Obesity and cancer

Insulin Receptor Isoforms Differently Regulate Cell Proliferation and Apoptosis in the Ligand-Occupied and Unoccupied State

The insulin receptor (IR) presents two isoforms (IR-A and IR-B) that differ for the α-subunit C-terminal. Both isoforms are expressed in all human cells albeit in different proportions, yet their functional properties-when bound or unbound to insulin-are not well characterized. From a cell model deprived of the Insulin-like Growth Factor 1 Receptor (IGF1-R) we therefore generated cells exhibiting no IR (R-shIR cells), or only human IR-A (R-shIR-A), or exclusively human IR-B (R-shIR-B) and we studied the specific effect of the two isoforms on cell proliferation and cell apoptosis. In the absence of insulin both IR-A and IR-B similarly inhibited proliferation but IR-B was 2–3 fold more effective than IR-A in reducing resistance to etoposide-induced DNA damage. In the presence of insulin, IR-A and IR-B promoted proliferation with the former significantly more effective than the latter at increasing insulin concentrations. Moreover, only insulin-bound IR-A, but not IR-B, protected cells from etoposide-induced cytotoxicity. In conclusion, IR isoforms have different effects on cell proliferation and survival. When unoccupied, IR-A, which is predominantly expressed in undifferentiated and neoplastic cells, is less effective than IR-B in protecting cells from DNA damage. In the presence of insulin, particularly when present at high levels, IR-A provides a selective growth advantage.

Impact of Adjunctive Pharmacotherapy With Intragastric Balloons for the Treatment of Obesity

BACKGROUND

We conducted this study to compare the weight loss outcome of intragastric balloons (IGBs) in conjunction with pharmacotherapy vs IGB and intensive lifestyle changes alone.

METHODS

This was a multicenter, non-randomized, retrospective study involving 4 academic hospitals. Patients underwent IGB placement with or without concomitant anti-obesity pharmacotherapy. The primary outcome was percent total weight loss (TBWL) after IGB placement at 6 and 12 months.

RESULTS

This study included 102 patients, with 23 patients (mean age 46.6 years, 82.6% female) treated with IGB/pharmacotherapy and 79 patients (mean age 46.0 years, 88.6% female) treated with IGB/lifestyle modifications. Patients had a 100% follow-up rate at 6 and 12 months. At 6 months following IGB placement, both groups achieved a similar %TBWL. At 12 months, %TBWL was greater in the IGB/pharmacotherapy group (12.6% ± 1.2 vs 9.7% ± 0.7, P = .04). 65.2% of patients achieved ≥10% TBWL at 12 months in the IGB/pharmacotherapy group, compared to 38.0% in the IGB/lifestyle group (P < .05). The proportion of patients that achieved ≥15% weight loss at 12 months was also significantly different between the IGB/pharmacotherapy and IGB/lifestyle groups (30.4% vs 20.3%, P < .05).

DISCUSSION

IGB with concomitant use of pharmacotherapy did not improve weight loss while the IGB was in place compared to IGB and lifestyle changes. However, patients receiving IGB with pharmacotherapy did have greater weight loss and diminished weight regain after balloon removal compared to those receiving just IGB and lifestyle changes.

Western diet leads to aging-related tumorigenesis via activation of the inflammatory, UPR, and EMT pathways

Among the principal causative factors for the development of complications related to aging is a diet rich in fats and sugars, also known as the Western diet. This diet advocates numerous changes that might increase the susceptibility to initiate cancer and/or to create a tissue microenvironment more conducive to the growth of malignant cells, thus favoring the progression of cancer and metastasis. Hypercaloric diets in general lead to oxidative stress generating reactive oxygen species and induce endoplasmic reticulum stress. Our results demonstrate that mice bearing tumors fed with a Western diet presented bigger tumor mass with increased insulin sensitivity in these tissues. Several markers of insulin signaling, such as AKT phosphorylation and mTOR pathway, are promoted in tumors of Western diet-fed animals. This process is associated with increased macrophage infiltration, activation of unfolded protein response pathway, and initiation of epithelial-mesenchymal transition (EMT) process in these tumor tissues. Summing up, we propose that the Western diet accelerates the aging-related processes favoring tumor development.

Endoscopic sleeve gastroplasty plus liraglutide versus endoscopic sleeve gastroplasty alone for weight loss

BACKGROUND AND AIMS

Endoscopic sleeve gastroplasty (ESG) has been shown to be effective for inducing weight loss. The efficacy of liraglutide, a glucagon-like peptide-1 agonist, to augment weight loss after ESG is unknown. This study aims to evaluate the efficacy of ESG and liraglutide (ESG-L) compared with ESG alone.

METHODS

This was a retrospective study of prospectively collected data from patients undergoing ESG at 3 outpatient clinics in Brazil between November 2017 and July 2018. Liraglutide was offered to all patients 5 months after ESG. Patients who opted to take liraglutide (ESG-L) were matched 1:1 to patients who declined it (ESG). The primary outcome was percent total body weight loss (%TBWL), and percent excess weight loss (%EWL) 7 months after initiation of liraglutide (12 months after ESG). The secondary outcome was change in percent body fat 12 months after ESG. ESG technique and postprocedure follow-up were identical at all 3 sites.

RESULTS

Propensity score matching yielded 26 matched pairs. Adjusted comparisons between the 2 groups showed that patients who opted to take liraglutide had a superior mean %TBWL 7 months after initiation of liraglutide (ESG-L) compared with those who declined it (ESG) (24.72% ± 2.12% vs 20.51% ± 1.68%, respectively; P < .001). ESG-L had a statistically greater reduction in percent body fat compared with ESG (7.85% ± 1.26% vs 10.54% ± 1.88%, respectively; P < .001) at 12 months.

CONCLUSIONS

Addition of liraglutide at 5 months results in superior weight loss and improved efficacy as demonstrated by decreased body fat 12 months after ESG. Further studies are imperative to determine optimal dose, timing, and duration of liraglutide.

