Metformin Response Research Articles

Quantitative In Vivo Proteomics of Metformin Response in Liver Reveals AMPK-Dependent and -Independent Signaling Networks

Metformin is the front-line treatment for type 2 diabetes worldwide. It acts via effects on glucose and lipid metabolism in metabolic tissues, leading to enhanced insulin sensitivity. Despite significant effort, the molecular basis for metformin response remains poorly understood, with a limited number of specific biochemical pathways studied to date. To broaden our understanding of hepatic metformin response, we combine phospho-protein enrichment in tissue from genetically engineered mice with a quantitative proteomics platform to enable the discovery and quantification of basophilic kinase substrates invivo. We define proteins whose binding to 14-3-3 are acutely regulated by metformin treatment and/or loss of the serine/threonine kinase, LKB1. Inducible binding of 250 proteins following metformin treatment is observed, 44% of which proteins bind in a manner requiring LKB1. Beyond AMPK, metformin activates protein kinase D and MAPKAPK2 in an LKB1-independent manner, revealing additional kinases that may mediate aspects of metformin response. Deeper analysis uncovered substrates of AMPK in endocytosis and calcium homeostasis.

Metformin strongly affects transcriptome of peripheral blood cells in healthy individuals.

Metformin is a commonly used antihyperglycaemic agent for the treatment of type 2 diabetes mellitus. Nevertheless, the exact mechanisms of action, underlying the various therapeutic effects of metformin, remain elusive. The goal of this study was to evaluate the alterations in longitudinal whole-blood transcriptome profiles of healthy individuals after a one-week metformin intervention in order to identify the novel molecular targets and further prompt the discovery of predictive biomarkers of metformin response. Next generation sequencing-based transcriptome analysis revealed metformin-induced differential expression of genes involved in intestinal immune network for IgA production and cytokine-cytokine receptor interaction pathways. Significantly elevated faecal sIgA levels during administration of metformin, and its correlation with the expression of genes associated with immune response (CXCR4, HLA-DQA1, MAP3K14, TNFRSF21, CCL4, ACVR1B, PF4, EPOR, CXCL8) supports a novel hypothesis of strong association between metformin and intestinal immune system, and for the first time provide evidence for altered RNA expression as a contributing mechanism of metformin’s action. In addition to universal effects, 4 clusters of functionally related genes with a subject-specific differential expression were distinguished, including genes relevant to insulin production (HNF1B, HNF1A, HNF4A, GCK, INS, NEUROD1, PAX4, PDX1, ABCC8, KCNJ11) and cholesterol homeostasis (APOB, LDLR, PCSK9). This inter-individual variation of the metformin effect on the transcriptional regulation goes in line with well-known variability of the therapeutic response to the drug.

Common Variants in 22 Genes Regulate Response to Metformin Intervention in Children with Obesity: A Pharmacogenetic Study of a Randomized Controlled Trial.

Metformin is a first-line oral antidiabetic agent that has shown additional effects in treating obesity and metabolic syndrome. Inter-individual variability in metformin response could be partially explained by the genetic component. Here, we aimed to test whether common genetic variants can predict the response to metformin intervention in obese children. The study was a multicenter and double-blind randomized controlled trial that was stratified according to sex and pubertal status in 160 children with obesity. Children were randomly assigned to receive either metformin (1g/d) or placebo for six months after meeting the defined inclusion criteria. We conducted a post hoc genotyping study in 124 individuals (59 placebo, 65 treated) comprising finally 231 genetic variants in candidate genes. We provide evidence for 28 common variants as promising pharmacogenetics regulators of metformin response in terms of a wide range of anthropometric and biochemical outcomes, including body mass index (BMI) Z-score, and glucose, lipid, and inflammatory traits. Although no association remained statistically significant after multiple-test correction, our findings support previously reported variants in metformin transporters or targets as well as identify novel and promising loci, such as the ADYC3 and the BDNF genes, with plausible biological relation to the metformin’s action mechanism. Trial Registration: Registered on the European Clinical Trials Database (EudraCT, ID: 2010-023061-21) on 14 November 2011 (URL: https://www.clinicaltrialsregister.eu/ctr-search/trial/2010-023061-21/ES).

