Metformin potentiates rapamycin and cisplatin in gastric cancer in mice

Metformin in combination with chemotherapy increases apoptosis in gastric cancer cells and counteracts senescence induced by chemotherapy

Gastric cancer (GC) is the fourth leading cause of cancer death in the world, and there is a demand for new therapeutic agents to treat GC. Metformin has been demonstrated to be an antineoplastic agent in some types of cancer; however, it has not been sufficiently valued in treating GC because the effect of metformin in combination with chemotherapy regimens has not yet been evaluated. The present study aimed to evaluate the mechanisms underlying cell death induced by metformin alone or when combined with chemotherapy. The cytogenetic characteristics of the NCI-N87 cell line were determined by fluorescence in situ hybridization (FISH). To determine viability, the cells were treated with metformin, epirubicin, cisplatin, docetaxel and 5-fluorouracil (individually and at different concentrations). Subsequently, the cells were treated with metformin alone, and in combination with the chemotherapeutic drugs and the epirubicin + cisplatin + 5-fluorouracil, docetaxel + cisplatin + 5-fluorouracil, and cisplatin + 5-fluorouracil regimens. Cell viability, proliferation and mitochondrial membrane potential (ΔΨm) were analyzed by spectrophotometry. Apoptosis, caspase activity and cell cycle progression were assessed by flow cytometry. Finally, light microscopy was used to evaluate senescence and clonogenicity. The results revealed that metformin, alone and when combined with chemotherapy, increased the proportion of apoptotic cells, promoted the loss of ΔΨm, and induced apoptosis through caspase activity in GC cells. Moreover, metformin decreased cell proliferation. In addition, metformin alone did not induce senescence and it counteracted the effects of chemotherapy-induced senescence in GC cells. Additionally, metformin, alone and when combined with chemotherapy, decreased the clonogenic capacity of NCI-N87 GC cells. In conclusion, metformin may increase the effects of chemotherapy on NCI-N87 cell death and could represent an option to improve the treatment of GC.

A comprehensive review on DCN1 protein, inhibitors and their therapeutic applications

DCN1, a critical co-E3 ligase in the neddylation process, mediates the activation of Cullin-RING Ligases (CRLs) by selectively catalyzing cullin neddylation, further regulating the activity of substrate proteins. It has been identified as an important target for human diseases, including cancers, fibrotic diseases, and cardiovascular disorders. This work aims to provide a perspective for the discovery of novel DCN1 inhibitors by the analysis of biological roles, protein structures, structure-activity relationships and design strategy disclosed in recent years. Additionally, we will discuss the current status, challenges and opportunities in hope of offering insights into the development of DCN1 inhibitors for human diseases.

DCUN1D1 and neddylation: Potential targets for cancer therapy

Cancer affects millions of people and understanding the molecular mechanisms related to disease development and progression is essential to manage the disease. Post-translational modification (PTM) processes such as ubiquitination and neddylation have a significant role in cancer development and progression by regulating protein stability, function, and interaction with other biomolecules. Both ubiquitination and neddylation are analogous processes that involves a series of enzymatic steps leading to the covalent attachment of ubiquitin or NEDD8 to target proteins. Neddylation modifies the CRL family of E3 ligase and regulates target proteins' function and stability. The DCUN1D1 protein is a regulator of protein neddylation and ubiquitination and acts promoting the neddylation of the cullin family components of E3-CRL complexes and is known to be upregulated in several types of cancers. In this review we compare the PTM ubiquitination and neddylation. Our discussion is focused on the neddylation process and the role of DCUN1D1 protein in cancer development. Furthermore, we provide describe DCUN1D1 protein and discuss its role in pathogenesis and signalling pathway in six different types of cancer. Additionally, we explore both the neddylation and DCUN1D1 pathways as potential druggable targets for therapeutic interventions. We focus our analysis on the development of compounds that target specifically neddylation or DCUN1D1. Finally, we provide a critical analysis about the challenges and perspectives in the field of DCUN1D1 and neddylation in cancer research. KEY POINTS: Neddylation is a post-translational modification that regulates target proteins' function and stability. One regulator of the neddylation process is a protein named DCUN1D1 and it is known to have its expression deregulated in several types of cancers. Here, we provide a detailed description of DCUN1D1 structure and its consequence for the development of cancer. We discuss both the neddylation and DCUN1D1 pathways as potential druggable targets for therapeutic interventions and provide a critical analysis about the challenges and perspectives in the field of DCUN1D1 and neddylation in cancer research.

Metformin: A Dual-Role Player in Cancer Treatment and Prevention

Cancer continues to pose a significant global health challenge, as evidenced by the increasing incidence rates and high mortality rates, despite the advancements made in chemotherapy. The emergence of chemoresistance further complicates the effectiveness of treatment. However, there is growing interest in the potential of metformin, a commonly prescribed drug for type 2 diabetes mellitus (T2DM), as an adjuvant chemotherapy agent in cancer treatment. Although the precise mechanism of action of metformin in cancer therapy is not fully understood, it has been found to have pleiotropic effects, including the modulation of metabolic pathways, reduction in inflammation, and the regulation of cellular proliferation. This comprehensive review examines the anticancer properties of metformin, drawing insights from various studies conducted in vitro and in vivo, as well as from clinical trials and observational research. This review discusses the mechanisms of action involving both insulin-dependent and independent pathways, shedding light on the potential of metformin as a therapeutic agent for different types of cancer. Despite promising findings, there are challenges that need to be addressed, such as conflicting outcomes in clinical trials, considerations regarding dosing, and the development of resistance. These challenges highlight the importance of further research to fully harness the therapeutic potential of metformin in cancer treatment. The aims of this review are to provide a contemporary understanding of the role of metformin in cancer therapy and identify areas for future exploration in the pursuit of effective anticancer strategies.

Diabetes Mellitus and Gastric Cancer: Correlation and Potential Mechanisms

This review summarizes the correlation between diabetes mellitus (DM) and gastric cancer (GC) from the perspectives of epidemiology, drug use, and potential mechanisms. The association between DM and GC is inconclusive, and the positive direction of the association reported in most published meta-analyses suggests that DM may be an independent risk factor for GC. Many clinical investigations have shown that people with DM and GC who undergo gastrectomy may have better glycemic control. The potential link between DM and GC may involve the interaction of multiple common risk factors, such as obesity, hyperglycemia and hyperinsulinemia, H. pylori infection, and the use of metformin. Although in vitro and in vivo data support that H. pylori infection status and metformin can influence GC risk in DM patients, there are conflicting results. Patient survival outcomes are influenced by multiple factors, so further research is needed to identify the patients who may benefit.

Rectifying disorder of extracellular matrix to suppress urethral stricture by protein nanofilm-controlled drug delivery from urinary catheter

Urethral stricture secondary to urethral injury, afflicting both patients and urologists, is initiated by excessive deposition of extracellular matrix in the submucosal and periurethral tissues. Although various anti-fibrotic drugs have been applied to urethral stricture by irrigation or submucosal injection, their clinical feasibility and effectiveness are limited. Here, to target the pathological state of the extracellular matrix, we design a protein-based nanofilm-controlled drug delivery system and assemble it on the catheter. This approach, which integrates excellent anti-biofilm properties with stable and controlled drug delivery for tens of days in one step, ensures optimal efficacy and negligible side effects while preventing biofilm-related infections. In a rabbit model of urethral injury, the anti-fibrotic catheter maintains extracellular matrix homeostasis by reducing fibroblast-derived collagen production and enhancing metalloproteinase 1-induced collagen degradation, resulting in a greater improvement in lumen stenosis than other topical therapies for urethral stricture prevention. Such facilely fabricated biocompatible coating with antibacterial contamination and sustained-drug-release functionality could not only benefit populations at high risk of urethral stricture but also serve as an advanced paradigm for a range of biomedical applications.

The Chemopreventive Role of β-Elemene in Cholangiocarcinoma by Restoring PCDH9 Expression

Background

β-Elemene, an effective anticancer component isolated from the Chinese herbal medicine Rhizoma Zedoariae, has been proved to have therapeutic potential against multiple cancers by extensive clinical trials and experimental research. However, its preventive role in cholangiocarcinoma (CCA) and the mechanisms of action of β-elemene on CCA need to be further investigated.

