Understanding the benefit of metformin use in cancer treatment

Interfering with Tumor Hypoxia for Radiotherapy Optimization

Hypoxia in solid tumors is an important predictor of treatment resistance and poor clinical outcome. The significance of hypoxia in the development of resistance to radiotherapy has been recognized for decades and the search for hypoxia-targeting, radiosensitizing agents continues. This review summarizes the main hypoxia-related processes relevant for radiotherapy on the subcellular, cellular and tissue level and discusses the significance of hypoxia in radiation oncology, especially with regard to the current shift towards hypofractionated treatment regimens. Furthermore, we discuss the strategies to interfere with hypoxia for radiotherapy optimization, and we highlight novel insights into the molecular pathways involved in hypoxia that might be utilized to increase the efficacy of radiotherapy.

The impact of chemical engineering and technological advances on managing diabetes: present and future concepts

Monitoring blood glucose levels for diabetic patients is critical to achieve tight glycaemic control. As none of the current antidiabetic treatments restore lost functional β-cell mass in diabetic patients, insulin injections and the use of insulin pumps are most widely used in the management of glycaemia. The use of advanced and intelligent chemical engineering, together with the incorporation of micro- and nanotechnological-based processes have lately revolutionized diabetic management. The start of this concept goes back to 1974 with the description of an electrode that repeatedly measures the level of blood glucose and triggers insulin release from an infusion pump to enter the blood stream from a small reservoir upon need. Next to the insulin pumps, other drug delivery routes, including nasal, transdermal and buccal, are currently investigated. These processes necessitate competences from chemists, engineers-alike and innovative views of pharmacologists and diabetologists. Engineered micro and nanostructures hold a unique potential when it comes to drug delivery applications required for the treatment of diabetic patients. As the technical aspects of chemistry, biology and informatics on medicine are expanding fast, time has come to step back and to evaluate the impact of technology-driven chemistry on diabetics and how the bridges from research laboratories to market products are established. In this review, the large variety of therapeutic approaches proposed in the last five years for diabetic patients are discussed in an applied context. A survey of the state of the art of closed-loop insulin delivery strategies in response to blood glucose level fluctuation is provided together with insights into the emerging key technologies for diagnosis and drug development. Chemical engineering strategies centered on preserving and regenerating functional pancreatic β-cell mass are evoked in addition as they represent a permanent solution for diabetic patients.

Biguanides: Species with versatile therapeutic applications

Biguanides are compounds in which two guanidine moieties are fused to form a highly conjugated system. Biguanides are highly basic and hence they are available as salts mostly hydrochloride salts, these cationic species have been found to exhibit many therapeutic properties. This review covers the research and development carried out on biguanides and accounts the various therapeutic applications of drugs containing biguanide group-such as antimalarial, antidiabetic, antiviral, anticancer, antibacterial, antifungal, anti-tubercular, antifilarial, anti-HIV, as well as other biological activities. The aim of this review is to compile all the medicinal chemistry applications of this class of compounds so as to pave way for the accelerated efforts in finding the drug action mechanisms associated with this class of compounds. Importance has been given to the organic chemistry of these biguanide derivatives also.

Metformin Increases Survival in Hypopharyngeal Cancer Patients with Diabetes Mellitus: Retrospective Cohort Study and Cell-Based Analysis

Hypopharyngeal squamous cell carcinoma (HSCC) is usually diagnosed at an advanced stage, leading to a poor prognosis. Even after improvement of surgical techniques, chemotherapy, and radiation technology, the survival rate of HSCC remains poor. Metformin, which is commonly used for type 2 diabetes mellitus (DM), has been suggested to reduce the risk of various cancer types. However, only a few clinical studies mentioned the relationship between metformin use and HSCC. Hence, the aim of this study was to elucidate the specific effect and mechanism of action of metformin in hypopharyngeal cancer. We first assessed whether metformin use has an effect on hypopharyngeal cancer patients with DM by conducting a retrospective cohort study. Our results showed that DM hypopharyngeal cancer patients who used metformin exhibited significantly better overall survival rates than that without metformin treatment. The cell-based analysis further indicated that metformin treatment regulated p38/JNK pathway to reduce Cyclin D1 and Bcl-2 expressions. In addition, metformin activated the pathways of AMPKα and MEK/ERK to phosphorylate p27(Thr198) and reduce mTOR phosphorylation in cells. These actions direct cells toward G1 cell cycle arrest, apoptosis, and autophagy. Our results, through combining a clinical cohort analysis with an in vitro study, demonstrate that metformin can be used for drug repositioning in the treatment of DM patients with hypopharyngeal cancer.

Metabolism of Innate Immune Cells in Cancer

Simple Summary

Both cancer cells and immune cells depend on specific metabolic programs for their survival and function. Depending on which metabolic changes occur, immune cells can either promote or suppress the antitumor immune response. This review summarizes the metabolic pathways that polarize innate immune cells for immune activation or suppression and describes the current clinical applications of these findings.

Abstract

Cancer cells possess specific metabolic requirements for their survival, proliferation, and progression. Within a shared microenvironment, immune cells depend on competing metabolic pathways for their development and effector function. As a result, local acidification, hypoxia, and nutrient depletion in the tumor microenvironment can alter the antitumor immune response and even promote resistance to immunotherapies such as immune checkpoint blockade and adoptive cell transfer. Although T cells are the primary effectors of the antitumor response, growing evidence demonstrates that innate immune cells are critical to successful tumor clearance. This review aims to summarize current research related to the innate immune system, metabolism, and cancer. We first discuss the specific metabolic requirements of innate immune cells for immune activation and suppression and conclude by highlighting ongoing clinical applications of these findings.

Therapeutic Applications of Type 2 Diabetes Mellitus Drug Metformin in Patients with Osteoarthritis

Type 2 diabetes mellitus (T2DM) and osteoarthritis (OA) are common chronic diseases that frequently co-exist. The link between OA and T2DM is attributed to common risk factors, including age and obesity. Several reports suggest that hyperglycemia and accumulated advanced glycosylation end-products might regulate cartilage homeostasis and contribute to the development and progression of OA. Metformin is used widely as the first-line treatment for T2DM. The drug acts by regulating glucose levels and improving insulin sensitivity. The anti-diabetic effects of metformin are mediated mainly via activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK), which is an energy sensing enzyme activated directly by an increase in the AMP/ATP ratio under conditions of metabolic stress. Dysregulation of AMPK is strongly associated with development of T2DM and metabolic syndrome. In this review, we discuss common risk factors, the association between OA and T2DM, and the role of AMPK. We also address the adaptive use of metformin, a known AMPK activator, as a new drug for treatment of patients with OA and T2DM.

The Effect of Metformin on Survival Outcomes of Non-Metastatic Breast Cancer Patients with Type 2 Diabetes

BACKGROUND

There are still inconsistencies about the role of metformin on breast cancer. This study was designed to assess metformin's effect on the prognosis of female breast cancer patients with type II diabetes.

METHODS

The present research was carried out as a retrospective cohort study between 2003 and 2014. Breast cancer patients with pre-existing type II diabetes mellitus were included. Overall survival (OS) and relapse-free survival (RFS) were measured as the main endpoints. Kaplan-Meier estimate was used to calculate survival rates.

RESULTS

217 patients were included with a mean age of 53.32±11.10 years. 148 (68.2%) patients were prescribed metformin and 69 (31.8%) took other antidiabetic drugs (non-metformin group). Five-year OS and RFS rates for all patients were 82.5% (95% CI: 76.0%-87.4%) and 71.1% (95% CI: 64.2%-77.0%) respectively. Log-rank test showed that the metformin group had a significant advantage over the non-metformin group in terms of both OS and RFS rates (p.

