Metformin reduces gastric cancer risk in patients with type 2 diabetes mellitus

The causal relationship between anti-diabetic drugs and gastrointestinal disorders: a drug-targeted mendelian randomization study

BACKGROUND

The incidence of diabetic gastrointestinal diseases is increasing year by year. This study aimed to investigate the causal relationship between antidiabetic medications and gastrointestinal disorders, with the goal of reducing the incidence of diabetes-related gastrointestinal diseases and exploring the potential repurposing of antidiabetic drugs.

METHODS

We employed a two-sample Mendelian randomization (TSMR) design to investigate the causal association between antidiabetic medications and gastrointestinal disorders, including gastroesophageal reflux disease (GERD), gastric ulcer (GU), chronic gastritis, acute gastritis, Helicobacter pylori infection, gastric cancer (GC), functional dyspepsia (FD), irritable bowel syndrome (IBS), ulcerative colitis (UC), Crohn's disease (CD), diverticulosis, and colorectal cancer (CRC). To identify potential inhibitors of antidiabetic drug targets, we collected single-nucleotide polymorphisms (SNPs) associated with metformin, GLP-1 receptor agonists, SGLT2 inhibitors, DPP-4 inhibitors, insulin, and its analogs, thiazolidinediones, sulfonylureas, and alpha-glucosidase inhibitors from published genome-wide association study statistics. We then conducted a drug-target Mendelian randomization (MR) analysis using inverse variance weighting (IVW) as the primary analytical method to assess the impact of these inhibitors on gastrointestinal disorders. Additionally, diabetes was selected as a positive control.

RESULTS

Sulfonylureas were found to significantly reduce the risk of CD (IVW: OR [95% CI] = 0.986 [0.978, 0.995], p = 1.99 × 10- 3), GERD (IVW: OR [95% CI] = 0.649 [0.452, 0.932], p = 1.90 × 10- 2), and chronic gastritis (IVW: OR [95% CI] = 0.991 [0.982, 0.999], p = 4.50 × 10- 2). However, they were associated with an increased risk of GU development (IVW: OR [95%CI] = 2 0.761 [1.259, 6.057], p = 1 0.12 × 10- 2).

CONCLUSIONS

The results indicated that sulfonylureas had a positive effect on the prevention of CD, GERD, and chronic gastritis but a negative effect on the development of gastric ulcers. However, our research found no causal evidence for the impact of metformin, GLP-1 agonists, SGLT2 inhibitors, DPP 4 inhibitors, insulin and its analogs, thiazolidinediones, or alpha-glucosidase inhibitors on gastrointestinal diseases.

Bridging the gap: exploring the causal relationship between metformin and tumors

Objective

Numerous studies have reported that metformin can reduce the risk of tumor development. However, some of the results of these studies are conflicting, necessitating a more reliable evaluation.

Methods

We conducted a Mendelian randomization phenome-wide association study (MR-PheWAS) of tumors to explore the causal relationship between metformin and tumors. Two cohorts of patients taking metformin were obtained from the UK Biobank. Complete phenotype data of the tumors were obtained from FinnGen_R10. We elucidated the causal relationship using a two-sample Mendelian randomization (MR) analysis. More importantly, we conducted a meta-analysis to ensure relatively unbiased results. In the MR analysis, we used the inverse-variance weighted (IVW) method as the main outcome indicator. Subsequently, two cohorts were integrated for the meta-analysis. Finally, we investigated the mechanisms through mediational MR analysis.

Results

MR analysis revealed that metformin might have a causal relationship with 13 tumor-associated phenotypes in the training cohort. Four phenotypes were validated in the testing cohort. In the training and testing cohorts, metformin exhibited a protective effect against brain meningiomas and malignant neoplasms of the breast (HER-positive), oral cavity, tonsils, and the base of the tongue. Intriguingly, after integrating the results of the two cohorts for the meta-analysis, 12 results were statistically significant. Mediational MR analysis suggested that the effects of metformin on brain meningiomas may be weakened by the presence of the family Oxalobacteraceae.

Conclusion

Metformin exhibits potential preventive and therapeutic effects on four types of tumors: brain meningioma, malignant neoplasms of the breast (HER-positive), oral cavity and tonsils, and the base of the tongue. Large randomized controlled trials are required to confirm these findings.

Human Aging and Age-Related Diseases: From Underlying Mechanisms to Pro-Longevity Interventions

As human life expectancy continues to rise, becoming a pressing global concern, it brings into focus the underlying mechanisms of aging. The increasing lifespan has led to a growing elderly population grappling with age-related diseases (ARDs), which strains healthcare systems and economies worldwide. While human senescence was once regarded as an immutable and inexorable phenomenon, impervious to interventions, the emerging field of geroscience now offers innovative approaches to aging, holding the promise of extending the period of healthspan in humans. Understanding the intricate links between aging and pathologies is essential in addressing the challenges presented by aging populations. A substantial body of evidence indicates shared mechanisms and pathways contributing to the development and progression of various ARDs. Consequently, novel interventions targeting the intrinsic mechanisms of aging have the potential to delay the onset of diverse pathological conditions, thereby extending healthspan. In this narrative review, we discuss the most promising methods and interventions aimed at modulating aging, which harbor the potential to mitigate ARDs in the future. We also outline the complexity of senescence and review recent empirical evidence to identify rational strategies for promoting healthy aging.

Metformin suppresses gastric cancer progression by disrupting the STAT1-PRMT1 axis

Gastric cancer (GC) is a common form of cancer and the leading cause of cancer-related deaths worldwide. Chemotherapy is the primary treatment for patients with unresectable or partially resectable GC. However, its adverse effects and chemoresistance greatly restrict its applicability and efficacy. Although HER2-targeted therapy and immunotherapy have been successfully used for GC treatment, their beneficial population is limited. To expand the range of cancer treatments, drug repurposing has emerged as a promising strategy. In this study, we evaluated the potential of Metformin, an oral anti-hyperglycemic agent, to suppress GC progression both in vivo and in vitro. Functional investigations showed that Metformin significantly inhibits GC proliferation and migration. Furthermore, we discovered that Metformin bound and disrupted STAT1 phosphorylation, inhibiting PRMT1 expression and consequently GC progression. In conclusion, our study not only provides further evidence for the anti-GC role of Metformin but also identifies the direct target mediating the tumor-inhibitory effects of Metformin in GC.

