Analysis of signaling pathways related to cell proliferation stimulated by insulin analogs in human mammary epithelial cell lines

Effect of metformin on incidence, recurrence, and mortality in prostate cancer patients: integrating evidence from real-world studies

PURPOSE

Metformin has been suggested to reduce the risk of cancer. However, previous studies have been inconsistent regarding the relationship between metformin use and the risk of occurrence of prostate cancer (PCa). The purpose of this study was to assess the effect of metformin on clinical outcomes in patients with PCa in a meta-analysis and to explore the possible dose-response relationship.

METHODS

A systematic literature search was conducted in 10 electronic databases and 4 registries. The combined relative risks (RRs) were calculated using a random-effects model with 95% confidence interval (CIs) to assess the effect of metformin on the risk of PCa. Relevant subgroup analyses and sensitivity analyses were performed.

RESULTS

The across studies results show that metformin use associated with lower incidence of PCa (RR: 0.82, 95% CI: 0.74-0.91). Metformin use was also found to reduce PCa recurrence, but the results were not statistically significant (RR: 0.97, 95% CI: 0.81-1.15). Metformin use was not associated with PCa mortality (RR: 0.94, 95% CI: 0.81-1.09). The results of subgroup analyses indicated that the type of study was a cohort study and the population came from both Asia and Europe showed that taking metformin reduced the incidence of PCa. A linear correlation was found between the duration of metformin use and its protective effect.

CONCLUSIONS

This meta-analysis revealed an independent correlation between metformin use and reduced incidence of PCa. Metformin use was not associated with either PCa recurrence rate or mortality. Furthermore, the effect of metformin on PCa incidence was found to be related to duration.

Associations between Diabetes Mellitus and Selected Cancers

Cancer is one of the major causes of mortality and is the second leading cause of death. Diabetes mellitus is a serious and growing problem worldwide, and its prevalence continues to grow; it is the 12th leading cause of death. An association between diabetes mellitus and cancer has been suggested for more than 100 years. Diabetes is a common disease diagnosed among patients with cancer, and evidence indicates that approximately 8-18% of patients with cancer have diabetes, with investigations suggesting an association between diabetes and some particular cancers, increasing the risk for developing cancers such as pancreatic, liver, colon, breast, stomach, and a few others. Breast and colorectal cancers have increased from 20% to 30% and there is a 97% increased risk of intrahepatic cholangiocarcinoma or endometrial cancer. On the other hand, a number of cancers and cancer therapies increase the risk of diabetes mellitus. Complications due to diabetes in patients with cancer may influence the choice of cancer therapy. Unfortunately, the mechanisms of the associations between diabetes mellitus and cancer are still unknown. The aim of this review is to summarize the association of diabetes mellitus with selected cancers and update the evidence on the underlying mechanisms of this association.

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.

Associations between serum glucose, insulin, insulin resistance and the risk of incident primary liver cancer or chronic liver disease mortality: a nested case-control study

BACKGROUND

To evaluate the associations between pre-diagnostic levels of serum insulin, glucose and insulin resistance (HOMA-IR) and future risk of incident primary liver cancer (PLC) or chronic liver disease (CLD)-related mortality.

METHODS

We used a nested case-control design to evaluate subjects over 22 years of follow-up. Glucose, insulin, and three markers of hepatitis B virus (HBV) and hepatitis C virus were measured in fasting baseline serum from 119 incident PLCs, 157 CLD-death cases and 512 matched controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression to estimate the associations between insulin, glucose, HOMA-IR and the risk of PLC or CLD death.

RESULTS

Compared with the lowest quartile of insulin, multivariable adjusted models showed that subjects in the highest quartile had elevated odds of developing PLC (ORQ4/Q1 = 2.42, 95% CI = 1.26-4.75, Ptrend = 0.007), particularly in HBV-positive subjects (Pinteraction = 0.040), and of CLD death (ORQ4/Q1 = 1.80, 95% CI = 1.02-3.21, Ptrend = 0.018). For glucose, in the HBV-positive group, subjects in the fourth quartile had an increased risk of PLC (ORQ4/Q1 = 2.18, 95% CI = 1.07-4.60, Ptrend = 0.009), and of CLD mortality (ORQ4/Q1 = 1.75, 95% CI = 0.95-3.28, Ptrend = 0.019). Subjects with the highest HOMA-IR values had a threefold risk of developing PLC (ORQ4/Q1 = 2.94, 95% CI = 1.54-5.87, Ptrend = 0.001), and a twofold risk of CLD death (ORQ4/Q1 = 2.20, 95% CI = 1.25-3.94, Ptrend = 0.005).

CONCLUSIONS

We found that serum insulin and HOMA-IR could potentially be risk factors for PLC or CLD death.

Time-restricted feeding normalizes hyperinsulinemia to inhibit breast cancer in obese postmenopausal mouse models

Accumulating evidence indicates that obesity with its associated metabolic dysregulation, including hyperinsulinemia and aberrant circadian rhythms, increases the risk for a variety of cancers including postmenopausal breast cancer. Caloric restriction can ameliorate the harmful metabolic effects of obesity and inhibit cancer progression but is difficult to implement and maintain outside of the clinic. In this study, we aim to test a time-restricted feeding (TRF) approach on mouse models of obesity-driven postmenopausal breast cancer. We show that TRF abrogates the obesity-enhanced mammary tumor growth in two orthotopic models in the absence of calorie restriction or weight loss. TRF also reduces breast cancer metastasis to the lung. Furthermore, TRF delays tumor initiation in a transgenic model of mammary tumorigenesis prior to the onset of obesity. Notably, TRF increases whole-body insulin sensitivity, reduces hyperinsulinemia, restores diurnal gene expression rhythms in the tumor, and attenuates tumor growth and insulin signaling. Importantly, inhibition of insulin secretion with diazoxide mimics TRF whereas artificial elevation of insulin through insulin pumps implantation reverses the effect of TRF, suggesting that TRF acts through modulating hyperinsulinemia. Our data suggest that TRF is likely to be effective in breast cancer prevention and therapy.

Rethinking the Relationship between Insulin and Cancer

In addition to being a major metabolic hormone, insulin is also a growth factor with a mitogenic effect on all cells, more marked in malignant cells that often overexpress the insulin receptor. In patients with metabolic diseases characterized by hyperinsulinemia (obesity, type 2 diabetes, and metabolic syndrome), the incidence of several types of cancer is increased, as is cancer-related mortality. Because of the worldwide growing prevalence of metabolic diseases and the diffuse use of insulin and its analogs for treating diabetes, the relationship between insulin and cancer has become a clinically relevant issue. Clinical studies have not clarified the degree to which hyperinsulinemia can influence cancer occurrence and prognosis. To better understand this issue, an improved scientific approach is required, with more careful consideration of the mechanisms related to hyperinsulinemia and carcinogenesis.

Review of Associations Between Type 2 Diabetes and Cancer

Debate is ongoing regarding the relationship between type 2 diabetes and cancer, and the pathways linking the two are incompletely understood. Some posit that the relationship hinges on a common predisposing factor such as obesity, insulin resistance, or chronic inflammation that increases the risk of cancer independently. Others speculate that diabetes acts as an independent risk factor for cancer because of other molecular pathways and interactions. Additionally, antidiabetic medications have been associated with changes in cancer risk. This review presents a summary of the latest studies and data concerning the relationships among type 2 diabetes, antidiabetic medications, cancer risk, and cancer prognosis.

