Prevention of pancreatic cancer induction in hamsters by metformin

Metformin role in Parkinson's disease: a double-sword effect

Parkinson's disease (PD) is a common neurodegenerative disease developed due to the degeneration of dopaminergic neurons in the substantia nigra. There is no single effective treatment in the management of PD. Therefore, repurposing effective and approved drugs like metformin could be an effective strategy for managing PD. However, the mechanistic role of metformin in PD neuropathology was not fully elucidated. Metformin is an insulin-sensitizing agent used as a first-line therapy in the management of type 2 diabetes mellitus (T2DM) and has the ability to reduce insulin resistance (IR). Metformin may have a beneficial effect on PD neuropathology. The neuroprotective effect of metformin is mainly mediated by activating adenosine monophosphate protein kinase (AMPK), which reduces mitochondrial dysfunction, oxidative stress, and α-synuclein aggregation. As well, metformin mitigates brain IR a hallmark of PD and other neurodegenerative diseases. However, metformin may harm PD neuropathology by inducing hyperhomocysteinemia and deficiency of folate and B12. Therefore, this review aimed to find the potential role of metformin regarding its protective and detrimental effects on the pathogenesis of PD. The mechanistic role of metformin in PD neuropathology was not fully elucidated. Most studies regarding metformin and its effectiveness in PD neuropathology were observed in preclinical studies, which are not fully translated into clinical settings. In addition, metformin effect on PD neuropathology was previously clarified in T2DM, potentially linked to an increasing PD risk. These limitations hinder the conclusion concerning the therapeutic efficacy of metformin and its beneficial and detrimental role in PD. Therefore, as metformin does not cause hypoglycemia and is a safe drug, it should be evaluated in non-diabetic patients concerning PD risk.

The antiproliferative potential and mechanism of action of metformin in MCF-7 cells

Aim

The current study aimed to investigate the potential antiproliferative activity of metformin, the effective concentration range, and the mechanism of action.

Materials & methods

Human breast cancer cells, MCF-7 were treated with a serial dilution of metformin (10-150 μM) for 24 and 48 h. Potential antiproliferative activity of metformin and its ability in inducing cellular apoptosis and autophagy were also investigated.

Results

Metformin inhibited MCF-7 proliferation in a concentration and time dependent manner, with 80 μM as the most effective concentration. Compared with nontreated cells, metformin induced significant levels of autophagy and apoptosis, which were confirmed by the reduction of mTOR and BCL-2 protein expression.

Conclusion

The study confirms the antiproliferative activity of metformin, which may likely occur through AMPK signaling pathway.

Metformin: new applications for an old drug

Metformin is a biguanide, evolved as one of the most widely used medicines. The applications of this component include but are not limited to reducing blood glucose, weight loss, and polycystic ovary syndrome. Studies about other probable indications have emerged, indicating that this agent can also be utilized for other purposes. In this review, applications of metformin are noticed based on the current evidence. Metformin commonly is used as an off-label drug in non-alcoholic fatty liver disease (NAFLD), but it worsens inflammation and should not be used for this purpose, according to the latest research. Metformin decreased the risk of death in patients with liver cirrhosis. It is an effective agent in the prevention and improvement of survival in patients suffering hepatocellular carcinoma. There is evidence of the beneficial effects of metformin in colorectal cancer, early-stage prostate cancer, breast cancer, urothelial cancer, blood cancer, melanoma, and bone cancer, suggesting metformin as a potent anti-tumor agent. Metformin shows neuroprotective effects and provides a potential therapeutic benefit for mild cognitive impairment and Alzheimer's disease (AD). It also has been shown to improve mental function and reduce the incidence of dementia. Another condition that metformin has been shown to slow the progression of is Duchenne muscular dystrophy. Regarding infectious diseases, tuberculosis (TB) and coronavirus disease (COVID-19) are among the conditions suggested to be affected by metformin. The beneficial effects of metformin in cardiovascular diseases were also reported in the literature. Concerning renal function, studies showed that daily oral administration of metformin could ameliorate kidney fibrosis and normalize kidney structure and function. This study reviewed the clinical and preclinical evidence about the possible benefits of metformin based on recent studies. Numerous questions like whether these probable indications of metformin can be observed in non-diabetics, need to be described by future basic experiments and clinical studies.

The relationship between the use of metformin and the risk of pancreatic cancer in patients with diabetes: a systematic review and meta-analysis

OBJECTIVE

We aim to evaluate the relationship between the use of metformin and the risk of pancreatic cancer in type 2 diabetes patients.

METHOD

We systematically searched the observational studies on PubMed, Embase, Web of Science, Cochrane Library, clinicalrials.gov, and CNKI databases, extracted relevant data, combined the OR value and 95% CI using the random effect model, and conducted a sensitivity analysis, subgroup analysis, and meta-regression to evaluate the size and stability of this relationship.

RESULT

Twenty-nine studies from twenty-four articles met our inclusion criteria, including more than 2 million subjects. Overall analysis showed that compared with no use of metformin, the use of metformin could reduce the risk of pancreatic cancer in patients with type 2 diabetes (OR = 0.82, 95% CI (0.69, 0.98)). Subgroup analysis showed that compared with the use of hypoglycemic drugs, the use of metformin could reduce the risk of pancreatic cancer in patients with type 2 diabetes (OR = 0.79, 95% CI (0.66, 0.94)). However, compared with no drugs or only diet therapy, metformin users might increase the risk of pancreatic cancer (OR = 2.19, 95% CI (1.08, 4.44)). Sensitivity analysis confirmed the stability of the study, and there was no significant publication bias.

CONCLUSION

Compared with the no-use of metformin, metformin users with diabetes can reduce the risk of pancreatic cancer. More research is needed to prove it works.

Near-infrared phosphorescent cyclometalated platinum (II) and iridium (III) complexes with metformin moiety: Design and study towards anticancer theranostic agents

By rational altering the structure of CN auxiliary ligand, Near-infrared (NIR) phosphorescent cyclometalated platinum (II) and iridium (III) complexes with metformin (Met) have been successfully obtained and characterized. The dissociation of Met in aqueous solution can be accelerated by addition of Glutathione (GSH) and alleviated by drop of histidine, accompanied with a significant decay change of deep red phosphorescence. Besides, Pt3 and Ir1 with moiety of btpq mainly selectively targeted and located in Mitochondrial, while Pt1 of ppy and Pt2 with thpy mainly accumulated in endoplasmic reticulum. Moreover, Pt1-3 and Ir1 with metformin moiety all exert a significant enhanced anticancer activity, among them, Pt3 displays ca.66-fold, ca.147-fold and ca.588-fold higher cytotoxicity than cisplatin, Met-free analogue Pt3a and Met. Their relative anticancer mechanism was further investigated, both Pt2 and Pt3 could form covalent interaction with bovine serum albumin (BSA) and effectively induce reactive oxygen species (ROS) generation, arrest of cell cycle, loss of Mitochondrial membrane potential (MMP), display effective anti-metastasis activity and eventually induce apoptosis of cancer cell.

