Lower risk of cancer in patients on metformin in comparison with those on sulfonylurea derivatives: results from a large population-based follow-up study

Comparing the effects of biguanides and dipeptidyl peptidase-4 inhibitors on cardio-cerebrovascular outcomes, nephropathy, retinopathy, neuropathy, and treatment costs in diabetic patients

BACKGROUND

Western guidelines often recommend biguanides as the first-line treatment for diabetes. However, dipeptidyl peptidase-4 (DPP-4) inhibitors, alongside biguanides, are increasingly used as the first-line therapy for type 2 diabetes (T2DM) in Japan. However, there have been few studies comparing the effectiveness of biguanides and DPP-4 inhibitors with respect to diabetes-related complications and cardio-cerebrovascular events over the long term, as well as the costs associated.

OBJECTIVE

We aimed to compare the outcomes of patients with T2DM who initiate treatment with a biguanide versus a DPP-4 inhibitor and the long-term costs associated.

METHODS

We performed a cohort study between 2012 and 2021 using a new-user design and the Shizuoka Kokuho database. Patients were included if they were diagnosed with T2DM. The primary outcome was the incidence of cardio-cerebrovascular events or mortality from the initial month of treatment; and the secondary outcomes were the incidences of related complications (nephropathy, renal failure, retinopathy, and peripheral neuropathy) and the daily cost of the drugs used. Individuals who had experienced prior events during the preceding year were excluded, and events within 6 months of the start of the study period were censored. Propensity score matching was performed to compare between two groups.

RESULTS

The matched 1:5 cohort comprised 529 and 2,116 patients who were initially treated with a biguanide or a DPP-4 inhibitor, respectively. Although there were no significant differences in the incidence of cardio-cerebrovascular events or mortality and T2DM-related complications between the two groups (p = 0.139 and p = 0.595), daily biguanide administration was significantly cheaper (mean daily cost for biguanides, 61.1 JPY; for DPP-4 inhibitors, 122.7 JPY; p<0.001).

CONCLUSION

In patients with T2DM who initiate pharmacotherapy, there were no differences in the long-term incidences of cardio-cerebrovascular events or complications associated with biguanide or DPP-4 use, but the former was less costly.

Effect of metformin on incidence, recurrence, and mortality in prostate cancer patients: integrating evidence from real-world studies

PURPOSE

Metformin has been suggested to reduce the risk of cancer. However, previous studies have been inconsistent regarding the relationship between metformin use and the risk of occurrence of prostate cancer (PCa). The purpose of this study was to assess the effect of metformin on clinical outcomes in patients with PCa in a meta-analysis and to explore the possible dose-response relationship.

METHODS

A systematic literature search was conducted in 10 electronic databases and 4 registries. The combined relative risks (RRs) were calculated using a random-effects model with 95% confidence interval (CIs) to assess the effect of metformin on the risk of PCa. Relevant subgroup analyses and sensitivity analyses were performed.

RESULTS

The across studies results show that metformin use associated with lower incidence of PCa (RR: 0.82, 95% CI: 0.74-0.91). Metformin use was also found to reduce PCa recurrence, but the results were not statistically significant (RR: 0.97, 95% CI: 0.81-1.15). Metformin use was not associated with PCa mortality (RR: 0.94, 95% CI: 0.81-1.09). The results of subgroup analyses indicated that the type of study was a cohort study and the population came from both Asia and Europe showed that taking metformin reduced the incidence of PCa. A linear correlation was found between the duration of metformin use and its protective effect.

CONCLUSIONS

This meta-analysis revealed an independent correlation between metformin use and reduced incidence of PCa. Metformin use was not associated with either PCa recurrence rate or mortality. Furthermore, the effect of metformin on PCa incidence was found to be related to duration.

Metformin and other anti-diabetic medication use and breast cancer incidence in the Nurses' Health Studies

We aimed to examine the association between the use of metformin and other anti-diabetic medications and breast cancer incidence within two large prospective cohort studies. We followed 185,181 women who participated in the Nurses' Health Study (NHS; 1994-2016) and the NHSII (1995-2017), with baseline corresponding to the date metformin was approved for type 2 diabetes (T2D) treatment in the US Information on T2D diagnosis, anti-diabetes medications, and other covariates was self-reported at baseline and repeatedly assessed by follow-up questionnaires every 2 years. Breast cancer cases were self-reported and confirmed by medical record review. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between medication use and breast cancer were estimated using Cox proportional hazards regression models, adjusting for breast cancer risk factors. During 3,324,881 person-years of follow-up, we ascertained 9,192 incident invasive breast cancer cases, of which 451 were among women with T2D. Compared with women without T2D (n = 169,263), neither metformin use (HR = 0.97; 95% CI = 0.81-1.15) nor other anti-diabetic medications use (HR = 1.11; 95% CI = 0.90-1.36) associated with significantly lower breast cancer incidence. Among women with T2D (n = 15,918), compared with metformin never users, metformin ever use was not significantly inversely associated with breast cancer (HR = 0.92; 95% CI = 0.74-1.15). Although we observed that past use of metformin was inversely associated with breast cancer in the T2D population (HR = 0.67; 95% CI = 0.48-0.94), current use (HR = 1.01; 95% CI = 0.80-1.27) and longer duration of metformin use were not associated with breast cancer (each 2-year interval: HR = 1.01; 95% CI = 0.95-1.07). Overall, metformin use was not associated with the risk of developing breast cancer among the overall cohort population or among women with T2D.

Does metformin really reduce prostate cancer risk: an up-to-date comprehensive genome-wide analysis

BACKGROUND

The relationship between metformin use and prostate cancer (PCa) risk has yet to be clear despite more than a decade of debate on this topic. Hence, we aimed to investigate the causal role of metformin in reducing PCa risk through an up-to-date comprehensive genome-wide analysis.

METHODS

We employed validated instrument variables of metformin use derived from a prior high-quality study, including five potential targets (AMPK, GCG, GDF15, MCI and MG3). Mendelian randomization (MR) analysis was performed to harmonize genetically predicted metformin use and PCa phenotypes. PCa phenotypes were from two large genome-wide association studies (GWAS), the Prostate Cancer Association Group to Investigate Cancer-Associated Alterations in the Genome (PRACTICAL) and the FinnGen cohort. Seven methods were applied to generate MR results: the inverse variance weighted (IVW), IVW with multiplicative random effects, MR-Egger, MR-Egger (bootstrap), weighted median, simple mode and weighted mode. Strict sensitivity analysis was conducted to satisfy core assumptions of MR design.

