Ovulatory response to treatment of polycystic ovary syndrome is associated with a polymorphism in the STK11 gene

Metformin: Past, Present, and Future

PURPOSE OF REVIEW

This review provides the most recent update of metformin, a biguanide oral antihyperglycemic drug used as a first-line treatment in type 2 diabetes mellitus.

RECENT FINDINGS

Metformin continues to dominate in the world of antidiabetics, and its use will continue to rise because of its high efficiency and easy availability. Apart from type 2 diabetes, research is exploring its potential in other conditions such as cancer, memory loss, bone disorders, immunological diseases, and aging. Metformin is the most prescribed oral antidiabetic worldwide. It has been in practical use for the last six decades and continues to be the preferred drug for newly diagnosed type 2 diabetes mellitus. It reduces glucose levels by decreasing hepatic glucose production, reducing intestinal glucose absorption, and increasing insulin sensitivity. It can be used as monotherapy or combined with other antidiabetics like sulfonylureas, DPP-4 inhibitors, SGLT-2 inhibitors, or insulin, improving its efficacy. Metformin can be used once or twice daily, depending on requirements. Prolonged usage of metformin may lead to abdominal discomfort, deficiency of Vitamin B12, or lactic acidosis. It should be used carefully in patients with renal impairment. Recent studies have explored additional benefits of metformin in polycystic ovarian disease, gestational diabetes mellitus, cognitive disorders, and immunological diseases. However, more extensive studies are needed to confirm these additional benefits.

Salt-inducible kinases regulate androgen synthesis in theca cells by enhancing CREB signaling

Ovulation is the pinnacle of folliculogenesis, a process that requires an interplay between the oocyte, the granulosa cells, and the theca cells (TCs). TCs are the only source of ovarian androgens, which play a vital role in female fertility. However, abnormally elevated androgen levels reduce fertility. Therefore, uncovering novel mechanisms regulating androgen synthesis in TCs is of great significance. We have shown that salt-inducible kinases (SIKs) regulate granulosa cell steroidogenesis. Here, we investigated whether SIKs regulate androgen production in TCs. SIK2 and SIK3 were detected in the TCs of mouse ovaries and isolated TCs. Next, TCs in culture were treated with luteinizing hormone (LH) in the presence or absence of a highly specific SIK inhibitor. SIK inhibition enhanced the stimulatory effect of LH on steroidogenic gene expression and androgen production in a concentration-dependent manner. SIK inhibition alone stimulated the expression of steroidogenic genes and increased androgen production. Activation of adenylyl cyclase with forskolin or emulation of increased intracellular cyclic AMP levels stimulated steroidogenesis, an effect that was enhanced by the inhibition of SIK activity. The stimulatory effect of downstream targets of cyclic AMP was also significantly augmented by SIK inhibition, suggesting that SIKs control targets downstream cyclic AMP. Finally, it is shown that SIK2 knockout mice have higher circulating testosterone than controls. This evidence shows that TCs express SIKs and reveal novel roles for SIKs in the regulation of TC function and androgen production. This information could contribute to uncovering therapeutic targets to treat hyperandrogenic diseases.

Relationship Between Genetic Polymorphisms in Cell Cycle Regulatory Gene TP53 and Polycystic Ovarian Syndrome: A Case-Control Study and In Silico Analyses

Polycystic ovarian syndrome (PCOS) is a complex endocrine and metabolic condition with several potential causes. Insulin resistance is a hallmark of PCOS that often coexists with hirsutism, hyperandrogenism, being overweight, and hormonal imbalances. The functioning of multiple replication and transcription factors is regulated by tumor suppressor genes (TSGs), which play a crucial role in maintaining genomic integrity and controlling the cell cycle of granulosa cells. In the present study, we examined how three single nucleotide polymorphisms (SNPs) in TP53, a cell cycle regulatory gene, affect the risk of developing PCOS in a sample of an Iranian population. Genomic DNA was extracted from 200 PCOS patients and 200 healthy women to analyze TP53 rs17880604, rs1625895, and rs1042522 SNPs using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Our findings revealed that the majority of PCOS cases were overweight [25 < body mass index (BMI) < 30]. A positive association was observed between the TP53 rs1042522 SNP and the risk of PCOS under codominant heterozygous and overdominant genetic patterns (odds ratio > 1). Meanwhile, a negative association was observed between TP53 SNPs (rs1625895, rs17880604) and susceptibility to PCOS under codominant heterozygous and dominant models of inheritance (odds ratio < 1). Moreover, different genotype and haplotype combinations of rs17880604/rs1625895/rs1042522 conferred a decreased risk of PCOS in our population. We found no statistical difference in the frequency of TP53 genotypes between PCOS cases and/or controls in terms of BMI, waist circumference, prolactin level, and markers of lipid and carbohydrate profile (P > 0.05). Molecular dynamic prediction showed that the missense substitution in the 17p13.1 position (rs1042522) could change the properties and secondary structure of the p53 protein. As inherited risk factors, TP53 variations may play a  pivotal role in the pathogenesis of PCOS among Iranian women. Replicated population-based studies on other ethnicities are required to find the genetic contribution of variants of TP53, or SNPs located in other TSGs, to the etiology of this endocrine disease.

Updates in diagnosing polycystic ovary syndrome-related infertility

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a condition that affects approximately 13% of reproductive age women and is characterized by androgen excess, menstrual irregularity and altered ovarian morphology. PCOS presents a complex etiology and pathophysiology, which still requires a detailed investigation of biochemical signatures to identify the molecules and mechanisms that govern it.

AREAS COVERED

This narrative review summarizes the main molecular alterations found in the ovarian follicular fluid, endometrium and placenta of women with PCOS, and the genotypes potentially associated with the outcome of infertility treatments in PCOS.

EXPERT OPINION

PCOS is associated with multiple alterations in growth factors, sex steroid hormones, reactive oxygen species, proinflammatory cytokines and adipokines, which contribute to follicle arrest/ anovulation or suboptimal corpus luteum function, and ultimately to menstrual irregularity and hyperandrogenic symptoms. A panel of PCOS biomarkers should include, besides ovarian products, markers of adipose tissue function, insulin resistance, vascular health, and low-grade chronic inflammation. The effects of ovarian stimulation drugs on infertile women with PCOS are likely to be modified by genetic factors, but the available evidence is heterogeneous; therefore, future studies should evaluate standard treatments and pre-specified outcomes of interest to provide more conclusive answers.

Molecular basis of AR and STK11 genes associated pathogenesis via AMPK pathway and adipocytokine signalling pathway in the development of metabolic disorders in PCOS women

Background

One of the most common hormonal disorders in women of reproductive age is polycystic ovary syndrome (PCOS). In recent years, it has been found that insulin resistance is a common metabolic abnormality in women with PCOS and leads to an elevated risk of type 2 diabetes mellitus. To explore the differentially expressed genes (DEGs) that regulate these kinds of metabolic risks in PCOS women, we chose the gene expression profile of GSE8157 from the gene expression omnibus (GEO) database.

