Diabetes, antihyperglycemic medications and cancer risk: smoke or fire?

Diabetes and ovarian cancer: risk factors, molecular mechanisms and impact on prognosis

BACKGROUND AND AIM

Diabetes mellitus has been linked to a lower rate of cancer survival and an increase in the incidence of most malignancies. Investigations showed that diabetes might affect ovarian cancer (OC) prognosis and survival. Based on the current information, this study intends to review the risk factors, molecular pathways, and impact of diabetes on OC.

METHODS

The data was derived from online databases, including Web of Science, PubMed, and Scopus. The inclusion criteria were original studies, which included the risk factors, molecular mechanisms, and impact of diabetes on OC. The effect of different antidiabetic drugs was also discussed in this manuscript. All of the clinical, in vivo, and in vitro studies were included in the present study.

RESULTS

The diagnosis of diabetes mellitus negatively affects the survival and prognosis in OC cases. The epidemiologic data shows that the risk of OC increases in patients with diabetes mellitus compared to the healthy population. Insulin-like growth factors family was raised in diabetic patients, which target several mechanisms, including targeting oxidative stress, angiogenesis, and tumor markers. Antidiabetic drugs such as metformin, sitagliptin, and rosiglitazone have a promising effect on elongation of survival and enhancement of prognosis in OC patients.

CONCLUSIONS

Diabetes mellitus is a significant risk factor for OC in women, and it negatively impacts survival and prognosis. Molecular mechanisms such as IGF family, oxidative stress, and inflammatory cytokines have been identified to explain this relationship. Antidiabetic drugs like metformin, sitagliptin, and rosiglitazone have shown promise in improving survival and prognosis of OC patients.

The Association between Diabetes Medication Use and Tumour Characteristics at Diagnosis in Patients with Urothelial Carcinoma: A Retrospective Registry-Based Study1

BACKGROUND: Observational studies indicate a potential association between diabetes medication use and aggressiveness of bladder cancer. OBJECTIVE: The objective is to exploratively study the association between diabetes medication use, as proxy for diabetes, and cancer characteristics of urothelial carcinoma at diagnosis. Furthermore, differences in associations between specific types of diabetes medication are studied. METHODS: The association between use of diabetes medication and urothelial carcinoma (UC) characteristics at diagnosis is studied. A retrospective registry-based study among UC patients in the Netherlands was performed for which two large linked registries from PHARMO and IKNL were used. Patients diagnosed with UC between 2000 and 2016 and no previous cancer were included in this study. UC patients using diabetes medication were matched on age and sex with subjects not using diabetes medication (ratio 1:2), resulting in 1,164 diabetes medication users and 2,318 non-users. Conditional logistic regression analysis was performed to determine odds ratios comparing cancer characteristics between different types of diabetes medication users to non-users. RESULTS: Noninsulin antidiabetic drugs (NIAD) use was associated with a muscle-invasive type of UC compared to non-users (OR = 1.31, 95% CI: 1.10–1.55 for T2+ versus Ta) as well as a poorly differentiated tumour (OR = 1.31, 95% CI: 1.07–1.59 for poorly versus well differentiated tumours). CONCLUSION: Users of diabetes medication are potentially more likely to be diagnosed with a more aggressive tumour than non-users; however, lifestyle factors could not be adjusted for.

Systematic analysis and prediction for disease burden of ovarian cancer attributable to hyperglycemia: a comparative study between China and the world from 1990 to 2019

Background

Ovarian cancer is one of the most common female malignancies worldwide, and metabolic factors, such as hyperglycemia, are becoming potential risk factors. This study aimed to analyze the disease burden and its changing trend of ovarian cancer attributable to hyperglycemia in the Chinese population from 1990 to 2019.

Methods

Using the data released by the Global Burden of Disease study 2019 (GBD 2019), we analyze the disease burden of ovarian cancer attributable to hyperglycemia in Chinese from 1990 to 2019 via morbidity, death, disability-adjusted life years (DALY); compare it with the global population; and predict the incidence and death trend in Chinese women for the next 10 years (2020-2029).

Results

The incidence, death cases, and DALY numbers of ovarian cancer attributable to hyperglycemia in Chinese in 2019 were 2,751, 1,758, and 44,615 person-years, respectively, with an increase of 352.5%, 356.6%, and 329.0% compared with 1990, and the growth rate was higher than the global level. The age-standardized incidence rate (ASIR), age-standardized mortality rate (ASMR), and age-standardized DALY rate (ASDR) in 2019 were 0.270/100,000, 0.164/100,000, and 4.103/100,000, respectively. Moreover, the average annual percent changes (AAPCs) were 2.3%, 2.0%, and 2.0%, respectively, all higher than the global average. The disease burden of ovarian cancer attributable to hyperglycemia increased with age, reaching a peak in the 45-75 age group. The prediction of the neural network model showed that the incidence and death of the disease would remain high and rise in the next 10 years.

Conclusion

The disease burden caused by ovarian cancer attributable to hyperglycemia in Chinese accounts for a large proportion globally, and the ASIR, ASMR, and ASDR are increasing year by year. We should continue to pay attention to the role of metabolic factors, such as hyperglycemia, in the occurrence and development of ovarian cancer, perform a good job in tertiary prevention, and strive to reduce health losses.