Pharmacogenetics of Metformin for Medication-Induced Weight Gain in Autism Spectrum Disorder.

Objectives: We recently found that metformin attenuated weight gain due to mixed dopamine and serotonin receptor antagonists, commonly termed atypical antipsychotics, in children and adolescents with autism spectrum disorder (ASD). Previous studies have found that genetic variation predicts response to metformin in diabetes. In this study, we aimed to assess whether response to metformin for weight gain in this population is associated with variants in five genes previously implicated in metformin response in diabetes. Methods: Youth with ASD who experienced significant weight gain while taking mixed receptor antagonist medications were randomly assigned to metformin or placebo for 16 weeks, followed by open-label metformin treatment for 16 weeks. In the 53 participants with available DNA samples, we used a linear, mixed model analysis to assess response in the first 16 weeks of metformin treatment, whether in the randomized or open-label period, based upon genotypes at polymorphisms in five genes previously associated with metformin response in diabetes: ATM, SLC2A2, MATE1, MATE2, and OCT1. Results: In the primary analysis, both ATM and OCT1 showed significant effects of genotype on change in body mass index z-scores, the primary outcome measure, during the first 16 weeks of treatment with metformin. No other polymorphism showed a significant difference. Conclusion: As has been shown for metformin treatment in diabetes, genetic variation may predict response to metformin for weight gain in youth with ASD treated with mixed receptor antagonists. Further work is needed to replicate these findings and evaluate whether they can be used prospectively to improve outcomes.

Targeting Endometrial Cancer Stem Cell Activity with Metformin Is Inhibited by Patient-Derived Adipocyte-Secreted Factors.

Advanced endometrial cancer continues to have a poor prognosis, due to limited treatment options, which may be further adversely impacted by obesity. Endometrial cancer stem cells have been reported to drive metastasis, chemotherapy resistance and disease relapse, but have yet to be fully characterised and no specific targeted therapies have been identified. Here, we describe the phenotype and genotype of aldehyde dehydrogenase high (ALDHhigh) and CD133+ve endometrial cancer stem cells and how adipocyte secreted mediators block the inhibitory effect of metformin on endometrial cancer stem cell activity. Ishikawa and Hec-1a cell lines were used to characterise ALDHhigh and CD133+ve endometrial cancer cells using flow cytometry, functional sphere assays and quantitative-Polymerase Chain Reaction. The comparative effect of metformin on endometrial cancer stem cell activity and bulk tumour cell proliferation was determined using an Aldefluor and cytotoxicity assay. The impact of adipocyte secreted mediators on metformin response was established using patient-derived conditioned media. ALDHhigh cells demonstrated greater endometrial cancer stem cell activity than CD133+ve cells and had increased expression of stem cell and epithelial-mesenchymal transition genes. Treatment with 0.5–1 mM metformin reduced the proportion and activity of both endometrial cancer stem cell populations (p ≤ 0.05), without affecting cell viability. This effect was, however, inhibited by exposure to patient-derived adipocyte conditioned media. These results indicate a selective and specific effect of metformin on endometrial cancer stem cell activity, which is blocked by adipocyte secreted mediators. Future studies of metformin as an adjuvant therapy in endometrial cancer should be adequately powered to investigate the influence of body mass on treatment response.

Effects of TCF7L2 rs7903146 variant on metformin response in patients with type 2 diabetes.