Isoform- and Paralog-Switching in IR-Signaling: When Diabetes Opens the Gates to Cancer

Insulin receptor (IR) and IR-related signaling defects have been shown to trigger insulin-resistance in insulin-dependent cells and ultimately to give rise to type 2 diabetes in mammalian organisms. IR expression is ubiquitous in mammalian tissues, and its over-expression is also a common finding in cancerous cells. This latter finding has been shown to associate with both a relative and absolute increase in IR isoform-A (IR-A) expression, missing 12 aa in its EC subunit corresponding to exon 11. Since IR-A is a high-affinity transducer of Insulin-like Growth Factor-II (IGF-II) signals, a growth factor is often secreted by cancer cells; such event offers a direct molecular link between IR-A/IR-B increased ratio in insulin resistance states (obesity and type 2 diabetes) and the malignant advantage provided by IGF-II to solid tumors. Nonetheless, recent findings on the biological role of isoforms for cellular signaling components suggest that the preferential expression of IR isoform-A may be part of a wider contextual isoform-expression switch in downstream regulatory factors, potentially enhancing IR-dependent oncogenic effects. The present review focuses on the role of isoform- and paralog-dependent variability in the IR and downstream cellular components playing a potential role in the modulation of the IR-A signaling related to the changes induced by insulin-resistance-linked conditions as well as to their relationship with the benign versus malignant transition in underlying solid tumors.

Adipose Tissue, Obesity and Adiponectin: Role in Endocrine Cancer Risk

Adipose tissue has been recognized as a complex organ with endocrine and metabolic roles. The excess of fat mass, as occurs during overweight and obesity states, alters the regulation of adipose tissue, contributing to the development of obesity-related disorders. In this regard, many epidemiological studies shown an association between obesity and numerous types of malignancies, comprising those linked to the endocrine system (e.g., breast, endometrial, ovarian, thyroid and prostate cancers). Multiple factors may contribute to this phenomenon, such as hyperinsulinemia, dyslipidemia, oxidative stress, inflammation, abnormal adipokines secretion and metabolism. Among adipokines, growing interest has been placed in recent years on adiponectin (APN) and on its role in carcinogenesis. APN is secreted by adipose tissue and exerts both anti-inflammatory and anti-proliferative actions. It has been demonstrated that APN is drastically decreased in obese individuals and that it can play a crucial role in tumor growth. Although literature data on the impact of APN on carcinogenesis are sometimes conflicting, the most accredited hypothesis is that it has a protective action, preventing cancer development and progression. The aim of the present review is to summarize the currently available evidence on the involvement of APN and its signaling in the etiology of cancer, focusing on endocrine malignancies.

Insulin resistance and adrenal incidentalomas: A bidirectional relationship

An adrenal incidentaloma (AI) is an adrenal mass incidentally found via a radiological modality, independent of an endocrinological investigation. In this review, we aimed to investigate the possible reasons behind the increased frequency in AI detection, especially in ageing populations. The pathophysiological effects of insulin resistance (IR), hyperinsulinemia and various anabolic pathways are analyzed. In addition, we review data from studies indicating an increased incidence of adrenal adenomas and carcinomas in patients with type 2 diabetes mellitus (T2DM). The establishment of obesity as a global epidemic, with a higher prevalence in the female than in the male population, coincide with data regarding AIs and the conditions may share a pathophysiological basis. Furthermore, we discuss the bidirectional association of AIs with obesity, insulin resistance and T2DM, especially in patients with autonomous cortisol secretion. Lastly, as per the definition of an AI, we touch upon the evolution of radiological imaging as another possible cause of the rise in prevalence of AIs, especially concerning the greater use and precision of computed tomography (CT).

The association between metabolic syndrome and bladder cancer susceptibility and prognosis: an updated comprehensive evidence synthesis of 95 observational studies involving 97,795,299 subjects

Background

The association between metabolic syndrome (MS) and bladder cancer (BC) was not fully investigated, and most primary studies and pooled analyses were only focused on certain specific components.

Objective

To further investigate this issue and obtain more precise findings, we conducted this updated evidence synthesis of published studies, which involved not only MS components but also the MS in its entirety.

Materials and methods

We searched the PubMed, EMBASE, and Web of Science databases for observational studies on the association between BC susceptibility and/or mortality, and MS and its components. We extracted data from included studies, evaluated heterogeneity, and performed meta-analytic quantitative syntheses.

Results

A total of 95 studies with 97,795,299 subjects were included in the present study. According to the results, MS significantly increased the risk of BC (risk ratio [RR]=1.11, 95% CI=1.00–1.23); diabetes significantly increased the risk of BC (RR=1.29, 95% CI=1.19–1.39) and associated with poor survival (RR=1.24, 95% CI=1.08–1.43). Excessive body weight was associated with increased susceptibility (RR=1.07, 95% CI=1.02–1.12), recurrence (RR=1.46, 95% CI=1.18–1.81), and mortality (RR=1.17, 95% CI=1.00–1.37). As indicated by cumulative meta-analysis, sample size was inadequate for the association between BC susceptibility and MS, the association between BC recurrence and excessive body weight, and the association between BC survival and diabetes. The sample size of the meta-analysis was enough to reach a stable pooled effect for other associations.

Conclusion

Diabetes and excessive body weight as components of MS are associated with increased susceptibility and poor prognosis of BC. Uncertainty remains concerning the impact of overall MS, hypertension, and dyslipidemia on BC susceptibility and prognosis, for which further investigations are needed.

Adverse glycaemic effects of cancer therapy: indications for a rational approach to cancer patients with diabetes

Diabetes and cancer are common, chronic, and potentially fatal diseases that frequently co-exist. Observational studies have reported an increased risk of cancer in patients with diabetes. Furthermore, many patients with cancer already have diabetes, or develop hyperglycaemia as a consequence of the tumor or of cancer therapies, and coexisting diabetes confers a greater risk of mortality for many malignancies. Managing oncologic patients with diabetes is often complicated, since the co-existence of diabetes and cancer poses several complex clinical questions: what level of glycaemic control to achieve, which therapy to use, how to deal with glucocorticoid therapies and artificial nutrition, how diabetes complications can affect cancer management, which drug-drug interactions should be taken into account, or even how to manage diabetes at the end of life. In the clinical setting, both at hospital and at home, there are little agreed, evidence-based guidelines on the best management and criteria upon which clinical decisions should be based. A practical solution lies in the implementation of care networks based on communication and ongoing collaboration between Oncologists, Endocrinologists, and the nursing staff, with the patient at the centre of the care process. This manuscript aims to review the current evidence on the effect of cancer therapies on glucose metabolism and to address some of the more common challenges of diabetes treatment in patients with cancer.