Dipeptidyl Peptidase (DPP)-4 Inhibitor Impairs the Outcomes of Patients with Type 2 Diabetes Mellitus After Curative Resection for Colorectal Cancer

Dipeptidyl peptidase IV inhibitor (DPP-4i) has been shown to act either as a promoter or as a suppressor for cancer. Although epidemiologic studies suggest that DPP-4i does not correlate with the development of malignancies, its effects on cancer metastases are controversial. We evaluated the impact of DPP-4i on postoperative outcomes of the diabetic patients with colorectal cancer and microscopic features of the resected tumors. In 260 consecutive patients with type 2 diabetes mellitus (T2DM) who underwent curative resection of colorectal cancer, the correlation between DPP-4i use and prognosis was retrospectively examined. Expression of Zeb1 on tumor cells and density of infiltrating immune cells were quantitatively evaluated with multicolor IHC in 40 tumors from DPP-4i users, 40 tumors from propensity score-matched users, and 40 tumors from nonusers. Postoperative disease-free survival (DFS) was significantly lower in 135 patients treated with DPP-4i compared with 125 nontreated patients [5-year DFS, 73.7% vs. 87.4%; HR, 1.98; 95% confidence interval (CI), 1.05-3.71; P = 0.035]. IHC revealed that the number of Zeb1⁺ tumor cells increased in tumors from DPP-4i-treated patients than tumors from nonusers (P < 0.01). The densities of CD3⁺ and CD8⁺ T cells were significantly lower in tumors from DPP-4i users (P < 0.01) with decreased density of tertiary lymphoid structures (P < 0.001). However, the density of M2-type tumor-associated macrophages with CD68⁺ CD163⁺ phenotypes was significantly higher (P < 0.01) in tumors from DPP-4i users. Exposure of colorectal cancer to DPP-4i may accelerate epithelial-to-mesenchymal transition (EMT) creating a tumor-permissive immune microenvironment, which might impair the outcomes of the patients with colorectal cancer and T2DM.

Significance

DPP-4i has been shown to enhance the antitumor effects of immunotherapy. However, we found that DPP-4i significantly impairs the outcomes of patients with colorectal cancer who underwent curative resection, possibly through acceleration of EMT and creation of a tumor-permissive immune microenvironment. This suggests that DPP-4i must be used with caution until its safety is fully confirmed by further studies of the mechanistic effects on existing cancers in humans.

Disease Burden and Attributable Risk Factors of Ovarian Cancer From 1990 to 2017: Findings From the Global Burden of Disease Study 2017

Aim: We aimed to estimate the disease burden and risk factors attributable to ovarian cancer, and epidemiological trends at global, regional, and national levels.

Methods: We described ovarian cancer data on incidence, mortality, and disability-adjusted life-years as well as age-standardized rates from 1990 to 2017 from the Global Health Data Exchange database. We also estimated the risk factors attributable to ovarian cancer deaths and disability-adjusted life-years. Measures were stratified by region, country, age, and socio-demographic index. The estimated annual percentage changes and age-standardized rates were calculated to evaluate temporal trends.

Results: Globally, ovarian cancer incident, death cases, and disability-adjusted life-years increased by 88.01, 84.20, and 78.00%, respectively. However, all the corresponding age-standardized rates showed downward trends with an estimated annual percentage change of −0.10 (−0.03 to 0.16), −0.33 (−0.38 to −0.27), and −0.38 (−0.32 to 0.25), respectively. South and East Asia and Western Europe carried the heaviest disease burden. The highest incidence, deaths, and disability-adjusted life-years were mainly in people aged 50–69 years from 1990 to 2017. High fasting plasma glucose level was the greatest contributor in age-standardized disability-adjusted life-years rate globally as well as in all socio-demographic index quintiles and most Global Disease Burden regions. Other important factors were high body mass index and occupational exposure to asbestos.

Conclusion: Our study provides valuable information on patterns and trends of disease burden and risk factors attributable to ovarian cancer across age, socio-demographic index, region, and country, which may help improve the rational allocation of health resources as well as inform health policies.

Insulin-like Growth Factor 2 mRNA-Binding Protein 2-a Potential Link Between Type 2 Diabetes Mellitus and Cancer

CONTEXT

Type 2 diabetes mellitus (T2DM) and cancer share a variety of risk factors and pathophysiological features. It is becoming increasingly accepted that the 2 diseases are related, and that T2DM increases the risk of certain malignancies.

OBJECTIVE

This review summarizes recent advancements in the elucidation of functions of insulin-like growth factor 2 (IGF-2) messenger RNA (mRNA)-binding protein 2 (IGF2BP2) in T2DM and cancer.

METHODS

A PubMed review of the literature was conducted, and search terms included IGF2BP2, IMP2, or p62 in combination with cancer or T2DM. Additional sources were identified through manual searches of reference lists. The increased risk of multiple malignancies and cancer-associated mortality in patients with T2DM is believed to be driven by insulin resistance, hyperinsulinemia, hyperglycemia, chronic inflammation, and dysregulation of adipokines and sex hormones. Furthermore, IGF-2 is oncogenic, and its loss-of-function splice variant is protective against T2DM, which highlights the pivotal role of this growth factor in the pathogenesis of these 2 diseases. IGF-2 mRNA-binding proteins, particularly IGF2BP2, are also involved in T2DM and cancer, and single-nucleotide variations (formerly single-nucleotide polymorphisms) of IGF2BP2 are associated with both diseases. Deletion of the IGF2BP2 gene in mice improves their glucose tolerance and insulin sensitivity, and mice with transgenic p62, a splice variant of IGF2BP2, are prone to diet-induced fatty liver disease and hepatocellular carcinoma, suggesting the biological significance of IGF2BP2 in T2DM and cancer.

CONCLUSION

Accumulating evidence has revealed that IGF2BP2 mediates the pathogenesis of T2DM and cancer by regulating glucose metabolism, insulin sensitivity, and tumorigenesis. This review provides insight into the potential involvement of this RNA binding protein in the link between T2DM and cancer.

Cancer and diabetes: the interlinking metabolic pathways and repurposing actions of antidiabetic drugs

Cancers are regarded as one of the main causes of death and result in high health burden worldwide. The management of cancer include chemotherapy, surgery and radiotherapy. The chemotherapy, which involves the use of chemical agents with cytotoxic actions is utilised as a single treatment or combined treatment. However, these managements of cancer such as chemotherapy poses some setbacks such as cytotoxicity on normal cells and the problem of anticancer drug resistance. Therefore, the use of other therapeutic agents such as antidiabetic drugs is one of the alternative interventions used in addressing some of the limitations in the use of anticancer agents. Antidiabetic drugs such as sulfonylureas, biguanides and thiazolidinediones showed beneficial and repurposing actions in the management of cancer, thus, the activities of these drugs against cancer is attributed to some of the metabolic links between the two disorders and these includes hyperglycaemia, hyperinsulinemia, inflammation, and oxidative stress as well as obesity. Furthermore, some studies showed that the use of antidiabetic drugs could serve as risk factors for the development of cancerous cells particularly pancreatic cancer. However, the beneficial role of these chemical agents overweighs their detrimental actions in cancer management. Hence, the present review indicates the metabolic links between cancer and diabetes and the mechanistic actions of antidiabetic drugs in the management of cancers.

