Metformin use improves survival of diabetic liver cancer patients: systematic review and meta-analysis

Dataset for analysis of metabolic pathways and their reversibility associated with anti-proliferative effect of metformin in liver cancer cells

Despite epidemiological indications, utility of metformin in liver cancer remains debated and the understanding of the mechanism underlying its anti-cancer effects remains incomplete. Particularly, whether it operates via similar mechanism under glucose-sufficient and glucose- deficient environments or whether these effects are reversible remains unexplored. This metabolomic dataset was collected from liver cancer (HepG2) cells treated with metformin or placebo over a period of 3 h to 48 h as well as from cells recovering after metformin withdrawal. Cells were exposed to placebo or 2.5 mM metformin with or without glucose (5 mM) supplementation. The cells were harvested at 3, 6, 12, 24, and 48 h post-treatment. Cells were also harvested after 24 h of treatment under one of these conditions followed by reversal of glucose and/or metformin exposure status for 48 h. Metabolites from six biological replicates of each experimental group were extracted using chilled monophasic metabolite extraction solvent (Water: Acetonitrile: Isopropanol= 2:3:3) containing homovanillic acid as an internal standard. Samples were derivatized using MOX reagent followed by MSTFA. Untargeted metabolomic profiling of derivatized samples were performed using an Agilent 7890B gas chromatograph coupled to a 5977B single quadrupole mass spectrometer. Analytes were injected through a splitless liner and separated on a HP-5MS ultra-inert column using ultrapure helium as the carrier gas. Peak alignment, annotation, and integration were done using Agilent MassHunter Quantitative analysis software. Multivariate analysis was performed using MetaboAnalyst 5.0. These experiments were performed to unravel the longitudinal evolution of cellular metabolome in response to metformin treatment, its glucose dependence, as well as to examine the reversibility of these changes. The dataset can help to identify glucose-independent pathways involved in anti-cancer effect of metformin. The dataset can be used to design experiments to develop novel therapeutic combinations synergistically acting with metformin to cripple the metabolic fitness of cancer cells. It can also help to develop experiments to test the effect of metformin withdrawal in liver cancer.

The effectiveness of brief reminiscence-based psychosocial interventions for cancer patients: A systematic review and meta-analysis

AIM

To determine the effectiveness of brief reminiscence-based psychosocial interventions in alleviating psychological distress in cancer patients.

BACKGROUND

Cancer patients suffer tremendous psycho-spiritual pain, which affects their quality of life. Brief reminiscence-based psychosocial interventions have demonstrated positive effects on the mental health of cancer patients; however, the efficacy of these interventions has been inconsistent.

DESIGN

A systematic review and meta-analysis.

METHODS

This review was conducted and reported in accordance with the PRISMA 2020 checklist provided by the EQUATOR network. The Cochrane Library, Web of Science, PsycINFO, PubMed, Embase, CINAHL and Scopus databases were systematically searched from inception to 27 November 2022 to identify randomised controlled trials (RCTs) published in English.

RESULTS

Twenty studies involving 1744 cancer participants were included. The meta-analysis showed statistically significant effects of brief reminiscence-based psychosocial interventions on hope, anxiety and depression at post-intervention. A separate analysis revealed that brief reminiscence-based psychosocial interventions had a sustainable effect on hope, spiritual well-being, anxiety and depression at 1 month after the intervention. However, no statistically significant effect on quality of life was found in our study either immediately after the intervention or at 1 month.

CONCLUSIONS

Brief reminiscence-based psychosocial interventions can significantly reduce anxiety and depressive symptoms and improve hope and spiritual well-being in cancer patients.

RELEVANCE TO CLINICAL PRACTICE

This study further supports that brief reminiscence-based psychosocial interventions should be incorporated into the routine care of cancer patients to address their psychosocial distress.

PATIENT OR PUBLIC CONTRIBUTION

All authors of this article contributed to the study conception and design. All authors of the included studies provided original data for this paper.

Effect of Metformin Use on Survival and Recurrence Rate of Gastric Cancer After Gastrectomy in Diabetic Patients: A Systematic Review and Meta-analysis of Observational Studies

BACKGROUND

Gastric cancer (GC) is one of the most common worldwide cancers and causes of death. Various studies have investigated the effect of metformin on overall survival (OS), cancer-specific survival (CSS), recurrence-free survival (RFS), and recurrence rate in diabetic patients after gastrectomy, and their results have been contradictory. This meta-analysis aimed to evaluate the effect of metformin use compared to sulfonylurea compounds with OS, CSS, RFS, and recurrence rate after gastrectomy in diabetic patients.

METHODS

We reviewed the Scopus, Google Scholar, PubMed, Web of Science, and Embassy databases until September 2022 based on appropriate MESH terms. All observational studies that evaluated the effect of metformin on survival in diabetic patients who underwent surgery for GC were included. The hazard ratio (HR) with a 95% confidence interval was used to estimate the effect size. The Egger test was used to evaluate publication bias.

RESULTS

Overall, nine studies, including 245,387 GC patients who underwent surgery, were included. The use of metformin significantly increased the OS rate (HR: 0.81, 95% CI: 0.78, 0.86, P: 0.001, I2: 4.5%), CSS rate (HR: 0.72, 95% CI: 0.63, 0.81, P: 0.011, I2 = 0%), and RFS rate (HR: 719, 95% CI: 0.524, 0.986, P: 0.001) and decreased the recurrence rate after gastrectomy (HR: 0.83, 95% CI: 0.77, 0.87, P: 0.001, I2: 0%). The use of metformin was significantly associated with a greater increase in OS and CSS rate and a greater decrease in recurrence rate in the Asian population than in the Western population.

CONCLUSION

The use of metformin in diabetic patients with GC can be associated with improved OS, CSS, RFS, and reduced recurrence rate after gastrectomy, especially in the Asian population.

Identification of glucose-independent and reversible metabolic pathways associated with anti-proliferative effect of metformin in liver cancer cells

INTRODUCTION

Despite the ability of cancer cells to survive glucose deprivation, most studies on anti-cancer effect of metformin explored its impact on glucose metabolism. No study ever examined whether its anti-cancer effect is reversible. Existing evidences warrant understanding of glucose-independent non-cytotoxic anti-proliferative effect of metformin to rationalize its role in liver cancer.

OBJECTIVES

Characterization of glucose-independent anti-proliferative metabolic effects of metformin as well as analysis of their reversibility in liver cancer cells.

METHODOLOGY

The dose-dependent effects of metformin on HepG2 cells were examined in presence and absence of glucose. The longitudinal evolution of metabolome was analyzed along with gene and protein expression as well as their correlations with and reversibility of cellular phenotype and metabolic signatures.

RESULTS

Metformin concentrations up to 2.5 mM were found to be anti-proliferative irrespective of presence of glucose without significant increase in cytotoxicity. Apart from mitochondrial impairment, derangement of fatty acid desaturation, one-carbon, glutathione, and polyamine metabolism were associated with metformin treatment irrespective of glucose supplementation. Depletion of pantothenic acid, downregulation of essential amino acid uptake and metabolism alongside purine salvage were identified as novel glucose-independent effects of metformin. These were significantly correlated with cMyc expression and reduction in proliferation. Rescue experiments established reversibility upon metformin withdrawal and tight association between proliferation, metabotype, and cMyc expression.

CONCLUSIONS

The derangement of multiple glucose-independent metabolic pathways, which are often upregulated in therapy-resistant cancer, and concomitant cMyc downregulation coordinately contribute to the anti-proliferative effect of metformin in liver cancer cells. These are reversible and may influence its therapeutic utility.

Metformin Increases the Response of Cholangiocarcinoma Cells to Gemcitabine by Suppressing Pyruvate Kinase M2 to Activate Mitochondrial Apoptosis

BACKGROUND

Cholangiocarcinoma (CCA) is a malignant tumor with a high mortality rate. Resistance to chemotherapy remains a major challenge related to cancer treatment, and increasing the sensitivity of cancer cells to therapeutic drugs is a major focus of cancer treatment.

AIMS

We purposed to explore the role of Metformin in CCA involved in chemotherapeutic sensitivity and Pyruvate kinase M2 (PKM2) through regulating mitochondrial apoptosis in the present study.