Multidisciplinary management of endocrinopathies and treatment-related toxicities in patients with Bloom syndrome and cancer

The treatment of malignancy in cancer predisposition syndromes that also confer exquisite sensitivity to standard chemotherapy and radiation regimens remains a challenge. Bloom syndrome is one such disorder that is caused by a defect in DNA repair, predisposing to the development of early-onset age-related medical conditions and malignancies. We report on two patients with Bloom syndrome who responded well to chemotherapy despite significant alterations to standard protocols necessitated by hypersensitivity. Both patients experienced severe toxicities and exacerbation of endocrine comorbidities during chemotherapy. A multidisciplinary team of oncologists and endocrinologists is best suited to care for this patient population.

Metformin exhibits antiproliferation activity in breast cancer via miR-483-3p/METTL3/m6A/p21 pathway

Evidence suggests that metformin might be a potential candidate for breast cancer treatment. Yet, its relevant molecular mechanisms remain to be fully investigated. We found that metformin could suppress the N6-methyladenosine (m6A) level in breast cancer cells significantly. The latter has an essential role in breast cancer progression and is newly considered as a therapeutic target. In this study, we measured the m6A level by m6A colorimetric analysis and dot blot assay. We then performed qRT-PCR, western blot, MeRIP, dual-luciferase reporter assay, and others to explore the m6A-dependent pathway associated with metformin. In vivo effect of metformin was investigated using a mouse tumorigenicity model. In addition, breast cancer and normal tissues were used to determine the role of METTL3 in breast cancer. Metformin could reduce the m6A level via decreasing METTL3 expression mediated by miR-483-3p in breast cancer. METTL3 is known to be able to promote breast cancer cell proliferation by regulating the p21 expression by an m6A-dependent manner. Metformin can take p21 as the main target to inhibit such effect. To specify, this study exhibited that metformin can inhibit breast cancer cell proliferation through the pathway miR-483-3p/METTL3/m6A/p21. Our findings suggest that METTL3 may be considered as a potential therapeutic target of metformin for breast cancer.

Metformin promotes innate immunity through a conserved PMK-1/p38 MAPK pathway

Metformin, as the first-line oral drug for type 2 diabetes, has proven benefits against aging, cancer and cardiovascular diseases. But the influence of metformin to the immune response and its molecular mechanisms remain obscure. Metformin increases resistance to not only the Gram-negative pathogens Pseudomonas aeruginosa and Salmonella enterica but also the Gram-positive pathogens Enterococcus faecalis and Staphylococcus aureus. Meanwhile, metformin protects the animals from the infection by enhancing the tolerance to the pathogen infection rather than by reducing the bacterial burden. Through the screening of classical immune pathways in C. elegans, we find metformin enhances innate immunity through p38 MAPK pathway. Furthermore, activated p38/PMK-1 by metformin acts on the intestine for innate immune response. In addition, metformin-treated mice have increased resistance to P. aeruginosa PA14 infection and significantly increased the levels of active PMK-1. Therefore, promoted p38/PMK-1-mediated innate immunity by metformin is conserved from worms to mammals. Our work provides a conserved mechanism by which metformin enhances immune response and boosts its therapeutic application in the treatment of pathogen infection.

Effect of metformin on irinotecan-induced cell cycle arrest in colorectal cancer cell lines HCT116 and SW480

OBJECTIVES

Metformin is widely used for the treatment of type 2 diabetes mellitus and found to have a crucial rule in the induction of apoptosis in several cancer types including pancreatic cell carcinoma, epithelial ovarian cancer, breast cancer, and renal cell carcinoma. In this study, we propose to explore the potential role of metformin as an adjuvant of irinotecan to target colorectal cancer (CRC) cell lines, exploring the effects underlying the anticancer properties of metformin on CRC cell lines.

METHODS

HCT116 and SW480 cell lines were treated with metformin, irinotecan and their combination. The effect of metformin on cell viability was evaluated using MTT assay. Flow cytometry technique was used to analyze apoptosis and cell cycle progression. While, detection of protein expression was analyzed by Western blot.

RESULTS

Metformin was found to inhibit growth in both HCT1116 and SW480 cell lines. On combination with irinotecan, it has been revealed that metformin sensitized CRC cells to irinotecan-induced cytotoxicity. Flow cytometry analysis showed that metformin did not induce apoptosis, but blocked cell cycle in G1 and S phases. This blockage was accompanied by decreased cyclin E and Cdk2 levels and increased p21 level.

CONCLUSION

Combination of metformin with irinotecan may be an effective treatment strategy for targeting colorectal cancer that are resistant to irinotecan monotherapy.

Metformin and ovarian cancer: the evidence

In recent decades, great interest in the off-label use of metformin has arisen as a result of its broad effects on different signaling pathways, with only a few side effects, and low cost. Metformin has been shown to have multiple, dose-dependent preclinical anticancer effects, which can be roughly divided into either direct effects via inhibition of mitochondrial respiratory chain complex I, or indirect effects through lowered glucose, insulin and insulin-like growth factor levels. Further details on in vitro and in vivo anticancer effects specifically in ovarian cancer are continuously reported. Preclinically metformin has clear chemosensitizing effects in ovarian cancer and it is an effective negative regulator of angiogenesis. There are also some epidemiological studies on metformin use in ovarian cancer, but the results of these studies are not as promising as those preclinical studies would indicate. Most preclinical studies have involved metformin concentrations that are many times higher than the pharmacological doses used in patients, which might confound the clinical use of metformin as regards the above-mentioned aspects. In this review we evaluate preclinical and clinical evidence concerning metformin in ovarian cancer treatment.

Metformin inhibits proliferation of oral squamous cell carcinoma cells by suppressing proteolysis of nerve growth factor receptor

OBJECTIVE

We aimed to explore the effects of metformin on oral squamous cell carcinoma (OSCC) cell proliferation and the associated molecular mechanisms.

METHODS

We established an OSCC model in SCC15 cells overexpressing nerve growth factor receptor (NGFR) or the N-terminal region (aa 1-250; NGFR-N), and assessed cell proliferation by CCK-8 assay, colony formation assay, and cell cycle analysis. Levels of NGFR and related genes and proteins were detected by qPCR and western blotting, and NGFR and NGFR-N affinity for p53 was assessed by immunoprecipitation assay. Additionally, the effects of NGFR and NGFR-N on p53 binding with its downstream gene promoters were analyzed by chromatin immunoprecipitation.

RESULTS

Metformin inhibited OSCC cell proliferation and blocked NGFR proteolysis, thereby reducing the generation of its intracellular domain and NGFR-N. Moreover, compared with NGFR, NGFR-N showed higher affinity for p53 and more strongly inactivated p53 to promote cell proliferation. Furthermore, upregulation of NGFR-N downregulated levels of p53-specific downstream transcripts and proteins, whereas these levels were significantly upregulated in metformin-treated cells overexpressing NGFR.

CONCLUSIONS

These results showed that metformin inhibited cell proliferation by suppressing NGFR proteolysis, thereby promoting its antitumor effect in OSCC and offering novel insight into a role for metformin in OSCC treatment.

The potential adjunctive benefit of adding metformin to standard treatment in inoperable cancer patients: a meta-analysis of randomized controlled trials

Background

Recently, there have been several randomized clinical trials (RCTs) conducted to evaluate the efficacy and safety of metformin plus standard treatment in inoperable cancer patients. Our meta-analysis aimed to assess the efficacy of metformin in combination with standard treatment in inoperable cancer patients.

Methods

PubMed and Embase databases were systematically searched for relevant RCTs investigating the efficacy of adding metformin to standard treatment for cancer patients. The pooled relative risk (RR) for tumor response and safety was calculated to assess the efficacy of combining metformin with standard treatment. Meta-analysis was subsequently performed to pool the hazard ratio (HR) for overall survival (OS) and progression-free survival (PFS).

