Metformin: direct inhibition of rat ovarian theca-interstitial cell proliferation

Dorsomorphin inhibits AMPK, upregulates Wnt and Foxo genes and promotes the activation of dormant follicles

AMPK is a well-known energy sensor regulating cellular metabolism. Metabolic disorders such as obesity and diabetes are considered detrimental factors that reduce fecundity. Here, we show that pharmacologically induced in vitro activation (by metformin) or inhibition (by dorsomorphin) of the AMPK pathway inhibits or promotes activation of ovarian primordial follicles in cultured murine ovaries and human ovarian cortical chips. In mice, activation of primordial follicles in dorsomorphin in vitro-treated ovaries reduces AMPK activation and upregulates Wnt and FOXO genes, which, interestingly, is associated with decreased phosphorylation of β-catenin. The dorsomorphin-treated ovaries remain of high quality, with no detectable difference in reactive oxygen species production, apoptosis or mitochondrial cytochrome c oxidase activity, suggesting safe activation. Subsequent maturation of in vitro-treated follicles, using a 3D alginate cell culture system, results in mature metaphase eggs with protruding polar bodies. These findings demonstrate that the AMPK pathway can safely regulate primordial follicles by modulating Wnt and FOXO genes, and reduce β-catenin phosphorylation.

Efficacy of Bee Products (Anzer Honey, Pollen and Propolis) in Detection and Healing of Damage Induced by Antidiabetic Drug Vildagliptin/Metformin Hydrochloride in Healthy Human Pancreatic Cells: Cytotoxic, Genotoxic and Biochemical Studies

BACKGROUND AND OBJECTIVE

Although drugs are powerful therapeutic agents, they have a range of side effects. These side effects are sometimes cellular and not clinically noticeable. Vildagliptin/metformin hydrochloride is one of the most widely used oral antidiabetic drugs with two active ingredients. In this study, we investigated its harmful effects on the metabolic activation system in healthy human pancreatic cells "hTERT-HPNE", and we aimed to improve these harmful effects by natural products. To benefit from the healing effect, we used the unique natural products produced by the bees of the Anzer Plateau in the Eastern Black Sea Region of Turkey.

METHODS

Cytotoxic and genotoxic effects of the drug were investigated by different tests, such as MTT, flow cytometry-apoptosis and comet assays. Anzer honey, pollen and propolis were analyzed by gas chromatography/mass spectrometry (G/C-MS). A total of 19 compounds were detected, constituting 99.9% of the samples.

RESULTS

The decrease in cell viability at all drug concentrations was statistically significant compared to the negative control (P<0.05). A statistically significant decrease was detected in the apoptosis caused by vildagliptin/metformin hydrochloride with the supplementation of Anzer honey, pollen and propolis in hTERT-HPNE cells (P<0.05).

CONCLUSION

This study can contribute to other studies testing the healing properties of natural products against the side effects of oral antidiabetics in human cells. In particular, Anzer honey, pollen and propolis can be used as additional foods to maintain cell viability and improve heal damage and can be evaluated against side effects in other drug studies.

Metformin: Activation of 5′ AMP-activated protein kinase and its emerging potential beyond anti-hyperglycemic action

Metformin is a plant-based drug belonging to the class of biguanides and is known to treat type-2 diabetes mellitus (T2DM). The drug, combined with controlling blood glucose levels, improves the body’s response to insulin. In addition, trials have identified the cardioprotective potential of metformin in the diabetic population receiving the drug. Activation of 5′ AMP-activated protein kinase (AMPK) is the major pathway for these potential beneficial effects of metformin. Historically, much emphasis has been placed on the potential indications of metformin beyond its anti-diabetic use. This review aims to appraise other potential uses of metformin primarily mediated by the activation of AMPK. We also discuss various mechanisms, other than AMPK activation, by which metformin could produce beneficial effects for different conditions. Databases including PubMed/MEDLINE and Embase were searched for literature relevant to the review’s objective. Reports from both research and review articles were considered. We found that metformin has diverse effects on the human body systems. It has been shown to exert anti-inflammatory, antioxidant, cardioprotective, metabolic, neuroprotective, anti-cancer, and antimicrobial effects and has now even been identified as effective against SARS-CoV-2. Above all, the AMPK pathway has been recognized as responsible for metformin’s efficiency and effectiveness. Owing to its extensive potential, it has the capability to become a part of treatment regimens for diseases apart from T2DM.