Effects of metformin on cancers in experimental and clinical studies: Focusing on autophagy and AMPK/mTOR signaling pathways

Metformin (MET) is a preferred drug for the treatment of type 2 diabetes mellitus. Recent studies show that apart from its blood glucose-lowering effects, it also inhibits the development of various tumours, by inducing autophagy. Various studies have confirmed the inhibitory effects of MET on cancer cell lines' propagation, migration, and invasion. The objective of the study was to comprehensively review the potential of MET as an anticancer agent, particularly focusing on its ability to induce autophagy and inhibit the development and progression of various tumors. The study aimed to explore the inhibitory effects of MET on cancer cell proliferation, migration, and invasion, and its impact on key signaling pathways such as adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and PI3K. This review noted that MET exerts its anticancer effects by regulating key signalling pathways such as phosphoinositide 3-kinase (PI3K), LC3-I and LC3-II, Beclin-1, p53, and the autophagy-related gene (ATG), inhibiting the mTOR protein, downregulating the expression of p62/SQSTM1, and blockage of the cell cycle at the G0/G1. Moreover, MET can stimulate autophagy through pathways associated with the 5' AMPK, thereby inhibiting he development and progression of various human cancers, including hepatocellular carcinoma, prostate cancer, pancreatic cancer, osteosarcoma, myeloma, and non-small cell lung cancer. In summary, this detailed review provides a framework for further investigations that may appraise the autophagy-induced anticancer potential of MET and its repurposing for cancer treatment.

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.

The Relationship between Metformin Consumption and Cancer Risk: An Updated Umbrella Review of Systematic Reviews and Meta-Analyses

Background

Considering that metformin is widely used in the treatment of diabetes, and its protective role against various malignancies, the strength and validity of the available evidence from related systematic reviews and meta-analysis were evaluated.

Methods

Scopus, PubMed, Embase, Cochrane, Web of science databases, and Google Scholar and manual screening of retrieved references were systematically searched from their inception dates to 24 March 2020 by extracting the effect size (Odds ratios (OR) and relative risk (RR) in each study. To present the forest plot of effect of metformin on each cancer, Stata version 14.2 was used.

Results

This study included 36 meta-analysis studies and 620 original research studies (26 randomized control trials studies and 594 observational studies (cohort, case-control)) covering 15 different cancers. Overall, metformin medication prevented different cancers, including ovarian cancer (OR = 0.76, 95% CI: 0.62,0.93), cervical cancer (OR = 0.60, 95% CI: 0.43, 0.83), endometrial cancer (OR = 1.05, 95% CI: 0.82,1.35), liver cancer (OR = 0.59, 95% CI: 0.47,0.74), pancreatic cancer (OR = 0.59, 95%CI 0.50,0.69), head and neck cancer (OR = 0.71, 95% CI: 0.61,0.83), stomach cancer (OR = 0.72, 95% CI: 0.26,1.99), colorectal cancer (OR = 0.73, 95% CI: 0.59,0.91), colorectal adenoma cancer (OR = 0.75, 95% CI: 0.65,0.86), colon cancer (OR = 0.79, 95% CI: 0.69,0.91), esophagus cancer (OR = 0.90, 95% CI: 0.83,0.98), lung cancer (OR = 0.92, CI95%:0.85,0.99), breast cancer (OR = 0.93, 95% CI: 0.84,1.02), prostate cancer (OR = 0.94, 95% CI: 0.85-1.04), and bladder cancer (OR = 0.94 95% CI: 0.64,1.38).

Conclusions

Treatment with metformin can significantly decrease the chance of all cancers with larger preventive effect on hepatocellular carcinoma and smaller preventive effect on lung and breast cancers.

Metformin induces autophagy of cisplatin-resistant human gastric cancer cells in addition to apoptosis

Metformin has been used to treat cases of type 2 diabetes mellitus, and mounting studies have shown that metformin can act alone or in synergy with other anticancer agents to achieve anti-cancer efficacies on various types of tumors. However, the role of metformin in either inducing autophagy and cisplatin-resistance of human gastric cancer (GC) cells has never been examined. The study has established a cisplatin-resistant GC cell line and investigated the effects of metformin on inducing autophagy on it. The results demonstrated that treatment with metformin can concentration-dependently suppress the cell viability and cell confluence of cisplatin-resistant GC cells, while having no effects on human primary stomach epithelial cells (HPSEC). For the first time, we found that metformin can significantly increase the acidic vesicular organelles (AVO) level and decrease the acridine orange (AO) level spontaneously in the cisplatin-resistant GC cells. Thus, we further checked the other markers, Atg5, Atg12 and LC3-II, which showed that metformin indeed induced autophagy in the cisplatin-resistant GC cells. In addition, treatment of 3-Methyladenine (3-MA) can significantly rescue the metformin-induced autophagy. At the same time, metformin can induce the alterations of apoptosis-associated signal molecules, such as caspase-3 and caspase-7 activities. Overall, the pilot study provided evidence for metformin induced autophagy in addition to apoptosis, making it as an effective anticancer drug for the therapy of cisplatin-resistant GC. Killing the cisplatin-resistant GC cells with non-toxic metformin via both autophagy and apoptosis might extend its usefulness in our fighting with chemo-resistance of gastric cancer cells.

Chronic metformin intake and gastric cancer: A pooled analysis within the Stomach cancer Pooling (StoP) Project

INTRODUCTION

The association between chronic use of metformin and risk of gastric cancer (GC) has been investigated with contradicting results. We aimed to study the association between chronic use of metformin and GC by using data from the Stomach cancer Pooling (StoP) Project, an epidemiological consortium of case-control studies on GC.

METHODS

Data from three studies of the StoP Project with available information on metformin intake were analyzed. Multivariable logistic regression models were used to estimate study-specific odds ratios (ORs) and 95% confidence intervals (CIs) for the association between chronic use of metformin and GC risk. Analyses were adjusted for sex, age, socioeconomic status, body mass index, smoking status, alcohol drinking status, and history of diabetes. Study-specific ORs and 95% CIs were then pooled with a random-effects model. The dose-response relationship between the duration of metformin intake and GC was assessed with a one-stage logistic model, and the duration of intake was modelled using second-order fractional polynomials.

RESULTS

The OR of GC in metformin users versus non-users was 1.01 (95% CI=0.61, 1.67). The association between metformin and GC did not change among different strata of study participants' characteristics or when restricting the analyses to those with a history of diabetes. The dose-response analysis showed a slightly reducing trend in the OR of GC and a borderline significant association with increasing duration of metformin intake.

CONCLUSIONS

The results of our study do not clearly support an association between chronic use of metformin and GC, warranting further research.

Mechanism Underlying Metformin Action and Its Potential to Reduce Gastric Cancer Risk

Diabetes mellitus is associated with a high risk of developing gastric cancer (GC). Metformin, which is conventionally used to treat type 2 diabetes, induces AMP-activated protein kinase signaling and suppresses gluconeogenesis. Recent studies have reported that metformin is associated with beneficial effects in cancer prevention and treatment owing to its anti-tumor effects. This makes metformin a potential medication for GC therapy. However, contradicting reports have emerged regarding the efficacy of metformin in reducing the risk of GC. This review summarizes the impact of metformin on mitigating GC risk by analyzing clinical databases. The mechanism underlying the anti-tumor effect of metformin on GC is also discussed.

