Cancer and diabetes: are we ready for prime time?

Insulin Resistance: The Increased Risk of Cancers

Insulin resistance, also known as impaired insulin sensitivity, is the result of a decreased reaction of insulin signaling to blood glucose levels. This state is observed when muscle cells, adipose tissue, and liver cells, improperly respond to a particular concentration of insulin. Insulin resistance and related increased plasma insulin levels (hyperinsulinemia) may cause metabolic impairments, which are pathological states observed in obesity and type 2 diabetes mellitus. Observations of cancer patients confirm that hyperinsulinemia is a major factor influencing obesity, type 2 diabetes, and cancer. Obesity and diabetes have been reported as risks of the initiation, progression, and metastasis of several cancers. However, both of the aforementioned pathologies may independently and additionally increase the cancer risk. The state of metabolic disorders observed in cancer patients is associated with poor outcomes of cancer treatment. For example, patients suffering from metabolic disorders have higher cancer recurrence rates and their overall survival is reduced. In these associations between insulin resistance and cancer risk, an overview of the various pathogenic mechanisms that play a role in the development of cancer is discussed.

Advanced nano-therapeutic delivery of metformin: potential anti-cancer effect against human colon cancer cells through inhibition of GPR75 expression

The high incidence rate coupled with significant mortality makes colorectal cancer one of the most prevalent and devastating cancers worldwide. Research is currently underway to explore new forms of treatment that could potentially maximize treatment outcomes while minimizing the side effects associated with conventional chemotherapy. Metformin, a natural biguanide drug, has anti-cancer properties that can inhibit the growth and proliferation of cancer cells. However, due to its short half-life and low bioavailability, the efficacy of Metf as an anti-cancer agent is limited. The purpose of this research is to assess the potency of PEGylated niosomes as a nano-delivery system for Metf, with the aim of increasing its anti-cancer effects on CaCo2 colorectal cancer cells through the effect on the expression of genes, including GPR75, hTERT, Bax, Bcl2, and Cyclin D1. Metf-loaded niosomal NPs (N-Metf) were synthesized using the thin-film hydration method and then characterized using SEM, FTIR, AFM, and DLS techniques. The release pattern of the drug from the nanoparticles (NPS) was determined using the dialysis membrane method. Furthermore, the cytotoxic effect of the metformin-loaded PEGylated niosome on the CaCo2 cell line was evaluated by the MTT test. Additionally, an apoptosis assay was conducted to assess the effect of free Metf and Metf-loaded NPS on the programmed death of the CaCo2 cells, and the impact on the cell cycle was studied through a cell cycle test. Finally, the expression levels of hTERT, Cyclin D1, BCL2, GPR75, and BAX genes were assessed in the presence of free Metf and Metf-loaded NPs by RT-PCR. Characterization experiments showed successful loading of metformin into PEGylated niosomes. The results of cytotoxicity evaluation showed that Metf-NPs had more cytotoxicity than free Metf in a dose-dependent manner. Furthermore, nuclear fragmentation and the percentage of apoptotic cells induced by Metf-NPs were significantly higher than those induced by free Metf. Additionally, Metf-NPs were found to induce more cell cycle arrest at the sub-G1 checkpoint than free Metf did. Compared with Metf-treated cells, the mRNA expression levels of GPR75, Cyclin D1, and hTERT were significantly changed in cells treated with Metf-NPs. Ultimately, it is hypothesized the nano-encapsulation of Metf into PEGylated niosomal NPs could be a worthwhile drug delivery system to enhance its effectiveness in treating colorectal cancer cells.

Metformin resistant MDA-MB-468 cells exhibit EMT-like phenotype and increased migration capacity

PURPOSE

Metformin is one of the most prescribed drugs for the treatment of type II diabetes. Its anti-proliferative effect is also taken advantage for the treatment of cancer. Despite many of the studies mentioning the positive effects of metformin in inhibiting the proliferation of cancer cells, there are also studies which questions this idea as well.

METHODS

In this study, we investigated the most widely studied breast cancer cell lines, ER (+) MCF7 cells, TNBC MDA-MB-231 and MDA-MB-468 cells in terms of metastatic behavior under long-term metformin treatment. MCF7, MDA-MB-231 and MDA-MB-468 cells were gained resistant to metformin starting from 0.2 to 3.2 mM.

RESULTS

Compared to MCF7 and MDA-MB-231 cell lines, we only observed dramatic changes in MDA-MB-468 cells whose morphology has been changed towards mesenchymal like phenotype. Moreover, migration capacity of these cells was also significantly increased which were validated at both mRNA and protein levels as well as wound healing assay. In addition to EMT like phenotype and increasing migration capacity of metformin resistant MDA-MB-468 cells, they exhibited less sensitivity to PI3K inhibitor.

CONCLUSIONS

All together, our data pointed out that, metformin's effects should be questioned depending on the subtype of the breast cancer that's to be treated.

Cross talk between COVID-19 and breast cancer

Cancer patients are more susceptible for COVID-19; however, the prevalence of COVID-19 in different types of cancer is still inconsistent and inconclusive. Here, we delineate the intricate relationship between breast cancer and COVID-19. Breast cancer and COVID-19 share involvement of common comorbidities, hormonal signalling pathways, gender differences, rennin-angiotensin system (RAS), angiotensin-converting enzyme-2 (ACE-2), transmembrane protease serine 2 (TMPRSS2) and dipeptidyl peptidase-IV (DPP-IV). We also shed light on the possible effects of therapeutic modalities of COVID-19 on breast cancer outcomes. Briefly, we conclude that breast cancer patients are more susceptible for COVID-19 in comparison with their normal counterparts. Women are more resistant for the occurrence and severity of COVID-19. Increased expression of ACE2 and TMPRSS2 are being correlated with occurrence and severity of COVID-19, but higher expression of ACE2 and lower expression of TMPRSS2 are prognostic markers for overall and disease free survival in breast cancer. The ACE2 inhibitors and ibuprofen therapies for COVID-19 treatment may aggravate the clinical condition of the breast cancer patients through chemo-resistance and metastasis. Most of the available therapeutic modalities for COVID-19 were also found to exert positive effects on breast cancer outcomes. Besides drugs in clinical trend, TMPRSS2 inhibitors, estrogen supplementation, androgen deprivation and DPP-IV inhibitors may also be used to treat breast cancer patients infected with SARS-CoV-2. However, drug-drug interactions suggest that some of the drugs used for the treatment of COVID-19 may modulate the drug metabolism of anticancer therapies which may leads to adverse drug reaction events.

Role of metformin in various pathologies: state-of-the-art microcapsules for improving its pharmacokinetics

Metformin was originally derived from a botanical ancestry and became the most prescribed, first-line therapy for Type 2 diabetes in most countries. In the last century, metformin was discovered twice for its antiglycemic properties in addition to its antimalarial and anti-influenza effects. Metformin exhibits flip-flop pharmacokinetics with limited oral bioavailability. This review outlines metformin pharmacokinetics, pharmacodynamics and recent advances in polymeric particulate delivery systems as a potential tool to target metformin delivery to specific tissues/organs. This interesting biguanide is being rediscovered this century for multiple clinical indications as anticancer, anti-aging, anti-inflammatory, anti-Alzheimer's and much more. Microparticulate delivery systems of metformin may improve its oral bioavailability and optimize the therapeutic goals expected.