hUCMSCs reduce theca interstitial cells apoptosis and restore ovarian function in premature ovarian insufficiency rats through regulating NR4A1-mediated mitochondrial mechanisms

BACKGROUND

Human umbilical cord mesenchymal stem cells (hUCMSCs, retrospectively registered) have a lot of promise for treating theca interstitial cells(TICs) dysfunction in premature ovarian insufficiency (POI). The mechanisms, however, are still unknown.

METHODS

To examine the therapeutic and find the cause, we used both in vivo cisplatin-induced POI rat model and in vitro TICs model. HUCMSCs were injected into the tail veins of POI rats in an in vivo investigation. Then, using ELISA, HE staining, TUNEL apoptosis test kit, immunohistochemistry and western blot, researchers examined hormonal levels, ovarian morphology, TICs apoptosis, NR4A1 and Cyp17a1 in response to cisplatin treatment and hUCMSCs. TICs were obtained from the ovaries of rats and treated with the cisplatin, hUCMSCs supernatant, and the antagonist of NR4A1--DIM-C-pPhOH. ELISA, immunofluorescence, flow cytometry, JC-1 labeling and western blot analysis were used to detect T levels, Cyp17a1, NR4A1, and the anti-apoptotic protein Bcl-2, as well as pro-apoptotic proteins Bax, caspase-9, caspase-3, and cytochrome C(cytc).

RESULTS

We discovered that hUCMSCs restored the ovarian function, particularly TICs function based on measures of Cyp17a1 and T expression. NR4A1 was found in ovarian TICs of each group and NR4A1 expression was lower in the POI rats but higher following hUCMSCs therapy. The apoptosis of TICs generated by cisplatin was reduced after treatment with hUCMSCs. In vitro, NR4A1 was expressed in the nucleus of TICs, and NR4A1 as well as phospho-NR4A1 were decreased, following the apoptosis of TICs was emerged after cisplatin treatment. Interestingly, the localization of NR4A1 was translocated from the nucleus to the cytoplasm due to cisplatin. HUCMSCs were able to boost NR4A1 and phospho-NR4A1 expression while TICs' apoptosis and JC-1 polymorimonomor fluorescence ratios reduced. Furthermore, Bcl-2 expression dropped following cisplatin treatment, whereas Bax, cytc, caspase-9, and caspase-3 expression rose; however, hUCMSCs treatment reduced their expression. In addition, DIM-C-pPhOH had no effect on the NR4A1 expression, but it did increase the expression of apoptosis-related factors such as Bax, cytc, caspase-9, and caspase-3, causing the apoptosis of TICs.

CONCLUSIONS

These data show that hUCMSCs therapy improves ovarian function in POI rats by inhibiting TICs apoptosis through regulating NR4A1 -mediated mitochondrial mechanisms.

The Effect of RBP4 on microRNA Expression Profiles in Porcine Granulosa Cells

Simple Summary

Retinol binding protein 4 (RBP4), mainly secreted by the liver and adipocytes, is a transporter of vitamin A. RBP4 has been shown to be involved in several pathophysiological processes, such as polycystic ovary syndrome (PCOS), obesity, insulin resistance, and cardiovascular risk. However, the role of RBP4 in mammalian follicular granulosa cells (GCs) remains largely unknown. To characterize the molecular pathways associated with the effects of RBP4 on GCs, we used sRNA deep sequencing to detect differential microRNA (miRNA) expression in GCs overexpressing RBP4. A total of 17 miRNAs were significantly different between the experimental and control groups. Our results support the notion that several miRNAs are involved in important biological processes associated with folliculogenesis and pathogenesis. These results will be useful for further studies investigating the role of RBP4 in porcine GCs.

