Proliferative effects of insulin analogues on mammary epithelial cells

Ginsenosides: changing the basic hallmarks of cancer cells to achieve the purpose of treating breast cancer

In 2021, breast cancer accounted for a substantial proportion of cancer cases and represented the second leading cause of cancer deaths among women worldwide. Although tumor cells originate from normal cells in the human body, they possess distinct biological characteristics resulting from changes in gene structure and function of cancer cells in contrast with normal cells. These distinguishing features, known as hallmarks of cancer cells, differ from those of normal cells. The hallmarks primarily include high metabolic activity, mitochondrial dysfunction, and resistance to cell death. Current evidence suggests that the fundamental hallmarks of tumor cells affect the tissue structure, function, and metabolism of tumor cells and their internal and external environment. Therefore, these fundamental hallmarks of tumor cells enable tumor cells to proliferate, invade and avoid apoptosis. Modifying these hallmarks of tumor cells represents a new and potentially promising approach to tumor treatment. The key to breast cancer treatment lies in identifying the optimal therapeutic agent with minimal toxicity to normal cells, considering the specific types of tumor cells in patients. Some herbal medicines contain active ingredients which can precisely achieve this purpose. In this review, we introduce Ginsenoside's mechanism and research significance in achieving the therapeutic effect of breast cancer by changing the functional hallmarks of tumor cells, providing a new perspective for the potential application of Ginsenoside as a therapeutic drug for breast cancer.

Pancreas and Adverse Drug Reactions: A Literature Review

Adverse drug reactions (ADRs) affecting the pancreas are a heterogeneous group of side effects that cause damage to pancreatic cells. Various mechanisms such as hypersensitization, sphincter of Oddi constriction, direct cytotoxic and metabolic effects on pancreatic cells, and dose-dependent idiosyncrasy lead to intrapancreatic activation of pancreatic enzymes resulting in drug-induced acute pancreatitis. Several medications have been linked with the development of pancreatic cancer. Pancreatic cancer may result from proinflammatory, proliferative, and antiapoptotic effects. Diabetogenic effect of drugs, which is understood as impairment of insulin secretion, may occur due to direct destruction of β cells, systemic toxicity affecting pancreatic islets and cell membrane glucose transporters, induction of Th1-type autoimmune response, and impairment of voltage-gated calcium channels in β cells, endoplasmic reticulum stress, and insulin signaling. A better understanding of ADRs that affect the pancreas may contribute to improving the awareness of clinicians and patients and reducing potential harmful side effects of implemented therapies.

Early Worsening of Retinopathy in Type 1 and Type 2 Diabetes After Rapid Improvement in Glycaemic Control: A Systematic Review

To systematically review the epidemiology of early worsening of diabetic retinopathy (EWDR) after substantial improvements in glycaemic control and evaluate characteristics including risk factors. This systematic review was registered with PROSPERO (CRD42020158252). An electronic literature search was performed according to PRISMA guidelines using MEDLINE, EMBASE, PubMed, Web of Science, Scopus and Cochrane databases and manual reference for the articles published until 2020. Published full-text English language articles that report data on diabetic retinopathy in people with diabetes experiencing a rapid, substantial decrease in HbA1c after going through intensive therapy were included. All articles were screened, data were extracted and methodological quality was evaluated by two independent reviewers using a priori criteria. A total of 346 articles were identified after the removal of duplicates. Data were extracted from 19 full-text articles with a total of 15,588 participants. Included studies varied considerably in terms of patient selection, timing and method of assessing the eye and retinopathy classification. EWDR was reported to occur in a wide range of prevalences; 3.3-47% of participants within 3-84 months after intensification of glycaemic control. Risk factors for EWDR included long duration of diabetes, long-term uncontrolled hyperglycemia, amplitude of and baseline retinopathy severity in both type 1 and type 2 diabetes. The occurrence of EWDR and progression of retinopathy were found to have an association with the amplitude of HbA1c reduction. EWDR has been described in a proportion of people with intensification of glycaemic control. However, the prevalence remains unclear because of methodological differences in the identified studies. Future interventional studies should report retinopathy and visual outcomes using standardized protocols.

Similar Breast Cancer Risk in Women Older Than 65 Years Initiating Glargine, Detemir, and NPH Insulins

OBJECTIVE

To assess whether initiation of insulin glargine (glargine), compared with initiation of NPH or insulin detemir (detemir), was associated with an increased risk of breast cancer in women with diabetes.

RESEARCH DESIGN AND METHODS

This was a retrospective new-user cohort study of female Medicare beneficiaries aged ≥65 years initiating glargine (203,159), detemir (67,012), or NPH (47,388) from September 2006 to September 2015, with follow-up through May 2017. Weighted Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% CIs for incidence of breast cancer according to ever use, cumulative duration of use, cumulative dose of insulin, length of follow-up time, and a combination of dose and length of follow-up time.

RESULTS

Ever use of glargine was not associated with an increased risk of breast cancer compared with NPH (HR 0.97; 95% CI 0.88-1.06) or detemir (HR 0.98; 95% CI 0.92-1.05). No increased risk was seen with glargine use compared with either NPH or detemir by duration of insulin use, length of follow-up, or cumulative dose of insulin. No increased risk of breast cancer was observed in medium- or high-dose glargine users compared with low-dose users.

CONCLUSIONS

Overall, glargine use was not associated with an increased risk of breast cancer compared with NPH or detemir in female Medicare beneficiaries.