Results

Ten RCTs comprising 1033 patients were included in our current meta-analysis. In patients with breast cancer, results of meta-analysis showed that the addition of metformin to standard treatment was beneficial to objective response rate (ORR) with 30.3% (33/109) in the metformin plus standard treatment group and 16.1% (18/112) in the placebo group (RR 1.92, 95% CI: 1.19–3.10, P=0.008). OS and PFS were not significantly improved in patients who received metformin plus standard treatment compared with those who received placebo plus standard treatment (OS: HR 1.02, 95% CI: 0.71–1.46, P=0.916; PFS: HR 1.14, 95% CI: 0.86–1.50, P=0.366). For lung cancer patients, meta-analysis results showed adding metformin to standard treatment could benefit ORR (metformin 65.3% vs. placebo 54.6%, RR 1.22, 95% CI: 1.03–1.43, P=0.018) with no significant survival benefit in the metformin group. For patients with pancreatic cancer, the pooled ORR was 17.6% (16/91) in metformin plus standard treatment group and 20% (18/90) in the placebo group, indicating metformin did not benefit ORR (RR 0.85, 95% CI: 0.49–1.49, P=0.576). Besides, the addition of metformin to standard treatment did not increase the incidence rate of adverse effects.

Conclusions

Our results indicated that addition of metformin to standard treatment was beneficial to ORR in inoperable breast or lung cancer patients without increasing the incidence of adverse effects. However, adding metformin to standard treatment could not benefit OS and PFS.

Metformin: A Potential Therapeutic Tool for Rheumatologists

Metformin is an oral antihyperglycemic drug widely used to treat type 2 diabetes, acting via indirect activation of 5′ Adenosine Monophosphate-activated Protein Kinase (AMPK). Actually, evidence has accumulated of an intriguing anti-inflammatory activity, mainly mediated by AMPK through a variety of mechanisms such as the inhibition of cytokine-stimulated Nuclear Factor-κB (NF-κB) and the downregulation of the Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) signaling pathways. Moreover, AMPK plays an important role in the modulation of T lymphocytes and other pivotal cells of the innate immune system. The current understanding of these AMPK effects provides a strong rationale for metformin repurposing in the management of autoimmune and inflammatory conditions. Several studies demonstrated metformin’s beneficial effects on both animal and human rheumatologic diseases, especially on rheumatoid arthritis. Unfortunately, even though data are large and remarkable, they almost exclusively come from experimental investigations with only a few from clinical trials. The lack of support from prospective placebo-controlled trials does not allow metformin to enter the therapeutic repertoire of rheumatologists. However, a large proportion of rheumatologic patients can currently benefit from metformin, such as those with concomitant obesity and type 2 diabetes, two conditions strongly associated with rheumatoid arthritis, osteoarthritis, and gout, as well as those with diabetes secondary to steroid therapy.

Therapeutic role of metformin and troglitazone to prevent cancer risk in diabetic patients: evidences from experimental studies

Objectives

It is evident from literature that individual with diabetes mellitus is more prone to develop cancer as compared to non-diabetic one. We aimed to highlight the risk factors that trigger the tumor formation in diabetic individuals and collect evidences regarding the preventive role of anti-diabetics in cancer.

Content

A comprehensive literature was searched in English language using electronic databases including PubMed, ScienceDirect, Medline, Scopus and Embase.

Summary and outlook

Antidiabetic drugs notably metformin and troglitazone, exhibit anticancer effects. Metformin targets energy sensor pathway i. e., AMPK/mTOR which is controlled by LKB1. Whereas. troglitazone activates PPARϒ that modulate the transcription of insulin responsive gene which is essential for lipid and glucose metabolism. Adipocytes are highly expressed with PPARɣ which induce differentiation and regulate adipogenesis. Ligand-driven expression of PPARɣ in myoblast and fibroblast cell lines produces adipocyte differentiation in breast cancer. Prostate cancer that expresses PPARɣ may be suppressed by troglitazone and retinoid which inhibit their proliferation and initiate differentiation. The findings summarized here show that metformin and troglitazone may have the ability to inhibit the cancer cell proliferation via involvement of molecular pathways. This therapeutic intervention will help to control the progression of cancer in diabetic patients.

The impact of adjunctive metformin to progesterone for the treatment of non-atypical endometrial hyperplasia in a randomized fashion, a placebo-controlled, double blind clinical trial

OBJECTIVE

Endometrial hyperplasia (EH) is a premalignant neoplasm. Most recently, metformin has been suggested as an adjuvant medication for treating of EH with better outcome. Recent evidence has suggested that metformin has anticancer activity by inhibiting cell proliferation and tumor growth. The aim of this study was to evaluate the effect of metformin plus megestrol acetate versus megestrol acetate alone on patient with EH without atypia.

STUDY DESIGN

This double blind placebo-controlled clinical trial was conducted among 60 women with EH without atypia. Participants were allocated to two equal groups. Treatment group (M + M) received 40 mg megestrol acetate for 14 days of one month and 1000 mg metformin daily for three months. In placebo group (M + P) each patient received the same dose of megestrol acetate plus two tablets of placebo. Endometrial biopsy was performed in all patients three weeks after the last day of medication RESULTS: Data were evaluated based on 29 and 27 women in the M + M group and M + P group, respectively. After 3 months of therapy 27 (93.1 %) women in M + M group had not EH and responded to treatment, which was statistically higher than the rate of response (19 women, 70.4 %) in M + P group.

CONCLUSIONS

This study showed that megestrol plus metformin was significantly better than megestrol alone for the treatment of endometrial hyperplasia without atypia.

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.

Association between obesity and vulvar cancer recurrence: an analysis of the AGO-CaRE-1 study

OBJECTIVE

Obesity is associated with worse survival and an increased risk of relapse in several malignancies. The influence of obesity on vulvar cancer recurrence has not been previously described. The primary objective of this study was to evaluate the association between obesity and tumor recurrence in patients with vulvar cancer.

METHODS

This is an analysis of the AGO-CaRE-1 study. Patients diagnosed with squamous cell vulvar cancer (stage IB and higher), treated in 29 cancer centers between January 1998 and December 2008, were registered in a centralized database. The cohort was divided into two gropus depending on the body mass index (BMI) (<30 vs ≥30 kg/m²). Descriptive statistics, survival analyses, and multivariate Cox regression analyses were performed in order to evaluate the association between obesity and progression-free and overall survival.

RESULTS

In 849 (52.4%) of 1618 patients in the database, the BMI was documented. Patients were grouped according to their BMI (<30 vs ≥30 kg/m²). There were 621 patients with a BMI <30 kg/m² and 228 patients with a BMI ≥30 kg/m². Besides age, there was no difference in baseline variables (tumor diameter, depth of infiltration, tumor stage, nodal metastasis, tumor grade). Treatment variables (R0 resection, chemotherapy, radiotherapy, continuation of adjuvant therapy) did not differ between groups. However, patients with BMI ≥30 kg/m² underwent radical vulvectomy more often (61.1% vs 51.8%, p=0.04). During follow-up there was a higher recurrence rate in the group with BMI ≥30 kg/m² (43.4% vs 28.3%, p<0.01) due to an increased rate of local recurrences (33.3% vs 18.5%, p<0.01). There was a significantly shorter time to recurrence in obese patients on univariate analysis (BMI ≥30 kg/m² vs <30 kg/m²: 43.8 months (95% CI 23.3 to 64.3) vs 102.3 months (95% CI 72.6 to 131.9), p=0.001) and on multivariate Cox regression analysis (HR 1.94 (95% CI 1.4 to 2.8), p<0.001).

CONCLUSIONS

In this study a BMI ≥30 kg/m² was associated with a shorter time to recurrence in patients with vulvar cancer and this was mainly attributed to a higher risk of local recurrence.

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.