RESULTS

We enrolled 32 significant single nucleotide polymorphisms (SNPs) that involved with metformin use. Nearly all targets yielded insignificant primary results (IVW with multiplicative random effects), except that AMPK target posed a positive effect on PCa risk from FinnGen cohort [odds ratio (OR): 6.09, 95% confidence interval (CI): 1.10-33.53, P value: 0.038]. The general effect of metformin use, comprising all 5 targets, also yielded negative results (random-effect meta-analysis with OR: 1.09, 95% CI: 0.76-1.58, P value: 0.637 for PRACTICAL; OR: 2.55, 95% CI: 0.58-11.16, P value: 0.215 for FinnGen). None of the sensitivity analyses provided support for a causal association between metformin use and PCa risk.

CONCLUSION

This up-to-date study did not support the protective role of metformin in reducing PCa risk, considering each target, overall effect, and sensitivity analysis. It is imperative to reflect on the presumed "almighty medicine" and ongoing phase III trials are anticipated to assess the anti-neoplasm effect of metformin.

Recent advances in dietary androgen receptor inhibitors

As a nuclear transcription factor, the androgen receptor (AR) plays a crucial role not only in normal male sexual differentiation and growth of the prostate, but also in benign prostatic hyperplasia, prostatitis, and prostate cancer. Multiple population-based epidemiological studies demonstrated that prostate cancer risk was inversely associated with increased dietary intakes of green tea, soy products, tomato, and so forth. Therefore, this review aimed to summarize the structure and function of AR, and further illustrate the structural basis for antagonistic mechanisms of the currently clinically available antiandrogens. Due to the limitations of these antiandrogens, a series of natural AR inhibitors have been identified from edible plants such as fruits and vegetables, as well as folk medicines, health foods, and nutritional supplements. Hence, this review mainly focused on recent experimental, epidemiological, and clinical studies about natural AR inhibitors, particularly the association between dietary intake of natural antiandrogens and reduced risk of prostatic diseases. Since natural products offer multiple advantages over synthetic antiandrogens, this review may provide a comprehensive and updated overview of dietary-derived AR inhibitors, as well as their potential for the nutritional intervention against prostatic disorders.

Diabetes and the risk of bladder cancer subtypes in men and women: results from the Netherlands Cohort Study

Meta-analyses have shown modest positive associations between diabetes mellitus (DM) and bladder cancer risk, but results are heterogeneous. This might be due to lack of distinction between bladder cancer subtypes, between sexes, and possibly between Type 2 and Type 1 DM (T2DM and T1DM). The relationship of T2DM (and secondarily T1DM) characteristics with risk of bladder cancer subtypes (invasive versus noninvasive) was investigated in the Netherlands Cohort Study. In 1986, 120,852 men and women aged 55-69 years provided information on DM and lifestyle data. After 20.3 years of follow-up, multivariable case-cohort analyses were based on 1020 invasive and 1088 noninvasive bladder cancer cases, and 4267 subcohort members with complete data on DM and confounders. While T2DM was not associated with noninvasive bladder cancer, it was statistically significantly associated with invasive bladder cancer risk: the multivariable-adjusted was HR = 1.57 (95% CI 1.04-2.37), comparing participants with T2DM versus without DM. The association was only significant in women, and women showed a stronger association [HR = 2.19 (95% CI 1.10-4.34)] between T2DM and invasive bladder cancer than men [HR = 1.42 (95% CI 0.88-2.30)]; interaction by sex was nonsignificant. Associations were stronger positive in those whose age at diagnosis of T2DM was 55+ years, and in those diagnosed with T2DM less than five years before baseline. T2DM participants using antidiabetic medication had higher invasive bladder cancer risk than those without DM. Exploratory age-sex-adjusted analyses suggested a positive association between T1DM and invasive bladder cancer, but this was based on few cases. These findings suggest that T2DM and possibly T1DM are positively associated with invasive bladder cancer risk.

Metformin and Hepatocellular Carcinoma Risk Reduction in Diabetic Patients with Chronic Hepatitis C: Fact or Fiction?

BACKGROUND

Patients with chronic hepatitis C (CHC) and concomitant type 2 diabetes mellitus (DM) show a higher risk of developing hepatocellular carcinoma (HCC). Successful antiviral therapy has reduced the incidence of post-therapy HCC, but the presence of DM still represents an unfavourable predictive factor even in cured patients. Metformin (MET) is recommended as a first-line therapy for DM, and its use is associated with a significant reduction in HCC among diabetic patients with chronic liver disease of different etiology, but very few studies specifically address this issue in patients with CHC.

AIM

the aim of this review is to evaluate whether the use of MET induces a significant decrease in HCC in diabetic patients with CHC, treated or untreated with antiviral therapy.

METHODS

A search of PubMed, Medline, Web of Sciences and Embase was conducted for publications evaluating the role of MET in reducing the risk of HCC in patients with DM and CHC, with no language and study type restrictions up to 30 June 2023. Only studies fulfilling the following inclusion criteria were considered: (1) data on the incidence of HCC in the follow-up of diabetic patients with CHC only; (2) follow-up ≥24 months; (3) sufficient data to establish the rate of diabetic patients with CHC treated with metformin or other antidiabetic medications; and (4) data on the type of antiviral treatment and the clinical outcome.

RESULTS

Three studies met the inclusion criteria. A prospective cohort study considering only patients with DM and untreated advanced CHC, or non-responders to interferon (IFN) therapy, showed that the use of MET was associated with a significant decrease in HCC incidence, liver-related death and liver transplants. A recent retrospective study focusing on a large-scale nationwide cohort of patients with CHC in Taiwan successfully treated with IFN-based therapy stratified patients into 3 groups: non-MET users, MET users and non-diabetic patients, with 5-year cumulative rates of HCC of 10.9%, 2.6% and 3.0%, respectively, showing a significantly higher HCC risk in non-MET users compared with MET users and with non-diabetic patients, while it was not significantly different between MET users and non-diabetic patients. In a recent Italian cohort study focusing on 7007 patients with CHC treated and cured with direct-acting antiviral agents (DAAs), a combined effect of DM and MET therapy was found, showing a higher incidence of HCC in diabetic patients not taking MET compared with those without DM and those with DM taking MET.