Methods

A thioacetamide (TAA)-induced pre-CCA animal model was well-established, and a low dosage of β-elemene was intragastrically (i.g.) administered for 6 months. Livers were harvested and examined histologically by a deep-learning convolutional neural network (CNN). cDNA array was used to analyze the genetic changes of CCA cells following β-elemene treatment. Immunohistochemical methods were applied to detect β-elemene-targeted protein PCDH9 in CCA specimens, and its predictive role was analyzed. β-Elemene treatment at the cellular or animal level was performed to test the effect of this traditional Chinese medicine on CCA cells.

Results

In the rat model of pre-CCA, the ratio of cholangiolar proliferation lesions was 0.98% ± 0.72% in the control group, significantly higher than that of the β-elemene (0. 47% ± 0.30%) groups (p = 0.0471). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the top 10 pathways affected by β-elemene treatment were associated with energy metabolism, and one was associated with the cell cycle. β-Elemene inactivated a number of oncogenes and restored the expression of multiple tumor suppressors. PCDH9 is a target of β-elemene and displays an important role in predicting tumor recurrence in CCA patients.

Conclusions

These findings proved that long-term use of β-elemene has the potential to interrupt the progression of CCA and improve the life quality of rats. Moreover, β-elemene exerted its anticancer potential partially by restoring the expression of PCDH9.

Combined regimens of cisplatin and metformin in cancer therapy: A systematic review and meta-analysis

INTRODUCTION

Cancer cell resistance to chemotherapy agents is a challenging issue in treating patients with cancer. Findings suggest that a combination of drugs may have synergistic or additive effects. in the present study, we systematically reviewed the combined regimens of metformin with cisplatin in various treating cancers.

METHODS

A comprehensive systematic search was performed in PubMed, Scopus, Embase, and other relevant databases with the following keyword "metformin", "cisplatin", "combination", "using all their equivalents and similar terms. Pooled odds ratio (OR) and 95% confidence intervals of cell viability and tumor volume as primary outcomes were calculated using Der-Simonian and Laird method while random effects meta-analysis was used, taking into account clinical and statistical heterogeneity.

RESULTS

Overall, 44 studies were retrieved, Findings of the present meta-analysis showed that combined regimens of metformin plus cisplatin was significantly associated with decreased odds of tumor volume and cell viability for all cancers compared with cisplatin alone (pooled OR: 0.40; 95% CI: 0.27, 0.58) and (pooled OR: 0.49; 95% CI: 0.42, 0.58) respectively. The result was same for cell viability in lung cancer (pooled OR: 0.59; 95% CI: 0.49, 0.70). The tumor size reduction and the response rate were evident in the animal xenografts model.

CONCLUSION

Findings indicated that combining metformin with cisplatin is a practical therapeutic approach to increase treatment efficacy in the case of cell viability and tumor volume and minimize side effects. A combination of metformin with cisplatin could enhance treatment efficacy through synergistic inhibitory effects on the growth of cancer cells.

Metformin for Cardiovascular Protection, Inflammatory Bowel Disease, Osteoporosis, Periodontitis, Polycystic Ovarian Syndrome, Neurodegeneration, Cancer, Inflammation and Senescence: What Is Next?

Diabetes is accompanied by several complications. Higher prevalence of cancers, cardiovascular diseases, chronic kidney disease (CKD), obesity, osteoporosis, and neurodegenerative diseases has been reported among patients with diabetes. Metformin is the oldest oral antidiabetic drug and can improve coexisting complications of diabetes. Clinical trials and observational studies uncovered that metformin can remarkably prevent or alleviate cardiovascular diseases, obesity, polycystic ovarian syndrome (PCOS), osteoporosis, cancer, periodontitis, neuronal damage and neurodegenerative diseases, inflammation, inflammatory bowel disease (IBD), tuberculosis, and COVID-19. In addition, metformin has been proposed as an antiaging agent. Numerous mechanisms were shown to be involved in the protective effects of metformin. Metformin activates the LKB1/AMPK pathway to interact with several intracellular signaling pathways and molecular mechanisms. The drug modifies the biologic function of NF-κB, PI3K/AKT/mTOR, SIRT1/PGC-1α, NLRP3, ERK, P38 MAPK, Wnt/β-catenin, Nrf2, JNK, and other major molecules in the intracellular signaling network. It also regulates the expression of noncoding RNAs. Thereby, metformin can regulate metabolism, growth, proliferation, inflammation, tumorigenesis, and senescence. Additionally, metformin modulates immune response, autophagy, mitophagy, endoplasmic reticulum (ER) stress, and apoptosis and exerts epigenetic effects. Furthermore, metformin protects against oxidative stress and genomic instability, preserves telomere length, and prevents stem cell exhaustion. In this review, the protective effects of metformin on each disease will be discussed using the results of recent meta-analyses, clinical trials, and observational studies. Thereafter, it will be meticulously explained how metformin reprograms intracellular signaling pathways and alters molecular and cellular interactions to modify the clinical presentations of several diseases.

Improved prognosis in gastric adenocarcinoma among metformin users in a population-based study

BACKGROUND

Metformin may improve the prognosis in gastric adenocarcinoma, but the existing literature is limited and contradictory.

METHODS

This was a Swedish population-based cohort study of diabetes patients who were diagnosed with gastric adenocarcinoma in 2005-2018 and followed up until December 2019. The data were retrieved from four national health data registries: Prescribed Drug Registry, Cancer Registry, Patient Registry and Cause of Death Registry. Associations between metformin use before the gastric adenocarcinoma diagnosis and the risk of disease-specific and all-cause mortality were assessed using multivariable Cox proportional hazard regression. The hazard ratios (HRs) and 95% confidence intervals (CIs) were adjusted for sex, age, calendar year, comorbidity, use of non-steroidal anti-inflammatory drugs or aspirin, and use of statins.

RESULTS

Compared with non-users, metformin users had a decreased risk of disease-specific mortality (HR 0.79, 95% CI 0.67-0.93) and all-cause mortality (HR 0.78, 95% CI 0.68-0.90). The associations were seemingly stronger among patients of female sex (HR 0.66, 95% CI 0.49-0.89), patients with tumour stage III or IV (HR 0.71, 95% CI 0.58-0.88), and those with the least comorbidity (HR 0.71, 95% CI 0.57-0.89).

CONCLUSIONS

Metformin use may improve survival in gastric adenocarcinoma among diabetes patients.

The Relationship between Diabetes Mellitus and Gastric Cancer and the Potential Benefits of Metformin: An Extensive Review of the Literature

The objective of this review is to summarize the findings of published research that investigated the relationship between diabetes mellitus and gastric cancer (GCa) and the potential benefits of metformin on GCa. Related literature has been extensively reviewed, and findings from studies investigating the relationship between diabetes mellitus and GCa suggest that hyperglycemia, hyperinsulinemia and insulin resistance are closely related to the development of GCa. Although not supported by all, most observational studies suggest an increased risk of GCa in patients with type 2 diabetes mellitus, especially in women and in Asian populations. Incidence of second primary malignancy diagnosed after GCa is significantly higher in diabetes patients. Diabetes patients with GCa may have more complications after gastrectomy or chemotherapy and they may have a poorer prognosis than patients with GCa but without diabetes mellitus. However, glycemic control may improve in the diabetes patients with GCa after receiving gastrectomy, especially after procedures that bypass the duodenum and proximal jejunum, such as Roux-en-Y gastric bypass or Billroth II reconstruction. The potential links between diabetes mellitus and GCa may involve the interactions with shared risk factors (e.g., obesity, hyperglycemia, hyperinsulinemia, insulin resistance, high salt intake, smoking, etc.), Helicobacter pylori (HP) infection, medications (e.g., insulin, metformin, statins, aspirin, proton pump inhibitors, antibiotics, etc.) and comorbidities (e.g., hypertension, dyslipidemia, vascular complications, heart failure, renal failure, etc.). With regards to the potential benefits of metformin on GCa, results of most observational studies suggest a reduced risk of GCa associated with metformin use in patients with T2DM, which can be supported by evidence derived from many in vitro and animal studies. Metformin use may also reduce the risk of HP infection, an important risk factor of GCa. In patients with GCa, metformin users may have improved survival and reduced recurrence. More studies are required to clarify the pathological subtypes/anatomical sites of GCa associated with type 2 diabetes mellitus or prevented by metformin, to confirm whether GCa risk can also be increased in patients with type 1 diabetes mellitus and to explore the possible role of gastric microbiota in the development of GCa.