Manipulation of Metabolic Pathways and Its Consequences for Anti-Tumor Immunity: A Clinical Perspective

In the relatively short history of anti-tumor treatment, numerous medications have been developed against a variety of targets. Intriguingly, although many anti-tumor strategies have failed in their clinical trials, metformin, an anti-diabetic medication, demonstrated anti-tumor effects in observational studies and even showed its synergistic potential with immune checkpoint inhibitors (ICIs) in subsequent clinical studies. Looking back from bedside-to-bench, it may not be surprising that the anti-tumor effect of metformin derives largely from its ability to rewire aberrant metabolic pathways within the tumor microenvironment. As one of the most promising breakthroughs in oncology, ICIs were also found to exert their immune-stimulatory effects at least partly via rewiring metabolic pathways. These findings underscore the importance of correcting metabolic pathways to achieve sufficient anti-tumor immunity. Herein, we start by introducing the tumor microenvironment, and then we review the implications of metabolic syndrome and treatments for targeting metabolic pathways in anti-tumor therapies. We further summarize the close associations of certain aberrant metabolic pathways with impaired anti-tumor immunity and introduce the therapeutic effects of targeting these routes. Lastly, we go through the metabolic effects of ICIs and conclude an overall direction to manipulate metabolic pathways in favor of anti-tumor responses.

Improving health engagement and lifestyle management for breast cancer survivors with diabetes

Breast cancer survivors with type 2 diabetes are at high risk for cancer recurrence, serious health complications, more severe symptoms, psychological distress, and premature death relative to breast cancer survivors without diabetes. Maintaining glycemic control is critical for decreasing symptoms and preventing serious health problems. Many breast cancer survivors with type 2 diabetes have difficulty maintaining diabetes self-management behaviors and achieving glycemic control. Both cancer and diabetes-related symptoms (e.g., physical symptoms and psychological distress) are often barriers to engaging in diabetes self-management strategies. This study evaluates a novel diabetes coping skills training (DCST) intervention for improving breast cancer survivors' abilities to manage symptoms and adhere to recommended diabetes self-management behaviors. The telephone-based DCST protocol integrates three key theory-based strategies: coping skills training for managing symptoms, adherence skills training, and healthy lifestyle skills training. A randomized clinical trial will test the DCST intervention plus diabetes education by comparing it to diabetes education alone. Symptoms, distress, diabetes self-management behaviors, and self-efficacy will be assessed at baseline and 3, 6, and 12 months. Glycosylated hemoglobin (HbA1c) will be assessed at baseline, 6, and 12 months. This study addresses a critical gap in the care of breast cancer survivors by evaluating a novel behavioral intervention to improve the management of symptoms, adherence, and glycemic control in breast cancer survivors with type 2 diabetes. Special considerations for this medically underserved population are also provided. The findings of this study could lead to significant improvements in clinical care and beneficial outcomes for breast cancer survivors. Trials registration: ClinicalTrials.gov, NCT02970344, registered 11/22/2016.

Physiologic responses to feeding rumen-protected glucose to lactating dairy cows

It was hypothesized that rumen-protected glucose (RPG) in diets of dairy cows increases concentrations of insulin resulting in greater blood progesterone concentrations because elevated insulin decreases activity of liver enzymes inactivating steroid hormones. Timing of ovulation was synchronized among 64 postpartum Holstein cows using GnRH and PGF_2α (Day 0 = ovulation). Cows were milked thrice daily and assigned randomly a basal diet supplemented with 0, 1, 2, or 4 kg of an RPG product in place of corn grain, top-dressed in the diet beginning on Day -3. Blood was collected pre- and post-prandial on Days 0, 2, and 4 to determine plasma glucose and insulin concentrations and daily from Days 2 through 12. Intake of crude protein and energy-soluble carbohydrates increased linearly with dose, whereas starch intake decreased linearly with dose. Neither daily milk yield nor dry matter intake (DMI), energy-corrected milk (ECM), somatic cell count, or percentages of milk fat, protein and lactose on Day 8 differed among dietary treatments. Neither pre- nor post-prandial changes in plasma glucose differed among treatments. In contrast, post-prandial glucose decreased from Days 0 through 4. A change in plasma insulin (post-prandial minus pre-prandial) was detected. Milk urea nitrogen increased linearly with RPG dose. Concentrations of progesterone were unaffected by RPG dose. It is concluded that insulin response to RPG was decreased relative to the control and RPG supplementation linearly increased crude protein intake and milk urea nitrogen with increasing dose, but did not affect concentrations of progesterone, milk yield, or dry matter intake.

The role of insulin in transdifferentiated hepatocyte proliferation and function in serum-free medium

Transdifferentiated hepatocytes are potential seeding cells for bioartificial liver (BAL) treatment, and it is important to obtain a sufficient number of functional hepatocytes in serum-free medium (SFM). Although insulin plays an essential role in promoting cell proliferation and metabolism, the functions of insulin in transdifferentiated cells remain poorly understood. Here, we found that 1.0 mg/L insulin significantly increased human-induced hepatocyte-like cells (hiHeps) proliferation and viability in SFM. The pro-proliferative effect of insulin on these cells occurred via augmented cyclin D1 expression that was mediated by activation of the Akt1/mTOR/p70S6K and Akt1/P53 pathways. Further studies revealed that insulin also enhanced the specific liver function of hiHeps in SFM. Additionally, Western blotting and siHNF1A transfection analysis showed that insulin increased the protein expression of Albumin (ALB) and UDP-glucuronosyltransferase1A1 （UGT1A1 ） in hiHeps via HNF1A. Finally, hiHep proliferation and the expression of specific genes were maintained during long-term passaging in SFM supplemented with 1.0 mg/L insulin. Collectively, our findings show that insulin promotes transdifferentiated hiHep proliferation and specific functional expression. These findings have important implications for the expansion of functional hiHeps prior to clinical applications of BALs.

Stimulating effect of palmitate and insulin on cell migration and proliferation in PNT1A and PC3 prostate cells: Counteracting role of metformin

BACKGROUND

A potential association between obesity and prostate cancer has been proposed. Metformin, an antidiabetes drug, has antiproliferative effects being proposed for cancer treatment. However, under intense proliferative stimulation conditions such as those found in obesity, its efficacy is still uncertain. Thus, we analyzed the effects of saturated fatty acid and/or insulin under high concentrations, with or without metformin, on the proliferation and migration of prostate cells.

METHODS

Human prostate epithelial cell lines non-tumor (PNT1A) and tumor (PC3) were treated with control media (DMEM, C), palmitate (100 µM, HF), and/or insulin (50 µU, HI) with or without metformin (100 µM) for 24 or 48 h.

RESULTS

Both PNT1A and PC3 cells had greater proliferation when treated with HF, while HI treatment stimulated only PNT1A. Metformin inhibited cell proliferation caused by HF in both cell lines, but it did not block the proliferative action of HI in PNT1A cells. PNT1A increased cell migration after all treatments, while only HF influenced PC3; metformin inhibited the migration stimulated by all obese microenvironments. Both HF and HI treatments in PNT1A and HF treatment in PC3 augmented vimentin expression, resulting in a higher epithelial-mesenchymal transition (which, in turn, could influence cell migration). Metformin inhibited vimentin expression in both normal and tumor cells. Although HF treatment had increased AMPK activation, it also increased the levels of activated ERK1/2, which could be responsible for high cell proliferation in both cell lines. In contrast, HI decreased AMPK activation in both cell lines, whereas it increased ERK1/2 levels in PNT1A and decreased them in PC3 (reflecting greater cell proliferation only in non-tumor cells). Metformin maintained high activation of AMPK and decreased ERK1/2 levels after HF in both cell lines and only after HI in PNT1A, which was able to decrease the cell proliferation triggered by these treatments.