Abstract

Retinol binding protein 4 (RBP4) is a transporter of vitamin A that is secreted mainly by hepatocytes and adipocytes. It affects diverse pathophysiological processes, such as obesity, insulin resistance, and cardiovascular diseases. MicroRNAs (miRNAs) have been reported to play indispensable roles in regulating various developmental processes via the post-transcriptional repression of target genes in mammals. However, the functional link between RBP4 and changes in miRNA expression in porcine granulosa cells (GCs) remains to be investigated. To examine how increased expression of RBP4 affects miRNA expression, porcine GCs were infected with RBP4-targeted lentivirus for 72 h, and whole-genome miRNA profiling (miRNA sequencing) was performed. The sequencing data were validated using real-time quantitative polymerase chain reaction (RT-qPCR) analysis. As a result, we obtained 2783 known and 776 novel miRNAs. In the experimental group, 10 and seven miRNAs were significantly downregulated and upregulated, respectively, compared with the control group. Ontology analysis of the biological processes of these miRNAs indicated their involvement in a variety of biological functions. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses indicated that these miRNAs were involved mainly in the chemokine signaling pathway, peroxisome proliferators-activated receptors (PPAR) signaling pathway, insulin resistance pathway, nuclear factor-kappa B(NF-kappa B) signaling pathway, and steroid hormone biosynthesis. Our results indicate that RBP4 can regulate the expression of miRNAs in porcine GCs, with consequent physiological effects. In summary, this study profiling miRNA expression in RBP4-overexpressing porcine GCs provides an important reference point for future studies on the regulatory roles of miRNAs in the porcine reproductive system.

Energy sensors and reproductive hypothalamo-pituitary ovarian axis (HPO) in female mammals: Role of mTOR (mammalian target of rapamycin), AMPK (AMP-activated protein kinase) and SIRT1 (Sirtuin 1)

In female, energy metabolism influences reproductive function by modulating the Hypothalamic Pituitary Ovarian axis including the hypothalamic GnRH neuronal network, the pituitary gonadotropin secretion and the ovarian follicle growth and steroidogenesis. Several hormones and neuropeptides or metabolites are important signals between energy balance and reproduction. These energy sensors mediate their action on reproductive cells through specific kinases or signaling pathways. This review focuses on the role of three main enzymes-specifically, mTOR, AMPK, and SIRT1 at the hypothalamic pituitary and ovarian axis in normal female fertility and then we discuss their possible involvement in some women reproductive disorders known to be associated with metabolic complications, such as polycystic ovary syndrome (PCOS) and premature ovarian failure (POF).

Irisin induces trophoblast differentiation via AMPK activation in the human placenta

Irisin, an adipokine, regulates differentiation and phenotype in various cell types including myocytes, adipocytes, and osteoblasts. Circulating irisin concentration increases throughout human pregnancy. In pregnancy disorders such as preeclampsia and gestational diabetes mellitus, circulating irisin levels are reduced compared to healthy controls. To date, there are no data on the role and molecular function of irisin in the human placenta or its contribution to pathophysiology. Aberrant trophoblast differentiation is involved in the pathophysiology of preeclampsia. The current study aimed to assess the molecular effects of irisin on trophoblast differentiation and function. First-trimester placental explants were cultured and treated with low (10 nM) and high (50 nM) physiological doses of irisin. Treatment with irisin dose-dependently increased both in vitro placental outgrowth (on Matrigel™) and trophoblast cell-cell fusion. Adenosine monophosphate-activated protein kinase (AMPK) signaling, an important regulator of cellular energy homeostasis that is involved in trophoblast differentiation and pathology, was subsequently investigated. Here, irisin exposure induced placental AMPK activation. To determine the effects of irisin on trophoblast differentiation, two trophoblast-like cell lines, HTR-8/SVneo and BeWo, were treated with irisin and/or a specific AMPK inhibitor (Compound C). Irisin-induced AMPK phosphorylation in HTR-8/SVneo cells. Additionally, as part of the differentiation process, integrin switching from α6 to α1 occurred as well as increased invasiveness. Overall, irisin promoted differentiation in villous and extravillous cell-based models via AMPK pathway activation. These findings provide evidence that exposure to irisin promotes differentiation and improves trophoblast functions in the human placenta that are affected in abnormal placentation.