Development and Validation of an Image Analysis System for the Measurement of Cell Proliferation in Mammary Glands of Rats

Reliable detection and measurement of cell proliferation are essential in the preclinical assessment of carcinogenic risk of therapeutics. In this context, the assessment of mitogenic potential on mammary glands is crucial in the preclinical safety evaluation of novel insulins. The existing manual counting is time-consuming and subject to operator bias. To standardize the processes, make it faster, and resistant to errors, we developed a semiautomated image analysis system (CEPA software, which is open-source) for counting of proliferating cells in photomicrographs of mammary gland sections of rats labeled with Ki-67. We validated the software and met the predefined targets for specificity, accuracy, and reproducibility. In comparison to manual counting, the respective mean differences in absolute labeling indices (LIs) for CEPA software were 3.12% for user 1 and 3.05% for user 2. The respective regression analysis revealed a good correlation between the CEPA software user and manual counting. Moreover, the CEPA software showed enhanced reproducibility between independent users. The interuser variability is centered around 0 and the absolute difference was about 0.53% LI. Based on validation data, our software has superiority to the manual counting and is a valid and reliable tool for the routine analysis of cell proliferation in mammary glands from rats exposed to insulin analogs.

The relationship between pancreatic cancer and type 2 diabetes: cause and consequence

Pancreatic cancer (PC) is a devastating and lethal malignant disease and it is well known that there is a complex bidirectional relationship between PC and type 2 diabetes mellitus (T2DM). In order to more deeply summarize the relationship between them, this article summarizes the epidemiological data on the relationship between PC and T2DM in the past 5 years, and further explains the mechanism of interaction between them. Meanwhile, it also summed up the effects of drug therapy for T2DM on PC and the impact of T2DM on surgical resection of PC. Epidemiological studies clearly indicate that the risk of PC is increased in patients with T2DM. But increasing epidemiological data points out that PC also acts as a cause of T2DM and new-onset T2DM is sign and consequence of PC. Insulin resistance, hyperinsulinemia, hyperglycemia, and chronic inflammation are the mechanisms of T2DM-Associated PC. Metformin decreases the risk of PC, while insulin therapy increases the risk of PC. Besides, studies have shown that T2DM decreases the survival in patients with PC resection.

The Role of Insulin Glargine and Human Insulin in the Regulation of Thyroid Proliferation Through Mitogenic Signaling

Our aim was to investigate whether human insulin (HI) or insulin glargine treatment could promote the proliferation of thyroid cells and determine the association between type 2 diabetes and thyroid disease. Rats were treated with different doses of HI and insulin glargine. Plasma glucose and the phosphorylation levels of the insulin receptor (IR), insulin-like growth factor 1 receptor (IGF-1R), protein kinase B (Akt), and extracellular signal-regulated kinase 1/2 (ERK1/2) were measured. A total of 105 rats were randomly assigned to three groups as follows: control group, HI group, and glargine group. Both drugs promoted the phosphorylation of IR, Akt, and ERK1/2 in a dose-dependent manner (p < 0.05), and the effect of glargine persisted for longer period. Treatment with ultra-therapeutic doses of HI or glargine (p < 0.05) increased the expression of Ki-67 in thyroid cells. The results demonstrated that therapeutic doses of glargine have a longer-lasting hypoglycemic control than HI. Based on the results, HI or glargine did not stimulate thyroid cell proliferation at therapeutic doses, but high doses did.

Worsening of diabetic retinopathy with rapid improvement in systemic glucose control: A review

Worsening of diabetic retinopathy (DR) is associated with the initiation of effective treatment of glycaemia in some patients with diabetes. It has been associated with risk factors such as poor blood-glucose control and hypertension, and it manifests prior to the long-term benefits of optimizing glycaemic control. The majority of evidence supports an association of large and rapid reductions in blood-glucose levels with early worsening of DR. Despite a general awareness of early worsening within the diabetes community, mechanisms to explain the phenomenon remain speculative. We provide an overview of early worsening of DR and its pathophysiology based on current data. We describe the phenomenon in various settings, including in patients receiving insulin- or non-insulin-based treatments, in those undergoing bariatric surgery, and in pregnant women. We discuss various mechanisms and theories that have been suggested to explain this paradoxical phenomenon, and we summarize the implications of these in clinical practice.

Pancreatic cancer associated with obesity and diabetes: an alternative approach for its targeting

BACKGROUND

Pancreatic cancer (PC) is among foremost causes of cancer related deaths worldwide due to generic symptoms, lack of effective screening strategies and resistance to chemo- and radiotherapies. The risk factors associated with PC include several metabolic disorders such as obesity, insulin resistance and type 2 diabetes mellitus (T2DM). Studies have shown that obesity and T2DM are associated with PC pathogenesis; however, their role in PC initiation and development remains obscure.

MAIN BODY

Several biochemical and physiological factors associated with obesity and/or T2DM including adipokines, inflammatory mediators, and altered microbiome are involved in PC progression and metastasis albeit by different molecular mechanisms. Deep understanding of these factors and causal relationship between factors and altered signaling pathways will facilitate deconvolution of disease complexity as well as lead to development of novel therapies. In the present review, we focuses on the interplay between adipocytokines, gut microbiota, adrenomedullin, hyaluronan, vanin and matrix metalloproteinase affected by metabolic alteration and pancreatic tumor progression.

CONCLUSIONS

Metabolic diseases, such as obesity and T2DM, contribute PC development through altered metabolic pathways. Delineating key players in oncogenic development in pancreas due to metabolic disorder could be a beneficial strategy to combat cancers associated with metabolic diseases in particular, PC.

Pancreatic Cancer and Diabetes Mellitus

PURPOSE OF REVIEW

The relationship between pancreatic ductal adenocarcinoma (PDAC) and diabetes mellitus (DM) is complex. We reviewed the recent medical literature regarding the effect of anti-diabetic medication on PDAC risk and survival, risk of PDAC in DM, and role of DM in early detection of PDAC.

RECENT FINDINGS

Studies report that while some anti-diabetic medications (e.g., metformin) may decrease the risk of PDAC, others (insulin, sulfonylureas and incretin-based therapies) may increase the risk. However, these observations may be subject to protopathic biases. Metformin's anti-tumor activity may have influence overall survival of PDAC, but epidemiological reports have largely been inconsistent to defend these findings due to heterogeneous methodologies. There is congruent data to support the association between DM and PDAC, with an inverse relationship to DM duration. Older subjects with new-onset DM are the only known high-risk group for PDAC, and strategy using this group for early detection has led to development of clinical risk prediction models that define a very high-risk PDAC group. Role of anti-diabetic medication in PDAC risk modification or survival is controversial. With successful efforts to distinguish type 2-DM from PDAC-DM using risk-stratifying models, there is an opportunity to initiate screening protocols for early detection of PDAC in a sub-set of DM subjects.