CONCLUSIONS

Higher concentrations of palmitate on PC3 cells and palmitate and insulin on PNT1A cells stimulate cellular activities that could favor cancer progression. Metformin inhibited most of these stimuli, showing the efficacy of this drug for cancer adjuvant therapy in obese patients (a group at increased risk for the development of prostrate cancer).

Long-acting insulin analogs and cancer

AIMS

Hyperinsulinemia is a recognized risk factor for cancer and plays a major role for the increased cancer incidence in diabetic patients. Whether insulin analogs, and particularly long-acting analogs, worsen the pro-cancer effect of excess insulin is still controversial.

DATA SYNTHESIS

In this paper we summarize the biological bases for the potential detrimental effect of long-acting analogs on cancer cells and review the in vitro and in vivo evidence on this issue. Because of their different molecular structure relative to native insulin, insulin analogs may activate the insulin receptor (IR) and the post receptor pathways differently. Most, but not all, in vitro evidence indicate that long-acting analogs may have a stronger mitogenic potency than insulin on cancer cells. Notably insulin glargine, the most studied long-acting analog, also has a higher affinity for the insulin-like growth factor (IGF)-1 receptor, a potent growth mediator. In vitro observations, however, may not reflect what occurs in vivo when analogs are metabolized to derivatives with a different mitogenic activity. Clinical studies, mostly retrospective and predominantly concerning glargine, provide contrasting results. The only perspective trial found no cancer increase in patients treated with glargine. All these studies, however, have severe weaknesses because of the insufficient evaluation of important factors such as dose administered, length of exposure, patient follow-up duration and site-specific cancer investigation. Moreover, whether cancer promotion is a long-acting analog class characteristic or a specific effect of a single agent is not clear.

CONCLUSIONS

In conclusion the carcinogenic risk of long-acting analogs, and specifically glargine, can be neither confirmed nor excluded. A personalized and shared decision, considering all the individual risk factors (metabolic and non-metabolic), is the suggestion for the clinician.

The association of diabetes mellitus and insulin treatment with expression of insulin-related proteins in breast tumors

BACKGROUND

The insulin receptor (INSR) and the insulin growth factor 1 receptor (IGF1R) play important roles in the etiology of both diabetes mellitus and breast cancer. We aimed to evaluate the expression of hormone and insulin-related proteins within or related to the PI3K and MAPK pathway in breast tumors of women with or without diabetes mellitus, treated with or without insulin (analogues).

METHODS

Immunohistochemistry was performed on tumor tissue of 312 women with invasive breast cancer, with or without pre-existing diabetes mellitus, diagnosed in 2000-2010, who were randomly selected from a Danish breast cancer cohort. Women with diabetes were 2:1 frequency matched by year of birth and age at breast cancer diagnosis to those without diabetes. Tumor Microarrays were successfully stained for p-ER, EGFR, p-ERK1/2, p-mTOR, and IGF1R, and scored by a breast pathologist. Associations of expression of these proteins with diabetes, insulin treatment (human insulin and insulin analogues) and other diabetes medication were evaluated by multivariable logistic regression adjusting for menopause and BMI; effect modification by menopausal status, BMI, and ER status was assessed using interactions terms.

RESULTS

We found no significant differences in expression of any of the proteins in breast tumors of women with (n = 211) and without diabetes (n = 101). Among women with diabetes, insulin use (n = 53) was significantly associated with higher tumor protein expression of IGF1R (OR = 2.36; 95%CI:1.02-5.52; p = 0.04) and p-mTOR (OR = 2.35; 95%CI:1.13-4.88; p = 0.02), especially among women treated with insulin analogues. Menopause seemed to modified the association between insulin and IGF1R expression (p = 0.07); the difference in IGF1R expression was only observed in tumors of premenopausal women (OR = 5.10; 95%CI:1.36-19.14; p = 0.02). We found no associations between other types of diabetes medication, such as metformin, and protein expression of the five proteins evaluated.

CONCLUSIONS

In our study, breast tumors of women with pre-existing diabetes did not show an altered expression of selected PI3K/MAPK pathway-related proteins. We observed an association between insulin treatment and increased p-mTOR and IGF1R expression of breast tumors, especially in premenopausal women. This observation, if confirmed, might be clinically relevant since the use of IGF1R and mTOR inhibitors are currently investigated in clinical trials.

Genome-Wide Analyses Identify Filamin-A As a Novel Downstream Target for Insulin and IGF1 Action

Insulin analogs were developed to improve diabetes therapy. However, certain modifications introduced into the insulin molecule were shown to enhance their affinity to the insulin-like growth factor-1 receptor (IGF1R). Most tumors, including endometrial cancers, express high levels of IGF1R. The present study was aimed at identifying the entire set of genes that are differentially activated by insulin glargine or detemir, in comparison to insulin and IGF1, in Type 1 and Type 2 endometrial cancer cell lines (ECC-1 and USPC-1, respectively). Global gene expression analyses demonstrated a ligand-dependent upregulated expression of filamin-A (FLNA), a gene that encodes an actin filament cross-linking protein, in both endometrial cancer cell types. Silencing experiments linked to migration assays confirmed the role of FLNA in cell growth and motility. Our data suggest that the activation of distinct sets of genes by glargine may lead to stimulation of specific pathways or, alternatively, may provide additive effects, different from those classically induced by insulin. Given that metastases are probably the main factor contributing to tumor invasiveness, the identification of FLNA as a downstream target for insulin-like hormones may be of translational relevance in oncology. Clinical studies in endometrial cancer may add further relevant information regarding the possible differential actions of insulin analogs with respect to native insulin.

Effects of insulin analogs and glucagon-like peptide-1 receptor agonists on proliferation and cellular energy metabolism in papillary thyroid cancer

Purpose

This study was aimed to investigate the expressions of the insulin receptor (IR), insulin-like growth factor receptor (IGF-1R), and glucagon-like peptide-1 receptor (GLP-1R) in normal thyroid tissue, papillary thyroid cancer (PTC) tissues, and PTC cells, and to examine the possible role of insulin analogs and GLP-1R agonists in cell proliferation and energy metabolism in PTC cells.

Methods

The expressions of IR, IGF-1R, and GLP-1R in PTC tissues and PTC cell lines were detected by immunohistochemistry and western blotting, respectively. Cell proliferation was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Levels of members of the phosphoinositol-3 kinase/AKT serine/threonine kinase (Akt) and mitogen-activated protein kinase/extracellular signal-regulated kinase (Erk) signaling pathways were measured by western blotting. Energy metabolism of PTC cell lines was analyzed using a Seahorse Extracellular Flux analyzer.

Results

Three receptors could be detected in both PTC tissues and PTC cell lines. Expressions of IGF-1R and GLP-1R were more obvious in PTC than in normal thyroid cells. Neither insulin, four insulin analogs, and two GLP-1R agonists showed significant effects on the proliferation of PTC cells, nor did they influence the levels of Akt/p-Akt and Erk/p-Erk. None of these antidiabetic agents could change the mitochondrial respiration and glycolysis levels in PTC cell lines.