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.

Novel Metformin-Based Schiff Bases: Synthesis, Characterization, and Antibacterial Evaluation

Novel Schiff bases of metformin hydrochloride and (ortho)para-nitrobenzaldehyde were synthesized by employing two efficient environmentally friendly methods, namely, stirring and microwave-assisted methods using water as the solvent. The advantage of microwave irradiation over the other methods was represented in the reduction of reaction time and wastes, and good yields; however, water in both methods plays the role of eco-friendly solvent. The structural properties of the (ortho)para-isomer products were analyzed by elemental analysis, Fourier transform infrared (FTIR) spectroscopy, UV-Visible (UV-Vis) spectroscopy, ¹H nuclear magnetic resonance (NMR) spectroscopy, ¹³C NMR spectroscopy, mass spectroscopy, and differential scanning calorimetry (DSC). The newly synthesized compounds were screened for their antibacterial activity against selected Gram-positive (ATCC 25923, ATCC 43300, and ATCC 29212) and Gram-negative (ATCC 25922, ATCC 27853, and ATCC 700603) bacteria using the agar well diffusion method. Compared with the standard drug streptomycin, both Schiff bases exhibited moderate bactericidal activity against the tested bacteria with higher values of ortho-nitro compared with the para-nitro isomer; however, no effect on ATCC 43300 and ATCC 27853 was observed under the experimental conditions employed.

Global Versus Indian Perspective of Pioglitazone-induced Adverse Drug Reactions Including Bladder Cancer: A Comparative Retrospective Pharmacovigilance Analysis

PURPOSE

In 2011, France and Germany banned pioglitazone due to a concomitant risk for bladder cancer. There has been continued debate about this topic. Therefore, we present a detailed analysis of data from individual case safety reports of pioglitazone use (PG-ICSRs) associated with bladder cancer reported worldwide and in India.

METHODS

Data from PG-ICSRs reported by the National Coordination Centre's Pharmacovigilance Programme of India, as well as over 131 World Health Organization member countries in the Uppsala Monitoring Centre's VigiLyze pharmacovigilance database system, from January 1, 1967, to March 4, 2018, were collected. Comparisons between data from global and Indian PG-ICSRs were made by applying filters such as country, bladder cancer, age group, gender, time period, information component, and data mining.

FINDINGS

Among the adverse drug reactions (ADRs) reported with pioglitazone use worldwide, bladder cancer and related terms were the most highly reported (43%). The most frequently co-reported concurrently used drug was metformin, which was included in 25% and 40% of overall and bladder cancer-specific PG-ICSRs, respectively. Suspected bladder cancer-specific pioglitazone-related reactions were reported in 27 countries, with 8548 serious and 1858 fatal cases and an information components value of 9.15. The Americas had the highest relative percentage of suspected bladder cancer in PG-ICSRs (53%), while the prevalence was much lower in India (2%). In both cohorts, men over the age of 45 years constituted the most highly reported population.

IMPLICATIONS

India has a very low prevalence of reported overall and bladder cancer-specific pioglitazone-related ADRs compared to Europe and the Americas. Possible explanations for the difference in reporting rates include variance in genetic makeup, low BC risk factor, pioglitazone prescription at a lower therapeutic dose, greater use of chemopreventive spices in the diet, higher frequency of metformin as a concurrent drug, and under-reporting of ADRs.

Metformin Associated With Increased Survival in Type 2 Diabetes Patients With Pancreatic Cancer and Lymphoma

BACKGROUND

The biguanide drug metformin is one of the most commonly used medications for the treatment of type 2 diabetes mellitus. Diabetics are at an increased risk for cancer. Previous studies have demonstrated improved outcomes in patients taking metformin suffering from prostate, colon, lung, thyroid, and esophageal cancers. Metformin's main antineoplastic mechanism of action is thought to be mediated through inhibition of mammalian target of rapamycin, inhibition of hypoxia-inducible factor 1 (HIF-1) alpha, and activation of p53. We investigated the overall survival of type 2 diabetic patients on metformin with pancreatic cancer and lymphoma using the Computerized Patient Record System at the Veterans Affairs Medical Center, Memphis TN.

METHODS

Lymphoma and pancreatic cancer patients with type 2 diabetes were sorted into an experimental (metformin) group and a control (nonmetformin) group. Patients were compared on baseline characteristics including race, body mass index, and age. Cancer outcomes including overall survival, metastasis, recurrences, and incidence of new malignancies were recorded. Hemoglobin A1C, creatinine and cancer treatment modalities were recorded and compared. Statistical analyses used included unpaired t tests and Chi-squared tests.

RESULTS

There was significantly greater overall long-term survival in the metformin group compared to the nonmetformin group for lymphoma (5.89 vs 1.29 years, P < 0.001) and for pancreatic cancer (0.68 vs 0.22 years, P = 0.016). Cancer treatment modalities in both groups were comparable.

CONCLUSIONS

Metformin is associated with a significant, positive effect of increased overall survival in type 2 diabetes patients with pancreatic cancer and lymphoma. These results are encouraging, and prospective studies should be done to further investigate metformin's effects in cancer.

Virtual screening of novel compounds as potential ER-alpha inhibitors

Majority of breast cancers diagnosed today are estrogen receptor (ER)-positive, however, progesterone receptor-positive (PR-positive) is also responsible for breast cancer. Tumors that are ER/PR-positive are much more likely to respond to hormone therapy than tumors that are ER/PR-negative. Nearly 105 ERa inhibitors from literature when docked resulted in 31 compounds (pyrazolo[1,5-a]pyrimidine analogs and chromen-2-one derivatives) with better binding affinities. The maximum score obtained was -175.282 kcal/mol for compound, [2-(4- Fluoro-phenylamino)-pyridin-3-yl]-{4-[2-phenyl-7- (3, 4, 5-trimethoxy-phenyl)-pyrazolo[1,5-a]pyrimidine-5-carbonyl]-piperazin-1-yl}-methanone. The major H-bond interactions are observed with Thr347. In pursuit to identify novel ERa inhibitory ligands, virtual screening was carried out by docking pyrazole, bipyrazole, thiazole, thiadiazole etc scaffold analogs from literature.34 bipyrazoles from literature revealed Compound 2, ethyl 5-amino-1-(5-amino-3-anilino-4-ethoxycarbonyl-pyrazol-1-yl)-3-anilino-pyrazole-4-carboxylate, with -175.9 kcal/mol binding affinity with the receptor, where a favourable H-bond was formed with Thr347.On the other hand, screening 2035 FDA approved drugs from Drug Bank database resulted in 11 drugs which showed better binding affinities than ERa bound tamoxifen. Consensus scoring using 5 scoring schemes such as Mol Dock score, mcule, SwissDock, Pose&Rank and DSX respectively resulted in better rank-sumsfor Lomitapide, Itraconazole, Cobicistat, Azilsartanmedoxomil, and Zafirlukast.

Association of antidiabetic medication and statins with breast cancer incidence in women with type 2 diabetes

Purpose

To address the possible association between the use of metformin, other forms of antidiabetic medication (ADM) and statins with the incidence of breast cancer in women with type 2 diabetes (T2D).