METHODS

CCA cell lines of HCC9810 and RBE were treated with Metformin companied with antagonists or agonists of PKM2, cells sensitivity to Gemcitabine, cell migration and invasion along with apoptosis, which is mediated by JC-1 and LDH were assayed.

RESULTS

Our results indicated that Metformin and Gemcitabine exhibit synergistic effect on inhibition of cholangiocarcinoma cell viability, cell migration and invasion as well as promotion apoptosis of cholangiocarcinoma cells. In vivo, Metformin combined with Gemcitabine has cooperation in inhibiting the growth of cholangiocarcinoma cell-derived tumors. Moreover, Metformin and Gemcitabine inhibited expression of PKM2 and PDHB in HCC9810 and RBE.

CONCLUSION

Our study suggested that Metformin may increase the response of cholangiocarcinoma cells to Gemcitabine by suppressing PKM2 to activate mitochondrial apoptosis.

Metronomic cyclophosphamide and metformin inhibited tumor growth and repopulated tumor-infiltrating lymphocytes in an experimental carcinoma model

Metformin is a widely used antidiabetic biguanide. Retrospective data demonstrated the association of metformin use with survival benefit in multiple tumor types. Interest in repurposing metformin to treat cancer has not been translated into encouraging clinical benefit. In animal models, metformin activated cytotoxic T cells and exerted an immune-mediated anticancer effect. The current research was conducted to investigate the possible therapeutic benefit of metformin in combination with metronomic cyclophosphamide in an experimental cancer model. Ehrlich ascites carcinoma was injected into the subcutaneous tissue to induce solid tumors in syngeneic mice. Exponential solid tumor growth ensued and was effectively arrested with the administration of a cytotoxic dose of parenteral cyclophosphamide. Alternatively, oral metformin and continuous, low-dose cyclophosphamide significantly inhibited tumor growth relative to untreated mice. The drug combination was well tolerated. Histopathological examination of the tumor showed an increased number of tumor-infiltrating lymphocytes and enhanced expression of granzyme B by this drug combination. The current data suggests a potential role of metformin and metronomic chemotherapy that warrants further investigation.

Current and novel approaches in the pharmacological treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most lethal malignant tumours worldwide. The mortality-to-incidence ratio is up to 91.6% in many countries, representing the third leading cause of cancer-related deaths. Systemic drugs, including the multikinase inhibitors sorafenib and lenvatinib, are first-line drugs used in HCC treatment. Unfortunately, these therapies are ineffective in most cases due to late diagnosis and the development of tumour resistance. Thus, novel pharmacological alternatives are urgently needed. For instance, immune checkpoint inhibitors have provided new approaches targeting cells of the immune system. Furthermore, monoclonal antibodies against programmed cell death-1 have shown benefits in HCC patients. In addition, drug combinations, including first-line treatment and immunotherapy, as well as drug repurposing, are promising novel therapeutic alternatives. Here, we review the current and novel pharmacological approaches to fight HCC. Preclinical studies, as well as approved and ongoing clinical trials for liver cancer treatment, are discussed. The pharmacological opportunities analysed here should lead to significant improvement in HCC therapy.

Metformin and HER2-positive breast cancer: Mechanisms and therapeutic implications

Due to the strong association between diabetes and cancer incidents, several anti-diabetic drugs, including metformin, have been examined for their anticancer activity. Metformin is a biguanide antihyperglycemic agent used as a first-line drug for type II diabetes mellitus. It exhibits anticancer activity by impacting different molecular pathways, such as AMP-inducible protein kinase (AMPK)-dependent and AMPK-independent pathways. Additionally, Metformin indirectly inhibits IGF-1R signaling, which is highly activated in breast malignancy. On the other hand, breast cancer is one of the major causes of cancer-related morbidity and mortality worldwide, where the human epidermal growth factor receptor-positive (HER2-positive) subtype is one of the most aggressive ones with a high rate of lymph node metastasis. In this review, we summarize the association between diabetes and human cancer, listing recent evidence of metformin's anticancer activity. A special focus is dedicated to HER2-positive breast cancer with regards to the interaction between HER2 and IGF-1R. Then, we discuss combination therapy strategies of metformin and other anti-diabetic drugs in HER2-positive breast cancer.

Action Mechanism of Metformin and Its Application in Hematological Malignancy Treatments: A Review

Hematologic malignancies (HMs) mainly include acute and chronic leukemia, lymphoma, myeloma and other heterogeneous tumors that seriously threaten human life and health. The common effective treatments are radiotherapy, chemotherapy and hematopoietic stem cell transplantation (HSCT), which have limited options and are prone to tumor recurrence and (or) drug resistance. Metformin is the first-line drug for the treatment of type 2 diabetes (T2DM). Recently, studies identified the potential anti-cancer ability of metformin in both T2DM patients and patients that are non-diabetic. The latest epidemiological and preclinical studies suggested a potential benefit of metformin in the prevention and treatment of patients with HM. The mechanism may involve the activation of the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway by metformin as well as other AMPK-independent pathways to exert anti-cancer properties. In addition, combining current conventional anti-cancer drugs with metformin may improve the efficacy and reduce adverse drug reactions. Therefore, metformin can also be used as an adjuvant therapeutic agent for HM. This paper highlights the anti-hyperglycemic effects and potential anti-cancer effects of metformin, and also compiles the in vitro and clinical trials of metformin as an anti-cancer and chemosensitizing agent for the treatment of HM. The need for future research on the use of metformin in the treatment of HM is indicated.

Impact of type 2 diabetes mellitus on the prognosis of patients with hepatocellular carcinoma after laparoscopic liver resection: A multicenter retrospective study

Background

The effect of type 2 diabetes mellitus (T2DM) on survival of patients with hepatocellular carcinoma (HCC) after laparoscopic liver resection (LLR) has not been reported. This study aimed to explore the relationship between preoperative T2DM and long-term prognosis in HCC patients undergoing LLR.

Methods

HCC patients receiving LLR as initial treatment at four cancer centers were retrospectively included in this study. Clinicopathological factors associated with the prognosis of HCC patients were identified using univariate and multivariate Cox regression analysis. Recurrence-free survival (RFS) and overall survival (OS) curves between different cohorts of patients were generated using the Kaplan-Meier method and compared using the log-rank test.

Results

Of 402 HCC patients included, 62 patients had T2DM and 340 patients did not have T2DM. The OS and RFS of patients with T2DM were significantly worse compared to those without T2DM (P = 0.001 and 0.032, respectively). In Cox multivariate analysis, T2DM was identified as an independent risk factors for OS (HR = 2.31, 95% CI = 1.38-3.85, P = 0.001) and RFS (HR = 1.66, 95% CI = 1.08-2.55, P = 0.020).

Conclusions

Following laparoscopic surgical approach, HCC patients with T2DM had poorer prognoses than those without T2DM. Preoperative T2DM was an independent risk factor for HCC patients. Thus, patients with concurrent HCC and T2DM should be closely monitored after LLR.

Metformin administration is associated with enhanced response to transarterial chemoembolization for hepatocellular carcinoma in type 2 diabetes patients

Transarterial chemoembolization (TACE) is often used as a locoregional therapy for early hepatocellular carcinoma (HCC) when local ablation or resection are not feasible, but incomplete response and recurrence are commonly observed. In this study, we sought to determine the association between metformin administration and TACE outcomes for single nodular HCC in patients with type 2 diabetes mellitus (T2DM). The retrospective cohort analysis included 164 T2DM patients with single nodular HCC who underwent TACE as an initial treatment, and 91 were exposed to metformin before and after TACE. Propensity score (PS) matching was used to balance covariates. Logistic regression analysis was used to determine the predictors of tumor response after TACE, and Cox regression analysis assessed independent predictors of local tumor recurrence (LTR) in patients with complete response after TACE. Metformin use was associated with significantly higher objective response rate (ORR) in the overall and PS-matched cohort (79.1% vs. 60.3 and 78.7% vs. 57.5%; p = 0.008 and p = 0.029, respectively). Logistic regression analysis showed that metformin use was an independent predictor of ORR in all and PS-matched patients (odds ratio = 2.65 and 3.06; p = 0.016 and 0.034, respectively). Cox regression analysis showed metformin administration was an independent predictor for lower LTR in all and PS-matched patients (hazard ratio = 0.28 and 0.27; p = 0.001 and 0.007, respectively). Metformin administration is associated with better initial response and lower local recurrence after TACE for single nodular HCC in T2DM.