Conclusion

Both PTC tissues and the PTC cell lines express IR, IGF-1R, and GLP-1R. However, insulin analogs and GLP-1R agonists, which are commonly used to treat patients with diabetes, may not influence cell proliferation, the phosphoinositol-3 kinase/Akt and mitogen-activated protein kinase/Erk pathways, or energy metabolism in PTC cells. For now, it is not necessary to avoid use of these antidiabetic agents in patients with PTC.

Insulin Receptor Isoforms in Physiology and Disease: An Updated View

The insulin receptor (IR) gene undergoes differential splicing that generates two IR isoforms, IR-A and IR-B. The physiological roles of IR isoforms are incompletely understood and appear to be determined by their different binding affinities for insulin-like growth factors (IGFs), particularly for IGF-2. Predominant roles of IR-A in prenatal growth and development and of IR-B in metabolic regulation are well established. However, emerging evidence indicates that the differential expression of IR isoforms may also help explain the diversification of insulin and IGF signaling and actions in various organs and tissues by involving not only different ligand-binding affinities but also different membrane partitioning and trafficking and possibly different abilities to interact with a variety of molecular partners. Of note, dysregulation of the IR-A/IR-B ratio is associated with insulin resistance, aging, and increased proliferative activity of normal and neoplastic tissues and appears to sustain detrimental effects. This review discusses novel information that has generated remarkable progress in our understanding of the physiology of IR isoforms and their role in disease. We also focus on novel IR ligands and modulators that should now be considered as an important strategy for better and safer treatment of diabetes and cancer and possibly other IR-related diseases.

Exosome miR-371b-5p promotes proliferation of lung alveolar progenitor type II cells by using PTEN to orchestrate the PI3K/Akt signaling

Background

Pathways directing endogenous stem/progenitor cells to restore normal architecture and function of damaged/diseased lungs remain underexplored. Published data have revealed that alveolar progenitor type II cell (ATIIC)-derived signaling promotes re-epithelialization of injured alveoli, yet the underlying mechanism is unknown. Here we aim to define the role of ATIIC-derived exosome miRNA signaling in controlling ATIIC-specific proliferation or differentiation in response to injury.

Methods

Pluripotent stem cell-derived cultures, which contain early lung stem/progenitor populations that can subsequently differentiate into ATIICs, were used as a model for unbiased screening and identification of ATIIC phenotype-specific exosome miRNA signaling, and human induced pluripotent stem cell-derived ATIICs (hiPSC-ATIICs) were employed to examine the molecular basis of key exosome miRNA signaling in promoting ATIIC-specific proliferation. QRT-PCR was performed to examine expression pattern of ATIIC-derived key exosome miRNA in an alveolar injury model and in injured human lungs.

Results

We show that human ATIIC line (A549)-derived exosome miR-371b-5p promotes ATIIC-specific proliferation, but not differentiation, in differentiating cultures of pluripotent stem cells. Using 3′UTR-driven luciferase reporters, we identified PTEN as a direct target of miR-371b-5p. Transfection of miR-371b-5p mimic into hiPSC-ATIICs leads to significantly decreased expression of endogenous PTEN, which stimulates phosphorylation of Akt and its downstream substrates, GSK3β and FOXOs, promoting cell proliferation. While not expressed in normal ATIIC phenotypes, the exosome miR-371b-5p expression is significantly induced after hiPSC-ATIICs or hATIICs (human primary ATIICs) are subjected to bleomycin-induced injury. To rule out that the ATIIC-derived exosome-miRNAs are merely a cell culture phenomenon, we transplanted hiPSC-ATIICs into bleomycin-challenged lungs of mice, and found that the transplanted hiPSC-ATIICs engraft and express exosome miR-371b-5p, along with additional survival of numerous mouse ATIICs in bleomycin-injured lungs. Consistent with these findings, significant levels of exosome miR-371b-5p were also detected in lavage samples of patients with acute pneumonia, but not in those from patients without pulmonary disorders.

Conclusions

Collectively, our data strongly suggest that ATIIC-derived exosome miR-371b-5p may serve as a niche signaling to augment ATIIC survival/proliferation, promoting re-epithelialization of injured alveoli, and thus provide a promising novel target to develop treatment for currently incurable lung diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0586-2) contains supplementary material, which is available to authorized users.

Therapeutic molecules against type 2 diabetes: What we have and what are we expecting?

World Health Organization (WHO) has identified diabetes as one of the fastest growing non-communicable diseases with 422 million patients around the world in 2014. Diabetes, a metabolic disease, is characterized primarily by hyperglycemia which results in various macrovascular and microvascular complications like cardiovascular disease and neuropathies which can significantly deteriorate the quality of life. The body either does not manufactures enough insulin (type 1 diabetes or T1DM) or becomes insensitive to physiologically secreted insulin or both (type 2 diabetes or T2DM). The majority of the diabetic population is affected by type 2 diabetes. Currently, hyperglycemia is treated by a broad range of molecules such as biguanides, sulfonylurea, insulin, thiazolidinediones, incretin mimetics, and DPP-4 inhibitors exerting different mechanisms. However, new drug classes have indeed come in the market such as SGLT-2 inhibitors and other are in the experimental stages such as GPR 40 agonists, GSK-3 inhibitors, GK activators and GPR21 inhibitors which definitely could be anticipated as safe and effective for diabetes therapy. This article reviews the general approach to currently approved therapies for type 2 diabetes and focusing on novel approaches that could be a panacea and might be useful in the future for diabetes patients.

Prevention of tumour cell apoptosis associated with sustained protein kinase B phosphorylation is more sensitive to regulation by insulin signalling than stimulation of proliferation and extracellular signal-regulated kinase

Insulin controls blood glucose while insulin-like growth factor (IGF) 1 is an important growth factor. Interestingly, both hormones have overlapping bioactivities and can activate the same intracellular signal transduction cascades. Growth control (mainly by IGF1) and metabolic function (predominantly by insulin) are believed to depend on activation of extracellular signal-regulated kinases (ERKs) 1/2 and protein kinase B (Akt/PKB), respectively. Therefore, insulin analogues that are used to normalize blood glucose are tested for their ability to preferentially activate Akt/PKB but not ERK1/2 and mitogenesis. Growth hormone, IGF1, and hyperinsulinemia are associated with increased risk of growth progression of some cancer types. To test if continuous exposure to insulin can favour tumour growth, we studied insulin/IGF1-dependent activation of ERK1/2 and Akt/PKB by Western blotting, inhibition of apoptosis by ELISA, and induction of proliferation by [³H]-thymidine incorporation in Saos-2/B10 osteosarcoma cells. IGF1 and insulin both induced proliferation and prevented apoptosis effectively. Regulation of apoptosis was far more sensitive than regulation of proliferation. IGF1 and insulin activated PKB (Akt/PKB) rapidly and consistently maintained its phosphorylation. Activation of ERK1/2 was only observed in response to IGF1. Loss of p-Akt/PKB (but not of p-ERK1/2) was associated with increased apoptosis, and protection from apoptosis was lost when activation of Akt/PKB was inhibited. These findings in Saos-2/B10 cells were also replicated in the A549 cell line, originally derived from a human lung carcinoma. Therefore, IGF1 and insulin more likely (at lower concentrations) enhance tumour cell survival than proliferation, via activation and maintenance of phosphatidylinositol 3-kinase activity and p-Akt/PKB.