Inhibition of Heme Export and/or Heme Synthesis Potentiates Metformin Anti-Proliferative Effect on Cancer Cell Lines

Simple Summary

Tumor initiation and progression are sustained by the ability of the cancer cell to reshape its metabolism in a way that favors cell proliferation and survival. Recently, it was shown that heme metabolism contributes to metabolic adaptation of tumor cell and that interfering with heme homeostasis reduces tumor cell growth. Here, we show that the alteration of heme metabolism, either by RNA-interference or pharmacological approaches, increases the sensitivity of tumor cell lines to the antitumor agent metformin. These findings strengthen the concept of targeting heme metabolism to counteract tumor progression.

Abstract

Cancer is one of the leading causes of mortality worldwide. Beyond standard therapeutic options, whose effectiveness is often reduced by drug resistance, repurposing of the antidiabetic drug metformin appears promising. Heme metabolism plays a pivotal role in the control of metabolic adaptations that sustain cancer cell proliferation. Recently, we demonstrated the existence of a functional axis between the heme synthetic enzyme ALAS1 and the heme exporter FLVCR1a exploited by cancer cells to down-modulate oxidative metabolism. In colorectal cancer cell lines, the inhibition of heme synthesis-export system was associated with reduced proliferation and survival. Here, we aim to assess whether the inhibition of the heme synthesis-export system affects the sensitivity of colorectal cancer cells to metformin. Our data demonstrate that the inhibition of this system, either by blocking heme efflux with a FLVCR1a specific shRNA or by inhibiting heme synthesis with 5-aminolevulinic acid, improves metformin anti-proliferative effect on colorectal cancer cell lines. In addition, we demonstrated that the same effect can be obtained in other kinds of cancer cell lines. Our study provides an in vitro proof of concept of the possibility to target heme metabolism in association with metformin to counteract cancer cell growth.

Advances in metformin‑based metabolic therapy for non‑small cell lung cancer (Review)

Therapeutic approaches that target the metabolism of tumor cells have been a popular research topic in recent years. Previous studies have demonstrated that glycolysis inhibitors reduce the proliferation of non‑small cell lung cancer (NSCLC) cells by interfering with the aerobic glycolytic pathway. However, the mitochondrial oxidative phosphorylation (OXPHOS) pathway in tumor cells has also been implicated in lung cancer metabolism. Metformin, a known inhibitor of mitochondrial OXPHOS, has been indicated to reduce NSCLC morbidity and mortality in clinical studies. The present article reviewed the therapeutic effects of metformin against NSCLC, both as a single agent and combined with other anticancer treatments, in order to provide a theoretical basis for its clinical use in adjuvant therapy for NSCLC.

The effect of metformin on viability and mitochondrial status of tumor and non-tumor cell line

Introduction: Metformin is a drug of choice in the therapy of type II Diabetes mellitus. There is a growing evidence of metformin's antitumor activity, but the suggested mechanisms of such activity are still not fully elucidated. Aim: To investigate the effect of therapeutic doses of metformin on viability and mitochondrial status of human non-small cell lung carcinoma (NCI-H460) and human immortalized lung fibroblasts (MRC-5) cell lines. Material and methods: Acid phosphatase and Crystal Violet assays were used for the determination of NCI-H460 and MRC-5 cell viability after the treatment with metformin (10-60 µM) for 1-7 days. Mitochondrial membrane potential, production of reactive oxygen species and superoxide anion, as well as mitochondrial mass were measured using flow cytometry after the treatment of the cells for 3, 24 and 120 h, followed by staining with appropriate fluorochromes: JC-1, DHR, DHE and Mitotracker Red. Results: Metformin did not change the viability of both NCI-H460 and MRC-5 cells in all investigated time-points and all used concentrations. Depolarization of mitochondrial membrane was observed 3 h post-treatment in MRC-5 cells. Prolonged treatment (120 h) increased superoxide anion production and mitochondrial mass in NCI-H460 cells. No significant changes in production of reactive oxygen species were observed in both cells lines after short or extended exposure to metformin. Conclusion: : Therapeutic concentrations of metformin do not influence the viability of NCI-H460 and MRC-5 cells, but induce mitochondrial depolarization after short-term exposure in lung fibroblasts and increase production of superoxide anion and mitochondrial mass in lung carcinoma cells after prolonged treatment.

The role of AMPK/mTOR signaling pathway in anticancer activity of metformin

Metformin (MTF) is a widely used drug for the treatment of diabetes mellitus type 2 (DM2) and frequently used as an adjuvant therapy for polycystic ovarian syndrome, metabolic syndrome, and in some cases also tuberculosis. Its protective effect on the cardiovascular system has also been described. Recently, MTF was subjected to various analyzes and studies that showed its beneficial effects in cancer treatment such as reducing cancer cell proliferation, reducing tumor growth, inducing apoptosis, reducing cancer risk in diabetic patients, or reducing likelihood of relapse. One of the MTF's mechanisms of action is the activation of adenosine-monophosphate-activated protein kinase (AMPK). Several studies have shown that AMPK/mammalian target of rapamycin (mTOR) pathway has anticancer effect in vivo and in vitro. The aim of this review is to present the anticancer activity of MTF highlighting the importance of the AMPK/mTOR pathway in the cancer process.

Autophagy Modulators in Cancer: Focus on Cancer Treatment

Uncontrolled autophagy has been associated with the development and progression of various cancers that are resistant to cancer therapy. Therefore, many efforts to modulate uncontrolled autophagy as a cancer treatment have been attempted, from basic science to clinical trials. However, it remains difficult to equally apply autophagy modulators to cancer therapy because autophagy is a double-edged sword in cancer: it can be tumor-suppressive or tumor-protective. Therefore, the precise mechanisms of autophagy modulators and their varied responsiveness to each cancer type should be addressed in detail. This study will describe the precise mechanisms of developing various autophagy modulators, their current therapeutic applications and future perspectives.

Metformin: review of epidemiology and mechanisms of action in pancreatic cancer

Pancreatic ductal adenocarcinoma continues to be a lethal disease, for which efficient treatment options are very limited. Increasing efforts have been taken to understand how to prevent or intercept this disease at an early stage. There is convincing evidence from epidemiologic and preclinical studies that the antidiabetic drug metformin possesses beneficial effects in pancreatic cancer, including reducing the risk of developing the disease and improving survival in patients with early-stage disease. This review will summarize the current literature about the epidemiological data on metformin and pancreatic cancer as well as describe the preclinical evidence illustrating the anticancer effects of metformin in pancreatic cancer. Underlying mechanisms and targets of metformin will also be discussed. These include direct effects on transformed pancreatic epithelial cells and indirect, systemic effects on extra-pancreatic tissues.