Chemoprevention Against Gastric Cancer

Gastric cancer is the fifth most common cause of cancer and the third leading cause of cancer-related deaths globally. The number of gastric cancer-related deaths is only projected to increase, attributable primarily to the expanding aging population. Prevention is a mainstay of gastric cancer control programs, particularly in the absence of accurate, noninvasive modalities for screening and early detection, and the absence of an infrastructure for this purpose in the majority of countries worldwide. Herein, we discuss the evidence for several chemopreventive agents, along with putative mechanisms. There remains a clear, unmet need for primary chemoprevention trials for gastric cancer.

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 impairs cisplatin resistance effects in A549 lung cancer cells through mTOR signaling and other metabolic pathways

Lung cancer is the leading cause of cancer‑associated death worldwide and exhibits intrinsic and acquired therapeutic resistance to cisplatin (CIS). The present study investigated the role of mTOR signaling and other signaling pathways after metformin (MET) treatment in control and cisplatin‑resistant A549 cells, mapping pathways and possible targets involved in CIS sensitivity. MTT, flow cytometry, clonogenic assay, western blotting, proteomic analysis using the Stable Isotope Labeling by Amino acids in Cell culture (SILAC) approach and reverse transcription‑quantitative PCR were performed. The results revealed that CIS treatment induced mTOR signaling pathway overactivation, and the mTOR status was restored by MET. MET and the mTOR inhibitor rapamycin (RAPA) decreased the viability in control and resistant cells, and decreased the cell size increase induced by CIS. In control cells, MET and RAPA decreased colony formation after 72 h and decreased IC₅₀ values, potentiating the effects of CIS. Proteomics analysis revealed important pathways regulated by MET, including transcription, RNA processing and IL‑12‑mediated signaling. In CIS‑resistant cells, MET regulated the apoptotic process, oxidative stress and G₂/M transition. Annexin 4 (ANXA4) and superoxide dismutase 2 (SOD2), involved in apoptosis and oxidative stress, respectively, were chosen to validate the SILAC analysis and may represent potential therapeutic targets for lung cancer treatment. In conclusion, the chemosensitizing and antiproliferative effects of MET were associated with mTOR signaling and with potential novel targets, such as ANXA4 and SOD2, in human lung cancer cells.

The Chemosensitizing Role of Metformin in Anti-Cancer Therapy

Chemoresistance, which leads to the failure of chemotherapy and further tumor recurrence, presents the largest hurdle for the success of anti-cancer therapy. In recent years, metformin, a widely used first-line antidiabetic drug, has attracted increasing attention for its anti-cancer effects. A growing body of evidence indicates that metformin can sensitize tumor responses to different chemotherapeutic drugs, such as hormone modulating drugs, anti-metabolite drugs, antibiotics, and DNA-damaging drugs via selective targeting of Cancer Stem Cells (CSCs), improving the hypoxic microenvironment, and by suppressing tumor metastasis and inflammation. In addition, metformin may regulate metabolic programming, induce apoptosis, reverse Epithelial to Mesenchymal Transition (EMT), and Multidrug Resistance (MDR). In this review, we summarize the chemosensitization effects of metformin and focus primarily on its molecular mechanisms in enhancing the sensitivity of multiple chemotherapeutic drugs, through targeting of mTOR, ERK/P70S6K, NF-κB/HIF-1 α, and Mitogen- Activated Protein Kinase (MAPK) signaling pathways, as well as by down-regulating the expression of CSC genes and Pyruvate Kinase isoenzyme M2 (PKM2). Through a comprehensive understanding of the molecular mechanisms of chemosensitization provided in this review, the rationale for the use of metformin in clinical combination medications can be more systematically and thoroughly explored for wider adoption against numerous cancer types.>.

Metformin enhances anti-cancer effects of cisplatin in meningioma through AMPK-mTOR signaling pathways

Cisplatin is currently used to treat inoperable recurrent meningiomas, but its side effects and drug resistance limit its use. Metformin has recently been identified as a chemosensitizing agent. However, the combined treatment of cisplatin and metformin in high-grade meningiomas has not been reported. Herein, our findings demonstrate metformin significantly enhanced cisplatin-induced inhibition of proliferation in meningioma cells, which was associated with the induction of G0/G1 cell cycle arrest. Additionally, metformin activated adenosine monophosphate activated protein kinase (AMPK) and repressed the mammalian target of rapamycin (mTOR) signaling pathways via an AMPK-dependent mechanism. Furthermore, our xenograft murine model confirmed that metformin enhanced cisplatin’s anti-cancer effect by upregulation of AMPK and downregulation of mTOR signaling pathways. In addition, in 63 patients with atypical meningiomas, the activation of AMPK was significantly associated with tumor recurrence and short disease-free survival (DFS). These results demonstrate metformin enhanced the anti-cancer effect of cisplatin in meningioma in vitro and in vivo, an effect mediated through the activation of AMPK and repression of mTOR signaling pathways. Our study suggests the combined treatment of metformin and cisplatin is an effective and safe treatment for high-grade meningiomas.

Efficacy of Metformin and Chemotherapeutic Agents on the Inhibition of Colony Formation and Shh/Gli1 Pathway: Metformin/Docetaxel Versus Metformin/5-Fluorouracil

BACKGROUND

Gastric cancer is a common gastrointestinal cancer characterized by poor prognosis and chemoresistance. Docetaxel and 5-fluorouracil (5-FU) are frequently used for the treatment of gastric cancer. Despite their potent anti-cancer effects, chemoresistance occurs in metastatic gastric cancer. Metformin, a popular anti-diabetic drug, has been proven to have potent anticancer effects on gastrointestinal cancers. Here, we aim to improve this chemotherapy agents' efficacy by pretreatment with metformin.

METHODS

The AGS gastric cancer cell line were pretreated with three different sub-toxic concentration of metformin and then treated with various concentrations of 5-FU and docetaxel.The anticancer effects of the combination of metformin with the chemotherapy agents were determined using clonogenic assay and DAPi staining. We used real-time PCR to evaluate Gli1, Gli2, and TWIST1 mRNA expression levels in the gastric cancer cells. Also, the expression of the Shh protein was assessed using immunocytochemistry.

RESULTS

Here, we found that metformin sensitized the gastric cancer cells to chemotherapy. The combination treatments were more effective in reducing the number of cancer colonies compared to 5-FU or docetaxel alone. The combination of metformin with 5-FU or docetaxel significantly reduced the number of cells expressing the Shh protein compared to the 5-FU alone or docetaxel alone. Interestingly, we found that the combination of metformin with docetaxel significantly down-regulated the mRNA levels of Gli1, Gli2, and TWIST1 in the AGS gastric cancer cell line compared to docetaxel alone.

CONCLUSION

Overall, our data strongly support an important role for metformin as an enhancer of the efficacy of chemotherapeutic agents against gastric cancer.

Preventative and Therapeutic Effects of Metformin in Gastric Cancer: A New Contribution of an Old Friend

Gastric cancer (GC) is a cancer with high prevalence, and is one of the leading causes of cancer death worldwide. Metformin is a widely used hypoglycemic agent for type-2 diabetes mellitus (T2DM). Recently, metformin has drawn increasing attention in the field of cancer research for its emerging anti-cancer roles. However, the efficacy and underlying molecular mechanisms of metformin in the prevention and treatment for GC remain controversial. This review summarized the present clinical and mechanistic studies that investigated the efficacy of metformin in GC. It was found that the majority of clinical studies affirmed protective roles of metformin in both gastric cancer risk and survival rate. In addition, metformin’s effects in the prevention and treatment for GC involve multiple pathways mainly via AMPK and IGF-1R. It was concluded that metformin presents a unique opportunity for application against GC, but further clinical and mechanistic investigations are required to solidify the roles of metformin in GC.