Methods

Data were collected from a Finnish nationwide diabetes database (FinDM). The study cohort consisted of women diagnosed with T2D in 1996–2011 in Finland. In full-cohort analysis, Poisson regression was used to estimate hazard ratios (HRs) in relation to use of metformin, insulin, other forms of oral ADM and statins. In nested case–control analysis, up to 20 controls were matched for age and duration of diabetes to each case of breast cancer. Conditional logistic regression was used to estimate HRs in relation to medication use and cumulative use of different forms of ADM, and statins.

Results

2300 women were diagnosed with breast cancer during follow-up. No difference in breast cancer incidence was observed between metformin users [HR 1.02, 95% confidence interval (CI) 0.93–1.11] or statin users (HR 0.97, 95% CI 0.89–1.05) compared with non-users. In nested case–control analysis the results were similar. Use of insulin (HR 1.18, 95% CI 1.03–1.36) was associated with a slightly increased incidence of breast cancer.

Conclusions

No evidence of an association between the use of metformin or statins and the incidence of breast cancer in women with T2D was found. Among insulin users, a slightly higher incidence of breast cancer was observed.

Electronic supplementary material

The online version of this article (10.1007/s10549-019-05185-0) contains supplementary material, which is available to authorized users.

Association between metabolic syndrome and hepatobiliary cancers: A case-control study

BACKGROUND

The incidence of hepatobiliary cancer is steadily increasing. It is unclear if this rise is related to increasing trends in obesity, metabolic syndrome, and lifestyle changes.

METHODS

A case-control study was performed using the Health Improvement Network (THIN) database. Cases with a diagnosis of liver, bile duct, and gallbladder cancers were matched in a 1:2 fashion with controls and analyzed for potential associations between hepatobiliary cancer and obesity/metabolic syndrome.

RESULTS

Four thousand two hundred and eighty-seven patients (62% male, 38% female) with hepatobiliary cancers were matched with 8574 controls. On univariate analysis, body mass index (BMI), smoking, diabetes, alcohol consumption, ischemic heart disease, and hypertension were associated with hepatobiliary cancer. Statin use and non-smoking status had an inverse association. On multivariate analysis, BMI, diabetes, hypertension, ischemic heart disease, and insulin use were associated with the risk of hepatobiliary cancer. Statin use and non-smoking status were protective. On modeling BMI, each of diabetes and hypertension as a single covariate, there was a significant association with hepatobiliary cancer (1.59 [1.49-1.69], p < 0.001) which persisted despite adjusting for increasing age (1.006 [1005-1.006], p < 0.001) and background liver cirrhosis (1.037 [1.03-1.044], p < 0.001).

CONCLUSIONS

Obesity and metabolic syndrome are associated with the risk of hepatobiliary cancer. Statin use seems to be protective.

Challenges and perspectives in the treatment of diabetes associated breast cancer

Type 2 diabetes mellitus is one of the most common chronic disease worldwide and affects all cross-sections of the society including children, women, youth and adults. Scientific evidence has linked diabetes to higher incidence, accelerated progression and increased aggressiveness of different cancers. Among the different forms of cancer, research has reinforced a link between diabetes and the risk of breast cancer. Some studies have specifically linked diabetes to the highly aggressive, triple negative breast cancers (TNBCs) which do not respond to conventional hormonal/HER2 targeted interventions, have chances of early recurrence, metastasize, tend to be more invasive in nature and develop drug resistance. Commonly used anti-diabetic drugs, such as metformin, have recently gained importance in the treatment of breast cancer due to their proposed anti-cancer properties. Here we discuss the link between diabetes and breast cancer, the metabolic disturbances in diabetes that support the development of breast cancer, the challenges involved and future perspective and directions. We link the three main metabolic disturbances (dyslipidemia, hyperinsulinemia and hyperglycemia) that occur in diabetes to potential aberrant molecular pathways that may lead to the development of an oncogenic phenotype of the breast tissue, thereby leading to acceleration of cell growth, proliferation, migration, inflammation, angiogenesis, EMT and metastasis and inhibition of apoptosis in breast cancer cells. Furthermore, managing diabetes and treating cancer using a combination of anti-diabetic and classical anti-cancer drugs should prove to be more efficient in the treatment diabetes associated cancers.

Early enteral nutrition and total parenteral nutrition on the nutritional status and blood glucose in patients with gastric cancer complicated with diabetes mellitus after radical gastrectomy

Effects of early enteral nutrition (EEN) or total parenteral nutrition (TPN) support on nutritional status and blood glucose in patients with gastric cancer complicated with diabetes mellitus after radical gastrectomy were investigated. One hundred and twenty-nine patients with gastric cancer complicated with diabetes mellitus type 2 admitted to the First People's Hospital of Jinan (Jinan, China), from June 2012 to June 2016 were selected into the study. According to different nutrition support pathways, these patients were randomly divided into the EEN group and the TPN group. The improvement of nutritional indexes, postoperative complications, gastrointestinal function recovery and perioperative blood glucose fluctuation were compared between the two groups. On the 4th day after operation, the improvement levels of total bilirubin (TBL), alanine aminotransferase (ALT), aspartate transaminase (AST), total protein (TP), prealbumin (PAB), hemoglobin (HGB) and weight (Wt) in the EEN group were significantly higher than those in the conventional group (P<0.05). There were no significant differences between the two groups on the 8th day after operation (P>0.05). No patients had complications in the EEN group, while a total of 29 patients in the TPN group suffered adverse reactions, indicating that the incidence rate of complications in the EEN group was significantly lower than that in the TPN group (P<0.05). The postoperative evacuation time was earlier, hospitalization time was shorter and cost of postoperative hospitalization was less in the EEN group than those in the TPN group, and the differences were statistically significant (P<0.05). The blood glucose fluctuation values at fasting and 2 h after a meal in the TPN group were higher than those in the EEN group within 8 days after operation, and the differences were statistically significant (χ²=13.219, P=0.002; χ²=20.527, P<0.001). EEN support provides nutrition for patients with gastric cancer complicated with diabetes mellitus after radical gastrectomy, which is worthy of clinical promotion as it maintains good nutritional status, produces few postoperative complications and keeps the blood glucose level stable, by which the postoperative evacuation time is early, the hospitalization time is short and the cost is low.

Methylglyoxal-Mediated Stress Correlates with High Metabolic Activity and Promotes Tumor Growth in Colorectal Cancer

Cancer cells generally rely on aerobic glycolysis as a major source of energy. Methylglyoxal (MG), a dicarbonyl compound that is produced as a side product during glycolysis, is highly reactive and induces the formation of advanced glycation end-products that are implicated in several pathologies including cancer. All mammalian cells have an enzymatic defense against MG composed by glyoxalases GLO1 and GLO2 that converts MG to d-lactate. Colorectal cancer (CRC) is one of the most frequently occurring cancers with high morbidity and mortality. In this study, we used immunohistochemistry to examine the level of MG protein adducts, in a series of 102 CRC human tumors divided into four clinical stages. We consistently detected a high level of MG adducts and low GLO1 activity in high stage tumors compared to low stage ones suggesting a pro-tumor role for dicarbonyl stress. Accordingly, GLO1 depletion in CRC cells promoted tumor growth in vivo that was efficiently reversed using carnosine, a potent MG scavenger. Our study represents the first demonstration that MG adducts accumulation is a consistent feature of high stage CRC tumors. Our data point to MG production and detoxification levels as an important molecular link between exacerbated glycolytic activity and CRC progression.