Ovarian morphology is associated with insulin resistance in women with polycystic ovary syndrome: a cross sectional study

Background

Polycystic ovary syndrome (PCOS) is a very common disorder well known to be associated with insulin resistance and metabolic disease. Insulin resistance is likely involved in the promotion of the PCOS reproductive phenotype and may mediate some of the ovarian morphology seen in the disorder. The phenotype of each individual woman with PCOS can vary widely as can her metabolic risk.

Methods

This is a cross-sectional study of patients seen in a multidisciplinary PCOS clinic at the University of California at San Francisco between 2006 and 2014.

All participants underwent systematic evaluation with anthropometric measurements, comprehensive skin exam, transvaginal ultrasound and laboratory studies at the time of their initial visit to the clinic. Serum samples were stored and androgen studies were carried out on all stored samples at the University of Virginia. Logistic regression was employed to evaluate the association between ovarian volume or follicle number and metabolic parameters (fasting insulin, HOMA-IR, fasting glucose, 2 h glucose, waist circumference) and hyperandrogenism (free testosterone, total testosterone, DHEAS, acanthosis nigricans), controlling for age.

Results

Three-hundred thirteen patients seen during the study period met Rotterdam criteria for PCOS and had sufficient measurements for inclusion in our analysis. The odds ratio of elevated HOMA-IR for patients with a maximum ovarian volume >10 cc was 1.9 compared to those with a maximum ovarian volume of ≤10 cc (95% CI 1.0–3.4). The odds ratio of abnormal fasting insulin for patients with higher ovarian volume was 1.8 (95% CI 1.0–3.4) compared with those with lower ovarian volume. Follicle number was not significantly associated with any metabolic parameters.

Conclusions

Increased ovarian volume is associated with markers of insulin resistance in PCOS. In concordance with prior studies, we did not find follicle number to be predictive of metabolic risk. Ovarian volume may serve as a useful tool to aid clinicians in their risk stratification and counseling of patients with PCOS.

Insulin signalling and glucose transport in the ovary and ovarian function during the ovarian cycle

Data derived principally from peripheral tissues (fat, muscle and liver) show that insulin signals via diverse interconnecting intracellular pathways and that some of the major intersecting points (known as critical nodes) are the IRSs (insulin receptor substrates), PI3K (phosphoinositide kinase)/Akt and MAPK (mitogen-activated protein kinase). Most of these insulin pathways are probably also active in the ovary and their ability to interact with each other and also with follicle-stimulating hormone (FSH) and luteinizing hormone (LH) signalling pathways enables insulin to exert direct modulating influences on ovarian function. The present paper reviews the intracellular actions of insulin and the uptake of glucose by ovarian tissues (granulosa, theca and oocyte) during the oestrous/menstrual cycle of some rodent, primate and ruminant species. Insulin signals through diverse pathways and these are discussed with specific reference to follicular cell types (granulosa, theca and oocyte). The signalling pathways for FSH in granulosa cells and LH in granulosa and theca cells are summarized. The roles of glucose and of insulin-mediated uptake of glucose in folliculogenesis are discussed. It is suggested that glucose in addition to its well-established role of providing energy for cellular function may also have insulin-mediated signalling functions in ovarian cells, involving AMPK (AMP-dependent protein kinase) and/or hexosamine. Potential interactions of insulin signalling with FSH or LH signalling at critical nodes are identified and the available evidence for such interactions in ovarian cells is discussed. Finally the action of the insulin-sensitizing drugs metformin and the thiazolidinedione rosiglitazone on follicular cells is reviewed.