PPAR-γ Agonists As Antineoplastic Agents in Cancers with Dysregulated IGF Axis

It is now widely accepted that insulin resistance and compensatory hyperinsulinemia are associated to increased cancer incidence and mortality. Moreover, cancer development and progression as well as cancer resistance to traditional anticancer therapies are often linked to a deregulation/overactivation of the insulin-like growth factor (IGF) axis, which involves the autocrine/paracrine production of IGFs (IGF-I and IGF-II) and overexpression of their cognate receptors [IGF-I receptor, IGF-insulin receptor (IR), and IR]. Recently, new drugs targeting various IGF axis components have been developed. However, these drugs have several limitations including the occurrence of insulin resistance and compensatory hyperinsulinemia, which, in turn, may affect cancer cell growth and survival. Therefore, new therapeutic approaches are needed. In this regard, the pleiotropic effects of peroxisome proliferator activated receptor (PPAR)-γ agonists may have promising applications in cancer prevention and therapy. Indeed, activation of PPAR-γ by thiazolidinediones (TZDs) or other agonists may inhibit cell growth and proliferation by lowering circulating insulin and affecting key pathways of the Insulin/IGF axis, such as PI3K/mTOR, MAPK, and GSK3-β/Wnt/β-catenin cascades, which regulate cancer cell survival, cell reprogramming, and differentiation. In light of these evidences, TZDs and other PPAR-γ agonists may be exploited as potential preventive and therapeutic agents in tumors addicted to the activation of IGF axis or occurring in hyperinsulinemic patients. Unfortunately, clinical trials using PPAR-γ agonists as antineoplastic agents have reached conflicting results, possibly because they have not selected tumors with overactivated insulin/IGF-I axis or occurring in hyperinsulinemic patients. In conclusion, the use of PPAR-γ agonists in combined therapies of IGF-driven malignancies looks promising but requires future developments.

Insulin, insulin receptors, and cancer

Insulin is a major regulator of cell metabolism but, in addition, is also a growth factor. Insulin effects in target cells are mediated by the insulin receptor (IR), a transmembrane protein with enzymatic (tyrosine kinase) activity. The insulin receptor, however, is represented by a heterogeneous family of proteins, including two different IR isoforms and also hybrid receptors resulting from the IR hemireceptor combination with a hemireceptor of the cognate IGF-1 receptor. These different receptors may bind insulin and its analogs with different affinity and produce different biologic effects. Since many years, it is known that many cancer cells require insulin for optimal in vitro growth. Recent data indicate that: (1) insulin stimulates growth mainly via its own receptor and not the IGF-1 receptor; (2) in many cancer cells, the IR is overexpressed and the A isoform, which has a predominant mitogenic effect, is more represented than the B isoform. These characteristics provide a selective growth advantage to malignant cells when exposed to insulin. For this reason, all conditions of hyperinsulinemia, both endogenous (prediabetes, metabolic syndrome, obesity, type 2 diabetes before pancreas exhaustion and polycystic ovary syndrome) and exogenous (type 1 diabetes) will increase the risk of cancer. Cancer-related mortality is also increased in patients exposed to hyperinsulinemia but other factors, related to the different diseases, may also contribute. The complexity of the diseases associated with hyperinsulinemia and their therapies does not allow a precise evaluation of the cancer-promoting effect of hyperinsulinemia, but its detrimental effect on cancer incidence and mortality is well documented.

Hyperglycemia, tumorigenesis, and chronic inflammation

Hyperglycemia is the most prominent sign that characterizes diabetes. Hyperglycemia favors malignant cell growth by providing energy to cancer cells. Clinical studies also showed an increased risk of diabetes being associated with different types of cancers. In addition, poorly regulated glucose metabolism in diabetic patients is often found with increased levels of chronic inflammatory markers, e.g., interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, and emerging evidence has highlighted activation of the immune response in the progression and development of cancer cells. Therefore, uncontrolled proinflammatory responses could conceivably create a chronic inflammatory state, promoting a tumor-favorable microenvironment and potentially triggering immune overactivation and cancer growth. To further understand how hyperglycemia contributes to immune overactivation, the tumor microenvironment and the development of chronic inflammation-associated tumors may provide insights into tumor biology and immunology. This paper provides a brief introduction to hyperglycemia-associated diseases, followed by a comprehensive overview of the current findings of regulatory molecular mechanisms of glycosylation on proteoglycans in the extracellular matrix under hyperglycemic conditions. Then, the authors discuss the role of hyperglycemia in tumorigenesis (particularly in prostate, liver, colorectal, and pancreatic cancers), as well as the contribution of hyperglycemia to chronic inflammation. The authors end with a brief discussion on the future perspectives of hyperglycemia/tumorigenesis and potential applications of alternative/effective therapeutic strategies for hyperglycemia-associated cancers.

Adrenocortical tumors and insulin resistance: What is the first step?

The pathogenetic mechanisms underlying the onset of adrenocortical tumors (ACTs) are still largely unknown. Recently, more attention has been paid to the role of insulin and insulin-like growth factor (IGF) system on general tumor development and progression. Increased levels of insulin, IGF-1 and IGF-2 are associated with tumor cell growth and increased risk of cancer promotion and progression in patients with type 2 diabetes. Insulin resistance and compensatory hyperinsulinemia may play a role in adrenal tumor growth through the activation of insulin and IGF-1 receptors. Interestingly, apparently non-functioning ACTs are often associated with a high prevalence of insulin resistance and metabolic syndrome. However, it is unclear if ACT develops from a primary insulin resistance and compensatory hyperinsulinemia or if insulin resistance is only secondary to the slight cortisol hypersecretion by ACT. The aim of this review is to summarize the current evidence regarding the relationship between hyperinsulinemia and adrenocortical tumors.

Heat-induced aggregation of thylakoid membranes affect their interfacial properties

Heat treatment of thylakoid membranes induce loss of chlorophyll, reduced emulsifying capacity and reduced lipase/co-lipase inhibition capacityin vitro.

Novel Aspects Concerning the Functional Cross-Talk between the Insulin/IGF-I System and Estrogen Signaling in Cancer Cells

The insulin/IGF system plays an important role in cancer progression. Accordingly, elevated levels of circulating insulin have been associated with an increased cancer risk as well as with aggressive and metastatic cancer phenotypes. Numerous studies have documented that estrogens cooperate with the insulin/IGF system in multiple pathophysiological conditions. The biological responses to estrogens are mainly mediated by the estrogen receptors (ER)α and ERβ, which act as transcription factors; however, several studies have recently demonstrated that a member of the G protein-coupled receptors, named GPR30/G-protein estrogen receptor (GPER), is also involved in the estrogen signaling in normal and malignant cells as well as in cancer-associated fibroblasts (CAFs). In this regard, novel mechanisms linking the action of estrogens through GPER with the insulin/IGF system have been recently demonstrated. This review recapitulates the relevant aspects of this functional cross-talk between the insulin/IGF and the estrogenic GPER transduction pathways, which occurs in various cell types and may account for cancer progression.