Diabetes: an Overview for Clinical Oncologists

Diabetes and cancer are common conditions highly prevalent in the general population. The co-existence of diabetes and cancer in a patient is therefore not unexpected. Diabetes increases the risk of mortality from cancer and morbidity from the treatment of cancer. Furthermore, many cancer chemotherapeutic regimens increase glucose levels, especially those involving glucocorticoids. Many clinical oncologists will deal with patients with diabetes in their clinical work, and some working knowledge of diabetes diagnosis and management is helpful when managing such patients. This overview aims to summarise the clinical diagnosis and management of diabetes, review the potential links between diabetes and cancer, and provide some practical guidance on the management of hyperglycaemia in patients undergoing cancer therapy.

Adherence to metformin and the onset of rheumatoid arthritis: a population-based cohort study

Objective: The aim of this retrospective cohort study was to examine whether adherence to metformin treatment may be associated with lower onset of rheumatoid arthritis (RA).Method: Using the computerized databases of a 2.3-million state-mandated health services organization in Israel, we identified incident RA cases among a cohort of 113 749 adult patients who initiated metformin therapy between 1998 and 2014. Adherence was assessed by calculating the mean proportion of follow-up days covered (PDC) with metformin.Results: During the 18 year study period, there were 558 incident RA cases (61 per 100 000 person-years). Adherence to metformin treatment was associated with a lower risk of developing RA, with the lowest risk recorded among patients with a PDC of 40-59% [adjusted hazard ratio (HR) 0.62, 95% confidence interval (CI) 0.45-0.84] compared with non-adherent patients (PDC < 20%). A mean daily metformin dose of 2550 mg or more was also associated with a lower risk of developing RA (adjusted HR 0.62, 95% CI 0.46-0.84) compared to a daily dose of 850 mg or less. In stratified analyses by gender, the negative association between adherence and the risk of RA was limited to women alone.Conclusions: Adherence to metformin treatment is associated with a reduced risk of developing RA in women. Further studies are needed to assess the effect of metformin on RA development in other patient populations.

Metformin Treatment for Diabetes Mellitus Correlates with Progression and Survival in Colorectal Carcinoma

BACKGROUND: Diabetes mellitus is unfavorably associated with cancer risk. The purpose of this multidisciplinary project was to evaluate a possible association of diabetes mellitus and other comorbidities and their treatment with progression of colorectal cancer. PATIENTS AND METHODS: We investigated the correlation between pathological characteristics and clinical course, including comorbidities in 1004 Czech patients diagnosed and surgically treated for colorectal adenocarcinoma (CRC) between 1999 and 2016. RESULTS: In our data set, CRC patients treated with metformin due to coexisting diabetes mellitus type 2 (T2DM) developed fewer distant metastases which clinically correlates with slower CRC progression. Survival in metformin subgroup was longer, particularly in men with CRC. Osteoporosis may be a negative factor of survival in CRC patients. CONCLUSIONS: Our findings also indicate that aging, higher tumor grade and TNM stage, coexistence of selected endocrine disorders, and metabolic abnormalities may change the tumor microenvironment and impact survival in colorectal cancer, although mechanism of these observations yet to be explained. Patients with diabetes mellitus type 2 treated with metformin may represent the altered microenvironment with specifically tuned metabolic molecular responses and with various epigenetic characteristics. More awareness and increased understanding of the mechanisms underlying the positive effect of metformin on patients' survival could offer insight into new treatment methods and permit more individualized treatment plans.

Metformin inhibits human spermatozoa motility and signalling pathways mediated by protein kinase A and tyrosine phosphorylation without affecting mitochondrial function

Metformin is a leading antidiabetic drug that is used worldwide in the treatment of diabetes mellitus. This biguanide exerts metabolic and pleiotropic effects in somatic cells, although its invitro actions on human spermatozoa remain unknown. The present study investigated the effects of metformin on human sperm function. Human spermatozoa were incubated in the presence or absence of 10mM metformin for 8 or 20h, and motility was measured by computer-aided sperm analysis (CASA); other parameters were evaluated by flow cytometry. Metformin significantly reduced the percentage of motile, progressive and rapid spermatozoa and significantly decreased sperm velocity. Metformin did not affect viability, mitochondrial membrane potential (MMP) or mitochondrial superoxide anion generation of human spermatozoa at any time studied. However, metformin clearly inhibited the protein kinase (PK) A pathway and protein tyrosine phosphorylation at 8 and 20h, key regulatory pathways for correct sperm function. In summary, metformin treatment of human spermatozoa had a detrimental effect on motility and inhibited essential sperm signalling pathways, namely PKA and protein tyrosine phosphorylation, without affecting physiological parameters (viability, MMP, mitochondrial superoxide anion generation). Given the growing clinical use of metformin in different pathologies in addition to diabetes, this study highlights an adverse effect of metformin on spermatozoa and its relevance in terms of human fertility in patients who potentially could be treated with metformin in the future.

Exposing the Underlying Relationship of Cancer Metastasis to Metabolism and Epithelial-Mesenchymal Transitions

Cancer is a disease governed by the underlying gene regulatory networks. The hallmarks of cancer have been proposed to characterize the cancerization, e.g., abnormal metabolism, epithelial to mesenchymal transition (EMT), and cancer metastasis. We constructed a metabolism-EMT-metastasis regulatory network and quantified its underlying landscape. We identified four attractors, characterizing epithelial, abnormal metabolic, mesenchymal, and metastatic cell states, respectively. Importantly, we identified an abnormal metabolic state. Based on the transition path theory, we quantified the kinetic transition paths among these different cell states. Our results for landscape and paths indicate that metastasis is a sequential process: cells tend to first change their metabolism, then activate the EMT and eventually reach the metastatic state. This demonstrates the importance of the temporal order for different gene circuits switching on or off during metastatic progression of cancer cells and underlines the cascading regulation of metastasis through an abnormal metabolic intermediate state.

The anti-cancer effects of phenformin in thyroid cancer cell lines and in normal thyrocytes

Phenformin is a biguanide drug which, besides the original anti-diabetic effect, also exerts anti-cancer effects. The aim of this study was to further characterize these latter in terms of both cell-viability and modulation of the secretion of the pro-tumorigenic chemokine CXCL8. Normal human thyrocytes in primary cultures (NHT) and thyroid cancer cell lines, TPC-1 and 8505C (RET/PTC and BRAFV600E mutated, respectively) were treated with increasing concentrations of phenformin at different times. Cell-viability was assessed by WST-1 and further characterized by AnnexinV/PI staining and cell proliferation colony-assay. CXCL8 levels were measured in cell supernatants. Phenformin reduced cell-viability in TPC-1 and 8505C and their ability to form colonies. In NHT cells, phenformin affected cell-viability only at the maximal dose but interestingly it inhibited CXCL8 secretion at all the concentrations not affecting cell-viability. Phenformin had no effect on CXCL8 secretion in thyroid cancer cell lines. Thus, phenformin exerts anti-cancer effects on both cancer cells (cell death induction) and surrounding normal cells (inhibition of CXCL8 secretion). These results highlight that the anti-cancer effects of phenformin are multifaceted and effective on both solid and soluble components of the tumor-microenvironment.