CONCLUSION

according to the current evidence, the use of MET should be encouraged in diabetic patients with CHC in order to reduce the risk of HCC; however, a well-designed randomized controlled trial is needed to establish the generalizability of the beneficial effects of MET in this particular subset of patients.

Low BMI patients with advanced EGFR mutation-positive NSCLC can get a better outcome from metformin plus EGFR-TKI as first-line therapy: A secondary analysis of a phase 2 randomized clinical trial

Background

The synergistic association between metformin and epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) has been confirmed in in vitro studies. It is still controversial which patients can benefit from metformin plus EGFR-TKIs treatment. Body mass index (BMI) was proved to be independently associated with prolonged progression-free survival (PFS) and overall survival (OS). This study aimed to investigate whether BMI is associated with the synergistic effect of metformin and EGFR-TKIs in advanced EGFR mutation (EGFRm)-positive non-small cell lung cancer (NSCLC) among nondiabetic Asian population.

Methods

We performed a post hoc analysis of a prospective, double-blind phase II randomized clinical trial (COAST, NCT01864681), which enrolled 224 patients without diabetes with treatment-naïve stage IIIB-IV EGFRm NSCLC. We stratified patients into those with a high BMI (≥24 kg/m2) and those with a low BMI (<24 kg/m2) to allow an analysis of the difference in PFS and OS between the two groups. The PFS and OS were analyzed using Kaplan-Meier curves, and the differences between groups were compared using log-rank test.

Results

In the univariate analysis, patients who had a high BMI (n = 56) in the gefitinib + metformin group (n = 28) did not have a better PFS (8.84 months vs. 11.67 months; P = 0.351) or OS (15.58 months vs. 24.36 months; P = 0.095) than those in the gefitinib + placebo group (n = 28). Similar results were also observed in the low-BMI groups. Strikingly, in the metformin plus gefitinib group, patients who had low BMI (n = 69) showed significantly better OS than those with high BMI (24.89 months [95% CI, 20.68 months-not reached] vs. 15.58 months [95% CI, 13.78-31.53 months]; P = 0.007), but this difference was not observed in PFS (10.78 months vs. 8.84 months; P = 0.285).

Conclusions

Our study showed that nondiabetic Asian advanced NSCLC patients with EGFR mutations who have low BMI seem to get better OS from metformin plus EGFR-TKI treatment.

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

OBJECTIVE

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

METHOD

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

RESULT

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

CONCLUSION

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

Targeting lipid metabolism in metastatic prostate cancer

Despite key advances in the treatment of prostate cancer (PCa), a proportion of men have de novo resistance, and all will develop resistance to current therapeutics over time. Aberrant lipid metabolism has long been associated with prostate carcinogenesis and progression, but more recently there has been an explosion of preclinical and clinical data which is informing new clinical trials. This review explores the epidemiological links between obesity and metabolic syndrome and PCa, the evidence for altered circulating lipids in PCa and their potential role as biomarkers, as well as novel therapeutic strategies for targeting lipids in men with PCa, including therapies widely used in cardiovascular disease such as statins, metformin and lifestyle modification, as well as novel targeted agents such as sphingosine kinase inhibitors, DES1 inhibitors and agents targeting FASN and beta oxidation.

Age-related diseases, therapies and gut microbiome: A new frontier for healthy aging

The gut microbiome is undoubtedly a key modulator of human health, which can promote or impair homeostasis throughout life. This is even more relevant in old age, when there is a gradual loss of function in multiple organ systems, related to growth, metabolism, and immunity. Several studies have described changes in the gut microbiome across age groups up to the extreme limits of lifespan, including maladaptations that occur in the context of age-related conditions, such as frailty, neurodegenerative diseases, and cardiometabolic diseases. The gut microbiome can also interact bi-directionally with anti-age-related disease therapies, being affected and in turn influencing their efficacy. In this framework, the development of integrated microbiome-based intervention strategies, aimed at favoring a eubiotic configuration and trajectory, could therefore represent an innovative approach for the promotion of healthy aging and the achievement of longevity.

Effects of metformin and statins on outcomes in men with castration-resistant metastatic prostate cancer: Secondary analysis of COU-AA-301 and COU-AA-302

BACKGROUND

The associations of metformin and statins with overall survival (OS) and prostate specific antigen response rate (PSA-RR) in trials in metastatic castration-resistant prostate cancer remain unclear.

OBJECTIVE

To determine whether metformin or statins ± abiraterone acetate plus prednisone/prednisolone (AAP) influence OS and PSA-RR.

DESIGN, SETTING AND PARTICIPANT

COU-AA-301 and COU-AA-302 patients were stratified by metformin and statin use. Cox proportional hazards models were used to estimate hazards ratio (HR) stratified by concomitant medications, and a random effects model was used to pool HR. We compared PSA-RR using Chi χ² test.

RESULTS

In COU-AA-301-AAP, metformin was associated with improved PSA-RR (41.1% versus 28.6%) but not prolonged OS. In COU-AA-301-placebo-P, there was no association between metformin and prolonged OS or PSA-RR. In COU-AA-302-AAP, metformin was associated with prolonged OS (adjHR 0.69, 95% CI 0.48-0.98) and improved PSA-RR (72.7% versus 60.0%). In COU-AA-302-P, metformin was associated with prolonged OS (adjHR 0.66, 95% CI 0.47-0.93). In pooled analysis, OS was prolonged among those treated with metformin (pooled HR 0.77, 95% CI 0.62-0.95).In COU-AA-301-AAP, statins were associated with an improved OS (adjHR 0.76, 95% CI 0.62-0.93), while there was no difference in COU-AA-301-P. There was no association with statins and OS in either COU-AA-302 groups. When pooling HR, OS was prolonged among those treated with statins (pooled HR 0.78, 95% CI 0.68-0.88).