Dietary and metabolic control of stem cell function in physiology and cancer

Organismal diet has a profound impact on tissue homeostasis and health in mammals. Adult stem cells are a keystone of tissue homeostasis that alters tissue composition by balancing self-renewal and differentiation divisions. Because somatic stem cells may respond to shifts in organismal physiology to orchestrate tissue remodeling and some cancers are understood to arise from transformed stem cells, there is a likely possibility that organismal diet, stem cell function, and cancer initiation are interconnected. Here we will explore the emerging effects of diet on nutrient-sensing pathways active in mammalian tissue stem cells and their relevance to normal and cancerous growth.

Diabetes mellitus: influences on cancer risk

Diabetes mellitus and cancer are common conditions, and their co-diagnosis in the same individual is not infrequent. The relative risks associated with type 2 diabetes are greater than twofold for hepatic, pancreatic, and endometrial cancers. The relative risk is somewhat lower, at 1.2-1.5-fold for colorectal, breast, and bladder cancers. In comparison, the relative risk of lung cancer is less than 1. The evidence for other malignancies (e.g. kidney, non-Hodgkin lymphoma) is inconclusive, whereas prostatic cancer occurs less frequently in male patients with diabetes. The potential biologic links between the two diseases are incompletely understood. Evidence from observational studies suggests that some medications used to treat hyperglycemia are associated with either increased or reduced risk of cancer. Whereas anti-diabetic drugs have a minor influence on cancer risk, drugs used to treat cancer may either cause diabetes or worsen pre-existing diabetes. If hyperinsulinemia acts as a critical link between the observed increased cancer risk and type 2 diabetes, one would predict that patients with type 1 diabetes would have a different cancer risk pattern than patients with type 2 diabetes because the former patients are exposed to lower levels of exogenous administered insulin. Obtained results showed that patients with type 1 diabetes had elevated risks of cancers of the stomach, cervix, and endometrium. Type 1 diabetes is associated with a modest excess cancer risk overall and risks of specific cancers that differ from those associated with type 2 diabetes.

Effects of honey and its mechanisms of action on the development and progression of cancer

Honey is a natural product known for its varied biological or pharmacological activities-ranging from anti-inflammatory, antioxidant, antibacterial, antihypertensive to hypoglycemic effects. This review article focuses on the role of honey in modulating the development and progression of tumors or cancers. It reviews available evidence (some of which is very recent) with regards to the antimetastatic, antiproliferative and anticancer effects of honey in various forms of cancer. These effects of honey have been thoroughly investigated in certain cancers such as breast, liver and colorectal cancer cell lines. In contrast, limited but promising data are available for other forms of cancers including prostate, bladder, endometrial, kidney, skin, cervical, oral and bone cancer cells. The article also underscores the various possible mechanisms by which honey may inhibit growth and proliferation of tumors or cancers. These include regulation of cell cycle, activation of mitochondrial pathway, induction of mitochondrial outer membrane permeabilization, induction of apoptosis, modulation of oxidative stress, amelioration of inflammation, modulation of insulin signaling and inhibition of angiogenesis. Honey is highly cytotoxic against tumor or cancer cells while it is non-cytotoxic to normal cells. The data indicate that honey can inhibit carcinogenesis by modulating the molecular processes of initiation, promotion, and progression stages. Thus, it may serve as a potential and promising anticancer agent which warrants further experimental and clinical studies.

Insulin receptor (IR) and insulin-like growth factor receptor 1 (IGF-1R) signaling systems: novel treatment strategies for cancer

Insulin and insulin-like growth factor (IGF) signaling system, commonly known for fine-tuning numerous biological processes, has lately made its mark as a much sought-after therapeutic targets for diabetes and cancer. These receptors make an attractive anticancer target owing to their overexpression in variety of cancer especially in prostate and breast cancer. Inhibitors of IGF signaling were subjected to clinical cancer trials with the main objective to confirm the effectiveness of these receptors as a therapeutic target. However, the results that these trials produced proved to be disappointing as the role played by the cross talk between IGF and insulin receptor (IR) signaling pathways at the receptor level or at downstream signaling level became more lucid. Therapeutic strategy for IGF-1R and IR inhibition mainly encompasses three main approaches namely receptor blockade with monoclonal antibodies, tyrosine kinase inhibition (ATP antagonist and non-ATP antagonist), and ligand neutralization via monoclonal antibodies targeted to ligand or recombinant IGF-binding proteins. Other drug-discovery approaches are employed to target IGF-1R, and IR includes antisense oligonucleotides and recombinant IGF-binding proteins. However, therapies with monoclonal antibodies and tyrosine kinase inhibition targeting the IGF-1R are not evidenced to be satisfactory as expected. Factors that are duly held responsible for the unsuccessfulness of these therapies include (a) the existence of the IR isoform A overexpressed on a variety of cancers, enhancing the mitogenic signals to the nucleus leading to the endorsement of cell growth, (b) IGF-1R and IR that form hybrid receptors sensitive to the stimulation of all three IGF axis ligands, and (c) IGF-1R and IR that also have the potential to form hybrid receptors with other tyrosine kinase to potentiate the cellular transformation, tumorigenesis, and tumor vascularization. This mini review is a concerted effort to explore and fathom the well-recognized roles of the IRA signaling system in human cancer phenotype and the main strategies that have been so far evaluated to target the IR and IGF-1R.

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.

Worldwide increasing incidence of thyroid cancer: update on epidemiology and risk factors

Background. In the last decades, thyroid cancer incidence has continuously and sharply increased all over the world. This review analyzes the possible reasons of this increase. Summary. Many experts believe that the increased incidence of thyroid cancer is apparent, because of the increased detection of small cancers in the preclinical stage. However, a true increase is also possible, as suggested by the observation that large tumors have also increased and gender differences and birth cohort effects are present. Moreover, thyroid cancer mortality, in spite of earlier diagnosis and better treatment, has not decreased but is rather increasing. Therefore, some environmental carcinogens in the industrialized lifestyle may have specifically affected the thyroid. Among potential carcinogens, the increased exposure to medical radiations is the most likely risk factor. Other factors specific for the thyroid like increased iodine intake and increased prevalence of chronic autoimmune thyroiditis cannot be excluded, while other factors like the increasing prevalence of obesity are not specific for the thyroid. Conclusions. The increased incidence of thyroid cancer is most likely due to a combination of an apparent increase due to more sensitive diagnostic procedures and of a true increase, a possible consequence of increased population exposure to radiation and to other still unrecognized carcinogens.

