Reduced colorectal cancer incidence in type 2 diabetic patients treated with metformin: a meta-analysis

Estrogen Receptor Is Required for Metformin-Induced Apoptosis in Breast Cancer Cells Under Hyperglycemic Conditions

Backgrounds

About 25% to 30% of estrogen receptor (ER)-positive breast cancer patients develop resistance to endocrine therapy. Human epidermal growth factor receptor 2 (HER2) has been shown to cooperate with several growth factors that regulate cellular energy metabolism, including the insulin-like growth factor 1 receptor (IGF-1R).

Objective

As the first-line therapy for type 2 diabetes mellitus (T2DM) patients, metformin is widely known to inhibit the metabolic reprogramming of cancer cells. This study aims to investigate metformin's efficacy in inhibiting endocrine resistance related to genes regulating energy metabolism in both ER-positive and ER-negative breast cancer cell lines under hyperglycemic conditions.

Design and methods

MDA-MB-361 (ER-positive, HER2-positive) and SKBR3 (ER-negative, HER2-positive) cancer cell lines were used to represent ER status. Cell viability and cell survival rate were measured using the colorimetric assay of Cell Counting Kit-8. All mRNA levels were quantified using real-time quantitative polymerase chain reaction preceded by reverse transcription. A P value of <.05 was considered statistically significant.

Results

Unlike MDA-MB-361, SKBR3 were found to acquire resistance upon metformin treatment in hyperglycemic conditions. Moreover, the mRNA expression of IGF-1R and its downstream signaling, such as the mammalian target of rapamycin (mTOR), was not affected by metformin. Meanwhile, the mRNA expression level of ribosomal S6 kinase 1 (S6K1) was upregulated, whereas forkhead box O1 (FOXO1) was downregulated after metformin treatment in hyperglycemic conditions.

Conclusions

This preliminary study suggests that an alternative pathway of metformin resistance may exist in the absence of ERα. Therefore, relying solely on metformin may be inadequate to inhibit the aggressiveness of breast cancer cells.

Metformin Does not Affect Outcomes in Patients With Locally Advanced Rectal Cancer Treated With Neoadjuvant Therapy and Resection

INTRODUCTION

There is emerging evidence that metformin may have a protective effect in patients with cancer. However, its current evidence in locally advanced rectal cancer (LARC) is inconclusive. We aim to assess the effect of metformin on long-term outcomes in patients with LARC who received neoadjuvant therapy and surgical resection.

METHODS

A retrospective review of 324 patients with nonmetastatic LARC who received neoadjuvant therapy and major surgical resection from 2004 to 2018. There were 27 patients who received metformin before surgery and 297 patients who did not receive metformin.

RESULTS

Metformin users were associated with a significantly higher age, BMI, ASA score, and 30-day readmissions (P < .05). There was no difference in overall survival (OS, P = .18) or disease-free survival (DFS, P = .33) between the two groups. On Cox regression, metformin intake did not predict OS (HR 0.85, 95% CI 0.4-1.77) when controlled for age (HR 1.04, 1.02-1.06), sex (HR 1.13, 0.69-1.85), BMI (HR 0.97, 0.92-1.02), ASA score (HR: 1.7, 1.06-2.73), TNT (HR 0.31, 0.1-0.92), pathological Stage III disease (HR 2.55, 1.51-4.32), extramural vascular invasion (EMVI) (HR 3.06, 1.7-5.5), and adjuvant therapy (HR 0.1, 0.04-0.27 for <25 months OS and HR 0.3, 0.15-0.59 for ≥25 months). Disease-free survival showed a similar trend with no significant effect of metformin (HR 0.77, 0.39-1.52) when controlled for age, sex, BMI, ASA, TNT, Stage III disease, EMVI, and adjuvant therapy.

CONCLUSION

Metformin does not affect long-term survival in LARC treated with neoadjuvant therapy followed by surgical resection. Studies with larger sample sizes are needed to validate the findings further.

Statins, commonly coprescribed drugs, and concomitant risk factors: A protective, neutral, or harmful association with common cancer types development: A 10-year multicentric retrospective lebanese study

Elevated blood levels of low-density lipoprotein cholesterol are a major cardiovascular risk factor, and cholesterol-lowering drugs are among the most prescribed drugs worldwide. Cancer is the second leading cause of death after cardiovascular diseases. The relationship between cancer development and statins intake is controversial, and there are no clear studies in Lebanon and the Middle East concerning this topic. Hence, our study aimed to search for any possible association of statin intake as well as other medications (proton pump inhibitors [PPI], metformin, Aspirin, Angiotensin-Converting Enzyme inhibitors, and fenofibrate) with lung, colorectal cancer (CRC), and bladder cancer development in the Lebanese population. A retrospective study was performed on 709 subjects divided into 2 main groups: control (no cancer ± statin intake), and cases (either lung, or colorectal, or bladder cancer ± statin intake). Collected data included the age and gender of the patient, socioeconomic status, presence of cardiovascular disease and comorbidities, cancer risk factors, and the intake type, dose, and duration of statins. Bivariate, multivariate, and binary logistic analyses were enrolled. Out of 709 participants, 63.2% were males and 75% were cancer-positive (24.1%: lung cancer, 26.7%: CRC, 24.1%: bladder cancer). The overall intake of statins was not shown to significantly affect cancer development. However, a duration-response relationship was established between Simvastatin and lung cancer (odds ratio [OR]=1.208) as well as bladder cancer (OR=1.189). No significant association was found between each statin and CRC. Although PPIs intake was associated with a possibly harmful effect on lung cancer development (OR=3.42), it revealed a protective association with CRC development (OR=0.38). Other risk factors such as smoking and age were strongly associated (harmful) with lung and bladder cancer development. Physical inactivity and a family history of CRC were each associated with a harmful effect on CRC development. A harmful association with the development of lung and bladder cancer was found with the increasing duration of intake of Simvastatin. Other drugs such as PPIs and specific risk factors were also associated negatively or positively with the development of these 3 cancers. These findings should be validated by further investigations to guide clinicians on optimal treatment options for their patients.