Metformin Restores the Drug Sensitivity of MCF-7 Cells Resistant Derivates via the Cooperative Modulation of Growth and Apoptotic-Related Pathways

The phenomenon of the primary or acquired resistance of cancer cells to antitumor drugs is among the key problems of oncology. For breast cancer, the phenomenon of the resistance to hormonal or target therapy may be based on the numerous mechanisms including the loss or mutation of estrogen receptor, alterations of antiapoptotic pathways, overexpression of growth-related signaling proteins, etc. The perspective approaches for overcoming the resistance may be based on the usage of compounds such as inhibitors of the cell energetic metabolism. Among the latter, the antidiabetic drug metformin exerts antitumor activity via the activation of AMPK and the subsequent inhibition of mTOR signaling. The experiments were performed on the ERα-positive MCF-7 breast cancer cells, the MCF-7 sublines resistant to tamoxifen (MCF-7/T) and rapamycin (MCF-7/Rap), and on triple-negative MDA-MB-231 breast cancer cells. We have demonstrated metformin’s ability to enhance the cytostatic activity of the tamoxifen and rapamycin on both parent MCF-7 cells and MCF-7-resistant derivates mediated via the suppression of mTOR signaling and growth-related transcriptional factors. The cooperative effect of metformin and tested drugs was realized in an estrogen-independent manner, and, in the case of tamoxifen, was associated with the activation of apoptotic cell death. Similarly, the stimulation of apoptosis under metformin/tamoxifen co-treatment was shown to occur in the MCF-7 cells after steroid depletion as well as in the ERα-negative MDA-MB-231 cells. We conclude that metformin co-treatment may be used for the increase and partial restoration of the cancer cell sensitivity to hormonal and target drugs. Moreover, the combination of metformin with tamoxifen induces the apoptotic death in the ERα-negative breast cancer cells opening the additional perspectives in the treatment of estrogen-independent breast tumors.

Impact of Metformin Use on Survival in Patients with Gastric Cancer and Diabetes Mellitus Following Gastrectomy

Studies have shown the anticancer effects of metformin in vitro. However, whether metformin can prevent cancer recurrence or prolong survival in patients with gastric cancer (GC) and diabetes mellitus (DM) post-gastrectomy remains unknown. We evaluated the beneficial effects of metformin in patients with GC and DM post-gastrectomy. We recruited 2400 patients with GC (1749 without DM, 651 with DM) who underwent surgery between 1997 and 2010. Patients with DM were stratified into metformin (group 1) and non-metformin (group 2) users. Their clinicopathological data were recorded prospectively, and demographics, recurrence-free survival (RFS), and cancer-specific survival (CSS) were compared. Tumour recurrence risk and cause of death were analysed between groups 1 and 2 among patients with DM stratified by tumour stage. We also compared RFS and overall survival among patients with and without DM. Tumour recurrence occurred in 201 patients with GC: 57 (25%) in group 1 and 144 (37%) in group 2. After adjusting for confounders, metformin significantly prolonged CSS (hazard ratio (HR) = 0.54, 95% confidence interval (CI) = 0.38-0.77) in patients with stage I-III GC and DM. In subgroup analysis, metformin users with stage III GC and DM had significantly prolonged CSS compared to non-metformin users (HR = 0.45, 95% CI = 0.30-0.68), with an insignificant difference in patients with stage I-II GC. Adjusted HRs for RFS and CSS were significantly lower in patients with stage I-III GC and DM than those in patients without DM (0.67 (95% CI = 0.54-0.92) and 0.62 (95% CI = 0.50-0.77), respectively), with an insignificant difference in patients with stage I GC. Metformin significantly reduces tumour recurrence risk and improves CSS in patients with stage III GC and DM post-gastrectomy. Further prospective studies may confirm the efficacy of metformin as an adjunctive treatment for advanced GC postoperatively.

Metformin sensitizes therapeutic agents and improves outcome in pre-clinical and clinical diffuse large B-cell lymphoma

BACKGROUND

The treatment of diffuse large B-cell lymphoma (DLBCL) is limited by the development of resistance to therapy, and there is a need to develop novel therapeutic strategies for relapsed and refractory aggressive lymphoma. Metformin is an oral agent for type 2 diabetes that has been shown to decrease cancer risk and lower mortality in other types of cancer.

METHODS

We performed a retrospective analysis of the RPCCC database looking at patients with DLBCL treated with front-line chemotherapy. We also performed pre-clinical studies looking at the effect of metformin on cell viability, cell number, Ki67, ATP production, apoptosis, ROS production, mitochondrial membrane potential, cell cycle, effect with chemotherapeutic agents, and rituximab. Finally, we studied mouse models to see the anti-tumor effect of metformin.

RESULTS

Among diabetic patients, metformin use was associated with improved progression-free survival (PFS) and overall survival (OS) compared to diabetic patients not on metformin. Our pre-clinical studies showed metformin is itself capable of anti-tumor effects and causes cell cycle arrest in the G1 phase. Metformin induces apoptosis, ROS production, and increased mitochondrial membrane permeability. Metformin exhibited additive/synergistic effects when combined with traditional chemotherapy or rituximab in vitro. In vivo, metformin in combination with rituximab showed improved survival compared with rituximab monotherapy.

CONCLUSIONS

Our retrospective analysis showed that metformin with front-line chemotherapy in diabetic patients resulted in improved PFS and OS. Our pre-clinical studies demonstrate metformin has potential to re-sensitize resistant lymphoma to the chemo-immunotherapy and allow us to develop a hypothesis as to its activity in DLBCL.

Identification of MicroRNA-Target Gene-Transcription Factor Regulatory Networks in Colorectal Adenoma Using Microarray Expression Data

Objective

The aim of the study was to find the key genes, microRNAs (miRNAs) and transcription factors (TFs) and construct miRNA-target gene-TF regulatory networks to investigate the underlying molecular mechanism in colorectal adenoma (CRA).

Methods

Four mRNA expression datasets and one miRNA expression dataset were downloaded from Gene Expression Omnibus (GEO) database. Differentially expressed miRNAs (DEMs) and differentially expressed genes (DEGs) were identified between CRA and normal samples. Moreover, functional enrichment analysis for DEGs was carried out utilizing the Cytoscape-plugin, known as ClueGO. These DEGs were mapped to STRING database to construct a protein-protein interaction (PPI) network. Then, a miRNA-target gene regulatory network was established to screen key DEMs. In addition, similar workflow of the analyses were also performed comparing the CRC samples with CRA ones to screen key DEMs. Finally, miRNA-target gene-TF regulatory networks were constructed for these key DEMs using iRegulon plug-in in Cytoscape.

Results

We identified 514 DEGs and 167 DEMs in CRA samples compared to healthy samples. Functional enrichment analysis revealed that these DEGs were significantly enriched in several terms and pathways, such as regulation of cell migration and bile secretion pathway. A PPI network was constructed including 325 nodes as well as 890 edges. A total of 59 DEGs and 65 DEMs were identified in CRC samples compared to CRA ones. In addition, Two key DEMs in CRA samples compared to healthy samples were identified, such as hsa-miR-34a and hsa-miR-96. One key DEM, hsa-miR-29c, which was identified when we compared the differentially expressed molecules found in the comparison CRA versus normal samples to the ones obtained in the comparison CRC versus CRA, was also identified in CRC samples compared to CRA ones. The miRNA-target gene-TF regulatory networks for these key miRNAs included two TFs, one TF and five TFs, respectively.

Conclusion

These identified key genes, miRNA, TFs and miRNA-target gene-TF regulatory networks associated with CRA, to a certain degree, may provide some hints to enable us to better understand the underlying pathogenesis of CRA.