Role of metformin in the diagnosis, prevention, and treatment of hepatocellular carcinoma

Hepatocellular carcinoma is one of the most common malignant tumors in the world. Although there are many options for the treatment of hepatocellular carcinoma, such as surgical resection, interventional therapy, radiotherapy, chemotherapy, targeted therapy and liver transplantation, the poor therapeutic effect seriously reduces the quality of life for patients and also increases the social and economic burden. Metformin is originally used as the first-line drug for type 2 diabetes, but it has been found to play a certain effect in the prevention and treatment of malignant tumor. The potential roles of metformin against hepatocellular carcinoma, such as regulation of the microenvironment, proliferation signal pathway, metabolism, invasion and metastasis, apoptosis, autophagy, and epigenetics of hepatoma cells. It provides a new choice for the prevention and treatment of hepatocellular carcinoma.

Effects of early medication treatment and metformin use for cancer prevention in diabetes patients: a nationwide sample cohort study using extended landmark-time analysis

OBJECTIVES

This study investigated the effectiveness of early medication treatment and metformin use for cancer prevention in type 2 diabetes patients.

METHODS

Population-based cohort data were used from the Korean National Health Insurance Service-National Sample Cohort database (KNHIS-NSC) for 2002–2013. Patient-specific medication prescription status was defined by the landmark time (LMT; a fixed time after cohort entry), considering both pre- and post-LMT prescriptions to control methodological biases in observational research. The LMT was set to 2 years. Logistic regression analysis with multivariable adjustment was conducted to analyze cancer incidence by patient-specific medication prescription status.

RESULTS

Only 33.4% of the subjects were prescribed medication early (before the LMT) with compliance. Cancer incidence in individuals with early prescription and compliance was 25% lower (odds ratio [OR], 0.75; 95% confidence interval [CI], 0.67 to 0.84) than in those without. As early-prescribed medications, metformin monotherapy and metformin combination therapy were associated with 34% (OR, 0.66; 95% CI, 0.51 to 0.83) and 25% (OR, 0.75; 95% CI, 0.64 to 0.88) lower cancer risk than non-use, respectively. Patients who were prescribed late (post-LMT) but did not comply with the prescription had a 24% (OR, 1.24; 95% CI, 0.97 to 1.58) higher cancer incidence than non-users. Among patients who started monotherapy early without changes throughout the entire follow-up period, those who started on metformin had a 37% (OR, 0.63; 95% CI, 0.41 to 0.99) lower risk of cancer than non-metformin users.

CONCLUSIONS

Doctors must prescribe antidiabetic medication early, and patient compliance is required, regardless of the prescription time, to prevent cancer. Metformin monotherapy or combination therapy is recommended as an early prescription.

Metformin Treatment or PRODH/POX-Knock out Similarly Induces Apoptosis by Reprograming of Amino Acid Metabolism, TCA, Urea Cycle and Pentose Phosphate Pathway in MCF-7 Breast Cancer Cells

It has been considered that proline dehydrogenase/proline oxidase (PRODH/POX) is involved in antineoplastic activity of metformin (MET). The aim of this study is identification of key metabolites of glycolysis, pentose phosphate pathway (PPP), tricarboxylic acids (TCA), urea cycles (UC) and some amino acids in MET-treated MCF-7 cells and PRODH/POX-knocked out MCF-7 (MCF-7^crPOX) cells. MCF-7^crPOX cells were generated by using CRISPR-Cas9. Targeted metabolomics was performed by LC-MS/MS/QqQ. Expression of pro-apoptotic proteins was evaluated by Western blot. In the absence of glutamine, MET treatment or PRODH/POX-knock out of MCF-7 cells contributed to similar inhibition of glycolysis (drastic increase in intracellular glucose and pyruvate) and increase in the utilization of phospho-enol-pyruvic acid, glucose-6-phosphate and some metabolites of TCA and UC, contributing to apoptosis. However, in the presence of glutamine, MET treatment or PRODH/POX-knock out of MCF-7 cells contributed to utilization of some studied metabolites (except glucose), facilitating pro-survival phenotype of MCF-7 cells in these conditions. It suggests that MET treatment or PRODH/POX-knock out induce similar metabolic effects (glucose starvation) and glycolysis is tightly linked to glutamine metabolism in MCF-7 breast cancer cells. The data provide insight into mechanism of anticancer activity of MET as an approach to further studies on experimental breast cancer therapy.

Enhanced Antiproliferation Potency of Electrical Pulse-Mediated Metformin and Cisplatin Combination Therapy on MDA-MB-231 Cells

We investigated the combined potency of metformin and cisplatin on the MDA-MB-231, triple-negative breast cancer (TNBC) cells with the application of electrical pulses. There are no targeted therapies for this subset of breast cancer because of the absence of specific biomarkers. Cytotoxic chemotherapy is the mainstream mode of treatment for TNBC, and cisplatin is the most commonly used chemotherapeutic drug. While there is a good response initially, TNBC cells develop drug resistance eventually. Thus, there is a need for alternate therapies. Toward this, we studied the antiproliferation characteristics of electrical pulse-mediated combination therapy using metformin, the commonly used Type-2 diabetes drug, along with cisplatin. We used metformin, as it has various anticancer properties caused by repressing energy pathways in a cancer cell. Application of 8 pulses of 1000 V/cm, 100 µs, at 1 Hz frequency, enhanced the drug uptake leading to cell viability as low as 25.86% at 30 µM cisplatin and 5 mM metformin in a 24 h study. Also, the same studies were conducted on MCF10A, a non-cancerous human epithelial cell. It aided in comparing the result for both MDA-MB-231 and MCF10A cell lines while establishing a better understanding of the experimental outcomes. Overall, the various experimental results from colony-forming assay, reactive oxidative analysis, and the intracellular glucose metabolic assay indicate the possibility of the electrical pulses-based cisplatin and metformin drug combination as a potential alternative to TNBC treatment.

Meta-analysis: The efficacy of metformin and other anti-hyperglycemic agents in prolonging the survival of hepatocellular carcinoma patients with type 2 diabetes

INTRODUCTION

This study aimed to compare the therapeutic efficacy of metformin and other anti-hyperglycemic agents in hepatocellular carcinoma (HCC) patients with type 2 diabetes (T2D).

MATERIALS

A systematic electronic search on keywords including HCC and different anti-hyperglycemic agents was performed through electronic databases including Medline and EMBASE. The primary outcome was the overall survival (OS). The secondary outcomes were the recurrence-free survival (RFS) and progression-free survival (PFS).

RESULTS

Six retrospective cohort studies were included for analysis: Four studies with curative treatment for HCC (618 patients with metformin and 532 patients with other anti-hyperglycemic agents) and two studies with non-curative treatment for HCC (92 patients with metformin and 57 patients with other anti-hyperglycemic agents). Treatment with metformin was associated with significantly longer OS (OR_1yr=2.62, 95%CI: 1.76-3.90; OR_3yr=3.14, 95%CI: 2.33-4.24; OR_5yr=3.31, 95%CI: 2.39-4.59, all P<0.00001) and RFS (OR_1yr=2.52, 95%CI: 1.84-3.44; OR_3yr=2.87, 95%CI: 2.15-3.84; all P<0.00001; and OR_5yr=2.26, 95%CI: 0.94-5.45, P=0.07) rates vs. those of other anti-hyperglycemic agents after curative therapies for HCC. However, both of the two studies reported that following non-curative HCC treatment, there were no significant differences in the OS and PFS rates between the metformin and non-metformin groups (I²>50%).

CONCLUSIONS

Metformin significantly prolonged the survival of HCC patients with T2D after the curative treatment of HCC. However, the efficacy of metformin needs to be further determined after non-curative therapies for HCC patients with T2D.

