The association between metformin use and colorectal cancer survival among patients with diabetes mellitus: An updated meta-analysis

Knowledge mapping of metformin use on cancers: a bibliometric analysis (2013-2023)

There is substantial evidence from clinical and preclinical studies suggesting an association between metformin use and a reduced risk of cancer. However, the effects of metformin use on cancers have not yet been subjected to bibliometric analysis. The goal of this study was to explore the potential effects of metformin use on cancers and to conduct a comprehensive assessment of research hotspots related to the use of metformin on cancers. The results of the literature analysis were visualized using various tools such as Adobe Illustrator CC 2018, VOSviewer, CiteSpace, and the R package "bibliometric." The average annual publications from 2013 to 2023 was 372. In terms of journals and co-cited journals, a total of 1,064 journals published 1958 papers, and Oncotarget published the highest number of papers (n = 153, 7.81%), while Cancer Research (Co-citation = 5,125) was the most frequently cited journal. A total of 25,665 authors participated in the research on metformin use on cancers. Metformin has demonstrated improved outcomes in various types of cancer, including breast cancer (BC), lung cancer (LC), colorectal cancer (CRC), prostate cancer (PC), and pancreatic cancer. This bibliometric analysis reviews the current literature on the clinical data on metformin use on cancers and describes the preclinical evidence illustrating the potential mechanisms of metformin use on various cancers directly or indirectly.

The Association of Metformin, Other Antidiabetic Medications and Statins on the Prognosis of Rectal Cancer in Patients with Type 2 Diabetes: A Retrospective Cohort Study

Metformin and statin use have been associated with an improved prognosis for colorectal cancer in persons with type 2 diabetes (T2D). Data regarding rectal cancer (RC) have been inconclusive; therefore, we investigated the issue with high-quality data and a robust study design. We identified 1271 eligible patients with T2D and incident RC between 1998 and 2011 from the Diabetes in Finland (FinDM) database. Cox models were fitted for cause-specific mortality rates to obtain adjusted estimates of the hazard ratios (HR) with 95% confidence intervals (CI) in relation to use of antidiabetic medication (ADM) and statins before the RC diagnosis and for post-diagnostic use in a time-dependent exposure manner. No sufficient evidence was found for either pre- or post-diagnostic metformin use and RC mortality (HR 0.96, 95% CI 0.67–1.38, and 0.70, 95% CI 0.45–1.10, respectively) when compared to other oral ADMs. Both pre- and post-diagnostic statin use appeared to be inversely associated with mortality from RC (HR 0.77 95% CI 0.63–0.94, and 0.57, 95% CI 0.42–0.78, respectively). Our study was inconclusive as to the association of metformin use with the prognosis of RC, but statin use was found to predict reduced mortality, both from RC and from other causes of death in persons with T2D.

The Association of Metformin, Other Antidiabetic Medications, and Statins With the Prognosis of Colon Cancer in Patients With Type 2 Diabetes: A Retrospective Cohort Study

BACKGROUND

Use of metformin and statins have been associated with improved prognosis of colon cancer (CC) in patients with type 2 diabetes (T2D). We examined the survival from CC in relation to the use of metformin, other oral antidiabetic medications (ADM), insulin, and statins in T2D patients.

MATERIALS AND METHODS

A cohort (n = 2252) of persons with pre-existing T2D diagnosed with incident CC between 1998 and 2011 was identified from several Finnish registers. Cox models were fitted for cause-specific mortality rates to obtain adjusted estimates of the hazard ratios (HR) with 95% confidence intervals (CI) in relation to use of ADM and statins before the CC diagnosis. Cox models were also fitted for mortality in relation to post-diagnostic use of the medications treating these as time-dependent exposures, and starting follow-up 1 year after the CC diagnosis.

RESULTS

Pre- and post-diagnostic metformin use was weakly associated with the risk of CC-related death (HR .75; 95% CI .58-.99, and HR .78; 95% CI .54-1.14, respectively) compared to the use of other oral ADMs. Pre- and post-diagnostic statin use predicted a reduced risk of CC-related death (HR .83; 95% CI .71- .98, and HR .69; 95% CI .54-.89, respectively).

CONCLUSION

Additional evidence was found for use of statins being associated with an improved survival from CC in patients with pre-existing T2D, but for metformin use the evidence was weaker.

Metformin treatment response is dependent on glucose growth conditions and metabolic phenotype in colorectal cancer cells

Cancer cells exhibit altered metabolism, a phenomenon described a century ago by Otto Warburg. However, metabolic drug targeting is considered an underutilized and poorly understood area of cancer therapy. Metformin, a metabolic drug commonly used to treat type 2 diabetes, has been associated with lower cancer incidence, although studies are inconclusive concerning effectiveness of the drug in treatment or cancer prevention. The aim of this study was to determine how glucose concentration influences cancer cells' response to metformin, highlighting why metformin studies are inconsistent. We used two colorectal cancer cell lines with different growth rates and clinically achievable metformin concentrations. We found that fast growing SW948 are more glycolytic in terms of metabolism, while the slower growing SW1116 are reliant on mitochondrial respiration. Both cell lines show inhibitory growth after metformin treatment under physiological glucose conditions, but not in high glucose conditions. Furthermore, SW1116 converges with SW948 at a more glycolytic phenotype after metformin treatment. This metabolic shift is supported by changed GLUT1 expression. Thus, cells having different metabolic phenotypes, show a clear differential response to metformin treatment based on glucose concentration. This demonstrates the importance of growth conditions for experiments or clinical studies involving metabolic drugs such as metformin.

