The antidiabetic drug metformin inhibits uterine leiomyoma cell proliferation via an AMP-activated protein kinase signaling pathway

Black cohosh efficacy and safety for menopausal symptoms. The Spanish Menopause Society statement

OBJECTIVE

The increasing interest in Western countries regarding phytotherapy use to treat menopause-related symptoms has led the Spanish Menopause Society (AEEM) to update its position statement performed in 2009 on the role of black cohosh (Cimicifuga racemosa) for the treatment of menopausal symptoms.

MATERIAL AND METHODS

A panel of experts from both clinical and research backgrounds were assembled to investigate the best available evidence. Selected studies were obtained by an electronic search, including the Internet search engines MEDLINE-Pubmed (1997-December 2021) and the Cochrane Controlled Trials Register.

RESULTS

Most of the well-designed studies published in recent years have been conducted with the isopropanolic extract of black cohosh/C. racemosa. The most common dose is 40 mg/day capable of achieving a significant reduction in hot flushes (particularly in women with intense hot flushes) and an improvement in mood. Used at the recommended doses, C. racemose produces no significant adverse reactions.

CONCLUSION

Black cohosh is an effective and safe treatment option for the relieving of vasomotor symptoms. Finally, further clinical trials with sufficient patient enrollment and longer study follow-up are needed.

Effects of hyperglycemia on the progression of tumor diseases

Malignant tumors are often multifactorial. Epidemiological studies have shown that hyperglycemia raises the prevalence and mortality of certain malignancies, like breast, liver, bladder, pancreatic, colorectal, endometrial cancers. Hyperglycemia can promote the proliferation, invasion and migration, induce the apoptotic resistance and enhance the chemoresistance of tumor cells. This review focuses on the new findings in the relationship between hyperglycemia and tumor development.

Metformin use is associated with a lower risk of uterine leiomyoma in female type 2 diabetes patients

BACKGROUND

Whether metformin may reduce the risk of uterine leiomyoma in type 2 diabetes patients has not been investigated. This retrospective cohort study compared the risk of uterine leiomyoma in ever versus never users of metformin.

METHODS

Female patients with new-onset type 2 diabetes during 1999-2005 were enrolled from the reimbursement database of Taiwan's National Health Insurance and followed up from 1 January 2006 until 31 December 2011. Analyses were conducted in a propensity score (PS) matched-pair cohort of 10,998 ever users and 10,998 never users of metformin. Hazard ratios were estimated by Cox regression incorporated with the inverse probability of treatment weighting using the PS.

RESULTS

A total of 321 never users and 162 ever users developed uterine leiomyoma during follow up, with respective incidence of 704.65 and 329.82 per 100,000 person-years. The overall hazard ratio was 0.467 (95% confidence interval: 0.387-0.564). The hazard ratios for the first (<23.3 months), second (23.3-53.1 months), and third (>53.1 months) tertiles of cumulative duration were 0.881 (0.685-1.132), 0.485 (0.367-0.642), and 0.198 (0.134-0.291), respectively; and were 0.751 (0.576-0.980), 0.477 (0.360-0.632), and 0.277 (0.198-0.386), respectively, for the first (<655,000 mg), second 655,000-1,725,500 mg), and third (>1,725,500) tertiles of cumulative dose. Sensitivity analyses after excluding users of sulfonylurea, users of estrogen, users of insulin, users of incretin-based therapies during follow up, patients with irregular drug refills, patients who discontinued the use of metformin, patients who received metformin prescription less than four times, or redefining uterine leiomyoma by using 'diagnostic code' plus 'procedure codes' consistently supported a lower risk of uterine leiomyoma in ever users of metformin.

CONCLUSION

Metformin use is associated with a lower risk of uterine leiomyoma.

A comparison between the effects of metformin and megestrol on simple endometrial hyperplasia

INTRODUCTION

Endometrial hyperplasia is one of the most serious causes of severe abnormal bleeding and also can be a precursor of endometrial carcinoma.

OBJECTIVE

The purpose of the present study was to compare the effects of metformin and megestrol on the endometrial hyperplasia.

METHODS

The study was performed as a randomized clinical trial on 42 cases of histopathologically confirmed simple endometrial hyperplasia without atypia. The eligible women were randomly assigned into two groups. In metformin group, metformin was prescribed, 500 mg twice a day (1000 mg daily), for a duration of 4 weeks, and then, followed by 1500 mg daily, for 8 more weeks. In the megestrol group, megestrol was prescribed 40 mg daily for 12 weeks. At the end of the duration of the treatment, endometrial sampling was performed and the results were compared between the two groups.

