Hormone responsive human breast cancer in long-term tissue culture: effect of insulin

Value of C-Reactive Protein-Triglyceride Glucose Index in Predicting Cancer Mortality in the General Population: Results from National Health and Nutrition Examination Survey

BACKGROUND

Cancer is one of the leading causes of death. The current work aims to investigate the association between C-reactive protein-triglyceride glucose index (CTI) and the risk of incident cancer mortality and to evaluate the usefulness of CTI to refine the risk stratification of cancer mortality.

METHODS

The study enrolled 19,957 subjects from American National Health and Nutrition Examination Survey. CTI was defined as 0.412*Ln(CRP) + ln[T.G. (mg/dL) × FPG (mg/dL)/2]. Cox regression was performed to investigate the association.

RESULTS

During a follow-up of 215417.52 person-years, 736 subjects died due to malignant tumors, and the incidence of cancer mortality was 3.42 per 1,000 person-years. Kaplan-Meier curve revealed that the fourth quartile group had the lowest cancer mortality-free rate (Log-Rank p < 0.001). After full adjustment, each SD increase of CTI cast a 32.7% additional risk of incident cancer mortality. Furthermore, cancer mortality risk elevated proportionally with the increase of CTI. Finally, ROC and reclassification analyses supported the usefulness of CTI in improving the risk stratification of incident cancer mortality.

CONCLUSION

The study revealed a significant association between CTI and cancer mortality risk, suggesting the value of CTI in improving the risk stratification of incident cancer mortality. KEY MESAGESC-reactive protein-triglyceride glucose index (CTI) is positively associated with cancer mortality risk in the general population.The association was linear in the whole range of CTI.CTI could improve the risk prediction of cancer mortality in the general population.

A body shape index (ABSI) is associated inversely with post-menopausal progesterone-receptor-negative breast cancer risk in a large European cohort

BACKGROUND

Associations of body shape with breast cancer risk, independent of body size, are unclear because waist and hip circumferences are correlated strongly positively with body mass index (BMI).

METHODS

We evaluated body shape with the allometric "a body shape index" (ABSI) and hip index (HI), which compare waist and hip circumferences, correspondingly, among individuals with the same weight and height. We examined associations of ABSI, HI, and BMI (per one standard deviation increment) with breast cancer overall, and according to menopausal status at baseline, age at diagnosis, and oestrogen and progesterone receptor status (ER+/-PR+/-) in multivariable Cox proportional hazards models using data from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.

RESULTS

During a mean follow-up of 14.0 years, 9011 incident breast cancers were diagnosed among 218,276 women. Although there was little evidence for association of ABSI with breast cancer overall (hazard ratio HR = 0.984; 95% confidence interval: 0.961-1.007), we found borderline inverse associations for post-menopausal women (HR = 0.971; 0.942-1.000; n = 5268 cases) and breast cancers diagnosed at age ≥ 55 years (HR = 0.976; 0.951-1.002; n = 7043) and clear inverse associations for ER + PR- subtypes (HR = 0.894; 0.822-0.971; n = 726) and ER-PR- subtypes (HR = 0.906; 0.835-0.983 n = 759). There were no material associations with HI. BMI was associated strongly positively with breast cancer overall (HR = 1.074; 1.049-1.098), for post-menopausal women (HR = 1.117; 1.085-1.150), for cancers diagnosed at age ≥ 55 years (HR = 1.104; 1.076-1.132), and for ER + PR + subtypes (HR = 1.122; 1.080-1.165; n = 3101), but not for PR- subtypes.

CONCLUSIONS

In the EPIC cohort, abdominal obesity evaluated with ABSI was not associated with breast cancer risk overall but was associated inversely with the risk of post-menopausal PR- breast cancer. Our findings require validation in other cohorts and with a larger number of PR- breast cancer cases.

Circulating Insulin-Like Growth Factor 1-Related Biomarkers and Risk of Lethal Prostate Cancer

Background

Experimental and epidemiologic evidence supports the role of circulating insulin-like growth factor-1 (IGF-1) levels with the risk of prostate cancer. Most circulating IGF-1 is bound to specific binding proteins, and only about 5% circulates in a free form. We explored the relation of free IGF-1 and other components of the IGF system with lethal prostate cancer.

Methods

Using prospectively collected samples, we undertook a nested case-only analysis among 434 men with lethal prostate cancer and 524 men with indolent, nonlethal prostate cancer in the Physicians’ Health Study and the Health Professionals Follow-up Study. Prediagnostic plasma samples were assayed for free IGF-1 and total IGF-1, acid labile subunit, pregnancy-associated plasma protein A (PAPP-A), and intact and total IGF binding protein 4. We estimated odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for the associations between IGF-1–related biomarkers and lethal prostate cancer using unconditional logistic regression models adjusted for age, height, and body mass index.

Results

Men in the highest quartile of PAPP-A levels had 42% higher odds of lethal prostate cancer (pooled adjusted OR = 1.42, 95% CI = 1.04 to 1.92) compared with men in the lowest 3 quartiles. There were no statistically significant differences in the other plasma analytes. The positive association between PAPP-A and lethal prostate cancer was present among men with intact PTEN but not among those with tumor PTEN loss (2-sided P_interaction = .001).

Conclusions

Our study provides suggestive evidence that among men who later develop prostate cancer, higher plasma PAPP-A levels measured prior to diagnosis are associated with increased risk of lethal compared with indolent disease.

Insulin Resistance and Cancer: In Search for a Causal Link

Insulin resistance (IR) is a condition which refers to individuals whose cells and tissues become insensitive to the peptide hormone, insulin. Over the recent years, a wealth of data has made it clear that a synergistic relationship exists between IR, type 2 diabetes mellitus, and cancer. Although the underlying mechanism(s) for this association remain unclear, it is well established that hyperinsulinemia, a hallmark of IR, may play a role in tumorigenesis. On the other hand, IR is strongly associated with visceral adiposity dysfunction and systemic inflammation, two conditions which favor the establishment of a pro-tumorigenic environment. Similarly, epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNA, in IR states, have been often associated with tumorigenesis in numerous types of human cancer. In addition to these observations, it is also broadly accepted that gut microbiota may play an intriguing role in the development of IR-related diseases, including type 2 diabetes and cancer, whereas potential chemopreventive properties have been attributed to some of the most commonly used antidiabetic medications. Herein we provide a concise overview of the most recent literature in this field and discuss how different but interrelated molecular pathways may impact on tumor development.

A molecular link between diabetes and breast cancer: Therapeutic potential of repurposing incretin-based therapies for breast cancer

Female breast cancer recently surpassed lung cancer and became the most commonly diagnosed cancer worldwide. As per the recent data from WHO, breast cancer accounts for one out of every 8 cancer cases diagnosed among an estimated 2.3 million new cancer cases. Breast cancer is the most prevailing cancer type among women causing the highest number of cancer-related mortality. It has been estimated that in 2020, 68,5000 women died due to this disease. Breast cancers have varying degrees of molecular heterogeneity; therefore, they are divided into various molecular clinical sub types. Recent reports suggest that type 2 diabetes (one of the common chronic diseases worldwide) is linked to the higher incidence, accelerated progression, and aggressiveness of different cancers; especially breast cancer. Breast cancer is hormone-dependent in nature and has a cross-talk with metabolism. A number of antidiabetic therapies are known to exert beneficial effects on various types of cancers, including breast cancer. However, only a few reports are available on the role of incretin-based antidiabetic therapies in cancer as a whole and in breast cancer in particular. The present review sheds light on the potential of incretin based therapies on breast cancer and explores the plausible underlying mechanisms. Additionally, we have also discussed the sub types of breast cancer as well as the intricate relationship between diabetes and breast cancer.