The response to metformin, the most commonly used drug for the treatment of type 2 diabetes (T2D), is highly variable. The common variant rs7903146 C>T within the transcription factor 7-like 2 gene (TCF7L2) is the strongest genetic risk factor associated with T2D to date. In this study, we explored the effects of the TCF7L2 rs7903146 genotype on metformin response in T2D. The study included 86 newly diagnosed patients with T2D, incident users of metformin. Levels of fasting glucose, insulin, HbA1c, total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, and anthropometric parameters were measured prior to metformin therapy, and 6 and 12 months after the treatment. Genotyping of the TCF7L2 rs7903146 was performed by the Sequenom MassARRAY® iPLEX® platform. At baseline, the diabetes risk allele (T) showed an association with lower triglyceride levels (p = 0.037). After 12 months of metformin treatment, the T allele was associated with 25.9% lower fasting insulin levels (95% CI 10.9-38.3%, p = 0.002) and 29.1% lower HOMA-IR index (95% CI 10.1-44.1%, p = 0.005), after adjustment for baseline values. Moreover, the T allele was associated with 6.7% lower fasting glucose levels (95% CI 1.1-12.0%, p = 0.021), adjusted for baseline glucose and baseline HOMA-%B levels, after 6 months of metformin treatment. This effect was more pronounced in the TT carriers who had 16.8% lower fasting glucose levels (95% CI 7.0-25.6%, p = 0.002) compared to the patients with CC genotype. Our results suggest that the TCF7L2 rs7903146 variant affects markers of insulin resistance and glycemic response to metformin in newly diagnosed patients with T2D within the first year of metformin treatment.

Metformin use in hidradenitis suppurativa

Background: Hidradenitis suppurativa (HS) is a chronic debilitating inflammatory disease, associated with metabolic syndrome, obesity and insulin resistance. Metformin, an oral hypoglycaemic agent, may play an important role in delaying or preventing the onset of diabetes and metabolic syndrome. Metformin has been reported as having efficacy in HS. It may have a role in the treatment of HS and its associated co-morbidities.Objective: To evaluate metformin use, response and tolerability in a HS population.Methods: A retrospective chart review of patients attending a specialist Dermatology HS clinic over 12 months. All patients treated with metformin were included.Results: Fifty-three HS patients received metformin; 85% female; mean age was 37 years and mean weight was 102 kg. The mean duration of metformin was 11.3 months and mean dose was 1.5 g/days. The 6- and 12-month drug survival were 61% and 39%, respectively. Metformin was well tolerated. Gastrointestinal side effects were experienced by 11%. Subjective clinical response was seen in 68% (n = 36) with 19% (7/36) of these having quiescent disease with metformin monotherapy. 25% had no improvement. Insulin resistance was seen in 75%. Its presence did not predict clinical response to metformin.Conclusion: Metformin is an effective, well tolerated and inexpensive treatment that represents a viable treatment option for HS.Key message: Metformin is an effective; well tolerated and inexpensive treatment in the management of HS.

The novel function of tumor protein D54 in regulating pyruvate dehydrogenase and metformin cytotoxicity in breast cancer