Type 2 diabetes, insulin treatment and prognosis of breast cancer

BACKGROUND

The aim of our study was to investigate whether pre-existing type 2 diabetes and insulin therapy have an impact on the prognosis of breast cancer patients.

METHODS

We performed a retrospective analysis of 462 type 2 diabetic breast cancer patients and 1644 non-diabetic breast cancer patients treated in our institute from January 2005 to August 2010. Patients were divided by diabetes status and insulin use. The clinicopathological characteristics and clinical outcomes of patients within 5 years following breast cancer diagnosed were analysed.

RESULTS

Diabetic patients tended to have higher body mass index and higher histological grade tumours. Five-year disease-free survival and overall survival were reduced in diabetic patients (P < 0.001), and diabetes was an independent predictor for an increased risk of breast cancer relapse and death within 5 years (P < 0.001). Insulin treatment was associated with reduced 5-year disease-free survival and overall survival (P < 0.05); the risk of 5-year relapse and breast cancer mortality in the insulin group increased compared to that of non-insulin group after adjusting for age, tumour size, histological grade, oestrogen receptor, progesterone receptor, chemotherapy and hormone therapy (P < 0.05). After adjusting for age and other factors, the risk of breast cancer relapse was also increased in the insulin subgroup, while the risk of breast cancer mortality did not increase statistically.

CONCLUSIONS

Type 2 diabetes and insulin treatment might be independently associated with poorer prognosis of breast cancer. However, caution is needed when interpreting our results, and further investigations are needed. Copyright © 2016 John Wiley & Sons, Ltd.

Insulin Promotes the Proliferation of Human Umbilical Cord Matrix-Derived Mesenchymal Stem Cells by Activating the Akt-Cyclin D1 Axis

Background. The functions of insulin in mesenchymal stem cells (MSC) remain poorly understood. Methods. MSC from human umbilical cord matrix (UCM) cultured in serum-free media (SFM) with or without insulin were subjected to various molecular biological analyses to determine their proliferation and growth states, expression levels of Akt-cyclin D1 signaling molecules, and in vitro differentiation capacities. Results. Insulin accelerated the G1-S cell cycle progression of UCM-MSC and significantly stimulated their proliferation and growth in SFM. The pro-proliferative action of insulin was associated with augmented cyclin D1 and phosphorylated Akt expression levels. Akt inactivation remarkably abrogated insulin-induced increases in cyclin D1 expression and cell proliferation, indicating that insulin enhances the proliferation of UCM-MSC via acceleration of the G1-S transition mediated by the Akt-cyclin D1 pathway. Additionally, the UCM-MSC propagated in SFM supplemented with insulin exhibited similar specific surface antigen profiles and differentiation capacities as those generated in conventional media containing fetal bovine serum. Conclusions. These findings suggest that insulin acts solely to promote UCM-MSC proliferation without affecting their immunophenotype and differentiation potentials and thus have important implications for utilizing insulin to expand clinical-grade MSC in vitro.

Treatment with insulin analogs, especially Glargine and Lispro, associates with better renal function and higher hemoglobin levels in Type 1 diabetic patients with impaired kidney function

OBJECTIVES

The influence of type of insulin treatment - insulin analogs versus human insulin - on the development of diabetes related vascular complications has been sparsely investigated. We examine here possible differences regarding kidney function and hemoglobin levels.

METHODS

Multiple linear regression was used to investigate the relationship between the following characteristics measured in 509 type 1 diabetic patients who were recruited in an outpatient practice: current clinical status and treatment modalities, type of injected insulin and the routine laboratory parameters hemoglobin, HbA1c, serum creatinine, eGFR, hs CRP and urinary albumin/creatinine ratio.

RESULTS

Compared with human insulin, multiple regression analysis taking into account possible confounders revealed that treatment with insulin analogs was associated with increased eGFR (+7.1 ml/min; P=0.0002), lower urinary albumin/creatinine ratio (ratio logarithm -0.4; P=0.003) and higher hemoglobin concentration (+0.31 g/dl; P=0.04). Stratification by type of insulin showed the best renal status for treatment with insulins Glargine and Lispro. Differences were consistent both for patients with normal (eGFR → 90 ml/min) and with an impaired (eGFR ← 90 ml/min) kidney function.

CONCLUSIONS

Present results suggest that treatment of type 1 diabetic patients with normal and impaired renal function with insulin analogs, especially Glargine and Lispro, is associated with better kidney function, lower urinary albumin/creatinine ratio and lower hemoglobin concentration compared to therapy with human insulin. If confirmed by other studies, treatment with insulin analogs may be a further possibility in delaying progression of nephropathy and in preventing early hemoglobin decline.

Effects of insulin on peripheral nerves

AIMS

To assess the effects of insulin on peripheral nerve under normoglycemic and hyperglycemic conditions in the presence and absence of anoxia.

METHODS

This study uses the in-vitro sciatic nerve model to assess the effect of insulin on peripheral nerve with the nerve action potential (NAP) as an index of nerve function.

RESULTS

Under normoglycemic conditions, low concentrations of regular insulin (0.01nM) reduced the conduction velocity of oxygenated nerves. Hyperglycemia increased the duration of the NAP and this increase was nearly completely eliminated by insulin in the 0.1nM-100nM concentration range. Insulin (1nM) also had effects on normoglycemic nerves exposed to intermittent anoxia, producing a decrease in the paired-pulse response and NAP amplitude and an increase in peak duration. This was associated with a reduced time to anoxia-induced conduction block. Similar effects were seen when regular insulin was replaced by insulin detemir, but the latter required much higher concentrations.

CONCLUSIONS

Insulin has concentration dependent effects on the peripheral nerve that are dependent on glucose and anoxia. These effects may be important in modulating neuropathic consequences of diabetes.

Diabetes-associated dysregulated cytokines and cancer

Epidemiological data demonstrate that patients with diabetes have an augmented risk of developing various types of cancers, accompanied by higher mortality. A number of mechanisms for this connection have been hypothesized, such as insulin resistance, hyperinsulinemia, hyperglycemia, and increased inflammatory processes. Apart from these potential mechanisms, several diabetes-associated dysregulated cytokines might be implicated in the link between diabetes and cancer. In fact, some inflammatory cytokines, e.g. TNF-α, IL-6 and leptin, have been revealed to play important roles in both initiation and progression of tumor. Here, we depict the role of these cytokines in key events of carcinogenesis and cancer development, including their capability to induce oxidative stress, inflammation, their participation in epithelial mesenchymal transition (EMT), angiogenesis, and metastasis. Finally, we will also highlight the existing knowledge in terms of the involvement of these cytokines in different cancer types and comment on potential significances for future clinical applications.

Effect of insulin analogues on phosphatidyl inositol-3 kinase/Akt signalling in INS-1 rat pancreatic derived β-cells

CONTEXT

Insulin analogues are largely used for the treatment of diabetic patients, but concerns have been raised about their mitogenic/anti-apoptotic potential. It is therefore important to evaluate these analogues in different cell systems.

OBJECTIVE

The aim of this work was to establish the pharmacological profiles of insulin analogues towards PI-3 kinase/Akt pathway in INS-1 β-pancreatic cells.

METHODS

Bioluminescence Resonance Energy Transfer (BRET), in cell western and caspase 3/7 assays, was used to study the effects of ligands.