Clinical Implication of Metformin in Relation to Diabetes Mellitus and Ovarian Cancer

Since multiple reports established an association between diabetes mellitus and various cancers, emerging studies have surfaced to understand the effects of metformin as an anti-cancer agent. Although there was previous, but conflicting evidence, of a relationship between diabetes and ovarian cancer (OvCa), recent studies have supported this association. The mechanism of cancer development in patients with diabetes is likely to involve hyperglycemia, hyperinsulinemia, chronic inflammation, reactive oxygen species, regulation of cellular homeostasis, and activation of various pathways that lead to tumor cell proliferation. Preclinical evidence indicating that metformin, a medication commonly used to treat type 2 diabetes mellitus, may protect against OvCa. Metformin exerts anti-cancer properties by activating the MAPK pathway, inhibiting the PI3K/AKT/mTOR pathway, increasing tumor suppressor genes, inducing G2/M cycle arrest, and various other processes. Several studies have shown the efficacy of metformin as an adjunct with standard chemotherapeutic agents due to its synergistic effects on OvCa cells. This review highlights the epidemiologic evidence supporting a link between diabetes and OvCa, the fundamental molecular mechanism underlying carcinogenesis in patients with diabetes, the anti-cancer effects of metformin, and the need for further clinical investigations on combination therapies with metformin and standard chemotherapeutic agents for OvCa.

PAM (PIK3/AKT/mTOR) signaling in glia: potential contributions to brain tumors in aging

Despite a growing proportion of aged individuals at risk for developing cancer in the brain, the prognosis for these conditions remains abnormally poor due to limited knowledge of underlying mechanisms and minimal treatment options. While cancer metabolism in other organs is commonly associated with upregulated glycolysis (i.e. Warburg effect) and hyperactivation of PIK3/AKT/mTOR (PAM) pathways, the unique bioenergetic demands of the central nervous system may interact with these oncogenic processes to promote tumor progression in aging. Specifically, constitutive glycolysis and PIK3/AKT/mTOR signaling in glia may be dysregulated by age-dependent alterations in neurometabolic demands, ultimately contributing to pathological processes otherwise associated with PIK3/AKT/mTOR induction (e.g. cell cycle entry, impaired autophagy, dysregulated inflammation). Although several limitations to this theoretical model exist, the consideration of aberrant PIK3/AKT/mTOR signaling in glia during aging elucidates several therapeutic opportunities for brain tumors, including non-pharmacological interventions.

Metformin and an insulin/IGF-1 receptor inhibitor are synergistic in blocking growth of triple-negative breast cancer

PURPOSE

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with poor survival outcomes. Metformin has been shown to have antitumor effects by lowering serum levels of the mitogen insulin and having pleiotropic effects on cancer cell signaling pathways. BMS-754807 is a potent and reversible inhibitor of both insulin-like growth factor 1 receptor (IGF-1R) and insulin receptor (IR). Both drugs have been reported to have some efficacy in TNBC. However, it is unclear whether the combination of the two drugs is more effective than single drug treatment in TNBC.

METHODS

We treated a panel of TNBC cell lines with metformin and BMS-754807 alone and in combination and tested cell viability using MTS assays. We used the CompuSyn software to analyze for additivity, synergism, or antagonism. We also examined the molecular mechanism by performing reverse phase protein assay (RPPA) to detect the candidate pathways altered by single drugs and the drug combination and used Western blotting to verify and expand the findings.

RESULTS

The combination of metformin and BMS-754807 showed synergy in 11 out of 13 TNBC cell lines tested (85%). RPPA analysis detected significant alterations by the drug combination of multiple proteins known to regulate cell cycle and tumor growth. In particular, the drug combination significantly increased levels of total and phosphorylated forms of the cell cycle inhibitor p27^Kip1 and decreased the level of the p27^Kip1 E3 ligase SCF^Skp2.

CONCLUSIONS

We conclude that the combination of metformin and BMS-754807 is more effective than either drug alone in inhibiting cell proliferation in the majority of TNBC cell lines, and that one important mechanism may be suppression of SCF^Skp2 and subsequent stabilization of the cell cycle inhibitor p27^Kip1. This combination treatment may represent an effective targeted therapy for a significant subset of TNBC cases and should be further evaluated.

Reproductive hormones during pubertal transition in girls with transient Thelarche

CONTEXT

Transient thelarche (TT), that is, the appearance, regression and subsequent reappearance of breast buds, is a frequent phenomenon, but little is known about pubertal transition in these girls.

OBJECTIVE

To describe pubertal progression, growth, genotypes, reproductive hormones and growth factors in girls with TT compared to those who do not present TT (non-TT).

DESIGN

Retrospective analysis of a longitudinal population-based study.

PATIENTS OR OTHER PARTICIPANTS

Girls (n = 508) of the Chilean Growth and Obesity cohort.

MEASUREMENTS

Pubertal progression, reproductive hormones, follicle stimulating hormone (FSH) beta subunit/FSH receptor gene single nucleotide polymorphisms and growth.

RESULTS

Thirty-seven girls (7.3%) were presented TT. These girls entered puberty by pubarche more frequently (51%) than girls with normal progression (non-TT; n = 471; 23%, P = .005). Girls with TT who were under 8 years old had lower androgens, anti-Müllerian hormone (AMH), luteinizing hormone (LH) and oestradiol (all P < .05) than older girls with TT. At the time of Tanner breast stage 2 (B2), girls with TT had higher androgens, LH, FSH, IGF1, LH, insulin and oestradiol (P < .01) than at the time of TT. TT girls were older at B2 (10.3 ± 1.1 vs. 9.2 ± 1.2 years, P < .001) and menarche (12.3 ± 0.8 vs. 12.0 ± 1.0 years, P = .040) than their counterparts (non-TT). No differences in anthropometric variables or FSHB/FSHR genotypes were detected.

CONCLUSION

Transient thelarche is a frequent phenomenon that does not appear to be mediated by hypothalamic-pituitary-gonadal axis activation or by adiposity. Hormonal differences between earlier TT and later TT suggest that their mechanisms are different.

Insulin-PI3K signalling: an evolutionarily insulated metabolic driver of cancer

Cancer is driven by incremental changes that accumulate, eventually leading to oncogenic transformation. Although genetic alterations dominate the way cancer biologists think about oncogenesis, growing evidence suggests that systemic factors (for example, insulin, oestrogen and inflammatory cytokines) and their intracellular pathways activate oncogenic signals and contribute to targetable phenotypes. Systemic factors can have a critical role in both tumour initiation and therapeutic responses as increasingly targeted and personalized therapeutic regimens are used to treat patients with cancer. The endocrine system controls cell growth and metabolism by providing extracellular cues that integrate systemic nutrient status with cellular activities such as proliferation and survival via the production of metabolites and hormones such as insulin. When insulin binds to its receptor, it initiates a sequence of phosphorylation events that lead to activation of the catalytic activity of phosphoinositide 3-kinase (PI3K), a lipid kinase that coordinates the intake and utilization of glucose, and mTOR, a kinase downstream of PI3K that stimulates transcription and translation. When chronically activated, the PI3K pathway can drive malignant transformation. Here, we discuss the insulin-PI3K signalling cascade and emphasize its roles in normal cells (including coordinating cell metabolism and growth), highlighting the features of this network that make it ideal for co-option by cancer cells. Furthermore, we discuss how this signalling network can affect therapeutic responses and how novel metabolic-based strategies might enhance treatment efficacy for cancer.

RLIP controls receptor-ligand signaling by regulating clathrin-dependent endocytosis

RLIP (Ral-interacting protein) is a multifunctional protein that couples ATP hydrolysis with the movement of substances. Its primary function appears to be in the plasma membrane, where it catalyzes the ATP-dependent efflux of glutathione-conjugates (GS-Es), as well as un-metabolized drugs and toxins. In the plasma membrane, its interaction with the clathrin adaptor protein AP2 localizes it to endocytic vesicle, where its GS-E-stimulated ATPase and transport activity are required for clathrin-dependent endocytosis (CDE). CDE is an essential mechanism for internalizing ligand-receptor complexes that signal proliferation (EGF, insulin, IGF1), apoptosis (TNFα, TRAIL, Fas-L), and differentiation and morphogenesis (TGFβ, WNT, Notch, SHH). Aberrant functioning of these pathways appears crucial for most cancer cells to evade apoptosis, invade surrounding tissues, and metastasize. Internalization of receptor-ligand complexes by CDE begins a sequence of events that can terminate, initiate, or modulate downstream signaling; the consequences of signaling through these downstream pathways may be inherently different in cancer and normal cells, a view supported by numerous basic and clinical observations. In this review, we will discuss the GS-E transport activity of RLIP, which determines the rate of ligand endocytosis, and how the inhibition and/or depletion of RLIP globally disrupts in ligand-receptor signaling.