Long-Term Use of Long-Acting Insulin Analogs and Breast Cancer Incidence in Women With Type 2 Diabetes

Purpose

The association between long-acting insulin analogs and increased breast cancer risk is uncertain, particularly with the short follow-up in previous studies. We assessed this risk long term in women with type 2 diabetes.

Methods

A population-based cohort of women 40 years or older, all of whom were treated with long-acting (glargine, detemir) or neutral protamine Hagedorn (NPH) insulin between 2002 and 2012, was formed using the United Kingdom’s Clinical Practice Research Datalink. Women were followed until February 2015 or breast cancer diagnosis. Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) and 95% CIs of incident breast cancer, comparing long-acting insulin analogs with NPH overall, as well as by duration and cumulative dose.

Results

The cohort included 22,395 women who received insulin treatment, with 321 incident breast cancer events occurring during up to 12 years of follow-up (incidence rate 3.3 per 1,000 person-years). Compared with NPH insulin, insulin glargine was associated with an increased risk of breast cancer (HR, 1.44; 95% CI, 1.11 to 1.85), mainly increasing 5 years after glargine initiation (HR, 2.23; 95% CI, 1.32 to 3.77) and after > 30 prescriptions (HR, 2.29; 95% CI, 1.26 to 4.16). The risk was particularly elevated among prior insulin users (HR, 1.53; 95% CI, 1.10 to 2.12) but not for new users, which included fewer patients and for which one cannot rule out an HR of 1.81. The risk associated with insulin detemir was not significantly elevated (HR, 1.17; 95% CI, 0.77 to 1.77).

Conclusion

Long-term use of insulin glargine is associated with an increased risk of breast cancer in women with type 2 diabetes. The risk associated with insulin detemir remains uncertain because there are fewer users of this insulin.

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.

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.

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.

A framework for the in vitro evaluation of cancer-relevant molecular characteristics and mitogenic potency of insulin analogues

Clinically prescribed insulin analogues are putatively linked with increased cancer risk. We developed a framework for the mandated regulatory in vitro evaluation of cancer-relevant bioassays for comparisons of insulin analogues, and showed that the cell-specific IGF-IR/IR ratio is crucial for interpretation.

Epidemiological and laboratory studies raise the possibility of a link between clinically prescribed insulin analogues and increased cancer risk. Accordingly, there is a regulatory mandate for cancer-related pre-clinical safety evaluation during insulin analogue development, but currently, there is no standardized framework for such in vitro evaluation. We tested human insulin; the super-mitogenic insulin, X10 and insulin-like growth factor I, in four cancer cell lines with a range of insulin-like growth factor-I receptor (IGF-IR)/IR (insulin receptor) ratios (HCT 116, HT-29, COLO 205 and MCF7) and related these to IGF-IR and IR expression in 17 human adenocarcinomas. All cell types were IR-A isoform dominant. We determined IGF-IR/IR signalling pathway endpoints in dose- and time-varying experiments, and performed mitogenic dose–response equivalent assays to derive EC₅₀ values, and correlated these with IGF-IR/IR ratios. We superimposed relative EC₅₀ values onto data from the literature in a meta-analysis. The IGF-IR/IR ratios varied from <1 to 12 in the selected cell lines; similar pattern ranges were observed in human adenocarcinomas. The three ligands demonstrated differential IR/IGF-IR and Akt phosphorylation, which correlated with cell-specific IGF-IR/IR ratios. Mitogenic profiles of X10 mimicked those for insulin-like growth factor I (IGF-I) and correlated with IGF-IR/IR ratios. The meta-analysis, adding data from five additional studies, supported the hypothesis that ligand mitogenic potency, relative to human insulin, increases with increasing cell-specific IGF-IR/IR ratio. This study established a framework for the in vitro evaluation of cancer-relevant bioassays for comparisons of insulin analogues, and specifically consolidated earlier studies that determination of the cell-specific IGF-IR/IR ratio is crucial for the interpretation of ranking relative biological activities.

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.

Risk of breast cancer by individual insulin use: an international multicenter study

OBJECTIVE Several studies have been published in 2009 suggesting a possible association between insulin glargine and increased risk of malignancies, including breast cancer. The objective of this study was to assess the relation between the individual insulins (glargine, aspart, lispro, and human insulin) and development of breast cancer. RESEARCH DESIGN AND METHODS Seven hundred seventy-five incident cases of primary invasive or in situ carcinoma breast cancer occurring in women with diabetes from 92 centers in the U.K., Canada, and France were matched to a mean of 3.9 diabetic community control subjects (n = 3,050; recruited from 580 general practices) by country, age, recruitment date, and diabetes type and management. The main risk model was a multivariate conditional logistic regression model with case/control status as the dependent variable and individual insulin use, 8 years preceding the index date, as the independent variable, controlling for past use of any insulin, oral antidiabetes drugs, reproductive factors, lifestyle, education, hormone replacement therapy and history of contraceptive use, BMI, comorbidities, diabetes duration, and annual number of physician visits. Glargine was also compared with every other insulin by computing all ratios using the variance-covariance matrix of logistic model parameters. RESULTS Adjusted odds ratios of breast cancer for each type of insulin versus no use of that insulin were 1.04 (95% CI 0.76-1.44) for glargine, 1.23 (0.79-1.92) for lispro, 0.95 (0.64-1.40) for aspart, and 0.81 (0.55-1.20) for human insulin. Two-by-two comparisons found no difference between glargine and the different types of insulins. Insulin dosage or duration of use and tumor stage did not change the results. CONCLUSIONS This international study found no difference in the risk of developing breast cancer in patients with diabetes among the different types of insulin with short- to mid-term duration of use. Longer-term studies would be of interest.