Metformin in the prevention of colorectal cancer with diabetes mellitus

The purpose of the review is to present an analysis of current literature data on the prospects of using the oncoprotective effect of metformin in colorectal cancer. Metformin is a drug with a long history, it is a first-line drug for the treatment of type 2 diabetes mellitus (DM2), as well as the most commonly prescribed drug worldwide. Modern researches show that in addition to its role in glucose control, metformin can reduce the risk and mortality from some malignancies and improve the response of patients with DM2 to certain types of cancer treatment. Accumulated data indicate that metformin could be a candidate drug for drug prevention of colorectal cancer.

Metformin, Statin Use, and Female Colorectal Cancer: A Population-Based Cohort Study in Taiwan

In the last few years, the incidence of colorectal cancer (CRC) in women has gradually increased. However, epidemiological studies on the relationship between type II diabetes mellitus (T2DM) and female CRC and the effect of metformin or statins on female CRC are insufficient. To determine their association, we conducted a population-based cohort study on women in Taiwan. We collected data on a total of 396,521 women aged 40 to 64 years old from 1 January 2007 to 31 December 2009 from the National Health Insurance Research Database. We followed up on all participants in the cohort until the occurrence of CRC, the date for all death, or 31 December 2015. Full development of CRC was identified using the International Classification of Disease (ICD), 9th Revision, code 153. We estimated hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) using the Cox proportional hazards model. Both metformin (adjusted hazard ratio, aHR = 1.12; 95% CI: 0.934–1.335, p = 0.227) and statin (aHR = 1.03; 95% CI: 0.906–1.172, p = 0.645) use showed no association with female CRC in a multivariate analysis. The findings indicate that metformin and statin use showed no protective effect against female colorectal cancer (CRC). An additional randomized trial is necessary to investigate the effect of metformin and statin use in CRC prevention.

Development and evaluation of core-shell nanocarrier system for enhancing the cytotoxicity of doxorubicin/ metformin combination against breast cancer cell line

Breast cancer is the most invasive and life-threatening cancer in women. The treatment options are usually a combination of mastectomy, radiation therapy, hormonal therapy and chemotherapy. As a standard practice, doxorubicin (DOX) is one of the commonly used drugs for breast cancer treatment. However, DOX is known to have many harmful adverse effects including its cardiotoxicity. Hence, recent reports used metformin (MET), an anti-diabetic drug, as an adjuvant therapy to decrease the severity of DOX's adverse effects and to improve its ultimate therapeutic outcome. The current study is aimed at co-loading and enhancing the encapsulation efficiency of the hydrophilic DOX and MET in poly(lactic-co-glycolic acid) (PLGA) nanocapsules (NCs) with oil core for breast cancer treatment. The NCs were developed by single emulsification-solvent diffusion technique, and were optimized through using two types of oils, pluronics and PLGA (50:50) of different molecular weights followed by various physicochemical characterizations. The obtained DOX/MET-loaded NCs showed the size and polydispersity index (PDI) of 203.0 ± 3.4 nm and 0.081 ± 0.03, respectively with a surface charge of -2.15 ± 0.2 mV. The entrapment efficiency of DOX and MET were about 93.7% ± 2.9 and 70% ± 1.6, respectively. The developed PLGA core-shell NCs successfully sustained the DOX/MET release for more than 30 days. The in-vitro results showed a significant enhancement in DOX cytotoxic effect as well as a duplication in its apoptotic effect upon addition of MET for both free DOX/MET combination and DOX/MET-loaded PLGA NCs against MCF-7. Besides, flow cytometry demonstrated that the DOX/MET-loaded NCs possess their antitumor effect by preventing DNA replication and cell division. This study provides a promising facile, rapid and reproducible single emulsification-solvent diffusion technique for improving the encapsulation and release of hydrophilic drugs in nanocapsules for biomedical applications.

Diabetes and Risks of Right-Sided and Left-Sided Colon Cancer: A Meta-Analysis of Prospective Cohorts

Background and Aims

Diabetes is associated with an increased risk of colon cancer (CC). Epidemiologic studies previously reported a higher risk for right-sided colon cancer (RCC) compare to left-sided colon cancer (LCC), although data are conflicting. We performed a meta-analysis to investigate this issue.

Methods

We systematically searched the PubMed, EMBASE, Web of Science and Cochrane Library database for prospective cohort studies published up to June 2021. Studies were included if they reported site-specific estimates of the relative risk (RR) between diabetes and the risks of RCC and LCC. Random effects meta-analyses with inverse variance weighting were used to estimate the pooled site-specific RRs and the RCC-to-LCC ratio of RRs (RRRs).

Results

Data from 10 prospective cohort studies, representing 1,642,823 individuals (mainly white) and 17,624 CC patients, were included in the analysis. Diabetes was associated with an increased risk of both RCC (RR =1.35, 95% CI = 1.24-1.47) and LCC (RR = 1.18, 95% CI = 1.08-1.28). After adjusting for major risk factors, individuals with diabetes had a greater risk for RCC than for LCC (RRR = 1.13, 95% CI = 1.02-1.26), with no significant heterogeneity between studies (I² = 0%).