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.

Antitumor effect of insulin-like growth factor-1 receptor inhibition in head and neck squamous cell carcinoma

OBJECTIVES

The insulin-like growth factor-1 receptor (IGF1R) has been implicated in therapeutic resistance in head and neck squamous cell carcinoma (HNSCC), and small molecule tyrosine kinase inhibitors (TKIs) of IGF1R activity may have anticancer activity. Therefore, the relationship between survival and IGF1R expression was assessed for oral cavity (OC) cancer, and the antitumor effects of two IGF1R-TKIs, OSI-906 and BMS-754807, were evaluated in HNSCC cell lines in vitro.

METHODS

Clinical outcome data and tissue microarray immunohistochemistry were used to generate IGF1R expression-specific survival curves. Immunoblot, alamarBlue proliferation assay, trypan blue exclusion viability test, clonogenic assay, flow cytometry, and reverse phase protein array (RPPA) were used to evaluate in vitro responses to IGF1R-TKIs.

RESULTS

For patients with stage III/IV OCSCC, higher IGF1R expression was associated with poorer overall 5-year survival (P = 0.029). Both BMS-754807 and OSI-906 caused dose-dependent inhibition of IGF1R and Akt phosphorylation and inhibited proliferation; BMS-754807 was more potent than OSI-906. Both drugs reduced HNSCC cell viability; only OSI-906 was able to eliminate all viable cells at 10 μM. The two drugs similarly inhibited clonogenic cell survival. At 1 μM, only BMS-754807 caused a fourfold increase in the basal apoptotic rate. RPPA demonstrated broad effects of both drugs on canonical IGF1R signaling pathways and also inhibition of human epidermal growth factor receptor-3 (HER3), Src, paxillin, and ezrin phosphorylation.

CONCLUSION

OSI-906 and BMS-754807 inhibit IGF1R activity in HNSCC cell lines with reduction in prosurvival and proliferative signaling and with concomitant antiproliferative and proapoptotic effects. Such antagonists may have utility as adjuvants to existing therapies for HNSCC.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:1470-1478, 2020.

Dietary calories and lipids synergistically shape adipose tissue cellularity during postnatal growth

Objective

The susceptibility to abdominal obesity and the metabolic syndrome is determined to a substantial extent during childhood and adolescence, when key adipose tissue characteristics are established. Although the general impact of postnatal nutrition is well known, it is not clear how specific dietary components drive adipose tissue growth and how this relates to the risk of metabolic dysfunction in adulthood.

Methods

Adipose tissue growth including cell proliferation was analyzed in juvenile mice upon dietary manipulation with in vivo nucleotide labeling. The proliferative response of progenitors to specific fatty acids was assayed in primary cultures. Long-term metabolic consequences were assessed through transient dietary manipulation post-weaning with a second obesogenic challenge in adulthood.

Results

Dietary lipids stimulated adipose tissue progenitor cell proliferation in juvenile mice independently of excess caloric intake and calorie-dependent adipocyte hypertrophy. Excess calories increased mitogenic IGF-1 levels systemically, whereas palmitoleic acid was able to enhance the sensitivity of progenitors to IGF-1, resulting in synergistic stimulation of proliferation. Early transient consumption of excess lipids promoted hyperplastic adipose tissue expansion in response to a second dietary challenge in adulthood and this correlated with abdominal obesity and hyperinsulinemia.

Conclusions

Dietary lipids and calories differentially and synergistically drive adipose tissue proliferative growth and the programming of the metabolic syndrome in childhood.

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Dietary fat accelerates adipose tissue progenitor proliferation in juvenile mice.

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Lipid-mediated proliferation is independent of excess calorie intake.

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Excess calories elevate IGF-1 levels and adipocyte hypertrophy.

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Palmitoleic acid enhances the proliferative response of progenitors to IGF-1.

•

Lipids and calories in childhood program features of the adult metabolic syndrome.

miR-29a regulated ER-positive breast cancer cell growth and invasion and is involved in the insulin signaling pathway

Increasing amounts of evidence show that insulin can activate different insulin signaling pathways to promote breast cancer growth and invasion. miR-29a plays crucial roles in decreasing glucose-stimulated insulin secretion, as well as in regulating breast cancer cell proliferation and EMT. However, the mechanism responsible for the regulatory effects of miR-29a on breast cancer growth and invasion and the relationship between these effects and insulin signaling remains unclear. Herein, we showed that human insulin increased miR-29a expression in ER-positive breast cancer cells and that miR-29a facilitated the ability of insulin to promote breast cancer cell proliferation and migration. We found that miR-29a-induced cell proliferation and metastasis acceleration occurred primarily through ERK phosphorylation. The IGF-1R is the upstream target gene of miR-29a, while CDC42 and p85α are the downstream target genes of miR-29a. These results have provided us with information regarding the molecular mechanisms by which hyperinsulinemia promotes breast cancer occurrence and development and thus leads to a poor prognosis in breast cancer patients and indicate that miR-29a plays an important role in breast cancer development and invasion.

Deciphering metabolic rewiring in breast cancer subtypes

Metabolic reprogramming, an emerging hallmark of cancer, is observed in breast cancer. Breast cancer cells rewire their cellular metabolism to meet the demands of survival, proliferation, and invasion. However, breast cancer is a heterogeneous disease, and metabolic rewiring is not uniform. Each subtype of breast cancer displays distinct metabolic alterations. Here, we focus on unique metabolic reprogramming associated with subtypes of breast cancer, as well as common features. Therapeutic opportunities based on subtype-specific metabolic alterations are also discussed. Through this discussion, we aim to provide insight into subtype-specific metabolic rewiring and vulnerabilities that have the potential to better guide therapy and improve outcomes for patients.

Insulin in combination with cisplatin induces the apoptosis of ovarian cancer cells via p53 and JNK activation

Drug resistance is an obstacle to effective treatment of ovarian cancer. There have been substantial evidences supporting the association between diabetes and the sensitivity to chemotherapy. Insulin (INS) is believed to be the strongest, most lasting hypoglycemic drug. Therefore, the present study aimed to elucidate whether insulin could facilitate the anti‑proliferative activities of cisplatin (cis‑diamminedichloroplatinum, DDP) in the A2780 ovarian cancer cell line. The inhibitory effects of DPP with/without INS on the growth of A2780 cells was measured by MTT assay. The cell cycle stages and levels of apoptosis were determined by flow cytometry. The amounts of signaling elements involved in the regulation of were examined using western blotting and reverse transcription‑quantitative polymerase chain reaction analysis. The results indicated that INS pre‑treatment enhanced the inhibitory effect of DDP on the proliferation of A2780 cells, and facilitated the apoptosis induced by DDP. INS‑DDP treatment led to a marked decrease in the percentage of G0/G1 phase cells, but a corresponding increase in the proportion of S phase cells. Furthermore, A2780 cells pretreated with INS followed by DDP upregulated the protein expression level of phosphorylated c‑Jun N‑terminal kinase (JNK), which resulted in a substantial increase in the expression levels of p53 mRNA and protein, compared with DDP administration alone. In conclusion, the combination of INS and DDP facilitated the apoptosis of A2780 cells, which may be associated with the activation of the JNK signaling pathway and consequently the involvement of p53 at both mRNA and protein expression levels. These results may be useful in furthering our understanding of the mechanisms involved in the chemotherapeutic treatment of ovarian cancer.