Prognostic Significance of VEGF and HIF-1 α in Hepatocellular Carcinoma Patients Receiving Sorafenib Versus Metformin Sorafenib Combination

BACKGROUND

Hepatocellular carcinoma (HCC) is a major health problem. HCC burden has been increasing in Egypt in the past 10 years. Most HCC cases are diagnosed at an advanced stage with limited treatment options. Sorafenib is the standard therapy for advanced HCC, but the effectiveness is not satisfied. Metformin may decrease the risk of HCC development in diabetic patients, reduces tumor invasion, and augments sensitivity to sorafenib; however, safety and efficacy of combined treatment are still unclear. As HCC is characterized by high vascularity, and vascular endothelial growth factor (VEGF) plays an important role in vascularization, many studies questioned if VEGF and HIF-1 α could offer information about HCC response to sorafenib. We conducted this study to assess the benefits from adding metformin to HCC treatment, and appraise the role of VEGF and HIF-1 α in HCC prognosis.

METHOD

This was a prospective, randomized study in which 80 advanced measurable patients consecutively treated with sorafenib plus metformin (arm A) or sorafenib alone (arm B), prognostic value of plasma, and tissue levels of VEGF and HIF-1 α were evaluated.

RESULTS

We enrolled 61 men and 19 women with a median age of 60 years (range 49-68 years). Fifty-seven patients had Child-Pugh A while 23 had early B, the most common etiology of liver disease was hepatitis C (86%). Sixty percent of patients were diabetic. No significant difference was detected between arm A and arm B regarding response to treatment (p = 0.5), time to disease progression (p = 0.3), or overall survival (p = 0.6). Low VEGF and HIF-1 α plasma levels were significantly associated with better treatment response (p < 0.001 for both), and higher OS (p < 0.001). Patients with high expressions of VEGF and HIF in HCC tissue had significantly poor treatment outcome (p < 0.001, p = 0.03, respectively), and poor OS (p < 0.001, p < 0.001, respectively).

CONCLUSIONS

No superior efficacy of adding metformin to sorafenib in HCC treatment. VEGF and HIF-1 α had promising prognostic value in HCC.

Repurposing metformin for the treatment of gastrointestinal cancer

Diabetes mellitus type 2 and cancer share many risk factors. The pleiotropic insulin-dependent and insulin-independent effects of metformin might inhibit pathways that are frequently amplified in neoplastic tissue. Particularly, modulation of inflammation, metabolism, and cell cycle arrest are potential therapeutic cancer targets utilized by metformin to boost the anti-cancer effects of chemotherapy. Studies in vitro and in vivo models have demonstrated the potential of metformin as a chemo- and radiosensitizer, besides its chemopreventive and direct therapeutic activity in digestive system (DS) tumors. Hence, these aspects have been considered in many cancer clinical trials. Case-control and cohort studies and associated meta-analyses have evaluated DS cancer risk and metformin usage, especially in colorectal cancer, pancreatic cancer, and hepatocellular carcinoma. Most clinical studies have demonstrated the protective role of metformin in the risk for DS cancers and survival rates. On the other hand, the ability of metformin to enhance the actions of chemotherapy for gastric and biliary cancers is yet to be investigated. This article reviews the current findings on the anti-cancer mechanisms of metformin and its apparatus from pre-clinical and ongoing studies in DS malignancies.

Metformin Modulates T Cell Function and Alleviates Liver Injury Through Bioenergetic Regulation in Viral Hepatitis

Metformin is not only the first-line medication for the treatment of type 2 diabetes, but it is also effective as an anti-inflammatory, anti-oxidative and anti-tumor agent. However, the effect of metformin during viral hepatitis remains elusive. Using an adenovirus (Ad)-induced viral hepatitis mouse model, we found that metformin treatment significantly attenuated liver injury, with reduced serum aspartate transaminase (AST) and alanine transaminase (ALT) levels and liver histological changes, presumably via decreased effector T cell responses. We then demonstrated that metformin reduced mTORC1 activity in T cells from infected mice, as evidenced by decreased phosphorylation of ribosome protein S6 (p-S6). The inhibitory effects on the mTORC1 signaling by metformin was dependent on the tuberous sclerosis complex 1 (TSC1). Mechanistically, metformin treatment modulated the phosphorylation of dynamin-related protein 1 (Drp-1) and mitochondrial fission 1 protein (FIS1), resulting in increased mass in effector T cells. Moreover, metformin treatment promoted mitochondrial superoxide production, which can inhibit excessive T cell activation in viral hepatitis. Together, our results revealed a protective role and therapeutic potential of metformin against liver injury in acute viral hepatitis via modulating effector T cell activation via regulating the mTORC1 pathway and mitochondrial functions.

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.

New tricks of old drugs: Repurposing non-chemo drugs and dietary phytochemicals as adjuvants in anti-tumor therapies

Combination therapy has long been applied to enhance therapeutic effect and deal with the occurrence of multi-drug resistance in cancer treatment. However, the overlapping toxicity of multiple anticancer drugs to healthy tissues and increasing financial burden on patients emerged as major concerns. As promising alternatives to chemo agents, repurposed non-chemo drugs and dietary phytochemicals have been investigated as adjuvants to conventional anti-tumor therapeutics, offering a safe and economic strategy for combination therapy. In this review, we aim to highlight the advances in research about combination therapy using conventional therapeutics and repurposed drugs or phytochemicals for an enhanced anti-tumor efficacy, along with the mechanisms involved in the synergism. Beyond these, we outlined the potential challenges and solutions for clinical translation of the proposed combination therapy, providing a safe and affordable strategy to improve the reach of cancer therapy to low income regions with such new tricks of old drugs.

Exercise Improves Outcomes of Surgery on Fatty Liver in Mice: A Novel Effect Mediated by the AMPK Pathway

OBJECTIVE

To investigate whether exercise improves outcomes of surgery on fatty liver, and whether pharmacological approaches can substitute exercising programs.

SUMMARY OF BACKGROUND DATA

Steatosis is the hepatic manifestation of the metabolic syndrome, and decreases the liver's ability to handle inflammatory stress or to regenerate after tissue loss. Exercise activates adenosine monophosphate-activated kinase (AMPK) and mitigates steatosis; however, its impact on ischemia-reperfusion injury and regeneration is unknown.

METHODS

We used a mouse model of simple, diet-induced steatosis and assessed the impact of exercise on metabolic parameters, ischemia-reperfusion injury and regeneration after hepatectomy. The same parameters were evaluated after treatment of mice with the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR). Mice on a control diet served as age-matched controls.

RESULTS

A 4-week-exercising program reversed steatosis, lowered insulin levels, and improved glucose tolerance. Exercise markedly enhanced the ischemic tolerance and the regenerative capacity of fatty liver. Replacing exercise with AICAR was sufficient to replicate the above benefits. Both exercise and AICAR improved survival after extended hepatectomy in mice challenged with a Western diet, indicating protection from resection-induced liver failure.

CONCLUSIONS

Exercise efficiently counteracts the metabolic, ischemic, and regenerative deficits of fatty liver. AICAR acts as an exercise mimetic in settings of fatty liver disease, an important finding given the compliance issues associated with exercise. Exercising, or its substitution through AICAR, may provide a feasible strategy to negate the hepatic consequences of energy-rich diet, and has the potential to extend the application of liver surgery if confirmed in humans.

Diabetes and its Potential Impact on Head and Neck Oncogenesis

In recent years, the incidence of diabetes mellitus and cancer has increased sharply; indeed, these have become the two most important diseases threatening health and survival. Head and neck (HN) tumors are the sixth most common malignancies in humans. Numerous studies have shown that there are many common risk factors for diabetes mellitus and HN squamous cell carcinoma, including advanced age, poor diet and lifestyle, and environmental factors. However, the mechanism linking the two diseases has not been identified. A number of studies have shown that diabetes affects the development, metastasis, and prognosis of HN cancer, potentially through the associated hyperglycemia, hyperinsulinemia and insulin resistance, or chronic inflammation. More recent studies show that metformin, the first-line drug for the treatment of type 2 diabetes, can significantly reduce the risk of HN tumor development and reduce mortality in diabetic patients. Here, we review recent progress in the study of the relationship between diabetes mellitus and HN carcinogenesis, and its potential mechanisms, in order to provide a scientific basis for the early diagnosis and effective treatment of these diseases.