CYP2W1, CYP4F11 and CYP8A1 polymorphisms and interaction of CYP2W1 genotypes with risk factors in Mexican women with breast cancer

Breast cancer (BCa) is the leading type of cancer in Mexican women. Genetic factors, such as single nucleotide polymorphisms (SNP) of P450 system, have been reported in BCa. In this report, and for the first time in the literature, we analyzed the rs3735684 (7021 G>A), rs11553651 (15016 G>T) and rs56195291 (60020 C>G) polymorphisms in the CYP2W1, 4F11 and 8A1 genes in patients with BCa and in healthy Mexican women to identify a potential association between these polymorphisms and BCa risk. Patients and controls were used for polymorphism analysis using an allelic discrimination assay with TaqMan probes and confirmed by DNA sequencing. Links with clinic-pathological characteristics were also analyzed. Statistical analysis was performed using the standard χ2 or Fisher exact test statistic. No significant differences were observed in the distributions of CYP2W1 (OR 8.6, 95%CI 0.43-172.5 P>0.05; OR 2.0, 95%CI 0.76-5.4, P>0.05) and CYP4F11 (OR 0.3, 95%CI 0.01-8.4 P>0.05) genotypes between the patients and controls. Only the CYP8A1 CC genotype was detected in patients with BCa and the controls. All polymorphism frequencies were in Hardy-Weinberg Equilibrium (HWE) in the controls (P>0.05). We found a significant association between BCa risk and smoking, use of oral contraceptives or hormonal replacement therapy (HRT), obesity, hyperglycemia, chronic diseases, family history of cancer and menopausal status in the population studied (P<0.05). Tobacco, oral contraceptive or HRT, chronic diseases and obesity or overweight were strongly associated with almost eight, thirty-five, nine and five-fold increased risk for BCa. Tobaco, obesity and hyperglycemia significantly increased the risk of BCa in the patients carrying variant genotypes of CYP2W1 (P<0.05). These results indicate that the CYP2W1 rs3735684, CYP4F11 rs11553651 and CYP8A1 rs56195291 SNPs are not a key risk factor for BCa in Mexican women. This study did not detect an association between the CYP2W1, 4F11 and 8A1 genes polymorphisms and BCa risk in a Mexican population. However, some clinico-pathological risk factors interact with CYP2W1 genotypes and modifies susceptibility to BCa.

Examining the relationship between diet-induced acidosis and cancer

Increased cancer risk is associated with select dietary factors. Dietary lifestyles can alter systemic acid-base balance over time. Acidogenic diets, which are typically high in animal protein and salt and low in fruits and vegetables, can lead to a sub-clinical or low-grade state of metabolic acidosis. The relationship between diet and cancer risk prompts questions about the role of acidosis in the initiation and progression of cancer. Cancer is triggered by genetic and epigenetic perturbations in the normal cell, but it has become clear that microenvironmental and systemic factors exert modifying effects on cancer cell development. While there are no studies showing a direct link between diet-induced acidosis and cancer, acid-base disequilibrium has been shown to modulate molecular activity including adrenal glucocorticoid, insulin growth factor (IGF-1), and adipocyte cytokine signaling, dysregulated cellular metabolism, and osteoclast activation, which may serve as intermediary or downstream effectors of carcinogenesis or tumor promotion. In short, diet-induced acidosis may influence molecular activities at the cellular level that promote carcinogenesis or tumor progression. This review defines the relationship between dietary lifestyle and acid-base balance and discusses the potential consequences of diet-induced acidosis and cancer occurrence or progression.

Intragastric balloon in association with lifestyle and/or pharmacotherapy in the long-term management of obesity

BACKGROUND

Intragastric balloon (BioEnterics Intragastric Balloon, BIB®) or pharmacotherapy are possible options for the treatment of obese patients when traditional approaches have failed. The aim of our study was to compare in obese patients the effect on weight loss and metabolic changes of lifestyle modifications associated with either BIB or pharmacotherapy or the two treatments in sequence as a maintenance strategy for weight loss.

METHODS

Fifty obese patients were recruited and randomly assigned to lifestyle modifications combined with either BIB for 6 months (n = 30) or sibutramine (pharmacotherapy group) for 1 year (n = 20). After BIB removal, patients were randomly assigned to either correct lifestyle (BIB/lifestyle) or lifestyle plus pharmacotherapy (BIB/pharmacotherapy).

RESULTS

At 6 months, patients treated with BIB lost significantly (P < 0.05) more weight (percent of initial weight lost, %IWL = 14.5 ± 1.2; percent of excess BMI lost, %EBL = 37.7 ± 3.2) than patients who received pharmacological treatment (%IWL = 9.1 ± 1.5, %EBL = 25.3 ± 4.1). At 1 year, the weight lost was significantly (P < 0.05) greater in patients treated with either BIB/pharmacotherapy (%IWL = 15.8 ± 2.3%, %EBL = 41.3 ± 6.7%) or BIB/lifestyle (%IWL = 14.3 ± 2.7, %EBL = 34.9 ± 6.5%) in respect to pharmacotherapy group (%IWL = 8.0 ± 1.4%, %EBL = 22.1 ± 3.9%). Moreover, patients treated sequentially with BIB/lifestyle or BIB/pharmacotherapy showed a significant (P < 0.05) improvement in insulin sensitivity and triglycerides levels.

CONCLUSIONS

BIB represents an efficacious long-term obesity treatment when supplemental strategies, as lifestyle modifications or pharmacotherapy, are established for weight maintenance after its removal.

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.

The role of metformin in the management of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disorder worldwide. Its prevalence ranges 10–24% in the general population, reaching 60–95% and 28–55% in obese and diabetic patients, respectively. Although the etiology of NAFLD is still unclear, several lines of evidences have indicated a pathogenetic role of insulin resistance in this disorder. This concept has stimulated several clinical studies where antidiabetic drugs, such as insulin sensitizers including metformin, have been evaluated in insulin-resistant, NAFLD patients. These studies indicate that metformin might be of benefit in the treatment of NAFLD, also in nondiabetic patients, when associated to hypocaloric diet and weight control. However, the heterogeneity of these studies still prevents us from reaching firm conclusions about treatment guidelines. Moreover, metformin could have beneficial tissue-specific effects in NAFLD patients irrespective of its effects as insulin sensitizer.