Macrophage PPARγ inhibits Gpr132 to mediate the anti-tumor effects of rosiglitazone

Tumor-associated macrophage (TAM) significantly contributes to cancer progression. Human cancer is enhanced by PPARγ loss-of-function mutations, but inhibited by PPARγ agonists such as TZD diabetes drugs including rosiglitazone. However, it remains enigmatic whether and how macrophage contributes to PPARγ tumor-suppressive functions. Here we report that macrophage PPARγ deletion in mice not only exacerbates mammary tumor development but also impairs the anti-tumor effects of rosiglitazone. Mechanistically, we identify Gpr132 as a novel direct PPARγ target in macrophage whose expression is enhanced by PPARγ loss but repressed by PPARγ activation. Functionally, macrophage Gpr132 is pro-inflammatory and pro-tumor. Genetic Gpr132 deletion not only retards inflammation and cancer growth but also abrogates the anti-tumor effects of PPARγ and rosiglitazone. Pharmacological Gpr132 inhibition significantly impedes mammary tumor malignancy. These findings uncover macrophage PPARγ and Gpr132 as critical TAM modulators, new cancer therapeutic targets, and essential mediators of TZD anti-cancer effects.

DOI:http://dx.doi.org/10.7554/eLife.18501.001

The immune system can both contribute to cancer progression and restrain the growth of tumors. Some immune cells – called macrophages – create an inflammatory environment around a tumor, which can support the spread of the cancer cells.

Independent observations and experiments have shown that a protein called PPARγ can suppress the development and growth of tumors. Drugs called thiazolidinediones (or TZDs for short), which are normally used to treat type 2 diabetes, activate PPARγ and therefore have anti-tumor effects. However, it is not fully understood how PPARγ and TZDs suppress tumor development.

Cheng et al. hypothesized that the PPARγ protein and TZDs can inhibit the activity of the inflammatory macrophages that help tumors to develop. To test this, mice were genetically engineered so that their macrophages could not produce the PPARγ protein. These engineered mice were more likely to develop breast cancer than normal. Furthermore, the breast tumors in the modified mice did not shrink when they were treated with TZDs, whereas the tumors of normal mice did.

Cheng et al. also found that PPARγ inhibits the ability of macrophages to produce a protein called Gpr132, which itself contributes to inflammation and allows breast cancer cells to grow. Mice that were unable to produce Grp132 displayed less inflammation, and cancer growth was blocked. Drugs that inhibited the activity of Grp132 in normal mice also reduced the ability of breast tumors to spread.

Future experiments will need to examine exactly how the Gpr132 proteins produced by macrophages communicate with the cancer cells. Furthermore, developing new drugs that can inhibit Gpr132 could ultimately lead to more effective treatments for cancer.

DOI:http://dx.doi.org/10.7554/eLife.18501.002

The double trouble of metabolic diseases: the diabetes-cancer link

The recent recognition of the clinical association between type 2 diabetes (T2D) and several types of human cancer has been further highlighted by reports of antidiabetic drugs treating or promoting cancer. At the cellular level, a plethora of molecules operating within distinct signaling pathways suggests cross-talk between the multiple pathways at the interface of the diabetes–cancer link. Additionally, a growing body of emerging evidence implicates homeostatic pathways that may become imbalanced during the pathogenesis of T2D or cancer or that become chronically deregulated by prolonged drug administration, leading to the development of cancer in diabetes and vice versa. This notion underscores the importance of combining clinical and basic mechanistic studies not only to unravel mechanisms of disease development but also to understand mechanisms of drug action. In turn, this may help the development of personalized strategies in which drug doses and administration durations are tailored to individual cases at different stages of the disease progression to achieve more efficacious treatments that undermine the diabetes–cancer association.

Metformin Has a Positive Therapeutic Effect on Prostate Cancer in Patients With Type 2 Diabetes Mellitus

OBJECTIVE

Prostate cancer and type 2 diabetes mellitus (DM2) are both common diseases found in the elderly male population. The diabetic drug, metformin, has been shown to have antineoplastic properties and demonstrated better treatment outcomes when used as adjuvant therapy in patients with breast cancer. The hormonally-sensitive cancer analogous to breast cancer in men is prostate cancer. We investigated improved survival, lower risks of recurrences, and lower, more stable levels of prostate-specific antigen (PSA) in patients with DM2 along with prostate cancer on metformin.

METHODS

Patients with prostate cancer along with DM2 who remained on metformin were compared with controls who were not on metformin matched by age, weight, race and Gleason score cancer staging. The endpoints of our study included final PSA values, number of recurrences, metastases and number living for each group.

RESULTS

There were significantly fewer deaths (23% versus 10%), fewer recurrences (15% versus 8%), fewer metastases (5% versus 0%) and fewer secondary cancers (17% versus 6%) in the metformin group (P < 0.004). The final PSA value was lower in the metformin-treated group with a result approaching significance (P = 0.067). The primary treatments for prostate cancer (ie, surgery, radiation and androgen depletion) were found to be comparable in both the groups.

CONCLUSIONS

Our retrospective study shows that adjuvant metformin therapy leads to a better prognosis in prostate cancer. Not only are PSA levels controlled for several years but also there are significantly fewer cancer recurrences in metformin-treated patients. Overall, these results are promising and should be followed up with a prospective study to assess long-term survival.

Synergistic therapeutic effects of Schiff's base cross-linked injectable hydrogels for local co-delivery of metformin and 5-fluorouracil in a mouse colon carcinoma model

In situ formed hydrogels based on Schiff base reaction were formulated for the co-delivery of metformin (ME) and 5-fluorouracil (5FU). The reactive aldehyde-functionalized four-arm polyethylene glycol (PFA) was synthesized by end-capping of 4-arm PEG with 4-formylbenzoic acid (FA) and used as a cross-linking agent. The injectable hydrogels are designed through the quick gelation induced by the formation of covalent bonds via Schiff-base reaction of PFA with 4-arm poly (ethylene glycol)-b-poly (L-lysine) (PPLL). This formulation eliminated the need for metal catalysts and complicated processes in the preparation of in situ-forming hydrogels. In vitro degradation and drug release studies demonstrated that both ME and 5FU were released through PFA/PPLL hydrogels in a controlled and pH-dependent manner. When incubated with mouse colon adenocarcinoma cells (C26), the ME/5FU-incorporated PFA/PPLL hydrogels had synergistic inhibitory effects on the cell cycle progression and cell proliferation in colon cancer cells. After a single subcutaneous injection of the hydrogel containing ME/5FU beside the tumors of BALB/c mice inoculated with C26 cells, the dual-drug-loaded hydrogels displayed superior therapeutic activity resulted from a combination of p53-mediated G1 arrest and apoptosis in C26 cells. Hence, the Schiff's base cross-linked hydrogels containing ME and 5FU may have potential therapeutic applications in the treatments of colon cancer.

Metformin: risk-benefit profile with a focus on cancer

INTRODUCTION

Epidemiological evidence suggests an increased incidence of cancer in obese, prediabetic, and diabetic patients and a reduced risk of cancer incidence and mortality in diabetic patients on metformin compared with other antidiabetic drugs. In vitro studies support the efficacy of metformin in cancer therapy and prevention. Although metformin seems to be promising as a cancer chemopreventive or therapeutic drug, the principal consideration is whether metformin will be effective in cancer clinical trials for nondiabetic subjects or only in diabetics or subjects with insulin resistance. Safety of metformin is even more important in treating nondiabetic patients.