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.

Diabetes and pancreatic cancer

The relationship between diabetes and pancreatic cancer is complex. Diabetes or impaired glucose tolerance is present in more than 2/3rd of pancreatic cancer patients. Epidemiological studies have consistently shown a modest increase in the risk of pancreatic cancer in type 2 diabetes, with an inverse relationship to duration of disease. Additionally, recent studies suggest that anti-diabetic medications may modulate the risk of pancreatic cancer in type 2 diabetes. Subjects >50 years of age with new onset diabetes are at higher risk of having pancreatic cancer. However, to screen new-onset diabetes for pancreatic cancer, additional markers are needed that can distinguish pancreatic cancer-associated diabetes from type 2 diabetes.

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.

The epidemiology and molecular mechanisms linking obesity, diabetes, and cancer

The worldwide epidemic of obesity is associated with increasing rates of the metabolic syndrome and type 2 diabetes. Epidemiological studies have reported that these conditions are linked to increased rates of cancer incidence and mortality. Obesity, particularly abdominal obesity, is associated with insulin resistance and the development of dyslipidemia, hyperglycemia, and ultimately type 2 diabetes. Although many metabolic abnormalities occur with obesity and type 2 diabetes, insulin resistance and hyperinsulinemia appear to be central to these conditions and may contribute to dyslipidemia and altered levels of circulating estrogens and androgens. In this review, we will discuss the epidemiological and molecular links between obesity, type 2 diabetes, and cancer, and how hyperinsulinemia and dyslipidemia may contribute to cancer development. We will discuss how these metabolic abnormalities may interact with estrogen signaling in breast cancer growth. Finally, we will discuss the effects of type 2 diabetes medications on cancer risk.

Insulin and its analogues and their affinities for the IGF1 receptor

Insulin analogues have been developed in an attempt to achieve a more physiological replacement of insulin and thereby a better glycaemic control. However, structural modification of the insulin molecule may result in altered binding affinities and activities to the IGF1 receptor (IGF1R). As a consequence, insulin analogues may theoretically have an increased mitogenic action compared to human insulin. In view of the lifelong exposure and large patient populations involved, insulin analogues with an increased mitogenic effect in comparison to human insulin may potentially constitute a major health problem, since these analogues may possibly induce the growth of pre-existing neoplasms. This hypothesis has been evaluated extensively in vitro and also in vivo by using animal models. In vitro, all at present commercially available insulin analogues have lower affinities for the insulin receptor (IR). Although it has been suggested that especially insulin analogues with an increased affinity for the IGF1R (such as insulin glargine) are more mitogenic when tested in vitro in cells expressing a high proportion of IGF1R, the question remains whether this has any clinical consequences. At present, there are several uncertainties which make it very difficult to answer this question decisively. In addition, recent data suggest that insulin (or insulin analogues)-mediated stimulation of IRs may play a key role in the progression of human cancer. More detailed information is required to elucidate the exact mechanisms as to how insulin analogues may activate the IR and IGF1R and how this activation may be linked to mitogenesis.

Differential impact of structurally different anti-diabetic drugs on proliferation and chemosensitivity of acute lymphoblastic leukemia cells

Hyperglycemia during hyper-CVAD chemotherapy is associated with poor outcomes of acute lymphoblastic leukemia (ALL) (Cancer 2004; 100: 1179-85). The optimal clinical strategy to manage hyperglycemia during hyper-CVAD is unclear. To examine whether anti-diabetic pharmacotherapy can influence chemosensitivity of ALL cells, we examined the impacts of different anti-diabetic agents on ALL cell lines and patient samples. Pharmacologically achievable concentrations of insulin, aspart and glargine significantly increased the number of ALL cells, and aspart and glargine did so at lower concentrations than human insulin. In contrast, metformin and rosiglitazone significantly decreased the cell number. Human insulin and analogs activated AKT/mTOR signaling and stimulated ALL cell proliferation (as measured by flow cytometric methods), but metformin and rosiglitazone blocked AKT/mTOR signaling and inhibited proliferation. Metformin 500 μM and rosiglitazone 10 μM were found to sensitize Reh cells to daunorubicin, while aspart, glargine and human insulin (all at 1.25 mIU/L) enhanced chemoresistance. Metformin and rosiglitazone enhanced daunorubicin-induced apoptosis, while insulin, aspart and glargine antagonized daunorubicin-induced apoptosis. In addition, metformin increased etoposide-induced and L-asparaginase-induced apoptosis; rosiglitazone increased etoposide-induced and vincristine-induced apoptosis. In conclusion, our results suggest that use of insulins to control hyperglycemia in ALL patients may contribute to anthracycline chemoresistance, while metformin and thiazolidinediones may improve chemosensitivity to anthracycline as well as other chemotherapy drugs through their different impacts on AKT/mTOR signaling in leukemic cells. Our data suggest that the choice of anti-diabetic pharmacotherapy during chemotherapy may influence clinical outcomes in ALL.

A fully human, allosteric monoclonal antibody that activates the insulin receptor and improves glycemic control

Many patients with diabetes mellitus (both type 1 and type 2) require therapy to maintain normal fasting glucose levels. To develop a novel treatment for these individuals, we used phage display technology to target the insulin receptor (INSR) complexed with insulin and identified a high affinity, allosteric, human monoclonal antibody, XMetA, which mimicked the glucoregulatory, but not the mitogenic, actions of insulin. Biophysical studies with cultured cells expressing human INSR demonstrated that XMetA acted allosterically and did not compete with insulin for binding to its receptor. XMetA was found to function as a specific partial agonist of INSR, eliciting tyrosine phosphorylation of INSR but not the IGF-IR. Although this antibody activated metabolic signaling, leading to enhanced glucose uptake, it neither activated Erk nor induced proliferation of cancer cells. In an insulin resistant, insulinopenic model of diabetes, XMetA markedly reduced elevated fasting blood glucose and normalized glucose tolerance. After 6 weeks, significant improvements in HbA(1c), dyslipidemia, and other manifestations of diabetes were observed. It is noteworthy that hypoglycemia and weight gain were not observed during these studies. These studies indicate, therefore, that allosteric monoclonal antibodies have the potential to be novel, ultra-long acting, agents for the regulation of hyperglycemia in diabetes.