Results

Using the GEO2R tool, we identified a total of 339 DEGs between the case and the control sample groups. Gene ontology and Kyoto encyclopedia of gene and genome pathway enrichment analysis were subsequently conducted. High connectivity, betweenness centrality, bottleneck centrality, closeness centrality, and radiality measures were used to rank the ten hub genes. Furthermore, the overlap of these genes resulted in the development of two key genes, AR and STK11. The AMPK and adipocytokine signaling pathways are the two main pathways that these DEGs are involved.

Conclusions

The backbone genes, hub genes and pathways identified would assist us in further exploring the molecular basis of developing risk of type 2 diabetes mellitus in PCOS women and thus provide diagnostic or therapeutic clues.

An update of polycystic ovary syndrome: causes and therapeutics options

Polycystic ovary syndrome (PCOS) is a heterogeneous disorder characterized by menstrual irregularities, chronic anovulation, hirsutism, androgenic alopecia, and acne. At diagnosis, patients can with different manifestations according to the disease phenotype, patient's age, and lifestyle. However, most patients pursue medical care because of the clinical symptoms of PCOS, such as hyperandrogenism, menstrual irregularities and infertility. Recent studies have shown that PCOS is associated with 80% of anovulatory infertility; however, the precise mechanism of PCOS-induced anovulation is still undetermined. The treatment strategies of PCOS are symptomatic depending mainly on the desired goals and clinical benefits. Life style intervention is still the first line treatment option for overweight females seeking pregnancy. In addition, there are many pharmacological agents that could be added to induce ovulation such as metformin, and clomiphene citrate. Nowadays, many patients preferred to use some herbal medicine that was proved to have potential therapeutic benefits in many studies in the management of PCOS. The purpose of this review was to discuss PCOS-induced infertility and the available therapeutic options as well as the impact of COVID-19 infection on the success of fertility attempts. To address this purpose, Pubmed, Scopus, EMBASE and Google databases were searched for studies discussing PCOS-induced infertility. The literature search revealed the proper therapeutic plans to treat PCOS-induced infertility, and that treatment should be modified according to patient's complaints, reproductive desires, and disease phenotypes. In conclusion, the use of specific therapeutic agents and patients' adherence to lifestyle interventions could help patients recover their reproductive and metabolic health.

Metabolic reprogramming and immune regulation in viral diseases

The recent outbreak and transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) worldwide and the ensuing coronavirus disease 2019 (COVID-19) pandemic has left us scrambling for ways to contain the disease and develop vaccines that are safe and effective. Equally important, understanding the impact of the virus on the host system in convalescent patients, healthy otherwise or with co-morbidities, is expected to aid in developing effective strategies in the management of patients afflicted with the disease. Viruses possess the uncanny ability to redirect host metabolism to serve their needs and also limit host immune response to ensure their survival. An ever-increasingly powerful approach uses metabolomics to uncover diverse molecular signatures that influence a wide array of host signalling networks in different viral infections. This would also help integrate experimental findings from individual studies to yield robust evidence. In addition, unravelling the molecular mechanisms harnessed by both viruses and tumours in their host metabolism will help broaden the repertoire of therapeutic tools available to combat viral disease.

Genetics of Polycystic Ovary Syndrome: What is New?

Polycystic ovary syndrome (PCOS) is a complex genetic disorder with many genetic loci contributing small risk. Large genome-wide association studies identified 21 genetic risk loci for PCOS in European and Han Chinese women. The genetic architecture is similar across PCOS diagnostic categories. The next wave of analysis will incorporate large genotyped datasets linked to medical records, increasing numbers and ethnic subsets. The resulting genetic risk loci can then be used to create robust genetic risk scores enhanced with clinical information, environment and lifestyle data for a precision medicine approach to PCOS diagnosis and treatment.

A safety evaluation of current medications for adult women with the polycystic ovarian syndrome not pursuing pregnancy

INTRODUCTION

The polycystic ovary syndrome (PCOS) is a very prevalent disorder in premenopausal women. Cardiovascular risk factors cluster in these patients, raising concern about the safety of the drugs commonly used to ameliorate symptoms of androgen excess in in this population at risk of cardiovascular morbidity.

AREAS COVERED

This review summarizes the clinical efficacy and safety profiles of drugs commonly used for the management of hyperandrogenic symptoms and endometrial protection in adult women with PCOS who do not seek pregnancy.

EXPERT OPINION

Antiandrogenic drugs usually used in adult women with PCOS carry a low risk of severe side effects. In spite of the cardiovascular risk profile of women with PCOS, and that individualized risk assessment is of paramount importance, there is no solid evidence supporting that the use of combined oral contraceptives in these women increases the risk of cardiovascular or thromboembolic events compared with the general population. However, virtually all these drugs are used in an off-label fashion. Large, high-quality studies addressing the long-term safety of pharmacological treatments in women with PCOS are definitely needed.

Oncology and Pharmacogenomics Insights in Polycystic Ovary Syndrome: An Integrative Analysis

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries. Epidemiological findings revealed that women with PCOS are prone to develop certain cancer types due to their shared metabolic and endocrine abnormalities. However, the mechanism that relates PCOS and oncogenesis has not been addressed. Herein, in this review article the genomic status, transcriptional and protein profiles of 264 strongly PCOS related genes (PRG) were evaluated in endometrial cancer (EC), ovarian cancer (OV) and breast cancer (BC) exploring oncogenic databases. The genomic alterations of PRG were significantly higher when compared with a set of non-diseases genes in all cancer types. PTEN had the highest number of mutations in EC, TP53, in OC, and FSHR, in BC. Based on clinical data, women older than 50 years and Black or African American females carried the highest ratio of genomic alterations among all cancer types. The most altered signaling pathways were p53 in EC and OC, while Fc epsilon RI in BC. After evaluating PRG in normal and cancer tissue, downregulation of the differentially expressed genes was a common feature. Less than 30 proteins were up and downregulated in all cancer contexts. We identified 36 highly altered genes, among them 10 were shared between the three cancer types analyzed, which are involved in the cell proliferation regulation, response to hormone and to endogenous stimulus. Despite limited PCOS pharmacogenomics studies, 10 SNPs are reported to be associated with drug response. All were missense mutations, except for rs8111699, an intronic variant characterized as a regulatory element and presumably binding site for transcription factors. In conclusion, in silico analysis revealed key genes that might participate in PCOS and oncogenesis, which could aid in early cancer diagnosis. Pharmacogenomics efforts have implicated SNPs in drug response, yet still remain to be found.