Immunomodulatory and Antiaging Mechanisms of Resveratrol, Rapamycin, and Metformin: Focus on mTOR and AMPK Signaling Networks

Aging results from the progressive dysregulation of several molecular pathways and mTOR and AMPK signaling have been suggested to play a role in the complex changes in key biological networks involved in cellular senescence. Moreover, multiple factors, including poor nutritional balance, drive immunosenescence progression, one of the meaningful aspects of aging. Unsurprisingly, nutraceutical and pharmacological interventions could help maintain an optimal biological response by providing essential bioactive micronutrients required for the development, maintenance, and the expression of the immune response at all stages of life. In this regard, many studies have provided evidence of potential antiaging properties of resveratrol, as well as rapamycin and metformin. Indeed, in vitro and in vivo models have demonstrated for these molecules a number of positive effects associated with healthy aging. The current review focuses on the mechanisms of action of these three important compounds and their suggested use for the clinical treatment of immunosenescence and aging.

[Metformin and malignant neoplasms: a possible mechanism of antitumor action and prospects for use in practice]

Metformin is a first-line antidiabetic drug for the treatment of type 2 diabetes mellitus (DM2); its molecular target is AMP-activated protein kinase (AMPK), which is involved in many metabolic processes. Metformin not only reduces blood glucose levels and improves insulin sensitivity, but also inhibits lipolysis and reduces cardiovascular risk in patients with DM2. In recent years, it has been proven that metformin slows down the aging process, stimulates hair growth, eliminates cognitive impairment, and also has an antitumor effect. Most basic studies have shown that metformin inhibits the growth of tumor cells and promotes cellular apoptosis, while clinical studies show contradictory results. This discrepancy can be explained by the difference in the concentration of metformin between basic and clinical studies. The maximum daily dose of metformin for patients with DM2 is 2500 mg / day, and the dose used in basic research was much higher. Metformin directly activates the AMPK signaling pathway, inhibits the production of reactive oxygen species, induces the activation of mTORC1, inhibits cyclin D1, which leads to a reduction in the risk of the occurrence and development of malignant neoplasms. In addition, metformin indirectly inhibits tumor growth, proliferation, invasion and metastasis by reducing the concentration of glucose in the blood, insulin resistance, as well as by reducing inflammation and affecting the tumor microenvironment. Glycolysis plays an important role in the energy metabolism of tumors, and metformin is able to have an inhibitory effect on it. Currently, studies of the mechanism of antitumor effects of metformin are becoming more extensive and in-depth, but there are still some contradictions.

Aspirin, metformin, and statin use on the risk of gastric cancer: A nationwide population-based cohort study in Korea with systematic review and meta-analysis

BACKGROUND/AIMS

Although several chemopreventive drugs against gastric cancer have been proposed, their effects have not been fully evaluated. We examined the impacts of aspirin, metformin, and statin use on gastric cancer development in a population-based cohort in Korea.

METHODS

We analyzed the association between potential chemopreventive drugs-aspirin, metformin, and statin-and gastric cancer through the Observational Medical Outcomes Partnership Common Data Model-based Korean nationwide cohort. Use of aspirin, metformin, and statin was defined by ≥365 days of prescriptions for each drug in the general population. To summarize the current evidence, we further performed a systematic review and meta-analysis of the impact of aspirin, metformin, and statin on gastric cancer development.

RESULTS

After propensity score matching, 31,839, 6764, and 10,251 subjects were observed for medians of 4.7, 4.2, and 4.2 years for aspirin, metformin, and statin analysis, respectively. Use of aspirin or statin was associated with lower risks of gastric cancer compared to their non-use, respectively (hazard ratio [HR] [95% confidence interval [CI]]: aspirin, 0.72 [0.60-0.85], p < 0.01; statin, 0.67 [0.49-0.92], p = 0.01). However, no association was observed between metformin use and gastric cancer development (HR [95% CI]: 0.85 [0.59-1.23], p = 0.40). A subgroup of subjects with diabetes mellitus showed a lower risk of gastric cancer development with statin use. The meta-analysis showed the highest effect size of gastric cancer development for statin, followed by aspirin and metformin.

CONCLUSIONS

Statin and aspirin use were associated with significantly reduced risks of gastric cancer development, while the use of metformin was not associated with the gastric cancer risk. The protective effect of statin against gastric cancer was also significant in patients with diabetes mellitus.

Adverse Effects of Metformin From Diabetes to COVID-19, Cancer, Neurodegenerative Diseases, and Aging: Is VDAC1 a Common Target?

Metformin has been used for treating diabetes mellitus since the late 1950s. In addition to its antihyperglycemic activity, it was shown to be a potential drug candidate for treating a range of other diseases that include various cancers, cardiovascular diseases, diabetic kidney disease, neurodegenerative diseases, renal diseases, obesity, inflammation, COVID-19 in diabetic patients, and aging. In this review, we focus on the important aspects of mitochondrial dysfunction in energy metabolism and cell death with their gatekeeper VDAC1 (voltage-dependent anion channel 1) as a possible metformin target, and summarize metformin’s effects in several diseases and gut microbiota. We question how the same drug can act on diseases with opposite characteristics, such as increasing apoptotic cell death in cancer, while inhibiting it in neurodegenerative diseases. Interestingly, metformin’s adverse effects in many diseases all show VDAC1 involvement, suggesting that it is a common factor in metformin-affecting diseases. The findings that metformin has an opposite effect on various diseases are consistent with the fact that VDAC1 controls cell life and death, supporting the idea that it is a target for metformin.

Metformin and Risk of Malignant Brain Tumors in Patients with Type 2 Diabetes Mellitus

The risk of malignant brain tumors associated with metformin use has rarely been investigated in humans. This retrospective cohort study investigated such an association. Patients with new-onset type 2 diabetes mellitus diagnosed from 1999 to 2005 in the nationwide database of Taiwan’s national health insurance were used to enroll study subjects. We first identified an unmatched cohort of 153,429 ever users and 16,222 never users of metformin. A cohort of 16,222 ever users and 16,222 never users matched on propensity score was then created from this unmatched cohort. All patients were followed up from 1 January 2006 until 31 December 2011. The incidence density was calculated and hazard ratios were derived from Cox regression incorporated with the inverse probability of treatment weighting using a propensity score. The results showed that 27 never users and 155 ever users developed malignant brain tumors in the unmatched cohort. The incidence rate was 37.11 per 100,000 person-years in never users and 21.39 per 100,000 person-years in ever users. The overall hazard ratio comparing ever users versus never users was 0.574 (95% confidence interval: 0.381–0.863). The respective hazard ratios comparing the first (<27.13 months), second (27.13–58.33 months), and third (>58.33 months) tertiles of cumulative duration of metformin therapy versus never users were 0.897 (0.567–1.421), 0.623 (0.395–0.984), and 0.316 (0.192–0.518). In the matched cohort, the overall hazard ratio was 0.317 (0.149–0.673) and the respective hazard ratios were 0.427 (0.129–1.412), 0.509 (0.196–1.322), and 0.087 (0.012–0.639) for the first, second, and third tertile of cumulative duration of metformin therapy. In conclusion, this study shows a risk reduction of malignant brain tumors associated with metformin use in a dose–response pattern. The risk reduction is more remarkable when metformin has been used for approximately 2–5 years.