CONCLUSION

Within the limitations of post-hoc sub-analyses, metformin and statins are associated with a prolonged OS and increased PSA-RR, particularly in combination with AAP.

The role of AMPK-dependent pathways in cellular and molecular mechanisms of metformin: a new perspective for treatment and prevention of diseases

Metformin can suppress gluconeogenesis and reduce blood sugar by activating adenosine monophosphate-activated protein kinase (AMPK) and inducing small heterodimer partner (SHP) expression in the liver cells. The main mechanism of metformin's action is related to its activation of the AMPK enzyme and regulation of the energy balance. AMPK is a heterothermic serine/threonine kinase made of a catalytic alpha subunit and two subunits of beta and a gamma regulator. This enzyme can measure the intracellular ratio of AMP/ATP. If this ratio is high, the amino acid threonine 172 available in its alpha chain would be activated by the phosphorylated liver kinase B1 (LKB1), leading to AMPK activation. Several studies have indicated that apart from its significant role in the reduction of blood glucose level, metformin activates the AMPK enzyme that in turn has various efficient impacts on the regulation of various processes, including controlling inflammatory conditions, altering the differentiation pathway of immune and non-immune cell pathways, and the amelioration of various cancers, liver diseases, inflammatory bowel disease (IBD), kidney diseases, neurological disorders, etc. Metformin's activation of AMPK enables it to control inflammatory conditions, improve oxidative status, regulate the differentiation pathways of various cells, change the pathological process in various diseases, and finally have positive therapeutic effects on them. Due to the activation of AMPK and its role in regulating several subcellular signalling pathways, metformin can be effective in altering the cells' proliferation and differentiation pathways and eventually in the prevention and treatment of certain diseases.

Considerations Regarding Public Use of Longevity Interventions

Public attention and interest for longevity interventions are growing. These can include dietary interventions such as intermittent fasting, physical interventions such as various exercise regimens, or through supplementation of nutraceuticals or administration of pharmaceutics. However, it is unlikely that most interventions identified in model organisms will translate to humans, or that every intervention will benefit each person equally. In the worst case, even detrimental health effects may occur. Therefore, identifying longevity interventions using human data and tracking the aging process in people is of paramount importance as we look towards longevity interventions for the public. In this work, we illustrate how to identify candidate longevity interventions using population data in humans, an approach we have recently employed. We consider metformin as a case-study for potential confounders that influence effectiveness of a longevity intervention, such as lifestyle, sex, genetics, age of administration and the microbiome. Indeed, metformin, like most other longevity interventions, may end up only benefitting a subgroup of individuals. Fortunately, technologies have emerged for tracking the rate of 'biological' aging in individuals, which greatly aids in assessing effectiveness. Recently, we have demonstrated that even wearable devices, accessible to everyone, can be used for this purpose. We therefore propose how to use such approaches to test interventions in the general population. In summary, we advocate that 1) not all interventions will be beneficial for each individual and therefore 2) it is imperative that individuals track their own aging rates to assess healthy aging interventions.

Metformin Treatment Among Men With Diabetes and the Risk of Prostate Cancer: A Population-Based Historical Cohort Study

There is conflicting evidence regarding the association between metformin treatment and prostate cancer risk in diabetic men. We investigated this association in a population-based Israeli cohort of 145,617 men aged 21–89 years with incident diabetes who were followed over the period 2002–2012. We implemented a time-dependent covariate Cox model, using weighted cumulative exposure to relate metformin history to prostate cancer risk, adjusting for use of other glucose-lowering medications, age, ethnicity, and socioeconomic status. To adjust for time-varying glucose control variables, we used inverse probability weighting of a marginal structural model. With 666,553 person-years of follow-up, 1,592 men were diagnosed with prostate cancer. Metformin exposure in the previous year was positively associated with prostate cancer risk (per defined daily dose; without adjustment for glucose control, hazard ratio (HR) = 1.53 (95% confidence interval (CI): 1.19, 1.96); with adjustment, HR = 1.42 (95% CI: 1.04, 1.94)). However, exposure during the previous 2–7 years was negatively associated with risk (without adjustment for glucose control, HR = 0.58 (95% CI: 0.37, 0.93); with adjustment, HR = 0.60 (95% CI: 0.33, 1.09)). These positive and negative associations with previous-year and earlier metformin exposure, respectively, need to be confirmed and better understood.

Effects of Metformin Combined With Antifolates on HepG2 Cell Metabolism and Cellular Proliferation

Hepatocellular carcinoma (HCC), one of the most prevalent types of cancers worldwide, continues to maintain high levels of resistance to standard therapy. As clinical data revealed poor response rates, the need for developing new methods has increased to improve the overall wellbeing of patients with HCC. Furthermore, a growing body of evidence shows that cancer metabolic changes are a key feature of many types of human malignancies. Metabolic reprogramming refers to cancer cells’ ability to change their metabolism in order to meet the increased energy demand caused by continuous growth, rapid proliferation, and other neoplastic cell characteristics. For these reasons, metabolic pathways may become new therapeutic and chemopreventive targets. The aim of this study was to investigate the metabolic alterations associated with metformin (MET), an anti-diabetic agent when combined with two antifolate drugs: trimethoprim (TMP) or methotrexate (MTX), and how metabolic changes within the cancer cell may be used to increase cellular death. In this study, single drugs and combinations were investigated using in vitro assays including cytotoxicity assay (MTT), RT-qPCR, annexin V/PI apoptosis assay, scratch wound assay and Seahorse XF analysis, on a human HCC cell line, HepG2. The cytotoxicity assay showed that the IC₅₀ of MET as single therapy was 44.08 mM that was reduced to 22.73 mM and 29.29 mM when combined with TMP and MTX, respectively. The co-treatment of both drugs increased p53 and Bax apoptotic markers, while decreased the anti-apoptotic marker; Bcl-2. Both combinations increased the percentage of apoptotic cells and halted cancer cell migration when compared to MET alone. Furthermore, both combinations decreased the MET-induced increase in glycolysis, while also inducing mitochondrial damage, altering cancer cell bioenergetics. These findings provide an exciting insight into the anti-proliferative and apoptotic effects of MET and anti-folates on HepG2 cells, and how in combination, may potentially combat the aggressiveness of HCC.