Conclusions

This meta-analysis indicates that diabetes is associated with a higher risk for RCC than for LCC. Our findings suggest that colonoscopic surveillance in diabetic patients with careful examination of the right colon is warranted.

Diabetes mellitus promoted lymph node metastasis in gastric cancer: a 15-year single-institution experience

Background:

Previous studies have revealed that diabetes mellitus (DM) promotes disease progress of gastric cancer (GC). This study aimed to further investigating whether DM advanced lymph nodes (LNs) metastasis in GC.

Methods:

The clinicopathologic data of GC patients with >15 examined LN (ELN) between October 2004 and December 2019 from a prospectively maintained database were included. The observational outcomes included the number (N3b status) and anatomical distribution (N3 stations) of metastatic LN (MLN).

Results:

A total of 2142 eligible patients were included in the study between October 2004 and December 2019. N3 stations metastasis (26.8% in DM vs. 19.3% in non-DM, P = 0.026) and N3b status (18.8% in DM vs. 12.8% in non-DM, P = 0.039) were more advanced in the DM group, and multivariate logistic regression analyses confirmed that DM was an independent factor of developing N3 stations metastasis (odds ratio [OR] = 1.771, P = 0.011) and N3b status (OR = 1.752, P = 0.028). Also, multivariate analyses determined DM was independently associated with more MLN (β = 1.424, P = 0.047). The preponderance of N3 stations metastasis (DM vs. non-DM, T1–2: 2.2% vs. 4.9%, T3: 29.0% vs. 20.3%, T4a: 38.9% vs. 25.8%, T4b: 50.0% vs. 36.6%; ELN16–29: 8.6% vs. 10.4%, ELN30–44: 27.9% vs. 20.5%, ELN ≥ 45: 37.7% vs. 25.3%), N3b status (DM vs. non-DM, T1–2: 0% vs. 1.7%, T3: 16.1% vs. 5.1%, T4a: 27.8% vs. 19.1%, T4b: 44.0% vs. 28.0%; ELN16–29: 8.6% vs. 7.9%, ELN30–44: 18.0% vs. 11.8%, ELN ≥ 45: 26.4% vs. 17.3%), and the number of MLN (DM vs. non-DM, T1–2: 0.4 vs. 1.1, T3: 8.6 vs. 5.2, T4a: 9.7 vs. 8.6, T4b: 17.0 vs. 12.8; ELN16–29: 3.6 vs. 4.6, ELN30–44: 5.8 vs. 5.5, ELN ≥ 45: 12.0 vs. 7.7) of DM group increased with the advancement of primary tumor depth stage and raising of ELN.

Conclusions:

DM was an independent risk factor for promoting LN metastasis. The preponderance of LN involvement in the DM group was aggravated with the advancement of tumor depth.

Medication use and risk of proximal colon cancer: a systematic review of prospective studies with narrative synthesis and meta-analysis

PURPOSE

Evidence of differences in the etiology of, and poorer survival from, proximal colon compared to the distal colorectum, necessitates research into its risk factors. This systematic review summarizes the evidence on medication use and proximal colon cancer risk.

METHODS

MEDLINE and EMBASE were searched for prospective studies investigating nine medication groups, namely non-steroidal anti-inflammatory drugs (NSAIDs), exogenous hormones, i.e., hormone replacement therapy (HRT) or oral contraceptives (OCs), statins, proton pump inhibitors, anti-hypertensives, metformin (an antidiabetic), antidiarrheals or laxatives, and the risk of proximal colon cancer. Narrative synthesis and meta-analyses, using random effects models to estimate risk ratios (RRs) and 95% confidence intervals (CIs), were conducted.

RESULTS

Twenty nine publications investigating NSAIDs (n = 13), exogenous hormones [HRT (n = 9) or OCs (n = 4)] statins (n = 5), anti-hypertensives (n = 1), and metformin (n = 1) were included. Summary RRs reported a protective effect of aspirin use (RR 0.80, 95% CI 0.73-0.89) but no associations between HRT (RR 0.92, 95% CI 0.83-1.02), OC (RR 1.06, 95% CI 0.98-1.14) or statin use (RR 0.94, 95% CI 0.67-1.31), and proximal colon cancer incidence compared to never/non-use. One study on metformin and one on anti-hypertensives reported no association. Sources of between-study heterogeneity included study design, period of exposure ascertainment, exposure source, and exposure comparison, but this exploration was hindered by the small numbers of studies.

CONCLUSION

Despite some studies on NSAID or HRT use, evidence on the impact of a range of medications on proximal colon cancer risk is limited. This highlights the need for more research to inform chemoprevention strategies.

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.

Role of gut microbiome in regulating the effectiveness of metformin in reducing colorectal cancer in type 2 diabetes

The prevalence of colorectal cancer (CRC) and type 2 diabetes mellitus (T2DM) is increasing globally. It is rarely noticed that the incidence of CRC is higher in patients with T2DM. What needs to be mentioned is that metformin, a commonly used clinical drug for T2DM, attracts scholars’ attention because of its benefits in lowering the risk of developing CRC. Hence, we try to find the common grounds of initiation of T2DM and CRC and the reason why metformin reduces the risk of CRC in patients with T2DM. We noticed consistent changes of gut microbiota, such as elevated Bacteroides, Prevotella and Bifidobacterium and depressed Firmicutes and Lactobacillus. Furthermore, many studies in recent years have proved that the efficacy of metformin, such as improving blood glucose, depends on the gut microbiota. Coincidentally, the progression of CRC is inseparable from the contributions of gut microbiota. Therefore, we first proposed the concept of the metformin-gut microbiota–CRC (in T2DM) axis to explain the effect of metformin in reducing CRC in patients with T2DM. In this review, we elaborated the new concept and its potential clinical application value.