RESULTS

The women of the two groups did not have significant difference according to age, BMI and gravidity, parity and history of abortion. Overall, 18 women (81.8%) in metformin group and 12 women (60%) in the megestrol group had normal endometrial histology, after 12 weeks of treatment (p = 0.11).

CONCLUSION

Metformin is comparable with megestrol for the treatment of simple endometrial hyperplasia.

A Proteomic Approach for the Identification of Up-Regulated Proteins Involved in the Metabolic Process of the Leiomyoma

Uterine leiomyoma is the most common benign smooth muscle cell tumor of the uterus. Proteomics is a powerful tool for the analysis of complex mixtures of proteins. In our study, we focused on proteins that were upregulated in the leiomyoma compared to the myometrium. Paired samples of eight leiomyomas and adjacent myometrium were obtained and submitted to two-dimensional gel electrophoresis (2-DE) and mass spectrometry for protein identification and to Western blotting for 2-DE data validation. The comparison between the patterns revealed 24 significantly upregulated (p < 0.05) protein spots, 12 of which were found to be associated with the metabolic processes of the leiomyoma and not with the normal myometrium. The overexpression of seven proteins involved in the metabolic processes of the leiomyoma was further validated by Western blotting and 2D Western blotting. Four of these proteins have never been associated with the leiomyoma before. The 2-DE approach coupled with mass spectrometry, which is among the methods of choice for comparative proteomic studies, identified a number of proteins overexpressed in the leiomyoma and involved in several biological processes, including metabolic processes. A better understanding of the mechanism underlying the overexpression of these proteins may be important for therapeutic purposes.

Suppression of phosphatase and tensin homolog protects insulin-resistant cells from apoptosis

In the present study, a glucosamine-induced model of insulin-resistant skeletal muscle cells was established in order to investigate the effect of inhibition of phosphatase and tensin homolog (PTEN)/5'-adenosine monophosphate-activated protein kinase (AMPK) on these cells. The glucosamine-induced insulin-resistant skeletal muscle cells were produced and the rate of glucose uptake was measured using the glucose oxidase-peroxidase method. The expression levels of PTEN and phosphorylated PTEN (p-PTEN) were assessed using western blotting. Glucose transporter 4 (GLUT4) translocation was detected by immunofluorescence. Cell apoptosis was evaluated using flow cytometry. Following insulin stimulation, the rate of glucose uptake was significantly reduced in the cells with glucosamine-induced insulin-resistance in comparison with those in the control group. The expression and translocation of GLUT4 were reduced in the insulin-resistant muscle cells. By contrast, the expression of PTEN and p-PTEN as well as apoptosis were significantly increased. Following treatment with bisperoxopicolinatooxovanadate (BPV) or metformin in the insulin-resistant skeletal muscle cells, there was an increase in the rate of glucose uptake, an increase in GLUT4 expression and its translocation, a reduction in the expression of PTEN and p-PTEN, and a decrease in cell apoptosis compared with untreated insulin-resistant cells. Glucosamine may be used to produce an effective model of insulin-resistant skeletal muscle cells. Cells with glucosamine-induced insulin-resistance exhibited a reduced expression of GLUT4 and dysfunction in GLUT4 translocation, as well as increased activation of PTEN and increased cell apoptosis. Inhibition of PTEN or its upstream regulator, AMPK, protects glucosamine-induced insulin-resistant skeletal muscle cells from apoptosis.

The anti-diabetic drug metformin inhibits vascular endothelial growth factor expression via the mammalian target of rapamycin complex 1/hypoxia-inducible factor-1α signaling pathway in ELT-3 cells

The aim of this study was to elucidate whether metformin can regulate the expression of vascular endothelial growth factor (VEGF) in rat-derived uterine leiomyoma cells (ELT-3 cells). In vitro studies were conducted using ELT-3 cells. Under normoxic conditions, metformin suppressed VEGF protein levels in the supernatant and cells in a dose-dependent manner. In hypoxia-mimicking conditions, VEGF and hypoxia-inducible factor-1α (HIF-1α) proteins were both highly expressed and were suppressed by the metformin treatment. Metformin did not affect HIF-1α mRNA levels, which indicated that its effects occurred at the post-translational level. Metformin inhibited mammalian target of rapamycin complex 1 (mTORC1) activity by phosphorylating the mTORC1 component raptor. This study revealed the anti-angiogenic activity of metformin in ELT-3 cells by suppressing the expression of VEGF via the mTORC1/HIF-1α pathway. These results indicate that metformin may represent an effective alternative in the future treatment of uterine leiomyomas.