Metformin and Gastrointestinal Cancer Development in Newly Diagnosed Type 2 Diabetes: A Population-Based Study in Korea

INTRODUCTION

Clinical studies have produced conflicting results on the effects of metformin on gastrointestinal cancer development. We aimed to investigate the association between metformin use and stomach, colon, liver, and pancreatic cancer development among patients with newly diagnosed, drug-naïve type 2 diabetes.

METHODS

This retrospective study evaluated propensity score-matched patients with newly diagnosed type 2 diabetes from the Korean National Health Insurance Service database. Metformin users were categorized into tertiles according to the cumulative dose or duration of metformin treatment, and the risks of gastrointestinal cancers were compared.

RESULTS

Metformin users had reduced risks of developing stomach cancer (hazard ratio [HR]: 0.841, 95% confidence interval [CI]: 0.797-0.887), colon cancer (HR: 0.865, 95% CI: 0.822-0.91), and liver cancer (HR: 0.709, 95% CI: 0.675-0.746; P < 0.001). However, metformin users did not have a reduced overall risk of pancreatic cancer (HR: 1.335, 95% CI: 1.209-1.475; P < 0.001). The risks tended to decrease at higher cumulative doses and durations of metformin use, with significantly reduced risks of all 4 cancers at the highest cumulative dose (≥1,200,000 mg) and the longest duration (≥2,000 days) of metformin use.

DISCUSSION

This population-based data suggest that metformin could be associated with reductions in the risks of stomach, colon, and liver cancers, as well a reduced risk of pancreatic cancer in some subgroups. Metformin has benefit as a first-line treatment for type 2 diabetes mellitus. A further role in cancer risk reduction could be studied in controlled trials.

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.

Chemopreventive Effect of Metformin on Gastric Cancer Development

Although Helicobacterpylori infection is the most important causative factor for gastric cancer (GC), H. pylori eradication alone does not completely eliminate the GC risk. In addition to H. pylori eradication, other risk factors for GC should be identified and targeted. Diabetes mellitus (DM) confers a 20% increased risk of GC, which could be mediated via several biological mechanisms including the stimulation of cell proliferation via hyperinsulinemia and increased insulin-growth factor production, the promotion of angiogenesis, and DNA damage. With a current global prevalence of 9.3% and a predicted rise to 10.2% by 2030, DM could contribute substantially to the burden of GC cases worldwide. Emerging evidence showed that metformin possesses chemopreventive effects via both direct (e.g., adenosine monophosphate-activated protein kinase activation and subsequent inhibition of the mammalian target of rapamycin pathway) and indirect (e.g., modulation of the interaction between tumor cells and their microenvironment and gut microbiota) pathways. A recent meta-analysis of observational studies showed that metformin use was associated with 24% lower GC risk. However, many available observational studies related to metformin effects suffered from biases including the failure to adjust for the H. pylori infection status and serial glycemic control and time-related biases. Future prospective studies addressing these pitfalls are needed.

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 and risk of cancer among patients with type 2 diabetes mellitus: A systematic review and meta-analysis

AIM

We carried out this meta-analysis on all published studies to estimate the overall cancer risk of the use of metformin in T2DM patients.

METHODS

We searched the PubMed, Embase and CNKI databases for all articles within a range of published years from 2007 to 2019 on the association between the use of metformin and cancer risk in T2DM patients. The odds ratio (OR) corresponding to the 95% confidence interval (95% CI) was used to assess the association using a random-effect meta-analysis.

RESULTS

Finally, 67 studies met the inclusion criteria for this study, with 10,695,875 T2DM patients and 145,108 cancer cases. Overall, For T2DM patients of ever vs. never metformin users, there was statistical evidence of significantly decreased cancer risk was found to be associated with ever metformin users (OR=0.70, 95% CI=0.65-0.76). Considering T2DM may be a specific and independent risk factor for various forms of cancer, due to its particular metabolic characteristics of glucose intolerance and hyperinsulinemia, we performed a comparison to estimate the effects of metformin on cancer risk with other anti-diabetes medications (ADMs), our results found significantly decreased cancer risk to be associated with the use of metformin (OR=0.80, 95% CI=0.73-0.87).

CONCLUSION

Our meta-analysis indicated that metformin may be a independent protective factor for cancer risk in T2DM patients.

Aging and age-related diseases: from mechanisms to therapeutic strategies

Aging is a physiological process mediated by numerous biological and genetic pathways, which are directly linked to lifespan and are a driving force for all age-related diseases. Human life expectancy has greatly increased in the past few decades, but this has not been accompanied by a similar increase in their healthspan. At present, research on aging biology has focused on elucidating the biochemical and genetic pathways that contribute to aging over time. Several aging mechanisms have been identified, primarily including genomic instability, telomere shortening, and cellular senescence. Aging is a driving factor of various age-related diseases, including neurodegenerative diseases, cardiovascular diseases, cancer, immune system disorders, and musculoskeletal disorders. Efforts to find drugs that improve the healthspan by targeting the pathogenesis of aging have now become a hot topic in this field. In the present review, the status of aging research and the development of potential drugs for aging-related diseases, such as metformin, rapamycin, resveratrol, senolytics, as well as caloric restriction, are summarized. The feasibility, side effects, and future potential of these treatments are also discussed, which will provide a basis to develop novel anti-aging therapeutics for improving the healthspan and preventing aging-related diseases.

Immortal time bias exaggerates the effect of metformin on the risk of gastric cancer: A meta-analysis

High heterogeneity has been reported among epidemiological studies exploring the relationship between metformin and the risk of gastric cancer. Immortal time bias might be one of the vital factors causing heterogeneity because of its widespread existence in pharmacological observational studies and it could severely exaggerate the drug's effectiveness. Immortal time bias could occur in an observational study if exposure status is determined based on a measurement or event that occurs after baseline. In this study, we aimed to assess whether immortal time bias is responsible for the false assumption that metformin reduces the risk of gastric cancer. We searched PubMed, Embase, Web of Science and Cochrane Library databases for relevant studies from the inception to August 9, 2020. The strength of the relationship was assessed using pooled relative risks (RRs) with corresponding 95% confidence intervals (95% CIs). Statistical analyses were carried out using a random-effects model. Pooled RR from 6 cohort studies with immortal time bias found a clear 33% reduced risk associated with metformin use (RR = 0.67, 95% CI = 0.59, 0.77; P < 0.001; I² = 48.5%). However, pooled RR from 8 cohort studies without immortal time bias indicated no association between the use of metformin and gastric cancer risk (RR = 0.95, 95% CI = 0.85, 1.05; P = 0.317; I² = 64.5%). From a univariate meta-regression model, the presence of immortal time bias was associated with a significant reduction of 29% in the effect estimate of metformin on gastric cancer risk (ratio of RR = 0.71, 95% CI = 0.58, 0.86; P = 0.002). This meta-analysis indicates that metformin use has no protective effect on gastric cancer risk. The relationship between metformin use and gastric cancer risk has been exaggerated as a result of the presence of immortal time bias. Further studies are required to confirm the results by controlling for immortal time bias based on appropriate study designs and statistical methods.