Insulin resistance in vascular endothelial cells promotes intestinal tumour formation

The risk of several cancers, including colorectal cancer, is increased in patients with obesity and type 2 diabetes, conditions characterized by hyperinsulinemia and insulin resistance. Because hyperinsulinemia itself is an independent risk factor for cancer development, we examined tissue-specific insulin action in intestinal tumor formation. In vitro, insulin increased proliferation of primary cultures of intestinal tumor epithelial cells from Apc^Min/+ mice by over 2-fold. Surprisingly, targeted deletion of insulin receptors in intestinal epithelial cells in Apc^Min/+ mice did not change intestinal tumor number or size distribution on either a low or high-fat diet. We therefore asked whether cells in the tumor stroma might explain the association between tumor formation and insulin resistance. To this end, we generated Apc^Min/+ mice with loss of insulin receptors in vascular endothelial cells. Strikingly, these mice had 42% more intestinal tumors than controls, no change in tumor angiogenesis, but increased expression of vascular cell adhesion molecule-1 (VCAM-1) in primary culture of tumor endothelial cells. Insulin decreased VCAM-1 expression and leukocyte adhesion in quiescent tumor endothelial cells with intact insulin receptors and partly prevented increases in VCAM-1 and leukocyte adhesion after treatment with tumor necrosis factor-α. Knockout of insulin receptors in endothelial cells also increased leukocyte adhesion in mesenteric venules and increased the frequency of neutrophils in tumors. We conclude that although insulin is mitogenic for intestinal tumor cells in vitro, its action on tumor cells in vivo is via signals from the tumor microenvironment. Insulin resistance in tumor endothelial cells produces an activated, proinflammatory state that promotes tumorigenesis. Improvement of endothelial dysfunction may reduce colorectal cancer risk in patients with obesity and type 2 diabetes.

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

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

The GH/IGF-1 axis in a critical period early in life determines cellular DNA repair capacity by altering transcriptional regulation of DNA repair-related genes: implications for the developmental origins of cancer

Experimental, clinical, and epidemiological findings support the concept of developmental origins of health and disease (DOHAD), suggesting that early-life hormonal influences during a sensitive period around adolescence have a powerful impact on cancer morbidity later in life. The endocrine changes that occur during puberty are highly conserved across mammalian species and include dramatic increases in circulating GH and IGF-1 levels. Importantly, patients with developmental IGF-1 deficiency due to GH insensitivity (Laron syndrome) do not develop cancer during aging. Rodents with developmental GH/IGF-1 deficiency also exhibit significantly decreased cancer incidence at old age, marked resistance to chemically induced carcinogenesis, and cellular resistance to genotoxic stressors. Early-life treatment of GH/IGF-1-deficient mice and rats with GH reverses the cancer resistance phenotype; however, the underlying molecular mechanisms remain elusive. The present study was designed to test the hypothesis that developmental GH/IGF-1 status impacts cellular DNA repair mechanisms. To achieve that goal, we assessed repair of γ-irradiation-induced DNA damage (single-cell gel electrophoresis/comet assay) and basal and post-irradiation expression of DNA repair-related genes (qPCR) in primary fibroblasts derived from control rats, Lewis dwarf rats (a model of developmental GH/IGF-1 deficiency), and GH-replete dwarf rats (GH administered beginning at 5 weeks of age, for 30 days). We found that developmental GH/IGF-1 deficiency resulted in persisting increases in cellular DNA repair capacity and upregulation of several DNA repair-related genes (e.g., Gadd45a, Bbc3). Peripubertal GH treatment reversed the radiation resistance phenotype. Fibroblasts of GH/IGF-1-deficient Snell dwarf mice also exhibited improved DNA repair capacity, showing that the persisting influence of peripubertal GH/IGF-1 status is not species-dependent. Collectively, GH/IGF-1 levels during a critical period during early life determine cellular DNA repair capacity in rodents, presumably by transcriptional control of genes involved in DNA repair. Because lifestyle factors (e.g., nutrition and childhood obesity) cause huge variation in peripubertal GH/IGF-1 levels in children, further studies are warranted to determine their persisting influence on cellular cancer resistance pathways.

Obesity and Cancer: An Angiogenic and Inflammatory Link

With the current epidemic of obesity, a large number of patients diagnosed with cancer are overweight or obese. Importantly, this excess body weight is associated with tumor progression and poor prognosis. The mechanisms for this worse outcome, however, remain poorly understood. We review here the epidemiological evidence for the association between obesity and cancer, and discuss potential mechanisms focusing on angiogenesis and inflammation. In particular, we will discuss how the dysfunctional angiogenesis and inflammation occurring in adipose tissue in obesity may promote tumor progression, resistance to chemotherapy, and targeted therapies such as anti-angiogenic and immune therapies. Better understanding of how obesity fuels tumor progression and therapy resistance is essential to improve the current standard of care and the clinical outcome of cancer patients. To this end, we will discuss how an anti-diabetic drug such as metformin can overcome these adverse effects of obesity on the progression and treatment resistance of tumors.

Co-Managing Patients with Type 1 Diabetes and Cancer

The life expectancy of people with type 1 diabetes is improving and now approaches that of those without diabetes. As this population ages, a growing number will be diagnosed with and treated for cancer. Cancer treatments can drastically affect insulin requirement and glycemic control through multiple mechanisms including high doses of glucocorticoids and targeted therapies that directly interfere with cellular pathways involved in the action of insulin. Patients with cancer frequently also have alterations in gastrointestinal motility or appetite and require supplemental enteral or parenteral nutrition. Few studies have evaluated these patients directly, but data on patients with and without diabetes suggest that glycemic control may play a larger role in cancer outcomes than is often recognized. Collaboration between the treating oncologist and diabetologist allows people with diabetes to receive the most effective therapies for their cancers without undue risk of hypoglycemia or adverse outcomes due to hyperglycemia.

Insulin glargine use and breast cancer risk: Associations with cumulative exposure

BACKGROUND

This study was aimed to assess the risk of breast cancer associated with exposure to insulin glargine in women with type 2 diabetes and evaluate whether the pattern of risk concurs with the hypothesized trend of an increase in risk with longer duration of use, taking into account previous cumulative exposure to other types of insulin.

METHODS

We performed a restrospective cohort study (2002-2013) in the Clinical Practice Research Datalink among adult female patients with a first ever insulin prescription (n = 12 468). Time-dependent exposure measures were used to assess associations with duration of use of: (1) other insulin types before glargine was first prescribed (i.e. among switchers); and (2) of glargine during follow-up. Analyses were performed separately for insulin-naïve glargine users and patients switched to glargine. Cox proportional hazards models were used to derive p-trends, hazard ratios (HR) and 95% confidence intervals (CI) for breast cancer associated with glargine use.

RESULTS

During 66 151 person years, 186 breast cancer cases occurred; 76 in glargine users (3.0/1000 years) and 110 in users of other insulins (2.7/1000 years). Among insulin-naïve women, no association with cumulative glargine use was observed (p-trend = 0.91), even after ≥5 years (HR = 1.06, 95% CI 0.48-2.33). Among switchers, a linear trend with years of prior exposure to other insulins was found (p-trend = 0.02). An increased risk was observed in glargine users with extensive (>3 years) past exposure to other insulins (HR = 3.17, 95% CI 1.28-7.84). A non-significant trend with cumulative glargine exposure was found among switchers (p-trend = 0.24).

CONCLUSIONS

Exposure to glargine was not associated with an increased breast cancer risk in insulin-naïve patients. Exposure to other insulins prior to the start of glargine appears to be relevant when studying breast cancer risk associated with glargine use.