Association of Metformin, Other Antidiabetic Medications, and Statins With Incidence of Colon Cancer in Patients With Type 2 Diabetes

BACKGROUND

Metformin and statins may have anticancer effects, with plausible cellular mechanisms. However, the association of these agents with the risk of colorectal cancer is unclear.

PATIENTS AND METHODS

This was a retrospective cohort study on a large population (N = 316,317) of patients with type 2 diabetes. Data were obtained from the Diabetes in Finland database (FinDM). In a full cohort analysis, hazard ratios (HRs) with their 95% confidence intervals (CIs) for ever use versus never use were estimated using a multiple Poisson regression model. A nested case-control design within the cohort was used to examine the association of colon cancer (CC) with the defined daily dose of medication. The data were analyzed by conditional logistic regression. The analyses were adjusted for the patient's age, sex, and duration of diabetes.

RESULTS

In total, 1351 CC cases were diagnosed during 1996-2011. The results revealed insufficient evidence for an association between metformin (HR, 1.01; 95% CI, 0.90-1.14), other oral antidiabetic medications (HR, 1.05; 95% CI, 0.93-1.19), insulin (HR, 1.02; 95% CI, 0.86-1.22), or statins (HR, 0.94; 95% CI, 0.84-1.05) and the incidence of CC in the full cohort analysis. The results from the case-control study were similar, with no consistent trend in the incidence of CC according to the cumulative dose of metformin or the other studied medications.

CONCLUSION

This study found insufficient evidence for an association between metformin, insulin, other oral type 2 diabetes medications, or statins and the incidence of CC.

The effect of metformin on esophageal cancer risk in patients with type 2 diabetes mellitus: a systematic review and meta‑analysis

OBJECTIVE

Recently, numerous studies have yielded inconsistent results regarding the effect of metformin on esophageal cancer risk in type 2 diabetes mellitus patients. The purpose of this study is to systematically assess this effect using meta-analysis.

METHODS

We searched clinical studies on metformin and esophageal cancer risk in PubMed, Embase, and the Cochrane Library. After literature screening, a series of meta-analyses were conducted using RevMan 5.3 software. The pooled hazard ratio (HR) and the corresponding 95% confidence interval (CI) were used as the effect size.

RESULTS

Five eligible studies (four cohort studies and one case-control study) were included for our meta-analysis using a random-effect model. The analysis showed that metformin could not reduce esophageal cancer risk in type 2 diabetes mellitus patients (HR 0.88, 95% CI 0.60-1.28, P > 0.05). Subgroup analyses by geographic location showed that metformin significantly reduced esophageal cancer risk in Asian patients with type 2 diabetes mellitus (HR 0.59, 95% CI 0.39-0.91, P = 0.02), without heterogeneity between studies (P = 0.80 and I² = 0%).

CONCLUSIONS

Overall, our systematic review and meta-analysis demonstrate that metformin does not reduce esophageal cancer risk in type 2 diabetes mellitus patients. However, a significant reduction in esophageal cancer risk in Asian populations remains to be clarified.

Impact of diabetes on prognosis of gastric cancer patients performed with gastrectomy

Objective

This study aimed to determine the impact of type 2 diabetes mellitus (T2DM) on clinical outcomes of gastric cancer (GC) patients and explore whether metformin use and good glycemic control could reverse it.

Methods

Clinicopathologic data of consecutive GC patients who underwent gastrectomy at Nanfang Hospital between October 2004 and December 2015 were included. Propensity score matching (PSM) was performed to balance the important factors of the disease status between non-T2DM and T2DM group. The last follow-up time was January 2019.

Results

A total of 1,692 eligible patients (1,621 non-T2DM vs. 71 T2DM) were included. After PSM, non-T2DM group (n=139) and T2DM group (n=71) were more balanced in baseline variables. The 5-year cancer-specific survival (CSS) rate in T2DM group (47.0%) was inferior to that in non-T2DM group (58.0%), but did not reach statistical significance [hazard ratio (HR)=1.319, 95% confidence interval (95% CI): 0.868−2.005, P=0.192]. While the 5-year progress-free survival (PFS) rate of T2DM group (40.6%) is significantly worse than that in non-T2DM group (56.3%) (HR=1.516, 95% CI: 1.004−2.290, P=0.045). Univariate and multivariate analyses showed that T2DM was an independent risk factor for PFS but not for CSS. In T2DM group, metformin use subgroup was associated with superior 5-year CSS and PFS in compared with non-metformin use subgroup, although the difference was not statistically significant (5-year CSS: 48.0%vs. 45.4%, HR=0.680, 95% CI: 0.352−1.313, P=0.246; 5-year PFS: 43.5%vs. 35.7%, HR=0.763, 95% CI: 0.400−1.454, P=0.406). The 5-year CSS rate was 47.5% in good glycemic control subgroup and 44.1% in poor glycemic control subgroup (HR=0.826, 95% CI: 0.398−1.713, P=0.605). And both two subgroups yielded a similar 5-year PFS rate (42.2%vs. 36.3%, HR=0.908, 95% CI: 0.441−1.871, P=0.792).