Impact of metformin use on risk and mortality of hepatocellular carcinoma in diabetes mellitus

BACKGROUND

The views regarding the associations between metformin use and hepatocellular carcinoma (HCC) among diabetes mellitus (DM) patients are divisive. Thus we summarized all available published studies evaluating the relationship between metformin therapy and HCC survival and risk, and aim to conduct an updated meta-analysis study to more accurately clarify the association.

METHODS

We searched for articles regarding impact of metformin use on risk and mortality of HCC in DM and published before April 2021 in databases (PubMed and Web of Science). We used STATA 12.0 software to compute odds ratios (ORs)/relative risks (RRs) or hazard ratios (HRs) and their 95% confidence intervals (CIs) to generate a computed effect size and 95% CI.

RESULTS

The present study showed that metformin use was associated with a decreased risk of HCC in DM with a random effects model (OR/RR = 0.59, 95% CI 0.51-0.68, I2 = 96.5%, p < 0.001). In addition, the study indicated that metformin use was associated with a decreased all-cause mortality of HCC in DM with a random effects model (HR = 0.74, 95% CI 0.66-0.83, I2 = 49.6%, p = 0.037).

CONCLUSION

In conclusion, our studies support that the use of metformin in DM patients is significantly associated with reduced risk and all-cause mortality of HCC. And more prospective studies focusing on the metformin therapy as a protective factor for HCC are needed to verify the accuracy of the findings.

Antidiabetic Medications and the Risk of Prostate Cancer in Patients with Diabetes Mellitus: A Systematic Review and Meta-analysis

BACKGROUND

Antidiabetic medications (ADMs) may modify prostate cancer (PCa) risk in patients with diabetes mellitus (DM). Accordingly, the current study assessed the possible associations between ADMs and the risk of PCa in diabetics.

METHODS

A systematic literature search (PubMed, Embase and Cochrane Library) identified studies evaluating the associations between ADMs and incidence of PCa. A meta-analysis followed PRISMA was performed using odds ratio (OR) with 95% confidence interval (CI) as effect measures.

RESULTS

In total of 47 studies involving 3,094,152 patients with diabetes were included. Results of meta-analysis of the observational studies suggested no significant association between metformin, thiazolidinediones, sulfonylureas, insulin or dipeptidyl peptidase-4 inhibitors administration and the risk of PCa (All p-values > 0.05). Separate analysis of randomized controlled trials (RCTs) revealed a significant reduction in PCa risk with thiazolidinediones (OR = 0.55, p = 0.04) or glucagon-like peptide-1 receptor agonists (GLP-1RA) administration (OR = 0.53, p = 0.006), whereas no significant association was found in SGLT2 inhibitors (p = 0.3).

CONCLUSION

Thiazolidinediones or GLP-1RA administration may have benefits in PCa based on RCTs, however, further research is needed to confirm these findings.

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.

Prevention of NAFLD-associated HCC: Role of lifestyle and chemoprevention

In many countries worldwide, the burden of hepatocellular carcinoma (HCC) associated with non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) is increasing. Preventive strategies are needed to counteract this trend. In this review, we provide an overview of the evidence on preventive strategies in NAFLD-associated HCC. We consider the impact of lifestyle factors such as weight loss, physical activity, smoking, dietary patterns and food items, including coffee and alcohol, on both HCC and NAFLD/NASH. Furthermore, evidence on chemopreventive treatments, including aspirin, antidiabetic treatments and statins is summarised. The role of adjuvant therapies for tertiary prevention of HCC is briefly reviewed.

Is metformin use associated with a reduced risk of oesophageal cancer? A systematic review and meta-analysis

OBJECTIVES

Studies on the association between metformin use and the risk of oesophageal cancer (OC) have generated controversial findings. This updated meta-analysis was conducted to reassess the effects of metformin on OC.

METHODS

A comprehensive search strategy was conducted to select relevant studies from origination to February 2021. Heterogeneity was evaluated through the Q test and I² statistics. HRs and 95% CIs were pooled through either random-effect or fixed-effect models. Meta-regression, subgroup analyses, sensitivity analysis and publication bias diagnosis were also performed.

RESULTS

Seven studies with 5 426 343 subjects were included. Metformin use was associated with reduced risk of OC (HR=0.69, 95% CI 0.54 to 0.87, p<0.001). Sensitivity analysis suggested that the results were relatively stable.

CONCLUSION

Metformin is associated with a reduced risk of OC. More well-designed studies are still needed to further elaborate on these associations.

PROSPERO REGISTRATION NUMBER

CRD42021237127.

Positive effect of metformin treatment in colorectal cancer patients with type 2 diabetes: national cohort study

We aimed to estimate colorectal cancer risk in patients with type 2 diabetes mellitus (T2DM) using metformin. Patients with colorectal cancer and diabetes from 2000 to 2012 were identified form Lithuanian Cancer Registry and the National Health Insurance Fund database. Standardized incidence ratios (SIRs) for colorectal cancers as a ratio of observed number of cancer cases in people with diabetes to the expected number of cancer cases in the underlying general population was calculated. We analysed 111 109 patients with diabetes. Overall, 1213 colorectal cancers were observed versus 954.91 expected within a period of observation entailing an SIR of 1.27 [95% confidence interval (CI): 1.20-1.34]. Significantly higher risk of colorectal cancer was found both in male and female patients with diabetes in all age groups. Higher risk was found for both colon and rectum cancers 1.36 (95% CI: 1.27-1.46) and 1.11 (95% CI: 1.01-1.22), respectively. There were no differences in risk over time since initial diabetes diagnosis. Never-users of metformin had twice higher risk of colorectal cancer compared to general population (SIR: 2.14, 95% CI: 1.95-2.35). Among metformin users, risk was lover (SIR: 1.47, 95% CI: 1.36-1.58) and colorectal cancer risk decreased with increasing cumulative dose of metformin (P < 0.001). Patients with T2DM had increased risk of colorectal cancer compared with the general Lithuanian population. Decreasing colorectal cancer risk with increasing cumulative dose of metformin indicates that metformin may be a protective agent for colorectal cancer development.