Hyperinsulinemia in Obesity, Inflammation, and Cancer

The relative insufficiency of insulin secretion and/or insulin action causes diabetes. However, obesity and type 2 diabetes mellitus can be associated with an absolute increase in circulating insulin, a state known as hyperinsulinemia. Studies are beginning to elucidate the cause-effect relationships between hyperinsulinemia and numerous consequences of metabolic dysfunctions. Here, we review recent evidence demonstrating that hyperinsulinemia may play a role in inflammation, aging and development of cancers. In this review, we will focus on the consequences and mechanisms of excess insulin production and action, placing recent findings that have challenged dogma in the context of the existing body of literature. Where relevant, we elaborate on the role of specific signal transduction components in the actions of insulin and consequences of chronic hyperinsulinemia. By discussing the involvement of hyperinsulinemia in various metabolic and other chronic diseases, we may identify more effective therapeutics or lifestyle interventions for preventing or treating obesity, diabetes and cancer. We also seek to identify pertinent questions that are ripe for future investigation.

Biguanides: Species with versatile therapeutic applications

Biguanides are compounds in which two guanidine moieties are fused to form a highly conjugated system. Biguanides are highly basic and hence they are available as salts mostly hydrochloride salts, these cationic species have been found to exhibit many therapeutic properties. This review covers the research and development carried out on biguanides and accounts the various therapeutic applications of drugs containing biguanide group-such as antimalarial, antidiabetic, antiviral, anticancer, antibacterial, antifungal, anti-tubercular, antifilarial, anti-HIV, as well as other biological activities. The aim of this review is to compile all the medicinal chemistry applications of this class of compounds so as to pave way for the accelerated efforts in finding the drug action mechanisms associated with this class of compounds. Importance has been given to the organic chemistry of these biguanide derivatives also.

Metformin turns 62 in pharmacotherapy: Emergence of non-glycaemic effects and potential novel therapeutic applications

Metformin is the most commonly prescribed oral antidiabetic medication. Direct/indirect activation of Adenosine Monophosphate-activated protein kinase (AMPK) and non-AMPK pathways, amongst others, are deemed to explain the molecular mechanisms of action of metformin. Metformin is an established insulin receptor sensitising antihyperglycemic agent, is highly affordable, and has superior safety and efficacy profiles. Emerging experimental and clinical evidence suggests that metformin has pleiotropic non-glycemic effects. Metformin appears to have weight stabilising, renoprotective, neuroprotective, cardio-vascular protective, and antineoplastic effects and mitigates polycystic ovarian syndrome. Anti-inflammatory and antioxidant effects of metformin seem to qualify it as an adjunct therapy in treating infectious diseases such as tuberculosis, viral hepatitis, and the current novel Covid-19 infections. So far, metformin is the only prescription medicine relevant to the emerging field of senotherapeutics. Non-glycemic effects of metformin favourable to its repurposing in therapeutic use are hereby discussed.

Cytogenetic effects of antidiabetic drug metformin

Metformin (MET) is the first-choice antidiabetic drug for type 2 diabetes mellitus treatment. In this study, the genotoxic potential of MET was evaluated by using chromosome aberrations (CAs), sister chromatid exchanges (SCEs), and micronucleus (MN) assays in human peripheral lymphocytes as well as comet assay in isolated lymphocytes. Human lymphocytes were treated with different concentrations of MET (12.5, 25, 50, 75, 100, and 125 µg/mL) for 24 h and 48 h. A negative and a positive control (Mitomycin-C-MMC, 0.20 μg/mL, for CA, SCE, and MN tests; hydrogen peroxide-H₂O₂, 100 µM, for comet assay) were also maintained. MET significantly increased the frequency of CAs at 48 h exposure (except 12.5 µg/mL) compared to the negative control. MET increased SCEs/cells in both treatment periods (except 12.5 µg/mL at 24 h). MET only increased the frequency of MN at 125 µg/mL. While MET significantly increased the comet tail length (CTL) at four concentrations (25, 75, 100, and 125 µg/mL), it did not affect comet tail intensity (CTI) (except 125 µg/mL) and comet tail moment (CTM) at all the treatments. All these data showed that MET had a mild genotoxic effect, especially at a long treatment period and higher concentrations in human lymphocytes in vitro. However, further in vitro and especially in vivo studies should be conducted to understand the detailed genotoxic potential of MET.HighlightsMetformin increased the frequency of CAs and SCEs, especially at 48-h exposure time in human lymphocytes.This antidiabetic drug increased the frequency of MN only at the highest concentration tested (125 µg/mL).Metformin significantly increased the comet tail length in all treatments (except 50 µg/mL).The drug did not significantly affect the comet tail intensity (except 125 µg/mL) and comet tail moment in all treatments.

Cohort Study of Antihyperglycemic Medication and Pancreatic Cancer Patients Survival

Background: We assessed the association between the use of metformin and other antihyperglycemic medications on overall survival in diabetic patients with pancreatic cancer. Methods: Patients with pancreatic cancer and diabetes between 2000 and 2015 were identified from the Lithuanian Cancer Registry and the National Health Insurance Fund database. Cohort members were classified into six groups according to type 2 diabetes mellitus treatment: sulfonylurea monotherapy; metformin monotherapy; insulin monotherapy; metformin and sulfonylurea combination; metformin and other antihyperglycemic medications; all other combinations of oral antihyperglycemic medications. Survival was calculated from the date of cancer diagnosis to the date of death or the end of follow-up (31 December 2018). Results: Study group included 454 diabetic patients with pancreatic cancer. We found no statistically significant differences in overall survival between patients by glucose-lowering therapy. However, highest mortality risk was observed in patients on insulin monotherapy, and better survival was observed in the groups of patients using antihyperglycemic medication combinations, metformin alone, and metformin in combination with sulfonylurea. Analysis by cumulative dose of metformin showed significantly lower mortality risk in the highest cumulative dose category (HR 0.76, 95% CI 0.58–0.99). Conclusions: Our study showed that metformin might have a survival benefit for pancreatic cancer patients, suggesting a potentially available option for the treatment.

Islets and pancreatic ductal adenocarcinoma - An opportunity for translational research from the 'Bench to the Bedside'

The islet-acinar axis is of prime importance to the optimal functioning of the human pancreas. Not only is this inter-relationship important for normal physiological processes, it is also relevant in diseased states, including chronic pancreatitis and pancreatic ductal adenocarcinoma (PDAC). Early experiments, nearly 4 decades ago, explored the role of islets in the development and progression of PDAC. These led to further studies that provided compelling evidence to support the role of islets and their hormones in PDAC. This association presents oncologists with therapeutic options not only for managing, but potentially preventing PDAC, a cancer that is well known for its poor patient outcomes. This review will discuss the accumulated evidence regarding the role of islets and their hormones in PDAC and highlight areas for future research.