YAP/TAZ regulates the insulin signaling via IRS1/2 in endometrial cancer

Insulin resistance (IR) is an important mechanism of pathogenesis of endometrial cancer (EC) and explains the pathogenic mechanism of high risk factors including Obesity BMI (body mass index), Type 2 Diabetes Mellitus, PCOS and so on. Relieving IR or inhibiting the function of insulin could be one of the potential therapeutic strategies for EC, which is a PI3K-driven disease. PI3K/Akt are the central mediators for insulin/IGF1 signaling, however, the involvement of HIPPO pathway co-activators, YAP and TAZ, in insulin resistance remains to be elucidated. In the present study, we analyzed the clinical and biological data of EC patients from TCGA and observed a correlation between insulin resistance and EC. By comparing the expression level of IRS1/2 in obese vs non-obese patients, we found that the most important insulin resistance relative (IRR) genes are the contributing factors to IR. Interestingly, IRS1/2 was correlated positively with YAP/TAZ in EC patients. Knockdown of YAP/TAZ by specific siRNA inhibited the phosphorylation of IRS1 while increased the phosphorylation of IGFR1, the inhibitor of insulin signaling. Treating EC with siYAP/TAZ, YAP inhibitor Verteporfin or metformin alone only partially inhibited the function of insulin and IGF1. However, combination of siYAP/TAZ with metformin could completely inhibit the effects of insulin. Thus, our study demonstrated a novel function of YAP and TAZ in the insulin resistance via IRS1/2 in endometrial cancer. Our study also provided the rationale for the potential therapeutic treatment of EC with the combination of inhibiting YAP/TAZ and metformin.

Regulation of Stearoyl Coenzyme A Desaturase 1 Gene Promoter in Bovine Mammary Cells

Stearoyl-Coenzyme A desaturase 1 (SCD1) belongs to the fatty acid family of desaturases. In lactating ruminants, the SCD1 protein is highly expressed in the mammary gland and is relevant for the fatty acid composition of milk and dairy products. Bovine mammary epithelial cells (BME-UV1), cultured in vitro, have been proposed as a model to reproduce the biology of the mammary gland. The present study was designed to investigate the responsiveness of bovine SCD1 promoter to serum, insulin, oleic acid, and NFY transcription factor in BME-UV1 cells. A luciferase-based reporter assay was used to monitor the transcriptional activity of the SCD1 promoter region in BME-UV1 cells treated or not with insulin and/or oleic acid. The level of endogenous SCD1 mRNA was evaluated by Real time PCR. Insulin (20 ng/mL) induced a 2.0 to 2.5-fold increase of SCD1 promoter activity. Additionally, the effect of insulin was inhibited by oleic acid, serum components, and NFY enforced expression. Serum and NFY showed no synergistic or additive effect on SCD1 promoter activity suggesting that they repress SCD1 transcription through the same responsive element.

Insulin-mediated signaling promotes proliferation and survival of glioblastoma through Akt activation

BACKGROUND

Metabolic complications such as obesity, hyperglycemia, and type 2 diabetes are associated with poor outcomes in patients with glioblastoma. To control peritumoral edema, use of chronic high-dose steroids in glioblastoma patients is common, which can result in de novo diabetic symptoms. These metabolic complications may affect tumors via profound mechanisms, including activation of insulin receptor (InsR) and the related insulin-like growth factor 1 receptor (IGF1R) in malignant cells.

METHODS

In the present study, we assessed expression of InsR in glioblastoma surgical specimens and glioblastoma response to insulin at physiologically relevant concentrations. We further determined whether genetic or pharmacological targeting of InsR affected oncogenic functions of glioblastoma in vitro and in vivo.

RESULTS

We showed that InsR was commonly expressed in glioblastoma surgical specimens and xenograft tumor lines, with mitogenic isoform-A predominating. Insulin at physiologically relevant concentrations promoted glioblastoma cell growth and survival, potentially via Akt activation. Depletion of InsR impaired cellular functions and repressed orthotopic tumor growth. The absence of InsR compromised downstream Akt activity, but yet stimulated IGF1R expression. Targeting both InsR and IGF1R with dual kinase inhibitors resulted in effective blockade of downstream signaling, loss of cell viability, and repression of xenograft tumor growth.

CONCLUSIONS

Taken together, our work suggests that glioblastoma is sensitive to the mitogenic functions of insulin, thus significant insulin exposure imposes risks to glioblastoma patients. Additionally, dual inhibition of InsR and IGF1R exhibits promise for treating glioblastoma.

Crosstalk with insulin and dependence on PI3K/Akt/mTOR rather than MAPK pathways in upregulation of basal growth following long-term oestrogen deprivation in three human breast cancer cell lines

BACKGROUND

MCF-7, T-47-D, ZR-75-1 human breast cancer cell lines are dependent on oestrogen for growth but can adapt to grow during long-term oestrogen deprivation. This serves as a model for identification of therapeutic targets in endocrine-resistant breast cancer.

METHODS

An overlooked complication of this model is that it involves more than non-addition of oestrogen, and inadequate attention has been given to separating molecular events associated with each of the culture manipulations.

RESULTS

Insulin and oestradiol were shown to protect MCF-7 cells against upregulation of basal growth, demonstrating a crosstalk in the growth adaptation process. Increased phosphorylation of p44/42MAPK and c-Raf reflected removal of insulin from the medium and proliferation of all three cell lines was inhibited to a lesser extent by PD98059 and U0126 following long-term oestrogen/insulin withdrawal, demonstrating a reduced dependence on the MAPK pathway. By contrast, long-term oestrogen/insulin deprivation did not alter levels of phosphorylated Akt and did not alter the dose-response of growth inhibition with LY294002 in any of the three cell lines. The IGF1R inhibitor picropodophyllin inhibited growth of all MCF-7 cells but only in the long-term oestrogen/insulin-deprived cells was this paralleled by reduction in phosphorylated p70S6K, a downstream target of mTOR. Long-term oestrogen/insulin-deprived MCF-7 cells had higher levels of phosphorylated p70S6K and developed increased sensitivity to growth inhibition by rapamycin.

CONCLUSIONS

The greater sensitivity to growth inhibition by rapamycin in all three cell lines following long-term oestrogen/insulin deprivation suggests rapamycin-based therapies might be more effective in breast cancers with acquired oestrogen resistance.

Diabetes and its link with cancer: providing the fuel and spark to launch an aggressive growth regime

Diabetes is a disease involving metabolic derangements in multiple organs. While the spectrum of diabetic complications has been known for years, recent evidence suggests that diabetes could also contribute to the initiation and propagation of certain cancers. The mechanism(s) underlying this relationship are not completely resolved but likely involve changes in hormone and nutrient levels, as well as activation of inflammatory and stress-related pathways. Interestingly, some of the drugs used clinically to treat diabetes also appear to have antitumour effects, further highlighting the interaction between these two conditions. In this contribution we review recent literature on this emerging relationship and explore the potential mechanisms that may promote cancer in diabetic patients.

The association between type 2 diabetes mellitus and women cancer: the epidemiological evidences and putative mechanisms

Type 2 diabetes mellitus (T2DM), a chronic disease increasing rapidly worldwide, is well established as an important risk factor for various types of cancer. Although many factors impact the development of T2DM and cancer including sex, age, ethnicity, obesity, diet, physical activity levels, and environmental exposure, many epidemiological and experimental studies are gradually contributing to knowledge regarding the interrelationship between DM and cancer. The insulin resistance, hyperinsulinemia, and chronic inflammation associated with diabetes mellitus are all associated strongly with cancer. The changes in bioavailable ovarian steroid hormone that occur in diabetes mellitus (the increasing levels of estrogen and androgen and the decreasing level of progesterone) are also considered potentially carcinogenic conditions for the breast, endometrium, and ovaries in women. In addition, the interaction among insulin, insulin-like growth factors (IGFs), and ovarian steroid hormones, such as estrogen and progesterone, could act synergistically during cancer development. Here, we review the cancer-related mechanisms in T2DM, the epidemiological evidence linking T2DM and cancers in women, and the role of antidiabetic medication in these cancers.

The role of the insulin-like growth factor-1 system in breast cancer

IGF-1 is a potent mitogen of major importance in the mammary gland. IGF-1 binding to the cognate receptor, IGF-1R, triggers a signaling cascade leading to proliferative and anti-apoptotic events. Although many of the relevant molecular pathways and intracellular cascades remain to be elucidated, a growing body of evidence points to the important role of the IGF-1 system in breast cancer development, progression and metastasis. IGF-1 is a point of convergence for major signaling pathways implicated in breast cancer growth. In this review, we provide an overview and concise update on the function and regulation of IGF-1 as well as the role it plays in breast malignancies.