Stimulation of ovarian follicle growth after AMPK inhibition

Previous studies showed that the protein kinase B (Akt)–mammalian target of rapamycin (mTOR) and Hippo signaling Yes-associated protein (YAP) pathways play important roles in promoting follicle growth. Additionally, other studies demonstrated that 5′ adenosine monophosphate-activated protein kinase (AMPK) is an upstream regulatory element of mTOR and YAP. Here, we used AMPK inhibitor (Compound C) toin vitrocultured ovaries from 10-day-old mice followed byin vivografting into adult hosts or toin situtreated ovaries of 3-week-old mice by intrabursal injection followed by gonadotropin stimulation. We found that the phosphorylation of ovarian mTOR and downstream proteins (ribosomal protein S6 (S6) and eukaryotic translation initiation factor 4B (eIF4B)) was upregulated following Compound C administration, whereas tuberous sclerosis complex 2 (TSC2) phosphorylation was downregulated. Additionally, treatment with Compound C increased hypoxia-inducible factor 1-alpha (Hif1a), vascular endothelial growth factor A (Vegfa), VEGF receptor 2 (Vegfr2) and connective tissue growth factor (Ctgf) mRNA levels. Furthermore, treatment of 10-day-old mice with Compound C promoted the growth of preantral and antral follicles accompanied by enhanced angiogenesis.In situintrabursal injection with Compound C, followed by controlled ovarian hyperstimulation, increased the number of ovulated oocytes in 3-week-old mice, and these oocytes could be successfully fertilized, leading to the delivery of healthy pups. Our results demonstrated that treatment with AMPK inhibitor resulted in the activation of the mTOR signaling pathway, increases inCtgfexpression in mouse ovaries, stimulation of follicle development and promotion of ovarian angiogenesis for ovary growth.

Chinese Herbal Medicine for the Optimal Management of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a complex heterogeneous disorder characterized by androgen excess and ovulatory dysfunction; it is now known to be closely linked to metabolic syndrome. Recent research suggests that insulin resistance plays an important role in the pathogenesis of PCOS which may lead to the excessive production of androgens by ovarian theca cells. Currently there is no single drug that can treat both the reproductive and metabolic complications of the disorder. Existing pharmaceutical agents such as hormonal therapies have been associated with side effects and are not appropriate for PCOS women with infertility. Additionally, insulin sensitizing agents useful for treating the metabolic abnormalities in PCOS have limited efficacy for treating reproductive aspects of the disorder. Chinese herbal medicines have a long history of treating gynaecological problems and infertility and therefore may be a novel approach to the treatment of PCOS. Current research demonstrates that the compounds isolated from herbs have shown beneficial effects for PCOS and when combined in an herbal formula can target both reproductive and metabolic defects simultaneously. Therefore, further investigation into Chinese herbal medicine in the treatment of PCOS is warranted.

Intravaginal administration of metformin hydrochloride loaded cationic niosomes amalgamated with thermosensitive gel for the treatment of polycystic ovary syndrome: In vitro and in vivo studies

BACKGROUND AND OBJECTIVE

Metformin hydrochloride (MTF-HCl) is extensively recommended by physicians for the treatment of polycystic ovary syndrome (PCOS). Mechanistically, MTF-HCl activates AMP-dependent kinase-α (AMPK-α) pathway to decrease the glucose production, enhances fatty acid oxidation and elevates the uptake of glucose in tissues. However, despite favourable physicochemical properties, oral administration of MTF-HCl is associated with impaired bioavailability (50-60%), lactic-acidosis and frequent dosing (500mg 2-3 times a day) in PCOS that ultimately influence the patient compliance. Therefore, in present investigation, MTF-HCl loaded unmodified and cationic small unilamellar niosomes were separately amalgamated with thermosensitive gel (MTF-HCl-SUNs-Gel and MTF-HCl-C-SUNs-Gel) for the treatment of PCOS through vaginal route of administration.