Obesity as a Possible Risk Factor for Progression from Monoclonal Gammopathy of Undetermined Significance Progression into Multiple Myeloma: Could Myeloma Be Prevented with Metformin Treatment?

Obesity is increasingly associated with the transformation of monoclonal gammopathy of undetermined significance (MGUS) into multiple myeloma (MM). Obesity, MGUS, and MM share common etiopathogenesis mechanisms including altered insulin axis and the action of inflammatory cytokines. Consistent with this interconnection, metformin could predominantly exert inhibition of these pathophysiological factors and thus be an attractive therapeutic option for MGUS. Despite the possible clinical significance, only a limited number of epidemiological studies have focused on obesity as a risk factor for MGUS and MM. This review describes multiple biological pathways modulated by metformin at the cellular level and their possible impacts on the biology of MGUS and its progression into MM.

Cancer Signaling Transcriptome Is Upregulated in Type 2 Diabetes Mellitus

We aimed to explore the differences in the whole transcriptome of peripheral blood mononuclear cells between elderly individuals with and without type 2 diabetes (T2D). We conducted a microarray-based transcriptome analysis of 19 individuals with T2D and 15 without. Differentially expressed genes according to linear models were submitted to the Ingenuity Pathway Analysis system to conduct a functional enrichment analysis. We established that diseases, biological functions, and canonical signaling pathways were significantly associated with T2D patients when their logarithms of Benjamini–Hochberg-adjusted p-value were >1.30 and their absolute z-scores were >2.0 (≥2.0 meant “upregulation” and ≤ −2.0 “downregulation”). Cancer signaling pathways were the most upregulated ones in T2D (z-score = 2.63, −log(p-value) = 32.3; 88.5% (n = 906) of the total differentially expressed genes located in these pathways). In particular, integrin (z-score = 2.52, −log(p-value) = 2.03) and paxillin (z-score = 2.33, −log(p-value) = 1.46) signaling pathways were predicted to be upregulated, whereas the Rho guanosine diphosphate (Rho-GDP) dissociation inhibitor signaling pathway was predicted to be downregulated in T2D individuals (z-score = −2.14, −log(p-value) = 2.41). Our results suggest that, at transcriptional expression level, elderly individuals with T2D present an increased activation of signaling pathways related to neoplastic processes, T-cell activation and migration, and inflammation.

Metformin changes the immune microenvironment of colorectal cancer in patients with type 2 diabetes mellitus

Accumulating evidence suggests that metformin reduces the incidence and mortality of colorectal cancer (CRC). However, underlying mechanisms have not been fully clarified. The aim of this study was to examine the pathological characteristics of resected CRC from patients treated with metformin for type 2 diabetes mellitus (DM). In total, 267 patients with DM underwent curative colectomy for Stage I‐III CRC and 53 (19.9%) patients had been treated medically including metformin. Pathological N‐stage was significantly lower in metformin‐treated patients (P < .05) with prolonged disease‐free survival (DFS) (P < .05). Immunohistochemistry showed that the densities of CD3(+) and CD8(+) tumor‐infiltrating lymphocytes (TILs) in the invasive front area were significantly higher in 40 patients treated with metformin compared with propensity score matched cases without metformin (P < .05). The density of tertiary lymphoid structures (TLS) in tumor stroma was markedly increased in metformin‐treated patients (P < .001). In those tumors, there were more CD68(+) tumor‐associated macrophages (TAM) infiltrated (P < .05), while the ratio of CD163(+) M2‐phenotype was markedly reduced (P < .001). Stromal fibrosis tended to be suppressed by metformin intake (P = .051). These findings suggested that metformin drastically changes the characteristics of infiltrating immune cells in CRC and reprograms the tumor microenvironment from immunosuppressive to immunocompetent status, which may lead to suppression of microscopic tumor spread and improve the outcomes of patients with CRC and type 2 DM.

No clear associations of adult BMI and diabetes mellitus with non-muscle invasive bladder cancer recurrence and progression

Background

Non-muscle invasive bladder cancer patients are at high risk for tumour recurrence and progression, hence an intensive follow-up procedure is recommended which is costly. Identification of factors that are associated with the risk of recurrence and progression may enable personalized follow-up schedules. Obesity and diabetes mellitus may be associated with a worse prognosis, but the evidence is limited and inconsistent. Our objective was to determine the associations of BMI and diabetes mellitus with risks of recurrence and progression among non-muscle invasive bladder cancer patients.

Methods

A population-based cohort of patients diagnosed with non-muscle invasive bladder cancer between 1995 and 2010 was retrospectively identified from the Netherlands Cancer Registry and invited to participate in the Nijmegen Bladder Cancer Study (n = 1,433). Average weight during adult life, height, and diabetes mellitus diagnosis were self-reported by use of a questionnaire. Clinical follow-up data were retrieved from medical files. Associations were quantified using proportional hazard analyses. For all analyses, minimal adjustment sets were selected using a Directed Acyclic Graph.

Results

Fourteen percent of the patients indicated to be diagnosed with diabetes mellitus, and more than half was overweight (45%) or obese (9%). Compared to healthy weight, overweight and obesity were not associated with risk of recurrence (adjusted hazard ratio (HR) = 1.02; 95% confidence interval (CI): 0.86–1.22, and HR = 1.02; 95% CI: 0.76–1.38, respectively) and overall progression (HR = 1.04; 95% CI: 0.74–1.44, and HR = 1.20; 95% CI: 0.69–2.09, respectively). Also, no clear associations of diabetes mellitus with risk of recurrence (HR = 1.22; 95% CI: 0.98–1.54) and overall progression (HR = 1.16; 95% CI: 0.76–1.76) were found.