The effect of metformin on gastric cancer in patients with type 2 diabetes: a systematic review and meta-analysis

BACKGROUND

Metformin, a drug widely used in the treatment of diabetes, has proven preventive and survival benefits for various malignancies. However, the effect of metformin on gastric cancer risk and survival rate in T2DM patients remains controversial. Therefore, we conducted a systematic review and meta-analysis to evaluate the effect of metformin on gastric cancer in T2DM patients.

METHODS

We searched PubMed, EMBASE, Medline and the Cochrane Library for related studies up to October 22, 2019. Pooled hazard ratios with 95% confidence intervals were calculated using random-effects model. Heterogeneity was assessed. All articles were evaluated by Newcastle-Ottawa Scale.

RESULTS

A total of 11 cohort studies met eligibility criteria and were included in the meta-analysis. The use of metformin was related to a significant 21% reduction in GC incidence (HR 0.790; 95% CI 0.624-1.001). Subgroup analysis showed that the use of metformin significantly reduced the risk of gastric cancer in T2DM patients in Asian populations, but not in western populations. In a pooled analysis of 3 studies, metformin use was associated with increased overall survival rate (HR 0.817; 95% CI 0.600-1.113) and cancer-specific survival rate (HR 0.824; 95% CI 0.614-1.106) of T2DM patients.

CONCLUSIONS

Metformin could reduce the risk of gastric cancer in T2DM patients, particularly in Asian populations. However, it is debatable whether metformin use can improve the prognosis of gastric cancer in T2DM patients.

Metformin use and risk of gastric adenocarcinoma in a Swedish population-based cohort study

Background

Whether or not the use of metformin decreases the risk of gastric adenocarcinoma is unclear.

Methods

This was a population-based cohort study in 2005–2015. Associations between metformin use and gastric non-cardia and cardia adenocarcinomas were examined within two cohorts; a diabetes cohort of participants using anti-diabetes medications, and a matched cohort of common-medication users, where metformin non-users were frequency matched (10:1) with metformin users for sex and age. Multivariable Cox proportional hazard regression analyses provided hazard ratios (HR) and 95% confidence intervals (CI), adjusting for sex, age, calendar year, comorbidity, Helicobacter pylori eradication treatment, use of non-steroidal anti-inflammatory drugs or aspirin and use of statins.

Results

During the follow-up for a median of 5.8 years, 892 (0.1%) participants in the diabetes cohort and 6395 (0.1%) participants in the matched cohort of common-medication users developed gastric adenocarcinoma. Metformin users had no significantly decreased risk of gastric non-cardia adenocarcinoma (diabetes cohort: HR 0.93, 95% CI 0.78–1.12; matched cohort: HR 1.30, 95% CI 1.18–1.42) or cardia adenocarcinoma (diabetes cohort: HR 1.49, 95% CI 1.09–2.02; matched cohort: HR 1.58, 95% CI 1.38–1.81) compared with non-users in both cohorts.

Conclusions

This cohort study with <10 years of follow-up suggests metformin use may not prevent gastric adenocarcinoma.

CDX1 Expression Induced by CagA-Expressing Helicobacter pylori Promotes Gastric Tumorigenesis

Intestinal-type gastric cancer often results from Helicobacter pylori infection through intestinal metaplasia, a transdifferentiated premalignant phenotype. Because H. pylori virulence factor CagA has been associated with aberrant expression of the transcription factor CDX1, which regulates intestinal differentiation, we explored its relationship with H. pylori infection and function during gastric carcinogenesis in normal gastric epithelial cells and gastric cancer cell lines. Infection of HFE 145 cells with CagA⁺ H. pylori increased expression of CDX1, as well as the epithelial-to-mesenchymal transition (EMT) markers Snail and Slug, increased invasion and migration, but those effects were not found in HFE 145 cells infected with CagA-deficient H. pylori. CDX1 overexpression increased expression of the intestinal markers Villin, sucrose isomaltase (SI), and MUC2, induced spheroid formation, and enhanced expression of the stem cell markers CD44, SOX2, Oct4, and Nanog, while CDX1 knockdown inhibited proliferation and intestinal stemness. Treatment of CDX1-expressing cells with metformin, an antidiabetic drug known to decrease the risk of gastric cancer, decreased expression of EMT and stemness markers, and reduced spheroid formation. In a murine xenograft model, combining metformin or shCDX1 with cisplatin reduced tumor growth, increased caspase-3 cleavage, and reduced expression of CD44 and MMP-9 to a greater degree than cisplatin alone. Patients with more advanced intestinal metaplasia staging exhibited higher CDX1 expression than those with earlier intestinal metaplasia staging (P = 0.039), and those with H. pylori tended to have more CDX1 expression than noninfected patients (P = 0.061). Finally, human tissue samples with higher CDX1 levels showed prominent CD44/SOX2 expression. Our findings indicate CagA⁺ H. pylori-induced CDX1 expression may enhance gastric cancer tumorigenesis and progression, and support therapeutic targeting of CDX1 in gastric cancer. IMPLICATIONS: This study shows that CDX1 contributes to the tumorigenesis and progression of gastric cancer and suggests the potential of targeting CDX1 to treat this malignancy.

The therapeutic potential of metformin in gastric cancer

Metformin is a biguanide molecule used since 1957 to treat type 2 diabetes patients. In addition to its hypoglycemic effects, epidemiological studies have shown that metformin can be associated with a decrease in cancer development risk in diabetic populations. Thus, since 2005 this molecule is largely studied for its antitumoural properties in different types of cancer. The potential antitumoural effect of metformin in gastric cancer has been poorly studied. Here, we detailed the different described mechanisms implicated in the antitumoural effect of metformin in gastric cancer, from the signalling pathways to the functional effects on gastric cancer cell lines and gastric cancer stem cells.

[6]-Gingerol enhances the cisplatin sensitivity of gastric cancer cells through inhibition of proliferation and invasion via PI3K/AKT signaling pathway

Cisplatin-based chemotherapy is a widely used chemotherapeutic regimen for gastric cancer; however, drug resistance limits its efficacy. [6]-Gingerol has been found to exhibit anticancer effects. Here, we aim to explore the potential of [6]-gingerol in combination with cisplatin as a new regimen for gastric cancer. CCK-8 assay and colony formation assay were used to determine the effect of [6]-gingerol in combination with cisplatin on cell viability of gastric cancer cells. Flow cytometry was performed to assess cell cycle distribution. Wound-healing assay and transwell invasion assay were conducted to examine the migration and invasion abilities. Cell cycle and invasion-related proteins and mRNAs, as well as PI3K/AKT signaling proteins, were assessed by western blotting and quantitative real-time polymerase chain reaction. Combination of [6]-gingerol with cisplatin inhibited cell viability and enhanced cell cycle arrest at G1 phase compared with cisplatin alone. The combination treatment inhibited cell migration and invasion ability and decreased cyclin D1, cyclin A2, matrix metalloproteinase-9, p-PI3K, AKT, and p-AKT protein expressions and increased P21 and P27 mRNA levels. Our study demonstrates that [6]-gingerol enhances the cisplatin sensitivity of gastric cancer cells and that the mechanisms involve G1 phase arrest, migration and invasion suppression via PI3K/AKT signaling pathway.

Avasimibe inhibits tumor growth by targeting FoxM1-AKR1C1 in osteosarcoma

Background

Osteosarcoma (OS) is a rare bone tumor with a high propensity for lung metastasis and poor patient outcomes. It is crucial to identify novel therapeutic strategies and biomarkers.

Patients and methods

ARK1C1 staining was detected in OS specimens, and its clinical significance was assessed. A potential AKR1C1 inhibitor, avasimibe, was used to target AKR1C1.

Results

High expression of AKR1C1 was observed in OS and was associated with poor outcomes for patients with OS. Avasimibe was found to inhibit cell proliferation and tumor growth by reducing the expression of AKR1C1 and FoxM1 in vivo and in vitro.

Conclusion

These findings indicate that AKR1C1 is a promising prognostic factor and may serve as a novel therapeutic target of avasimibe for human OS.