Inhibition of midkine by metformin can contribute to its anticancer effects in malignancies: A proposal mechanism of action of metformin in context of endometrial cancer prevention and therapy

Metformin, a drug widely used in the treatment of type II diabetes mellitus (T2DM), has been the focus of interest as a potential therapeutic agent for certain types of malignancies, including gynaecological cancers [i.e. endometrial cancer (EC)]. Although the exact mechanism behind the potential anticancer activity of metformin is still not completely understood, certain studies have suggested that different effects on cell functions, such as inhibition of cell migration, apoptosis and tumor cell proliferation, are involved in its preventive and therapeutic effects in certain types of malignancies, including EC. In contrast, midkine (MK), a heparin-binding growth factor and cytokine, which induces carcinogenesis and chemoresistance, promotes the development and progression of many malignant tumours by increasing diverse cell functions such as cell proliferation, cell survival and antiapoptotic activities via mainly the activation of phosphatidyl inositol 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways. The same pathways are also subject to certain therapeutic effects of metformin, although this cytokine and this drug have some different mechanism of action pathways as well. Taken together, MK and metformin appear to have opposite effects in various biological processes such as apoptosis, cell proliferation, cell survival, cell migration, and angiogenesis. On the other hand, MK activates PI3K and MAPK cell signal pathways, whereas metformin inhibits these two pathways. It seems likely that almost all the pathways and cell functions, which play important roles in malignancies, are inhibited by metformin and activated by MK. Given the opposite relationship between the actions of metformin and MK, we hypothesize that metformin may act like a novel MK inhibitor in some malignancies. We also discuss the possible relationship between metformin and MK in the context of EC, the most common gynecological cancer worldwide, which incidence is rising rapidly, in parallel with the increase in obesity, T2DM and insulin resistance. In this respect, the therapeutic use of metformin may improve the survival of EC or other cancers, via inhibiting or overcoming the unwanted effects of MK in carcinogenesis.

mTOR as a central regulator of lifespan and aging

The mammalian/mechanistic target of rapamycin (mTOR) is a key component of cellular metabolism that integrates nutrient sensing with cellular processes that fuel cell growth and proliferation. Although the involvement of the mTOR pathway in regulating life span and aging has been studied extensively in the last decade, the underpinning mechanisms remain elusive. In this review, we highlight the emerging insights that link mTOR to various processes related to aging, such as nutrient sensing, maintenance of proteostasis, autophagy, mitochondrial dysfunction, cellular senescence, and decline in stem cell function.

Metformin for lung cancer prevention and improved survival: a novel approach

Diabetes mellitus has been associated with increased risk for the development of many types of cancer. Metformin, an oral medication and first-line treatment for type 2 diabetes mellitus, has been suggested to reduce cancer risk and mortality in various types of cancer. This study focuses on assessing metformin association with lung cancer as reported in the literature. Recent studies and reviews investigating metformin effects on lung cancer incidence and patient survival are critically and systematically discussed.

Nutraceuticals and "Repurposed" Drugs of Phytochemical Origin in Prevention and Interception of Chronic Degenerative Diseases and Cancer

BACKGROUND

Chronic, degenerative diseases are often characterized by inflammation and aberrant angiogenesis. For these pathologies, including rheumatoid arthritis, cardiovascular and autoimmune diseases, cancer, diabetes, and obesity, current therapies have limited efficacy.

OBJECTIVES

The validation of novel (chemo)preventive and interceptive approaches, and the use of new or repurposed agents, alone or in combination with registered drugs, are urgently required.

RESULTS

Phytochemicals (triterpenoids, flavonoids, retinoids) and their derivatives, nonsteroidal anti-inflammatory drugs (aspirin) as well as biguanides (metformin and phenformin) originally developed from phytochemical backbones, are multi-target agents showing antiangiogenic and anti-anti-inflammatory proprieties. Many of them target AMPK and metabolic pathways such as the mTOR axis. We summarize the beneficial effects of several compounds in conferring protection and supporting therapy, and as a paradigm, we present data on terpenoids & biquanides on beer hop xanthohumol and hydroxytryrosol from olive mill waste waters.

CONCLUSIONS

These molecules could be employed for combinatorial chemoprevention and interception approaches or chemoprevention/therapy regimens for cancer and other chronic complex diseases.

A Cohort Study of Metformin and Colorectal Cancer Risk among Patients with Diabetes Mellitus

Background: Several epidemiologic studies have reported strong inverse associations between metformin use and risk of colorectal cancer, although time-related biases, such as immortal time bias, may in part explain these findings. We reexamined this association using methods to minimize these biases.Methods: A cohort study was conducted among 47,351 members of Kaiser Permanente Northern California with diabetes and no history of cancer or metformin use. Follow-up for incident colorectal cancer occurred from January 1, 1997, until June 30, 2012. Cox regression was used to calculate HRs and 95% confidence intervals (CIs) for colorectal cancer risk associated with metformin use (ever use, total duration, recency of use, and cumulative dose).Results: No association was observed between ever use of metformin and colorectal cancer risk (HR, 0.90; 95% CI, 0.76-1.07) and there was no consistent pattern of decreasing risk with increasing total duration, dose, or recency of use. However, long-term use (≥5.0 years) appeared to be associated with reduced risk of colorectal cancer in the full population (HR, 0.78; 95% CI, 0.60-1.02), among current users (HR, 0.78; 95% CI, 0.59-1.04), and in men (HR, 0.65; 95% CI, 0.45-0.94) but not in women. Higher cumulative doses of metformin were associated with reduced risk. In initial users of sulfonylureas, switching to or adding metformin was also associated with decreased colorectal cancer risk.Conclusions: Our findings showed an inverse association between long-term use of metformin and colorectal cancer risk. Findings, especially the risk reduction among men, need to be confirmed in large, well-conducted studies.Impact: If our findings are confirmed, metformin may have a role in the chemoprevention of colorectal cancer. Cancer Epidemiol Biomarkers Prev; 27(5); 525-30. ©2018 AACRSee related commentary by Jackson and García-Albéniz, p. 520.

The beneficial effects of metformin on cancer prevention and therapy: a comprehensive review of recent advances

Metformin is a widely used drug in today’s prescriptions by physicians due to its specific effects in treating and curing type II diabetes. Diabetes is a common disease that may occur throughout human life, and can increase the likelihood of the occurrence of various types of cancer, such as colon, rectum, pancreas and liver cancers, compared to non-diabetic patients. Metformin inhibits mTOR activity by activating ATM (ataxia telangiectasia mutated) and LKB1 (liver kinase B1) and then adenosine monophosphate-activated kinase (AMPK), and thus prevents protein synthesis and cell growth. Metformin can activate p53 by activating AMPK and thereby ultimately stop the cell cycle. Given the potential of metformin in the treatment of cancer, it can be used in radiotherapy, chemotherapy and to improve the response to treatment in androgen derivatives (ADT), and also, according to available evidence, metformin can also be used to prevent various types of cancers. Generally, metformin can: 1) reduce the incidence of cancers, 2) reduce the mortality from cancers, 3) increase the response to treatment in cancer cells when using radiotherapy and chemotherapy, 4) optimize tumor movement and reduce the malignancy, 5) reduce the likelihood of relapse, and 6) reduce the damaging effects of ADT. Therefore, this drug can be used as a complementary therapeutic agent for cancer treatment and prevention. In this review, we have summarized the data from various experimental and clinical studies and highlight the possible potential effects of metformin on cancer therapeutic responses.

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Diabetes Medication Use in Association with Survival among Patients of Breast, Colorectal, Lung, or Gastric Cancer

PURPOSE

Studies suggest that regular use of metformin may decrease cancer mortality. We investigated the association between diabetes medication use and cancer survival.

MATERIALS AND METHODS

The current study includes 633 breast, 890 colorectal, 824 lung, and 543 gastric cancer cases identified from participants of two population-based cohort studies in Shanghai. Information on diabetes medication use was obtained by linking to electronic medical records. The associations between diabetes medication use (metformin, sulfonylureas, and insulin) and overall and cancer-specific survival were evaluated using time-dependent Cox proportional hazards models.

RESULTS

After adjustment for clinical characteristics and treatment factors, use of metformin was associated with better overall survival among colorectal cancer patients (hazards ratio [HR], 0.55; 95% confidence interval [CI], 0.34 to 0.88) and for all four types of cancer combined (HR, 0.75; 95% CI, 0.57 to 0.98). Ever use of insulin was associated with worse survival for all cancer types combined (HR, 1.89; 95% CI, 1.57 to 2.29) and for the four cancer types individually. Similar associations were seen for diabetic patients. Sulfonylureas use was associated with worse overall survival for breast or gastric cancer (HR, 2.87; 95% CI, 1.22 to 6.80 and HR, 2.05; 95% CI, 1.09 to 3.84, respectively) among diabetic patients. Similar association patterns were observed between diabetes medication use and cancer-specific survival.