AREAS COVERED

The present review focuses on epidemiological data and clinical trials testing the efficacy of metformin on cancer, the safety in nondiabetic patients and the future development of this promising drug.

EXPERT OPINION

Meta-analyses of epidemiological in which metformin treatment has been used for diabetic patients show a positive trend for benefit; nevertheless, clinical data outcomes are preliminary and the results of ongoing trials are awaited. The different types of cancer, heterogeneity of populations and presence of comorbidity make it difficult to determine the benefits of metformin in cancer prevention and treatment.

TRB3 links insulin/IGF to tumour promotion by interacting with p62 and impeding autophagic/proteasomal degradations

High insulin/IGF is a biologic link between diabetes and cancers, but the underlying molecular mechanism remains unclear. Here we report a previously unrecognized tumour-promoting mechanism for stress protein TRB3, which mediates a reciprocal antagonism between autophagic and proteasomal degradation systems and connects insulin/IGF to malignant promotion. We find that several human cancers express higher TRB3 and phosphorylated insulin receptor substrate 1, which correlates negatively with patient's prognosis. TRB3 depletion protects against tumour-promoting actions of insulin/IGF and attenuates tumour initiation, growth and metastasis in mice. TRB3 interacts with autophagic receptor p62 and hinders p62 binding to LC3 and ubiquitinated substrates, which causes p62 deposition and suppresses autophagic/proteasomal degradation. Several tumour-promoting factors accumulate in cancer cells to support tumour metabolism, proliferation, invasion and metastasis. Interrupting TRB3/p62 interaction produces potent antitumour efficacies against tumour growth and metastasis. Our study opens possibility of targeting this interaction as a potential novel strategy against cancers with diabetes.

Metabolic Burden and Disease and Mortality Risk Associated with Impaired Fasting Glucose in Elderly Adults

OBJECTIVES

To examine whether impaired fasting glucose (IFG) represents an intermediary condition between normal fasting glucose and diabetes mellitus and, specifically, whether elderly adults with IFG have higher disease burden, cardiovascular risk, and systemic inflammation and higher 2-year mortality and incident disease.

DESIGN

Prospective observational study.

SETTING

Population-derived cohort.

PARTICIPANTS

Individuals with a mean age of 78.6 ± 4.7 (N = 945).

MEASUREMENTS

Disease was ascertained using a standardized questionnaire at baseline and 2 years. Fasting metabolic, inflammatory, and oxidative metabolism markers were measured. Disease prevalence, cardiovascular risk, and biochemical markers were compared to determine disease burden and metabolic disturbances in IFG. Adjusted odds ratios (ORs) for 2-year all-cause mortality and incident disease were determined.

RESULTS

IFG prevalence was 41%. Individuals with IFG had higher baseline rates of heart disease than those with normal fasting glucose (NFG), similar to that in individuals with diabetes mellitus. IFG was characterized by higher inflammatory markers and oxidative metabolism end products and was an intermediary between NFG and diabetes mellitus for triglycerides and malondialdehyde. Discriminant analysis showed that IFG was independently associated with stroke and higher triglycerides and oxidative stress. Two-year all-cause mortality was 3.9%. The 2-year adjusted ORs for all-cause mortality, incident cardiac disease, stroke, and cancer were similar between IFG and NFG, using both American Diabetes Association and World Health Organization IFG criteria. IFG did not predict secondary cardiac events, stroke, or cancer.

CONCLUSION

IFG was an intermediary condition for heart disease, inflammation, and oxidative stress in elderly adults but not for 2-year incident disease or all-cause mortality. Longer-term prospective studies are needed to clarify whether IFG in elderly adults portends greater morbidity and mortality.

Effect of Melatonin Intake on Oxidative Stress Biomarkers in Male Reproductive Organs of Rats under Experimental Diabetes

This study investigated the antioxidant system response of male reproductive organs during early and late phases of diabetes and the influence of melatonin treatment. Melatonin was administered to five-week-old Wistar rats throughout the experiment, in drinking water (10 μg/kg b.w). Diabetes was induced at 13 weeks of age by streptozotocin (4.5 mg/100 g b.w., i.p.) and animals were euthanized with 14 or 21 weeks old. Activities of catalase (CAT), glutathione-S-transferase (GST), glutathione peroxidase (GPx), and lipid peroxidation were evaluated in prostate, testis, and epididymis. The enzymes activities and lipid peroxidation were not affected in testis and epididymis after one or eight weeks of diabetes. Prostate exhibited a 3-fold increase in GPx activity at short-term diabetes and at long-term diabetes there were 2- and 3-fold increase in CAT and GST, respectively (p ≤ 0.01). Melatonin treatment to healthy rats caused a 47% increase in epididymal GPx activity in 14-week-old rats. In prostate, melatonin administration normalized GST activity at both ages and mitigated GPx at short-term and CAT at long-term diabetes. The testis and epididymis were less affected by diabetes than prostate. Furthermore, melatonin normalized the enzymatic disorders in prostate demonstrating its effective antioxidant role, even at low dosages.

When Anti-Aging Studies Meet Cancer Chemoprevention: Can Anti-Aging Agent Kill Two Birds with One Blow?

Recent evidence has strongly supported that the rate of aging is controlled, at least to some extent, by evolutionarily conserved nutrient sensing pathways (e.g. the insulin/IGF-1-signaling, mTOR, AMPK, and sirtuins) from worms to humans. These pathways are also commonly involved in carcinogenesis and cancer metabolism. Agents (e.g. metformin, resveratrol, and Rhodiola) that target these nutrient sensing pathways often have both anti-aging and anti-cancer efficacy. These agents not only reprogram energy metabolism of malignant cells, but also target normal postmitotic cells by suppressing their conversion into senescent cells, which confers systematic metabolism benefits. These agents are fundamentally different from chemotherapy (e.g. paclitaxel and doxorubicin) or radiation therapy that causes molecular damage (e.g. DNA and protein damages) and thereby no selection resistance may be expected. By reviewing molecular mechanisms of action, epidemiological evidence, experimental data in tumor models, and early clinical study results, this review provides information supporting the promising use of agents with both anti-aging and anti-cancer efficacy for cancer chemoprevention.

The association between diabetes and breast cancer stage at diagnosis: a population-based study

Women with diabetes have higher breast cancer incidence and mortality. The purpose of this study was to examine the impact of diabetes on stage at breast cancer diagnosis, as a possible reason for their higher mortality. Using population-based health databases from Ontario, Canada, this retrospective cohort study examined stage at diagnosis (II, III, or IV vs I) among women aged 20-105 years who were newly diagnosed with invasive breast cancer between 2007 and 2012. We compared those with diabetes to those without diabetes. Diabetes was defined based on medical records using a validated algorithm. Among 38,407 women with breast cancer, 6115 (15.9 %) women had diabetes. Breast cancer patients with diabetes were significantly more likely to present with advanced-stage breast cancer than those without diabetes. After adjustment for mammograms and other covariates, diabetes was associated with a significantly increased risk of Stage II [adjusted odds ratio (aOR) 1.14, 95 % confidence interval (CI) 1.07, 1.22], Stage III (aOR 1.21, 95 % CI 1.11, 1.33), and Stage IV (aOR 1.16, 95 % CI 1.01, 1.33) versus Stage I breast cancer. Women with diabetes had a higher risk of lymph node metastases (aOR 1.16, 95 % CI 1.06, 1.27) and tumors with size over 2 cm (aOR 1.16, 95 % CI 1.06, 1.28). Diabetes was associated with more advanced-stage breast cancer, even after accounting for differences in screening mammogram use and other factors. Our findings suggest that diabetes may predispose to more aggressive breast cancer, which may be a contributor to their higher cancer mortality.