Insulin analogs and cancer

Today, insulin analogs are used in millions of diabetic patients. Insulin analogs have been developed to achieve more physiological insulin replacement in terms of time-course of the effect. Modifications in the amino acid sequence of the insulin molecule change the pharmacokinetics and pharmacodynamics of the analogs in respect to human insulin. However, these changes can also modify the molecular and biological effects of the analogs. The rapid-acting insulin analogs, lispro, aspart, and glulisine, have a rapid onset and shorter duration of action. The long-acting insulin analogs glargine and detemir have a protracted duration of action and a relatively smooth serum concentration profile. Insulin and its analogs may function as growth factors and therefore have a theoretical potential to promote tumor proliferation. A major question is whether analogs have an increased mitogenic activity in respect to insulin. These ligands can promote cell proliferation through many mechanisms like the prolonged stimulation of the insulin receptor, stimulation of the IGF-1 receptor (IGF-1R), prevalent activation of the extracellular-signaling-regulated kinase (ERK) rather than the protein kinase B (PKB/AKT) intracellular post-receptor pathways. Studies on in vitro models indicate that short-acting analogs elicit molecular and biological effects that are similar to those of insulin. In contrast, long-acting analogs behave differently. Although not all data are homogeneous, both glargine and detemir have been found to have a decreased binding to receptors for insulin but an increased binding to IGF-1R, a prevalent activation of the ERK pathway, and an increased mitogenic effect in respect to insulin. Recent retrospective epidemiological clinical studies have suggested that treatment with long-acting analogs (specifically glargine) may increase the relative risk for cancer. Results are controversial and methodologically weak. Therefore prospective clinical studies are needed to evaluate the possible tumor growth-promoting effects of these insulin analogs.

Risk of cancer in patients on insulin glargine and other insulin analogues in comparison with those on human insulin: results from a large population-based follow-up study

AIMS/HYPOTHESIS

Several publications suggest an association between certain types of insulin and cancer, but with conflicting results. We investigated whether insulin glargine (A21Gly,B31Arg,B32Arg human insulin) is associated with an increased risk of cancer in a large population-based cohort study.

METHODS

Data for this study were obtained from dispensing records from community pharmacies individually linked to hospital discharge records from 2.5 million individuals in the Netherlands. In a cohort of incident users of insulin, the association between insulin glargine and other insulin analogues, respectively, and cancer was analysed in comparison with human insulin using Cox proportional hazard models with cumulative duration of drug use as a time-varying determinant. The first hospital admission with a primary diagnosis of cancer was considered as the main outcome; secondary analyses were performed with specific cancers as outcomes.

RESULTS

Of the 19,337 incident insulin users enrolled, 878 developed cancer. Use of insulin glargine was associated with a lower risk of malignancies in general in comparison with human insulin (HR 0.75, 95% CI 0.71, 0.80). In contrast, an increased risk was found for breast cancer (HR 1.58, 95% CI 1.22, 2.05). Dose-response relationships could not be identified.

CONCLUSION/INTERPRETATION

Users of insulin glargine and users of other insulin analogues had a lower risk of cancer in general than those using human insulin. Both associations might be a consequence of residual confounding, lack of adherence or competing risk. However, as in previous studies, we demonstrated an increased risk of breast cancer in users of insulin glargine in comparison with users of human insulin.

Protected graft copolymer (PGC) basal formulation of insulin as potentially safer alternative to Lantus® (insulin-glargine): a streptozotocin-induced, diabetic Sprague Dawley rats study

PURPOSE

To develop a long-acting formulation of native human insulin with a similar pharmacodynamics (PD) profile as the insulin analogue insulin glargine (Lantus®, Sanofi-Aventis) with the expectation of retaining native human insulin's superior safety profile as insulin glargine is able to activate the insulin-like growth factor 1 (IGF-1) receptor and is linked to a number of malignancies at a higher rate than regular human insulin.

METHODS

Development of protected graft copolymer (PGC) excipients that bind native human insulin non-covalently and testing blood glucose control obtained with these formulations in streptozotocin-induced diabetic Sprague Dawley rats compared to equally dosed insulin glargine.

RESULTS

PGC-formulations of native human insulin are able to control blood glucose to the same extent and for the same amount of time after s.c. injection as the insulin analogue insulin glargine. No biochemical changes were made to the insulin that would change receptor binding and activation with their possible negative effects on the safety of the insulin.

CONCLUSION

Formulation with the PGC excipient offers a viable alternative to biochemically changing insulin or other receptor binding peptides to improve PD properties.

Insulin action on H292 bronchial carcinoma cells as compared to normal bronchial epithelial cells

Inhaled insulin may contribute to bronchial carcinoma due to IGF-I receptor activation by high local concentrations. Therefore, effects of insulin and IGF-I on human bronchial carcinoma cells (H292) and normal bronchial epithelium cells (HBE) were studied. TGF-β was included since it also influences carcinoma progression. H292 and HBE cells expressed both the insulin receptor and the IGF-I receptor; in H292 cells an additional, shorter, splicing variant (IR-A) of the insulin receptor was present. Insulin receptor expression was around four to five times higher in H292 than in HBE cells at mRNA and protein levels. Insulin and TGF-β exerted contrary actions on proliferation and gene expression in H292 cells. Genes regulated by insulin, IGF-I, and TGF-β were linked to inflammation, cell adhesion, muscle contraction and differentiation. Insulin and IGF-I also suppressed DNA repair genes. EC(50) for insulin-induced proliferation was around 5 nM in H292 and around 30 nM HBE cells. The EC(50) values for gene expression ranged from 9 to 90 nM in both cell types, dependent on the gene studied. In H292 cells, the proliferative response was much stronger if TGF-β was present. In HBE cells this interaction of insulin and TGF-β was not observed, and changes in gene expression were mostly lower by at least 10-fold as compared to H292. All in all, the insulin effects in H292 were generally much stronger than in HBE cells and - with regard to proliferation - occurred at lower concentrations. Thus, insulin will hardly induce cancer from normal bronchial cells but may favour progression of pre-existing tumours.