BackgroundThe role of tumor protein D54 in breast cancer has not been studied and its function in breast cancer remains unclear. In our previous pharmacogenomic studies using lymphoblastoid cell line (LCL), this protein has been identified to affect metformin response. Although metformin has been widely studied as a prophylactic and chemotherapeutic drug, there is still a lack of biomarkers predicting the response to metformin in breast cancer. In this study, we revealed the novel function of TPD54 in breast cancer through understanding how TPD54 altered the cancer cell sensitivity to metformin.MethodsThe role of TPD54 in altering cellular sensitivity to metformin treatment was carried out by either knockdown or overexpression of TPD54, followed by measuring cell viability and reactive oxygen species (ROS) production in MCF7 breast cancer cell line and breast cancer patient-derived xenografts. Functional analysis of TPD54 in breast cancer cells was demonstrated by studying TPD54 protein localization and identification of potential binding partners of TPD54 through immunoprecipitation followed by mass spectrometry. The effect of TPD54 on pyruvate dehydrogenase (PDH) protein regulation was demonstrated by western blot, immunoprecipitation, and site-directed mutagenesis.ResultsTPD54 inhibited colony formation and enhanced cellular sensitivity to metformin treatment in MCF7 cells and breast cancer patient-derived xenografts. Mechanistic study indicated that TPD54 had mitochondrial localization, bound to and stabilized pyruvate dehydrogenase E1α by blocking pyruvate dehydrogenase kinase 1 (PDK1)-mediated serine 232 phosphorylation. TPD54 knockdown increased PDH E1α protein degradation and led to decreased PDH enzyme activity, which reduced mitochondrial oxygen consumption and reactive oxygen species (ROS) production, thus contributing to the resistance of breast cancer cells to metformin treatment.ConclusionWe have discovered a novel mechanism by which TPD54 regulates pyruvate dehydrogenase and affects the sensitivity of breast cancer to metformin treatment. Our findings highlight the important post-translational regulation of PDK1 on PDH E1α and the potential application of TPD54 as a biomarker for selecting tumors that may be sensitive to metformin therapy. These provide new insights into understanding the regulation of PDH complexes and the resistance mechanisms of cancer cells to metformin treatment.

Variability in the therapeutic response of Metformin treatment in patients with type 2 diabetes mellitus.

Objective:To assess the glycemic response of metformin in patients with Type-2 Diabetes Mellitus (T2DM) as well as to see its association with reductions in BMI and GIT intolerance.Methods:This Quasi, Experimental study was conducted at Jinnah-Allama Iqbal Institute of Diabetes and Endocrinology (JAIDE) Jinnah Hospital, Lahore from 1st March 2016 to 30th September 2016. Newly diagnosed T2DM patients were given metformin for duration of three months and later on they were categorized into Responders and Non-Responders on the basis of HbA1c (A1C) reductions, which were estimated by Hemoglobin (A1C) analyzer (TD4611A TAIDoc Tech. Taiwan) through photometry. Similarly, baseline BMI and BMI after three months therapy with metformin was also recorded.Results:Among total of 200 patients, 40.5% of the patients were classified as Non-Responders whereas; 59.5% of the patients as Responders. The baseline BMI (26.09 kg/m2) was also decreased significantly after metformin therapy (25.40 kg/m2). It was found that metformin reduced the A1C in all the patients. However, the glycemic control was much better in patients with higher baseline A1C (1.13% ± 0.08) as compared to lower baseline levels (0.61% ± 0.07). Regarding GIT intolerance, 140 patients lacked the symptoms, out of which 60.7% were responders and 39.3% were non-responders.Conclusions:Metformin lead to improvement in glycemic control in 59.5% of newly diagnosed T2DM patients after taking metformin for three months but in 40.5% it did not which may be because of combined effects of various gene polymorphisms and their interaction with non-genetic factors. Metformin reduced the BMI in all the patients; however, BMI lowering activity of metformin was same regardless of its effect on HbA1C. Moreover, the signs and symptoms of GIT intolerance did not differ between the two groups.

Genome editing of LKB1 (STK11) mutation in A549 lung cancer cells using CRISPR/Cas9 system

Mutations and deletions of the tumor suppressor LKB1 (STK11) are common in several malignancies, especially in non-small lung cancer cells (NSCLC). In that cell type, LKB1 inactivation coexists with mutations at other important cancer genes, including KRAS and TP53. The mutant LKB1 indirectly increases transcription of genes involved in metastasis, including COX-2. LKB1 directly activates AMPK decreasing mTOR activity and plays roles in several other processes such as cell metabolism, cell polarity, apoptosis and DNA damage via p53 interaction. Metformin, an antidiabetic drug, have shown antitumor effects, sensitizes cells in coadjuvant cisplatin treatment and acts in AMPK independent and dependent mechanisms. Thus, we propose the application of CRISPR/Cas9 system as genome editing tool to correct the LKB1 nonsense mutation and restore protein expression, providing new insights regarding cisplatin resistance, survival and metformin response in A549 lung cancer cells.