Effects of metformin on retinoblastoma growth in vitro and in vivo

Recent studies suggest that the anti-diabetic drug metformin may reduce the risk of cancer and have anti-proliferative effects for some but not all cancers. In this study, we examined the effects of metformin on human retinoblastoma cell proliferation in vitro and in vivo. Two different human retinoblastoma cell lines (Y79, WERI) were treated with metformin in vitro and xenografts of Y79 cells were established in nu/nu immune-deficient mice and used to assess the effects of pharmacological levels of metformin in vivo. Metformin inhibited proliferation of the retinoblastoma cells in vitro. Similar to other studies, high concentrations of metformin (mM) blocked the cell cycle in G0‑G1, indicated by a strong decrease of G1 cyclins, especially cyclin D, cyclin-dependent kinases (4 and 6), and flow cytometry assessment of the cell cycle. This was associated with activation of AMPK, inhibition of the mTOR pathways and autophagy marker LC3B. However, metformin failed to suppress growth of xenografted tumors of Y79 human retinoblastoma cells in nu/nu mice, even when treated with a maximally tolerated dose level achieved in human patients. In conclusion, suprapharmacological levels (mM) of metformin, well above those tolerated in vivo, inhibited the proliferation of retinoblastoma cells in vitro. However, physiological levels of metformin, such as seen in the clinical setting, did not affect the growth of retinoblastoma cells in vitro or in vivo. This suggests that the potential beneficial effects of metformin seen in epidemiological studies may be limited to specific tumor types or be related to indirect effects/mechanisms not observed under acute laboratory conditions.

Use of metformin and survival of diabetic women with breast cancer

Objective: This study was set out to determine whether metformin use influences survival in breast cancer patients treated with antidiabetic drugs as compared to non-users.

Research Design and Methods: We used data from the Danish national registries (1996-2008) to identify adult female patients diagnosed with breast cancer who were prescribed antidiabetic medication. We performed multivariate Cox-proportional hazard regression to assess all-cause and breast cancer-specific mortality risks associated with metformin exposure. In a secondary analysis, we stratified use of metformin according to the cumulative number of prescriptions.

Results: Of the 1058 breast cancer patients 349 died during follow-up, with breast cancer listed as the primary cause of death for 152 cases. Compared to non-use, current metformin treatment was associated with a significant reduction in overall mortality (adjusted HR 0.74, 95% CI, 0.58-0.96). For breast cancer-specific mortality, a non-significant risk reduction (adjusted HR 0.88, 95% CI, 0.59-1.29) was observed, which became significant after stratification according to cumulative number of prescriptions. An increased risk of both overall and breast cancer-specific mortality was observed in the first 12 months after discontinuation of metformin.

Conclusions: We observed a nonsignificant reduction in breast cancer-specific mortality associated with metformin exposure among breast cancer patients treated with antidiabetic drugs. However, our findings suggest that long-term metformin use may have a beneficial effect on survival in patients with breast cancer. Further confirmation of these findings is needed.

Lipid Signaling in Tumorigenesis

Lipids are important cellular building blocks and components of signaling cascades. Deregulation of lipid metabolism or signaling is frequently linked to a variety of human diseases such as diabetes, cardiovascular diseases, and cancer. It is widely believed that lipid molecules or their metabolic products are involved in tumorigenic inflammation and thus, lipids are implicated as significant contributors or even primary triggers of tumorigenesis. Lipids are believed to directly or indirectly activate growth promoting signals such as those involving LPA, insulin, IGF-1 and EGF to promote cancer cell growth. Cellular levels of certain lipids, including sphingosine-1-phosphate and ceramide, maintain a delicate balance between cell death and survival and alterations in their levels lead to unfavorable consequences including tumorigenesis. This article provides an overview of current knowledge that implicates lipids in tumorigenesis and explores the potential mechanisms that support a positive link between obesity and cancer.

Targeting receptor tyrosine kinases in HER2-negative breast cancer

PURPOSE OF REVIEW

The targeting of receptor tyrosine kinases (RTKs) has been a major area for breast cancer therapy, exemplified by the targeting of HER2-amplified breast cancer.

RECENT FINDINGS

We review the data on the activation of RTKs in HER2-negative breast cancer, and discuss the clinical translational challenge of identifying cancers that are reliant on a specific kinase for growth and survival. Substantial evidence suggests that subsets of breast cancer may be reliant on specific kinases, and that this could be exploited therapeutically. The heterogeneity of breast cancer, however, and the potential for adaptive switching between RTKs after inhibition of a single RTK, present challenges to targeting individual RTKs in the clinic

SUMMARY

Targeting of RTKs in HER2-negative breast cancer presents a major therapeutic opportunity in breast cancer, although robust selection strategies will be required to identify cancers with activation of specific RTKs if this potential is to be realized.

Clinical pathological characteristics and prognostic analysis of diabetic women with luminal subtype breast cancer

This study selected luminal-type breast cancer patients as the study subjects. The patients were divided into groups according to the presence of diabetes and the types of medication used, and the patients' clinicopathological characteristics and prognostic indicators were explored. A total of 5,785 patients with luminal-type breast cancer admitted to Tianjin Medical University Cancer Institute and Hospital between January 2002 and December 2006 were selected as the study subjects. The subjects included 680 breast cancer patients with diabetes and 5,105 breast cancer patients without diabetes. The patients were divided into Luminal A, Luminal B (high ki67), and Luminal B (her-2/neu+) subtypes. Each subtype was further divided into a metformin group, a non-metformin group, and a nondiabetic group. The research indicators included breast cancer mortality, age, body mass index (BMI), amenorrhea, the presence of cardiovascular and cerebrovascular disease, pathological stage, pathological type, lymph node involvement, vessel carcinoma embolus, and the chemotherapy and endocrine regimen. A Kaplan-Meier analysis was conducted to analyze the differences in breast cancer mortality rates among the groups. The Cox proportional hazard model was adopted to detect independent factors related to prognosis. Kaplan-Meier univariate analysis showed that for the Luminal A, Luminal B (high ki67), and Luminal B (her-2/neu+) subtypes, the cancer-specific mortality rates differed significantly among the metformin, non-metformin, and nondiabetic groups. The 5-year survival rates were 94%, 82%, and 91% (P = 0.002); 93.5%, 81%, and 89% (P < 0.001); and 84%, 77%, and 83% (P = 0.035) for the subtypes within each group, respectively. Cox regression multivariate analysis showed that compared with the metformin group, all three subtypes of the, the non-metformin group showed poorer prognosis (hazard ratio [HR], 3.579; 95% confidence interval [CI], 1.506-8.506 [P = 0.004]; HR, 3.232; 95% CI, 1.839-5.678 [P < 0.001]; HR, 2.034; 95% CI,1.019-4.059 [P = 0.044] for Luminal A, Luminal B (high ki67), and Luminal B (her-2/neu+, respectively). Compared with the metformin group, the diabetic group showed poorer prognosis only for the Luminal B (high ki67) subtype (HR, 1.762; 95% CI, 1.033-3.005 [P = 0.038]). In addition, for the Luminal A, Luminal B (high ki67), and Luminal B (her-2/neu+) subgroups, there was a higher proportion of elderly patients (P < 0.001) and postmenopausal patients (P < 0.001) in the metformin and non-metformin groups than in the nondiabetic group. Moreover, the probability of having cardiovascular and cerebrovascular disease was also higher (P < 0.001) in the metformin and non-metformin groups. For the Luminal B (high ki67) and Luminal B (her-2/neu +) subgroups, there was a higher proportion of obese patients in the metformin and non-metformin groups (P < 0.001). In terms of clinical characteristics, for the Luminal B (high ki67) subtype, the proportion of patients with invasive ductal carcinoma was lower in the non-metformin group than in the other two groups (P = 0.001). In both the metformin and non-metformin groups, the proportion of T3/4 patients was higher (P < 0.001), the proportion of patients with lymph node metastasis was higher (P = 0.001), and the proportion of patients with vessel carcinoma embolus was higher (P = 0.001) compared with the nondiabetic group. In conclusion, compared with the metformin group, the non-metformin group had a poorer prognosis for all subtypes of luminal breast cancer. In the diabetic group, only patients with the Luminal B (high ki67) subtype exhibited a poorer prognosis. Therefore, different diabetes medication may have a different impact on the prognosis of different subtypes of luminal breast cancer.