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.

Metformin in the prevention of hepatocellular carcinoma in diabetic patients: A systematic review

.: Preventive effect of metformin in hepatocellular carcinoma (HCC) is not entirely clear. We aimed to evaluate the use of metformin as a protective factor of HCC in diabetic patients. .: We carried out an electronic search on PUBMED/MEDLINE, Web of Science and LILACS databases, with no limit of date, from April 2017 to January 2019. Eligible studies included cohort and case-control studies. We adressed data about the use of metformin on the risk of HCC development. Two independent reviewers extracted the data. We evaluated the quality of studies by using the Newcastle-Ottawa scale and carried out a meta-analysis using random-effects models. .: The electronic searches identified 747 studies. After reading abstracts and titles, we excluded 327 duplicated papers and 383 irrelevant references. Eight studies were selected; four case-control and four cohort studies. All studies have observed that the therapy with metformin was associated with a lower risk of HCC, compared with non-metformin therapy. Five articles reported that patients treated with insulin, or insulin secretagogues, presented increased risk of HCC compared to those treated with metformin. One study found that not only statin but also aspirin reduced the risk of HCC, if combined with metformin. A meta-analysis, using the case-control studies, found a combined Odds Ratio of 0.468; 95% CI 0.275-0.799 for the association between HCC and the use of metformin. .: The use of metformin was associated with a reduced risk of HCC, and it may be a relevant factor for preventing HCC in diabetic patients.

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.

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.

Endocrinology of the Aging Prostate: Current Concepts

Benign prostate hyperplasia (BPH), one of the most common diseases in older men, adversely affects quality-of-life due to the presence of low urinary tract symptoms (LUTS). Numerous data support the presence of an association between BPH-related LUTS (BPH-LUTS) and metabolic syndrome (MetS). Whether hormonal changes occurring in MetS play a role in the pathogenesis of BPH-LUTS is a debated issue. Therefore, this article aimed to systematically review the impact of hormonal changes that occur during aging on the prostate, including the role of sex hormones, insulin-like growth factor 1, thyroid hormones, and insulin. The possible explanatory mechanisms of the association between BPH-LUTS and MetS are also discussed. In particular, the presence of a male polycystic ovarian syndrome (PCOS)-equivalent may represent a possible hypothesis to support this link. Male PCOS-equivalent has been defined as an endocrine syndrome with a metabolic background, which predisposes to the development of type II diabetes mellitus, cardiovascular diseases, prostate cancer, BPH and prostatitis in old age. Its early identification would help prevent the onset of these long-term complications.

Current Status and Application of Metformin for Prostate Cancer: A Comprehensive Review

Metformin, an oral biguanide used for first-line treatment of type 2 diabetes mellitus, has attracted attention for its anti-proliferative and anti-cancer effects in several solid tumors, including prostate cancer (PCa). Liver kinase B1 (LKB1) and adenosine monophosphate-activated protein kinase (AMPK) activation, inhibition of the mammalian target of rapamycin (mTOR) activity and protein synthesis, induction of apoptosis and autophagy by p53 and p21, and decreased blood insulin level have been suggested as direct anti-cancer mechanisms of metformin. Research has shown that PCa development and progression are associated with metabolic syndrome and its components. Therefore, reduction in the risk of PCa and improvement in survival in metformin users may be the results of the direct anti-cancer mechanisms of the drug or the secondary effects from improvement of metabolic syndrome. In contrast, some research has suggested that there is no association between metformin use and PCa incidence or survival. In this comprehensive review, we summarize updated evidence on the relationship between metformin use and oncological effects in patients with PCa. We also highlight ongoing clinical trials evaluating metformin as an adjuvant therapy in novel drug combinations in various disease settings.

Metformin modulates oncogenic expression of HOTAIR gene via promoter methylation and reverses epithelial-mesenchymal transition in MDA-MB-231 cells

Epithelial-mesenchymal transition (EMT) is a biological event, which critically regulates migration and invasion of cancer cells. EMT is regulated by several protein and nonprotein factors (such as noncoding RNAs). HOTAIR is an oncogenic long noncoding RNA that stimulates EMT in cancers. In the current study, we investigated the effect of metformin on EMT behavior and HOTAIR expression in MDA-MB-231 breast cancer cells. The minimal effective concentrations of metformin (10 and 20 mM) were obtained by the MTT test. Cell migration and invasion in the metformin-containing medium were assayed in the scratch assay and transwell test. Meaningful decreases in both cell migration and invasion were observed in the presence of metformin. Vimentin, snail, β-catenin, and HOTAIR transcripts were quantified by real-time polymerase chain reaction (PCR). Reduction in the expression of vimentin, β-catenin, and HOTAIR was detected as the result of metformin treatment, but the snail showed a constant expression. Western blottingrevealed the downregulation of vimentin and β-catenin proteins. HOTAIR promoter methylation pattern was also investigated in metformin-exposed cells using bisulfite sequencing PCR which the result showed differences in the methylation profile of CpG islands between the treated and untreated cells. In conclusion, metformin modulated oncogenic expression of the HOTAIR gene in the MDA-MB-231 cells. This downregulation was associated with the modification of promoter methylation patterns. Since HOTAIR induces EMT in breast cancer, HOTAIR decline might be one of the mechanisms by which metformin reverses EMT.

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.

Relationship between metformin therapy and risk of colorectal cancer in patients with diabetes mellitus: a meta-analysis

OBJECTIVE

At present, there are many studies on metformin and the risk of colorectal cancer in patients with diabetes, but the conclusions are contradictory. Our aim is to comprehensively collect the published literature and systematically evaluate the relationship between metformin and the risk of colorectal cancer in patients with diabetes.

METHODS

We systematically searched the MEDLINE, EMBASE, and CENTRAL databases up to March 2020. We adopted adjusted estimates and their 95% confidence intervals (CI) to calculate summary effect estimates using either a fixed-effects or a random-effects model.