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.

Diabetes and cancer: is diabetes causally related to cancer?

Diabetes mellitus is a serious and growing health problem worldwide and is associated with severe acute and chronic complications. Moreover, epidemiologic evidence suggests that people with diabetes are at significantly higher risk for many forms of cancer. Several studies indicate an association between diabetes and the risk of liver, pancreas, endometrium, colon/rectum, breast, and bladder cancer. Mortality is also moderately increased in subjects with diabetes. Common risk factors such as age, obesity, physical inactivity and smoking may contribute to increased cancer risk in diabetic patients. Hyperinsulinemia most likely favors cancer in diabetic patients as insulin is a growth factor with pre-eminent metabolic as well as mitogenic effects, and its action in malignant cells is favored by mechanisms acting at both the receptor and post-receptor level. The effect of diabetes treatment drugs, aside from metformin, on cancer is not conclusive. In order to fight the perfect storm of diabetes and cancer, strategies to promote primary prevention and early detection of these conditions are urgently needed.

Insulin receptor isoforms and insulin-like growth factor receptor in human follicular cell precursors from papillary thyroid cancer and normal thyroid

CONTEXT

Factors involved in the biology of normal and cancer stem/precursor cells from the thyroid are unknown. Thyroid cancer cells are responsive to insulin and IGF-I and IGF-II and often overexpress the insulin receptor (IR) and the IGF-I receptor (IGF-IR).

OBJECTIVE

We investigated the role of IR isoforms (IR-A and IR-B), IGF-IR, and their ligands in thyroid follicular cell precursors both normal and malignant.

DESIGN

We established cultures of follicular cell precursors as thyrospheres from three papillary thyroid cancers and the corresponding nonaffected tissues. The expression of IR, IGF-IR, and their ligands was evaluated by quantitative RT-PCR and, in one case, also by Western blot. The effects of insulin and IGFs on thyrosphere growth and self-renewal were evaluated.

RESULTS

Thyrospheres were characterized by the expression of stem cell markers and low/absent thyroid specific markers. Thyrospheres from normal tissue, but not from cancer tissue, could be induced to differentiate. Both IR isoforms, IGF-IR, IGF-I and IGF-II, were expressed at high levels in thyrospheres and markedly decreased in differentiating cells. IR-A was the predominant isoform in thyrospheres, especially from cancer, while IR-B was predominant in differentiating cells. Cancer thyrosphere growth was stimulated by insulin and IGFs.

CONCLUSIONS

Our data suggest that IR isoforms and IGF-IR play a role in the biology of follicular thyroid precursors. Cell differentiation is associated with marked changes in the expression of these receptors and cognate ligands. These data may provide insight for future differentiation therapies in thyroid cancer.

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.

Insulin analogues differently activate insulin receptor isoforms and post-receptor signalling

AIMS/HYPOTHESIS

Five insulin analogues, with modified insulin-like molecular structures, are currently approved for treating diabetic patients. They activate cell signalling and biological responses via insulin receptor isoforms (IR-A and IR-B), each having specific characteristics for eliciting cell responses. The molecular and biological effects of these analogues on receptor isoforms in comparison to native insulin are not well defined, and their effects on the IGF1 receptor (IGF1R) are controversial. The characterisation of these effects was the aim of the present study.

METHODS

Short-acting (insulin lispro [B28Lys,B29Pro human insulin], insulin aspart [B28Asp human insulin], insulin glulisine [B3Lys,B29Glu human insulin]) and long-acting (insulin glargine [A21Gly,B31Arg,B32Arg human insulin], insulin detemir [B29Lys(epsilon-tetradecanoyl),desB30 human insulin]) insulin analogues were studied in three engineered cell models (R(-), IGF1R-deprived mouse fibroblasts transfected with either only human IR-A or IR-B or IGF1R). Receptor binding and phosphorylation, AKT and extracellular signal-regulated kinase (ERK) activation, cell proliferation and colony formation were evaluated after exposing the cells to each analogue and were compared with insulin, IGF1 and the carcinogenic analogue B10Asp.

RESULTS

All short-acting insulin analogues produced molecular and biological effects similar but not identical to those of insulin. Relative to insulin, long-acting analogues more strongly activated the ERK pathway via both IR-A and IGF1R as well as increased cell proliferation. At the concentration tested, no analogue (except B10Asp via IR-A) had increased transforming activity.

CONCLUSIONS/INTERPRETATION

Cell models that permit comparisons of the activity of insulin to that of insulin analogues via each receptor individually indicate that only minor differences exist between insulin and short-acting analogues. By contrast, long-acting analogues activate the mitogenic signalling pathway more effectively than insulin and cause increased cell proliferation.

Enhanced tumorigenesis of forestomach tumors induced by N-Methyl-N'-nitro-N-nitrosoguanidine in rats with hypoinsulinemic diabetes

Hyperinsulinemia and hyperglycemia in prediabetic and diabetic patients are thought to increase the risk of developing neoplasms because insulin is a growth factor with pre-eminent metabolic but also mitogenic effects. To determine the effect of hypoinsulinemic diabetic conditions on carcinogenesis, we examined N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced forestomach carcinogenesis in hypoinsulinemic diabetic WBN/Kob rats aged about 45 weeks (DM) compared with non-diabetic younger WBN/Kob rats (C1), non-diabetic Wistar rats age-matched to DM (C2), and non-diabetic Wistar rats age-matched to C1 (C3). All rats were treated with MNNG by gavage and were killed at 40 weeks after dosing. Various-sized tumors were disseminated throughout the forestomach of all rats, and the ratio of the area of tumors to the whole forestomach area was 23.3% in the DM group and was higher than in the C1-3 (4.2-14.3%) groups. The incidence of carcinoma was much higher in the DM group (36.8%) than in the C1-3 (7.1-16.7%) groups, and the incidence of papilloma was also significantly higher in the DM group (84.2%) than in the C1-3 (28.5-50.0%) groups. The average thickness of the squamous epithelium in the non-neoplastic mucosa was significantly greater in the DM group (50.8 mum) than in the C1-3 (29.6-37.9 microm) groups. Immunohistochemically, the Ki-67-positive index in the non-tumorous mucosa of the DM group (42.0%) was significantly higher than that of the C1-3 groups (18.8-33.3%). These results suggest that prolonged hyperglycemic conditions without hyperinsulinemia enhance tumorigenesis of MNNG-induced tumors by enhanced proliferative activity of the squamous epithelium in the rat forestomach.