RESULTS

Among the five analogues evaluated, only glargine stimulated PI-3 kinase/Akt pathway with higher efficiency than insulin, whereas glargine's metabolite M1 was less efficient. However, glargine did not show higher anti-apoptotic efficiency than insulin.

CONCLUSION

Glargine was more efficient than insulin for the activation of PI-3 kinase/Akt pathway, but not for the inhibition of caspase 3/7 activity. Moreover, glargine's metabolite M1 displayed lower efficiency than insulin towards PI-3 kinase/Akt activation and caspase 3/7 inhibition.

Agonistic aptamer to the insulin receptor leads to biased signaling and functional selectivity through allosteric modulation

Due to their high affinity and specificity, aptamers have been widely used as effective inhibitors in clinical applications. However, the ability to activate protein function through aptamer-protein interaction has not been well-elucidated. To investigate their potential as target-specific agonists, we used SELEX to generate aptamers to the insulin receptor (IR) and identified an agonistic aptamer named IR-A48 that specifically binds to IR, but not to IGF-1 receptor. Despite its capacity to stimulate IR autophosphorylation, similar to insulin, we found that IR-A48 not only binds to an allosteric site distinct from the insulin binding site, but also preferentially induces Y1150 phosphorylation in the IR kinase domain. Moreover, Y1150-biased phosphorylation induced by IR-A48 selectively activates specific signaling pathways downstream of IR. In contrast to insulin-mediated activation of IR, IR-A48 binding has little effect on the MAPK pathway and proliferation of cancer cells. Instead, AKT S473 phosphorylation is highly stimulated by IR-A48, resulting in increased glucose uptake both in vitro and in vivo. Here, we present IR-A48 as a biased agonist able to selectively induce the metabolic activity of IR through allosteric binding. Furthermore, our study also suggests that aptamers can be a promising tool for developing artificial biased agonists to targeted receptors.

Treatment with insulin (analogues) and breast cancer risk in diabetics; a systematic review and meta-analysis of in vitro, animal and human evidence

INTRODUCTION

Several studies have suggested that anti-diabetic insulin analogue treatment might increase cancer risk. The aim of this study was to review the postulated association between insulin and insulin analogue treatment and breast cancer development, and plausible mechanisms.

METHOD

A systematic literature search was performed on breast cell-line, animal and human studies using the key words 'insulin analogue' and 'breast neoplasia' in MEDLINE at PubMed, EMBASE, and ISI Web of Science databases. A quantitative and qualitative review was performed on the epidemiological data; due to a limited number of reported estimates, a meta-analysis was performed for glargine only. A comprehensive overview was composed for in vitro and animal studies. Protein and gene expression was analysed for the cell lines most frequently used in the included in vitro studies.

RESULTS

In total 16 in vitro, 5 animal, 2 in vivo human and 29 epidemiological papers were included. Insulin AspB10 showed mitogenic properties in vitro and in animal studies. Glargine was the only clinically available insulin analogue for which an increased proliferative potential was found in breast cancer cell lines. However, the pooled analysis of 13 epidemiological studies did not show evidence for an association between insulin glargine treatment and an increased breast cancer risk (HR 1.04; 95 % CI 0.91-1.17; p=0.49) versus no glargine in patients with diabetes mellitus. It has to be taken into account that the number of animal studies was limited, and epidemiological studies were underpowered and suffered from methodological limitations.

CONCLUSION

There is no compelling evidence that any clinically available insulin analogue (Aspart, Determir, Glargine, Glulisine or Lispro), nor human insulin increases breast cancer risk. Overall, the data suggests that insulin treatment is not involved in breast tumour initiation, but might induce breast tumour progression by up regulating mitogenic signalling pathways.

Non-small cell lung cancer cell survival crucially depends on functional insulin receptors

Insulin plays an important role as a growth factor and its contribution to tumor proliferation is intensely discussed. It acts via the cognate insulin receptor (IR) but can also activate the IGF1 receptor (IGF1R). Apart from increasing proliferation, insulin might have additional effects in lung cancer. Therefore, we investigated insulin action and effects of IR knockdown (KD) in three (NCI-H292, NCI-H226 and NCI-H460) independent non-small cell lung cancer (NSCLC) cell lines. All lung cancer lines studied were found to express IR, albeit with marked differences in the ratio of the two variants IR-A and IR-B. Insulin activated the classical signaling pathway with IR autophosphorylation and Akt phosphorylation. Moreover, activation of MAPK was observed in H292 cells, accompanied by enhanced proliferation. Lentiviral shRNA IR KD caused strong decrease in survival of all three lines, indicating that the effects of insulin in lung cancer go beyond enhancing proliferation. Unspecific effects were ruled out by employing further shRNAs and different insulin-responsive cells (human pre-adipocytes) for comparison. Caspase assays demonstrated that IR KD strongly induced apoptosis in these lung cancer cells, providing the physiological basis of the rapid cell loss. In search for the underlying mechanism, we analyzed alterations in the gene expression profile in response to IR KD. A strong induction of certain cytokines (e.g. IL20 and tumour necrosis factor) became obvious and it turned out that these cytokines trigger apoptosis in the NSCLC cells tested. This indicates a novel role of IR in tumor cell survival via suppression of pro-apoptotic cytokines.

Proliferative and signaling activities of insulin analogues in endometrial cancer cells

Insulin analogues have been developed to achieve further improvement in the therapy of diabetes. However, modifications introduced into the insulin molecule may enhance their affinity for the insulin-like growth factor-1 receptor (IGF1R). Hyperinsulinemia has been identified as a risk factor for endometrial cancer. We hypothesized that insulin analogues may elicit atypical proliferative and signaling activities in endometrial cancer cells. Our results demonstrate that glargine, but not detemir, stimulated cell proliferation, displayed an anti-apoptotic effect, and had a positive effect on cell cycle progression in endometrial cancer cell lines ECC-1 and USPC-1. In addition, we showed that glargine and detemir induced dual activation of the insulin receptor (INSR) and IGF1R in both cell types. Furthermore, we showed that glargine elicited signaling events that are markedly different from those induced by insulin. In conclusion, our data support the concept that, although insulin analogues were designed to display insulin-like metabolic effects, glargine and, possibly, additional analogues exhibit IGF1-like activities and, accordingly, may function as IGF1 analogues.

Antihyperglycaemic therapies and cancer risk

AIMS

This review is aimed at highlighting the potential mitogenic/tumour growth-promoting or antimitogenic/tumour growth-inhibiting effects of the main antihyperglycaemic drug classes.

METHODS

We review and discuss the most current studies evaluating the association between antidiabetic medications used in clinical practice and malignancies as described so far.

RESULTS

Metformin seems to be the only antidiabetic drug to exert protective effects both on monotherapy and also when combined with other oral antidiabetic drugs or insulins in several site-specific cancers. In contrast, several other drug classes may increase cancer risk. Some reason for concern remains regarding sulphonylureas and also the incretin-based therapies regarding pancreas and thyroid cancers and the sodium glucose cotransporter-2 inhibitors as well as pioglitazone regarding bladder cancer. The majority of meta-analyses suggest that there is no evidence for a causal relationship between insulin glargine and elevated cancer risk, although the studies have been controversially discussed. For α-glucosidase inhibitors and glinides, neutral or only few data upon cancer risk exist.

CONCLUSION

Although the molecular mechanisms are not fully understood, a potential risk of mitogenicity and tumour growth promotion cannot be excluded in case of several antidiabetic drug classes. However, more large-scale, randomized, well-designed clinical studies with especially long follow-up time periods are needed to get reliable answers to these safety issues.