Genetic polymorphisms of organic cation transporters 1 (OCT1) and responses to metformin therapy in individuals with type 2 diabetes mellitus: a systematic review protocol

BackgroundMetformin is one of the most commonly used drugs for type 2 diabetes mellitus (T2DM). Despite its efficacy and safety, metformin is frequently associated with highly variable glycemic responses, which is hypothesized to be the result of genetic variations in its transport by organic cation transporters (OCTs). This systematic review aims to highlight and summarize the overall effects of OCT1 polymorphisms on therapeutic responses to metformin and to evaluate their potential role in terms of interethnic differences with metformin responses.Methods/designWe will systematically review observational studies reporting on the genetic association between OCT1 polymorphisms and metformin responses in T2DM patients. A comprehensive search strategy formulated with the help of a librarian will be used to search MEDLINE via PubMed, Embase, and CINAHL for relevant studies published between January 1990 and July 2017. Two review authors will independently screen titles and abstracts in duplicate, extract data, and assess the risk of bias with discrepancies resolved by discussion or arbitration of a third review author. Mined data will be grouped according to OCT1 polymorphisms, and their effects on therapeutic responses to metformin will be narratively synthesized. If sufficient numbers of homogeneous studies are scored, meta-analyses will be performed to obtain pooled effect estimates. Funnel plots analysis and Egger’s test will be used to assess publication bias. This study will be reported according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines.DiscussionThis review will summarize the genetic effects of OCT1 polymorphisms associated with variabilities in glycemic responses to metformin. The findings of this study could help to develop genetic tests that could predict a person’s response to metformin treatment and create personalized drugs with greater efficacy and safety.Systematic review registrationRegistration number: PROSPERO, CRD42017079978

Evaluation of the rs3088442 G>A SLC22A3 Gene Polymorphism and the Role of microRNA 147 in Groups of Adult Pakistani Populations With Type 2 Diabetes in Response to Metformin.

Type 2 diabetes is a complex genetic disorder, and a large number of genetic polymorphisms may be involved in its pathogenesis. Pharmacologically, type 2 diabetes can be treated with 9 different approved classes of drugs, but metformin is suggested as the first line of therapy, followed by sulfonylureas. This was a case-control study consisting of 300 metformin responders and 300 metformin nonresponders in patients with type 2 diabetes and 300 healthy Pakistani subjects. Genotyping of the SLC22A3 G>A polymorphism was performed by allele-specific polymerase chain reaction (PCR) for microRNA 147 expression; real-time polymerase chain reaction was used, and expressional analysis of SLC22A3 was done by semiquantitative polymerase chain reaction. GA and AA genotypes were highly significantly associated with the drug treatments when compared with controls. A statistically significant difference was observed in the distribution of the SLC22A3 A allele between healthy subjects and patients with type 2 diabetes. When odds ratios were adjusted for glycated hemoglobin levels and postprandial and fasting blood glucose levels, our findings showed that the overexpression of allele A of the rs3088442 G>A variant may act as a protective allele and is associated with the clinical response to metformin. microRNA 147 expression was found to be increased in patients who were metformin responders compared with the nonresponder group and controls. mRNA expression of SLC22A3 was significantly reduced in patients taking metformin as compared to other groups. These results suggested that the SLC22A3 rs3088442 at position 2282 A allele may confer metformin clinical responses in patients with type 2 diabetes in the Pakistani population. Overexpression of microRNA 147 is associated with a downward expression of the SLC22A3 gene in patients who have type 2 diabetes.

Genetic polymorphisms of organic cation transporter 1 (OCT1) and responses to metformin therapy in individuals with type 2 diabetes: A systematic review.