Polycystic ovarian syndrome in adolescents: From diagnostic criteria to therapeutic management

Polycystic ovarian syndrome is a common endocrinologic condition diagnosed in women of childbearing age. It is primarily associated with androgen excess and ovarian dysfunction, which contribute to menstrual irregularity, oligo-anovulation, infertility, hirsutism and acne. It is associated with several systemic conditions, including type 2 diabetes mellitus, cardiovascular disease, obesity and neuropsychological disorders. The exact pathophysiology and clinical features are highly variable and, thus, there is still controversy in defining the diagnostic criteria. In this review, we outline the main diagnostic criteria, discuss the mechanisms involved in the complex pathogenesis, and present the associated clinical manifestations and therapeutic management of the syndrome in adolescents.

Several critical genes and microRNAs associated with the development of polycystic ovary syndrome

BACKGROUND

We aimed to identify key genes and microRNAs (miRNAs) associated with the development of polycystic ovary syndrome (PCOS).

METHODS

GSE84376 mRNA microarray data (15 PCOS granulosa cells and 13 control granulosa cells) and GSE34526 mRNA microarray data (7 PCOS granulosa cells and 3 control granulosa cells) were downloaded from the Gene Expression Omnibus (GEO) database. First, differentially expressed gene (DEG) analysis, gene set enrichment analysis (GSEA) for differentially expressed mRNAs, and protein-protein interaction (PPI) network analysis were conducted. Next, miRNA-target genes were analyzed and functions predicted, and a competing endogenous RNA (ceRNA) network was constructed. Finally, the relationship between miR-486-5p and PRELID2 was experimentally validated.

RESULTS

Spleen tyrosine kinase (SYK), major histocompatibility complex, class II, DR alpha (HLA-DRA), and interleukin 10 (IL-10) were important nodes in the PPI network. Interestingly, HLA-DRA was significantly enriched in phagosomes mediated by Staphylococcus aureus infection, and in IL-10 enriched during S. aureus infection. One miRNA (miR-486-5p) and a single target gene (PRELID2) were obtained from the ceRNA network. Further experiments showed that miR-486-5p is upregulated and PRELID2 is downregulated in PCOS patient granulosa cells, and that miR-486-5p targets the PRELID2 3'UTR. Topological property analysis showed that hsa-miR-4687-5p downregulation and hsa-miR-4651 upregulation determined the levels of most mRNAs. Levels of the hsa-miR-4651 target gene were significantly enriched in the leukocyte transendothelial migration pathway.

CONCLUSIONS

Our results suggest that HLA-DRA and IL-10 may contribute to PCOS progression via phagosome enriched by S. aureus infection, while miR-486-5p may be implicated in follicular development in PCOS by targeting PRELID2. Besides, miR-4651 may be involved in inflammation via leukocyte transendothelial migration, by regulating its target gene. These findings may indicate new directions and constitute a breakthrough in studying the pathophysiology of PCOS.

Single nucleotide polymorphisms in treatment of polycystic ovary syndrome: a systematic review

As 15-20% of reproductive aged females are suffering from polycystic ovary syndrome (PCOS), a large number of pharmacological preparations are frequently available in the market for the treatment of PCOS; however, they seem to be ineffective and cause undesirable side effects. This has emphasized the need to optimize dosage regimens for individualized treatment. The objective of this systematic review is to review single nucleotide polymorphisms (SNPs) associated with drugs used for the treatment of PCOS to understand pharmacogenetics variability of patients to drug response there by helping clinicians in designing tailored treatments and possibly reducing adverse drug reactions. A comprehensive electronic literature search was conducted to highlight some clinically relevant SNPs that act to influence PCOS and associated co-morbidities. A total of 16 studies were included in this review. These genetic variations can be used as a potential target for pharmacotherapy and pharmacogenetic clinical trials for better diagnosis, management, and treatment planning.

Polycystic Ovary Syndrome: Implication for Drug Metabolism on Assisted Reproductive Techniques-A Literature Review

Polycystic ovary syndrome (PCOS) affects 6-10% of women and could be considered one of the most common endocrine alterations in women of reproductive age. The syndrome is characterized by several hormonal and metabolic alterations, including insulin resistance and hyperandrogenism, which play a severe detrimental role in the patient's fertility. We aimed to offer an overview about drug metabolism in the PCOS population. Nevertheless, we did not find any study that directly compared drug metabolism between PCOS and healthy women. We therefore decided to summarize briefly how hormonal and insulin sensitizer drugs act differently in healthy and PCOS women, who show altered steroidogenesis by theca cells and metabolic imbalance, focusing especially on assisted reproductive techniques. To date, data about drug metabolism in the PCOS population appears to be extremely limited. This important gap could have significant implications for therapeutic approaches and future perspectives: the dosage of drugs commonly used for the treatment of PCOS women should be tailored according to each patient's characteristics; we should implement new clinical trials in order to identify the best pharmacologic strategy for PCOS patients undergoing in vitro fertilization (IVF); it would be advisable to create an international expert panel to investigate the drug metabolism in the PCOS population.

Differentially expressed novel alternatively spliced transcript variant of tumor suppressor Stk11 gene in mouse

Serine/threonine kinase 11 (STK11) is a protein kinase that is encoded by Stk11 gene located on chromosome 19 and 10 in humans and mouse respectively. It acts as a master kinase of adenine monophosphate-activated protein kinase (AMPK) pathway that coordinates the regulation of cellular energy metabolism and cell division. STK11 exerts effect by activating more than 14 kinases including AMPK and AMPK-related kinases. It is also known to regulate cell polarity and acts as tumor suppressor. Alternative splicing of pre-mRNA is a mechanism which results in multiple transcript variants of a single gene. In human, two STK11 isoforms have been reported, an alternatively spliced isoform which has variation at its C-terminal and mostly expressed in testis (LKB1_S). Another isoform exhibiting oncogenic properties lacks few residues at its N-terminal (ΔN-LKB1). In the present study, we report the identification of a new transcript variant Stk11N which is generated through alternative splicing. The new variant was found to have differential and tissue specific expression at Postnatal-7 and adult stages of mouse. As compared to the known variant Stk11C, the conceptually translated amino acid sequences of the new variant differ from exon-E2 onwards. In silico post translational studies of the new and published variant show similarity in some of the properties while differ in properties like nuclear export signals, phosphorylation, glycosylation, etc. Thus, alternative splicing of Stk11 gene generating new variant with heterogeneous properties suggests for complex regulation of these variants in controlling the AMPK pathway and other functions.

Metformin therapy for the reproductive and metabolic consequences of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS), the most common hormonal disorder among women of reproductive age, has various metabolic and reproductive consequences. Metformin was originally shown to lower testosterone levels in women with PCOS in the 1990s, an effect presumably related to its insulin sensitising actions. However, the precise mechanisms of metformin action in PCOS remain unclear and there is considerable heterogeneity in the clinical response to this therapy in women with PCOS. Recent evidence indicates that genetic factors may play a significant role in predicting response to metformin therapy in PCOS and future studies are needed to further identify women who are most likely to benefit from this therapy. At present, there is no clear evidence to support broad metformin use in PCOS. Well-designed prospective trials are needed to establish clear benefit for metformin use in the treatment of the reproductive and metabolic consequences associated with PCOS.