Conclusion

Average BMI during adult life and diabetes mellitus were not clearly associated with risk of recurrence or progression in non-muscle invasive bladder cancer. Prospective cohort studies with detailed information on BMI and diabetes mellitus before and after diagnosis are needed to confirm these findings.

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.

Obesity and cancer risk: Emerging biological mechanisms and perspectives

Continuously rising trends in obesity-related malignancies render this disease spectrum a public health priority. Worldwide, the burden of cancer attributable to obesity, expressed as population attributable fraction, is 11.9% in men and 13.1% in women. There is convincing evidence that excess body weight is associated with an increased risk for cancer of at least 13 anatomic sites, including endometrial, esophageal, renal and pancreatic adenocarcinomas; hepatocellular carcinoma; gastric cardia cancer; meningioma; multiple myeloma; colorectal, postmenopausal breast, ovarian, gallbladder and thyroid cancers. We first synopsize current epidemiologic evidence; the obesity paradox in cancer risk and mortality; the role of weight gain and weight loss in the modulation of cancer risk; reliable somatometric indicators for obesity and cancer research; and gender differences in obesity related cancers. We critically summarize emerging biological mechanisms linking obesity to cancer encompassing insulin resistance and abnormalities of the IGF-I system and signaling; sex hormones biosynthesis and pathway; subclinical chronic low-grade inflammation and oxidative stress; alterations in adipokine pathophysiology; factors deriving from ectopic fat deposition; microenvironment and cellular perturbations including vascular perturbations, epithelial-mesenchymal transition, endoplasmic reticulum stress and migrating adipose progenitor cells; disruption of circadian rhythms; dietary nutrients; factors with potential significance such as the altered intestinal microbiome; and mechanic factors in obesity and cancer. Future perspectives regarding prevention, diagnosis and therapeutics are discussed. The aim of this review is to investigate how the interplay of these main potential mechanisms and risk factors, exerts their effects on target tissues provoking them to acquire a cancerous phenotype.

Metformin and blood cancers

Type 2 diabetes mellitus and cancer are correlated with changes in insulin signaling, a pathway that is frequently upregulated in neoplastic tissue but impaired in tissues that are classically targeted by insulin in type 2 diabetes mellitus. Many antidiabetes treatments, particularly metformin, enhance insulin signaling, but this pathway can be inhibited by specific cancer treatments. The modulation of cancer growth by metformin and of insulin sensitivity by anticancer drugs is so common that this phenomenon is being studied in hundreds of clinical trials on cancer. Many meta-analyses have consistently shown a moderate but direct effect of body mass index on the incidence of multiple myeloma and lymphoma and the elevated risk of leukemia in adults. Moreover, new epidemiological and preclinical studies indicate metformin as a therapeutic agent in patients with leukemia, lymphomas, and multiple myeloma. In this article, we review current findings on the anticancer activities of metformin and the underlying mechanisms from preclinical and ongoing studies in hematologic malignancies.

Hyperglycemia promotes insulin-independent ovarian tumor growth

INTRODUCTION

Epithelial ovarian cancer (EOC) is notoriously difficult to diagnose in its earlier and more treatable stages, making it one of the deadliest cancers in women. Comorbid diabetes is associated with poor prognosis in EOC and pro-growth insulin signalling is often considered to be the driving factor. However, EOC cells are also highly glycolytic and insulin-independent glucose uptake is essential to their metabolism. Evidence of gluconeogenesis in cancer in vivo suggests that the normal concentration of circulating glucose does not meet the energy demands of the tumor and may therefore be a limiting factor in cancer cell metabolism. Diabetics have elevated blood glucose that has the potential to meet these energy demands and facilitate cancer progression.

METHODS

To determine whether hyperglycemia is a potentially modifiable factor independent of insulin, orthotopic ovarian tumors were induced in mice with acute Type 1 (hypo-insulinemic) or Type 2 (hyper-insulinemic) diabetes.

RESULTS

Hyperglycemia accelerated the growth of ovarian tumors in a glucose concentration-dependent manner and significantly shortened overall survival. Reciprocally, the presence of a tumor improved impaired glucose tolerance in both Type 1 and Type 2 diabetes. In mice with chronic Type 1 diabetes, hyperglycemia limited tumor growth without changing overall survival, indicating that systemic metabolic stress can accelerate time to death independent of primary tumor size. When modeled in vitro, long-term culture in 25mM vs 6mM glucose resulted in significantly different growth and metabolism.

CONCLUSIONS

Taken together, this study shows that systemic metabolic disturbances can have a profound impact on both the growth of ovarian tumors and on overall survival.

Cancer risks of anti-hyperglycemic drugs for type 2 diabetes treatment - a clinical appraisal

AIM

A clinical appraisal of existing scientific literature sought to assess the need for long-term prospective epidemiological studies to investigate an increased cancer risk of anti-hyperglycemic medication in type 2 diabetes.

METHOD

A focus statement was formulated as: "With a higher risk of cancers in patients with type 2 diabetes, all anti-hyperglycemic drugs should undergo long-term, prospective epidemiological studies for cancer risks." Field surveys were sent to practicing physicians and endocrinologists to identify the currently prevalent level of acceptance of this statement. Subsequently, a meeting with a six-member panel of key opinion leaders was held to discuss published evidence in support and against the statement. This publication reviews the publications and discussion points brought forth in this meeting and their effect on statement acceptance by the panel.

RESULTS

Whereas the majority of field survey responders primarily agreed with the statement, panel members were divided in their statement support. This division remained intact after review of the literature.

CONCLUSIONS

While there was evidence that type 2 diabetes is associated with an increased risk of cancer, existing studies seemed insufficient to definitively demonstrate a link between cancer risk and use of specific anti-hyperglycemic therapies.