METHODS AND RESULTS

MTF-HCl-SUNs and MTF-HCl-C-SUNs were separately prepared by reverse phase evaporation method. The nanovesicle size and zeta-potential of MTF-HCl-C-SUNs were measured to be 210.3±14.8-nm (P<0.05) and +8.7±2.7-mV (P<0.001), significantly higher than 198.5±20.3-nm and -16.6±3.9-mV of MTF-HCl-SUNs, respectively. Moreover, promising results of in vitro characterization parameters like gelation time, gelling temperature, viscosity analysis, percent mucoadhesiveness and drug release of MTF-HCl-C-SUNs-Gel and MTF-HCl-SUNs-Gel ensured the candidature of tailored gels for further in vivo investigations. In this way, treatment of PCOS rats under scheduled dose-dosage regimen with oral MTF-HCl solution, intravaginal MTF-HCl-SUNs-Gel and intravaginal MTF-HCl-C-SUNs-gel exhibited remarkable alterations, recruitment and development of normal follicles in addition to normalization of level of various hormones in PCOS.

CONCLUSION

In conclusion, MTF-C-SUNs-Gel has paved the way for developing intravaginal dosage form of MTF-HCl for the treatment of PCOS.

A possible role for AMP-activated protein kinase activated by metformin and AICAR in human granulosa cells

BACKGROUND

Women with polycystic ovary syndrome (PCOS) are generally insulin- resistant and are consequently often treated with metformin. We investigated the effect of metformin and AICAR on the AMP-activated protein kinase (AMPK) pathway.

METHODS

We evaluated the effects of 5-amino-imidazole-4-carboxyamide-1- beta-D-ribofuranoside (AICAR) and metformin on tumor necrosis factor (TNF)-alpha- stimulated chemokine production in human granulosa cells. The phosphorylations of AMPK, I-kappaB, 4E-BP-1, p70S6K were analyzed by western immunoblotting.

RESULTS

AICAR and metformin markedly reduced the IL-8 and GROalpha production induced by TNF-alpha. AICAR and metformin also reduced the TNF-alpha-induced phosphorylation of I-kappaB. The phosphorylations of I-kappaB, 4EBP-1, p70S6K were inhibited via an AMPK-dependent signal transduction.

CONCLUSIONS

These results suggest that metformin promotes granulosa cell function by reducing a TNF-alpha- and chemokine-mediated inflammatory reaction through an AMPK-dependent pathway. These finding may have implications for metformin's actions during the treatment of PCOS with metformin.

Diabetes mellitus as a novel risk factor for gastrointestinal malignancies

Evidence of an emerging etiologic link between diabetes mellitus and several gastrointestinal malignancies is presented. Although a correlation between pancreatic cancer and diabetes mellitus has long been suspected, the potential role diabetes mellitus plays in the pathogenicity of both hepatocellular carcinoma and colon cancer is becoming increasingly well defined. Further supporting the prospect of etiologic linkage, the association of diabetes mellitus with colon cancer is consistently demonstrated to be independent of obesity. An increasing incidence of diabetes and obesity in the United States has led to a recent surge in incidence of hepatocellular cancer on the background of nonalcoholic fatty liver disease, and this disease is expected to commensurately grow in incidence. Widespread recognition of this emerging risk factor may lead to a change in screening practices. Although the mechanisms underlying the correlation are still under investigation, the role of insulin, the insulin-like growth factor-I, and related binding and signaling pathways as regulators of cell growth and cell proliferation are implicated in carcinogenesis and tumor growth. The potential role of metformin and other medications for diabetes mellitus in the chemoprevention, carcinogenesis, and treatment of gastrointestinal malignancies is also presented.

Impact of metformin on reproductive tissues: an overview from gametogenesis to gestation

Metformin is an oral anti-hyperglycemic drug that acts as an insulin sensitizer in the treatment of diabetes mellitus type 2. It has also been widely used in the treatment of polycystic ovary syndrome (PCOS) and gestational diabetes. This drug has been shown to activate a protein kinase called 5' AMP-activated protein kinase or AMPK. AMPK is present in many tissues making metformin's effect multi factorial. However as metformin crosses the placenta, its use during pregnancy raises concerns regarding potential adverse effects on the mother and fetus. The majority of reports suggest no significant adverse effects or teratogenicity. However, disconcerting reports of male mouse offspring that were exposed to metformin in utero that present with a reduction in testis size, seminiferous tubule size and in Sertoli cell number suggest that we do not understand the full suite of effects of metformin. In addition, recent molecular evidence is suggesting an epigenetic effect of metformin which could explain some of the long-term effects reported. Nevertheless, the data are still insufficient to completely confirm or disprove negative effects of metformin. The aims of this review are to provide a summary of the safety of metformin in various aspects of sexual reproduction, the use of metformin by gestating mothers, and its possible side-effects on offspring from women who are administered metformin during pregnancy.