The anti-proliferative effect of metformin in triple-negative MDA-MB-231 breast cancer cells is highly dependent on glucose concentration: implications for cancer therapy and prevention

BACKGROUND

Metformin has been shown to have a strong anti-proliferative effect in many breast cancer cell lines, mainly due to the activation of the energy sensing kinase, AMP-activated protein kinase (AMPK). MDA-MB-231 cells are aggressive and invasive breast cancer cells that are known to be resistant to several anti-cancer agents as well as to the anti-proliferative effect of metformin. As metformin is a glucose lowering drug, we hypothesized that normoglycemia will sensitize MDA-MB-231 cells to the anti-proliferative effect of metformin.

METHODS

MDA-MB-231 cells were treated with increasing metformin concentrations in hyperglycemic or normoglycemic conditions. The growth inhibitory effect of metformin was assessed by MTT assay. The expression of several proteins involved in cell proliferation was measured by Western blotting.

RESULTS

In agreement with previous studies, treatment with metformin did not inhibit the growth of MDA-MB-231 cells cultured in hyperglycemic conditions. However, metformin significantly inhibited MDA-MB-231 growth when the cells were cultured in normoglycemic conditions. In addition, we show that metformin-treatment of MDA-MB-231 cells cultured in normoglycemic conditions and not in hyperglycemic conditions caused a striking activation of AMPK, and an AMPK-dependent inhibition of multiple molecular signaling pathways known to control protein synthesis and cell proliferation.

CONCLUSION

Our data show that normoglycemia sensitizes the triple negative MDA-MB-231 breast cancer cells to the anti-proliferative effect of metformin through an AMPK-dependent mechanism.

GENERAL SIGNIFICANCE

These findings suggest that tight normoglycemic control may enhance the anti-proliferative effect of metformin in diabetic cancer patients.

Proceedings from the Third National Institutes of Health International Congress on Advances in Uterine Leiomyoma Research: comprehensive review, conference summary and future recommendations

BACKGROUND Uterine fibroids are the most common gynecologic tumors in women of reproductive age yet the etiology and pathogenesis of these lesions remain poorly understood. Age, African ancestry, nulliparity and obesity have been identified as predisposing factors for uterine fibroids. Symptomatic tumors can cause excessive uterine bleeding, bladder dysfunction and pelvic pain, as well as associated reproductive disorders such as infertility, miscarriage and other adverse pregnancy outcomes. Currently, there are limited noninvasive therapies for fibroids and no early intervention or prevention strategies are readily available. This review summarizes the advances in basic, applied and translational uterine fibroid research, in addition to current and proposed approaches to clinical management as presented at the 'Advances in Uterine Leiomyoma Research: 3rd NIH International Congress'. Congress recommendations and a review of the fibroid literature are also reported. METHODS This review is a report of meeting proceedings, the resulting recommendations and a literature review of the subject. RESULTS The research data presented highlights the complexity of uterine fibroids and the convergence of ethnicity, race, genetics, epigenetics and environmental factors, including lifestyle and possible socioeconomic parameters on disease manifestation. The data presented suggest it is likely that the majority of women with uterine fibroids will have normal pregnancy outcomes; however, additional research is warranted. As an alternative to surgery, an effective long-term medical treatment for uterine fibroids should reduce heavy uterine bleeding and fibroid/uterine volume without excessive side effects. This goal has not been achieved and current treatments reduce symptoms only temporarily; however, a multi-disciplined approach to understanding the molecular origins and pathogenesis of uterine fibroids, as presented in this report, makes our quest for identifying novel targets for noninvasive, possibly nonsystemic and effective long-term treatment very promising. CONCLUSIONS The Congress facilitated the exchange of scientific information among members of the uterine leiomyoma research and health-care communities. While advances in research have deepened our knowledge of the pathobiology of fibroids, their etiology still remains incompletely understood. Further needs exist for determination of risk factors and initiation of preventive measures for fibroids, in addition to continued development of new medical and minimally invasive options for treatment.