Thiazolidinedione drugs in the treatment of type 2 diabetes mellitus: past, present and future

Thiazolidinedione (TZD) drugs used in the treatment of type 2 diabetes mellitus (T2DM) have proven effective in improving insulin sensitivity, hyperglycemia, and lipid metabolism. Though well tolerated by some patients, their mechanism of action as ligands of peroxisome proliferator-activated receptors (PPARs) results in the activation of several pathways in addition to those responsible for glycemic control and lipid homeostasis. These pathways, which include those related to inflammation, bone formation, and cell proliferation, may lead to adverse health outcomes. As treatment with TZDs has been associated with adverse hepatic, cardiovascular, osteological, and carcinogenic events in some studies, the role of TZDs in the treatment of T2DM continues to be debated. At the same time, new therapeutic roles for TZDs are being investigated, with new forms and isoforms currently in the pre-clinical phase for use in the prevention and treatment of some cancers, inflammatory diseases, and other conditions. The aims of this review are to provide an overview of the mechanism(s) of action of TZDs, a review of their safety for use in the treatment of T2DM, and a perspective on their current and future therapeutic roles.

Cancer risk of sulfonylureas in patients with type 2 diabetes mellitus: A systematic review

BACKGROUND

Increasing evidence suggests that oral hypoglycemic agents used in type 2 diabetes mellitus (T2DM) may affect cancer risk. Sulfonylureas (SUs) are the most frequently used antidiabetic medications for T2DM. Whether using SUs has any effect on cancer has received considerable attention. The aim of this study was to assess the effects of SUs on cancer risk in T2DM patients.

METHODS

Published studies were identified in PubMed, EMBASE, and the Cochrane Register of Clinical Studies, and ClinicalTrials.gov was searched for additional information to identify randomized controlled trials (RCTs), cohort studies, and case-control studies. The abstracts and full text were screened, data collected, and the risk of bias assessed for each individual study.

RESULTS

Seventy-seven studies (33 RCTs, 27 cohort studies, and 17 case-control studies) were analyzed. The RCTs did not report a difference in the risk of malignant tumor between SU-treated T2DM patients and controls (odds ratio [OR] 0.96; 95% confidence interval [CI] 0.78-1.18); cohort studies showed that cancer risk was higher in patients using SUs than metformin (relative risk 1.60 [95%CI 1.37-1.87]; adjusted hazard ratio 1.13 [95%CI 1.06-1.19]), and case-control studies suggested a trend for increased cancer risk in those using SUs compared with non-SU users (adjusted OR 1.13; 95%CI 0.93-1.37).

CONCLUSIONS

The available evidence clearly shows that SUs can significantly increase the risk of cancer compared with metformin. Although the evidence suggests the possibility that SU users may have a higher risk of cancer than those using alternative medications in addition to metformin, it remains inadequate to enable definitive conclusions to be drawn.

Obesity-associated digestive cancers: A review of mechanisms and interventions

The prevalence of obesity has steadily increased over the past few decades. Previous studies suggest that obesity is an oncogenic factor and that over 20% of all cancers are obesity-related. Among such cancers, digestive system malignancies (including esophageal adenocarcinomas, colorectal cancers, and cancers of the gastric cardia, liver, and pancreas) are reported most frequently. While the 5-year survival rates of cancers of the breast and prostate are 90%, that rate is only 45% for digestive cancers. In this review, the mechanisms of obesity-associated digestive cancers are discussed, with an emphasis on obesity-related gene mutations, insulin and insulin-like growth factor signaling pathways, chronic inflammation, and altered adipokine levels. Evidence that these factors often function interdependently rather than independently in carcinogenesis is presented. Recommended interventions that may reduce the burden of obesity-associated digestive cancers, such as participation in physical activity, diet modulation, and calorie restriction, are also described.

Every exercise bout matters: linking systemic exercise responses to breast cancer control

Cumulative epidemiological evidence shows that regular exercise lowers the risk of developing breast cancer and decreases the risk of disease recurrence. The causality underlying this relation has not been fully established, and the exercise recommendations for breast cancer patients follow the general physical activity guidelines, prescribing 150 min of exercise per week. Thus, elucidations of the causal mechanisms are important to prescribe and implement the most optimal training regimen in breast cancer prevention and treatment. The prevailing hypothesis on the positive association within exercise oncology has focused on lowering of the basal systemic levels of cancer risk factors with exercise training. However, another rather overlooked systemic exercise response is the marked acute increases in several potential anti-cancer components during each acute exercise bout. Here, we review the evidence of the exercise-mediated changes in systemic components with the ability to influence breast cancer progression. In the first part, we focus on systemic risk factors for breast cancer, i.e., sex hormones, insulin, and inflammatory markers, and their adaptation to long-term training. In the second part, we describe the systemic factors induced acutely during exercise, including catecholamines and myokines. In conclusion, we propose that the transient increases in exercise factors during acute exercise appear to be mediating the positive effect of regular exercise on breast cancer progression.

Imbalanced insulin action in chronic over nutrition: Clinical harm, molecular mechanisms, and a way forward