CONCLUSION

Metformin was associated with improved survival among colorectal cancer cases, while insulin use was associated with worse survival among patients of four major cancers. Further investigation on the topic is needed given the potential translational impact of these findings.

The C Allele of ATM rs11212617 Associates With Higher Pathological Complete Remission Rate in Breast Cancer Patients Treated With Neoadjuvant Metformin

Background: The minor allele (C) of the single-nucleotide polymorphism (SNP) rs11212617, located near the ataxia telangiectasia mutated (ATM) gene, has been associated with an increased likelihood of treatment success with metformin in type 2 diabetes. We herein investigated whether the same SNP would predict clinical response to neoadjuvant metformin in women with early breast cancer (BC). Methods: DNA was collected from 79 patients included in the intention-to-treat population of the METTEN study, a phase 2 clinical trial of HER2-positive BC patients randomized to receive either metformin combined with anthracycline/taxane-based chemotherapy and trastuzumab or equivalent regimen without metformin, before surgery. SNP rs11212617 genotyping was assessed using allelic discrimination by quantitative polymerase chain reaction. Results: Logistic regression analyses revealed a significant relationship between the rs11212617 genotype and the ability of treatment arms to achieve a pathological complete response (pCR) in patients (odds ratio [OR]_{genotype×arm} = 10.33, 95% confidence interval [CI]: 1.29-82.89, p = 0.028). In the metformin-containing arm, patients bearing the rs11212617 C allele had a significantly higher probability of pCR (OR _A/C,C/C = 7.94, 95%CI: 1.60-39.42, p = 0.011). Conversely, no association was found between rs11212617 and clinical response in the reference arm (OR _A/C,C/C = 0.77, 95%CI: 0.20-2.92, p = 0.700). After controlling for tumor size and hormone receptor status, the rs11212617 C allele remained a significant predictor of pCR solely in the metformin-containing arm. Conclusions: If reproducible, the rs11212617 C allele might warrant consideration as a predictive clinical biomarker to inform the personalized use of metformin in BC patients. Trial Registration: EU Clinical Trials Register, EudraCT number 2011-000490-30. Registered 28 February 2011, https://www.clinicaltrialsregister.eu/ctr-search/trial/2011-000490-30/ES.

Combination of metformin and paclitaxel suppresses proliferation and induces apoptosis of human prostate cancer cells via oxidative stress and targeting the mitochondria-dependent pathway

Previous studies have reported that metformin (MET) has anticancer activity. In combination with chemotherapeutic drugs, MET reduces the dosage of chemotherapeutic drugs required and enhances anticancer efficacy. In the present study, the combination of MET and paclitaxel (PTX) in three human prostate cancer (PCa) cell lines (22RV1, PC-3 and LNCaP) was evaluated to investigate the effects on proliferation and apoptosis of PCa cells. The present study explored whether their effects were associated with reactive oxygen species (ROS). An MTT assay and microscopy were used to study the effect of MET + PTX on cell growth. Half maximal inhibitory concentration (IC₅₀) values were obtained for MET (12.281±1.089 mM for 22RV1, 2.248±0.352 mM for PC-3 cells and 3.610±0.577 mM for LNCaP cells) and PTX (13.170±1.12 nM for PC-3 cells) at 48 h. Since the survival rate of 22RV1 and LNCaP cells did not decrease linearly with increasing PTX concentration, it is difficult to estimate accurate IC₅₀; therefore, only IC₅₀ values for PTX in PC-3 cells were given. When treating the cells with 5 mM MET, the IC₅₀ of PTX decreased to 5.423±0.734 nM for PC-3 cells. Annexin V and propidium iodide staining was used to investigate apoptosis by flow cytometry. The apoptotic mechanisms of MET + PTX in PCa were investigated by detecting the expression of apoptosis-related proteins, activities of caspase-3/7, intracellular ROS accumulation, mitochondrial membrane potential, and intracellular levels of adenosine 5′-triphosphate (ATP). MET + PTX induced PCa apoptosis and ROS accumulation, and decreased mitochondrial membrane potential and intracellular levels of ATP. Taken together, these results indicated that MET + PTX suppressed PCa cell proliferation in a dose- and time-dependent manner. In addition, MET + PTX induced apoptosis by increasing ROS levels, reducing mitochondrial membrane potential, and activating mitochondrial-dependent apoptotic pathways.

Metformin Reduces Renal Uptake of Radiotracers and Protects Kidneys from Radiation-Induced Damage

Metformin is the most widely prescribed drug for type 2 diabetes. Chemically, metformin is a hydrophilic base that functions as an organic cation, suggesting that it may have the capacity to inhibit the tubular reabsorption of peptide radiotracers. The purpose of this study was to investigate whether metformin could reduce renal uptake of peptidyl radiotracers and serve as a radioprotective agent for peptide receptor radionuclide therapy (PRRT).

METHODS

We used two radiolabeled peptides: a ⁶⁸Ga-labeled cyclic (TNYL-RAW) peptide (⁶⁸Ga-NOTA-c(TNYL-RAW) (NOTA: 1,4,7 triazacyclononane-1,4,7-trisacetic acid) targeting EphB4 receptors and an ¹¹¹In- or ⁶⁴Cu-labeled octreotide (¹¹¹In/⁶⁴Cu-DOTA-octreotide) (DOTA: 1,4,7,10 triazacyclododecane-1,4,7,10-tetraacetic acid) targeting somatostatin receptors. Each radiotracer was injected intravenously into normal Swiss mice or tumor-bearing nude mice in the presence or absence of metformin administered intravenously or orally. Micropositron emission tomography or microsingle-photon emission computed tomography images were acquired at different times after radiotracer injection, and biodistribution studies were performed at the end of the imaging session. To assess the radioprotective effect of metformin on the kidneys, normal Swiss mice received two doses of ¹¹¹In-DOTA-octreotidein the presence or absence of metformin, and renal function was analyzed via blood chemistry and histology.

RESULTS

Intravenous injection of metformin with ⁶⁸Ga-NOTA-c(TNYL-RAW) or ¹¹¹In-DOTA-octreotide reduced the renal uptake of the radiotracer by 60% and 35%, respectively, compared to uptake without metformin. These reductions were accompanied by greater uptake in the tumors for both radiolabeled peptides. Moreover, the renal uptake of ¹¹¹In-DOTA-octreotide was significantly reduced when metformin was administered via oral gavage. Significantly more radioactivity was recovered in the urine collected over a period of 24 h after intravenous injection of ⁶⁴Cu-DOTA-octreotide in mice that received oral metformin than in mice that received vehicle. Finally, coadministration of ¹¹¹In-DOTA-octreotide with metformin mitigated radio-nephrotoxicity.

CONCLUSION

Metformin inhibits kidney uptake of peptidyl radiotracers, protecting the kidney from nephrotoxicity. Further studies are needed to elucidate the mechanisms of these finding and to optimize mitigation of radiation-induced damage to kidney in PRRT.

Metformin selectively targets 4T1 tumorspheres and enhances the antitumor effects of doxorubicin by downregulating the AKT and STAT3 signaling pathways

Recent studies have reported that metformin (Met), the first-line medication for the treatment of type 2 diabetes, exhibited anticancer and chemoprotective effects in diverse cancer cells. In this study, we investigated the effects of Met on the drug-resistance of 4T1 murine breast cancer tumorspheres (TS) and the mechanism responsible for its drug-resistance. 4T1 TS exhibited accumulations of cells at the G₀/G₁ phase compared with cells in monolayer culture, which suggested the majority of cells in TS were quiescent. Furthermore, it was identified that activations of the signal transducer and activator of transcription 3 (STAT3) and protein kinase B (AKT) signaling pathways in 4T1 TS conferred drug-resistance to doxorubicin (Dox) and lapatinib (Lapa). However, Met selectively targeted TS rather than cells in monolayer culture and increased the cytotoxic effect of Dox on TS by inhibiting activations of the STAT3 and AKT signaling pathways. These observations suggested that inhibitions of STAT3 and AKT underlie the selective cytotoxic effects of Met on TS. In addition, Met exhibited synergistic antitumor effects with Dox on 4T1 tumor-bearing BALB/c mice. Our findings suggest that combinations of Met and cytotoxic anticancer drugs may offer an advantage for treating drug-resistant breast cancer.