Diabetes Mellitus and Metformin Are Not Associated With Breast Cancer Pathologic Complete Response

BACKGROUND

Metformin use has been linked to pathologic complete response (pCR) following neoadjuvant chemotherapy for several malignancies. We aimed to investigate the association of diabetes mellitus (DM) and metformin use with pCR in breast cancer.

MATERIALS AND METHODS

All breast cancer patients who received neoadjuvant chemotherapy during June 2013-October 2016 at two academic medical centers were identified. A retrospective cohort study evaluated patients who did and did not achieve pCR. Multivariable logistic regression identified independent predictors of pCR, specifically looking at metformin use and DM.

RESULTS

The study group included 351 breast cancer patients, with 90 (25.6%) achieving pCR after neoadjuvant chemotherapy. The rate of DM did not differ between those with and without pCR, nor did the rate of metformin use. Multivariable logistic regression identified HER2-positive tumors and smaller preoperative tumor size as predictors of pCR. The estrogen receptor (ER) positivity was associated with an absence of pCR. Importantly, neither DM nor metformin use was predictive of pCR.

CONCLUSIONS

This study by the two institutions supports previous data of tumor-related factors known to be associated with pCR; however, the current analysis found neither DM nor metformin to be independently associated with pCR. Thus, additional prospective study is warranted prior to validating metformin as an antitumor agent.

Role of p53 Family Proteins in Metformin Anti-Cancer Activities

Metformin has been used as therapy for type 2 diabetes for many years. Clinical and basic evidence as indicated that metformin has anti-cancer activities. It has been well-established that metformin activates AMP-activated protein kinase (AMPK), which in turn regulates energy homeostasis. However, the mechanistic aspects of metformin anti-cancer activity remain elusive. p53 family proteins, including p53, p63 and p73, have diverse biological functions, including regulation of cell growth, survival, development, senescence and aging. In this review, we highlight the evidence and mechanisms by which metformin inhibits cancer cell survival and tumor growth. We also aimed to discuss the role of p53 family proteins in metformin-mediated suppression of cancer growth and survival.

PYK2 promotes HER2-positive breast cancer invasion

BACKGROUND

Metformin, a biguanide, is one of the most commonly prescribed treatments for type 2 diabetes and has recently been recommended as a potential drug candidate for advanced cancer therapy. Although Metformin has antiproliferative and proapoptotic effects on breast cancer, the heterogenous nature of this disease affects the response to metformin leading to the activation of pro-invasive signalling pathways that are mediated by the focal adhesion kinase PYK2 in pure HER2 phenotype breast cancer.

METHODS

The effect of metformin on different breast cancer cell lines, representing the molecular heterogenicity of the disease was investigated using in vitro proliferation and apoptosis assays. The activation of PYK2 by metformin in pure HER2 phenotype (HER2+/ER-/PR-) cell lines was investigated by microarrays, quantitative real time PCR and immunoblotting. Cell migration and invasion PYK2-mediated and in response to metformin were determined by wound healing and invasion assays using HER2+/ER-/PR- PYK2 knockdown cell lines. Proteomic analyses were used to determine the role of PYK2 in HER2+/ER-/PR- proliferative, migratory and invasive cellular pathways and in response to metformin. The association between PYK2 expression and HER2+/ER-/PR- patients' cancer-specific survival was investigated using bioinformatic analysis of PYK2 expression from patient gene expression profiles generated by the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) study. The effect of PYK2 and metformin on tumour initiation and invasion of HER2+/ER-/PR- breast cancer stem-like cells was performed using the in vitro stem cell proliferation and invasion assays.

RESULTS

Our study showed for the first time that pure HER2 breast cancer cells are more resistant to metformin treatment when compared with the other breast cancer phenotypes. This drug resistance was associated with the activation of PTK2B/PYK2, a well-known mediator of signalling pathways involved in cell proliferation, migration and invasion. The role of PYK2 in promoting invasion of metformin resistant HER2 breast cancer cells was confirmed through investigating the effect of PYK2 knockdown and metformin on cell invasion and by proteomic analysis of associated cellular pathways. We also reveal a correlation between high level of expression of PYK2 and reduced survival in pure HER2 breast cancer patients. Moreover, we also report a role of PYK2 in tumour initiation and invasion-mediated by pure HER2 breast cancer stem-like cells. This was further confirmed by demonstrating a correlation between reduced survival in pure HER2 breast cancer patients and expression of PYK2 and the stem cell marker CD44.

CONCLUSIONS

We provide evidence of a PYK2-driven pro-invasive potential of metformin in pure HER2 cancer therapy and propose that metformin-based therapy should consider the molecular heterogeneity of breast cancer to prevent complications associated with cancer chemoresistance, invasion and recurrence in treated patients.

Adiponectin accounts for gender differences in hepatocellular carcinoma incidence

Gender disparity in liver cancer incidence is a relevant feature of this malignancy. Manieri et al. show that testosterone-induced JNK1 activation in adipose tissue results in decreased levels of circulating adiponectin, which is responsible for higher incidence of hepatocellular carcinoma in males.

Hepatocellular carcinoma (HCC) is the sixth most common cancer type and the fourth leading cause of cancer-related death. This cancer appears with higher incidence in men and during obesity; however, the specific mechanisms underlying this correlation are unknown. Adipose tissue, a key organ in metabolic syndrome, shows evident gender disparities in the production of adipokines. Levels of the important adipokine adiponectin decrease in men during puberty, as well as in the obese state. Here, we show that this decrease in adiponectin levels is responsible for the increased liver cancer risk in males. We found that testosterone activates the protein JNK in mouse and human adipocytes. JNK-mediated inhibition of adiponectin secretion increases liver cancer cell proliferation, since adiponectin protects against liver cancer development through the activation of AMP-activated protein kinase (AMPK) and p38α. This study provides insight into adipose tissue to liver crosstalk and its gender relation during cancer development, having the potential to guide strategies for new cancer therapeutics.

Anti-proliferative and anti-apoptotic potential effects of epigallocatechin-3-gallate and/or metformin on hepatocellular carcinoma cells: in vitro study

The effects of epigallocatechin-3-gallate (EGCG) and metformin single treatment have been tested against hepatocellular carcinoma (HCC). This study aimed to assess the combination effects of EGCG and metformin on proliferation and apoptosis of HepG2cells and identified new potential molecular targets. The effect of EGCG and metformin against cell proliferation in HepG2 was determined using MTT assay. Reverse transcription polymerase chain reaction was applied to examine the gene expression of cyclin D1, lncRNA-AF085935, caspase-3, survivin and VEGF. The level of protein expression of glypican-3 was assessed by western blot. In HepG2 cells, EGCG and metformin combination treatment exhibited high significant effect against tumor proliferation. It significantly reduced cyclin D1, lncRNA-AF085935, glypican-3 and promoted apoptosis through increasing caspase3 and decreasing survivin compared to control cells. Moreover, EGCG and metformin treated cells showed decreased expression levels of VEGF. Our study provided new insights of the anticarcinogenic effects of EGCG and metformin on HCC through their effects on glypican-3 and lncRNA-AF085935.

The Potential Effect of Metformin on Cancer: An Umbrella Review

Background: Metformin has been reported to possess anti-cancer properties in addition to glucose-lowering activity and numerous systematic reviews and meta-analyses have studied the association between metformin use and cancer incidence or survival outcomes. We performed an umbrella review to assess the robustness of these associations to facilitate proper interpretation of these results to inform clinical and policy decisions. Methods: We searched PubMed and Embase systematic reviews and meta-analyses investigating the effect of metformin use on cancer incidence or survival outcomes published from inception to September 2, 2018. We estimated the summary effect size, the 95% CI, and the 95% prediction interval, heterogeneity, evidence of small-study effects, and evidence of excess significance bias. Results: We included 21 systematic reviews and meta-analyses covering 11 major anatomical sites and 33 associations. There was strong evidence for the association between metformin use and decreased pancreatic cancer incidence. The association between metformin use and improved colorectal cancer overall survival (OS) was supported by highly suggestive evidence. Seven associations (all cancer incidence, all cancer OS, breast cancer OS, colorectal cancer incidence, liver cancer incidence, lung cancer OS, and pancreatic cancer OS) presented only suggestive evidence. The remaining 24 associations were supported by weak or not-suggestive evidence. Conclusions: Associations between metformin use and pancreatic cancer incidence or colorectal cancer OS are supported by strong or highly suggestive evidence, respectively. However, these results should be interpreted with caution due to the poor methodological quality of the systematic reviews and meta-analyses.