Metformin alleviates breast cancer through targeting high-mobility group AT-hook 2

BACKGROUND

As a classic oral drug used in diabetic patients, metformin has exhibited an anticancer role in many types of cancers in recent years. Here, we aimed to investigate the role of metformin in the growth of breast cancer and its novel targets.

METHODS

A cell viability assay was utilized to examine the inhibitory effect of metformin on proliferation of breast cancer cells. Western blotting and RT-PCR assays were used to detect the regulation of metformin on the expression of oncogenic HMGA2. The luciferase reporter vector of HMGA2 promoter was constructed. A luciferase reporter gene assay was performed to analyze the effect of metformin on HMGA2 promoter activity in breast cancer cells. Chromatin immunoprecipitation (ChIP) assay was performed to show the binding of Sp1 to HMGA2 promoter in breast cancer cells with or without metformin treatment. The function of metformin-regulated HMGA2 in breast cancer growth was tested using a cell viability assay.

RESULTS

Cell proliferation was obviously inhibited in breast cancer cells treated with different concentrations of metformin. The level of mRNA and protein of HMGA2 was significantly reduced by metformin in the cells. Mechanistically, metformin was able to inactivate the HMGA2 promoter through downregulating transcription factor Sp1 in the cells. In terms of function, treatment with metformin suppressed the proliferation of breast cancer cells and overexpressed HMGA2 reversed the inhibition of cell proliferation mediated by metformin.

CONCLUSION

Metformin resists the growth of breast cancer through targeting Sp1/HMGA2 signal.

Effects of metformin and phenformin on apoptosis and epithelial-mesenchymal transition in chemoresistant rectal cancer

Recurrence and chemoresistance in colorectal cancer remain important issues for patients treated with conventional therapeutics. Metformin and phenformin, previously used in the treatment of diabetes, have been shown to have anticancer effects in various cancers, including breast, lung and prostate cancers. However, their molecular mechanisms are still unclear. In this study, we examined the effects of these drugs in chemoresistant rectal cancer cell lines. We found that SW837 and SW1463 rectal cancer cells were more resistant to ionizing radiation and 5‐fluorouracil than HCT116 and LS513 colon cancer cells. In addition, metformin and phenformin increased the sensitivity of these cell lines by inhibiting cell proliferation, suppressing clonogenic ability and increasing apoptotic cell death in rectal cancer cells. Signal transducer and activator of transcription 3 and transforming growth factor‐β/Smad signaling pathways were more activated in rectal cancer cells, and inhibition of signal transducer and activator of transcription 3 expression using an inhibitor or siRNA sensitized rectal cancer cells to chemoresistant by inhibition of the expression of antiapoptotic proteins, such as X‐linked inhibitor of apoptosis, survivin and cellular inhibitor of apoptosis protein 1. Moreover, metformin and phenformin inhibited cell migration and invasion by suppression of transforming growth factor β receptor 2‐mediated Snail and Twist expression in rectal cancer cells. Therefore, metformin and phenformin may represent a novel strategy for the treatment of chemoresistant rectal cancer by targeting signal transducer and activator of transcription 3 and transforming growth factor‐β/Smad signaling.

Diabetes Mellitus and Colon Carcinogenesis: Expectation for Inhibition of Colon Carcinogenesis by Oral Hypoglycemic Drugs

The global deaths due to colorectal cancer and diabetes mellitus have increased by 57% and 90%, respectively. The relationship between various cancers and diabetes mellitus has been shown in multiple epidemiological studies. Hence, better management of diabetes mellitus is expected to reduce the risk of various cancers. This review focuses on colorectal cancer and aims to summarize recent findings on the antitumor effects of various oral hypoglycemic drugs on colorectal cancer and their estimated mechanisms. Of the seven classes of oral hypoglycemic agents, only metformin was found to have suppressive effects on colorectal cancer in both clinical and basic research. Clinical and basic researches on suppressing effects of glinides, dipeptidyl peptidase-4 inhibitors, thiazolidinedione, α-glucosidase inhibitors, and sodium glucose cotransporter-2 inhibitors against colon carcinogenesis have been insufficient and have not arrived at any conclusion. Therefore, further research regarding these agents is warranted. In addition, the suppressive effects of these agents in healthy subjects without diabetes should also be investigated.

Impact of metformin use on survival outcomes in non-small cell lung cancer treated with platinum

Preclinical evidence suggests that metformin, a widely used antidiabetic drug, may have a sensitizing effect on platinum. The purpose of this study was to evaluate the survival outcomes for non-small cell lung cancer (NSCLC) patients with type 2 diabetes mellitus (T2DM) using metformin during platinum-based chemotherapy.The clinicopathological parameters and survival data of 75 NSCLC patients with T2DM from January 2008 to December 2011 were collected and analyzed retrospectively. Patients were divided into 2 groups: metformin exposure group (n = 27) and non-metformin group (patients using other hypoglycemic agents or no drug for controlling n = 48). Univariate and multivariate analyses were performed to assess the association of metformin usage with overall survival (OS).Mean follow-up time was 58.7 months. The mean survival time was 36.74 months in the metformin group and 40.21 months in the non-metformin group. There was no significant difference in survival time between the 2 groups (P = .661). After adjusting gender, age, smoking status, tumor stage, tumor histology, and differentiation, multivariate analysis showed that metformin was not associated with the OS in NSCLC patients treated with concurrent platinum-based chemotherapy (hazard ratio: 1.071, 95% confidence interval: 0.577-1.986, P = .828).Our results indicated that metformin exposure had no significant effect on OS in NSCLC patients treated with platinum-based chemotherapy. Further studies are warranted to evaluate whether metformin could affect the survival of NSCLC patients treated with platinum-based chemotherapy.

Pleiotropic Effects of Metformin on Cancer

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