Effect of metformin on the human T98G glioblastoma multiforme cell line

Metformin is a guanidine derivative found in Galega officinalis that is commonly used to treat diabetes mellitus. The mechanism of action of metformin involves regulation of the adenosine monophosphate-activated protein kinase/mammalian target of rapamycin signaling pathway, which is implicated in the control of protein synthesis and cell proliferation. This led to the hypothesis that metformin reduces the risk of cancer and slows tumor growth. Thus, in the present study, the effectiveness of metformin as an antiglioma agent was evaluated using the human T98G glioblastoma multiforme cell line. The viability of the T98G cells was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis was monitored by measuring caspase-3 levels, as well as by terminal deoxynucleotidyl transferase dUTP nick end labeling and staining with acridine orange and ethidium bromide. The results demonstrate that metformin reduced cell viability and caused apoptotic morphological changes in the T98G cells. Furthermore, the caspase-3 levels in the metformin-treated T98G cells were higher than those in the control cells. Metformin induced apoptosis in the T98G cell line in a concentration-dependent manner. Metformin may provide an important contribution to the treatment of glioblastoma multiforme.

Effect of berberine on insulin resistance in women with polycystic ovary syndrome: study protocol for a randomized multicenter controlled trial

BACKGROUND

Insulin resistance and hyperinsulinemia play a key role in the pathogenesis of polycystic ovary syndrome (PCOS), which is characterized by hyperandrogenism, ovulatory dysfunction, and presence of polycystic ovaries on pelvic scanning. Insulin resistance is significantly associated with the long-term risks of metabolic syndrome and cardiovascular disease. Berberine has effects on insulin resistance but its use in women with PCOS has not been fully investigated. In this paper, we present a research design evaluating the effects of berberine on insulin resistance in women with PCOS.

METHODS/DESIGN

This is a multicenter, randomized, placebo-controlled and double-blind trial. A total of 120 patients will be enrolled in this study and will be randomized into two groups. Berberine or placebo will be taken orally for 12 weeks. The primary outcome is the whole body insulin action assessed with the hyperinsulinemic-euglycemic clamp.

DISCUSSION

We postulate that women with PCOS will have improved insulin resistance following berberine administration.

TRIAL REGISTRATION

This study is registered at ClinicalTrials.gov, NCT01138930.

Stimulatory effect of insulin on theca-interstitial cell proliferation and cell cycle regulatory proteins through MTORC1 dependent pathway

The present study examined the effect of insulin-mediated activation of the mammalian target of rapamycin complex 1 (MTORC1) signaling network on the proliferation of primary culture of theca-interstitial (T-I) cells. Our results show that insulin treatment increased proliferation of the T-I cells through the MTORC1-dependent signaling pathway by increasing cell cycle regulatory proteins. Inhibition of ERK1/2 signaling caused partial reduction of insulin-induced phosphorylation of RPS6KB1 and RPS6 whereas inhibition of PI3-kinase signaling completely blocked the insulin response. Pharmacological inhibition of MTORC1 with rapamycin abrogated the insulin-induced phosphorylation of EIF4EBP1, RPS6KB1 and its downstream effector, RPS6. These results were further confirmed by demonstrating that knockdown of Mtor using siRNA reduced the insulin-stimulated MTORC1 signaling. Furthermore, insulin-stimulated T-I cell proliferation and the expression of cell cycle regulatory proteins CDK4, CCND3 and PCNA were also blocked by rapamycin. Taken together, the present studies show that insulin stimulates cell proliferation and cell cycle regulatory proteins in T-I cells via activation of the MTORC1 signaling pathway.