Metformin as a Radiation Modifier; Implications to Normal Tissue Protection and Tumor Sensitization

BACKGROUND

Nowadays, ionizing radiation is used for several applications in medicine, industry, agriculture, and nuclear power generation. Besides the beneficial roles of ionizing radiation, there are some concerns about accidental exposure to radioactive sources. The threat posed by its use in terrorism is of global concern. Furthermore, there are several side effects to normal organs for patients who had undergone radiation treatment for cancer. Hence, the modulation of radiation response in normal tissues was one of the most important aims of radiobiology. Although, so far, several agents have been investigated for protection and mitigation of radiation injury. Agents such as amifostine may lead to severe toxicity, while others may interfere with radiation therapy outcomes as a result of tumor protection. Metformin is a natural agent that is well known as an antidiabetic drug. It has shown some antioxidant effects and enhances DNA repair capacity, thereby ameliorating cell death following exposure to radiation. Moreover, through targeting endogenous ROS production within cells, it can mitigate radiation injury. This could potentially make it an effective radiation countermeasure. In contrast to other radioprotectors, metformin has shown modulatory effects through induction of several genes such as AMPK, which suppresses reduction/ oxidation (redox) reactions, protects cells from accumulation of unrepaired DNA, and attenuates initiation of inflammation as well as fibrotic pathways. Interestingly, these properties of metformin can sensitize cancer cells to radiotherapy.

CONCLUSION

In this article, we aimed to review the interesting properties of metformin such as radioprotection, radiomitigation and radiosensitization, which could make it an interesting adjuvant for clinical radiotherapy, as well as an interesting candidate for mitigation of radiation injury after a radiation disaster.

Repurposing old drugs in oncology: Opportunities with clinical and regulatory challenges ahead

WHAT IS KNOWN AND OBJECTIVE

In order to expedite the availability of drugs to treat cancers in a cost-effective manner, repurposing of old drugs for oncological indications is gathering momentum. Revolutionary advances in pharmacology and genomics have demonstrated many old drugs to have activity at novel antioncogenic pharmacological targets. We decided to investigate whether prospective studies support the promises of nonclinical and retrospective clinical studies on repurposing three old drugs, namely metformin, valproate and astemizole.

METHODS

We conducted an extensive literature search through PubMed to gather representative nonclinical and retrospective clinical studies that investigated the potential repurposing of these three drugs for oncological indications. We then searched for prospective studies aimed at confirming the promises of retrospective data.

RESULTS AND DISCUSSION

While evidence from nonclinical and retrospective clinical studies with these drugs appears highly promising, large scale prospective studies are either lacking or have failed to substantiate this promise. We provide a brief discussion of some of the challenges in repurposing. Principal challenges and obstacles relate to heterogeneity of cancers studied without considering their molecular signatures, trials with small sample size and short duration, failure consider issues of ethnicity of study population and effective antioncogenic doses of the drug studied.

WHAT IS NEW AND CONCLUSION

Well-designed prospective studies demonstrating efficacy are required for repurposing old drugs for oncology indications, just as they are for new chemical entities for any indication. Early and ongoing interactions with regulatory authorities are invaluable. We outline a tentative framework for a structured approach to repurposing old drugs for novel indications in oncology.

Metformin and blood cancers

Type 2 diabetes mellitus and cancer are correlated with changes in insulin signaling, a pathway that is frequently upregulated in neoplastic tissue but impaired in tissues that are classically targeted by insulin in type 2 diabetes mellitus. Many antidiabetes treatments, particularly metformin, enhance insulin signaling, but this pathway can be inhibited by specific cancer treatments. The modulation of cancer growth by metformin and of insulin sensitivity by anticancer drugs is so common that this phenomenon is being studied in hundreds of clinical trials on cancer. Many meta-analyses have consistently shown a moderate but direct effect of body mass index on the incidence of multiple myeloma and lymphoma and the elevated risk of leukemia in adults. Moreover, new epidemiological and preclinical studies indicate metformin as a therapeutic agent in patients with leukemia, lymphomas, and multiple myeloma. In this article, we review current findings on the anticancer activities of metformin and the underlying mechanisms from preclinical and ongoing studies in hematologic malignancies.

Association of metformin intake with bladder cancer risk and oncologic outcomes in type 2 diabetes mellitus patients: A systematic review and meta-analysis

BACKGROUND

Recent clinical trials indicated that metformin intake might play a protective role in the incidence and oncologic outcomes of various cancers. However, its protective effect on bladder cancer remains uncertain.

METHODS

We performed a meta-analysis to investigate the association between metformin intake and bladder cancer risk as well as oncologic outcomes in diabetes mellitus (DM) patients. A comprehensive literature search was performed using PubMed, Embase, and the Cochrane Central Search Library in December 2017. Hazard ratio (HR) with 95% confidence interval (CI) was pooled.

RESULTS

A total of 9 retrospective cohort studies with 1,270,179 patients were included. A meta-analysis revealed that metformin intake was associated with an increased recurrence-free survival (HR = 0.55, 95% confidence interval [CI] = 0.35-0.88; P = .01; I = 64%), improved progression-free survival (HR = 0.70, 95% CI = 0.51-0.96; P = .03; I = 33%), and prolonged cancer-specific survival (HR = 0.57, 95% CI = 0.40-0.81; P = .002; I = 0%). However, results demonstrated that metformin intake was not associated with a decreased incidence of bladder cancer (HR = 0.82, 95% CI = 0.61-1.09; P = .17; I = 85%) or an increased overall survival in bladder cancer patients (HR = 0.83, 95% CI = 0.47-1.44; P = .50; I = 64%).

CONCLUSION

The present meta-analysis indicated that metformin intake could improve the prognosis of bladder cancer patients. Further prospective cohort studies and mechanistic studies are still required to determine the precise role of metformin in the initiation and progression of bladder cancer.

Metformin Targets Mitochondrial Glycerophosphate Dehydrogenase to Control Rate of Oxidative Phosphorylation and Growth of Thyroid Cancer In Vitro and In Vivo

Purpose: Mitochondrial glycerophosphate dehydrogenase (MGPDH) is the key enzyme connecting oxidative phosphorylation (OXPHOS) and glycolysis as well as a target of the antidiabetic drug metformin in the liver. There are no data on the expression and role of MGPDH as a metformin target in cancer. In this study, we evaluated MGPDH as a potential target of metformin in thyroid cancer and investigated its contribution in thyroid cancer metabolism.Experimental Design: We analyzed MGPDH expression in 253 thyroid cancer and normal tissues by immunostaining and examined its expression and localization in thyroid cancer-derived cell lines (FTC133, BCPAP) by confocal microscopy. The effects of metformin on MGPDH expression were determined by qRT-PCR and Western blot analysis. Seahorse analyzer was utilized to assess the effects of metformin on OXPHOS and glycolysis in thyroid cancer cells. We analyzed the effects of metformin on tumor growth and MGPDH expression in metastatic thyroid cancer mouse models.Results: We show for the first time that MGPDH is overexpressed in thyroid cancer compared with normal thyroid. We demonstrate that MGPDH regulates human thyroid cancer cell growth and OXPHOS rate in vitro Metformin treatment is associated with downregulation of MGPDH expression and inhibition of OXPHOS in thyroid cancer in vitro Cells characterized by high MGPDH expression are more sensitive to OXPHOS-inhibitory effects of metformin in vitro and growth-inhibitory effects of metformin in vitro and in vivoConclusions: Our study established MGPDH as a novel regulator of thyroid cancer growth and metabolism that can be effectively targeted by metformin. Clin Cancer Res; 24(16); 4030-43. ©2018 AACR.