Insulin receptor and cancer

The widespread epidemic of obesity and type 2 diabetes has raised concern for the impact of these disorders as risk factors for cancer and has renewed the interest for studies regarding the involvement of hyperinsulinemia and insulin receptor (IR) in cancer progression. Overexpression of IR in cancer cells may explain their increased sensitivity to hyperinsulinemia. Moreover, IR isoform A (IR-A) together with autocrine production of its ligand IGF2 is emerging as an important mechanism of normal and cancer stem cell expansion and is a feature of several malignancies. De novo activation of the IR-A/IGF2 autocrine loop also represents a mechanism of resistance to anticancer therapies. Increasing knowledge of the IR role in cancer has important implications for cancer prevention, which should include control of insulin resistance and hyperinsulinemia in the population and meticulous evaluation of new antidiabetic drugs for their metabolic:mitogenic ratio. We are now aware that several anticancer treatments may induce or worsen insulin resistance that may limit therapy efficacy. Future anticancer therapies need to target the IR-A pathway in order to inhibit the tumor promoting effect of IR without impairing the metabolic effect of insulin.

Differences in bioactivity between human insulin and insulin analogues approved for therapeutic use- compilation of reports from the past 20 years

In order to provide comprehensive information on the differences in bioactivity between human insulin and insulin analogues, published in vitro comparisons of human insulin and the rapid acting analogues insulin lispro (Humalog®), insulin aspart ( NovoRapid®), insulin glulisine (Apidra®), and the slow acting analogues insulin glargine (Lantus®), and insulin detemir (Levemir®) were gathered from the past 20 years (except for receptor binding studies). A total of 50 reports were retrieved, with great heterogeneity among study methodology. However, various differences in bioactivity compared to human insulin were obvious (e.g. differences in effects on metabolism, mitogenesis, apoptosis, intracellular signalling, thrombocyte function, protein degradation). Whether or not these differences have clinical bearings (and among which patient populations) remains to be determined.

Type 2 diabetes and cancer: what is the connection?

Epidemiological studies have demonstrated an association between type 2 diabetes and cancer. Type 2 diabetes is characterized by insulin resistance and hyperinsulinemia. Hyperinsulinemia may lead to cancer through insulin's effect on its cognate receptor and the insulin-like growth factor system. The effects of insulin and insulin-like growth factor I on cancer development and progression have been demonstrated in animal and human studies. Type 2 diabetes has been positively associated with cancers of the breast, colon, and pancreas. An inverse relationship has been observed between type 2 diabetes and prostate cancer, and this may be due to lower testosterone levels in men with type 2 diabetes. Medications used to treat type 2 diabetes may affect cancer cells directly or indirectly by affecting serum insulin levels. Hyperinsulinemia may be an important risk factor for cancer as well as a target for cancer therapy.

Cancer risk in type 2 diabetes mellitus: metabolic links and therapeutic considerations

Type 2 diabetes mellitus (DM2) is increasing in incidence, creating worldwide public health concerns and impacting morbidity and mortality rates. An increasing number of studies have demonstrated shared associations between DM2 and malignancy, including key clinical, biochemical, and metabolic commonalities. This paper will attempt to explore the relationship between the various types of cancer and diabetes, the common metabolic pathways underlying cancer development, and the potential impact of various antidiabetes therapies on cancer risk.

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.

Controversies in the use of insulin analogues

INTRODUCTION

In recent years, insulin analogues have been developed in order to improve the pharmacological parameters of insulin and to better mimic endogenous insulin output. Given that some of the modifications introduced into insulin analogues are located in a domain involved in a potential interaction with the insulin-like growth factor-I receptor (IGF-IR), it has been postulated that certain analogues may display IGF-I-like activities.

AREAS COVERED

We review the recent literature investigating the risk of malignant neoplasms and mortality in diabetic patients treated either with human insulin or with one of three insulin analogues (lispro, aspart, and glargine). We examine how critical analyses are consistent with the notion that the use of insulin glargine is associated with a possible increased risk of tumors in humans.

EXPERT OPINION

The introduction of insulin analogues has had a major impact in diabetes care. However, the benefit of some of these new insulins for the patient has yet to be demonstrated. Furthermore, research is needed to clarify whether insulin glargine is more strongly associated with cancer risk compared with other insulins.

Risk of cancer in patients receiving insulin glargine

PURPOSE

The risk of malignancy in patients using insulin glargine was evaluated.

SUMMARY

Patients with diabetes mellitus have increased rates of cancers including breast, colon, and pancreatic cancers. Since nondiabetic patients with increased levels of insulin have similar rates of the same cancers, hyperinsulinemia could be key. Normally, insulin produces metabolic effects and insulin-like growth factor-I (IGF-I) produces mitogenic effects. Since the molecules are structurally similar, it is possible for insulin to act like IGF-I, promoting mitogenicity. Concern that insulin may promote the growth of some cancers is heightened with insulin analogues, since changing the structure of human insulin could produce molecules with increased mitogenic potential. In vivo, insulin glargine has been shown to have greater mitogenic potential than human insulin. It is unknown whether this occurs in vitro, because the insulin glargine molecule is transformed once injected. Studies published in 2009 suggest that patients on insulin glargine could be at greater risk for cancer than patients on other antidiabetes therapies, but the trial results are conflicting. In response, the Food and Drug Administration, American Diabetes Association, American Association of Clinical Endocrinologists, and European Association for the Study of Diabetes have formally stated that patients should continue to use insulin glargine until more information is available.

CONCLUSION

Studies on the relationship between insulin glargine and cancer have been inconclusive.