Insulin receptor phosphorylation by endogenous insulin or the insulin analog AspB10 promotes mammary tumor growth independent of the IGF-I receptor

Endogenous hyperinsulinemia and insulin receptor (IR)/IGF-I receptor (IGF-IR) phosphorylation in tumors are associated with a worse prognosis in women with breast cancer. In vitro, insulin stimulation of the IR increases proliferation of breast cancer cells. However, in vivo studies demonstrating that IR activation increases tumor growth, independently of IGF-IR activation, are lacking. We hypothesized that endogenous hyperinsulinemia increases mammary tumor growth by directly activating the IR rather than the IGF-IR or hybrid receptors. We aimed to determine whether stimulating the IR with the insulin analog AspB10 could increase tumor growth independently of IGF-IR signaling. We induced orthotopic mammary tumors in control FVB/n and hyperinsulinemic MKR mice, and treated them with the insulin analog AspB10, recombinant human IGF-I, or vehicle. Tumors from mice with endogenous hyperinsulinemia were larger and had greater IR phosphorylation, but not IGF-IR phosphorylation, than those from control mice. Chronic AspB10 administration also increased tumor growth and IR (but not IGF-IR) phosphorylation in tumors. IGF-I led to activation of both the IGF-IR and IR and probably hybrid receptors. Our results demonstrate that IR phosphorylation increases tumor growth, independently of IGF-IR/hybrid receptor phosphorylation, and warrant consideration when developing therapeutics targeting the IGF-IR, but not the IR.

Targeting non-small cell lung cancer cells by dual inhibition of the insulin receptor and the insulin-like growth factor-1 receptor

Phase III trials of the anti-insulin-like growth factor-1 receptor (IGF1R) antibody figitumumab in non-small cell lung cancer (NSCLC) patients have been discontinued owing to lack of survival benefit. We investigated whether inhibition of the highly homologous insulin receptor (IR) in addition to the IGF1R would be more effective than inhibition of the IGF1R alone at preventing the proliferation of NSCLC cells. Signalling through IGF1R and IR in the NSCLC cell lines A549 and Hcc193 was stimulated by a combination of IGF1, IGF2 and insulin. It was inhibited by antibodies that block ligand binding, αIR3 (IGF1R) and IR47-9 (IR), and by the ATP-competitive small molecule tyrosine kinase inhibitors AZ12253801 and NVPAWD742 which inhibit both IGF1R and IR tyrosine kinases. The effect of inhibitors was determined by an anchorage-independent proliferation assay and by analysis of Akt phosphorylation. In Hcc193 cells the reduction in cell proliferation and Akt phosphorylation due to anti-IGF1R antibody was enhanced by antibody-mediated inhibition of the IR whereas in A549 cells, with a relatively low IR:IGF1R expression ratio, it was not. In each cell line proliferation and Akt phosphorylation were more effectively inhibited by AZ12253801 and NVPAWD742 than by combined αIR3 and IR47-9. When the IGF1R alone is inhibited, unencumbered signalling through the IR can contribute to continued NSCLC cell proliferation. We conclude that small molecule inhibitors targeting both the IR and IGF1R more effectively reduce NSCLC cell proliferation in a manner independent of the IR:IGF1R expression ratio, providing a therapeutic rationale for the treatment of this disease.

Weight control and cancer preventive mechanisms: role of insulin growth factor-1-mediated signaling pathways

Overweight and obese not only increase the risk of cardiovascular disease and type-2 diabetes mellitus, but are also now known risk factors for a variety of cancers. Weight control, via dietary calorie restriction and/or exercise, has been demonstrated to be beneficial for cancer prevention in various experimental models, but the underlying mechanisms are still not well defined. Recent studies conducted in a mouse skin carcinogenesis model show that weight loss induced a significant reduction of the circulating levels of insulin growth factor (IGF)-1 and other hormones, including insulin and leptin, resulting in reduced IGF-1-dependent signaling pathways, i.e. Ras-MAPK proliferation and protein kinase B-phosphoinositide 3-kinase (Akt-PI3K) antiapoptosis. Selective targeting IGF-1 to Akt/mammalian target of rapamycin and AMP-activated protein kinase pathways, via negative energy balance, might inactivate cell cycle progression and ultimately suppress tumor development. This review highlights the current studies focused on the major role of reducing IGF-1-activated signaling via weight control as a potential cancer preventive mechanism.

Hyperglycemia and prostate cancer recurrence in men treated for localized prostate cancer

BACKGROUND

Obesity is consistently linked with prostate cancer (PCa) recurrence and mortality, though the mechanism is unknown. Impaired glucose regulation, which is common among obese individuals, has been hypothesized as a potential mechanism for PCa tumor growth. In this study, we explore the relationship between serum glucose at time of treatment and risk of PCa recurrence following initial therapy.

METHODS

The study group comprised 1734 men treated with radical prostatectomy (RP) or radiation therapy (RT) for localized PCa between 2001-2010. Serum glucose levels closest to date of diagnosis were determined. PCa recurrence was determined based on PSA progression (nadir PSA+2 for RT; PSA≥0.2 for RP) or secondary therapy. Multivariate Cox regression was performed to determine whether glucose level was associated with biochemical recurrence after adjusting for age, race, body mass index, comorbidity, diagnosis of diabetes, Gleason Sum, PSA, treatment and treatment year.

RESULTS

Recurrence was identified in 16% of men over a mean follow-up period of 41 months (range 1-121 months). Those with elevated glucose (≥100 mg/dl) had a 50% increased risk of recurrence (HR 1.5, 95% CI: 1.1-2.0) compared with those with a normal glucose level (<100 mg/dl). This effect was seen in both those undergoing RP (HR 1.9, 95% CI: 1.0-3.6) and those treated with RT (HR 1.4, 95% CI: 1.0-2.0).

CONCLUSIONS

Glucose levels at the time of PCa diagnosis are an independent predictor of PCa recurrence for men undergoing treatment for localized disease.

The antidiabetic drug metformin inhibits uterine leiomyoma cell proliferation via an AMP-activated protein kinase signaling pathway

Uterine leiomyomas are the most common gynecological benign tumors and greatly affect reproductive health and wellbeing. Metformin is the most widely used antidiabetic drug in the world, and there is increasing evidence of a potential efficacy of this agent as an anticancer drug. In order to understand metformin's anti-tumorigenic potential better, in this study, we investigated the inhibitory effect of metformin and expression of key targets of metformin cell signaling in leiomyoma cells. Cell proliferation was assessed after exposure to metformin. Apoptosis was assessed by western blotting for cleaved-PARP and TUNEL staining. The expressions of phosphorylated AMPK and phosphorylated S6 were determined by western blotting. Metformin potently inhibited ELT-3 cell proliferation in a dose-dependent manner. Western blotting analysis demonstrated that metformin induced phosphorylation of AMPK and the inhibitory effect was attenuated with AMPK inhibitor, compound C. In parallel, treatment with metformin decreased phosphorylation of S6 protein. These experimental findings show that metformin is a potent inhibitor of cell proliferation in leiomyoma cells. This effect is mediated by AMPK activation and subsequent inhibition of the mTOR pathway. Thus, this study provides a possible mechanism of the action of metformin in the inhibition of leiomyoma cell growth.