Background:Metformin is one of the most commonly used drugs for the treatment of type 2 diabetes mellitus (T2DM). Despite its widespread use, there are considerable interindividual variations in metformin response, with about 35% of patients failing to achieve initial glycemic control. These variabilities that reflect phenotypic differences in drug disposition and action may indeed be due to polymorphisms in genes that regulate pharmacokinetics and pharmacodynamics of metformin. Moreover, interethnic differences in drug responses in some cases correspond to substantial differences in the frequencies of the associated pharmacogenomics risk allele.Aim:This study aims to highlight and summarize the overall effects of organic cation transporter 1(OCT1) polymorphisms on therapeutic responses to metformin and to evaluate the potential role of such polymorphisms in interethnic differences in metformin therapy.Methods:We conducted a systematic review according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. We searched for PubMed/MEDLINE, Embase, and CINAHL, relevant studies reporting the effects of OCT1 polymorphisms on metformin therapy in T2DM individuals. Data were extracted on study design, population characteristics, relevant polymorphisms, measure of genetic association, and outcomes. The presence of gastrointestinal side effects, glycated hemoglobin A1 (HbA1c) levels, fasting plasma glucose (FPG), and postprandial plasma glucose (PPG) concentrations after treatment with metformin were chosen as measures of the metformin responses. This systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO).Results:According to the data extracted, a total of 34 OCT1 polymorphisms were identified in 10 ethnic groups. Significant differences in the frequencies of common alleles were observed among these groups. Met408Val (rs628031) variant was the most extensively explored with metformin responses. Although some genotypes and alleles have been associated with deleterious effects on metformin response, others indeed, exhibited positive effects.Conclusion:Genetic effects of OCT1 polymorphisms on metformin responses were population specific. Further investigations in other populations are required to set ethnicity-specific reference for metformin responses and to obtain a solid basis to design personalized therapeutic approaches for T2DM treatment.

A Pharmacometabolomic Approach to Predict Response to Metformin in Early-Phase Type 2 Diabetes Mellitus Patients.

Metformin is a first-line medication for type 2 diabetes mellitus (T2DM). Based on its universal use, the consideration of inter-individual variability and development of predictive biomarkers are clinically significant. We aimed to identify endogenous markers of metformin responses using a pharmacometabolomic approach. Twenty-nine patients with early-phase T2DM were enrolled and orally administered metformin daily for 6 months. A total of 22 subjects were included in the final analysis. Patients were defined as responders or non-responders based on changes in their glycated haemoglobin A1c (HbA1c) from baseline, over 3 months. Urine metabolites at baseline, as well as at the 3 and 6 month follow-ups after the start of treatment were analysed using gas chromatography-mass spectrometry and evaluated with multivariate analyses. Metabolites distinguishable between the two response groups were obtained at baseline, as well as at the 3 and 6 month follow-ups, and significantly different metabolites were listed as markers of metformin response. Among the identified metabolites, citric acid, myoinositol, and hippuric acid levels showed particularly significant differences between the non-responder and responder groups. We thus identified different metabolite profiles in the two groups of T2DM patients after metformin administration, using pharmacometabolomics. These results might facilitate a better understanding and prediction of metformin response and its variability in individual patients.

Genetic Variants in CPA6 and PRPF31 Are Associated With Variation in Response to Metformin in Individuals With Type 2 Diabetes.

Metformin is the first-line treatment for type 2 diabetes (T2D). Although widely prescribed, the glucose-lowering mechanism for metformin is incompletely understood. Here, we used a genome-wide association approach in a diverse group of individuals with T2D from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) clinical trial to identify common and rare variants associated with HbA1c response to metformin treatment and followed up these findings in four replication cohorts. Common variants in PRPF31 and CPA6 were associated with worse and better metformin response, respectively (P < 5 × 10-6), and meta-analysis in independent cohorts displayed similar associations with metformin response (P = 1.2 × 10-8 and P = 0.005, respectively). Previous studies have shown that PRPF31(+/-) knockout mice have increased total body fat (P = 1.78 × 10-6) and increased fasted circulating glucose (P = 5.73 × 10-6). Furthermore, rare variants in STAT3 associated with worse metformin response (q <0.1). STAT3 is a ubiquitously expressed pleiotropic transcriptional activator that participates in the regulation of metabolism and feeding behavior. Here, we provide novel evidence for associations of common and rare variants in PRPF31, CPA6, and STAT3 with metformin response that may provide insight into mechanisms important for metformin efficacy in T2D.