Pharmacological overview of galactogogues

Galactogogues are substances used to induce, maintain, and increase milk production, both in human clinical conditions (like noninfectious agalactias and hypogalactias) and in massification of production in the animal dairy industry. This paper aims to report the state of the art on the possible mechanisms of action, effectiveness, and side effects of galactogogues, including potential uses in veterinary and human medicine. The knowledge gaps in veterinary clinical practice use of galactogogues, especially in the standardization of the lactogenic dose in some pure drugs and herbal preparations, are reviewed.

Glargine metabolism over 24 h following its subcutaneous injection in patients with type 2 diabetes mellitus: a dose-response study

BACKGROUND AND AIMS

After subcutaneous injection insulin glargine is rapidly metabolized to M1 and M2. In vitro, both M1 and M2 have metabolic effects and bind to IGF-1R similarly to human insulin, whereas glargine exhibits a higher affinity for the IGF-1R and greater mitogenetic effects. The present study was specifically designed to establish the dose-response metabolism of glargine over 24 h following s.c. injection in T2DM subjects on long-term use of glargine.

METHODS AND RESULTS

Ten subjects with T2DM were studied during 24 h after s.c. injection of 0.4 (therapeutic) and 0.8 (high dose) U/kg of glargine on two separate occasions during euglycaemic clamps (cross-over design). Glargine, M1 and M2 over 24 h period were determined in appropriately processed plasma samples by a specific liquid chromatography-tandem mass spectrometry assay. Plasma M1 concentration (AUC0-24 h) was detected in all subjects and increased by increasing the glargine dose from therapeutic to high dose (p = 0.008). Glargine was detectable in 6 (therapeutic dose) and 9 (high dose) out of the 10 subjects and also increased by increasing the dose (p = 0.031). However, glargine concentration (AUC0-24 h--high dose) represented at most only 9.7% (4.6-15%) of the total amount of insulin measured in the blood. M2 was not detected at all.

CONCLUSION

In T2DM people on long-term use of insulin glargine, even with higher doses (0.8 U/kg), glargine is nearly totally metabolized to the active metabolite M1. Glargine is often detectable in plasma, but its concentration remains well below that needed in vitro to potentiate IGF-1R binding and mitogenesis.

14-Year risk of all-cause mortality according to hypoglycaemic drug exposure in a general population

Purpose

Guidelines for management of patients with type 2 diabetes mellitus recommend the use of hypoglycaemic drugs when lifestyle interventions remain insufficient for glycaemic control. Recent trials have provided worrying safety data on certain hypoglycaemic drugs. The aim of this study was to assess 14-year risk of all-cause mortality according to hypoglycaemic drug exposure at baseline, in a general population.

Methods

Our analysis was based on the observational Third French MONICA survey on cardiovascular risk factors (1995–1997). Vital status was obtained 14 years after inclusion, and assessment of determinants of mortality was based on multivariable Cox modelling.

Results

There were 3336 participants and 248 deaths over the 14-year period. At baseline, there were 3162 (95%) non-diabetic, 46 (1%) untreated type 2 diabetic and 128 (4%) type 2 diabetic subjects with hypoglycaemic drug treatment (metformin alone (31%), sulfonylureas alone or in combination (49%), insulin alone or in combination (10%), or other treatments (9%)). After adjustment for duration of diabetes, history of diabetes complications, area of residence (centre), age, gender, educational level, alcohol consumption, smoking, blood pressure, LDL and HDL cholesterol, which all were significant and independent determinants of mortality, the hazard ratio for all-cause mortality was 3.22 [95% confidence interval: 0.87–11.9] for untreated diabetic subjects, 2.28 [0.98–5.26] for diabetics treated with metformin alone, 1.70 [0.92–3.16] for diabetics with sulfonylureas and 4.92 [1.70–14.3] for diabetic with insulin versus non-diabetic subjects.

Conclusions

Our results support the conclusion that until more evidence is provided from randomized trials, a prudent approach should be to restrain use of insulin to situations in which combinations of non-insulin agents have failed to appropriately achieve glycemic control, as it is recommended in the current guidelines for the management of type 2 diabetes.

Classifying the adverse mitogenic mode of action of insulin analogues using a novel mechanism-based genetically engineered human breast cancer cell panel

Insulin analogues are widely used in clinical practice. Modifications on the insulin molecular structure can affect the affinity and activation towards two closely related receptor tyrosine kinases: the insulin receptor (INSR) and the insulin-like growth factor 1 receptor (IGF1R). A switch towards higher IGF1R affinity is likely to emphasize mitogenesis rather than glucose metabolism. Relevant well-validated experimental tools to address the insulin analogue activation of either INSR or IGF1R are missing. We have established a panel of human MCF-7 breast cancer cell lines either ectopically expressing the INSR (A or B isoform) in conjunction with a stable knockdown of the IGF1R or ectopically expressing the IGF1R in conjunction with a stable knockdown of the INSR. In these cell lines, we systematically evaluated the INSR and IGF1R receptor activation and downstream mitogenic signalling of all major clinical relevant insulin analogues in comparison with insulin and IGF1R. While most insulin analogues primarily activated the INSR, the mitogenic activation pattern of glargine was highly similar to IGF1 and insulin AspB10, known to bind IGF1R and induce carcinogenesis. Yet, in a long-term proliferation assay, the proliferative effect of glargine was not much different from regular insulin or other insulin analogues. This was caused by the rapid enzymatic conversion into its two metabolic active metabolites M1 and M2, with reduced mitogenic signalling through the IGF1R. In summary, based on our new cell models, we identified a similar mitogenic potency of insulin glargine and AspB10. However, rapid enzymatic conversion of glargine precludes a sustained activation of the IGF1R signalling pathway.

Insulin therapy and risk of prostate cancer: a systematic review and meta-analysis of observational studies

BACKGROUND

Previous observational studies have shown that insulin therapy may modify the risk of prostate cancer (PCa). However, these studies yielded controversial results. Thus, we performed this meta-analysis to determine whether insulin use was associated with PCa risk in patients with diabetes mellitus (DM).

METHOD

A literature search was carried out in PubMed, EMBASE, and Cochrane Library Central database between January 1966 and January 2013. Fixed-effect and random-effect models were used to estimate pooled relative risks (RR) and corresponding 95% confidence intervals (CIs). Subgroup analyses and sensitivity analyses were also performed.

RESULT

A total of 11 (10 cohorts, and one case-control) studies published between 2007 and 2013 were included in the meta-analysis, representing data for 205,523 male subjects and 7,053 PCa cases. There were five studies investigating the influence of insulin and other glucose-lowering agents on the risk of PCa , and six studies investigating the influence of glargine and non-glargine insulin. Insulin use was not associated with PCa risk when compared with other glucose-lowering agents (RR=0.89, 95% CI, 0.72-1.09). Use of insulin glargine did not contribute to susceptibility to PCa as compared with use of non-glargine insulin (RR=1.26, 95% CI, 0.86-1.84). Sensitivity analysis confirmed the stability of present results, since no individual study affected the pooled result significantly.

CONCLUSIONS

Our results suggest that, there may be no significant association between insulin use and risk of PCa as compared with other glucose-lowering agents in patients with DM, and there was no substantial evidence for increase risk of PCa among insulin glargine users as compared to non-glargine insulin users. Further studies are warranted to validate these conclusions.