Rosiglitazone reduces breast cancer risk in Taiwanese female patients with type 2 diabetes mellitus

This study investigated whether rosiglitazone may affect breast cancer risk in female patients with type 2 diabetes mellitus in Taiwan. The reimbursement database of all female patients with type 2 diabetes mellitus under oral antidiabetic agents or insulin from 1996 to 2009 was retrieved from the National Health Insurance. An entry date was set on 1 January 2006 and a total of 431447 patients were followed up for breast cancer incidence till the end of 2009. Incidences for ever users, never users and subgroups of rosiglitazone dose-response parameters (tertile cutoffs of cumulative duration and cumulative dose) were calculated and hazard ratios estimated by Cox regression. There were 53029 ever users and 378418 never users, respective numbers of incident breast cancer 410 (0.77%) and 3292 (0.87%), and respective incidence 217.53 and 249.12 per 100000 person-years. The overall hazard ratio was 0.889 (95% confidence interval: 0.797−0.992) in the fully adjusted model. Significantly lower risk was observed for the third tertiles of cumulative duration (> 14 months) and cumulative dose (> 1792 mg) while compared to never users, with respective adjusted hazard ratio of 0.815 (95% confidence interval: 0.682−0.973) and 0.815 (95% confidence interval: 0.682−0.974). Additionally, a significant interaction between metformin and rosiglitazone was observed. The lowest risk was seen in patients who used both drugs (hazard ratio 0.812, 95% confidence interval: 0.705−0.934). In conclusion, rosiglitazone reduces breast cancer risk in female patients with type 2 diabetes mellitus, which shows a significant interaction with metformin.

Metformin is associated with survival benefit in pancreatic cancer patients with diabetes: a systematic review and meta-analysis

Background

Pancreatic cancer is a highly lethal disease with a poor prognosis while metformin has been associated with a decreased risk of pancreatic cancer. Although the benefit of metformin was observed for pancreatic cancer prevention, it is not clear whether it can also affect the survival of pancreatic cancer patients with type 2 diabetes mellitus. A systematic review and meta-analysis was conducted to assess the effect of metformin on the survival of pancreatic cancer patients with type 2 diabetes mellitus.

Methods

Two independent authors searched PubMed and Web of science up to 08/07/2016. We assessed studies for eligibility, extracted data, and examined their quality, with the primary outcome as overall survival. We used published hazard ratio (HR) available or estimated based on other survival data. We pooled the data and used a random-effect model to combine direct comparisons from included articles. We also investigated treatment effects by different countries, quality and the time of metformin initiation.

RESULTS

We found that there was a relative survival benefit associated with metformin treatment compared with non-metformin treatment in both overall survival (OS) ([HR] 0.84; 95% confidence interval [CI]: 0.73 – 0.96). These associations were also observed in subgroups of Asian countries and high quality articles.

Conclusions

Our results support the notion that metformin maybe the best anti-diabetic medicine of choice in patients with pancreatic cancer and concurrent type 2 diabetes mellitus. The perspectives of enhancing survival of pancreatic cancer patients with diabetes mellitus by the use of metformin deserve more attention in future research and clinical practice.

Metformin as an anti-cancer agent: actions and mechanisms targeting cancer stem cells

Metformin, a first line medication for type II diabetes, initially entered the spotlight as a promising anti-cancer agent due to epidemiologic reports that found reduced cancer risk and improved clinical outcomes in diabetic patients taking metformin. To uncover the anti-cancer mechanisms of metformin, preclinical studies determined that metformin impairs cellular metabolism and suppresses oncogenic signaling pathways, including receptor tyrosine kinase, PI3K/Akt, and mTOR pathways. Recently, the anti-cancer potential of metformin has gained increasing interest due to its inhibitory effects on cancer stem cells (CSCs), which are associated with tumor metastasis, drug resistance, and relapse. Studies using various cancer models, including breast, pancreatic, prostate, and colon, have demonstrated the potency of metformin in attenuating CSCs through the targeting of specific pathways involved in cell differentiation, renewal, metastasis, and metabolism. In this review, we provide a comprehensive overview of the anti-cancer actions and mechanisms of metformin, including the regulation of CSCs and related pathways. We also discuss the potential anti-cancer applications of metformin as mono- or combination therapies.

Metformin inhibits the development, and promotes the resensitization, of treatment-resistant breast cancer

Multiple drug resistant (MDR) malignancy remains a predictable and often terminal event in cancer therapy, and affects individuals with many cancer types, regardless of the stage at which they were originally diagnosed or the interval from last treatment. Protein biomarkers of MDR are not globally used for clinical decision-making, but include the overexpression of drug-efflux pumps (ABC transporter family) such as MDR-1 and BCRP, as well as HIF1α, a stress responsive transcription factor found elevated within many MDR tumors. Here, we present the important in vitro discovery that the development of MDR (in breast cancer cells) can be prevented, and that established MDR could be resensitized to therapy, by adjunct treatment with metformin. Metformin is prescribed globally to improve insulin sensitivity, including in those individuals with Type 2 Diabetes Mellitus (DM2). We demonstrate the effectiveness of metformin in resensitizing MDR breast cancer cell lines to their original treatment, and provide evidence that metformin may function through a mechanism involving post-translational histone modifications via an indirect histone deacetylase inhibitor (HDACi) activity. We find that metformin, at low physiological concentrations, reduces the expression of multiple classic protein markers of MDR in vitro and in preliminary in vivo models. Our demonstration that metformin can prevent MDR development and resensitize MDR cells to chemotherapy in vitro, provides important medical relevance towards metformin’s potential clinical use against MDR cancers.

The 150 most important questions in cancer research and clinical oncology series: questions 76-85 : Edited by Chinese Journal of Cancer

Since the beginning of 2017, Chinese Journal of Cancer has published a series of important questions in cancer research and clinical oncology to promote cancer research and accelerate collaborations. In this article, 10 questions are presented as followed. Question 76. How to develop effective therapeutics for cancer cachexia? Question 77. How can we develop preclinical animal models to recapitulate clinical situations of cancer patients for more effective anti-cancer drug development? Question 78. How can we develop novel effective therapeutics for pancreatic cancer and hepatocellular carcinoma? Question 79. What are the true beneficial mechanisms of antiangiogenic therapy in cancer patients? Question 80. How to approach the complex mechanisms of interplay among various cellular and molecular components in the tumor microenvironment? Question 81. Can tissue oxygenation improve the efficacy of conventional chemotherapy on cancer? Question 82. Can tissue oxygenation improve the efficacy of radiotherapy on digestive system tumors including liver cancer? Question 83. Can we integrate metabolic priming into multimodal management of liver cancer? Question 84. Has the limit of anti-androgen strategy in prostate cancer treatment been reached by the new generation of anti-androgen drugs? Question 85. Can we identify individuals with early-stage cancers via analyzing their clinical and non-clinical information collected from social media, shopping history, and clinical, pathological, and molecular traces?

Repurposing metformin for the prevention of cancer and cancer recurrence

Multiple epidemiological studies have documented an association between metformin, used for treatment of type 2 diabetes, and reduced cancer incidence and mortality. Cell line models may not accurately reflect the effects of metformin in the clinical setting. Moreover, findings from animal model studies have been inconsistent, whilst those from more recent epidemiological studies have tempered the overall effect size. The purpose of this review is to examine metformin's chemopreventive potential by outlining relevant mechanisms of action, the most recent epidemiologic evidence, and recently completed and ongoing clinical trials. Although repurposing drugs with excellent safety profiles is an appealing strategy for cancer prevention and treatment in the adjuvant setting, there is no substitute for well-executed, large randomised clinical trials to define efficacy and determine the populations that are most likely to benefit from an intervention. Thus, enthusiasm remains for understanding the role of metformin in cancer through ongoing clinical research.