Sphingosine kinase (SphK) 1 and SphK2 play equivalent roles in mediating insulin's mitogenic action

Insulin, an established mitogen that promotes breast cancer cell growth, has been implicated in the link between obesity and an increased risk of breast cancer. However, the current understanding of signaling pathways that mediate the mitogenic action of insulin remains incomplete. Here we provide the first evidence that insulin is capable of activating both sphingosine kinase (SphK) 1 and SphK 2, two isoenzymes that often exhibit opposing effects in the regulation of cell survival and growth. Insulin stimulates the phosphorylation of both SphK1 and SphK2 in a similar time- and dose-dependent manner. Interestingly, both isoenzymes are responsible equally for insulin-induced cell cycle progression and proliferation of MCF7 breast cancer cells, although SphK1 and SphK2 display different roles in mediating insulin-induced ERK1/2 and Akt activation. Moreover, the sphingosine 1-phosphate receptor 3, a key component of the SphK signaling system, is important for insulin-mediated mitogenic action in breast cancer cells. Furthermore, insulin receptor and type 1 IGF receptor (IGF1R) are responsible for the insulin-promoted mitogenic action on MCF7 breast cancer cells. Notably, IGF1R mediates insulin-stimulated phosphorylation of both SphK1 and SphK2, whereas insulin receptor is involved only in SphK1, but not SphK2, activation. Collectively the current study illustrates a new signaling system controlling the mitogenic action of insulin in breast cancer cells, suggesting a new strategy that pharmaceutically targets both isoenzymes of SphK for the management of breast cancer.

Insulin therapy and cancer in type 2 diabetes

Despite the availability of many other agents, insulin is widely used as a treatment for type 2 diabetes. In vitro, insulin stimulates the growth of cancer cells, through the interaction with insulin-like growth factor-1 (IGF-1) receptors and its own receptors. In observational surveys on type 2 diabetes, insulin therapy is associated with an increased incidence of several forms of cancer, although it is difficult to discriminate the effect of confounders from that of insulin itself. Randomized trials do not confirm the increased risk associated with insulin therapy, although they do not allow to rule out some negative effects on specific forms of cancer, at least at higher doses. Among insulin analogues, glargine has a higher affinity for the IGF-1 receptor and a greater mitogenic potency in vitro than human insulin, but it is extensively metabolized in vitro to products with low IGF-1 receptor affinity. Overall, epidemiological studies suggest a possible increase of risk with glargine, with respect to human insulin, only at high doses and for some forms of cancer (i.e., breast). Data from clinical trials do not confirm, but are still insufficient to totally exclude, such increased risk. However, beneficial effects of insulin outweigh potential cancer risks.

BMS-754807, a small-molecule inhibitor of insulin-like growth factor-1 receptor/insulin receptor, enhances gemcitabine response in pancreatic cancer

Gemcitabine has limited clinical benefits in pancreatic ductal adenocarcinoma (PDAC). Insulin-like growth factor (IGF) signaling proteins are frequently overexpressed in PDAC. The therapeutic potential of BMS-754807, a small-molecule inhibitor of IGF-type 1 receptor (IGF-1R) and insulin receptor (IR), and gemcitabine was evaluated in experimental PDAC. Cell proliferation and protein expression were measured by WST-1 assay and immunoblotting. Tumor growth and survival studies were conducted in murine xenografts. PDAC cells expressed phospho-IGF-1R protein. BMS-754807 and gemcitabine inhibited cell proliferation of PDAC cells; the combination of BMS-754807 with gemcitabine had additive effects. Addition of BMS-754807 decreased gemcitabine IC₅₀ from 9.7 μmol/L to 75 nmol/L for AsPC-1, from 3 μmol/L to 70 nmol/L for Panc-1, from 72 to 16 nmol/L for MIA PaCa-2, and from 28 to 16 nmol/L for BxPC-3 cells. BMS-754807 caused a decrease in phospho-IGF-1R and phospho-AKT proteins in AsPC-1 and Panc-1 cells. BMS-754807 and gemcitabine caused an increase in PARP-1 and caspase-3 cleavage. Net tumor growth inhibition in BMS-754807, gemcitabine, and BMS-754807+gemcitabine groups was 59%, 35%, and 94% as compared with controls. Effects of therapy on intratumoral proliferation and apoptosis corresponded with tumor growth inhibition data. BMS-754807 also caused a decrease in phospho-IGF-1R and phospho-AKT in tumor tissue lysates. Median animal survival (controls: 21 days) with BMS-754807 was 27 days (P = 0.03), with gemcitabine 28 days (P = 0.05), and in the BMS-754807+gemcitabine combination group, 41 days (P = 0.007). The strong antitumor activity of BMS-754807 in experimental PDAC supports the potential of BMS-754807-induced mechanisms for clinical PDAC therapy.

Diabetes and cancer II: role of diabetes medications and influence of shared risk factors

An association between type 2 diabetes mellitus (DM) and cancer has long been postulated, but the biological mechanism responsible for this association has not been defined. In part one of this review, we discussed the epidemiological evidence for increased risk of cancer, decreased cancer survival, and decreased rates of cancer screening in diabetic patients. Here we review the risk factors shared by cancer and DM and how DM medications play a role in altering cancer risk. Hyperinsulinemia stands out as a major factor contributing to the association between DM and cancer, and modulation of circulating insulin levels by DM medications appears to play an important role in altering cancer risk. Drugs that increase circulating insulin, including exogenous insulin, insulin analogs, and insulin secretagogues, are generally associated with an increased cancer risk. In contrast, drugs that regulate insulin signaling without increasing levels, especially metformin, appear to be associated with a decreased cancer risk. In addition to hyperinsulinemia, the effect of DM medications on other shared risk factors including hyperglycemia, obesity, and oxidative stress as well as demographic factors that may influence the use of certain DM drugs in different populations are described. Further elucidation of the mechanisms behind the association between DM, cancer, and the role of DM medications in modulating cancer risk may aid in the development of better prevention and treatment options for both DM and cancer. Additionally, incorporation of DM medication use into cancer prediction models may lead to the development of improved risk assessment tools for diabetic patients.

Insulin resistance and cancer risk: an overview of the pathogenetic mechanisms

Insulin resistance is common in individuals with obesity or type 2 diabetes (T2D), in which circulating insulin levels are frequently increased. Recent epidemiological and clinical evidence points to a link between insulin resistance and cancer. The mechanisms for this association are unknown, but hyperinsulinaemia (a hallmark of insulin resistance) and the increase in bioavailable insulin-like growth factor I (IGF-I) appear to have a role in tumor initiation and progression in insulin-resistant patients. Insulin and IGF-I inhibit the hepatic synthesis of sex-hormone binding globulin (SHBG), whereas both hormones stimulate the ovarian synthesis of sex steroids, whose effects, in breast epithelium and endometrium, can promote cellular proliferation and inhibit apoptosis. Furthermore, an increased risk of cancer among insulin-resistant patients can be due to overproduction of reactive oxygen species (ROS) that can damage DNA contributing to mutagenesis and carcinogenesis. On the other hand, it is possible that the abundance of inflammatory cells in adipose tissue of obese and diabetic patients may promote systemic inflammation which can result in a protumorigenic environment. Here, we summarize recent progress on insulin resistance and cancer, focusing on various implicated mechanisms that have been described recently, and discuss how these mechanisms may contribute to cancer initiation and progression.

The insulin and insulin-like growth factor receptor family in neoplasia: an update

Although several early phase clinical trials raised enthusiasm for the use of insulin-like growth factor I receptor (IGF1R)-specific antibodies for cancer treatment, initial Phase III results in unselected patients have been disappointing. Further clinical studies may benefit from the use of predictive biomarkers to identify probable responders, the use of rational combination therapies and the consideration of alternative targeting strategies, such as ligand-specific antibodies and receptor-specific tyrosine kinase inhibitors. Targeting insulin and IGF signalling also needs to be considered in the broader context of the pathophysiology that relates obesity and diabetes to neoplasia, and the effects of anti-diabetic drugs, including metformin, on cancer risk and prognosis. The insulin and IGFI receptor family is also relevant to the development of PI3K-AKT pathway inhibitors.