Metformin reduces serum CA199 levels in type 2 diabetes Chinese patients with time-effect and gender difference

BACKGROUND

This study was designed to clarify the influence of metformin on serum carbohydrate antigen 199 (CA199) levels and its associated factors in Chinese type 2 diabetes mellitus (T2DM) patients.

SUBJECTS AND METHODS

In total, 1,253 T2DM patients were enrolled, including a non-metformin group (n = 616), a short-term metformin group (at least 1 week to 2 years; n=325), and a long-term metformin group (≥ 2 years; n = 312). Their clinical and biochemical characteristics were collected and compared. After 1 year, the biochemical parameters were re-examined in 296 patients. Sex hormones were determined, and associations between CA199 and other variables were assessed.

RESULTS

At baseline, the incidence of abnormal CA199 levels was 14.7%, 8.9%, and 4.7% in the non-metformin, short-term metformin, and long-term metformin groups, respectively. CA199 levels in females were significantly higher than in males (P < 0.01) and decreased significantly with the time of taking metformin (25.60 ± 13.68 U/mL in non-metformin controls vs. 17.62 ± 10.87 U/mL in the short-term group vs. 10.54 ± 8.14 U/mL in the long-term group; P = 0.000). The correlation and multiple stepwise regression analysis revealed that glycosylated hemoglobin, metformin, gender, total cholesterol, and follicle-stimulating hormone were independent impact factors on CA199 concentrations (all P < 0.05). Binary logistic regression revealed that the risk of abnormal CA199 concentrations of the total population with short-term metformin or long-term metformin treatment decreased 11% (odds ratio = 0.89; P = 0.001) and 30% (odds ratio = 0.70; P = 0.000), respectively, at baseline. After a 1-year follow-up, the incidence of high CA199 level decreased in both the short-term and the long-term metformin group compared with that of controls (P < 0.05). The extent of CA199 decrease in the long-term metformin group was the greatest (-17% vs. -4.9% in the short-term group vs. 3% in controls, P = 0.000), and the group's risk of high blood CA199 level was reduced 67% (odds ratio = 0.33; P = 0.023). The reduction in women was more apparent than that in men (-18% vs. -5%, P = 0.000).

CONCLUSIONS

Metformin therapy reduced the CA199 level in Chinese T2DM patients, and its greatest decrease occurred in women with longer therapeutic time.

Metformin in cancer prevention and therapy

The prevalence of diabetes is dramatically increasing worldwide. The results of numerous epidemiological studies indicate that diabetic population is not only at increased risk of cardiovascular complications, but also at substantially higher risk of many forms of malignancies. The use of metformin, the most commonly prescribed drug for type 2 diabetes, was repeatedly associated with the decreased risk of the occurrence of various types of cancers, especially of pancreas and colon and hepatocellular carcinoma. This observation was also confirmed by the results of numerous meta-analyses. There are however, several unanswered questions regarding the exact mechanism of the anticancer effect of metformin as well as its activity against various types of cancer both in diabetic and nondiabetic populations. In the present work we discuss the proposed mechanism(s) of anticancer effect of metformin and preclinical and clinical data suggesting its anticancer effect in different populations.

Long-term globular adiponectin administration improves adipose tissue dysmetabolism in high-fat diet-fed Wistar rats

Adiponectin administration to obese or type 2 diabetic patients is still far off, due to its expensive costs and absence of studies demonstrating the effectiveness of its chronic administration. We performed long-term globular adiponectin administration, testing its usefulness in improving adipose tissue metabolism. Adiponectin (98 υg/day) was administered through a subcutaneous minipump with continued release (28 days) to Wistar rats fed a high-fat diet. Adiponectin decreased body weight and adipocyte size, while decreasing circulating leptin levels. More, adiponectin was able to increase IkappaBalpha and PPARgamma levels and to prevent high-fat diet-induced impairment of insulin signalling, especially in epididymal adipose tissue. This resulted in improved glucose profile. High-fat diet caused an impairment of lipolysis in epididymal adipose tissue, which was partially restored by adiponectin treatment. Long-term globular adiponectin administration was able to improve pathways of insulin signalling and lipid storage in adipose tissue of high-fat diet-fed rats, contributing to a better metabolic profile.

ADCY5 couples glucose to insulin secretion in human islets

Single nucleotide polymorphisms (SNPs) within the ADCY5 gene, encoding adenylate cyclase 5, are associated with elevated fasting glucose and increased type 2 diabetes (T2D) risk. Despite this, the mechanisms underlying the effects of these polymorphic variants at the level of pancreatic β-cells remain unclear. Here, we show firstly that ADCY5 mRNA expression in islets is lowered by the possession of risk alleles at rs11708067. Next, we demonstrate that ADCY5 is indispensable for coupling glucose, but not GLP-1, to insulin secretion in human islets. Assessed by in situ imaging of recombinant probes, ADCY5 silencing impaired glucose-induced cAMP increases and blocked glucose metabolism toward ATP at concentrations of the sugar >8 mmol/L. However, calcium transient generation and functional connectivity between individual human β-cells were sharply inhibited at all glucose concentrations tested, implying additional, metabolism-independent roles for ADCY5. In contrast, calcium rises were unaffected in ADCY5-depleted islets exposed to GLP-1. Alterations in β-cell ADCY5 expression and impaired glucose signaling thus provide a likely route through which ADCY5 gene polymorphisms influence fasting glucose levels and T2D risk, while exerting more minor effects on incretin action.

The influence of diabetes severity on receipt of guideline-concordant treatment for breast cancer

Diabetes severity may influence breast cancer treatment choices. We examined whether receipt of guideline-concordant breast cancer treatment varied with diabetes severity. Cancer registry data from seven states regarding 6,912 stage I-III breast cancers were supplemented by medical record abstraction and physician verification. We used logistic regression models to examine associations of diabetes severity with guideline-concordant locoregional treatment, adjuvant chemotherapy, and hormonal therapy adjusted for sociodemographics, comorbidity, and tumor characteristics. We defined guideline concordance using National Comprehensive Cancer Network guidelines, and diabetes and comorbidities using the Adult Comorbidity Evaluation-27 index. After adjustment, there was significant interaction of diabetes severity with age for locoregional treatment (p = 0.001), with many diabetic women under age 70 less frequently receiving guideline-concordant treatment than non-diabetic women. Among similarly aged women, guideline concordance was lower for women with mild diabetes in their late fifties through mid-sixties, and with moderate/severe diabetes in their late forties to early sixties. Among women in their mid-seventies to early eighties, moderate/severe diabetes was associated with increased guideline concordance. For adjuvant chemotherapy, moderate/severe diabetes was less frequently associated with guideline concordance than no diabetes [OR 0.58 (95 % CI 0.36-0.94)]. Diabetes was not associated with guideline-concordant hormonal treatment (p = 0.929). Some diabetic women were less likely to receive guideline-concordant treatment for stage I-III breast cancer than non-diabetic women. Diabetes severity was associated with lower guideline concordance for locoregional treatment among middle-aged women, and lower guideline concordance for adjuvant chemotherapy. Differences were not explained by comorbidity and may contribute to potentially worse breast cancer outcomes.