Precision reproductive medicine: multigene panel testing for infertility risk assessment

The concept of precision medicine relies on a thorough understanding of the consequences of unique features of individual patients, such as environmental exposures and genetic profiles. A key component of implementing individualized care in this paradigm will be improved assessment of genetic risk. Compared with single gene tests, multigene panel testing-which has recently become commercially available for female infertility-offers the possibility of a more comprehensive and efficient risk evaluation. However, as the use of multigene panel testing for breast cancer risk has shown, this approach must be used judiciously to ensure its usefulness in a clinical setting. Key challenges which have been encountered in oncology include the interpretation of gene variants of questionable clinical effect and a lack of evidence to guide management after variants are identified. In this review, the core concepts of multigene panel testing for risk assessment are discussed, with careful attention to both its shortcomings as well as its potential for benefit in reproductive medicine.

STK11 rs2075604 Polymorphism Is Associated with Metformin Efficacy in Chinese Type 2 Diabetes Mellitus

Metformin is a classical oral antidiabetic drug, often recommended to be the first-choice treatment of type 2 diabetes mellitus (T2DM). Based on the previous research on STK11 and diabetes, we aimed to investigate the distributive characteristic of STK11 rs2075604 polymorphism and the potential influence of STK11 rs2075604 polymorphism on metformin efficacy among Chinese T2DM patients. There was no significant difference between T2DM patients (G = 64.8%, T = 35.2%) and healthy subjects (G = 62.7%, T = 37.2%) in STK11 rs2075604 genotype and allele frequencies. After 12 weeks of treatment, 62 patients were defined as the responders and 32 patients as nonresponders according to the decrease of HbA1c level. And the GT + TT genotype in STK11 rs2075604 can decrease HbA1c level more significantly than the GG genotype. Furthermore, the allele frequency of T in the STK11 rs2075604 was higher in the responders than the nonresponders (43.55% versus 26.56%). The T allele in the STK11 rs2075604 had a 2.133 times great chance of responding to metformin treatment. In conclusion, this study suggested that the STK11 rs2075604 genetic polymorphism was significantly associated with metformin efficacy in Chinese T2DM patients and the carriers of the T allele may gain a better therapeutic metformin efficacy compared with the G allele. This trial is registered with clinical study registration number NCT03155087.

The Pathogenesis of Polycystic Ovary Syndrome (PCOS): The Hypothesis of PCOS as Functional Ovarian Hyperandrogenism Revisited

Polycystic ovary syndrome (PCOS) was hypothesized to result from functional ovarian hyperandrogenism (FOH) due to dysregulation of androgen secretion in 1989-1995. Subsequent studies have supported and amplified this hypothesis. When defined as otherwise unexplained hyperandrogenic oligoanovulation, two-thirds of PCOS cases have functionally typical FOH, characterized by 17-hydroxyprogesterone hyperresponsiveness to gonadotropin stimulation. Two-thirds of the remaining PCOS have FOH detectable by testosterone elevation after suppression of adrenal androgen production. About 3% of PCOS have a related isolated functional adrenal hyperandrogenism. The remaining PCOS cases are mild and lack evidence of steroid secretory abnormalities; most of these are obese, which we postulate to account for their atypical PCOS. Approximately half of normal women with polycystic ovarian morphology (PCOM) have subclinical FOH-related steroidogenic defects. Theca cells from polycystic ovaries of classic PCOS patients in long-term culture have an intrinsic steroidogenic dysregulation that can account for the steroidogenic abnormalities typical of FOH. These cells overexpress most steroidogenic enzymes, particularly cytochrome P450c17. Overexpression of a protein identified by genome-wide association screening, differentially expressed in normal and neoplastic development 1A.V2, in normal theca cells has reproduced this PCOS phenotype in vitro. A metabolic syndrome of obesity-related and/or intrinsic insulin resistance occurs in about half of PCOS patients, and the compensatory hyperinsulinism has tissue-selective effects, which include aggravation of hyperandrogenism. PCOS seems to arise as a complex trait that results from the interaction of diverse genetic and environmental factors. Heritable factors include PCOM, hyperandrogenemia, insulin resistance, and insulin secretory defects. Environmental factors include prenatal androgen exposure and poor fetal growth, whereas acquired obesity is a major postnatal factor. The variety of pathways involved and lack of a common thread attests to the multifactorial nature and heterogeneity of the syndrome. Further research into the fundamental basis of the disorder will be necessary to optimally correct androgen levels, ovulation, and metabolic homeostasis.

Scientific Statement on the Diagnostic Criteria, Epidemiology, Pathophysiology, and Molecular Genetics of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a heterogeneous and complex disorder that has both adverse reproductive and metabolic implications for affected women. However, there is generally poor understanding of its etiology. Varying expert-based diagnostic criteria utilize some combination of oligo-ovulation, hyperandrogenism, and the presence of polycystic ovaries. Criteria that require hyperandrogenism tend to identify a more severe reproductive and metabolic phenotype. The phenotype can vary by race and ethnicity, is difficult to define in the perimenarchal and perimenopausal period, and is exacerbated by obesity. The pathophysiology involves abnormal gonadotropin secretion from a reduced hypothalamic feedback response to circulating sex steroids, altered ovarian morphology and functional changes, and disordered insulin action in a variety of target tissues. PCOS clusters in families and both female and male relatives can show stigmata of the syndrome, including metabolic abnormalities. Genome-wide association studies have identified a number of candidate regions, although their role in contributing to PCOS is still largely unknown.

Polycystic ovary syndrome (PCOS) with melanocytic mucosal macules: the role of STK11 gene polymorphisms in PCOS and Peutz-Jeghers syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a complex genetic disorder that is the most common endocrinopathy that affects women.

OBSERVATIONS

We report two individuals with PCOS with a genetic polymorphism in serine threonine kinase 11 (STK11). Both these individuals developed mucosal pigmentation suggesting Peutz-Jeghers syndrome (PJS), which is associated with mutations in STK11. Both individuals showed some improvement in their metabolic and endocrine dysregulation with therapies commonly used for PCOS. However, they continued to show progression of mucosa pigmentation.

CONCLUSIONS

This is the first report of clinical overlap in individuals with PCOS and PJS, even though some individuals with PCOS show a polymorphism in STK11, which is the gene mutated in PJS. The importance of this clinical association is not clear but may be significant because of the association of STK11 dysregulation and the development of internal tumors.

An update on the pharmacogenomics of metformin: progress, problems and potential

The increasing prevalence of Type 2 diabetes has emphasized the need to optimize treatment regimens. Metformin, the most widely used oral agent, is recommended as first-line drug therapy by multiple professional organizations. Response to metformin varies significantly at the individual level; this heterogeneity may be explained in part by genetic factors. Understanding these underlying factors may aid with tailoring treatment for individual patients as well as with designing improved Type 2 diabetes therapies. The past 10 years have seen substantial progress in the understanding of the pharmacogenetics of metformin response. The majority of this work has focused on genes involved in the pharmacokinetics of metformin. Owing to the uncertainty surrounding its mechanism of action, studies of pharmacodynamic genetics have been relatively few; genome-wide approaches have the potential to illuminate the molecular details of metformin response. In this review we summarize current knowledge about metformin pharmacogenetics and suggest directions for future investigation.