Potential therapies for residual hepatoblastoma following incomplete ablation treatment in a nude mouse subcutaneous xenograft model based on lncRNA and mRNA expression profiles

Tumor recurrence following radiofrequency ablation (RFA) treatment in liver cancer is an important factor affecting patient prognosis. Furthermore, the biological role of long non‑coding RNAs (lncRNAs) in residual hepatoblastoma (HB) tissues after RFA remains largely unknown. By using microarray technology, this study investigated the expression of lncRNAs and mRNAs among four pairs of HB tissues (incomplete ablation treatment and no treatment) in a nude mouse subcutaneous xenograft model. Subsequently, bioinformatics analysis was used to understand the functions and pathways of the identified mRNAs. Finally, a connectivity map (CMap) analysis was conducted to identify potential therapeutic strategies for residual HB tissues. Compared with the untreated nude mouse subcutaneous xenograft model, in the experimental group, a significant difference in the expression of 740 lncRNAs and 663 mRNAs was detected. Subsequently, bioinformatics analysis revealed that the differentially expressed mRNAs were significantly enriched in pathways associated with antigen processing, the presentation of endogenous antigens, the regulation of cellular metabolic processes, MAPK signaling and cell cycle regulation. Additionally, six compounds (valproic acid, metformin, tanespimycin, wortmannin, fulvestrant and MK‑886) were identified by CMap analysis as potential therapeutic agents for the treatment of residual HB tissues. These findings provide a novel insight into the pathogenesis of residual HB and potential therapeutic strategies for aggressive tumor recurrence following RFA treatment in patients with HB.

Cancer stem cells as therapeutic targets of pancreatic cancer

The discovery of stem cells and their potential abilities in self-renewal and differentiation has opened a new horizon in medicine. Scientists have found a small population of stem cells in some types of cancers with the same functions as normal stem cells. There are two models for tumor progression: clonal (stochastic) and cancer stem cell (CSCs) models. According to the first model, all transformed cells in the tumor have carcinogenic potential and are able to proliferate and produce the same cells. The latter model, which has received more attention recently, considers the role of CSCs in drug resistance and tumor metastasis. Following the model, researchers have found that targeting CSCs may be a promising way in cancer therapy. This review describes CSC characteristics in general, while also focusing on CSC properties in the context of pancreatic cancer.

Meta-Analysis of Microarray Expression Studies on Metformin in Cancer Cell Lines

Several studies have demonstrated that metformin (MTF) acts with variable efficiency as an anticancer agent. The pleiotropic anticancer effects of MTF on cancer cells have not been fully explored yet. By interrogating the Gene Expression Omnibus (GEO) for microarray expression data, we identified eight eligible submissions, representing five different studies, that employed various conditions including different cell lines, MTF concentrations, treatment durations, and cellular components. A compilation of the data sets of 13 different conditions contained 443 repeatedly up- and 387 repeatedly down-regulated genes; the majority of these 830 differentially expressed genes (DEGs) were associated with higher MTF concentrations and longer MTF treatment. The most frequently upregulated genes include DNA damage inducible transcript 4 (DDIT4), chromodomain helicase DNA binding protein 2 (CHD2), endoplasmic reticulum to nucleus signaling 1 (ERN1), and growth differentiation factor 15 (GDF15). The most commonly downregulated genes include arrestin domain containing 4 (ARRDC4), and thioredoxin interacting protein (TXNIP). The most significantly (p-value < 0.05, Fisher’s exact test) overrepresented protein class was entitled, nucleic acid binding. Cholesterol biosynthesis and other metabolic pathways were specifically affected by downregulated pathway molecules. In addition, cell cycle pathways were significantly related to the data set. Generated networks were significantly related to, e.g., carbohydrate and lipid metabolism, cancer, cell cycle, and DNA replication, recombination, and repair. A second compilation comprised genes that were at least under one condition up- and in at least another condition down-regulated. Herein, the most frequently deregulated genes include nuclear paraspeckle assembly transcript 1 (NEAT1) and insulin induced gene 1 (INSIG1). The most significantly overrepresented protein classes in this compilation were entitled, nucleic acid binding, ubiquitin-protein ligase, and mRNA processing factor. In conclusion, this study provides a comprehensive list of deregulated genes and biofunctions related to in vitro MTF application and individual responses to different conditions. Biofunctions affected by MTF include, e.g., cholesterol synthesis and other metabolic pathways, cell cycle, and DNA replication, recombination, and repair. These findings can assist in defining the conditions in which MTF exerts additive or synergistic effects in cancer treatment.

Heme Oxygenase-1 Inhibition Sensitizes Human Prostate Cancer Cells towards Glucose Deprivation and Metformin-Mediated Cell Death

High levels of heme oxygenase (HO)-1 have been frequently reported in different human cancers, playing a major role in drug resistance and regulation of cancer cell redox homeostasis. Metformin (MET), a drug widely used for type 2 diabetes, has recently gained interest for treating several cancers. Recent studies indicated that the anti-proliferative effects of metformin in cancer cells are highly dependent on glucose concentration. The present work was directed to determine whether use of a specific inhibitor of HO-1 activity, alone or in combination with metformin, affected metastatic prostate cancer cell viability under different concentrations of glucose. MTT assay and the xCELLigence system were used to evaluate cell viability and cell proliferation in DU145 human prostate cancer cells. Cell apoptosis and reactive oxygen species were analyzed by flow cytometry. The activity of HO-1 was inhibited using a selective imidazole-based inhibitor; genes associated with antioxidant systems and cell death were evaluated by qRT-PCR. Our study demonstrates that metformin suppressed prostate cancer growth in vitro and increased oxidative stress. Disrupting the antioxidant HO-1 activity, especially under low glucose concentration, could be an attractive approach to potentiate metformin antineoplastic effects and could provide a biochemical basis for developing HO-1-targeting drugs against solid tumors.

Cyclopamine tartrate, a modulator of hedgehog signaling and mitochondrial respiration, effectively arrests lung tumor growth and progression

Lung cancer remains the leading cause of cancer-related death, despite the advent of targeted therapies and immunotherapies. Therefore, it is crucial to identify novel molecular features unique to lung tumors. Here, we show that cyclopamine tartrate (CycT) strongly suppresses the growth of subcutaneously implanted non-small cell lung cancer (NSCLC) xenografts and nearly eradicated orthotopically implanted NSCLC xenografts. CycT reduces heme synthesis and degradation in NSCLC cells and suppresses oxygen consumption in purified mitochondria. In orthotopic tumors, CycT decreases the levels of proteins and enzymes crucial for heme synthesis, uptake, and oxidative phosphorylation (OXPHOS). CycT also decreases the levels of two regulators promoting OXPHOS, MYC and MCL1, and effectively alleviates tumor hypoxia. Evidently, CycT acts via multiple modes to suppress OXPHOS. One mode is to directly inhibit mitochondrial respiration/OXPHOS. Another mode is to inhibit heme synthesis and degradation. Both modes appear to be independent of hedgehog signaling. Addition of heme to NSCLC cells partially reverses the effect of CycT on oxygen consumption, proliferation, and tumorigenic functions. Together, our results strongly suggest that CycT suppress tumor growth in the lung by inhibiting heme metabolism and OXPHOS. Targeting heme metabolism and OXPHOS may be an effective strategy to combat lung cancer.