Metformin and Malignant Tumors: Not Over the Hill

Malignant tumors are a major cause of death, and their incidence is increasing worldwide. Although the survival rate for some cancers has improved, treatments for other malignant tumors are limited, and their mortality rate continues to increase. People with type 2 diabetes have a higher risk of malignant tumors and a higher mortality rate than those without diabetes. Metformin is a commonly used hypoglycemic drug. In recent years, a growing number of studies have indicated that metformin has antitumor effects and increases the sensitivity of malignant tumors to chemotherapy. However, the effect of metformin on different tumors is currently controversial, and the mechanism of metformin's antitumor action is not fully understood. Insights into the effect of metformin on malignant tumors and the possible mechanism may contribute to the development of antitumor drugs.

Resveratrol, Rapamycin and Metformin as Modulators of Antiviral Pathways

Balanced nutrition and appropriate dietary interventions are fundamental in the prevention and management of viral infections. Additionally, accurate modulation of the inflammatory response is necessary to achieve an adequate antiviral immune response. Many studies, both in vitro with mammalian cells and in vivo with small animal models, have highlighted the antiviral properties of resveratrol, rapamycin and metformin. The current review outlines the mechanisms of action of these three important compounds on the cellular pathways involved with viral replication and the mechanisms of virus-related diseases, as well as the current status of their clinical use.

Metformin use reduced the risk of stomach cancer in diabetic patients in Korea: an analysis of Korean NHIS-HEALS database

BACKGROUND

Diabetes mellitus (DM) increases atherosclerotic cardiovascular complications and cancer risks. Stomach cancer is the most common cancer in Korea. Although the survival rate of stomach cancer has improved, the disease burden is still high.

METHODS

This retrospective study investigated the association between metformin use and stomach cancer incidence in a Korean population using the National Health Insurance Service-National Health Screening Cohort database. Participants aged 40-80 years old at the baseline period (2002-2003) were enrolled. The study population was categorized into three groups of metformin non-users with DM, metformin users with DM, and individuals without DM (No DM group).

RESULTS

A total of 347,895 participants (14,922 metformin non-users, 9891 metformin users, and 323,082 individuals without DM) were included in the final analysis. The median follow-up duration was 12.70 years. The estimated cumulative incidence of stomach cancer was highest in metformin non-users and lowest in the No DM group (men vs. women: 3.75 vs. 1.97% in metformin non-users, 2.91 vs. 1.53% in metformin users, and 2.54 vs. 0.95% in the No DM group). Compared with metformin non-users, the hazard ratios (95% confidence intervals) for stomach cancer incidence of metformin users and the No DM group were 0.710 (0.579-0.870) and 0.879 (0.767-1.006) in men and 0.700 (0.499-0.981) and 0.701 (0.544-0.903) in women, respectively, after full adjustment.

CONCLUSIONS

Metformin users with DM in the Korean population were at lower risk of stomach cancer incidence after controlling for potential confounding factors.

Metformin and Biliary Tract Cancer in Patients With Type 2 Diabetes

Aim

This retrospective cohort study evaluated whether metformin use in patients with type 2 diabetes mellitus might reduce the risk of biliary tract cancer (BTC); and explored whether metformin use might affect the overall survival in patients who developed BTC.

Methods

New-onset type 2 diabetes patients aged 25–75 years during 1999–2005 were enrolled from the Taiwan’s National Health Insurance and followed up until December 31, 2011. A total of 287,995 ever users and 16,229 never users were identified (unmatched original cohort) and a 1:1 matched pairs of 16,229 ever users and 16,229 never users based on propensity score (PS) were created (matched cohort). Hazard ratios were estimated by three Cox regression models: 1) adjusted for PS; 2) incorporated with the inverse probability of treatment weighting using PS; and 3) all covariates treated as independent variables. Overall survival was compared between ever users and never users of metformin who developed BTC.

Results

In the unmatched cohort, 73 never users and 523 ever users developed BTC, with respective incidence of 100.36 and 38.06 per 100,000 person-years. An overall risk reduction was observed in metformin users in all three regression models with respective hazard ratio (95% confidence interval) of 0.442 (0.344-0.568), 0.377 (0.295-0.481), and 0.477 (0.370-0.615). The tertile analyses showed a dose-response pattern with a neutral effect in the first tertile when metformin use was <2 years and a significant risk reduction in the second and third tertiles. Findings in the matched cohort were consistent with those observed in the unmatched cohort. The overall survival did not differ significantly between ever and never users of metformin among patients who developed BTC.

Conclusions

Metformin significantly reduces the overall risk of BTC by 50%–60%. A dose-response effect is observed and users of approximately 2 years show significantly reduced risk. However, metformin does not affect the overall survival in patients with BTC.

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.

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 Use and Gastric Cancer Risk in Diabetic Patients After Helicobacter pylori Eradication

BACKGROUND

Although prior studies showed metformin could reduce gastric cancer (GC) risk in patients with diabetes mellitus, they failed to adjust for Helicobacter pylori infection and glycemic control. We aimed to investigate whether metformin reduced GC risk in H. pylori-eradicated diabetic patients and its association with glycemic control.

METHODS

This was a territory-wide cohort study using hospital registry database, recruiting all diabetic patients who were prescribed clarithromycin-based triple therapy for H. pylori infection from 2003 to 2012. Subjects were observed from H. pylori therapy prescription until GC diagnosis, death, or end of study (December 2015). Exclusion criteria included GC diagnosed within first year of H. pylori therapy, prior history of GC or gastrectomy, and failure of H. pylori eradication. The hazard ratio (HR) of GC with metformin (defined as at least 180-day use) was estimated by Cox model with propensity score adjustment for covariates (age, sex, comorbidities, medications [including insulin], and time-weighted average hemoglobin A1c [HbA1c]). All statistical tests were two-sided.

RESULTS

During a median follow-up of 7.1 years (IQR = 4.7-9.8), 37 (0.51%) of 7266 diabetic patients developed GC at a median age of 76.4 years (IQR = 64.8-81.5 years). Metformin use was associated with a reduced GC risk (adjusted HR = 0.49, 95% CI = 0.24 to 0.98). There was a trend towards a lower GC risk with increasing duration (Ptrend = .01) and dose of metformin (Ptrend = .02). HbA1c level was not an independent risk factor for GC.

CONCLUSIONS

Metformin use was associated with a lower GC risk among H. pylori-eradicated diabetic patients in a duration- and dose-response manner, which was independent of HbA1c level.