Metformin sensitizes cholangiocarcinoma cell to cisplatin-induced cytotoxicity through oxidative stress mediated mitochondrial pathway

AIMS

Metformin (Met), an essential antidiabetic agent, shows antitumor activity in some cancers. A previous study showed that Met enhanced cytotoxic activity of cisplatin (Cis) in cholangiocarcinoma (CCA) in association with the activation of AMP-activated protein kinase and suppression of Akt-mTOR. However, these effects do not entirely explain the observed chemosensitizing effect. The present study investigated the interaction of Met and Cis over the enhanced antitumor effect.

MAIN METHODS

KKU-100 and KKU-M156 cells were used in the study. Cytotoxicity was assessed by acridine orange-ethidium bromide staining. Reactive oxygen species (ROS) and mitochondrial transmembrane potential (Δψ_m) were measured by dihydroethidium and JC-1 fluorescent methods. Cellular glutathione (GSH) and redox ratio were analyzed by enzymatic coupling assay. Proteins associated with antioxidant system and cell death were evaluated by western immunoblot.

KEY FINDINGS

Cytotoxicity of Cis was enhanced by Met in association with ROS formation and GSH redox stress. The antioxidants, N-acetylcysteine and TEMPOL, and MPTP inhibitor, cyclosporine, attenuated cytotoxicity in association with suppression of ROS formation and the losses of Δψ_m. Met in combination with Cis suppressed expression of Nrf2 and altered the expression of Bcl2 family proteins.

SIGNIFICANCE

The chemosensitizing effect of Met in combination with Cis is causally associated with increased oxidative stress-mediated mitochondrial cell death pathway. Met may improve the efficacy of Cis in the treatment of cancer.

Metformin inhibits ovarian cancer growth and migration in vitro and in vivo by enhancing cisplatin cytotoxicity

The purpose of the current study was to investigate whether metformin can enhance the anti-cancer effect of cisplatin on epithelial ovarian cancer in vitro and in vivo. CCK-8 assays were performed to detect cell viability, and flow cytometry was performed to measure cell apoptosis rates. Transwell assays were used to detect the migration and invasion ability of ovarian cancer cells. Western blotting and qRT-PCR were performed to detect protein expression. Xenograft mouse models were constructed to clarify the treatment response in vivo. Metformin alone or cisplatin alone dose-dependently inhibited SKOV3 and Hey cell proliferation. The combination of these two drugs exerted a stronger inhibitory effect with a higher apoptosis rate than administration of either drug alone. Transwell assay results revealed that metformin promoted the inhibitory effect of cisplatin on ovarian cancer cell metastasis. Metformin and cisplatin co-treatment significantly inhibited N-cadherin and MMP-9 expression. The Western blotting results revealed that metformin and cisplatin co-treatment inhibited TGFβ1 expression and Smad2 and Smad3 phosphorylation. The in vivo study results were consistent with results from the in vitro study. Data from our study suggest that metformin enhanced the anti-tumour effect of cisplatin on epithelial ovarian cancer in vitro and in vivo, which provides more evidence supporting the use of metformin to treat epithelial ovarian cancer.

Long noncoding RNA H19 participates in metformin-mediated inhibition of gastric cancer cell invasion

Recent research suggests that the first-line oral antidiabetes drug metformin may prevent gastric cancer progression and improve prognosis. Many studies have also shown that long noncoding RNAs (lncRNAs) play important roles in many biological processes. Therefore, we aimed to explore whether lncRNAs participate in the mechanisms by which metformin affects gastric cancer cells. In the current study, we found that metformin significantly inhibited the cellular functions of gastric cancer cells through Cell Counting Kit-8 and invasion assays. We found that lncRNA H19 was greatly downregulated in gastric cancer cells treated with metformin using lncRNA microassays. Based on bioinformatics analyses of the Oncomine and The Cancer Genome Atlas databases, H19 is shown to be overexpressed in gastric cancer tissues, with increased expression of H19 relating to advanced pathological tumor stage and pathological tumor node metastasis stage, indicating that H19 may be associated with the invasive ability of gastric cancer. We knocked down H19 in AGS and SGC7901 cell lines and found that knocked-down H19 could decrease gastric cancer cell invasion and that metformin could not further decrease invasion after the knock down. Moreover, H19 depletion increased AMPK activation and decreased MMP9 expression, and metformin could not further activate AMPK or decrease MMP9 in H19 knocked-down gastric cancer cells. In summary, metformin has a profound antitumor effect on gastric cancer cells, and H19 is a key component in the process of metformin suppressing gastric cancer cell invasion.

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.

Co-delivery of Metformin and Paclitaxel Via Folate-Modified pH-Sensitive Micelles for Enhanced Anti-tumor Efficacy

Single chemotherapeutic agent like paclitaxel (PTX) has shown some limitations in anti-tumor treatment, such as undesirable side effects, multidrug resistance, and high toxicity. In order to reduce the toxicity of PTX and increase the anti-tumor effect, folate-modified amphiphilic and biodegradable biomaterial was developed to co-deliver PTX and metformin (MET) for exerting the synergistic effect. PTX was physically entrapped in the hydrophobic inner core of the amphiphilic block copolymer by a solvent evaporation method, whereas MET was chemically conjugated to the hydrophilic terminals of copolymer via a pH-sensitive cis-aconityl linkage (Cis). The in vitro release behaviors of the drugs were analyzed by high-performance liquid chromatography (HPLC), and the synergistic effect of the drugs was evaluated by a Q value method. Results showed that drug-loaded micelles with an average size about 100 nm were successfully constructed. In acidic environments, the chemically conjugated MET was rapidly released after the breakage of sensitive bond between drug and copolymer. In vitro anti-tumor studies demonstrated that MET and PTX had a synergistic effect and co-delivery micelles induced higher cytotoxicity and apoptosis against 4T1 breast cancer cells than free drugs. Furthermore, folate-targeted co-delivery micelles increased the cellular uptake of drugs and were found to be effective for the treatment of solid tumor in vivo. These findings indicated that co-delivery of MET and PTX through the polymeric micelles is a promising strategy for cancer therapy.

Metformin sensitizes endometrial cancer cells to chemotherapy through IDH1-induced Nrf2 expression via an epigenetic mechanism

Chemoresistance is the major obstacle to cure endometrial cancer, whereas metformin has demonstrated sensitization to chemotherapy in endometrial cancer. A novel finding states that isocitrate dehydrogenase 1 (IDH1) involves in cancer chemoresistance. Recent studies have revealed that epigenetic modifications facilitate chemoresistance. However, whether IDH1 play a role in metformin-induced endometrial cancer chemosensitivity through epigenetic modification is incompletely understood. Immunohistochemistry and Elisa assays were used to evaluate the expression pattern of IDH1 in endometrial tissue and serum, respectively. Western blot was performed to determine changes in expression of key molecules in the IDH1-ɑ-KG-TET1-Nrf2 signaling pathway after various treatments. Dot blot assays were used to assess global hydroxymethylation levels after metformin administration or plasmid transfection. Antioxidant response element (ARE) activity in the IDH1 promoter region was monitored by luciferase assay. Cancer cell sensitivity to chemotherapy was detected by SRB assay. We found that activation of the IDH1 signaling pathway in endometrial cancer tissue resulting from aberrant expression of IDH1 and its downstream mediators conferred chemoresistance. We found that this effect was abated by metformin treatment. Dot blot and HMeDIP assays revealed that metformin blocked IDH1-ɑ-KG-TET1-mediated enhancement of Nrf2 hydroxymethylation levels, eliminating chemoresistance. Moreover, we observed that chemoresistance was enhanced via a regulatory loop in which Nrf2 activated IDH1-ɑ-KG-TET1-Nrf2 signaling via binding to the ARE sites in the IDH1 promoter region. Our findings highlight a critical role of IDH1-ɑ-KG-TET1-Nrf2 signaling in chemoresistance and suggest that rational combination therapy with metformin and chemotherapeutics has the potential to suppress chemoresistance.