Metformin use and survival outcomes in endometrial cancer: a systematic review and meta-analysis

Previous studies have evaluated the effects of metformin use on survival outcomes in endometrial cancer, but their results are inconsistent. We conducted a systematic review and meta-analysis to provide a quantitative assessment of the drug's effects based on available evidence. We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials to identify relevant studies that evaluated the association between metformin use on survival outcomes in endometrial cancer. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated to evaluate the association of metformin use with overall survival and with progression-free survival using a fixed-effects model. A total of nine studies involving 2,016 patients with endometrial cancer were identified. In a meta-analysis of eight studies involving 1,594 individuals, metformin use was associated with significant improvements in overall survival (HR, 0.51; 95% CI, 0.41 to 0.64). Metformin users similarly showed improved progression-free survival in a meta-analysis of two studies involving 632 individuals (HR, 0.63; 95% CI, 0.46 to 0.87). In conclusion, endometrial cancer patients who use metformin show improved overall survival and progression-free survival. Further studies are required to confirm the full potential effects of metformin use on survival outcomes in endometrial cancer.

Metformin and endometrial cancer survival: a quantitative synthesis of observational studies

Metformin has been reported to have anticancer effect and can affect patient survival in several malignancies. However, the results are inconclusive for endometrial cancer. Hence, we conducted a systematic review and meta-analysis to investigate the prognostic role of metformin in patients with endometrial cancer. Studies were identified from Pubmed and Embase database through March 2017. Observational studies reporting hazard ratios (HRs) with 95% confidence intervals (CIs) for overall survival (OS) and progression-free survival (PFS) were selected. Data were abstracted and summarised using random-effects models. From 250 unique citations, we identified ten studies including 6242 patients with nine studies examining OS and five studies examining PFS. Meta-analysis demonstrated that metformin users had better OS (HR, 0.58; 95% CI, 0.45 to 0.76; P = 0.207, I² = 26.6%) and PFS (HR, 0.61; 95% CI, 0.49 to 0.76; P =0.768, I² = 0%) than non-users for endometrial cancer patients. Similar findings were observed using sensitivity analysis adjusted by trim and filled methods (HR, 0.47; 95% CI, 0.37 to 0.58) and subgroup analyses. Based on the current evidence, we find that metformin use is associated with better OS and PFS in patients with endometrial cancer. However, further large-scale prospective studies are needed to establish its validity.

Metformin Suppresses Proliferation and Viability of Rat Pheochromocytoma Cells

BACKGROUND Previous studies have clearly demonstrated that metformin inhibits cell proliferation and cell growth in many types of human cancers. Increased survival rates in patients with breast and lung cancer receiving metformin have also been observed. However, the effect of metformin on pheochromocytoma cells remains unexplored. MATERIAL AND METHODS Rat pheochromocytoma cells (PC12 cells) were cultured and treated with metformin or vehicle control. Cell proliferation, cell-cycle, apoptosis, genes expression, and the signaling pathways involved were analyzed in PC12 cells. RESULTS The metformin treatment reduced cell viability and proliferation in rat pheochromocytoma PC12 cells in a dose- and time-dependent manner. Furthermore, metformin exposure led to an increased apoptosis rate and cell-cycle arrest accompanied with downregulation of Ccna2 and Ccnb2. At the molecular level, the AMPK signaling pathway was activated, whereas the mTOR and ERK1/2 signaling pathways were inhibited by metformin. CONCLUSIONS Our data suggest an antiproliferative role of metformin in pheochromocytoma development, which may provide a novel option for future cancer therapy.

Metformin exhibits the anti-proliferation and anti-invasion effects in hepatocellular carcinoma cells after insufficient radiofrequency ablation

Background

The mechanisms and prevention of progression of hepatocellular carcinoma (HCC) after insufficient radiofrequency ablation (RFA) has been preliminarily investigated, therefore, new strategy needs to be investigated to prevent the process. Whether metformin could be used to inhibit the growth of HCC after insufficient RFA and further prevent the progression of residual HCC remains unclearly.

Methods

MTT assay, colony formation assay and transwell assay were used to observe the cell viability, migration and invasion. Western blot and immunohistochemistry methods were used to observe the expression of proteins. Xenograft model was used to evaluate the growth of HCC cells in vivo.

Results

Metformin inhibited the enhanced proliferation, migration and invasion of HepG2 and SMMC7721 cells after insufficient RFA (named as HepG2-H and SMMC7721-H). Metformin deregulated the expression of p-Akt in HepG2 and SMMC7721 cells after insufficient RFA through AMPK/PTEN pathway. HepG2-H cells also exhibited larger tumor size in vivo. Higher expression of Ki-67 and CD31 and lower expression of E-cadherin were observed in HepG2-H tumors. Metformin blocked the enhanced growth of HepG2 cells in vivo after insufficient RFA. Metformin had no apparent toxicity on nude mice.

Conclusions

Metfromin inhibited the growth of HCC cells after insufficient RFA, and may be used to prevent the progression of HCC after RFA.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-017-0418-6) contains supplementary material, which is available to authorized users.

Role of VEGF in metformin induced apoptosis of HepG2 cells

AIM

To investigate the molecular mechanism of metformin induced apoptosis of HepG2 cells.

METHODS

HepG2 cells were treated with different concentrations (0-20 mmol/L) of metformin (MET) for 24 h or 10 mmol/L MET for different times (0-48 h), and the effect of MET on cell proliferation was measured by MTT assay. Annexin V-FITC/PI flow cytometry was used to determine the apoptosis rate. RT-PCR was used to analyze the expression of vascular endothelial growth factor (VEGF) in HepG2 cells treated with MET.

RESULTS

MET had an obvious inhibitory effect on HepG2 cell proliferation. After treatment with 0, 5, 10, 15, and 20 mmol/L MET for 24 h, the relative cell viability rates of HepG2 cells were 100%, 80.56% ± 0.72%, 71.06% ± 0.70%, 64.73% ± 0.35%, and 54.73% ± 0.40%, respectively, showing a dose-dependent manner. After treatment with 10 mmol/L MET for 0, 12, 24, 36, and 48 h, the relative cell viability rates of HepG2 cells were 100%, 83.40% ± 0.70%, 69.86% ± 0.45%, 60.40% ± 0.88%, and 50.70% ± 0.45%, respectively, showing a time-dependent manner. Annexin V-FITC/PI flow cytometry revealed that the apoptosis rates of HepG2 cell were increased after treatment with 0, 5, 10, 15, and 20 mmol/L MET for 24 h, and the apoptosis rates were 2.78% ± 0.68%, 9.33% ± 0.22%, 17.13% ± 0.10%, 21.61% ± 0.20%, and 25.26% ± 1.09%, respectively, showing a dose-dependent manner. The apoptosis rates of HepG2 cells were increased after treatment with 10 mmol/L for 0, 12, 24, 36, 48 h, and the apoptosis rates were 2.05% ± 0.04%, 8.10% ± 0.08%, 16.53% ± 0.93%, 20.95% ± 0.16%, and 25.65% ± 0.44%, showing a time-dependent manner. The expression of VEGF decreased after treatment with different concentrations of MET for 24 h or 10 mmol/L MET for different times, showing a dose- and time-dependent manner.

CONCLUSION

MET can inhibit HepG2 cell proliferation via inducing apoptosis, which may involve the expression of VEGF.

Metformin Use Is Associated with Reduced Incidence and Improved Survival of Endometrial Cancer: A Meta-Analysis

Studies have suggested that metformin can potentially decrease the incidence of cancer and improve survival outcomes. However, the association between metformin use and the incidence and survival of endometrial cancer (EC) remains controversial. So, a meta-analysis was performed. An electronic search was conducted using PubMed, EMBASE, and Web of Science. The outcome measures were relative risks (RRs) or hazard ratios (HRs) with 95% confidence intervals (CIs) comparing the EC incidence and survival in patients treated with and without metformin. Eleven studies involving 766,926 participants were included in this study. In the pooled analysis of five studies which evaluated the association of metformin use with the incidence of EC, we found that metformin use was associated with a 13% reduction in EC risk among patients with diabetes (RR = 0.87, 95% CI: 0.80–0.95; p = 0.006). In the pooled analysis of six retrospective cohort studies evaluating the effect of metformin on the survival of EC patients, we found that, relative to nonuse, metformin use significantly improved the survival of EC patients (HR = 0.63, 95% CI: 0.45–0.87; p = 0.006). This study showed that metformin use was significantly associated with a decreased incidence of EC in diabetes and a favorable survival outcome of EC patients.