Obesity-induced pancreatopathy in rats is reversible after bariatric surgery

Obesity is a risk factor for pancreatic diseases. Bariatric surgery is one of the most efficient treatments of morbid obesity. The aims were to assess pancreatic endocrine and exocrine lesions in obese rats, to analyze effects of bariatric surgery. Sixty-three male Wistar rats were included in five groups: 2 fed with high fat diet (HFD) or normal diet for 3 months, 2 fed with HFD or normal diet for 6 months; 1 group fed with HFD and undergoing bariatric surgery (n = 30). Quantitative MR imaging was performed in HFD₆, ND₆ and HFD₃-BS. Pancreas specimens were analyzed after sacrifice for adipocyte infiltration, fibrosis, acinar-ductal metaplasia, abnormality of Langerhans islets (HHF: hypertrophy, hypervascularisation, fibrosis), and hemosiderin deposits in acinar or endocrine locations. We found that HFD₆ rats had more fibro-inflammatory islets (P = 0.0139) and acinar-ducal metaplasia (P = 0.0843) than HFD₃ rats. Rats with HFD₃₊₆ had more fibro-inflammatory islets (P < 0.0001), hemosiderin deposits (p < 0.0001), fat infiltration (P = 0.0008) and acinar-ductal metaplasia lesions (P = 0.0424). Weight increase was associated with glycoregulation abnormalities (r = 0.44, P = 0.08) and adipocyte infiltrations (P = 0.009). After surgery, less fibro-inflammatory islets (P = 0.0004), fat and iron infiltrates (P = 0.005 and P = 0.06), and acino-ductal metaplasia (P = 0.05) were observed compared to HFD₆ rats. MR image quantifications revealed increased elasticity, fat fraction, and R2 and a decreased elasticity wave dispersion coefficient in the high fat groups that reversed after surgery. MRI parameters were in strong correlation with respective histological counterparts. In conclusion, obese rats develop pancreatic inflammatory lesions with acinar-ductal metaplasia in acinar location and the endocrine-exocrine interface. These changes can be prevented by bariatric surgery. Quantitative MR imaging is accurate in identifying early pancreatic lesions.

Essential roles of mitochondrial and heme function in lung cancer bioenergetics and tumorigenesis

Contrary to Warburg’s hypothesis, mitochondrial oxidative phosphorylation (OXPHOS) contributes significantly to fueling cancer cells. Several recent studies have demonstrated that radiotherapy-resistant and chemotherapy-resistant cancer cells depend on OXPHOS for survival and progression. Several cancers exhibit an increased risk in association with heme intake. Mitochondria are widely known to carry out oxidative phosphorylation. In addition, mitochondria are also involved in heme synthesis. Heme serves as a prosthetic group for several proteins that constitute the complexes of mitochondrial electron transport chain. Therefore, heme plays a pivotal role in OXPHOS and oxygen consumption. Further, lung cancer cells exhibit heme accumulation and require heme for proliferation and invasion in vitro. Abnormalities in mitochondrial biogenesis and mutations are implicated in cancer. This review delves into mitochondrial OXPHOS and lesser explored area of heme metabolism in lung cancer.

Pleiotropic Effects of Metformin on Cancer

Metformin (MTF) is a natural compound derived from the legume Galega officinalis. It is the first line antidiabetic drug for type 2 diabetes (T2D) treatment. One of its main antidiabetic effects results from the reduction of hepatic glucose release. First scientific evidence for the anticancer effects of MTF was found in animal research, published in 2001, and some years later a retrospective observational study provided evidence that linked MTF to reduced cancer risk in T2D patients. Its pleiotropic anticancer effects were studied in numerous in vitro and in vivo studies at the molecular and cellular level. Although the majority of these studies demonstrated that MTF is associated with certain anticancer properties, clinical studies and trials provided a mixed view on its beneficial anticancer effects. This review emphasizes the pleiotropic effects of MTF and recent progress made in MTF applications in basic, preclinical, and clinical cancer research.

Effect of different glucose-lowering therapies on cancer incidence in type 2 diabetes: An observational population-based study

AIM

To assess the effect of metformin on cancer incidence in type 2 diabetes (T2DM), considering possible interactions with other glucose-lowering drugs and diabetes duration.

METHODS

Study cohort included diabetes patients aged 20-84 on December 2009, still alive and resident in Reggio Emilia province as of December 2011. Drug exposure was assessed for 2009-2011; subjects taking metformin continuously, with or without other hypoglycaemic drugs, were compared to subjects on diet-only therapy. The cohort was followed up from 2012 to 2014 through the cancer registry. Age- and sex-adjusted incidence rate ratios (IRRs) were computed using Poisson regression models for all sites, lung, breast, liver, colorectal, prostate and pancreatic cancer.

RESULTS

The cohort includes 17,026 people with T2DM, 7460 taking metformin. 887 cancers occurred during follow-up, 348 among metformin users. Cancer risk was similar in T2DM patients using metformin and those on diet-only. The risk for prostate (IRR = 0.65; 95%CI:0.36; 1.17), liver (IRR = 0.82; 95%CI:0.36; 1.85) and breast (IRR = 0.77; 95%CI:0.43; 1.40) cancers only was slightly reduced; for lung (IRR = 1.52; 95%CI:0.92; 2.50), pancreas (IRR = 1.51; 95%CI:0.59:3.89) and colon-rectum (IRR = 1.71; 95%CI:0.94; 3.08) the risk was slightly increased.

CONCLUSIONS

There is no evidence of antitumor effect of metformin. A possible decrease only for breast, liver and prostate cancer, is compatible with random fluctuations.

Advances in Pancreatic Cancer, Intraductal Papillary Mucinous Neoplasms, and Pancreatitis

According to the theme of the Golden Jubilee Issue of our journal, we present a commentary on landmark contributions reported in the journal on pancreatic cancer, pancreatic cysts, and intraductal papillary mucinous neoplasms (IPMN) and pancreatitis.

Evidence-based complementary treatment of pancreatic cancer: a review of adjunct therapies including paricalcitol, hydroxychloroquine, intravenous vitamin C, statins, metformin, curcumin, and aspirin

Despite new and exciting research and renewed optimism about future therapy, current statistics of survival from pancreatic cancer remains dismal. Patients seeking alternative or complementary treatments should be warned to avoid the hype and instead look to real science. A variety of relatively safe and inexpensive treatment options that have shown success in preclinical models and/or retrospective studies are currently available. Patients require their physicians to provide therapeutic guidance and assistance in obtaining and administrating these various therapies. Paricalcitol, an analog of vitamin D, has been shown by researchers at the Salk Institute for Biological Studies to break though the protective stroma surrounding tumor cells. Hydroxychloroquine has been shown to inhibit autophagy, a process by which dying cells recycle injured organelles and internal toxins to generate needed energy for survival and reproduction. Intravenous vitamin C creates a toxic accumulation of hydrogen peroxide within cancer cells, hastening their death. Metformin inhibits mitochondrial oxidative metabolism utilized by cancer stem cells. Statins inhibit not only cholesterol but also other factors in the same pathway that affect cancer cell growth, protein synthesis, and cell cycle progression. A novel formulation of curcumin may prevent resistance to chemotherapy and inhibit pancreatic cancer cell proliferation. Aspirin therapy has been shown to prevent pancreatic cancer and may be useful to prevent recurrence. These therapies are all currently available and are reviewed in this paper with emphasis on the most recent laboratory research and clinical studies.