Cancer risks from diabetes therapies: evaluating the evidence

Epidemiological studies have identified positive associations between diabetes, obesity and cancer. Insulin, metformin and thiazolidinediones (TDZs) are among the major diabetes therapies that improve glycaemic control by acting via molecular targets including the insulin receptor and insulin-like growth factor pathways, adenosine monophosphate-activated kinase and peroxisome proliferator-activated receptor γ. It is well-established that clinical application of insulin and TDZs is associated with weight gain, but the potential of these therapies to promote tumourigenesis is less well-studied. In addition, although anti-tumour properties of metformin have been proposed, recently published data do not support a protective effect of metformin against cancer in diabetic patients. Given that diabetes and cancer each account for 8% and 13% of global deaths and there is a substantial financial burden incurred by both disorders, developing diabetes therapies that are safe, efficacious and cost-effective has never been more desirable. This timely review examines recent progress in delineating the molecular mechanisms responsible for the anti-diabetic actions of insulin, metformin and TZDs and considers evidence implicating these therapies in cell transformation and tumourigenesis. In addition, since the endocannabinoid signalling system (ECS) is now considered a therapeutic target and biomarker candidate for hyperglycaemia, obesity and cell growth, a brief section covering recent scientific advances regarding the ECS, particularly its functions in regulating glucose metabolism and cell survival, is also included in this review.

Common mechanisms of dysfunctional adipose tissue and obesity-related cancers

The relation between cancer and metabolic disorders was recognized several decades ago, but the underlying mechanisms involved in cancer development and progression remain obscure. In the last years, many groups have been studying systemic adipose tissue markers in cancer patients. However, few consistent results were obtained. On the other hand, several studies revealed many aspects of adipose tissue physiology in obesity. Nowadays, it is recognized that excessive lipid uptake in adipocytes leads to hypertrophy and consequently to metabolic dysregulation, hypoxia, inflammation, impaired adipocytokine expression and angiogenesis, insulin resistance and macrophage recruitment. In obese patients, tumours commonly colocalize with excessive adipose tissue accumulation, and most of the features of hypertrophic adipose tissue are observed in cancer patients, namely breast and colon. This review aimed to summarize pathological adipose tissue alterations that may contribute to cancer aetiology and development.

Metformin: an old but still the best treatment for type 2 diabetes

The management of T2DM requires aggressive treatment to achieve glycemic and cardiovascular risk factor goals. In this setting, metformin, an old and widely accepted first line agent, stands out not only for its antihyperglycemic properties but also for its effects beyond glycemic control such as improvements in endothelial dysfunction, hemostasis and oxidative stress, insulin resistance, lipid profiles, and fat redistribution. These properties may have contributed to the decrease of adverse cardiovascular outcomes otherwise not attributable to metformin's mere antihyperglycemic effects. Several other classes of oral antidiabetic agents have been recently launched, introducing the need to evaluate the role of metformin as initial therapy and in combination with these newer drugs. There is increasing evidence from in vivo and in vitro studies supporting its anti-proliferative role in cancer and possibly a neuroprotective effect. Metformin's negligible risk of hypoglycemia in monotherapy and few drug interactions of clinical relevance give this drug a high safety profile. The tolerability of metformin may be improved by using an appropiate dose titration, starting with low doses, so that side-effects can be minimized or by switching to an extended release form. We reviewed the role of metformin in the treatment of patients with type 2 diabetes and describe the additional benefits beyond its glycemic effect. We also discuss its potential role for a variety of insulin resistant and pre-diabetic states, obesity, metabolic abnormalities associated with HIV disease, gestational diabetes, cancer, and neuroprotection.

Animal models of GWAS-identified type 2 diabetes genes

More than 65 loci, encoding up to 500 different genes, have been implicated by genome-wide association studies (GWAS) as conferring an increased risk of developing type 2 diabetes (T2D). Whilst mouse models have in the past been central to understanding the mechanisms through which more penetrant risk genes for T2D, for example, those responsible for neonatal or maturity-onset diabetes of the young, only a few of those identified by GWAS, notably TCF7L2 and ZnT8/SLC30A8, have to date been examined in mouse models. We discuss here the animal models available for the latter genes and provide perspectives for future, higher throughput approaches towards efficiently mining the information provided by human genetics.

The genetics of type 2 diabetes and its clinical relevance

The increasing worldwide prevalence of type 2 diabetes (T2D) motivates efforts to use genetics to define key pathways involved in disease predisposition, and thereby to improve management of the disease. Research over the past 5 years has taken the total number of genetic loci implicated in T2D susceptibility beyond 60, and the emphasis is now shifting to the translation of these genetic insights into clinical value. Clinical translation may flow from the identification of novel therapeutic targets, but opportunities also exist with respect to individual prediction, diagnostic biomarkers and therapeutic optimization. To date, the main clinical impact has been seen for relatively rare, monogenic forms of diabetes rather than common T2D. However, the advent of high throughput sequencing approaches may herald discovery of rare and low frequency variants that offer greater translational potential.

PTEN mutations as a cause of constitutive insulin sensitivity and obesity

BACKGROUND

Epidemiologic and genetic evidence links type 2 diabetes, obesity, and cancer. The tumor-suppressor phosphatase and tensin homologue (PTEN) has roles in both cellular growth and metabolic signaling. Germline PTEN mutations cause a cancer-predisposition syndrome, providing an opportunity to study the effect of PTEN haploinsufficiency in humans.

METHODS

We measured insulin sensitivity and beta-cell function in 15 PTEN mutation carriers and 15 matched controls. Insulin signaling was measured in muscle and adipose-tissue biopsy specimens from 5 mutation carriers and 5 well-matched controls. We also assessed the effect of PTEN haploinsufficiency on obesity by comparing anthropometric indexes between the 15 patients and 2097 controls from a population-based study of healthy adults. Body composition was evaluated by means of dual-emission x-ray absorptiometry and skinfold thickness.

RESULTS

Measures of insulin resistance were lower in the patients with a PTEN mutation than in controls (e.g., mean fasting plasma insulin level, 29 pmol per liter [range, 9 to 99] vs. 74 pmol per liter [range, 22 to 185]; P=0.001). This finding was confirmed with the use of hyperinsulinemic euglycemic clamping, showing a glucose infusion rate among carriers 2 times that among controls (P=0.009). The patients' insulin sensitivity could be explained by the presence of enhanced insulin signaling through the PI3K-AKT pathway, as evidenced by increased AKT phosphorylation. The PTEN mutation carriers were obese as compared with population-based controls (mean body-mass index [the weight in kilograms divided by the square of the height in meters], 32 [range, 23 to 42] vs. 26 [range, 15 to 48]; P<0.001). This increased body mass in the patients was due to augmented adiposity without corresponding changes in fat distribution.