Emerging Anti-Aging Strategies - Scientific Basis and Efficacy

The prevalence of age-related diseases is in an upward trend due to increased life expectancy in humans. Age-related conditions are among the leading causes of morbidity and death worldwide currently. Therefore, there is an urgent need to find apt interventions that slow down aging and reduce or postpone the incidence of debilitating age-related diseases. This review discusses the efficacy of emerging anti-aging approaches for maintaining better health in old age. There are many anti-aging strategies in development, which include procedures such as augmentation of autophagy, elimination of senescent cells, transfusion of plasma from young blood, intermittent fasting, enhancement of adult neurogenesis, physical exercise, antioxidant intake, and stem cell therapy. Multiple pre-clinical studies suggest that administration of autophagy enhancers, senolytic drugs, plasma from young blood, drugs that enhance neurogenesis and BDNF are promising approaches to sustain normal health during aging and also to postpone age-related neurodegenerative diseases such as Alzheimer's disease. Stem cell therapy has also shown promise for improving regeneration and function of the aged or Alzheimer's disease brain. Several of these approaches are awaiting critical appraisal in clinical trials to determine their long-term efficacy and possible adverse effects. On the other hand, procedures such as intermittent fasting, physical exercise, intake of antioxidants such as resveratrol and curcumin have shown considerable promise for improving function in aging, some of which are ready for large-scale clinical trials, as they are non-invasive, and seem to have minimal side effects. In summary, several approaches are at the forefront of becoming mainstream therapies for combating aging and postponing age-related diseases in the coming years.

Risk of colon cancer recurrence in relation to diabetes

PURPOSE

To describe the association between diabetes and colon cancer recurrence.

METHODS

We conducted a cohort study at two integrated health care delivery systems in the United States. Using tumor registry data, we identified patients aged ≥ 18 years when diagnosed with stage I-IIIA adenocarcinomas of the colon during 1995-2014. Pre-existing diabetes was ascertained via diagnosis codes. Medical records were reviewed for eligibility and to abstract recurrence and covariate information. Recurrence was ascertained beginning 90 days after the end of colon cancer treatment (i.e., cohort entry). Recurrence of any cancer or a new primary cancer at any site was a secondary outcome. We used multivariable Cox proportional hazards models to estimate hazard ratios (HR) and 95% confidence intervals (CIs) for the associations between diabetes at cohort entry and study outcomes.

RESULTS

Among the 1,923 eligible patients, 393 (16.7%) had diabetes at cohort entry. Diabetes was not associated with recurrence (HR 0.87; 95% CI 0.56-1.33) or with any subsequent cancer (HR 1.09; 95% CI 0.85-1.40). When the definition of recurrence included second primary colorectal cancer, risk was non-significantly higher in patients with diabetes than without diabetes.

CONCLUSIONS

The risk of colon cancer recurrence appears to be similar in patients with and without diabetes at diagnosis.

IMPACT

Future studies should evaluate the association between diabetes and colorectal cancer outcomes, especially second primary colon cancers, in larger populations.

Effects of metformin treatment on radiotherapy efficacy in patients with cancer and diabetes: a systematic review and meta-analysis

Purpose

Metformin is a key pharmaceutical for patients with diabetes mellitus (DM). Metformin also can enhance tumor radiosensitivity in vitro and in vivo. Some retrospective cohort studies have indicated that metformin can improve the efficacy of radiotherapy in patients with cancer and DM. The aim of this systematic review was to evaluate the radiotherapy efficacy of metformin in patients with cancer and DM.

Methods

Multiple databases were queried for studies that address the efficacy of metformin in radiotherapy of patients with cancer and DM. Studies were included that involved comparisons of the short-term tumor responses and long-term survival outcomes of these patients who were managed with or without metformin as well as of nondiabetic patients without metformin. The OR and HR with accompanying 95% CI were assessed in a random effects model. The main endpoints were 2-year and 5-year overall survival (2y-OS and 5y-OS, respectively).

Results

The database search yielded 17 cohort studies that met the inclusion criteria. The results indicated that the tumor response was higher in patients who also were treated with metformin than in those who were not (OR, 0.48; 95% CI, 0.22-1.07; P=0.07) and nondiabetic (OR, 0.27; 95% CI, 0.07-0.98; P=0.05). Moreover, patients who received metformin had survival benefits compared with patients not treated with metformin (2y-OS: OR, 0.48; 95% CI, 0.29-0.80; P=0.005; 5y-OS: OR, 0.38; 95% CI, 0.25-0.56; P<0.00001). The metformin-related HRs of OS values were not significantly different.

Conclusion

Metformin appears to improve the tumor response to radiotherapy in patients with cancer and DM and partly yield survival benefits. Despite the apparent advantages provided by metformin treatment on 2y-OS and 5y-OS, these retrospective data are at risk of bias and should be interpreted with caution.

Metabolic Effects of Metformin in the Failing Heart

Accumulating evidence shows that metformin is an insulin-sensitizing antidiabetic drug widely used in the treatment of type 2 diabetes mellitus (T2DM), which can exert favorable effects on cardiovascular risk and may be safely used in patients with heart failure (HF), and even able to reduce the incidence of HF and to reduce HF mortality. In failing hearts, metformin improves myocardial energy metabolic status through the activation of AMP (adenosine monophosphate)-activated protein kinase (AMPK) and the regulation of lipid and glucose metabolism. By increasing nitric oxide (NO) bioavailability, limiting interstitial fibrosis, reducing the deposition of advanced glycation end-products (AGEs), and inhibiting myocardial cell apoptosis metformin reduces cardiac remodeling and hypertrophy, and thereby preserves left ventricular systolic and diastolic functions. While a lot of preclinical and clinical studies showed the cardiovascular safety of metformin therapy in diabetic patients and HF, to confirm observed benefits, the specific large-scale trials configured for HF development in diabetic patients as a primary endpoints are necessary.

Repurposing old drugs in oncology: Opportunities with clinical and regulatory challenges ahead

WHAT IS KNOWN AND OBJECTIVE

In order to expedite the availability of drugs to treat cancers in a cost-effective manner, repurposing of old drugs for oncological indications is gathering momentum. Revolutionary advances in pharmacology and genomics have demonstrated many old drugs to have activity at novel antioncogenic pharmacological targets. We decided to investigate whether prospective studies support the promises of nonclinical and retrospective clinical studies on repurposing three old drugs, namely metformin, valproate and astemizole.

METHODS

We conducted an extensive literature search through PubMed to gather representative nonclinical and retrospective clinical studies that investigated the potential repurposing of these three drugs for oncological indications. We then searched for prospective studies aimed at confirming the promises of retrospective data.

RESULTS AND DISCUSSION

While evidence from nonclinical and retrospective clinical studies with these drugs appears highly promising, large scale prospective studies are either lacking or have failed to substantiate this promise. We provide a brief discussion of some of the challenges in repurposing. Principal challenges and obstacles relate to heterogeneity of cancers studied without considering their molecular signatures, trials with small sample size and short duration, failure consider issues of ethnicity of study population and effective antioncogenic doses of the drug studied.

WHAT IS NEW AND CONCLUSION

Well-designed prospective studies demonstrating efficacy are required for repurposing old drugs for oncology indications, just as they are for new chemical entities for any indication. Early and ongoing interactions with regulatory authorities are invaluable. We outline a tentative framework for a structured approach to repurposing old drugs for novel indications in oncology.