RESULTS

A total of 17 articles were included in this study, with a total of 1,092,074 patients with diabetes. Meta-analysis of observational studies showed that metformin treatment could significantly reduce the incidence of colorectal cancer in diabetic patients (adjusted RR = 0.884, 95%CI = 0.829-0.943), and there was heterogeneity between studies (p = 0.013, I² = 47.9%). Subgroup analysis showed that metformin treatment was significantly associated with a significantly reduced risk of colorectal cancer in diabetics in America and Europe (adjusted RR = 0.852, 95%CI = 0.786-0.924; adjusted RR = 0.900, 95%CI = 0.845-0.958). Patients with diabetes treated with metformin had a significantly lower risk of colorectal cancer compared with patients who had never been treated with metformin or sulfonamide monotherapy (adjusted RR = 0.863, 95%CI = 0.776-0.960; adjusted RR = 0.911, 95%CI = 0.882-0.941).

CONCLUSIONS

Metformin therapy is associated with a significantly reduced risk of colorectal disease in patients with diabetes, and it is necessary to conduct larger, more standardized clinical studies to verify this conclusion.

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.

Selenium-binding protein 1 alters energy metabolism in prostate cancer cells

OBJECTIVE

The broad goal of the research described in this study was to investigate the contributions of selenium-binding protein 1 (SBP1) loss in prostate cancer development and outcome.

METHODS

SBP1 levels were altered in prostate cancer cell lines and the consequences on oxygen consumption, expression of proteins associated with energy metabolism, and cellular transformation and migration were investigated. The effects of exposing cells to the SBP1 reaction products, H₂ O₂ and H₂ S were also assessed. In silico analyses identified potential HNF4α binding sites within the SBP1 promoter region and this was investigated using an inhibitor specific for that transcription factor.

RESULTS

Using in silico analyses, it was determined that the promoter region of SBP1 contains putative binding sites for the HNF4α transcription factor. The potential for HNF4α to regulate SBP1 expression was supported by data indicating that HNF4α inhibition resulted in a dose-response increase in the levels of SBP1 messenger RNA and protein, identifying HNF4α as a novel negative regulator of SBP1 expression in prostate cancer cells. The consequences of altering the levels of SBP1 were investigated by ectopically expressing SBP1 in PC-3 prostate cancer cells, where SBP1 expression attenuated anchorage-independent cellular growth and migration in culture, both properties associated with transformation. SBP1 overexpression reduced oxygen consumption in these cells and increased the activation of AMP-activated protein kinase (AMPK), a major regulator of energy homeostasis. In addition, the reaction products of SBP1, H₂ O₂ , and H₂ S also activated AMPK.

CONCLUSIONS

Based on the obtained data, it is hypothesized that SBP1 negatively regulates oxidative phosphorylation (OXPHOS) in the healthy prostate cells by the production of H₂ O₂ and H₂ S and consequential activation of AMPK. The reduction of SBP1 levels in prostate cancer can occur due to increased binding of HNF4α, acting as a transcriptional inhibitor to the SBP1 promoter. Consequently, there is a reduction in H₂ O₂ and H₂ S-mediated signaling, inhibition of AMPK, and stimulation of OXPHOS and building blocks of biomolecules needed for tumor growth and progression. Other effects of SBP1 loss in tumor cells remain to be discovered.

Repurposing old drugs to fight multidrug resistant cancers

Overcoming multidrug resistance represents a major challenge for cancer treatment. In the search for new chemotherapeutics to treat malignant diseases, drug repurposing gained a tremendous interest during the past years. Repositioning candidates have often emerged through several stages of clinical drug development, and may even be marketed, thus attracting the attention and interest of pharmaceutical companies as well as regulatory agencies. Typically, drug repositioning has been serendipitous, using undesired side effects of small molecule drugs to exploit new disease indications. As bioinformatics gain increasing popularity as an integral component of drug discovery, more rational approaches are needed. Herein, we show some practical examples of in silico approaches such as pharmacophore modelling, as well as pharmacophore- and docking-based virtual screening for a fast and cost-effective repurposing of small molecule drugs against multidrug resistant cancers. We provide a timely and comprehensive overview of compounds with considerable potential to be repositioned for cancer therapeutics. These drugs are from diverse chemotherapeutic classes. We emphasize the scope and limitations of anthelmintics, antibiotics, antifungals, antivirals, antimalarials, antihypertensives, psychopharmaceuticals and antidiabetics that have shown extensive immunomodulatory, antiproliferative, pro-apoptotic, and antimetastatic potential. These drugs, either used alone or in combination with existing anticancer chemotherapeutics, represent strong candidates to prevent or overcome drug resistance. We particularly focus on outcomes and future perspectives of drug repositioning for the treatment of multidrug resistant tumors and discuss current possibilities and limitations of preclinical and clinical investigations.

Metformin and colorectal cancer: a systematic review, meta-analysis and meta-regression

PURPOSE

Metformin may have a role in reducing the incidence of colorectal cancer (CRC) and improving survival outcome. This meta-analysis explored the effect of metformin use on colorectal adenoma and cancer incidence, and colorectal oncological outcomes.

METHODS

A database search was conducted on Medline, Embase and CNKI for studies comparing metformin vs. non-metformin users, metformin users vs. non-diabetics and metformin users vs. diabetics with diet-only treatment. Meta-analysis was done with DerSimonian and Laird with risk ratios (RR), and hazard ratios (HR) for survival outcomes.

RESULTS

We included 58 studies and summarized incidences of colorectal adenoma and cancer, as well as cancer survival outcomes. Metformin users had a significant lower incidence of colorectal adenoma (RR 0.77, CI 0.67-0.88, p < 0.001), advanced adenoma (0.61, CI 0.42-0.88, p = 0.008) and CRC (RR 0.76, CI 0.69-0.84, p < 0.001) respectively compared with non-metformin users. Overall survival (HR 0.6, CI 0.53-0.67, p < 0.001) and CRC-specific survival (HR 0.66, CI 0.59-0.74, p < 0.001) were higher among metformin users compared with non-metformin users. Further analysis on overall survival of metastatic CRC patients revealed significantly higher survival rates in metformin users (HR 0.77, CI 0.68-0.87, p < 0.001).

CONCLUSION

This meta-analysis showed that metformin use significantly reduces colorectal adenoma and cancer incidence and improves colorectal cancer outcomes.

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.