The growing worldwide prevalence of overnutrition and underexertion threatens the gains that we have made against atherosclerotic cardiovascular disease and other maladies. Chronic overnutrition causes the atherometabolic syndrome, which is a cluster of seemingly unrelated health problems characterized by increased abdominal girth and body-mass index, high fasting and postprandial concentrations of cholesterol- and triglyceride-rich apoB-lipoproteins (C-TRLs), low plasma HDL levels, impaired regulation of plasma glucose concentrations, hypertension, and a significant risk of developing overt type 2 diabetes mellitus (T2DM). In addition, individuals with this syndrome exhibit fatty liver, hypercoagulability, sympathetic overactivity, a gradually rising set-point for body adiposity, a substantially increased risk of atherosclerotic cardiovascular morbidity and mortality, and--crucially--hyperinsulinemia. Many lines of evidence indicate that each component of the atherometabolic syndrome arises, or is worsened by, pathway-selective insulin resistance and responsiveness (SEIRR). Individuals with SEIRR require compensatory hyperinsulinemia to control plasma glucose levels. The result is overdrive of those pathways that remain insulin-responsive, particularly ERK activation and hepatic de-novo lipogenesis (DNL), while carbohydrate regulation deteriorates. The effects are easily summarized: if hyperinsulinemia does something bad in a tissue or organ, that effect remains responsive in the atherometabolic syndrome and T2DM; and if hyperinsulinemia might do something good, that effect becomes resistant. It is a deadly imbalance in insulin action. From the standpoint of human health, it is the worst possible combination of effects. In this review, we discuss the origins of the atherometabolic syndrome in our historically unprecedented environment that only recently has become full of poorly satiating calories and incessant enticements to sit. Data are examined that indicate the magnitude of daily caloric imbalance that causes obesity. We also cover key aspects of healthy, balanced insulin action in liver, endothelium, brain, and elsewhere. Recent insights into the molecular basis and pathophysiologic harm from SEIRR in these organs are discussed. Importantly, a newly discovered oxide transport chain functions as the master regulator of the balance amongst different limbs of the insulin signaling cascade. This oxide transport chain--abbreviated 'NSAPP' after its five major proteins--fails to function properly during chronic overnutrition, resulting in this harmful pattern of SEIRR. We also review the origins of widespread, chronic overnutrition. Despite its apparent complexity, one factor stands out. A sophisticated junk food industry, aided by subsidies from willing governments, has devoted years of careful effort to promote overeating through the creation of a new class of food and drink that is low- or no-cost to the consumer, convenient, savory, calorically dense, yet weakly satiating. It is past time for the rest of us to overcome these foes of good health and solve this man-made epidemic.

A Linear Dose-Response Relationship between Fasting Plasma Glucose and Colorectal Cancer Risk: Systematic Review and Meta-analysis

For many years, the question of whether hyperglycaemia, a manifestation of prediabetes, diabetes mellitus and metabolic syndrome, is a risk factor for colorectal cancer has been intensely studied. In fact, even after the conclusion of several prospective studies, the topic is still controversial. We conducted a systematic review and meta-analysis to investigate the dose-response relationship between blood glucose concentration and the incidence of colorectal cancer. A linear (P = 0.303 for non-linearity) dose-response relationship was observed between fasting plasma glucose (FPG) and colorectal cancer risk without significant heterogeneity. The relative risk (RR) for colorectal cancer per 20 mg/dL increase in FPG was 1.015 (95% CI: 1.012-1.019, P = 0.000). In subgroup analyses, the pooled RRs for colon cancer (CC) and rectal cancer (RC) studies were 1.035 (95% CI 1.008-1.062, P = 0.011) and 1.031 (95% CI: 0.189-5.628, P = 0.972), respectively; in the analysis comparing men and women, the pooled RRs were 1.016 (95% CI: 1.012-1.020, P = 0.000) and 1.011 (95% CI: 0.995-1.027, P = 0.164), respectively. Sensitivity analyses using two methods showed similar results. In conclusion, there is a significant linear dose-response relationship between FPG and the incidence risk of colorectal cancer. For people with diabetes or prediabetes, controlling blood glucose might be useful to prevent colorectal cancer.

Diabetes mellitus and cancer of the digestive organs: An Italian population-based cohort study

AIMS

The association between diabetes mellitus and the occurrence of digestive organs cancers was investigated in the Italian region Friuli Venezia Giulia. The risk of cancer associated with oral antidiabetic drugs among subjects with type 2 diabetes was also assessed.

METHODS

This was a retrospective population-based cohort study based on the 2002-2014 regional administrative health data. Incident digestive cancers were identified through the hospital discharge diagnoses. The incidence rates of cancer at different sites were calculated for type 1 and 2 diabetics and for non-diabetics. Proportional hazard models were built to assess the risk of cancer associated with diabetes and antidiabetic drugs.

RESULTS

Diabetes was associated with increased risk of digestive cancers. Liver and pancreatic cancers were associated with the highest hazard ratios. Among type 2 diabetics, total number of metformin prescriptions was associated with reduced risk of most types of digestive cancers; sulfonylureas with reduced risk of stomach and pancreatic cancer.

CONCLUSIONS

In this Italian population the excess risk of digestive cancers for diabetic patients was confirmed. Further research is needed to clarify the role of antidiabetic drugs.

Repurposing old drugs to chemoprevention: the case of metformin

Multiple epidemiologic studies have documented an association between the anti-diabetic agent metformin and reduced cancer incidence and mortality. However, this effect has not been consistently demonstrated in animal models or more recent epidemiological studies. The purpose of this paper is to examine metformin's chemopreventive potential by reviewing relevant mechanisms of action, preclinical evidence of efficacy, updated epidemiologic evidence after correction for potential biases and confounders, and recently completed and ongoing clinical trials. Although repurposing drugs with well described mechanisms of action and safety profiles is an appealing strategy for cancer prevention, there is no substitute for well executed late phase clinical trials to define efficacy and populations that are most likely to benefit from an intervention.

Glycemic Variation in Tumor Patients with Total Parenteral Nutrition

Background:

Hyperglycemia is associated with poor clinical outcomes and mortality in several patients. However, studies evaluating hyperglycemia variation in tumor patients receiving total parenteral nutrition (TPN) are scarce. The aim of this study was to assess the relationship between glycemia and tumor kinds with TPN by monitoring glycemic variation in tumor patients.

Methods:

This retrospective clinical trial selected 312 patients with various cancer types, whose unique nutrition treatment was TPN during the monitoring period. All patients had blood glucose (BG) values assessed at least six times daily during the TPN infusion. The glycemic variation before and after TPN was set as the indicator to evaluate the factors influencing BG.