Potential and real 'antineoplastic' and metabolic effect of metformin in diabetic and nondiabetic postmenopausal females

AIM

The goal of this study was to determine if the single nucleotide polymorphisms marking potential sensitivity to metformin (MF) correlate with hormone-metabolic status as well as with actual response to MF in postmenopausal cancer patients with or without Type 2 diabetes mellitus and in diabetics without cancer.

PATIENTS & METHODS

The carriage of ten different SNPs was evaluated in all patients by PCR, and hormone-metabolic status was estimated by anthropometry, ELISA and enzyme colorimetric assays. The response to daily 1-1.7 g of MF was studied based on hormone-metabolic parameters and indirect end points (endometrium thickness, mammographic breast density).

RESULTS & CONCLUSION

The changes in evaluated 'antineoplastic' and metabolic response marker values were seen in 33.3 and 61.8% of the cases, respectively. Several genetic markers were found that showed an inclination to less frequent 'antineoplastic' or more frequent metabolic response to MF which may be helpful in further studies of this drug in cancer patients.

Metformin in women with PCOS, pros

Metformin is an old insulin sensitizer that has been widely used in women with polycystic ovary syndrome (PCOS) to treat metabolic comorbidities and may also improve ovarian dysfunction in women with PCOS. In fact, metformin may improve insulin resistance, a common finding of PCOS, and reduce insulin blood levels. In this way, androgen production rates can be reduced, and in a subset of women, menses abnormalities and ovulatory rates may improve. The current Endocrine Society Guidelines recommend the use of metformin during adolescence, particularly when excess body weight is present. In the presence of obesity and glucose intolerance states, particularly if those patients fail to modify their lifestyles, metformin may have some significant benefits. Finally, although this drug should not be used as a first-line treatment for ovulatory dysfunctions in adult women with PCOS, there are data supporting the suggestion that in many cases pretreatment with metformin may favor ovulatory response to clomiphene citrate. This article summarizes the available evidence in the favor of metformin use in women with PCOS and emphasizes the need for an individualized therapeutic approach.

Adenosine monophosphate-activated kinase and its key role in catabolism: structure, regulation, biological activity, and pharmacological activation

Adenosine monophosphate-activated protein kinase (AMPK) is a cellular energy sensor, which once activated, plays a role in several processes within the cell to restore energy homeostasis. The protein enhances catabolic pathways, such as β-oxidation and autophagy, to generate ATP, and inhibits anabolic processes that require energy, including fatty acid, cholesterol, and protein synthesis. Due to its key role in the regulation of critical cellular pathways, deregulation of AMPK is associated with the pathology of many diseases, including cancer, Wolff-Parkinson-White syndrome, neurodegenerative disorders, diabetes, and metabolic syndrome. In fact, AMPK is a target of some pharmacological agents implemented in the treatment of diabetes (metformin and thiazolidinediones) as well as other naturally derived products, such as berberine, which is used in traditional medicine. Due to its critical role in the cell and the pathology of several disorders, research into developing AMPK as a therapeutic target is becoming a burgeoning and exciting field of pharmacological research. A profound understanding of the regulation and activity of AMPK would enhance its development as a promising therapeutic target.

Convergence of IPMK and LKB1-AMPK signaling pathways on metformin action

Metformin is a biguanide drug that is widely prescribed for type 2 diabetes. Metformin suppresses hepatic gluconeogenesis and increases fatty acid oxidation. Although studies have suggested that metformin acts, at least in part, via activation of the liver kinase B1 (LKB1)/AMP-activated protein kinase (AMPK) pathway, the specific molecular mechanisms underlying metformin's regulation of glucose and lipid metabolism have not been well delineated. Recently, we have shown that inositol polyphosphate multikinase (IPMK) plays an important role in cellular energy metabolism and glucose-mediated AMPK regulation. Here we investigated the role of IPMK in metformin-induced AMPK activation. We observed that metformin-mediated activation of AMPK was impaired in the absence of IPMK. Overexpression of wild-type IPMK was sufficient to restore LKB1-AMPK activation by either metformin or AICAR in IPMK(-/-) murine embryonic fibroblast cells, suggesting that IPMK may act as an upstream regulator of LKB1-AMPK signaling in response to metformin. Moreover, this regulation was mediated by protein-protein interaction between IPMK and LKB1 as a dominant-negative peptide, which abrogates this interaction, attenuated metformin's ability to activate AMPK. Our data demonstrate that IPMK plays an important role in LKB1/AMPK signaling and may be targeted for treatment of metabolic diseases.

Direct effects of metformin in the endometrium: a hypothetical mechanism for the treatment of women with PCOS and endometrial carcinoma

Although a number of in vitro studies have demonstrated the antiproliferative, anti-invasive, and antimetastatic effects of metformin in multiple cancer cell types, its cellular and molecular mechanisms of anti-cancer action in the endometrium of women with polycystic ovary syndrome (PCOS) have not yet been fully elucidated. Organic cation transporters (OCTs) and multidrug and toxin extrusion proteins (MATEs) are known to be involved in metformin uptake and excretion in cells. In this article, we discuss the novel therapeutic possibilities for early-stage endometrial carcinoma (EC) in women with PCOS focusing on metformin, which might have a direct effect in the endometrium through the OCTs and MATEs. We then review the molecular mechanism(s) of the action of metformin in the endometrium and highlight possible mechanistic insights into the inhibition of cell proliferation and tumor growth and, ultimately, the reversal of early-stage EC into normal endometria in women with PCOS.

Metformin resistance alleles in polycystic ovary syndrome: pattern and association with glucose metabolism

Insulin-sensitizer treatment with metformin is common in polycystic ovary syndrome (PCOS). OCT alleles were investigated in PCOS patients to identify genetic ‘bad responders’ and ‘nonresponders’ to metformin including their possible effects on glucose metabolism without treatment. We genotyped eight SNPs in OCT1, OCT2 and ATM genes in 676 women with PCOS and 90 control women, we also measured oral glucose tolerance tests prior to treatment. Nonfunctional alleles were present in 29.8% and low-functional alleles in 57.9% of our PCOS cohort. OCT variants were significantly associated with elevated baseline and glucose-induced C-peptide levels in PCOS. Metformin bad responders or nonresponders based on OCT genotypes might be relevant in clinical practice – their modulation of metformin pharmacokinetics and pharmacodynamics and metformin-independent glucose effects remain to be elucidated.