Conclusions

DM promoted disease progress of GC after gastrectomy but had not yet led to the significant discrepancy of CSS. For GC patients with T2DM, metformin use was associated with superior survival but without statistical significance, while better glycemic control could not improve the prognosis.

Metformin in colorectal cancer: molecular mechanism, preclinical and clinical aspects

Growing evidence showed the increased prevalence of cancer incidents, particularly colorectal cancer, among type 2 diabetic mellitus patients. Antidiabetic medications such as, insulin, sulfonylureas, dipeptyl peptidase (DPP) 4 inhibitors and glucose-dependent insulinotropic peptide (GLP-1) analogues increased the additional risk of different cancers to diabetic patients. Conversely, metformin has drawn attention among physicians and researchers since its use as antidiabetic drug exhibited beneficial effect in the prevention and treatment of cancer in diabetic patients as well as an independent anticancer drug. This review aims to provide the comprehensive information on the use of metformin at preclinical and clinical stages among colorectal cancer patients. We highlight the efficacy of metformin as an anti-proliferative, chemopreventive, apoptosis inducing agent, adjuvant, and radio-chemosensitizer in various colorectal cancer models. This multifarious effects of metformin is largely attributed to its capability in modulating upstream and downstream molecular targets involved in apoptosis, autophagy, cell cycle, oxidative stress, inflammation, metabolic homeostasis, and epigenetic regulation. Moreover, the review highlights metformin intake and colorectal cancer risk based on different clinical and epidemiologic results from different gender and specific population background among diabetic and non-diabetic patients. The improved understanding of metformin as a potential chemotherapeutic drug or as neo-adjuvant will provide better information for it to be used globally as an affordable, well-tolerated, and effective anticancer agent for colorectal cancer.

SGLT2 inhibition slows tumor growth in mice by reversing hyperinsulinemia

Background

Obesity confers an increased risk and accelerates the progression of multiple tumor types in rodents and humans, including both breast and colon cancer. Because sustained weight loss is rarely achieved, therapeutic approaches to slow or prevent obesity-associated cancer development have been limited, and mechanistic insights as to the obesity-cancer connection have been lacking.

Methods

E0771 breast tumors and MC38 colon tumors were treated in vivo in mice and in vitro with two mechanistically different insulin-lowering agents, a controlled-release mitochondrial protonophore (CRMP) and sodium-glucose cotransporter-2 (SGLT2) inhibitors, and tumor growth and glucose metabolism were assessed. Groups were compared by ANOVA with Bonferroni’s multiple comparisons test.

Results

Dapagliflozin slows tumor growth in two mouse models (E0771 breast cancer and MC38 colon adenocarcinoma) of obesity-associated cancers in vivo, and a mechanistically different insulin-lowering agent, CRMP, also slowed breast tumor growth through its effect to reverse hyperinsulinemia. In both models and with both agents, tumor glucose uptake and oxidation were not constitutively high, but were hormone-responsive. Restoration of hyperinsulinemia by subcutaneous insulin infusion abrogated the effects of both dapagliflozin and CRMP to slow tumor growth.

Conclusions

Taken together, these data demonstrate that hyperinsulinemia per se promotes both breast and colon cancer progression in obese mice, and highlight SGLT2 inhibitors as a clinically available means of slowing obesity-associated tumor growth due to their glucose- and insulin-lowering effects.

Uncoupling Hepatic Oxidative Phosphorylation Reduces Tumor Growth in Two Murine Models of Colon Cancer

Obesity is associated with colon cancer pathogenesis, but the underlying mechanism is actively debated. Here, we confirm that diet-induced obesity promotes tumor growth in two murine colon cancer models and show that this effect is reversed by an orally administered controlled-release mitochondrial protonophore (CRMP) that acts as a liver-specific uncoupler of oxidative phosphorylation. This agent lowered circulating insulin, and the reduction of tumor growth was abrogated by an insulin infusion raising plasma insulin to the level of high-fat-fed mice. We also demonstrate that hyperinsulinemia increases glucose uptake and oxidation in vivo in tumors and that CRMP reverses these effects. This study provides evidence that perturbations of whole-organism energy balance or hepatic energy metabolism can influence neoplastic growth. Furthermore, the data show that glucose uptake and utilization by cancers in vivo are not necessarily constitutively high but rather may vary according to the hormonal milieu.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Metformin Is Associated With Reduced Odds for Colorectal Cancer Among Persons With Diabetes

INTRODUCTION

Metformin may be associated with reduced colorectal cancer (CRC) risk, but findings from previous studies have been inconsistent and had insufficient sample sizes to examine whether the association differs by anatomic site. This study examined whether metformin was associated with reduced CRC risk, both overall and stratified by anatomic site, in a large sample of persons with diabetes who underwent colonoscopy.

METHODS

We performed a case-control study of US Veterans with prevalent diabetes who underwent colonoscopy between 1999 and 2014 using Department of Veterans Affairs electronic health record data. Cases were defined by presence of CRC at colonoscopy, while controls had normal colonoscopy. The primary exposure was metformin use at time of colonoscopy (yes/no). Association of metformin exposure with CRC (further stratified by proximal, distal, or rectal subsite) was examined using multivariable and multinomial logistic regression and summarized by odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

We included 6,650 CRC patients and 454,507 normal colonoscopy patients. CRC cases were older and had lower metformin exposure. Metformin was associated with 8% relative reduction in CRC odds (OR: 0.92, 95% CI: 0.87-0.96). By subsite, metformin was associated with a 14% statistically significant reduced rectal cancer odds (OR: 0.86, 95% CI: 0.78-0.94) but no reduced distal or proximal cancer odds.