Metformin Promotes Beclin1-Dependent Autophagy to Inhibit the Progression of Gastric Cancer

Background

Metformin is the first-line blood sugar control drug for type 2 diabetes, but recent epidemiological studies have shown that it inhibits the growth of a variety of tumours. However, few studies have examined metformin effects on gastric cancer (GC), and the anticancer mechanism has not been fully elucidated.

Materials and Methods

We examined the inhibitory effect of metformin on GC cells by cell proliferation, migration and invasion assay. Transmission electron microscopy, confocal microscopy and Western blotting confirmed that metformin enhanced beclin1-dependent autophagy in gastric cancer cells. TCGA database and tissue chip analysis confirmed the differential expression of beclin1 in GC and adjacent tissues. Relevant functional tests verified the role of beclin1 as a tumour suppressor gene in GC. Western blotting, cell proliferation, cell migration and invasion were used to verify that metformin enhances autophagy in GC cells through the AMPK-mTOR signalling pathway. Xenograft tumour models were constructed to explore the inhibitory effect of metformin and the role of beclin1 as a suppressor on GC in vivo.

Results

In this study, we observed that metformin inhibits proliferation, migration and invasion of GC cells. Metformin could also promote beclin1-dependent autophagy in GC cells. We further discovered that beclin1 expression was downregulated in GC and that its low expression was associated with poor prognosis. Beclin1 acts as a tumour suppressor that inhibits the malignant phenotypes of GC cells in vitro and in vivo. Furthermore, we verified that metformin can upregulate beclin1-mediated autophagy to inhibit GC cells through the AMPK-mTOR signalling pathway.

Conclusion

In summary, the results revealed the role of autophagy in metformin inhibition of gastric cancer and suggest that beclin1 may be a potential target for gastric cancer therapy.

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.

A Cohort Study of Antihyperglycemic Medication Exposure and Gastric Cancer Risk

We assessed gastric cancer risk in type 2 diabetes mellitus patients. Gastric cancer patients with diabetes between 2001–2012 were identified. Four groups were analysed: combination therapy with metformin users; insulin and other medication users; metformin and insulin users; and sulfonylurea users. Standardised incidence ratios (SIRs) for gastric cancers as a ratio of the observed number of cancer cases in people with diabetes to the expected number of cancer cases in the underlying general population were calculated. A total of 99,992 patients with diabetes were analysed and 337 gastric cancer cases in patients with diabetes were observed when compared to the expected number of 400.54 gastric cancer cases, according to the cancer rates of the general population (SIR 0.84, 95% confidence interval (CI): 0.76–0.94). Lower risk of gastric cancer was found both in male and female patients with diabetes, however, risk among females was insignificantly lower. Higher gastric cancer risk was found in the group of diabetic patients treated with sulfonylureas (SIR 1.31, 95% CI: 1.04–1.65) and significantly lower risk than expected from the general population was found in the group of metformin users (SIR 0.75, 95% CI: 0.66–0.86). Type 2 diabetes mellitus was not associated with increased risk of gastric cancer. Metformin might decrease the risk of gastric cancer in patients with diabetes, while sulfonylureas may increase gastric cancer risk.

Drug Repurposing in the Development of Anticancer Agents

BACKGROUND

Research into repositioning known drugs to treat cancer other than the originally intended disease continues to grow and develop, encouraged in part, by several recent success stories. Many of the studies in this article are geared towards repurposing generic drugs because additional clinical trials are relatively easy to perform and the drug safety profiles have previously been established.

OBJECTIVE

This review provides an overview of anticancer drug development strategies which is one of the important areas of drug restructuring.

METHODS

Repurposed drugs for cancer treatments are classified by their pharmacological effects. The successes and failures of important repurposed drugs as anticancer agents are evaluated in this review.

RESULTS AND CONCLUSION

Drugs could have many off-target effects, and can be intelligently repurposed if the off-target effects can be employed for therapeutic purposes. In cancer, due to the heterogeneity of the disease, often targets are quite diverse, hence a number of already known drugs that interfere with these targets could be deployed or repurposed with appropriate research and development.

Association between Metformin and a Lower Risk of Age-Related Macular Degeneration in Patients with Type 2 Diabetes

Purpose

This population-based, retrospective cohort study was to investigate whether metformin is associated with a lower risk of subsequent age-related macular degeneration (AMD) in patients with type 2 diabetes.

Methods

Using the Taiwan National Health Insurance Research Database from 2001 to 2013, 68205 subjects with type 2 diabetes were enrolled in the study cohort. Among them, 45524 were metformin users and 22681 were nonusers. The metformin and nonmetformin groups were followed until the end of 2013. Cox regression analyses were used to estimate hazard ratios (HRs) for AMD development associated with metformin use. Confounders included for adjustment were age, sex, and comorbidities (hypertension, hyperlipidemia, coronary artery disease, obesity, diabetic retinopathy, chronic kidney disease, and insulin treatment). Furthermore, propensity score (PS) matching method was used to choose the matched sample, and PS-adjusted Cox regression was performed. Finally, how HRs changed according to metformin treatment duration and dose was also evaluated in the metformin group.

Results

After adjusting for confounders, the metformin group had a significantly lower risk of AMD (adjusted HR = 0.54; 95% confidence interval [CI], 0.50–0.58). In the PS-matched sample, the significance remained (adjusted HR = 0.57; 95% CI, 0.52–0.63). In the metformin group, the adjusted HRs for the second (1.5–4 years) and third (≥4 years) tertiles of metformin treatment duration were 0.52 and 0.14, respectively, compared with the first tertile (<1.5 years). We also found significant trends of lower HRs (all p-value for trend <0.05) with increasing total and average doses.

Conclusions

Among patients with type 2 diabetes, those who use metformin are at a significantly lower risk of developing AMD relative to individuals who do not use metformin. Also, the trend of a significantly lower AMD risk was found with a higher dose of metformin.

A cohort study of antihyperglycemic medication exposure and survival in patients with gastric cancer

Objective: We aimed to estimate survival in gastric cancer patients with type 2 diabetes mellitus (T2DM) using different antihyperglycemic medication.

Methods: Patients with gastric cancer and diabetes between 2003-2013 were identified form The Lithuanian Cancer Registry and The National Health Insurance Fund database. Cohort members were classified into five groups: four groups of T2DM patients according to treatment: metformin users; metformin and other medication users; sulphonylurea users; insulin and other medication users; and non-diabetic group. Kaplan-Meier survival analysis and Cox proportional hazards models were used to estimate gastric cancer-specific survival and overall survival.

Results: 8423 patients met eligibility criteria. Survival analysis showed no differences in gastric cancer-specific survival between non-diabetic and diabetic patient groups. Better survival was observed in the groups of patients using antihyperglycemic medication combinations with metformin, metformin alone or insulin. Lowest survival was observed in diabetic patients who were sulphonylurea users. Survival analysis comparing overall survival between non-diabetic and diabetic patients (p = 0.89) showed no evidence of survival difference between groups and survival differences between antihyperglycemic medication user groups were of borderline significance (p = 0.052).