Original submitted 7 June 2013; Revision submitted 28 October 2013

Metformin: On Ongoing Journey across Diabetes, Cancer Therapy and Prevention

Cancer metabolism is the focus of intense research, which witnesses its key role in human tumors. Diabetic patients treated with metformin exhibit a reduced incidence of cancer and cancer-related mortality. This highlights the possibility that the tackling of metabolic alterations might also hold promising value for treating cancer patients. Here, we review the emerging role of metformin as a paradigmatic example of an old drug used worldwide to treat patients with type II diabetes which to date is gaining strong in vitro and in vivo anticancer activities to be included in clinical trials. Metformin is also becoming the focus of intense basic and clinical research on chemoprevention, thus suggesting that metabolic alteration is an early lesion along cancer transformation. Metabolic reprogramming might be a very efficient prevention strategy with a profound impact on public health worldwide.

Genetic polymorphisms potentially associated with response to metformin in postmenopausal diabetics suffering and not suffering with cancer

Metformin is a well-known antidiabetic medication, which, besides diabetes, may be involved into modulation of other age-related pathologies, including cancer. The study concerns 12 gene polymorphisms divided into 2 groups consisting of 6 genes each. The first group was composed from so-called "standard" (S) polymorphisms, for which the connection with metabolic response to metformin is already established. The second group included polymorphisms of genes encoding proteins possibly connected with diabetes mellitus type 2 (DM2), impaired glucose tolerance or cancer and entitled here as "associated" (A). A total of 156 postmenopausal women (average age 60.7 ± 0.7) were included, 37 of them healthy, 64 with type DM2 and concurrent treatment-naïve cancer (mostly breast, endometrial or colorectal cancer), 32 with DM2 without cancer, and 23 with treatment-naïve cancer and normal glucose tolerance. The leading metformin response S-marker in combined group of DM2 patients was the CC variant of OCT1-R61C polymorphism of organic cation transporter protein 1 gene. In cancer patients without DM2, this position belonged to AC and AA genotypes of OCT1_rs622342 polymorphism. Among the A-polymorphisms, GA variant of sex hormone-binding globulin gene SHBG_D356N was less frequently observed in DM2 patients with or without cancer. Besides, in diabetics, the same polymorphic variant of SHBG as well as GC genotype of oxidized lipoprotein receptor OLR1_G501C and GG genotype of locus rs11065987 near BRAP gene were carried rather often in combination with "metformin-positive" variant of OCT1_R61C. In addition, carriers of OCT1_R61C and OCT1_rs622342 polymorphisms with potentially positive reaction to metformin had higher insulin resistance score (HOMA-IR) values. Received data lead to the conclusion that postmenopausal diabetics, both with and without cancer, differ in genetic stigmata of potential response to metformin less than they differ from cancer patients without DM2. As genetic polymorphisms associated with metabolic and anticancer metformin (and, possibly, phenformin) effects may be different, this subject requires further investigation.

Effects of insulin-sensitizing agents and insulin resistance in women with polycystic ovary syndrome

OBJECTIVE

The aim of this study was to investigate the effect of insulin sensitizing agents on hormonal and metabolic parameters as well as menstrual patterns in women with polycystic ovary syndrome (PCOS).

METHODS

One hundred and twenty-three patients with PCOS were included. Metformin was administered to patients at 1,500 mg or 1,700 mg daily for 3 months. If the patients had no improvement of the menstrual cycle or metformin-related adverse effects developed, the patients changed medication to a daily dose of either 15 mg pioglitazone or up to 45 mg. Then resumption of a regular menstrual cycle or recovery of ovulation was evaluated. Hormonal and metabolic profiles were compared between the response and non-response group to insulin sensitizing agents.

RESULTS

One hundred and five patients with PCOS were treated with metformin for 3 months. Forty-eight patients (45.7%) showed improvement of menstrual cycle regularity after 3 months of metformin use, whereas 57 patients (54.3%) had no change. The mean free testosterone measured after 3 months of treatment was significantly lower in metformin responders than in non-responders. The other parameters did not differ between the groups. Of the 23 patients who used pioglitazone for 3 to 6 months, 19 patients (82.6%) showed improvement in their menstrual cycles.

CONCLUSION

Metformin treatment seems to be effective for the improvement of menstrual cyclicity irrespective of insulin resistance in women with PCOS. When metformin related adverse effect occurred, pioglitazone would be effective for aiding the resumption of the menstrual cycle.

A common gene variant in STK11 is associated with metabolic risk markers and diabetes during gestation

OBJECTIVE

To assess whether the common rs8111699 (C528G) variant in STK11 is related to metabolic risk markers in pregnant women and to gestational diabetes mellitus (GDM).

DESIGN

Cross-sectional study.

SETTING

Hospital.

PATIENT(S)

A total of 561 pregnant women: 318 without and 243 with GDM (National Diabetes Data Group criteria).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURES(S)

rs8111699 variant in STK11 (Taqman technology). Fasting glucose, insulin (homeostatic model assessment of insulin resistance and β-cell function [HOMA-IR and -β]) and C-peptide assessed at 24-28 weeks' gestation.

RESULT(S)

In non-GDM women, the G allele in rs8111699 was associated with lower HOMA-IR (CC: 1.3 ± 0.1 mIU/L; GG: 0.9 ± 0.1 mIU/L) and HOMA-β (CC: 165 ± 20 mIU/L; GG: 118 ± 10 mIU/L). In GDM women, the G allele was related to lower body mass index (BMI; CC: 27.9 ± 1.0 kg/m(2); GG: 24.5 ± 0.6 kg/m(2)) and C-peptide (CC: 2.3 ± 0.1 ng/mL; GG: 1.6 ± 0.1 ng/mL). The GG genotype was less frequently observed in GDM women (18% vs. 26%), particularly in heavier GDM women (BMI > median: 14% vs. 28%).

CONCLUSION(S)

In pregnant women, the G allele for the rs8111699 variant in STK11 is associated with a more favorable metabolic phenotype and may protect against the development of GDM, particularly in heavier women.

Targeting LKB1 signaling in cancer

The serine/threonine kinase LKB1 is a master kinase involved in cellular responses such as energy metabolism, cell polarity and cell growth. LKB1 regulates these crucial cellular responses mainly via AMPK/mTOR signaling. Germ-line mutations in LKB1 are associated with the predisposition of the Peutz-Jeghers syndrome in which patients develop gastrointestinal hamartomas and have an enormously increased risk for developing gastrointestinal, breast and gynecological cancers. In addition, somatic inactivation of LKB1 has been associated with sporadic cancers such as lung cancer. The exact mechanisms of LKB1-mediated tumor suppression remain so far unidentified; however, the inability to activate AMPK and the resulting mTOR hyperactivation has been detected in PJS-associated lesions. Therefore, targeting LKB1 in cancer is now mainly focusing on the activation of AMPK and inactivation of mTOR. Preclinical in vitro and in vivo studies show encouraging results regarding these approaches, which have even progressed to the initiation of a few clinical trials. In this review, we describe the functions, regulation and downstream signaling of LKB1, and its role in hereditary and sporadic cancers. In addition, we provide an overview of several AMPK activators, mTOR inhibitors and additional mechanisms to target LKB1 signaling, and describe the effect of these compounds on cancer cells. Overall, we will explain the current strategies attempting to find a way of treating LKB1-associated cancer.