Metformin Decreases the Incidence of Pancreatic Ductal Adenocarcinoma Promoted by Diet-induced Obesity in the Conditional KrasG12D Mouse Model

Pancreatic ductal adenocarcinoma (PDAC) is a particularly deadly disease. Chronic conditions, including obesity and type-2 diabetes are risk factors, thus making PDAC amenable to preventive strategies. We aimed to characterize the chemo-preventive effects of metformin, a widely used anti-diabetic drug, on PDAC development using the Kras^G12D mouse model subjected to a diet high in fats and calories (HFCD). LSL-Kras^G12D/+;p48-Cre (KC) mice were given control diet (CD), HFCD, or HFCD with 5 mg/ml metformin in drinking water for 3 or 9 months. After 3 months, metformin prevented HFCD-induced weight gain, hepatic steatosis, depletion of intact acini, formation of advanced PanIN lesions, and stimulation of ERK and mTORC1 in pancreas. In addition to reversing hepatic and pancreatic histopathology, metformin normalized HFCD-induced hyperinsulinemia and hyperleptinemia among the 9-month cohort. Importantly, the HFCD-increased PDAC incidence was completely abrogated by metformin (p < 0.01). The obesogenic diet also induced a marked increase in the expression of TAZ in pancreas, an effect abrogated by metformin. In conclusion, administration of metformin improved the metabolic profile and eliminated the promoting effects of diet-induced obesity on PDAC formation in KC mice. Given the established safety profile of metformin, our findings have a strong translational potential for novel chemo-preventive strategies for PDAC.

Obesity-Related Digestive Diseases and Their Pathophysiology

Obesity is a growing medical and public health problem worldwide. Many digestive diseases are related to obesity. In this article, the current state of our knowledge of obesity-related digestive diseases, their pathogenesis, and the medical and metabolic consequences of weight reduction are discussed. Obesity-related digestive diseases include gastroesophageal reflux disease, Barrett’s esophagus, esophageal cancer, colon polyp and cancer, nonalcoholic fatty liver disease, hepatitis C-related disease, hepatocellular carcinoma, gallstone, cholangiocarcinoma, and pancreatic cancer. Although obesity-related esophageal diseases are associated with altered mechanical and humoral factors, other obesity-related digestive diseases seem to be associated with obesity-induced altered circulating levels of adipocytokines and insulin resistance. The relationship between functional gastrointestinal disease and obesity has been debated. This review provides a comprehensive evaluation of the obesity-related digestive diseases, including pathophysiology, obesity-related risk, and medical and metabolic effects of weight reduction in obese subjects.

The expanding role of metformin in cancer: an update on antitumor mechanisms and clinical development

Metformin has been used for nearly a century to treat type 2 diabetes mellitus. Epidemiologic studies first identified the association between metformin and reduced risk of several cancers. The anticancer mechanisms of metformin involve both indirect or insulin-dependent pathways and direct or insulin-independent pathways. Preclinical studies have demonstrated metformin's broad anticancer activity across a spectrum of malignancies. Prospective clinical trials involving metformin in the chemoprevention and treatment of cancer now number in the hundreds. We provide an update on the anticancer mechanisms of metformin and review the results thus far available from prospective clinical trials investigating metformin's efficacy in cancer.

Increased efficacy of metformin corresponds to differential metabolic effects in the ovarian tumors from obese versus lean mice

Obesity is a significant risk factor for ovarian cancer (OC) and associated with worse outcomes for this disease. We assessed the anti-tumorigenic effects of metformin in human OC cell lines and a genetically engineered mouse model of high grade serous OC under obese and lean conditions. Metformin potently inhibited growth in a dose-dependent manner in all four human OC cell lines through AMPK/mTOR pathways. Treatment with metformin resulted in G1 arrest, induction of apoptosis, reduction of invasion and decreased hTERT expression. In the K18-gT₁₂₁^+/-; p53^fl/fl; Brca1^fl/fl (KpB) mouse model, metformin inhibited tumor growth in both lean and obese mice. However, in the obese mice, metformin decreased tumor growth by 60%, whereas tumor growth was only decreased by 32% in the lean mice (p=0.003) compared to vehicle-treated mice. The ovarian tumors from obese mice had evidence of impaired mitochondrial complex 2 function and energy supplied by omega fatty acid oxidation rather than glycolysis as compared to lean mice, as assessed by metabolomic profiling. The improved efficacy of metformin in obesity corresponded with inhibition of mitochondrial complex 1 and fatty acid oxidation, and stimulation of glycolysis in only the OCs of obese versus lean mice. In conclusion, metformin had anti-tumorigenic effects in OC cell lines and the KpB OC pre-clinical mouse model, with increased efficacy in obese versus lean mice. Detected metabolic changes may underlie why ovarian tumors in obese mice have heightened susceptibility to metformin.

Metformin: a review of its potential indications

Metformin is the most commonly prescribed drug for type 2 diabetes mellitus. In recent years, in addition to glucose lowering, several studies have presented evidence suggesting some potential role for metformin, such as antitumor effect, antiaging effect, cardiovascular protective effect, neuroprotective effect or an optional treatment for polycystic ovary syndrome. This paper will critically review the role of metformin to provide reference for doctors and researchers.

Survival benefits in colorectal adenocarcinoma with the use of metformin among a black diabetic inner city population

We assessed the association of metformin use with survival in colorectal cancer in a population consists mostly of African-American and Afro-Caribbean patients. We identified 585 colorectal cancer patients, 167 (28.6%) and 418 (71.5%) were as diabetic (DM) and nondiabetic, respectively. The diagnosis of diabetes did not impact cancer survival or extent of disease. Overall, DMs with metformin use (D+M+) have better overall survival than both DMs without metformin use (D+M∼) and nondiabetics (D∼M∼), with a mean survival of 109.9 months compared with 95.7 and 106.1 months, respectively (log-rank p < 0.05). The use of metformin shows significant reduction of risk of mortality compared with nonusers (hazard ratio: 0.34; 95% CI: 0.15-0.81; p = 0.01). Use of insulin and status of diabetes did not have a significant impact on overall cancer survival.