Insulin receptor functionally enhances multistage tumor progression and conveys intrinsic resistance to IGF-1R targeted therapy

The type 1 insulin-like growth factor receptor (IGF-1R) tyrosine kinase is an important mediator of the protumorigenic effects of IGF-I/II, and inhibitors of IGF-1R signaling are currently being tested in clinical cancer trials aiming to assess the utility of this receptor as a therapeutic target. Despite mounting evidence that the highly homologous insulin receptor (IR) can also convey protumorigenic signals, its direct role in cancer progression has not been genetically defined in vivo, and it remains unclear whether such a role for IR signaling could compromise the efficacy of selective IGF-1R targeting strategies. A transgenic mouse model of pancreatic neuroendocrine carcinogenesis engages the IGF signaling pathway, as revealed by its dependence on IGF-II and by accelerated malignant progression upon IGF-1R overexpression. Surprisingly, preclinical trials with an inhibitory monoclonal antibody to IGF-1R did not significantly impact tumor growth, prompting us to investigate the involvement of IR. The levels of IR were found to be significantly up-regulated during multistep progression from hyperplastic lesions to islet tumors. Its functional involvement was revealed by genetic disruption of the IR gene in the oncogene-expressing pancreatic beta cells, which resulted in reduced tumor burden accompanied by increased apoptosis. Notably, the IR knockout tumors now exhibited sensitivity to anti-IGF-1R therapy; similarly, high IR to IGF-1R ratios demonstrably conveyed resistance to IGF-1R inhibition in human breast cancer cells. The results predict that elevated IR signaling before and after treatment will respectively manifest intrinsic and adaptive resistance to anti-IGF-1R therapies.

Obesity management--an opportunity for cancer prevention

There is increasing evidence of an association between obesity and the development, morbidity and mortality of cancers of the colorectum, (post menopausal) breast, endometrium, kidney, pancreas and oesophagus. In addition to obesity per se, waist circumference is now emerging as a clear indicator of disease risk. Weight gain during adult life also appears to increase risk for breast and colon cancers. Major causative factors which are influenced by excess energy storage include hormones involved in metabolic control (insulin and leptin), cell growth (IGF-I and IGF-binding proteins) and reproduction (steroids and leptin). In addition, raised oestrogens are likely to contribute to the greater risk of breast and endometrial cancers. In cancer survivors, there are also strong indications that being overweight increases the risk for recurrence and reduces the likelihood of survival. Whilst there are no robust data testing the effect of weight loss on recurrence, current guidance highlights that normal weight, overweight and obese patients should avoid weight gain and that a modest weight loss of 5-10% is likely to have significant health benefits. Two studies have now reported long-term effects of obesity surgery on cancer risk (in addition to reducing metabolic disorders and type 2 diabetes). It is becoming increasingly clear that multi-disciplinary groups (including surgeons) are needed to identify, monitor and evaluate programmes for both obesity prevention and management.

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.

Modulating pancreatic lipase activity with galactolipids: effects of emulsion interfacial composition

It is widely known that the interfacial quality of lipid emulsion droplets influences the rate and extent of lipolysis. The aim of this work was to investigate the effect of two galactolipids, monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), adsorbed at the interface on in vitro digestibility of olive oil by porcine pancreatic lipase. The experiments were performed under simulated duodenal conditions in the presence of phosphatidylcholine (lecithin) and bile salts. It was found that emulsions prepared with DGDG had a longer lag phase prior to lipase activation with a decrease in lipolysis rate. In contrast, no inhibitory effect on lipase kinetics was observed in emulsions prepared with MGDG. We postulated that the larger headgroup and more tightly packed molecular organization of DGDG at the interface gave rise to steric hindrance that retarded colipase and lipase adsorption onto the substrate surfaces and hence delayed and reduced lipolysis. It was noted that the lag phase and lipolysis rate strongly depended on the DGDG/lecithin molar ratio in the systems: the higher the molar ratio, the longer the lag phase followed by a reduced lipolysis rate. The ability of DGDG to inhibit bile salt adsorption/displacement was also investigated. The results showed that bile salts did not completely displace DGDG from the interface, explaining the reason why DGDG still possessed inhibitory activity even in the presence of bile salts at a physiological relevant concentration. The results provide interesting insights into the influence of the galactolipid headgroup and lecithin on the emulsion interfacial quality which in turn regulates the lipolysis. The findings potentially could lead to the production of generic foods and drugs designed for regulating dietary fat absorption in the prevention and treatment of obesity and related disorders.

PPAR-γ agonists and their effects on IGF-I receptor signaling: Implications for cancer

It is now well established that the development and progression of a variety of human malignancies are associated with dysregulated activity of the insulin-like growth factor (IGF) system. In this regard, promising drugs have been developed to target the IGF-I receptor or its ligands. These therapies are limited by the development of insulin resistance and compensatory hyperinsulinemia, which in turn, may stimulate cancer growth. Novel therapeutic approaches are, therefore, required. Synthetic PPAR-γ agonists, such as thiazolidinediones (TZDs), are drugs universally used as antidiabetic agents in patients with type 2 diabetes. In addition of acting as insulin sensitizers, PPAR-γ agonists mediate in vitro and in vivo pleiotropic anticancer effects. At least some of these effects appear to be linked with the downregulation of the IGF system, which is induced by the cross-talk of PPAR-γ agonists with multiple components of the IGF system signaling. As hyperinsulinemia is an emerging cancer risk factor, the insulin lowering action of PPAR-γ agonists may be expected to be also beneficial to reduce cancer development and/or progression. In light of these evidences, TZDs or other PPAR-γ agonists may be exploited in those tumors "addicted" to the IGF signaling and/or in tumors occurring in hyperinsulinemic patients.