DISCUSSION

Metformin was associated with reduced CRC odds-particularly rectal cancer-in a large sample of persons with diabetes undergoing colonoscopy.

Recent evidence on modifiable and non-modifiable risk factors for colorectal cancer (CRC): a systematic synopsis of meta-analyses from 2015 to 2017

Colorectal cancer (CRC) is a common cancer with a huge impact on international public health. This review discusses recent evidence on modifiable and non-modifiable risk factors for CRC using a systematic review method. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines on systematic reviews and meta-analyses of observational studies. The literature search was performed on the Ovid MEDLINE database and included publications from 2015 to 2017, followed by a quality assessment and a narrative synthesis. Of the 90 identified articles, there were 13 meta-analyses with statistically significant results. Seven articles discussed modifiable risk factors and six articles discussed non-modifiable risk. The modifiable risk factors with the highest risk were radiotherapy of prostate cancer (pooled odds ratio 1.68; 95% confidence interval [CI] 1.33–2.12). The non-modifiable risk factors with the highest risk was Lynch syndrome (hazard ratio 135.49; 95% CI 111.55–164.57). This review discovered new and previously known risk factors for CRC. Recent evidence shows that research on CRC risk factors is continuing to grow indicating that more studies on risk factors are needed to optimize CRC prevention and early detection.

Metformin and 4SC-202 synergistically promote intrinsic cell apoptosis by accelerating ΔNp63 ubiquitination and degradation in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common and aggressive epithelial tumor in the head and neck region with a rising incidence. Despite the advances in basic science and clinical research, the overall survival rate of OSCC remains low. Thus finding novel effective therapeutic agents for OSCC is necessary. In this study, we investigated the effects and mechanisms of combined metformin and 4SC-202 in OSCC. Our results showed that metformin and 4SC-202 synergistically suppressed the proliferation and promoted the intrinsic apoptosis of OSCC cells in vitro and in vivo. Importantly, the proteasome inhibitor MG132 impeded the ΔNp63-decreasing effects after metformin and 4SC-202 treatment, indicating that metformin and 4SC-202 could promote the degradation of ΔNp63 protein. Moreover, ubiquitination level of ΔNp63 increased after metformin or/and 4SC-202 administration. Furthermore, we revealed that ΔNp63 mediated anticancer effects of metformin and 4SC-202, as overexpression or suppression of ΔNp63 could attenuate or facilitate the apoptosis rate of OSCC under metformin or/and 4SC-202 treatment. Collectively, metformin and 4SC-202 synergistically promote intrinsic apoptosis through accelerating ubiquitin-mediated degradation of ΔNp63 in OSCC, and this co-treatment can serve as a potential therapeutic scheme for OSCC.

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.

Phenformin and metformin inhibit growth and migration of LN229 glioma cells in vitro and in vivo

Background

Malignant glioma is refractory to conventional treatment, highlighting a need to develop novel efficacious therapies. Biguanides, a class of oral antidiabetic drug, have been thought to inhibit proliferation and metastasis in a variety of cancers.

Purpose

The objective of this study was to investigate the affections of biguanides, phenformin (Phen) and metformin (Met), on growth and migration of glioma cells LN229 in vitro and in vivo.

Methods

Glioma cells LN229 were treated with Phen or Met, then cell proliferation and death were evaluated by MTT assay and PI stain, and cell cycle were evaluated using flow cytometric analysis, meantime wound healing assay and transwell migration assay were performed to detect cell migration ability. In addition, LN229 were injected in thigh of nude mice, and the mice were treated with Phen or Met to detect the effect of Phen and Met in vivo.

Results

Phen and Met could significantly inhibit cell growth through inhibiting cell proliferation, promoting cell death and disturbing cell cycle, and these drugs also could inhibit cell colony formation in glioma cells LN229 in vitro. Meanwhile, both Phen and Met could significantly inhibit cell migration of LN229 in vitro, through effecting the expression of E-cadherin and Vimentin. In addition, both Phen and Met inhibited the growth and migration of LN229 in a tumor xenograft model. Furthermore, Phen and Met were associated with the increased level of ROS of cell mitochondrial, and ROS inhibitor NAC could significantly rescue the cell death induced by Phen and Met.

Conclusion

Phen and Met displayed powerful antitumor effects of LN229, and our findings powerfully suggest the possibility of Phen and Met being used as an adjuvant agent in the treatment of glioma patients.

Antitumor effects of metformin are a result of inhibiting nuclear factor kappa B nuclear translocation in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is an intractable digestive organ cancer that has proven difficult to treat despite multidisciplinary therapy, and a new treatment strategy is demanded. Metformin is used for type 2 diabetes mellitus and its antitumor effects have been reported recently. Metformin exerts antitumor effects in various respects, such as inhibiting inflammation, tumor growth and epithelial‐mesenchymal transition (EMT). However, few reports have described the efficacy of metformin on ESCC, and their findings have been controversial. We analyzed the antitumor effects of metformin and clarified its effects on anti‐inflammation, growth suppression and EMT inhibition. Activation of nuclear factor kappa B (NF‐κB), the major transcription factor induced by inflammation, was investigated by immunostaining. We found that localization of NF‐κB in the nucleus was reduced after metformin treatment. This suggests that metformin inhibited the activation of NF‐κB. Metformin inhibited tumor growth and induced apoptosis in ESCC cell lines. Associated with EMT, we examined cell motility by a wound healing assay and the epithelial marker E‐cadherin expression of various ESCC cell lines by western blotting. Metformin inhibited cell motility and induced E‐cadherin expression. In conclusion, metformin showed multiple antitumor effects such as growth suppression, invasion inhibition, and control of EMT by inhibiting NF‐κB localization on ESCC. Further exploration of the marker of treatment efficacy and combination therapy could result in the possibility for novel treatment to use metformin on ESCC.

