS led to the upregulation of calpain-1. Letrozole and metformin separately increased the expression level of calpains-1 and -2 in the hGCs during luteinization. In conclusion, the expression levels of calpains -1 and -2 are increased with ovarian follicular recruitment by PMSG and calpain-1 is decreased in the PCOS condition, and letrozole and metformin upregulate the expression of calpains-1 and -2 during luteinization in the hGCs possibly via E2 action.

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.

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.

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.

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.

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.

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.

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.

Synergistic action of carvedilol and clomiphene in mitigating the behavioral phenotypes of letrozole-model of PCOS rats by modulating the NRF2/NFKB pathway.

INTRODUCTION: Psychiatric and cognitive impairment has been observed in premenopausal women with a hormonal disorder called polycystic ovary syndrome (PCOS). This study aimed to explore the possibility of combining pharmacological agents: Carvedilol and Clomiphene citrate, with antiestrogenic, antioxidant and anti-inflammatory properties in letrozole-induced PCOS rats. METHODS: PCOS was induced in rats by the administration of letrozole (1 mg/kg) daily for 21 days. They were subsequently divided into four groups, each receiving either the vehicle or Clomiphene citrate (1 mg/kg) or Carvedilol or a combination of Clomiphene citrate and Carvedilol, respectively from days 22-36. Neurobehavioral studies were conducted on day 35 (Elevated plus maze and Y maze) and day 36 (Novel object recognition). The serum levels of the antioxidants Superoxide dismutase, Catalase, Interleukin 1B (IL-1B), and the gene expression of nuclear factor-erythroid factor 2-related factor 2 (Nrf2), Nuclear Factor k-Beta (NFKB), and acetylcholine esterase in the frontal brain homogenate was determined. RESULT: Both Carvedilol and the combination therapy reversed the anxiety-like behavior, while Clomiphene citrate and the combination therapy ameliorated the spatial and non-spatial memory impairment observed in PCOS rats. Carvedilol, Clomiphene citrate, and the combination therapy increased the serum concentration of SOD and Catalase and decreased the serum concentration of IL-1B. The combination therapy up-regulated the NRF-2, NFKB, and acetylcholine esterase gene expression. CONCLUSION: Study showed that the combination of carvedilol and clomiphene citrate has anxiolytic potential and improved cognitive functions in PCOS rats. This might have been achieved by carvedilol and clomiphene citrate's ability to modulate the cholinergic system and the Nrf2 pathway while downregulating the NFκB signaling pathway.

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 17ß-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.

Novel Therapeutic Combination Targets the Growth of Letrozole-Resistant Breast Cancer through Decreased Cyclin B1.

As breast cancer cells transition from letrozole-sensitive to letrozole-resistant, they over-express epidermal growth factor receptor (EGFR), mitogen-activated protein kinase (MAPK), and human epidermal growth factor receptor 2 (HER2) while acquiring enhanced motility and epithelial-to-mesenchymal transition (EMT)-like characteristics that are attenuated and reversed by glyceollin treatment, respectively. Interestingly, glyceollin inhibits the proliferation and tumor progression of triple-negative breast cancer (TNBC) and estrogen-independent breast cancer cells; however, it is unlikely that a single phytochemical would effectively target aromatase-inhibitor (AI)-resistant metastatic breast cancer in the clinical setting. Since our previous report indicated that the combination of lapatinib and glyceollin induced apoptosis in hormone-dependent AI-resistant breast cancer cells, we hypothesized that combination therapy would also be beneficial for hormone independent letrozole-resistant breast cancer cells (LTLT-Ca) compared to AI-sensitive breast cancer cells (AC-1) by decreasing the expression of proteins associated with proliferation and cell cycle progression. While glyceollin + lapatinib treatment caused comparable inhibitory effects on the proliferation and migration in both cell lines, combination treatment selectively induced S and G2/M phase cell cycle arrest of the LTLT-Ca cells, which was mediated by decreased cyclin B1. This phenomenon may represent a unique opportunity to design novel combinatorial therapeutic approaches to target hormone-refractory breast tumors.

Macrophages in juvenile pig testis: Link with increase in Sertoli cells induced by oestradiol suppression.

Macrophage presence and location were evaluated in juvenile boar testes at the end of the first wave of Sertoli cell proliferation. Macrophage presence was compared in littermate boars treated with letrozole, a treatment which extended this first wave of proliferation beyond the sampling timepoint. Macrophages were identified as the CD68 positive cells following immunohistochemical labelling of paraffin sections and parenchymal macrophages enumerated. Macrophages present in a layer beneath the tunica albuginea received a score based on density and thickness of this layer. Density within the testicular parenchyma was highly variable in vehicle-treated boars (>100-fold) and did not differ from that observed in the letrozole-treated littermates. However, the macrophage layer beneath the tunica albuginea was denser and thicker in the letrozole-treated animals than in their vehicle-treated littermates. This suggests that macrophages might be involved in the letrozole-induced prolongation of Sertoli cell proliferation.