Diabetes mellitus and increased risk of cancer: focus on metformin and the insulin analogs

Type 2 diabetes mellitus has been associated with an increased risk of hepatic, pancreatic, colon, endometrial, breast, and bladder cancer. Although a mechanism of action for the increased risk has been postulated, no definitive evidence has been completely elucidated in the medical literature. Results of recently released studies documented the use of specific antidiabetic drugs with increased rates of cancer. The insulin analog glargine was the focus of four observational studies published in 2009 that outlined an increase in the rates of cancer associated with its use. In contrast, the use of metformin has been shown to possibly decrease the rate of specific cancers when used in the treatment of type 2 diabetes. These data regarding cancer risk and antidiabetic drugs are contradictory and at this time are inconclusive. Until results of long-term randomized prospective studies are available to elucidate a correlation with cancer and insulin, we must continue treating diabetes in order to avert the long-term complications of the disease.

High dose human insulin and insulin glargine promote T24 bladder cancer cell proliferation via PI3K-independent activation of Akt

BACKGROUND

This study was to investigate the effects of human insulin and insulin glargine on proliferation of T24 human bladder cancer cells and the implication of the PI3K/Akt and MEK/ERK1/2 pathways.

METHODS

After exposure to insulin or glargine at the indicated concentrations for certain time courses, in the absence or presence of inhibitor for MEK (PD98059) or PI3K (LY294002), T24 cell proliferation was evaluated by CCK-8 assay. Phosphorylation of Akt and ERK1/2 was analyzed by Western blot.

RESULTS

Insulin and glargine similarly induced phosphorylation of Akt and slight increases in T24 cell proliferation at 10-100IU/L. LY294002 remarkably reduced T24 cell proliferation in all groups. However, in the presence of LY294002, cell growth was still promoted by insulin and glargine relative to LY294002-treated group. Accordingly, LY294002 profoundly reduced protein levels of pAkt, while insulin and glargine increased pAkt in T24 cells pretreated with LY294002 as compared with cells treated with LY294002 alone. PD98059 reduced pERK while enhanced T24 cell proliferation. Insulin and glargine increased pERK at 15, 30, 60 min, not at 24h.

CONCLUSIONS

High dose human insulin and insulin glargine similarly promoted T24 bladder cancer cell proliferation via PI3K-independent activation of Akt.

The insulin receptor: a new target for cancer therapy

A large body of evidences have shown that both the IGF-I receptor (IGF-IR) and the insulin receptor (IR) play a role in cancer development and progression. In particular, IR overactivation by IGF-II is common in cancer cells, especially in dedifferentiated/stem-like cells. In spite of these findings, until very recently, only IGF-IR but not IR has been considered a target in cancer therapy. Although several preclinical studies have showed a good anti-cancer activity of selective anti-IGF-IR drugs, the results of the clinical first trials have been disappointing. In fact, only a small subset of malignant tumors has shown an objective response to these therapies. Development of resistance to anti-IGF-IR drugs may include upregulation of IR isoform A (IR-A) in cancer cells and its overactivation by increased secretion of autocrine IGF-II. These findings have led to the concept that co-targeting IR together with IGF-IR may increase therapy efficacy and prevent adaptive resistance to selective anti-IGF-IR drugs. IR blockade should be especially considered in tumors with high IR-A:IGF-IR ratio and high levels of autocrine IGF-II. Conversely, insulin sensitizers, which ameliorate insulin resistance associated with metabolic disorders and cancer treatments, may have important implications for cancer prevention and management. Only few drugs co-targeting the IR and IGF-IR are currently available. Ideally, future IR targeting strategies should be able to selectively inhibit the tumor promoting effects of IR without impairing its metabolic effects.

Retinal Nerve Fiber Layer Decrease during Glycemic Control in Type 2 Diabetes

Purpose. To assess an effect of glycemic control on retinal nerve fiber layer (RNFL) in type 2 diabetes mellitus. Methods. Thirty-eight eyes of 38 patients with type 2 diabetes undergoing blood glucose regulation were enrolled. All patients were examined at (1) initial visit, (2) 1 month, (3) 2 months, and (4) 4-month after the initial examination. On each occasion, glycosylated hemoglobin (HbA1c) levels and optical coherence tomography (OCT) scanning for RNFL thickness were evaluated. 360 degree circular OCT scans with a diameter of 3.4 mm centered on the optic disc were performed. Results. Significant RNFL decrease was seen in the superior area between initial and 4 months examination (P = .043). The relationship between the changes in HbA1c and the changes in RNFL thickness was observed in superior, temporal, and inferior area (P < .05) at 4 months. Conclusions. This study suggests that the glycemic control affects RNFL within 4 months.

Treatment with insulin glargine (Lantus) increases the proliferative potency of the serum of patients with type-1 diabetes: a pilot study on MCF-7 breast cancer cells

CONTEXT AND OBJECTIVE

Insulin glargine (Lantus) stimulates growth of MCF-7 cells stronger than human insulin. We investigated if serum from diabetic patients treated with glargine versus human insulin may display a similar effect.

METHODS

Pairs of serum samples from 31 C-peptide negative type-1 diabetic patients were investigated. In cross-over fashion, 23 patients were treated with glargine plus rapid-acting insulin analogues, and similar doses of human NPH and rapid-acting insulin. For comparison, eight patients were treated with insulin detemir (Levemir) and human NPH. MCF-7 cells were incubated with 10% serum and proliferation was assessed after 72 hours.

RESULTS

Serum containing insulin glargine was 1.11(95% CI 1.05-1.18) fold more mitogenic than human insulin-containing serum (p < 0.005); mitogenicity of serum containing detemir was 0.99(95% CI 0.98-1.02) fold that of human insulin-containing serum.

CONCLUSION

The serum of diabetic patients was slightly stronger mitogenic when using glargine as compared to human insulin or detemir for treatment.