IGF and insulin receptor signaling in breast cancer

Major molecular abnormalities in breast cancer include the deregulation of several components of the IGF system. It is well recognized that the epithelial breast cancer cells commonly overexpress the IGF-I receptor while IGF-II is expressed by the tumor stroma. In view to the fact that the IGF-IR has mitogenic, pro-invasive and anti-apoptotic effects and mediates resistance to a variety of anti-cancer therapies, breast cancer is expected to be a candidate to therapeutic approaches aimed to inhibit the IGF-IR. However, there is increasing awareness that IGF system in cancer undergoes signal diversification by various mechanisms. One of these mechanisms is the aberrant expression of insulin receptor (IR) isoform A (IR-A), which is a high affinity receptor for both insulin and IGF-II, in breast cancer cells. Moreover, overexpression of both IGF-IR and IR-A in breast cancer cells, leads to overexpression of hybrid IR/IGF-IR receptors (HRs) as well. Upon binding to IGF-II, both IR-A and HRs may activate unique signaling patterns, which predominantly mediate proliferative effects. A better understanding of IGF system signal diversification in breast cancer has important implications for cancer prevention measures, which should include control of insulin resistance and associated hyperinsulinemia. Moreover, in addition to the IGF-IR, both IR-A and HRs should be also considered as molecular targets for anti-cancer therapies.

The role of insulin receptors and IGF-I receptors in cancer and other diseases

There is evidence, both in vitro and in vivo, that receptor tyrosine kinases play a key role in the formation and progression of human cancer. In particular, the insulin-like growth factor receptor (IGF-IR), a tyrosine kinase receptor for IGF-I and IGF-II, has been well documented in cell culture, animal studies, and humans to play a role in malignant transformation, progression, protection from apoptosis, and metastasis. In addition, the hormone insulin (which is very closely related to the IGFs) and its tyrosine kinase receptor (the IR, which is very closely related to the IGR-IR) have been documented both in vitro and in vivo to play a key role in cancer biology. Indeed, several epidemiological studies have shown that insulin resistance status, characterized by hyperinsulinaemia, is associated with an increased risk for a number of malignancies, including carcinomas of the breast, prostate, colon and kidney. Recent data have elucidated some molecular mechanisms by which IR is involved in cancer. IR is over-expressed in several human malignancies. Interestingly, one of the two IR isoform (IR-A) is especially over-expressed in cancer. IR-A is the IR foetal isoform and has the peculiar characteristic to bind not only insulin but also IGF-II. In addition, the IR contributes to formation of hybrid receptors with the IGF-IR (HR). By binding to hybrid receptors, insulin may stimulate specific IGF-IR signalling pathways. Over-expression of IR-A is, therefore, a major mechanism of IGF system over-activation in cancer. In this respect, IR-A isoform and hybrid receptors should be regarded as potential molecular targets, in addition to IGF-IR, for novel anti-cancer therapy. These findings may have important implications for both the prevention and treatment of common human malignancies. They underline the concept that hyperinsulinaemia, associated with insulin resistance and obesity, should be treated by changes in life style and/or pharmacological approaches to avoid an increased risk for cancer. Moreover, native insulin and insulin analogue administration should be carefully evaluated in terms of the possible increase in cancer risk.

To treat or not to treat: comparison of different criteria used to determine whether weight loss is to be recommended

Background

Excess body fat is a major risk factor for disease primarily due to its endocrine activity. In recent years several criteria have been introduced to evaluate this factor. Nevertheless, treatment need is currently assessed only on the basis of an individual's Body Mass Index (BMI), calculated as body weight (in kg) divided by height in m². The aim of our study was to determine whether application of the BMI, compared to adiposity-based criteria, results in underestimation of the number of subjects needing lifestyle intervention.

Methods

We compared treatment need based on BMI classification with four adiposity-based criteria: percentage body fat (%BF), considered both alone and in relation to metabolic syndrome risk (MS), waist circumference (WC), as an index of abdominal fat, and Body Fat Mass Index (BFMI, calculated as fat mass in kg divided by height in m²) in 63 volunteers (23 men and 40 women, aged 20 – 65 years).

Results

According to the classification based on BMI, 6.3% of subjects were underweight, 52.4% were normal weight, 30.2% were overweight, and 11.1% were obese. Agreement between the BMI categories and the other classification criteria categories varied; the most notable discrepancy emerged in the underweight and overweight categories. BMI compared to almost all of the other adiposity-based criteria, identified a lower percentage of subjects for whom treatment would be recommended. In particular, the proportion of subjects for whom clinicians would strongly recommend weight loss on the basis of their BMI (11.1%) was significantly lower than those identified according to WC (25.4%, p = 0.004), %BF (28.6%, p = 0.003), and MS (33.9%, p = 0.002).

Conclusion

The use of the BMI alone, as opposed to an assessment based on body composition, to identify individuals needing lifestyle intervention may lead to unfortunate misclassifications. Population-specific data on the relationships between body composition, morbidity, and mortality are needed to improve the diagnosis and treatment of at-risk individuals.

Physical activity as primary prevention to address cancer disparities

OBJECTIVE

To review the research literature on physical activity (PA) intervention trials, with an emphasis on underserved populations.

DATA SOURCE

Research studies, review articles, and books.

CONCLUSION

PA intervention studies have generally shown statistically significant but modest outcomes. Comprehensive intervention designs combining individual-level and physical environmental changes have posted the largest effect sizes, and emerging models are incorporating sociocultural and organizational environmental changes with promising results. Research including or targeting underserved populations poses unique challenges at each stage of the intervention process: design, recruitment, implementation, and evaluation. Synthesis of evidence-based approaches to address these challenges is presented.

IMPLICATIONS FOR NURSING PRACTICE

Promoting PA in underserved communities is essential in improving population-level cancer outcomes. Additional resources are becoming available to nursing researchers and practitioners to aid in the conduct of PA intervention in understudied groups.

Leptin augments proliferation of breast cancer cells via transactivation of HER2

Excessive fat mass is a risk factor for postmenopausal breast cancer. Leptin, a fat cell-derived peptide hormone, elicits a growth-stimulating effect in breast cancer cells with leptin receptor expression, although the leptin-induced signal in malignant cells is not fully understood. Here, we found that exogenous leptin induced tyrosine phosphorylation of HER2 in SKBR3 cells, which showed marked overexpression of HER2. Phosphorylation of HER2 was detected at 2 min and continued up to 120 min after the start of stimulation. Leptin-induced HER2 phosphorylation was partially reduced by an epidermal growth factor receptor inhibitor, AG1478, or a Janus-activated kinase inhibitor, AG490. Leptin also induced phosphorylation of extracellular signal-regulated kinase 1/2, which was mostly abrogated by a HER2 tyrosine kinase inhibitor, AG825. In a proliferation assay, addition of 500 ng/mL leptin increased the proliferation of SKBR3, which was totally inhibited by AG825. Collectively, our data suggest that leptin can transactivate HER2 through both epidermal growth factor receptor and Janus-activated kinase 2 activation, which can cause the growth of breast cancer cells with HER2 overexpression.