Emerging Clinical Importance of Hepatic Organic Cation Transporter 1 (OCT1) in Drug Pharmacokinetics, Dynamics, Pharmacogenetic Variability, and Drug Interactions.

Hepatic organic cation transporter 1 (OCT1) can be a determinant of drug clearance and distribution, which can impact drug exposure and response. OCT1 was shown recently to be the rate-determining step in the clearance of several drugs in humans, and thereby a mechanism of pharmacogenetic variability and drug-drug interactions (DDIs). OCT1 mediates metformin distribution to the liver (key biophase). As OCT1 modulation impacts metformin response, but not pharmacokinetics (PK), metformin DDI studies require pharmacodynamic endpoint(s) to inform rational metformin dose adjustment.

The Pharmacogenetics of Metformin in Women with Polycystic Ovary Syndrome: A Randomized Trial.

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder affecting women of reproductive age. PCOS is associated with obesity, dyslipidaemia and insulin resistance, and metformin treatment may improve such metabolic features. The effect of genetic variants in key metformin transporters, their transcriptional regulators or in metformin target genes on metformin response in women with PCOS is unclear. Associations between pharmacodynamic responses to metformin (changes in weight, lipid profile, insulin sensitivity evaluated by oral glucose tolerance testing) and polymorphisms in OCT1 (rs12208357 and rs72552763), HNF1A (rs1169288 and rs2464196), MATE1 (rs2289669 and rs2252281), MATE2-K (rs12943590) and ATM (rs11212617) were studied in 40 women with PCOS randomized to 12 months of treatment with metformin 1000 mg twice daily ± oral contraceptive pills (150 μg desogestrel + 30 μg ethinylestradiol). In the entire study population, treatment was associated with reduced weight (median weight change -2.4 kg, 25th-75th percentile -5.2 to 0.3 kg, p < 0.001) and increased triglycerides (0.2 mmol/L (0.0-0.6 mmol/L), p < 0.01) without significant changes in other lipid parameters or insulin sensitivity (insulinAUC , glucoseAUC during OGTT). None of the evaluated polymorphisms significantly affected any treatment outcome. In conclusion, the genetic variants investigated were not crucial for the clinical response to metformin in PCOS.

The pharmacogenetics of metformin.

Despite its widespread use as the first-line agent for the treatment of type 2 diabetes, it has become clear that metformin does not work optimally for everyone. Elucidating who are the likely metformin responders and non-responders is hampered by our limited knowledge of its precise molecular mechanism of action. One approach to achieve the related goals of stratifying patients into response subgroups and identifying the molecular targets of metformin involves the deployment of agnostic genome-wide approaches in cohorts of appropriate size to attain sufficient statistical power. While candidate gene studies have shed some light on the role of genetic variation in influencing metformin response, genome-wide association studies are beginning to provide additional insight that is unconstrained by prior knowledge. To fully realise their potential, much larger samples need to be assembled via international collaboration, preferably involving the academic community, government and the pharmaceutical industry.