Results:

The clinical trial lasted 7.5 ± 3.0 days adjusted for age, gender, family cancer history and blood types. There were six cancer types: Hepatic carcinoma (HC, 21.8%), rectal carcinoma (17.3%), colon carcinoma (CC, 14.7%), gastric carcinoma (29.8%), pancreatic carcinoma (11.5%), and duodenal carcinoma (DC, 4.8%). The patients were divided into diabetes and nondiabetes groups. No statistical differences in TPN glucose content between diabetes and nondiabetes groups were found; however, the tumor types affected by BG values were obvious. With increasing BG values, DC, HC and CC were more represented than other tumor types in this sequence in diabetic individuals, as well as in the nondiabetic group. BG was inclined to be more easily influenced in the nondiabetes group. Other factors did not impact BG values, including gender, body mass index, and TPN infusion duration time.

Conclusions:

When tumor patients are treated with TPN, BG levels should be monitored according to different types of tumors, besides differentiating diabetes or nondiabetes patients. Special BG control is needed for DC, HC and CC in both diabetic and nondiabetic patients. If BG overtly increases, positive measurements are needed to control BG values. The ClinicalTrials.gov ID is NCT02024321.

Type 2 Diabetes and Breast Cancer: The Interplay between Impaired Glucose Metabolism and Oxidant Stress

Metabolic disorders, especially type 2 diabetes and its associated complications, represent a growing public health problem. Epidemiological findings indicate a close relationship between diabetes and many types of cancer (including breast cancer risk), which regards not only the dysmetabolic condition, but also its underlying risk factors and therapeutic interventions. This review discusses the advances in understanding of the mechanisms linking metabolic disorders and breast cancer. Among the proposed mechanisms to explain such an association, a major role is played by the dysregulated glucose metabolism, which concurs with a chronic proinflammatory condition and an associated oxidative stress to promote tumour initiation and progression. As regards the altered glucose metabolism, hyperinsulinaemia, both endogenous due to insulin-resistance and drug-induced, appears to promote tumour cell growth through the involvement of innate immune activation, platelet activation, increased reactive oxygen species, exposure to protumorigenic and proangiogenic cytokines, and increased substrate availability to neoplastic cells. In this context, understanding the relationship between metabolic disorders and cancer is becoming imperative, and an accurate analysis of these associations could be used to identify biomarkers able to predict disease risk and/or prognosis and to help in the choice of proper evidence-based diagnostic and therapeutic protocols.

Pharmacological activation of PPAR gamma ameliorates vascular endothelial insulin resistance via a non-canonical PPAR gamma-dependent nuclear factor-kappa B trans-repression pathway

Vascular endothelial insulin resistance (IR) is a critically initial factor in cardiocerebrovascular events resulted from diabetes and is becoming a worldwide public health issue. Thiazolidinediones (TZDs) are clinical insulin-sensitizers acting through a canonical peroxisome proliferator-activated receptor gamma (PPARγ)-dependent insulin trans-activation pathway. However, it remains elusive whether there are other mechanisms. In current study, we investigated whether TZDs improve endothelial IR induced by high glucose concentration or hyperglycemia via a non-canonical PPARγ-dependent nuclear factor-kappa B (NF-κB) trans-repression pathway. Our results showed that pre-treatment with TZDs dramatically decrease the susceptibility of endothelial cell to IR, while post-treatment notably improve the endothelial IR both in vitro and in vivo. Moreover, TZDs substantially increase the levels of endothelial nitric oxide synthase (eNOS) and inhibitory κB alpha (IκBα), whereas decrease those of the phosphorylated inhibitory κB kinase alpha/beta (phosphor-IKKα/β) and the cytokines including tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cellular adhesion molecule-1 (sVCAM-1), suggesting that TZDs act indeed through a PPARγ-dependent NF-κB trans-repression pathway. These findings highlighted a non-canonical mechanism for TZDs to ameliorate endothelial IR which might provide a potential strategy to prevent and treat the diabetic vascular complications clinically.

Metformin inhibits the proliferation of A431 cells by modulating the PI3K/Akt signaling pathway

The ability of metformin, an antidiabetic drug with wide applications, to inhibit tumor cell growth has recently been discovered. The PI3K/Akt signaling pathway has been found to play an important role in the survival, proliferation and apoptosis of tumor cells. The aim of the present study was to explore the effect of metformin on the proliferation of A431 human squamous cell carcinoma cells and the underlying molecular mechanisms. A431 cells in the logarithmic growth phase were treated with 0, 15, 30, 45 and 60 mM metformin for 12, 24 and 36 h, respectively. Cell morphology with 45 mM metformin treatment for 24 h was observed under a microscope. The proliferation of A431 cells was detected by the Cell Counting kit-8 colorimetric method. The mRNA expression levels of PI3K and Akt were detected by reverse transcription-polymerase chain reaction (RT-PCR). The protein expression levels of PI3K, Akt and phosphorylated (p)-Akt were detected by western blot analysis. Metformin treatment caused morphological change in A431 cells and inhibited their proliferation in a significant time- and dose-dependent manner. RT-PCR results showed that the mRNA expression of PI3K was inhibited by metformin in a time- and dose-dependent manner (P<0.05). However, there was no significant change in the mRNA expression of Akt following metformin treatment (P>0.05). Western blotting results showed that the protein expression levels of PI3K and p-Akt were inhibited by metformin in a time- and dose-dependent manner (P<0.05). In conclusion, metformin significantly inhibited the proliferation of A431 cells in the current study, which may be strongly associated with the inhibition of the PI3K/Akt signaling pathway.