Metformin and aspirin treatment could lead to an improved survival rate for Type 2 diabetic patients with stage II and III colorectal adenocarcinoma relative to non-diabetic patients

Metformin, the drug of choice in the treatment of type 2 diabetes mellitus (DM2), in addition to aspirin (ASA), the drug prescribed for cardioprotection of diabetic and non-diabetic patients, have an inhibitory effect on cancer cell survival. The present population-based study conducted in the province of Trieste (Italy), aimed to investigate the prevalence of DM2 in patients with colorectal adenocarcinoma (CRC) and survival for CRC in diabetic and nondiabetic patients. All permanent residents diagnosed with a CRC between 2004 and 2007 were ascertained through the regional health information system. CRC-specific and relative survival probabilities were computed for each group of patients defined by CRC stage, presence or absence of DM2 treated with metformin, and presence or absence of daily ASA therapy. A total of 515 CRC patients without DM2 and 156 with DM2 treated with metformin were enrolled in the study. At the time of CRC diagnosis, 71 (14%) nondiabetic and 39 (25%) diabetic patients were taking ASA daily. The five-year relative survival for stage III CRC was 101% [95% confidence interval (CI)=76-126] in the 18 patients with DM2 treated with metformin and ASA, 55% (95% CI=31-78) in the 23 without DM2 treated with ASA, 55% (95% CI=45-65) in the 150 without DM2 not taking ASA, and 29% (95% CI=13-45) in the 43 with DM2 treated with metformin, however not with ASA. The findings support the hypothesis of a possible inhibitory effect of metformin and ASA on CRC cells. Randomized controlled trials are required to verify this hypothesis.

Metabolic Profiles Associated With Metformin Efficacy in Cancer

Metformin is one of the most commonly prescribed medications for the treatment of type 2 diabetes. Numerous reports have suggested potential anti-cancerous and cancer preventive properties of metformin, although these findings vary depending on the intrinsic properties of the tumor, as well as the systemic physiology of patients. These intriguing studies have led to a renewed interest in metformin use in the oncology setting, and fueled research to unveil its elusive mode of action. It is now appreciated that metformin inhibits complex I of the electron transport chain in mitochondria, causing bioenergetic stress in cancer cells, and rendering them dependent on glycolysis for ATP production. Understanding the mode of action of metformin and the consequences of its use on cancer cell bioenergetics permits the identification of cancer types most susceptible to metformin action. Such knowledge may also shed light on the varying results to metformin usage that have been observed in clinical trials. In this review, we discuss metabolic profiles of cancer cells that are associated with metformin sensitivity, and rationalize combinatorial treatment options. We use the concept of bioenergetic flexibility, which has recently emerged in the field of cancer cell metabolism, to further understand metabolic rearrangements that occur upon metformin treatment. Finally, we advance the notion that metabolic fitness of cancer cells increases during progression to metastatic disease and the emergence of therapeutic resistance. As a result, sophisticated combinatorial approaches that prevent metabolic compensatory mechanisms will be required to effectively manage metastatic disease.

Translational Geroscience: From invertebrate models to companion animal and human interventions

Translational geroscience is an interdisciplinary field descended from basic gerontology that seeks to identify, validate, and clinically apply interventions to maximize healthy, disease-free lifespan. In this review, we describe a research pipeline for the identification and validation of lifespan extending interventions. Beginning in invertebrate model systems, interventions are discovered and then characterized using other invertebrate model systems (evolutionary translation), models of genetic diversity, and disease models. Vertebrate model systems, particularly mice, can then be utilized to validate interventions in mammalian systems. Collaborative, multi-site efforts, like the Interventions Testing Program (ITP), provide a key resource to assess intervention robustness in genetically diverse mice. Mouse disease models provide a tool to understand the broader utility of longevity interventions. Beyond mouse models, we advocate for studies in companion pets. The Dog Aging Project is an exciting example of translating research in dogs, both to develop a model system and to extend their healthy lifespan as a goal in itself. Finally, we discuss proposed and ongoing intervention studies in humans, unmet needs for validating interventions in humans, and speculate on how differences in survival among human populations may influence intervention efficacy.

Therapeutic strategies against cancer stem cells in human colorectal cancer

Colorectal cancer (CRC) is the third most frequent malignancy and represents the fourth most common cause of cancer-associated mortalities in the world. Despite many advances in the treatment of CRC, the 5-year survival rate of patients with CRC remains unsatisfactory due to tumor recurrence and metastases. Recently, cancer stem cells (CSCs), have been suggested to be responsible for the initiation and relapse of the disease, and have been identified in CRC. Due to their basic biological features, which include self-renewal and pluripotency, CSCs may be novel therapeutic targets for CRC and other cancer types. Conventional therapeutics only act on proliferating and mature cancer cells, while quiescent CSCs survive and often become resistant to chemotherapy. In this review, markers of CRC-CSCs are evaluated and the recently introduced experimental therapies that specifically target these cells by inducing CSC proliferation, differentiation and sensitization to apoptotic signals via molecules including Dickkopf-1, bone morphogenetic protein 4, Kindlin-1, tankyrases, and p21-activated kinase 1, are discussed. In addition, novel strategies aimed at inhibiting some crucial processes engaged in cancer progression regulated by the Wnt, transforming growth factor β and Notch signaling pathways (pyrvinium pamoate, silibinin, PRI-724, P17, and P144 peptides) are also evaluated. Although the metabolic alterations in cancer were first described decades ago, it is only recently that the concept of targeting key regulatory molecules of cell metabolism, such as sirtuin 1 (miR-34a) and AMPK (metformin), has emerged. In conclusion, the discovery of CSCs has resulted in the definition of novel therapeutic targets and the development of novel experimental therapies for CRC. However, further investigations are required in order to apply these novel drugs in human CRC.