From rapalogs to anti-aging formula

Inhibitors of mTOR, including clinically available rapalogs such as rapamycin (Sirolimus) and Everolimus, are gerosuppressants, which suppress cellular senescence. Rapamycin slows aging and extends life span in a variety of species from worm to mammals. Rapalogs can prevent age-related diseases, including cancer, atherosclerosis, obesity, neurodegeneration and retinopathy and potentially rejuvenate stem cells, immunity and metabolism. Here, I further suggest how rapamycin can be combined with metformin, inhibitors of angiotensin II signaling (Losartan, Lisinopril), statins (simvastatin, atorvastatin), propranolol, aspirin and a PDE5 inhibitor. Rational combinations of these drugs with physical exercise and an anti-aging diet (Koschei formula) can maximize their anti-aging effects and decrease side effects.

Metformin potentiates anti-tumor effect of resveratrol on pancreatic cancer by down-regulation of VEGF-B signaling pathway

Our previous study showed that resveratrol (RSV) exhibited not only anti-tumor effect, but also had potential tumor promotion effect on pancreatic cancer (Paca) cells through up-regulation of VEGF-B. We determined whether metformin (MET) could potentiate the anti-tumor effect of RSV on PaCa in this study. Combination of RSV (100 μmol/l) and MET (20 mmol/l) significantly inhibited tumor growth and increased apoptosis of human PaCa in comparison with RSV or MET alone treatment in PaCa cell lines (Miapaca-2, Panc-1 and Capan-2). Combination of RSV (60 mg/kg, gavage) and MET (250 mg/kg, i.p.) significantly inhibited tumor growth in PaCa bearing nude mice (subcutaneous injection of 5 × 10⁶ Miapaca-2 cells) in comparison with RSV or MET alone treatment on day 40. Combination treatment significantly decreased VEGF-B expression and inhibited activity of GSK-3β when compared to the RSV alone treatment. Up-regulated expressions of Bax, cleaved caspase-3 and down-regulated expression of Bcl-2 were observed in RSV+ MET group in comparison with RSV group either in vitro or in vivo. Inhibition of VEGF-B by VEGF-B small interfering RNA (siRNA) mimicked the effects of MET on PaCa cells. These results suggested that MET, a potential pharmacological inhibitor of VEGF-B signaling pathway, potentiated the anti-tumor effect of RSV on PaCa, and combination of MET and RSV would be a promising modality for clinical PaCa therapy.

Impact of metformin on gastric adenocarcinoma survival: A Belgian population based study

BACKGROUND

Preclinical studies have shown anticancer activities of metformin in gastric cancer and a recent epidemiological study showed a decrease in recurrence and mortality of gastric cancer in metformin users. This study aimed to assess the impact of metformin on gastric cancer survival in diabetic patients at a Belgian population level.

METHODS

We conducted an observational, population-based study by linking data of the Belgian Cancer Registry with medical claims data coming from the health insurance companies for patients diagnosed with stage I to III gastric adenocarcinoma between 2006 and 2012. Information on gastric cancer-specific deaths was retrieved from mortality records collected by regional governments. Time-dependent Cox regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CI) for overall survival (OS) and cancer-specific mortality (CSS).

RESULTS

In our population of 371 patients, a reduction in all-cause mortality was observed in metformin users (adjusted HR = 0.73, 95% CI: [0.52; 1.01], p = 0.06) but not for cancer specific mortality (adjusted HR = 0.86, 95% CI: [0.56; 1.33], p = 0.50). Pre-diagnosis exposure to metformin was associated with a significant improvement in OS (adjusted HR = 0.75, 95% CI: [0.57; 0.98], p = 0.04) that was not significant for CSS (adjusted HR = 0.89, 95% CI: [0.62; 1.28], p = 0.52). Moreover, no dose-response relationship between metformin use and either all-cause or cancer-specific mortality was observed.

CONCLUSION

In the first population based study of metformin use in gastric cancer adenocarcinoma patients with previous diabetes, our findings suggest that metformin use might improve overall mortality. However, no such association was found for cancer-specific survival. Additional studies in other populations are required.

Metformin use and cervical cancer risk in female patients with type 2 diabetes

This study evaluated whether metformin may affect the risk of cervical cancer. The reimbursement databases of the Taiwan's National Health Insurance were used. Female patients with type 2 diabetes at an onset age of 25-74 years during 1999-2005 and newly treated with metformin (n=132971, "ever users of metformin") or other antidiabetic drugs (n=6940, "never users of metformin") were followed for at least 6 months until December 31, 2011. The treatment effect of metformin (for ever versus never users, and for tertiles of cumulative duration of therapy) was estimated by Cox regression incorporated with the inverse probability of treatment weighting using propensity score. Analyses were also conducted in a 1:1 matched pair cohort based on 8 digits of propensity score. Results showed that the respective numbers of incident cervical cancer in ever users and never users were 438 (0.33%) and 38 (0.55%), with respective incidences of 68.29 and 121.38 per 100,000 person-years. The overall hazard ratio suggested a significantly lower risk in metformin users (0.558, 95% confidence intervals: 0.401-0.778). In tertile analyses, the hazard ratios (95% confidence intervals) for the first (<23.0 months), second (23.0-47.9 months) and third (>47.9 months) tertile of cumulative duration were 1.272 (0.904-1.790), 0.523 (0.366-0.747) and 0.109 (0.070-0.172), respectively. Findings were supported by the analyses in the matched cohort. In conclusion, metformin may significantly reduce the risk of cervical cancer, especially when the cumulative duration is more than 2 years.

Metformin use and its effect on gastric cancer in patients with type 2 diabetes: A systematic review of observational studies

Increasing evidence suggests that metformin use is associated with a decreased risk of cancer. The traditional therapies for gastric cancer (GC) are gastrectomy and chemoradiotherapy; however, these therapies may cause certain adverse effects, which affect a patient's quality of life, and the overall survival rate is low. At present, little is known about whether the use of metformin decreases the risk of GC in patients with type 2 diabetes. Therefore, in the present study, a systematic review was performed to analyze the effect of metformin on GC. A literature search was conducted in PubMed, EMBASE, and the Cochrane Library databases for articles published up to June 30th, 2016. The studies that evaluated GC patients treated with metformin and compared them with GC patients treated with other antidiabetic drugs were reviewed. Eligible studies were evaluated using the Newcastle-Ottawa Scale. Adjusted hazard ratio and 95% confidence intervals were determined to evaluate the effect of metformin on GC. From the 422 articles evaluated, 5 studies involving a total of 1,804,479 patients met the inclusion criteria and were qualitatively analyzed. The quality of all selected articles was classified as moderate. These studies reported that the long-term use of metformin was associated with a lower risk of GC compared with the lack of use of metformin or the use of other hypoglycemic drugs. In GC patients with diabetes who were subjected to gastrectomy, the cumulative use of metformin reduced the rates of disease recurrence and of all-cause and cancer-specific mortality. Despite the limited number of studies on this subject, currently available evidence indicates that metformin is associated with a decreased risk of GC and improves survival in patients with type 2 diabetes. However, more well-designed trials are required to elucidate this association.

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.

Metformin enhances the chemosensitivity of hepatocarcinoma cells to cisplatin through AMPK pathway

This study investigated the effect of metformin on chemosensitivity of hepatocarcinoma cells to cisplatin and the possible mechanism. HepG2 and Huh-7 hepatoma cells were treated with cisplatin at concentrations of 0, 2, 4, 6, 8 and 10 µM for 48 h. Proliferation of HepG2 and Huh-7 hepatoma cells were detected by MTT assay. Apoptosis of hepatocellular carcinoma cells was detected by flow cytometry. Western blot analysis was used to detect the expression of 5-monophosphate-activated protein kinase (AMPK) and p-AMPK protein. Proliferative activity of HepG2 and Huh-7 cells decreased with the increase of cisplatin concentration. After adding metformin, proliferation ability of hepatocarcinoma cells was significantly reduced. Apoptosis rate of the metformin was significantly higher than that of the control group, and apoptosis rate of the cisplatin + metformin was significantly higher than that of the cisplatin group. There was no significant difference in expression level of AMPK protein found between control, metformin, cisplatin and cisplatin + metformin group. Compared with the control, ratio of p-AMPK/AMPK in metformin group was increased, and ratio of p-AMPK/AMPK in cisplatin + metformin was significantly higher than that in cisplatin group. Activity of cells in cisplatin + metformin + compound C (AMPK pathway blocker) group was significantly higher than that of cisplatin + metformin, while apoptosis of cells in cisplatin + metformin + compound C (AMPK pathway blocker) was significantly lower than that of cisplatin + metformin group. In conclusion, metformin can inhibit the proliferation, promote apoptosis and enhance the chemosensitivity of hepatocarcinoma cells to cisplatin through AMPK pathway.