A Ketogenic Diet Reduces Central Obesity and Serum Insulin in Women with Ovarian or Endometrial Cancer

Background

The glycolytic nature of cancer cells presents a potential treatment target that may be addressed by a ketogenic diet (KD).

Objective

We hypothesized that a KD would improve body composition and lower serum insulin and insulin-like growth factor-I (IGF-I) in women with ovarian or endometrial cancer.

Methods

In this randomized controlled trial, women with ovarian or endometrial cancer [age: ≥19 y; body mass index (kg/m2): ≥18.5] were randomly assigned to a KD (70:25:5 energy from fat, protein, and carbohydrate) or the American Cancer Society diet (ACS; high-fiber, low-fat). Body composition (DXA) and fasting serum insulin, IGF-I, and β-hydroxybutyrate were obtained at baseline and at 12 wk; urinary ketones were also measured throughout the intervention. We assessed differences between the diets with ANCOVA and independent t tests. We used correlation analyses to estimate associations between changes in serum analytes and body composition.

Results

After 12 wk, the KD (compared with ACS) group had lower adjusted total (35.3 compared with 38.0 kg, P < 0.05) and android (3.0 compared with 3.3 kg, P < 0.05) fat mass. Percentage of change in visceral fat was greater in the KD group (compared with the ACS group; -21.2% compared with -4.6%, P < 0.05). Adjusted total lean mass did not differ between the groups. The KD (compared with ACS) group had lower adjusted fasting serum insulin (7.6 compared with 11.2 µU/mL, P < 0.01). There was a significant inverse association between the changes in serum β-hydroxybutyrate and IGF-I concentrations (r = -0.57; P < 0.0001).

Conclusions

In women with ovarian or endometrial cancer, a KD results in selective loss of fat mass and retention of lean mass. Visceral fat mass and fasting serum insulin also are reduced by the KD, perhaps owing to enhanced insulin sensitivity. Elevated serum β-hydroxybutyrate may reflect a metabolic environment inhospitable to cancer proliferation. This trial was registered at www.clinicaltrials.gov as NCT03171506.

A hypothetical method for controlling highly glycolytic cancers and metastases

Most proliferating cancer cells and cancer-associated tumor stroma have an upregulated glucose energy demand in relation to normal cells. Cancer cells are further less metabolically flexible than normal cells. They can therefore not survive metabolic stress as well as normal cells can. Metabolic deprivation thus provides a potential therapeutic window. Unfortunately, current glucose blockers have toxicity problems. An alternative way to reduce a cancer patient's blood glucose (BG), for a short-term period to very low levels, without the concomitant toxicity, is hypothesized in this paper. In vitro tests have shown that short-term BG deprivation to 2 mmol/L for 180 min is an effective cancer treatment. This level of hypoglycaemia can be maintained in vivo with a combination of very low-dose insulin and the suppression of the glucose counter-regulation system. Such suppression can be safely achieved by the infusion of somatostatin and a combination of both α and β-blockers. The proposed short-term in vivo method, was shown to be non-toxic and safe for non-cancer patients. The next step is to test the effect of the proposed method on cancer patients. It is also suggested to incorporate well-known, long-term BG deprivation treatments to achieve maximum effect.

Effect of Metformin and Statin Use on Survival in Pancreatic Cancer Patients: a Systematic Literature Review and Meta-analysis

BACKGROUND AND OBJECTIVE

Current epidemiological studies report conflicting results for the effect of statin or metformin on pancreatic cancer overall survival. This literature review and meta-analysis summarize the studies reporting an association between statin or metformin use and overall survival of pancreatic cancer patients.

METHODS

We systematically searched for studies about the association between statin or metformin use and pancreatic cancer overall survival in electronic databases (PubMed, ISI Web of Science, MEDLINE, Cochrane, Scopus, Google Scholar). A meta-analysis based on hazard ratios (HRs) and 95% confidence intervals (CIs) was performed using random effect models. Heterogeneity between the studies was examined using I2 statistics, and sensitivity analyses were conducted to assess the robustness of the findings.

RESULTS

Of 116 statin-related articles identified, 6 retrospective cohort studies representing 12,057 patients were included. There was significant heterogeneity between studies. Statin use was associated with improved survival among pancreatic cancer patients (meta-HR = 0.75; 95% CI: 0.59, 0.90; P < 0.001). Of 311 metformin-related articles, 8 retrospective cohort studies and 2 randomized clinical trials, representing 3,042 patients were identified. Metformin use was associated with better overall survival among pancreatic cancer patients (meta-HR = 0.79; 95% CI: 0.70, 0.92, P < 0.001), and significant heterogeneity was observed between studies.

CONCLUSION

Our findings suggest that the improved survival time of pancreatic cancer patients are associated with statin or metformin use. Due to the multiple sources of heterogeneity of the original studies, these findings should be considered cautiously, and confirmed with larger prospective individual-level studies.

Protective Effect of Metformin Against Thyroid Cancer Development: A Population-Based Study in Korea

BACKGROUND

Metformin, the most widely used drug for type 2 diabetes, has recently attracted attention with regard to its antitumor activity. However, clinical studies have yielded conflicting results regarding the association between metformin and thyroid cancer development, despite its antitumor effect in preclinical studies.

METHODS

This is a retrospective cohort study using the Korean National Health Insurance claim database. Matched populations of 128,453 metformin users and 128,453 non-users were analyzed for thyroid cancer incidence. Metformin users were categorized into lowest, middle, and highest tertiles according to cumulative dose or duration of metformin therapy.

RESULTS

Thyroid cancer developed in 340 (0.26%) metformin users and 487 (0.38%) non-users during a mean follow-up of 7.2 years (hazard ratio = 0.69 [confidence interval 0.60-0.79]; p < 0.001). The incidence of thyroid cancer per 10⁵ person-years was 51.6 in metformin non-users. For metformin users, the incidence was 84.5 for <529,000 mg, 20.6 for 529,000-1,007,799 mg, and 6.3 for >1,007,799 mg; 86.3 for <1085 days, 20.3 for 1085-2094 days, and 4.7 for >2094 days for duration of therapy. The hazard ratio for thyroid cancer decreased significantly in metformin users as a function of dose and duration of metformin therapy.

CONCLUSIONS

Metformin appears to be associated with a preventive effect on thyroid cancer development in a nationwide population-based study, but is not effective in the early phase of treatment. Considering the increasing prevalence of obesity and the role of insulin resistance in the development of cancer, metformin might be the preferred treatment for its dual anti-diabetic and antitumor effects.

Metformin prevents nerve growth factor-dependent proliferative and proangiogenic effects in epithelial ovarian cancer cells and endothelial cells

Background

Epithelial ovarian cancer (EOC) is characterized by exacerbated angiogenesis regulated by proangiogenic and growth factors. Nerve growth factor (NGF) is overexpressed in EOC where it promotes proliferation as well as survival and is considered a proangiogenic factor. Metformin, a drug commonly used in the treatment of diabetes, is attributed to antineoplastic effects, but the underlying mechanisms remain unknown. Given that current therapies yield modest results in EOC patients, the aim of this study was to determine the effects of metformin on NGF-enhanced proliferation of EOC cells and the angiogenic potential of endothelial cells.

Methods

A2780 (EOC), HOSE (human ovarian surface epithelial) and EA.hy926 (endothelial) cells were treated with NGF and metformin. Cell viability, cell proliferation and cell cycle were evaluated in all three cell lines, and the angiogenic potential in endothelial EA.hy926 cells.

Results

NGF enhanced cell proliferation in A2780, HOSE and EA.hy926 cells (p < 0.05), while metformin treatment decreased cell proliferation in A2780 and EA.hy926 cells (p < 0.05). Moreover, the NGF-enhanced angiogenic score in EA.hy926 cells was prevented by metformin (p < 0.05).

Conclusions

Given that NGF plays a significant role in EOC progression, our current findings suggest that metformin holds considerable promise as an adjuvant treatment in ovarian cancer.