Association between metformin medication, genetic variation and prostate cancer risk

BACKGROUND

The relationship between metformin use and prostate cancer risk remains controversial. Genetic variation in metformin metabolism pathways appears to modify metformin glycemic control and the protective association with some cancers. However, no studies to date have examined this pharmacogenetic interaction and prostate cancer chemoprevention.

METHODS

Clinical data and germline DNA were collected from our prostate biopsy database between 1996 and 2014. In addition to a genome-wide association study (GWAS), 27 single nucleotide polymorphisms (SNPs) implicated in metformin metabolism were included on a custom SNP array. Associations between metformin use and risk of high-grade (Grade Group ≥ 2) and overall prostate cancer were explored using a case-control design. Interaction between the candidate/GWAS SNPs and the metformin-cancer association was explored using a case-only design.

RESULTS

Among 3481 men, 132 (4%) were taking metformin at diagnosis. Metformin users were older, more likely non-Caucasian, and had higher body mass index, Gleason score, and number of positive cores. Overall, 2061 (59%) were diagnosed with prostate cancer, of which 922 (45%) were high-grade. After adjusting for baseline characteristics, metformin use was associated with higher risk of high-grade prostate cancer (OR = 1.76, 95% CI 1.1-2.9, p = 0.02) and overall prostate cancer (OR = 1.77, 95% CI 1.1-2.9, p = 0.03). None of the 27 candidate SNPs in metformin metabolic pathways had significant interaction with the metformin-cancer association. Among the GWAS SNPs, one SNP (rs149137006) had genome-wide significant interaction with metformin for high-grade prostate cancer, and another, rs115071742, for overall prostate cancer. They were intronic and intergenic SNPs, respectively, with largely uncharacterized roles in prostate cancer chemoprevention.

CONCLUSIONS

In our cohort, metformin use was associated with increased risk of being diagnosed with prostate cancer. While SNPs involved in metformin metabolism did not have modifying effects on the association with disease risk, one intronic and one intergenic SNP from the GWAS study did, and these require further study.

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.

Effect of metformin on the risk of prostate cancer in patients with type 2 diabetes by considering different confounding factors: a meta-analysis of observational studies

Preclinical studies have suggested the antitumorigenic properties of metformin on prostate cancer; results from epidemiological studies remain contradictory. We aim to investigate the evidence of metformin and the risk of prostate cancer. PubMed, Embase, Cochrane Library, and Web of Science databases were searched for eligible studies. Meta-analyses were carried out using the most fully adjusted hazard ratios and the corresponding 95% confidence intervals. Eighteen cohort studies and six case-control studies representing 2 009 504 male patients with type 2 diabetes mellitus were identified. The pooled HR of prostate cancer for metformin therapy was 0.97 (0.84-1.12) in case-control studies and 0.94 (0.79-1.12) in cohort studies, respectively. In cohort studies, we found that there was a modest association in studies with samples from Europe, but not in studies with samples from North America, Asia, and Oceania. In addition, metformin showed a slightly protective effect compared with sulfonylurea, but not insulin and other comparators. Meta-regression analyses found that obesity and prostate-specific antigen adjustment in statistical models may be the sources of heterogeneity. However, there were no significant differences in subgroups stratified by time-related biases, analytical approaches, types of risk estimates, study quality, publication year, and whether adjusted for smoking, alcohol abuse, hemoglobin A1c, diabetes duration, and other confounding factors. Our study showed that metformin therapy was not associated with the risk of prostate cancer in patients with type 2 diabetes mellitus. However, exploratory analyses suggest that metformin use may be protective in a certain subgroup of patients.

Association Between Metformin Use and Risk of Esophageal Squamous Cell Carcinoma in a Population-Based Cohort Study

OBJECTIVES

Esophageal cancer is a highly fatal malignant neoplasm, with 2 etiologically different histological types. A large prospective study is expected to elucidate the specific risk of the 90% subtype of esophageal cancer, esophageal squamous cell carcinoma (ESCC), with metformin therapy. This study aims to determine the association between metformin use and incident ESCC risk.

METHODS

This was a nationwide population-based prospective cohort study conducted in Sweden in 2005-2015. Among 8.4 million participants identified in the cohort, 411,603 (5%) were metformin users. The users were compared with 10 times as many frequency-matched nonusers of metformin (n = 4,116,030) by age and sex. Metformin use was treated as a time-varying variate, and multivariable cause-specific proportional hazards model was used to calculate hazard ratios (HR) with 95% confidence intervals (CI) for ESCC, adjusted for age, sex, calendar year, residence area, tobacco smoking, alcohol overconsumption, and use of nonsteroidal anti-inflammatory drugs or statins.

RESULTS

The incidence rates of ESCC were 3.5 per 100,000 person-years among the metformin users and 5.3 per 100,000 person-years in the nonusers. Metformin users overall were at a decreased risk of ESCC compared with nonusers (HR 0.68, 95% CI 0.54-0.85). The decrease in risk was more pronounced in new metformin users (HR 0.44, 95% CI 0.28-0.64) and participants aged 60-69 years (HR 0.45, 95% CI 0.31-0.66).

DISCUSSION

Metformin use decreases the risk of developing ESCC.

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.

The role of pyruvate kinase M2 in anticancer therapeutic treatments

Cancer cells are characterized by a high glycolytic rate, which leads to energy regeneration and anabolic metabolism; a consequence of this is the abnormal expression of pyruvate kinase isoenzyme M2 (PKM2). Multiple studies have demonstrated that the expression levels of PKM2 are upregulated in numerous cancer types. Consequently, the mechanism of action of certain anticancer drugs is to downregulate PKM2 expression, indicating the significance of PKM2 in a chemotherapeutic setting. Furthermore, it has previously been highlighted that the downregulation of PKM2 expression, using either inhibitors or short interfering RNA, enhances the anticancer effect exerted by THP treatment on bladder cancer cells, both in vitro and in vivo. The present review summarizes the detailed mechanisms and therapeutic relevance of anticancer drugs that inhibit PKM2 expression. In addition, the relationship between PKM2 expression levels and drug resistance were explored. Finally, future directions, such as the targeting of PKM2 as a strategy to explore novel anticancer agents, were suggested. The current review explored and highlighted the important role of PKM2 in anticancer treatments.