Redox-dependent modulation of metformin contributes to enhanced sensitivity of esophageal squamous cell carcinoma to cisplatin

Glutathione is the major intracellular anti-oxidant against reactive oxygen species and serves as a detoxification essential. The anti-diabetic drug metformin has been showed to exert anti-tumor activity via modulation of redox homeostasis. In this study, we provided evidence that metformin inhibits proliferation and induces apoptosis of esophageal squamous cancer cells. Importantly, we found that metformin acts as pro-oxidant via depletion of intracellular glutathione. Co-treatment with metformin reversed the elevated intracellular glutathione induced by cisplatin and therefore enhanced the sensitivity to cisplatin in vitro and in vivo. Taken together, our data indicate that combination of metformin with cisplatin may represent a novel therapeutic strategy for esophageal squamous cell carcinoma treatment.

Study protocol of a phase IB/II clinical trial of metformin and chloroquine in patients with IDH1-mutated or IDH2-mutated solid tumours

INTRODUCTION

High-grade chondrosarcoma, high-grade glioma and intrahepatic cholangiocarcinoma are aggressive types of cancer with a dismal outcome. This is due to the lack of effective treatment options, emphasising the need for novel therapies. Mutations in the genes IDH1 and IDH2 (isocitrate dehydrogenase 1 and 2) occur in 60% of chondrosarcoma, 80% of WHO grade II-IV glioma and 20% of intrahepatic cholangiocarcinoma. IDH1/2-mutated cancer cells produce the oncometabolite D-2-hydroxyglutarate (D-2HG) and are metabolically vulnerable to treatment with the oral antidiabetic metformin and the oral antimalarial drug chloroquine.

METHODS AND ANALYSIS

We describe a dose-finding phase Ib/II clinical trial, in which patients with IDH1/2-mutated chondrosarcoma, glioma and intrahepatic cholangiocarcinoma are treated with a combination of metformin and chloroquine. Dose escalation is performed according to a 3+3 dose-escalation scheme. The primary objective is to determine the maximum tolerated dose to establish the recommended dose for a phase II clinical trial. Secondary objectives of the study include (1) determination of pharmacokinetics and toxic effects of the study therapy, for which metformin and chloroquine serum levels will be determined over time; (2) investigation of tumour responses to metformin plus chloroquine in IDH1/2-mutated cancers using CT/MRI scans; and (3) whether tumour responses can be measured by non-invasive D-2HG measurements (mass spectrometry and magnetic resonance spectroscopy) of tumour tissue, serum, urine, and/or bile or next-generation sequencing of circulating tumour DNA (liquid biopsies). This study may open a novel treatment avenue for IDH1/2-mutated high-grade chondrosarcoma, glioma and intrahepatic cholangiocarcinoma by repurposing the combination of two inexpensive drugs that are already approved for other indications.

ETHICS AND DISSEMINATION

This study has been approved by the medical-ethical review committee of the Academic Medical Center, Amsterdam, The Netherlands. The report will be submitted to a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

This article was registered at ClinicalTrials.gov identifier (NCT02496741): Pre-results.

Rebamipide induces the gastric mucosal protective factor, cyclooxygenase-2, via activation of 5'-AMP-activated protein kinase

Rebamipide, an amino acid derivative of 2(1H)-quinolinone, has been used for mucosal protection, healing of gastroduodenal ulcers, and treatment of gastritis. Induction of cyclooxygenase (COX)-2, a gastric mucosal protective factor, by rebamipide has been suggested as the major mechanism of the drug action. However, how rebamipide induces COX-2 at the molecular level needs further investigation. In this study, the molecular mechanism underlying the induction of COX-2 by rebamipide was investigated. In gastric carcinoma cells and macrophage cells, rebamipide induced phosphorylation of AMP-activated protein kinase (AMPK), leading to phosphorylation of acetyl-CoA carboxylase (ACC), a substrate of AMPK. The induction of COX-2 by rebamipide was dependent on AMPK activation because compound C, an AMPK inhibitor, abolished COX-2 induction by rebamipide. In a mouse ulcer model, rebamipide protected against hydrochloric acid/ethanol-induced gastric ulcer, and these protective effects were deterred by co-administration of compound C. In parallel, in the gastric tissues, rebamipide increased the phosphorylation AMPK, whereas compound C reduced the levels of COX-2 and phosphorylated ACC, which were increased by rebamipide. Taken together, the activation of AMPK by rebamipide may be a molecular mechanism that contributes to induction of COX-2, probably resulting in protection against gastric ulcers.

Hippo transducer TAZ promotes epithelial mesenchymal transition and supports pancreatic cancer progression

Transcriptional co-activator with PDZ binding motif (TAZ) is a transducer of the Hippo pathway and promotes cancer development and progression. In the present study, we sought to determine the roles and underlying mechanisms of elevated expression and activation of TAZ in pancreatic cancer development and progression. The mechanistic role of TAZ and Hippo signaling in promotion of pancreatic cancer development and progression was examined using cell culture, molecular biology, and mouse models. The relevance of our experimental and mechanistic findings was validated using human pancreatic tumor specimens. We found that TAZ expression was markedly higher in pancreatic tumors than in normal pancreatic tissue. Further analysis of the correlation of TAZ expression with tissue microarray clinicopathologic parameters revealed that this expression was positively associated with tumor differentiation. Also, TAZ expression was higher in pancreatic cancer cell lines than in pancreatic ductal epithelial cells. TAZ activation in pancreatic cancer cells promoted their proliferation, migration, invasion, and epithelial-mesenchymal transition. Further mechanistic studies demonstrated that aberrant expression and activation of TAZ in pancreatic cancer cells resulted from suppression of the expression of Merlin, a positive regulator upstream of the Hippo pathway, and that the oncogenic function of TAZ in pancreatic cancer cells was mediated by TEA/ATTS domain transcription factors. Therefore, TAZ functioned as an oncogene and promoted pancreatic cancer epithelial-mesenchymal transition and progression. TAZ thus may be a target for effective therapeutic strategies for pancreatic cancer.

Metformin potentiates the anticancer activities of gemcitabine and cisplatin against cholangiocarcinoma cells in vitro and in vivo

Metformin, an oral biguanide drug used to treat type 2 diabetes, has displayed anticancer activities in several types of cancer cells. The combination of gemcitabine and cisplatin is the standard chemotherapy regimen for cholangiocarcinoma, but its benefit is limited. The present study aimed to investigate whether metformin could enhance the activities of gemcitabine and cisplatin against cholangiocarcinoma, and the underlying mechanisms. Metformin inhibited the proliferation of human cholangiocarcinoma RBE and HCCC-9810 cells and induced cell cycle arrest at the G0/G1 phase by increasing the activation of AMP-activated protein kinase (AMPK) pathways. Metformin upregulated the expression of p21Waf1 and p27kip1, and downregulated the expression of cyclin D1, a key protein required for cell cycle progression. The combination of gemcitabine and cisplatin inhibited the proliferation and induced the apoptosis of human cholangiocarcinoma cells by inducing the phosphorylation of AMPK, downregulating cyclin D1, and activating caspase-3. Administration of metformin enhanced the efficacy of gemcitabine and cisplatin to suppress the growth of cholangiocarcinoma tumors established in experimental models by inhibiting cell proliferation and inducing cell apoptosis through their effects on AMPK, cyclin D1 and caspase-3. Given that metformin has been used to treat type 2 diabetes patients for over half a century due to its superior safety profile, the results presented here indicate that metformin may be a potent agent for enhancing the efficacy of gemcitabine and cisplatin in the treatment of cholangiocarcinoma.