ROS Production and ERK Activity Are Involved in the Effects of d-β-Hydroxybutyrate and Metformin in a Glucose Deficient Condition

Hypoglycemia, a complication of insulin or sulfonylurea therapy in diabetic patients, leads to brain damage. Furthermore, glucose replenishment following hypoglycemic coma induces neuronal cell death. In this study, we investigated the molecular mechanism underlying glucose deficiency-induced cytotoxicity and the protective effect of d-β-hydroxybutyrate (D-BHB) using SH-SY5Y cells. The cytotoxic mechanism of metformin under glucose deficiency was also examined. Cell viability under 1 mM glucose (glucose deficiency) was significantly decreased which was accompanied by increased production of reactive oxygen species (ROS) and decreased phosphorylation of extracellular signal-regulated kinase (ERK) and glycogen synthase 3 (GSK3β). ROS inhibitor reversed the glucose deficiency-induced cytotoxicity and restored the reduced phosphorylation of ERK and GSK3β. While metformin did not alter cell viability in normal glucose media, it further increased cell death and ROS production under glucose deficiency. However, D-BHB reversed cytotoxicity, ROS production, and the decrease in phosphorylation of ERK and GSK3β induced by the glucose deficiency. ERK inhibitor reversed the D-BHB-induced increase in cell viability under glucose deficiency, whereas GSK3β inhibitor did not restore glucose deficiency-induced cytotoxicity. Finally, the protective effect of D-BHB against glucose deficiency was confirmed in primary neuronal cells. We demonstrate that glucose deficiency-induced cytotoxicity is mediated by ERK inhibition through ROS production, which is attenuated by D-BHB and intensified by metformin.

Metformin inhibits estrogen-dependent endometrial cancer cell growth by activating the AMPK-FOXO1 signal pathway

Metformin is an oral biguanide commonly used for treating type II diabetes and has recently been reported to possess antiproliferative properties that can be exploited for the prevention and treatment of a variety of cancers. The mechanisms underlying this effect have not been fully elucidated. Our study shows a marked loss of AMP-activated protein kinase (AMPK) phosphorylation and nuclear human Forkhead box O1 (FOXO1) protein in estrogen-dependent endometrial cancer (EC) tumors compared to normal control endometrium. Metformin treatment suppressed EC cell growth in a time-dependent manner in vitro; this effect was cancelled by cotreatment with an AMPK inhibitor, compound C. Metformin decreased FOXO1 phosphorylation and increased FOXO1 nuclear localization in Ishikawa and HEC-1B cells, with non-significant increase in FOXO1 mRNA expression. Moreover, compound C blocked the metformin-induced changes of FOXO1 and its phosphorylation protein, suggesting that metformin upregulated FOXO1 activity by AMPK activation. Similar results were obtained after treatment with insulin. In addition, transfection with siRNA for FOXO1 cancelled metformin-inhibited cell growth, indicating that FOXO1 mediated metformin to inhibit EC cell proliferation. A xenograft mouse model further revealed that metformin suppressed HEC-1B tumor growth, accompanied by downregulated ki-67 and upregulated AMPK phosphorylation and nuclear FOXO1 protein. Taken together, these data provide a novel mechanism of antineoplastic effect for metformin through the regulation of FOXO1, and suggest that the AMPK-FOXO1 pathway may be a therapeutic target to the development of new antineoplastic drugs.

PPAR Gamma in Neuroblastoma: The Translational Perspectives of Hypoglycemic Drugs

Neuroblastoma (NB) is the most common and aggressive pediatric cancer, characterized by a remarkable phenotypic diversity and high malignancy. The heterogeneous clinical behavior, ranging from spontaneous remission to fatal metastatic disease, is attributable to NB biology and genetics. Despite major advances in therapies, NB is still associated with a high morbidity and mortality. Thus, novel diagnostic, prognostic, and therapeutic approaches are required, mainly to improve treatment outcomes of high-risk NB patients. Among neuroepithelial cancers, NB is the most studied tumor as far as PPAR ligands are concerned. PPAR ligands are endowed with antitumoral effects, mainly acting on cancer stem cells, and constitute a possible add-on therapy to antiblastic drugs, in particular for NB with unfavourable prognosis. While discussing clinical background, this review will provide a synopsis of the major studies about PPAR expression in NB, focusing on the potential beneficial effects of hypoglycemic drugs, thiazolidinediones and metformin, to reduce the occurrence of relapses as well as tumor regrowth in NB patients.

Impaired glucose tolerance and metformin: clinical and mechanistic aspects

The Diabetes Prevention Program (DPP) showed that metformin reduced the incidence of diabetes in subjects with impaired glucose tolerance (IGT) who were at high risk of progression to type 2 diabetes. Metformin was not as efficient as intensive life style intervention, but had a clinically significant effect in obese individuals and in those with impaired fasting glucose (IFG). This review discusses the clinical implications and the mechanistic aspects of the effect of metformin in IGT and IFG. Acute actions of metformin on postprandial metabolism to improve hepatic glucose handling and improve the lipid profile could contribute to the lower incidence of diabetes. Longer term improvements in haemodynamic parameters and reduced oxidative stress are also implicated. Metformin offers a potential alternative or complement to lifestyle intervention for IGT, and deserves further evaluation in this respect.

Serendipity in Cancer Drug Discovery: Rational or Coincidence?

Novel drug development leading to final approval by the US FDA can cost as much as two billion dollars. Why the cost of novel drug discovery is so expensive is unclear, but high failure rates at the preclinical and clinical stages are major reasons. Although therapies targeting a given cell signaling pathway or a protein have become prominent in drug discovery, such treatments have done little in preventing or treating any disease alone because most chronic diseases have been found to be multigenic. A review of the discovery of numerous drugs currently being used for various diseases including cancer, diabetes, cardiovascular, pulmonary, and autoimmune diseases indicates that serendipity has played a major role in the discovery. In this review we provide evidence that rational drug discovery and targeted therapies have minimal roles in drug discovery, and that serendipity and coincidence have played and continue to play major roles. The primary focus in this review is on cancer-related drug discovery.

Metformin Protects Against Cisplatin-Induced Tubular Cell Apoptosis and Acute Kidney Injury via AMPKα-regulated Autophagy Induction

Metformin, one of the most common prescriptions for patients with type 2 diabetes, is reported to protect the kidney from gentamicin-induced nephrotoxicity. However, the role and mechanisms for metformin in preventing cisplatin-induced nephrotoxicity remains largely unknown. In this study, a single intraperitoneal injection of cisplatin was employed to induce acute kidney injury (AKI) in CD1 mice. The mice exhibited severe kidney dysfunction and histological damage at day 2 after cisplatin injection. Pretreatment of metformin could markedly attenuate cisplatin-induced acute kidney injury, tubular cell apoptosis and inflammatory cell accumulation in the kidneys. Additionally, pretreatment of metformin could enhance both AMPKα phosphorylation and autophagy induction in the kidneys after cisplatin injection. In cultured NRK-52E cells, a rat kidney tubular cell line, metformin could stimulate AMPKα phosphorylation, induce autophagy and inhibit cisplatin-induced cell apoptosis. Blockade of either AMPKα activation or autophagy induction could largely abolish the protective effect of metformin in cisplatin-induced cell death. Together, this study demonstrated that metformin may protect against cisplatin-induced tubular cell apoptosis and AKI through stimulating AMPKα activation and autophagy induction in the tubular cells.