Diabetes and Hepatitis C: A Two-Way Association

Diabetes and hepatitis C infection are both prevalent diseases worldwide, and are associated with increased morbidity and mortality. Most studies, but not all, have shown that patients with chronic hepatitis C are more prone to develop type 2 diabetes (T2D) compared to healthy controls, as well as when compared to patients with other liver diseases, including hepatitis B. Furthermore, epidemiological studies have revealed that patients with T2D may also be at higher risk for worse outcomes of their hepatitis C infection, including reduced rate of sustained virological response, progression to fibrosis and cirrhosis, and higher risk for development of hepatocellular carcinoma. Moreover, hepatitis C infection and mainly its treatment, interferon α, can trigger the development of type 1 diabetes. In this review, we discuss the existing data on this two-way association between diabetes and hepatitis C infection with emphasis on possible mechanisms. It remains to be determined whether the new curative therapies for chronic hepatitis C will improve outcomes in diabetic hepatitis C patients, and conversely whether treatment with Metformin will reduce complications from hepatitis C virus infection. We propose an algorithm for diabetes screening and follow-up in hepatitis C patients.

Obesity and cancer: at the crossroads of cellular metabolism and proliferation

Obesity is associated with an increased risk of cancer. The mechanisms underlying this association include but are not limited to increased systemic inflammation, an anabolic hormonal milieu, and adipocyte-cancer crosstalk, aberrant stimuli that conspire to promote neoplastic transformation. Cellular proliferation is uncoupled from nutrient availability in malignant cells, promoting tumor progression. Elucidation of the mechanisms underlying the obesity-cancer connection will lead to the development of novel metabolism-based agents for cancer prevention and treatment.

All in the family: Clueing into the link between metabolic syndrome and hematologic malignancies

Metabolic syndrome constitutes a constellation of findings including central obesity, insulin resistance/type 2 diabetes mellitus (DM), dyslipidemia and hypertension. Metabolic syndrome affects 1 in 4 adults in the United States and is rapidly rising in prevalence, largely driven by the dramatic rise in obesity and insulin resistance/DM. Being central to the development of metabolic syndrome and its other related diseases, much focus has been placed on identifying the mitogenic effects of obesity and insulin resistance/DM as mechanistic clues of the link between metabolic syndrome and cancer. Pertinent mechanisms identified include altered lipid signaling, adipokine and inflammatory cytokine effects, and activation of PI3K/Akt/mTOR and RAS/RAF/MAPK/ERK pathways via dysregulated insulin/insulin-like growth factor-1 (IGF-1) signaling. Through variable activation of these multiple pathways, obesity and insulin resistance/DM pre-dispose to hematologic malignancies, imposing the aggressive and chemo-resistant phenotypes typically seen in cancer patients with underlying metabolic syndrome. Growing understanding of these pathways has identified druggable cancer targets, rationalizing the development and testing of agents like PI3K inhibitor idelalisib, mTOR inhibitors everolimus and temsirolimus, and IGF-1 receptor inhibitor linsitinib. It has also led to exploration of obesity and diabetes-directed therapies including statins and oral hypoglycemic for the management of metabolic syndrome-related hematologic neoplasms.

Obesity and cancer--mechanisms underlying tumour progression and recurrence

Over the past several years, the field of cancer research has directed increased interest towards subsets of obesity-associated tumours, which include mammary, renal, oesophageal, gastrointestinal and reproductive cancers in both men and women. The increased risk of breast cancer that is associated with obesity has been widely reported; this has drawn much attention and as such, warrants investigation of the key mechanisms that link the obese state with cancer aetiology. For instance, the obese setting provides a unique adipose tissue microenvironment with concomitant systemic endocrine alterations that favour both tumour initiation and progression. Major metabolic differences exist within tumours that distinguish them from non-transformed healthy tissues. Importantly, considerable metabolic differences are induced by tumour cells in the stromal vascular fraction that surrounds them. The precise mechanisms that underlie the association of obesity with cancer and the accompanying metabolic changes that occur in the surrounding microenvironment remain elusive. Nonetheless, specific therapeutic agents designed for patients with obesity who develop tumours are clearly needed. This Review discusses recent advances in understanding the contributions of obesity to cancer and their implications for tumour treatment.

Obesity and cancer pathogenesis

Overweight and obesity have reached pandemic levels on a worldwide basis and are associated with increased risk and worse prognosis for many but not all malignancies. Pathophysiologic processes that affect this association are reviewed, with a focus on the relationship between type 2 diabetes mellitus and cancer, lessons learned from the use of murine models to study the association, the impact of obesity on pancreatic cancer, the effects of dietary fats and cholesterol on cancer promotion, and the mechanisms by which the intestinal microbiome affects obesity and cancer.

Colorectal cancer: Histopathologic differences in tumor characteristics between patients with and without diabetes

BACKGROUND

Current literature suggests that diabetes is a possible predictor of risk and worse outcome in colorectal cancer (CRC). The objective of this study was to explore if there are histopathologic differences in CRC between populations with and without diabetes.

PATIENTS AND METHODS

Retrospective analysis was done on 534 patients with CRC. Patients were divided into diabetic and nondiabetic subgroups. Data were collected for lymphovascular invasion, tumor location, depth invasion, staging, level of differentiation, histologic type, and presence of tumor components (mucinous, signet ring, or neuroendocrine).

RESULTS

Univariately, patients with diabetes had deeper tumor invasion, greater lymphovascular invasion, and higher TNM staging (OR and 95% CI, 2.06 [1.37, 3.10], 2.52 [1.74, 3.63], and 2.45 [1.70, 3.52], respectively; P < .001). Covariate adjustment retained the significant effect of diabetes on tumor characteristics (P < .005). Multivariable adjustment significantly linked diabetes with signet ring cell carcinoma (log odds, 11.40 ± 5.28; P = .03) and tumor components (log odds, 0.58 ± 0.25; P = .02). Patients with diabetes with hyperlipidemia had more well-differentiated tumors (log odds, -0.96 ± 0.47; P = .04). Transverse tumors were more common in patients with diabetes (log odds, 1.74 ± 0.72; P = .02).

CONCLUSION

Patients with diabetes had worse histopathologic CRC features. Hyperinsulinemia, insulinlike growth factor receptor activation, and hyperglycemia in diabetes can activate mitogenic pathways stimulating proliferation, invasion, angiogenesis, and metastasis. Future research is needed to identify responsible pathways for targeted therapy and to examine the role of better glycemic control and treatment in patients with CRC and diabetes.