Appraising the mitogenicity of insulin analogues relative to human insulin-response to: Weinstein D, Simon M, Yehezkel E, Laron Z, Werner H. Insulin analogues display IGF-I-like mitogenic and anti-apoptotic activity in cultured cancer cells. Diabetes Metab Res Rev 2009; 25(1): 41-9

Interest in mitogenic and potentially carcinogenic effects of insulin and insulin analogues has been renewed by several recent publications that have examined the relationship between cancer and insulin analogues. Actions mediated through the insulin-like growth factor-I receptor in a hyperinsulinaemic state have been implicated mechanistically. Both type 2 diabetes and endogenously elevated insulin-like growth factor-I have been epidemiologically linked to malignancies. Therefore, in vitro mitogenic effects and binding affinities of the various analogues have been analysed. A recent publication by Weinstein et al. studied the in vitro mitogenic and anti-apoptotic activities of insulin analogues, and their conclusion asserts that insulins glargine, detemir, and lispro displayed proliferative and anti-apoptotic effects in a number of malignant cell lines. However, their conclusions are not supported by the data which are not complete and lack clear statistical significance. This data should be interpreted cautiously in light of all other presently available scientific evidence. Prospective, randomized clinical trials will best address any direct relationship between insulin analogues and cancer. Until those studies are designed and completed, clinicians should consider the demonstrated strong benefit of glycaemic control in balance with any alleged risk.

Supramolecular protein engineering: design of zinc-stapled insulin hexamers as a long acting depot

Bottom-up control of supramolecular protein assembly can provide a therapeutic nanobiotechnology. We demonstrate that the pharmacological properties of insulin can be enhanced by design of "zinc staples" between hexamers. Paired (i, i+4) His substitutions were introduced at an alpha-helical surface. The crystal structure contains both classical axial zinc ions and novel zinc ions at hexamer-hexamer interfaces. Although soluble at pH 4, the combined electrostatic effects of the substitutions and bridging zinc ions cause isoelectric precipitation at neutral pH. Following subcutaneous injection in a diabetic rat, the analog effected glycemic control with a time course similar to that of long acting formulation Lantus. Relative to Lantus, however, the analog discriminates at least 30-fold more stringently between the insulin receptor and mitogenic insulin-like growth factor receptor. Because aberrant mitogenic signaling may be associated with elevated cancer risk, such enhanced specificity may improve safety. Zinc stapling provides a general strategy to modify the pharmacokinetic and biological properties of a subcutaneous protein depot.

Diabetes, insulin treatment, and cancer risk: what is the evidence?

Diabetes, in particular type 2, is associated with an increased incidence of cancer. Although the mortality attributable to cancer in type 2 diabetes is overshadowed by that due to cardiovascular disease, emerging data from epidemiologic studies suggest that insulin therapy may confer added risk for cancer, perhaps mediated by signaling through the IGF-1 (insulin-like growth factor-1) receptor. Co-administered metformin seems to mitigate the risk associated with insulin. A recent series of publications in Diabetologia addresses the possibility that glargine, the most widely used long-acting insulin analogue, may confer a greater risk than other insulin preparations, particularly for breast cancer. This has led to a heated controversy. Despite this, there is a consensus that the currently available data are not conclusive and should not be the basis for any change in practice. Further studies and more thorough surveillance of cancer in diabetes are needed to address this important issue.

MCF-7 human mammary adenocarcinoma cells exhibit augmented responses to human insulin on a collagen IV surface

Human mammary cell lines are extensively used for preclinical safety assessment of insulin analogs. However, it is essentially unknown how mitogenic responses can be optimized in mammary cell-based systems. We developed an insulin mitogenicity assay in MCF-7 human mammary adenocarcinoma cells, under low serum (0.1% FCS) and phenol red-free conditions, with 3H thymidine incorporation as endpoint. Based on EC50 values determined from 10-fold dilution series, beta-estradiol was the most potent mitogen, followed by human IGF-1, human AspB10 insulin and native human insulin. AspB10 insulin was significantly more mitogenic than native insulin, validating the ability of the assay to identify hypermitogenic human insulin analogs. With MCF-7 cells on a collagen IV surface, the ranking of mitogens was maintained, but fold mitogenic responses and dynamic range and steepness of dose-response curves were increased. Also, PI3K pathway activation by insulin was enhanced on a collagen IV surface. This study provided the first determination and ranking of the mitogenic potencies of standard reference compounds in an optimized MCF-7 assay. The optimized MCF-7 assay described here is of relevance for in vitro toxicological testing and carcinogenicity safety assessment of new insulin compounds.

Insulin receptor isoforms and insulin receptor/insulin-like growth factor receptor hybrids in physiology and disease

In mammals, the insulin receptor (IR) gene has acquired an additional exon, exon 11. This exon may be skipped in a developmental and tissue-specific manner. The IR, therefore, occurs in two isoforms (exon 11 minus IR-A and exon 11 plus IR-B). The most relevant functional difference between these two isoforms is the high affinity of IR-A for IGF-II. IR-A is predominantly expressed during prenatal life. It enhances the effects of IGF-II during embryogenesis and fetal development. It is also significantly expressed in adult tissues, especially in the brain. Conversely, IR-B is predominantly expressed in adult, well-differentiated tissues, including the liver, where it enhances the metabolic effects of insulin. Dysregulation of IR splicing in insulin target tissues may occur in patients with insulin resistance; however, its role in type 2 diabetes is unclear. IR-A is often aberrantly expressed in cancer cells, thus increasing their responsiveness to IGF-II and to insulin and explaining the cancer-promoting effect of hyperinsulinemia observed in obese and type 2 diabetic patients. Aberrant IR-A expression may favor cancer resistance to both conventional and targeted therapies by a variety of mechanisms. Finally, IR isoforms form heterodimers, IR-A/IR-B, and hybrid IR/IGF-IR receptors (HR-A and HR-B). The functional characteristics of such hybrid receptors and their role in physiology, in diabetes, and in malignant cells are not yet fully understood. These receptors seem to enhance cell responsiveness to IGFs.