Metformin Restrains Pancreatic Duodenal Homeobox-1 (PDX-1) Function by Inhibiting ERK Signaling in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most potent and perilous diseases known, with a median survival rate of 3-5 months due to the combination of only advanced stage diagnosis and ineffective therapeutic options. Metformin (1,1-Dimethylbiguanide hydrochloride), the leading drug used for type 2 diabetes mellitus, emerges as a potential therapy for PDAC and other human cancers. Metformin exerts its anticancer action via a variety of adenosine monophosphate (AMP)-activated protein kinase (AMPK)- dependent and/or AMPK-independent mechanisms. We present data here showing that metformin downregulated pancreatic transcription factor pancreatic duodenal homeobox-1 (PDX-1), suggesting a potential novel mechanism by which metformin exerts its anticancer action. Metformin inhibited PDX-1 expression at both protein and mRNA levels and PDX-1 transactivity as well in PDAC cells. Extracellular signal-regulated kinase (ERK) was identified as a PDX-1-interacting protein by antibody array screening in GFP-PDX-1 stable HEK293 cells. Co-transfection of ERK1 with PDX-1 resulted in an enhanced PDX-1 expression in HEK293 cells in a dose-dependent manner. Immunoprecipitation/Western blotting analysis confirmed the ERK-PDX-1 interaction in PANC-1 cells stimulated by epidermal growth factor (EGF). EGF induced an enhanced PDX-1 expression in PANC-1 cells and this stimulation was inhibited by MEK inhibitor PD0325901. Metformin inhibited EGF-stimulated PDX-1 expression with an accompanied inhibition of ERK kinase activation in PANC- 1 cells. Taken together, our studies show that PDX-1 is a potential novel target for metformin in PDAC cells and that metformin may exert its anticancer action in PDAC by down-regulating PDX-1 via a mechanism involving inhibition of ERK signaling.

Metformin for cancer and aging prevention: is it a time to make the long story short?

During the last decade, the burst of interest is observed to antidiabetic biguanide metformin as candidate drug for cancer chemoprevention. The analysis of the available data have shown that the efficacy of cancer preventive effect of metformin (MF) and another biguanides, buformin (BF) and phenformin (PF), has been studied in relation to total tumor incidence and to 17 target organs, in 21 various strains of mice, 4 strains of rats and 1 strain of hamsters (inbred, outbred, transgenic, mutant), spontaneous (non- exposed to any carcinogenic agent) or induced by 16 chemical carcinogens of different classes (polycycIic aromatic hydrocarbons, nitroso compounds, estrogen, etc.), direct or indirect (need metabolic transformation into proximal carcinogen), by total body X-rays and γ- irradiation, viruses, genetic modifications or special high fat diet, using one stage and two-stage protocols of carcinogenesis, 5 routes of the administration of antidiabetic biguanides (oral gavage, intraperitoneal or subcutaneous injections, with drinking water or with diet) in a wide ranks of doses and treatment regimens. In the majority of cases (86%) the treatment with biguanides leads to inhibition of carcinogenesis. In 14% of the cases inhibitory effect of the drugs was not observed. Very important that there was no any case of stimulation of carcinogenesis by antidiabetic biguanides. It was conclude that there is sufficient experimental evidence of anti-carcinogenic effect of antidiabetic biguanides.

(Ir)relevance of Metformin Treatment in Patients with Metastatic Pancreatic Cancer: An Open-Label, Randomized Phase II Trial

PURPOSE

We aimed to assess the safety and efficacy of metformin for treating patients with metastatic pancreatic cancer and to identify endocrine and metabolic phenotypic features or tumor molecular markers associated with sensitivity to metformin antineoplastic action.

EXPERIMENTAL DESIGN

We designed an open-label, randomized, phase II trial to assess the efficacy of adding metformin to a standard systemic therapy with cisplatin, epirubicin, capecitabine, and gemcitabine (PEXG) in patients with metastatic pancreatic cancer. Patients ages 18 years or older with metastatic pancreatic cancer were randomly assigned (1:1) to receive PEXG every 4 weeks in combination or not with 2 g oral metformin daily. The primary endpoint was 6-months progression-free survival (PFS-6) in the intention-to-treat population.

RESULTS

Between August 2010 and January 2014, we randomly assigned 60 patients to receive PEXG with (n = 31) or without metformin (n = 29). At the preplanned interim analysis, the study was ended for futility. PFS-6 was 52% [95% confidence interval (CI), 33-69] in the control group and 42% (95% CI, 24-59) in the metformin group (P = 0.61). Furthermore, there was no difference in disease-free survival and overall survival between groups. Despite endocrine metabolic modifications induced by metformin, there was no correlation with the outcome. Single-nucleotide polymorphism rs11212617 predicted glycemic response, but not tumor response to metformin. Gene expression on tumor tissue did not predict tumor response to metformin.

CONCLUSIONS

Addition of metformin at the dose commonly used in diabetes did not improve outcome in patients with metastatic pancreatic cancer treated with standard systemic therapy. See related commentary by Yang and Rustgi, p. 1031.

Metformin impairs Rho GTPase signaling to induce apoptosis in neuroblastoma cells and inhibits growth of tumors in the xenograft mouse model of neuroblastoma

Metformin has been shown to inhibit tumor growth in xenograft rodent models of adult cancers, and various human clinical trials are in progress. However, the precise molecular mechanisms of metformin action are largely unknown. In the present study we examined the anti-tumor activity of metformin against neuroblastoma, and determined the underlying signaling mechanisms. Using human neuroblastoma xenograft mice, we demonstrated that oral administration of metformin (100 and 250 mg/kg body weight) significantly inhibited the growth of tumors. The interference of metformin in spheroid formation further confirmed the anti-tumor activity of metformin. In tumors, the activation of Rac1 (GTP-Rac1) and Cdc42 (GTP-Cdc42) was increased while RhoA activation (GTP-RhoA) was decreased by metformin. It also induced phosphorylation of JNK and inhibited the phosphorylation of ERK1/2 without affecting p38 MAP Kinase. Infection of cells by adenoviruses expressing dominant negative Rac1 (Rac1-N17), Cdc42 (Cdc42-N17) or constitutively active RhoA (RhoA-V14), or incubation of cells with pharmacological inhibitors of Rac1 (NSC23766) or Cdc42 (ML141) significantly protected neuroblastoma cells from metformin-induced apoptosis. Additionally, inhibition of JNK activity along with Rac1 or Cdc42 attenuated cytotoxic effects of metformin. These studies demonstrated that metformin impairs Rho GTPases signaling to induce apoptosis via JNK pathway.

Repurposing old drugs to chemoprevention: the case of metformin

Multiple epidemiologic studies have documented an association between the anti-diabetic agent metformin and reduced cancer incidence and mortality. However, this effect has not been consistently demonstrated in animal models or more recent epidemiological studies. The purpose of this paper is to examine metformin's chemopreventive potential by reviewing relevant mechanisms of action, preclinical evidence of efficacy, updated epidemiologic evidence after correction for potential biases and confounders, and recently completed and ongoing clinical trials. Although repurposing drugs with well described mechanisms of action and safety profiles is an appealing strategy for cancer prevention, there is no substitute for well executed late phase clinical trials to define efficacy and populations that are most likely to benefit from an intervention.