Metformin and cancer: from the old medicine cabinet to pharmacological pitfalls and prospects

Metformin is a biguanide derivative used in the treatment of type II diabetes (T2D) and one of the world's most widely prescribed drugs. Owing to its safety profile, it has been recently promoted for a range of other indications, particularly for its role in cancer prevention. There is evidence from studies in diabetic cohorts, as well as laboratory studies, that the action of metformin depends on a balance between the concentration and duration of exposure, which depends crucially on cell- and tissue-specific pharmacological factors. Mechanistic studies have revealed the involvement of increasingly complex pathways. Yet, there are several missing links regarding the role of drug transporters and drug-drug interactions, as well as the expression levels of transporters in normal versus tumor tissues, which may affect patient exposure and dosing when metformin is used in cancer prevention. This review highlights the current knowledge on metformin action and pharmacology, including novel insights into genomic factors, with a specific focus on cancer prevention. Furthermore, future challenges that may influence therapeutic outcome will be discussed.

Is there a dose-response relationship of metformin treatment in patients with polycystic ovary syndrome? Results from a multicentric study

STUDY QUESTION

Do different dosages of metformin account for different clinical and biochemical outcomes in women with polycystic ovary syndrome (PCOS) and do basal anthropometric and metabolic characteristics of the patients provide any indications regarding the dose required to reach the target effect?

SUMMARY ANSWER

Different doses of metformin exerted the same effects on clinical, biochemical and metabolic parameters in patients affected by PCOS.

WHAT IS KNOWN AND WHAT THIS PAPER ADDS

Since the insulin-sensitizing agents came into use in the management of PCOS, metformin has shown a positive benefits-risks ratio. Nonetheless, therapeutic schedules are not well standardized. This is the first study which systematically analyses the effect of different doses of metformin on clinical, hormonal and metabolic features of PCOS. On the basis of our results, higher doses are no more effective than lower doses.

DESIGN

A multicentric cohort prospective study. A total of 250 PCOS women were enrolled, 49 lost to follow-up. Menstrual cyclicity, hormonal assays, oral glucose tolerance test, lipid profile and ultrasonographic pelvic examination were evaluated at the baseline and after 6 months of metformin treatment at different doses (1000, 1500 and 1700 mg).

PARTICIPANTS AND SETTING

A total of 201 PCOS patients completed the study without protocol violations in three university hospitals: seventy-three patients from Centre A (treated with metformin 500 mg twice a day), 60 patients from Centre B (treated with metformin 500 mg three times a day) and 68 patients from Centre C (treated with metformin 850 mg twice a day).

MAIN RESULTS AND THE ROLE OF CHANCE

Metformin exerted an overall positive effect on the clinical and endocrine-metabolic features of PCOS. The degree of these effects was independent of the administered dosage in every range of basal body mass index (BMI). When patients were stratified according to their insulinaemic status, scattered inter-doses differences were found in some of the outcome measures. Patients who exhibited an increase of >2 menstrual cycles/year were considered as responders to treatment. Responders had a higher basal BMI than non-responders and showed a greater reduction in plasma testosterone levels after metformin treatment, but other outcome measures did not differ significantly. Total insulin secretion in the 180 min following the glucose tolerance test before metformin treatment (basal AUC-I) was significantly correlated with the decrease in insulin secretion induced by metformin in both the whole group and in responders, but only correlated with the variation in the number of cycles in responders.

BIAS, CONFOUNDING AND OTHER REASONS FOR CAUTION

The different doses were administered in different centres, and between-centre variation is a potential confounding factor.

GENERALIZABILITY TO OTHER POPULATIONS

The paradigm of using the minimum effective dose of metformin could be pursued in other pathological conditions characterized by insulin resistance.

STUDY FUNDING/COMPETING INTEREST(S)

No funding or competing interests to declare.

Metformin: multi-faceted protection against cancer

The biguanide metformin, a widely used drug for the treatment of type 2 diabetes, may exert cancer chemopreventive effects by suppressing the transformative and hyperproliferative processes that initiate carcinogenesis. Metformin's molecular targets in cancer cells (e.g., mTOR, HER2) are similar to those currently being used for directed cancer therapy. However, metformin is nontoxic and might be extremely useful for enhancing treatment efficacy of mechanism-based and biologically targeted drugs. Here, we first revisit the epidemiological, preclinical, and clinical evidence from the last 5 years showing that metformin is a promising candidate for oncology therapeutics. Second, the anticancer effects of metformin by both direct (insulin-independent) and indirect (insulin-dependent) mechanisms are discussed in terms of metformin-targeted processes and the ontogenesis of cancer stem cells (CSC), including Epithelial-to-Mesenchymal Transition (EMT) and microRNAs-regulated dedifferentiation of CSCs. Finally, we present preliminary evidence that metformin may regulate cellular senescence, an innate safeguard against cellular immortalization. There are two main lines of evidence that suggest that metformin's primary target is the immortalizing step during tumorigenesis. First, metformin activates intracellular DNA damage response checkpoints. Second, metformin attenuates the anti-senescence effects of the ATP-generating glycolytic metabotype-the Warburg effect-, which is required for self-renewal and proliferation of CSCs. If metformin therapy presents an intrinsic barrier against tumorigenesis by lowering the threshold for stress-induced senescence, metformin therapeutic strategies may be pivotal for therapeutic intervention for cancer. Current and future clinical trials will elucidate whether metformin has the potential to be used in preventive and treatment settings as an adjuvant to current cancer therapeutics.

PI3K-Akt-mTOR and MAPK signaling pathways in polycystic ovarian syndrome, uterine leiomyomas and endometriosis: an update

PI3K-Akt-mTOR and MAP kinase are two important cell signaling pathways that are activated by steroid hormones and growth factors leading to cellular events including gene expression, cell proliferation and survival. These pathways are considered as an attractive target for the development of novel anticancer molecules, and selective inhibitors specifically targeting different components of these cascades have been developed. This review summarizes the current available knowledge on the PI3K-Akt-mTOR and MAPK pathways and their targeting in estrogen-dependent benign gynecological disorders viz. polycystic ovarian syndrome, uterine leiomyomas and endometriosis, which are a significant cause of high morbidity in women of reproductive age group. Increasing knowledge about the role of the two growth regulatory pathways in the pathogenesis of these disorders may give the opportunity to use specific signal transduction inhibitors for management of these patients in future.