Clinical and molecular mechanisms favoring cancer initiation and progression in diabetic patients

Cancer incidence and mortality are higher among diabetic patients. This review examines the mechanisms, both general and site-specific, for this increase. Hyperglycemia and hyperinsulinemia, which are the major abnormalities that characterize diabetes, can promote cancer via both independent and synergic mechanisms. Insulin is both a metabolic hormone and a growth factor that promotes cell proliferation. When insulin levels are increased due to either insulin resistance or insulin treatment, their mitogenic effect is more marked in malignant cells that frequently overexpress the insulin receptor and, more specifically, its A isoform that has predominant mitogenic activity. Hyperglycemia provides energy for malignant cell proliferation and, via the peculiar energy utilization of cancer cells, favors cancer growth and neoangiogenesis. Additionally, diabetes-associated obesity has cancer-promoting effects due to mechanisms that are specific to excess fat cells (such as increased peripheral estrogens, increased pro-mitogen cytokines and growth factors). Also fat-associated chronic inflammation can favor cancer via the cell damage caused by reactive oxygen species (ROS) and via the production of inflammatory cytokines and transcription factors that stimulate cancer growth and invasiveness. Finally, the multiple drugs involved in the treatment of diabetes can also play a role. Diabetes-associated comorbidities, tissue-specific inflammation, and organ-specific dysfunctions can explain why the risk of cancer can differ by tissue type among diabetic patients. The increased risk of cancer-related mortality is moderate among individual patients with diabetes (RR = 1.25), but the pandemic nature of the disease means that a considerable number of lives could be spared through a better understanding of the factors associating diabetes and cancer.

Differences in metabolic and mitogenic signallingof insulin glargine and AspB10 human insulin in rats [corrected]

AIMS/HYPOTHESIS

In vitro, insulin glargine (A21Gly,B31Arg,B32Arg human insulin) has an insulin receptor (IR) profile similar to that of human insulin, but a slightly higher affinity for the IGF-1 receptor (IGF1R). AspB10 human insulin (AspB10), [corrected] the only insulin analogue with proven carcinogenic activity, has a greater affinity for IGF1R and IR, and a prolonged IR occupancy time. The pharmacological and signalling profile of therapeutic and suprapharmacological doses of glargine were analysed in different tissues of rats, and compared with human insulin and AspB10.

METHODS

Male Wistar rats were injected s.c. with human insulin or insulin analogue at doses of 1 to 200 U/kg, and the effects on blood glucose and the phosphorylation status of IR, IGF1R, Akt and extracellular signal-regulated protein kinase 1/2 in muscle, fat, liver and heart samples were investigated.

RESULTS

Glargine, AspB10 and human insulin lowered blood glucose, with the onset of action delayed with glargine. Glargine treatment resulted in phosphorylation levels of IR and Akt that were comparable with those achieved with human insulin, although delayed in time in some tissues. AspB10 treatment resulted in at least twofold higher phosphorylation levels and significantly longer duration of IR and Akt phosphorylation in most tissues. None of the insulin treatments resulted in detectable IGF1R phosphorylation in muscle or heart tissue, whereas intravenous injection of IGF-1 increased IGF1R phosphorylation.

CONCLUSIONS/INTERPRETATION

The IR signalling pattern of AspB10 in vivo is distinctly different from that of human insulin and insulin glargine, and might challenge the notion that activation of IGF1R plays a role in the observed carcinogenic effect of AspB10.

Eph receptor B4 is a regulator of estrogen receptor alpha in breast cancer cells

BACKGROUND

Estrogen receptor alpha (ER-α) plays an important role in breast cancer initiation and progression and represents a major target in cancer therapy. The expression and activity of ER-α is regulated by multiple mechanisms at the transcriptional and post-translational level. Interaction of tyrosine kinase receptor-activated signaling pathways with ER-α function has been reported. We previously performed a kinome-wide small interfering RNA high-throughput screen to identify novel protein kinases involved in the regulation of ER-α transcriptional activity in human breast cancer cells. Our screening analysis identified the Eph receptor tyrosine kinases (Eph) as potential positive regulators of ER-α.

RESULTS

In this study, we demonstrate Eph receptor B4 (EphB4), a member of Eph kinase family, a positive regulator of ER-α in human breast cancer cell lines (MCF-7, T-47D and BT-474). Down-regulation of EphB4 by RNA interference technology impairs estrogen-dependent ER-α transcriptional activity in breast cancer cells. Decreased activity of ER-α after EphB4 knockdown is the consequence of diminished ER-α messenger RNA and protein expression. Furthermore, phosphorylation of Akt, a downstream mediator of EphB4, is reduced following EphB4 silencing.

CONCLUSIONS

Our data suggests EphB4 as an upstream regulator of ER-α in human breast cancer cells by modulating ER-α transcription. The results also suggest Akt as a relevant downstream signaling molecule in this novel EphB4-ER-α pathway.

The metabolic and mitogenic properties of basal insulin analogues

CONTEXT

Retrospective, observational studies have reported an association between diabetes treatment with insulin and a higher incidence of cancer.

OBJECTIVE

Overview the literature for in vitro and in vivo studies of the metabolic and mitogenic properties of basal insulin analogues and assess the implications for clinical use.

METHODS

Relevant studies were identified through PubMed and congress abstract database searches; data on metabolic and mitogenic signalling in relation to insulin treatment of diabetes are included in this review.

RESULTS

The balance of evidence shows that although some analogues have demonstrated mitogenic potency in some in vitro studies in cancer cell lines, these findings do not translate to the in vivo setting in animals or to the clinical setting in humans.

CONCLUSIONS

The current consensus is that there is no clinical or in vivo evidence to indicate that any commercially available insulin analogue has carcinogenic effects. Large-scale, prospective clinical and observational studies will further establish any potential link.

Insulin glargine and cancer risk in patients with diabetes: a meta-analysis

AIM

The role of insulin glargine as a risk factor for cancer is controversial in human studies. The aim of this meta-analysis was to evaluate the relationship between insulin glargine and cancer incidence.

METHODS

All observational studies and randomized controlled trials evaluating the relationship of insulin glargine and cancer risk were identified in PubMed, Embase, Web of Science, Cochrane Library and the Chinese Biomedical Medical Literature Database, through March 2012. Odds ratios (ORs) with corresponding 95% confidence interval (CI) were calculated with a random-effects model. Confidence in the estimates of the obtained effects (quality of evidence) was assessed by using the Grading of Recommendations Assessment, Development, and Evaluation approach.

RESULTS

A total of 11 studies including 448,928 study subjects and 19,128 cancer patients were finally identified for the meta-analysis. Insulin glargine use was associated with a lower odds of cancer compared with non-glargine insulin use (OR 0.81, 95% CI 0.68 to 0.98, P = 0.03; very low-quality evidence). Glargine did not increase the odds of breast cancer (OR 0.99, 95% CI 0.68 to 1.46, P = 0.966; very low-quality evidence). Compared with non-glargine insulin, no significant association was found between insulin glargine and prostate cancer, pancreatic cancer and respiratory tract cancer. Insulin glargine use was associated with lower odds of other site-specific cancer.

CONCLUSIONS

Results from the meta-analysis don't support the link between insulin glargine and an increased risk of cancer and the confidence in the estimates of the effects is very low. Further studies are needed to examine the relation between insulin glargine and cancer risk, especially breast cancer.