CONCLUSIONS

PTEN haploinsufficiency is a monogenic cause of profound constitutive insulin sensitization that is apparently obesogenic. We demonstrate an apparently divergent effect of PTEN mutations: increased risks of obesity and cancer but a decreased risk of type 2 diabetes owing to enhanced insulin sensitivity. (Funded by the Wellcome Trust and others.).

Metformin: multi-faceted protection against cancer

The biguanide metformin, a widely used drug for the treatment of type 2 diabetes, may exert cancer chemopreventive effects by suppressing the transformative and hyperproliferative processes that initiate carcinogenesis. Metformin's molecular targets in cancer cells (e.g., mTOR, HER2) are similar to those currently being used for directed cancer therapy. However, metformin is nontoxic and might be extremely useful for enhancing treatment efficacy of mechanism-based and biologically targeted drugs. Here, we first revisit the epidemiological, preclinical, and clinical evidence from the last 5 years showing that metformin is a promising candidate for oncology therapeutics. Second, the anticancer effects of metformin by both direct (insulin-independent) and indirect (insulin-dependent) mechanisms are discussed in terms of metformin-targeted processes and the ontogenesis of cancer stem cells (CSC), including Epithelial-to-Mesenchymal Transition (EMT) and microRNAs-regulated dedifferentiation of CSCs. Finally, we present preliminary evidence that metformin may regulate cellular senescence, an innate safeguard against cellular immortalization. There are two main lines of evidence that suggest that metformin's primary target is the immortalizing step during tumorigenesis. First, metformin activates intracellular DNA damage response checkpoints. Second, metformin attenuates the anti-senescence effects of the ATP-generating glycolytic metabotype-the Warburg effect-, which is required for self-renewal and proliferation of CSCs. If metformin therapy presents an intrinsic barrier against tumorigenesis by lowering the threshold for stress-induced senescence, metformin therapeutic strategies may be pivotal for therapeutic intervention for cancer. Current and future clinical trials will elucidate whether metformin has the potential to be used in preventive and treatment settings as an adjuvant to current cancer therapeutics.

HbA1C and cancer risk in patients with type 2 diabetes--a nationwide population-based prospective cohort study in Sweden

Background

Diabetes is associated with increased cancer risk. The underlying mechanisms remain unclear. Hyperglycemia might be one risk factor. HbA1c is an indicator of the blood glucose level over the latest 1 to 3 months. This study aimed to investigate association between HbA1c level and cancer risks in patients with type 2 diabetes based on real life situations.

Methods

This is a cohort study on 25,476 patients with type 2 diabetes registered in the Swedish National Diabetes Register from 1997–1999 and followed until 2009. Follow-up for cancer was accomplished through register linkage. We calculated incidences of and hazard ratios (HR) for cancer in groups categorized by HbA1c ≤58 mmol/mol (7.5%) versus >58 mmol/mol, by quartiles of HbA1c, and by HbA1c continuously at Cox regression, with covariance adjustment for age, sex, diabetes duration, smoking and insulin treatment, or adjusting with a propensity score.

Results

Comparing HbA1c >58 mmol/mol with ≤58 mmol/mol, adjusted HR for all cancer was 1.02 [95% CI 0.95–1.10] using baseline HbA1c, and 1.04 [95% CI 0.97–1.12] using updated mean HbA1c, and HRs were all non-significant for specific cancers of gastrointestinal, kidney and urinary organs, respiratory organs, female genital organs, breast or prostate. Similarly, no increased risks of all cancer or the specific types of cancer were found with higher quartiles of baseline or updated mean HbA1c, compared to the lowest quartile. HR for all cancer was 1.01 [0.98–1.04] per 1%-unit increase in HbA1c used as a continuous variable, with non-significant HRs also for the specific types of cancer per unit increase in HbA1c.

Conclusions

In this study there were no associations between HbA1c and risks for all cancers or specific types of cancer in patients with type 2 diabetes.

Pioglitazone: Indian perspective

Pioglitazone was approved in 1999 as an adjunct to exercise and diet to improve glycemic control in adults with type 2 diabetes mellitus, primarily by reducing insulin resistance. Beyond these effects on glucose metabolism, pioglitazone has positive effects on lipid metabolism, blood pressure, endothelial function, adiponectin, and C-reactive protein levels. These make pioglitazone treatment effective beyond glucose control. Pioglitazone generally has been viewed as a safer option for patients who warrant treatment with a thiazolidinedione-class drug. There has been some recent data on cancer incidence in patients on pioglitazone, which is currently being reviewed by drug regulatory authorities in the United States and in Europe. Given the benefits of pioglitazone, alone and in combination, it would be appropriate to continue judicious use of the drug in patients who may benefit from its use.

Diabetes, treatments for diabetes and their effect on cancer incidence and mortality: attempts to disentangle the web of associations

The association between type 2 diabetes and some types of cancer is well established and the complexity of this association is receiving increasing recognition. Many factors influence the risk of both diabetes and cancer including age, sex, ethnicity, socioeconomic status, obesity/insulin resistance, diet (including alcohol intake), physical activity levels and smoking history. The presence of diabetes may influence the uptake of cancer screening. Using an experimental approach to investigate the effect of better control of diabetes is helpful in assessing whether hyperglycaemia has a causal relationship with cancer. Diabetes treatments may influence the risk of cancer independently of their effect on glycaemia and complicate investigation of the association between diabetes and cancer. This article discusses the complexity involved in attempting to clarify the factors that contribute to the associations between diabetes, hyperglycaemia, diabetes treatment and cancer.

Insulin glargine use and short-term incidence of malignancies - a three-year population-based observation

AIMS/HYPOTHESIS

To further investigate the association of cancer occurrence with the use of insulin glargine.

METHODS

We followed 114 838 individuals using insulin between 1 July and 31 December 2005. From 1 January 2006 to 31 December 2008, we noted the occurrence of malignancies (cohort I). Insulin users between 1 July and 31 December 2006 were followed for the occurrence of malignancies in 2007 and 2008 (cohort II). Users of insulin during three consecutive six-month periods from 1 July 2005 to 31 December 2006 were followed for the occurrence of malignancies in 2007 and 2008 (cohort III). The Prescribed Drug Register, the Cancer Register, and the Causes of Death Register were used to obtain information on targeted person-time and outcome. We retrieved variables reflecting potential confounding factors from the Swedish National Diabetes Register, the Prescribed Drug Register, the Patient Register, the Medical Birth Register and the National Education Register. With Poisson regression we evaluated the association between insulin use and malignancy outcome with adjustment for confounders.

RESULTS

The adjusted incidence rate ratio (and 95% confidence interval) for women who used insulin glargine alone compared with those who used other types of insulin, was 1.60 (1.10-2.32) for breast cancer but included 1.0 for malignancy outcomes other than breast cancer for men and women when analyzing cohort I with follow-up in 2006-2008. For cohort II and III the corresponding incidence rate ratios were 1.38 (0.87-2.18), and 0.87 (0.41-1.85), respectively.

CONCLUSION/INTERPRETATION

We do not see an increased risk during 2008 for breast cancer in the insulin glargine group. We need data for additional years before we can state with reasonable certainty that the increase in breast cancer incidence that we observed in Sweden in 2006 and 2007 was due to a random fluctuation or whether there is an association with the use of insulin glargine.