Conclusions: Antihyperglycemic medication use was not associated with a significant effect on survival in patients with gastric cancer and T2DM.

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.

The expression of the insulin receptor in gastric cancer correlates with the HER2 status and may have putative therapeutic implications

BACKGROUND

Metabolic reprogramming in gastric cancer (GC) involves not only an alteration of glucose metabolism, but also of insulin receptor (IR) expression. We investigated if (1) GCs express the IR in cancer cells (CC-IR) and vasculature (VIR), (2) IR expression is clinically relevant and may be a novel target of GC treatment.

METHODS

467 primary GCs were studied by immunohistochemistry using an IR-specific antibody. CD31-immunostaining ensured the presence of representative intratumoral microvasculature. VIR, and membranous and cytoplasmic CC-IR (mCC-IR, cCC-IR) were evaluated using a modified HistoScore (HScore) and subsequently dichotomized into low or high IR expressions. The IR status was correlated with clinico-pathological patient characteristics, including survival and HER2 status.

RESULTS

VIR, mCC-IR, and cCC-IR (HScore > 0) were found in 97.0%, 87.6%, and 95.7% of all GCs. After dichotomization of the HScores, 50.7, 48.8, and 50.3% were classified as VIR-high, mCC-IR-high, and cCC-IR-high, respectively. IR was associated with the Laurén phenotype, tumor localization, local tumor growth, vascular invasion, perineural invasion, tumor budding, mucin phenotype, UICC stage, worse survival, and the HER2 status. On multivariate analysis, VIR status was an independent prognosticator of overall (p = 0.010) and tumor-specific (p = 0.006) patient survival.

CONCLUSIONS

VIR and CC-IR expressions are frequent in GC, biologically significant and even correlate with the HER2 status, opening avenues for novel putative therapeutic interventions in GC.

Obesity, Type-2 Diabetes and Cancer: Mechanistic Insights

Obesity leads to many diseases including hypercholesterolemia, type-2 diabetes, hypertension, cardiovascular disease, and cancer. It is the fastest-growing lethal disease in the Western and developing countries. The link between obesity and cancer is relatively underappreciated among the general population. Obesity represents the number one risk factor for type-2 diabetes and a considerable body of epidemiological studies supports the relationship between type-2 diabetes and many cancers. In this review, we examine the obesity-type-2-diabetes-cancer relationships from a mechanistic perspective, and where appropriate, we highlight potential pharmaceutical and dietary interventions.

Metformin as a geroprotector: experimental and clinical evidence

Apart from being a safe, effective and globally affordable glucose-lowering agent for the treatment of diabetes, metformin has earned much credit in recent years as a potential anti-aging formula. It has been shown to significantly increase lifespan and delay the onset of age-associated decline in several experimental models. The current review summarizes advances in clinical research on the potential role of metformin in the field of geroprotection, highlighting findings from pre-clinical studies on known and putative mechanisms behind its beneficial properties. A growing body of evidence from clinical trials demonstrates that metformin can effectively reduce the risk of many age-related diseases and conditions, including cardiometabolic disorders, neurodegeneration, cancer, chronic inflammation, and frailty. Metformin also holds promise as a drug that could be repurposed for chemoprevention or adjuvant therapy for certain cancer types. Moreover, due to the ability of metformin to induce autophagy by activation of AMPK, it is regarded as a potential hormesis-inducing agent with healthspan-promoting and pro-longevity properties. Long-term intake of metformin is associated with low risk of adverse events; however, well-designed clinical trials are still warranted to enable potential use of this therapeutic agent as a geroprotector.

Differential Expression of IL-10 Gene and Protein in Target Tissues of Rattus Norvegicus Strain Wistar Model Type 2 Diabetes Mellitus (T2DM)

Introduction:

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease caused by insulin resistance. Insulin resistance leads to hyperglycaemia that causes complication such as microangiopathy and macroangiopathy. The immune system of T2DM will be produce IL-10 as an anti-inflammatory cytokine role immune-stimulator and immunosuppressant in the organ system. This present study investigated of IL-10 gene profile and protein expression in the rat organ (Rattus norvegicus) strain Wistar model T2DM.

Material and Methods:

This research was used three of male rats group T2DM and three of male of normal rat as a control. The DNA tissues were isolated, amplified and sequenced by using IL-10 gene primer. The IL-10 protein profile and expression of rat tissues was analyzed using Experion-Pro260 gel and dot blotting using IL-10 antibody.

Results:

This study showed the differential expression of IL-10 gene profile among tissues among normal and T2DM groups. The IL-10 gene sequences, we found eight mutations in brain and twenty-seven mutations on gastric of T2DM group compare with control group, meanwhile there are no mutation in other tissues of both groups. The protein profile of all tissues in both groups was completely diverse as proper. Moreover, the level expression of IL-10 of heart, lung, gastric and kidney of T2DM group was lower than other tissues of both groups.

Conclusion:

This study concludes that T2DM animal model triggering mutation of IL-10 gene sequences of brain and gastric and induced the increasing level expression of IL-10 of ileum, brain and liver.

Corosolic acid reduces 5‑FU chemoresistance in human gastric cancer cells by activating AMPK

5‑Fluorouracil (5‑FU) is one of the most commonly used chemotherapeutic agents for gastric cancer. Resistance to 5‑FU‑based chemotherapy remains the major obstacle in the treatment of gastric cancer. A growing body of evidence has suggested that adenosine monophosphate‑activated protein kinase (AMPK) is pivotal for chemoresistance. However, the mechanism by which AMPK regulates the chemosensitivity of gastric cancer remains unclear. In the present study, how corosolic acid enhanced the chemosensitivity of gastric cancer cells to 5‑FU via AMPK activation was investigated. A 5‑FU‑resistant gastric cancer cell line (SNU‑620/5‑FUR) was established, which had a marked increase in thymidine synthase (TS) expression but reduced AMPK phosphorylation when compared with the parental cell line, SNU‑620. AMPK regulation by 5‑aminoimidazole‑4‑carboxamide ribonucleotide or compound c was revealed to be markedly associated with TS expression and 5‑FU‑resistant cell viability. In addition, corosolic acid activated AMPK, and decreased TS expression and the phosphorylation of mammalian target of rapamycin/4E‑binding protein 1 in a dose‑dependent manner. Corosolic acid treatment significantly reduced cell viability while compound c reversed corosolic acid‑induced cell growth inhibition. The 5‑FU‑resistance sensitization effect of corosolic acid was determined by the synergistic reduction of TS expression and inhibition of cell viability in the presence of 5‑FU. The corosolic acid‑induced AMPK activation was markedly increased by additional 5‑FU treatment, while compound c reversed AMPK phosphorylation. In addition, compound c treatment reversed corosolic acid‑induced apoptotic markers such as capase‑3 and PARP cleavage, and cytochrome c translocation to cytosol, in the presence of 5‑FU. Corosolic acid treatment in the presence of 5‑FU induced an increase in the apoptotic cell population based on flow cytometry analysis. This increase was abolished by compound c. In conclusion, these results implied that corosolic acid may have therapeutic potential to sensitize the resistance of gastric cancer to 5‑FU by activating AMPK.