Metformin Suppressed CXCL8 Expression and Cell Migration in HEK293/TLR4 Cell Line

Chronic inflammation is associated with cancer. CXCL8 promotes tumor microenvironment construction through recruiting leukocytes and endothelial progenitor cells that are involved in angiogenesis. It also enhances tumor cell proliferation and migration. Metformin, type II diabetes medication, demonstrates anticancer properties via suppressing inflammation, tumor cell proliferation, angiogenesis, and metastasis. This study intended to address the role of metformin in regulation of CXCL8 expression and cell proliferation and migration. Our data indicated that metformin suppressed LPS-induced CXCL8 expression in a dose-dependent manner through inhibiting NF-κB, but not AP-1 and C/EBP, activities under the conditions we used. This inhibitory effect of metformin is achieved through dampening LPS-induced NF-κB nuclear translocation. Cell migration was inhibited by metformin under high dose (10 mM), but not cell proliferation.

Repurposing metformin for the prevention of cancer and cancer recurrence

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

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

OBJECTIVE

Recent studies have reported conflicting results on the correlation between metformin use and outcomes in patients with colorectal cancer (CRC). A meta-analysis was performed to evaluate the efficacy of metformin therapy on the prognosis of CRC patients with type 2 diabetes mellitus (T2DM).

METHODS

We conducted a systematic search of PubMed, EMBASE, the Cochrane Library, and the Web of Science for related articles up to August 2016. Two investigators independently identified and extracted information. Pooled risk estimates [hazard ratios (HRs)] and 95% confidence intervals (CIs) were calculated using fixed-effects models. The risk of publication bias was assessed by examining funnel plot asymmetry as well as Egger's test and Begg's test.

RESULTS

Of 81 articles identified, 8 retrospective cohort studies, representing 6098 cases of CRC patients with T2DM who used metformin and 4954 cases of CRC patients with T2DM who did not use metformin, were included in this meta-analysis. There was no significant heterogeneity and quality difference between studies. Metformin users had significantly improved overall survival (OS) (HR = 0.82, 95% CI: 0.77-0.87, P = 0.000). However, Metformin use cannot affect CRC-specific survival (HR = 0.84, 95% CI: 0.69-1.02, P = 0.079) compared to non-users.

CONCLUSION

This meta-analysis suggests that metformin use may improve survival among CRC patients with T2DM. However, prospective controlled studies are still needed to rigorously evaluate the efficacy of metformin as an anti-tumor agent.

Diabetes-induced mechanophysiological changes in the small intestine and colon

The disorders of gastrointestinal (GI) tract including intestine and colon are common in the patients with diabetes mellitus (DM). DM induced intestinal and colonic structural and biomechanical remodeling in animals and humans. The remodeling is closely related to motor-sensory abnormalities of the intestine and colon which are associated with the symptoms frequently encountered in patients with DM such as diarrhea and constipation. In this review, firstly we review DM-induced histomorphological and biomechanical remodeling of intestine and colon. Secondly we review motor-sensory dysfunction and how they relate to intestinal and colonic abnormalities. Finally the clinical consequences of DM-induced changes in the intestine and colon including diarrhea, constipation, gut microbiota change and colon cancer are discussed. The final goal is to increase the understanding of DM-induced changes in the gut and the subsequent clinical consequences in order to provide the clinicians with a better understanding of the GI disorders in diabetic patients and facilitates treatments tailored to these patients.

Metformin Improves Overall Survival of Colorectal Cancer Patients with Diabetes: A Meta-Analysis

Introduction. Diabetic population has a higher risk of colorectal cancer (CRC) incidence and mortality than nondiabetics. The role of metformin in CRC prognosis is still controversial. The meta-analysis aims to investigate whether metformin improves the survival of diabetic CRC patients. Methods. PubMed, EMBASE, and Cochrane Library were searched till July 1, 2016. Cohort studies were included. All articles were evaluated by Newcastle-Ottawa Scale. Hazard Ratios (HRs) with 95% confidence intervals (CIs) for each study were calculated and pooled HRs with corresponding 95% CIs were generated using the random-effects model. Heterogeneity and publication bias were assessed. Results. We included seven cohort studies with a medium heterogeneity (I² = 56.1% and p = 0.033) in our meta-analysis. An improved overall survival (OS) for metformin users over nonusers among colorectal cancers with diabetes was noted (HR 0.75; 95% CI 0.65 to 0.87). However, metformin reveals no benefits for cancer-specific survival (HR 0.79, 95%, CI 0.58 to 1.08). Conclusions. Metformin prolongs the OS of diabetic CRC patients, but it does not affect the CRC-specific survival. Metformin may be a good choice in treating CRC patients with diabetes mellitus in clinical settings.