Disposition of metformin: variability due to polymorphisms of organic cation transporters

Considerable interindividual variability in clinical efficacy is recognized in the treatment of type 2 diabetes mellitus with the biguanide metformin. Metformin is a substrate of organic cation transporters, which play important roles in gastrointestinal absorption, renal and biliary elimination, and distribution to target sites of substrate drugs. This raises the question of whether genetic variations in these transporters affect efficacy and risk of adverse events associated with metformin use. In this review, the pharmacogenetics of metformin is discussed in the light of the most recent literature. Overall, results from healthy volunteers support the notion that metformin pharmacokinetics can be affected by polymorphisms in genes encoding organic cation transporters. When considering the glycemic response to metformin in patients, however, the likely multifactorial nature of metformin response masks the effects of transporter polymorphisms observed in some clinical studies.

Cellular and molecular mechanisms of metformin: an overview

Considerable efforts have been made since the 1950s to better understand the cellular and molecular mechanisms of action of metformin, a potent antihyperglycaemic agent now recommended as the first-line oral therapy for T2D (Type 2 diabetes). The main effect of this drug from the biguanide family is to acutely decrease hepatic glucose production, mostly through a mild and transient inhibition of the mitochondrial respiratory chain complex I. In addition, the resulting decrease in hepatic energy status activates AMPK (AMP-activated protein kinase), a cellular metabolic sensor, providing a generally accepted mechanism for the action of metformin on hepatic gluconeogenesis. The demonstration that respiratory chain complex I, but not AMPK, is the primary target of metformin was recently strengthened by showing that the metabolic effect of the drug is preserved in liver-specific AMPK-deficient mice. Beyond its effect on glucose metabolism, metformin has been reported to restore ovarian function in PCOS (polycystic ovary syndrome), reduce fatty liver, and to lower microvascular and macrovascular complications associated with T2D. Its use has also recently been suggested as an adjuvant treatment for cancer or gestational diabetes and for the prevention in pre-diabetic populations. These emerging new therapeutic areas for metformin will be reviewed together with recent findings from pharmacogenetic studies linking genetic variations to drug response, a promising new step towards personalized medicine in the treatment of T2D.

Anticancer effects of metformin and its potential use as a therapeutic agent for breast cancer

Metformin is an orally available, biguanide derivative that is widely used in the treatment of Type 2 diabetes. Recent preclinical data have demonstrated that it can also act as an anticancer agent by activation of AMPK and subsequent inhibition of mTOR. Metformin is currently being investigated in several Phase II/III clinical trials. This article will review the current evidence for its mechanism of action, efficacy in preclinical and clinical models, and toxicity. Ongoing and planned studies evaluating the impact of metformin on breast cancer outcomes are also discussed.

Prognostic value of total testosterone for pregnancy during treatment in patients with clomiphene-citrate-resistant polycystic ovary syndrome: a pilot study

PURPOSE

Reduction of serum total testosterone (TT) is associated with pregnancy rate in polycystic ovary syndrome (PCOS) women receiving metformin, but most of the studies focus on the changes of basal levels of TT. The aim of this study was to evaluate whether the TT level around the ovulation period is related to the outcome of pregnancy in women with PCOS.

METHODS

In total, 30 non-obese PCOS women with clomiphene citrate (CC) resistance from the Medical College's Reproductive Health Center were enrolled and randomly assigned to be treated with placebo (Group 1) or metformin (850 mg) (Group 2) twice daily for 3 months as the pre-treatment. Then, metformin alone was administered with CC, human menopausal gonadotropin (HMG) and human chorionic gonadotropin (HCG) to induce ovulation for 3 months in Group 1. In Group 2, CC/HMG/HCG was used to induce ovulation for 3 months without metformin. Follicle-stimulating hormone, luteinizing hormone, estradiol and TT levels before and after ovulation in pregnant cycles and non-pregnant cycles were evaluated over the course of treatment.

RESULTS

A total of 26 subjects completed 65 cycles. The TT levels after ovulation in the pregnant cycles were significantly lower than in the non-pregnant cycles in both groups (P = 0.001 and P < 0.001, respectively).

CONCLUSIONS

The level of TT after ovulation may be of prognostic value for pregnancy in non-obese women with PCOS and CC resistance during treatment.

Metformin therapy in a hyperandrogenic anovulatory mutant murine model with polycystic ovarian syndrome characteristics improves oocyte maturity during superovulation

Background

Metformin, an oral biguanide traditionally used for the treatment of type 2 diabetes, is widely used for the management of polycystic ovary syndrome (PCOS)-related anovulation. Because of the significant prevalence of insulin resistance and glucose intolerance in PCOS patients, and their putative role in ovulatory dysfunction, the use of metformin was touted as a means to improve ovulatory function and reproductive outcomes in PCOS patients. To date, there has been inconsistent evidence to demonstrate a favorable effect of metformin on oocyte quality and competence in women with PCOS. Given the heterogeneous nature of this disorder, we hypothesized that metformin may be beneficial in mice with aberrant metabolic characteristics similar to a significant number of PCOS patients. The aim of this study was to gain insight into the in vitro and in vivo effects of metformin on oocyte development and ovulatory function.

Methods

We utilized metformin treatment in the transgenic ob/ob and db/db mutant murine models which demonstrate metabolic and reproductive characteristics similar to women with PCOS. Results: Metformin did not improve in vitro oocyte maturation nor did it have an appreciable effect on in vitro granulosa cell luteinization (progesterone production) in any genotype studied. Although both mutant strains have evidence of hyperandrogenemia, anovulation, and hyperinsulinemia, only db/db mice treated with metformin had a greater number of mature oocytes and total overall oocytes compared to control. There was no observed impact on body mass, or serum glucose and androgens in any genotype.

Conclusions

Our data provide evidence to suggest that metformin may optimize ovulatory performance in mice with a specific reproductive and metabolic phenotype shared by women with PCOS. The only obvious difference between the mutant murine models is that the db/db mice have elevated leptin levels raising the questions of whether their response to metformin is related to elevated leptin levels and/or if a subset of PCOS women with hyperleptinemia may be responsive to metformin therapy. Further study is needed to better define a subset of women with PCOS that may be responsive to metformin.

Fertility treatment in women with polycystic ovary syndrome: a decision analysis of different oral ovulation induction agents

OBJECTIVE

To compare different oral ovulation induction agents in treating infertile women with polycystic ovary syndrome (PCOS).

DESIGN

Decision-analytic model comparing three treatment strategies using probability estimates derived from literature review and sensitivity analyses performed on the baseline assumptions.

SETTING

Outpatient reproductive medicine and gynecology practices.

PATIENT(S)

Infertile women with PCOS.

INTERVENTION(S)

Metformin, clomiphene citrate, or metformin with clomiphene citrate.

MAIN OUTCOME MEASURE(S)

Live birth.

RESULT(S)

Within the baseline assumptions, combination therapy with metformin and clomiphene citrate was the preferred therapy for achieving live birth in women with PCOS. Sensitivity analysis revealed the model to be robust over a wide range of probabilities.

CONCLUSION(S)

Combination therapy with metformin and clomiphene citrate should be considered as first-line treatment for infertile women with PCOS.