Risk of gastric cancer development after eradication of Helicobacter pylori

Helicobacter pylori (H. pylori) infection is the most important risk factor for gastric cancer (GC) development through the Correa’s gastric carcinogenesis cascade. However, H. pylori eradication alone does not eliminate GC, as pre-neoplastic lesions (atrophic gastritis, intestinal metaplasia and dysplasia) may have already developed in some patients. It is therefore necessary to identify patients at high-risk for gastric cancer after H. pylori eradication to streamline the management plan. If the patients have not undergone endoscopy with histologic assessment, the identification of certain clinical risk factors and non-invasive testing (serum pepsinogen) can predict the risk of atrophic gastritis. For those with suspected atrophic gastritis, further risk stratification by endoscopy with histologic assessment according to validated histologic staging systems would be advisable. Patients with higher stages may require long-term endoscopic surveillance. Apart from secondary prevention to reduce deaths by diagnosing GC at an early stage, identifying medications that could potentially modify the GC risk would be desirable. The potential roles of a number of medications have been suggested by various studies, including proton pump inhibitors (PPIs), aspirin, statins and metformin. However, there are currently no randomized clinical trials to address the impact of these medications on GC risk after H. pylori eradication. In addition, most of these studies failed to adjust for the effect of concurrent medications on GC risk. Recently, large population-based retrospective cohort studies have shown that PPIs were associated with an increased GC risk after H. pylori eradication, while aspirin was associated with a lower risk. The roles of other agents in reducing GC risk after H. pylori eradication remain to be determined.

Metformin and lung cancer risk in patients with type 2 diabetes mellitus

This study evaluated whether metformin might reduce lung cancer risk. The reimbursement database of the Taiwan's National Health Insurance was used. A sample of 15414 never users and 280159 ever users of metformin (original sample) and a 1:1 matched-pairs of ever and never users (n=15414 in each group, matched sample) were recruited from patients with newly diagnosed type 2 diabetes mellitus during 1999-2005. They were followed until December 31, 2011. Cox regression incorporated with the inverse probability of treatment weighting using propensity score was used to estimate hazard ratios. Results showed that the respective incidence of lung cancer in ever and never users was 173.36 and 292.65 per 100000 person-years in the original sample; and was 211.71 and 292.65, respectively, in the matched sample. The overall hazard ratios (95% confidence intervals) of 0.586 (0.509-0.674) in the original sample and 0.717 (0.584-0.881) in the matched sample suggested a significantly lower risk among metformin users. Hazard ratios comparing the first (<22.60 months), second (22.60-46.67 months) and third (>46.67 months) tertile of cumulative duration of metformin use to never users was 1.163 (1.005-1.348), 0.612 (0.526-0.711) and 0.176 (0.148-0.210), respectively, in the original sample; and was 1.465 (1.131-1.897), 0.758 (0.566-1.016) and 0.228 (1.460-0.357) in the respective tertile of the matched sample. Sensitivity analyses after excluding patients with certain risk factors of cancer and subgroup analyses supported a favorable effect of metformin. In conclusion, metformin use may reduce lung cancer risk in patients with type 2 diabetes mellitus.

Diabetes mellitus and the risk of gastric cancer: a meta-analysis of cohort studies

Studies examining the relationship between diabetes mellitus (DM) and the risk of gastric cancer incidence or gastric cancer mortality have produced inconsistent results. The purpose of this study was to evaluate the evidence regarding the relationship between DM and subsequent gastric cancer incidence or gastric cancer mortality risk on the basis of cohort studies. A systematic search of articles in PubMed, EmBase, the Cochrane Library, and reference lists was conducted to identify relevant literature. Twenty-two cohort studies reporting data on 8,559,861 participants were included in the study. Overall, participants with DM had little or no change in the risk of gastric cancer, or gastric cancer mortality. There was no evidence of difference in the RR for gastric cancer between men and women. Participants with DM had a non-significant trend towards an increased risk of gastric cancer mortality in men. There was no significant difference between men and women for this relationship. Finally, although subgroup analysis suggested DM was associated with a significant impact on gastric cancer incidence and gastric cancer mortality risk in several specific populations, a significance based on gender difference was not observed. In conclusion, DM might increase the risk of gastric cancer in men when the study used standard incidence/mortality ratio as effect estimate. Further, DM were associated with higher risk of gastric cancer mortality in men if the mean age at baseline less than 55.0 years, used RR or HR as effect estimate, the study adjusted smoking or not, and the study not adjusted alcohol drinking.

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.

Pre-clinical effects of metformin and aspirin on the cell lines of different breast cancer subtypes

Background Breast cancer is highly prevalent among women worldwide. It is classified into three main subtypes: estrogen receptor positive (ER+), human epidermal growth factor receptor 2 positive (HER2+), and triple negative breast cancer (TNBC). This study has evaluated the effects of aspirin and metformin, isolated or in a combination, in breast cancer cells of the different subtypes. Methods The breast cancer cell lines MCF-7, MDA-MB-231, and SK-BR-3 were treated with aspirin and/or metformin (0.01 mM - 10 mM); functional in vitro assays were performed. The interactions with the estrogen receptors (ER) were evaluated in silico. Results Metformin (2.5, 5 and 10 mM) altered the morphology and reduced the viability and migration of the ER+ cell line MCF-7, whereas aspirin triggered this effect only at 10 mM. A synergistic effect for the combination of metformin and aspirin (2.5, 5 or 10 mM each) was observed in the TNBC cell subtype MDA-MB-231, according to the evaluation of its viability and colony formation. Partial inhibitory effects were observed for either of the drugs in the HER2+ cell subtype SK-BR-3. The effects of metformin and aspirin partly relied on cyclooxygenase-2 (COX-2) upregulation, without the production of lipoxins. In silico, metformin and aspirin bound to the ERα receptor with the same energy. Conclusion We have provided novel evidence on the mechanisms of action of aspirin and metformin in breast cancer cells, showing favorable outcomes for these drugs in the ER+ and TNBC subtypes.

Obesity, Diabetes and Gastrointestinal Malignancy: The role of Metformin and other Anti-diabetic Therapy

The association between Diabetes and cancer has been known for decades with obesity and insulin resistance being postulated as the main underlying risk factors for both disorders. With rise of the epidemic of obesity in the USA and around the globe, there has been a rise in diabetes that is currently reaching epidemic proportions. Diabetes is known to be associated with increased risk of several types of malignancy including breast, cervical, pancreatic and colon cancer. In this review, we discuss the epidemic of obesity and its consequential epidemic of diabetes highlighting the pathophysiologic mechanisms of increased cancer in the diabetic population. We will then discuss the role of insulin therapy as well as, other antidiabetic medications, particularly metformin that has been to be associated with lower risk as well as better survival with GI malignancies based on several studies including a study that was recently published by our group.