BIOEQUIVALENCE STUDY OF ANTIDIABETIC ACTIVITY BETWEEN TWO MARKETED FORMULATIONS OF METFORMIN ON GLUCOCORTICOID-INDUCED HYPERGLYCEMIA IN RABBIT

Objective: Bioequivalence studies are the commonly accepted methods displaying therapeutic equivalence between two products. This study was conducted to evaluate the bioequivalence study of anti-diabetic activity between two formulations of metformin tablets which were marketed in India.Methods: In in vitro study five essential in vitro tests including disintegration, weight variation, hardness, friability and a comparative in vitro dissolution study were performed.Results: For in vivo study adult male rabbits were divided into three groups of two each. The first group is regarded as control group received 3 ml of normal saline daily by using the gastric tube for 15 d and the second and third group received (0.35 mg/Kg B.W. single dosage) of dexamethasone tablets which were powdered, dissolved in 3 ml of normal saline daily for 15 d. After 15 d the blood glucose of second and third group was estimated and after that received formulation X and formulation Y, dissolved in 3 ml of normal saline daily for 15 d at the dose of 0.5 gm/kg body weight orally. After 15 d again blood glucose of second and third group was estimated and compare the results of both the group. This shows the favourable response of metformin against glucocorticoid-induced renal damage and hyperglycemia.Conclusion: Results of this study showed that the extent, rate of absorption and anti-diabetic activity of two different formulations of metformin tablets are bioequivalent to each other.

Abstract 12: Evaluation of metformin and clotam combination for medulloblastoma

Abstract Medulloblastoma (MB) is the most common malignant brain tumor in children. Standard treatment, which includes surgery, chemotherapy, and radiation, is successful for most patients, but survivors often suffer from significant long-term side effects affecting their neurocognitive and growth potential. Therefore, there is a critical need to understand the molecular processes that regulate MB growth and find less toxic therapies. Survivin (BIRC5) was identified as a protein belonging to the Inhibitor of Apoptosis Protein family that inhibits apoptosis by inhibiting caspase activation. Survivin expression is also associated with increased resistance of tumor cells to radiation and chemotherapy. In MB, several studies suggest that increased expression of survivin serves as a marker of tumor morphology and is associated with poor prognosis. Specificity protein 1 (Sp1) is one of the transcription factors that regulates the expression of survivin gene. Sp1 is also shown to be overexpressed in some cancer cells and is associated with poor prognosis. In this study, we are testing a strategy of targeting survivin in MB using anti-diabetic drug Metformin, which targets Sp1, and the NSAID Clotam (Tolfenamic acid, TA), which targets Sp1 and survivin. Dose response curves were established by treating MB cell lines DAOY and D283 with increasing concentrations of metformin or TA and measuring cell viability at 24 and 48h post-treatment using the CellTiter-Glo Cell Viability Assay. A time and dose dependent inhibition of cell proliferation was observed for both the drugs. Metformin dose response was then repeated in the presence of 25 or 50 µM TA. Our results indicate that TA significantly increased the growth inhibitory response of metformin. To further characterize this response, we determined the combination index (CI) using the Chou-Talalay method. We found that the CI values were between 0.85 to 0.61 for various combinations of metformin and TA, strongly suggesting a synergistic effect of the two drugs on cell proliferation. Combination of metformin and TA was also accompanied by a 3-4 fold increase in apoptotic cells at 48h post-treatment, as determined by AnnexinV staining of DAOY cells. Western blot analysis of DAOY cells treated with the two drugs also revealed a decrease in survivin and Bcl-2 protein levels, and an increase in cleaved-PARP. In conclusion, the anticancer activity of metformin in MB cells is enhanced in the presence of TA. Both drugs synergistically combine to inhibit MB cell proliferation and increase apoptosis, which in part may be the result of a decrease in survivin levels. This combination strategy may therefore represent a novel targeted therapy for MB. Studies are underway to determine whether this drug combination can enhance the response of chemotherapy in MB cells, since both TA and metformin are known to sensitize cancer cells to chemotherapy. Citation Format: Umesh T. Sankpal, W Paul Bowman, Jeffrey C. Murray, Riyaz Basha. Evaluation of metformin and clotam combination for medulloblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 12. doi:10.1158/1538-7445.AM2017-12