Acute Treatment With XMetA Activates Hepatic Insulin Receptors and Lowers Blood Glucose in Normal Mice.

It has been proposed that monoclonal antibodies may become therapeutics for metabolic diseases such as diabetes mellitus. We have previously characterized an allosteric monoclonal antibody to the human insulin receptor (IR), XMetA, that activated metabolic signaling leading to enhanced glucose transport in cultured cells, and chronically reduced fasting blood glucose levels in mouse models of diabetes mellitus. Under acute dosing conditions, the large size of an IR-binding antibody like XMetA (∼ 150 kDa) could lead to a more rapid access into liver, an insulin sensitive tissue with well-fenestrated capillaries, when compared to other insulin sensitive tissues with non-fenestrated capillaries, such as muscle and adipose. Thus, in the present study we administered XMetA (10 mg/kg) and insulin (0.5 U/kg) via IV injection, and for 90 min compared their effects on blood glucose lowering and IR activation in three of the major insulin-sensitive tissues of the normal fasted mouse: liver, adipose, and muscle. Like insulin, XMetA lowered blood glucose levels, although the effect was less rapid. Insulin activated IR autophosphorylation and Akt phosphorylation in liver, fat, and muscle. In contrast, IR activation by XMetA was primarily observed in the liver. Both insulin and XMetA lowered ß-hydroxybutyrate levels in plasma; however, only insulin reduced both non-esterified fatty acids (NEFA) and glycerol concentrations. These data indicate that, in normal mice, acute glucose regulation by XMetA is largely mediated by its action on the liver.

Differential pathway coupling of the activated insulin receptor drives signaling selectivity by XMetA, an allosteric partial agonist antibody.

The monoclonal antibody XMetA is an allosteric partial agonist of the insulin receptor (IR), which activates the metabolic Akt kinase signaling pathway while having little or no effect on the mitogenic extracellular signal-regulated kinase (ERK) signaling pathway. To investigate the nature of this selective signaling, we have conducted a detailed investigation of XMetA to evaluate specific phosphorylation and activation of IR, Akt, and ERK in Chinese hamster ovary cell lines expressing either the short or long isoform of the human IR. Insulin activated both pathways, but the phosphorylation of Akt was more sensitive to the hormone than the phosphorylation of ERK. Maximally effective concentrations of XMetA elicited phosphorylation patterns similar to 40-100 pM insulin, which were sufficient for robust Akt phosphorylation, but had little effect on ERK phosphorylation. These data indicate that the preferential signaling of XMetA is due to an innate difference in pathway sensitivity of Akt versus ERK responses to IR activation and partial agonism by XMetA, rather than a separate pathway-biased mechanism. The metabolic selectivity of partial IR agonists like XMetA, if recapitulated in vivo, may be a desirable feature of therapeutic agents designed to regulate blood glucose levels while minimizing undesirable outcomes of excessive IR mitogenic activation.

Detailed mechanistic analysis of gevokizumab, an allosteric anti-IL-1ß antibody with differential receptor-modulating properties.

Interleukin-1ß (IL-1ß) is a proinflammatory cytokine that is implicated in many autoinflammatory disorders, but is also important in defense against pathogens. Thus, there is a need to safely and effectively modulate IL-1ß activity to reduce pathology while maintaining function. Gevokizumab is a potent anti-IL-1ß antibody being developed as a treatment for diseases in which IL-1ß has been associated with pathogenesis. Previous data indicated that gevokizumab negatively modulates IL-1ß signaling through an allosteric mechanism. Because IL-1ß signaling is a complex, dynamic process involving multiple components, it is important to understand the kinetics of IL-1ß signaling and the impact of gevokizumab on this process. In the present study, we measured the impact of gevokizumab on the IL-1ß system using Schild analysis and surface plasmon resonance studies, both of which demonstrated that gevokizumab decreases the binding affinity of IL-1ß for the IL-1 receptor type I (IL-1RI) signaling receptor, but not the IL-1 counter-regulatory decoy receptor (IL-1 receptor type II). Gevokizumab inhibits both the binding of IL-1ß to IL-1RI and the subsequent recruitment of IL-1 accessory protein primarily by reducing the association rates of these interactions. Based on this information and recently published structural data, we propose that gevokizumab decreases the association rate for binding of IL-1ß to its receptor by altering the electrostatic surface potential of IL-1ß, thus reducing the contribution of electrostatic steering to the rapid association rate. These data indicate, therefore, that gevokizumab is a unique inhibitor of IL-1ß signaling that may offer an alternative to current therapies for IL-1ß-associated autoinflammatory diseases.

Insulin autoimmune syndrome (Hirata Disease) in European Caucasians taking α-lipoic acid.

OBJECTIVE: Lipoic acid (LA) is a widely used nutritional supplement and is sometimes used as an adjuvant treatment for diabetic neuropathy and other conditions. Insulin autoimmune syndrome (IAS, Hirata disease) is a rare cause of spontaneous hypoglycaemia, extremely high serum insulin levels and high titres of autoantibodies against endogenous insulin despite no prior exposure to exogenous insulin. In Japanese individuals, IAS is associated with the human leucocyte antigen (HLA) HLA-DRB1*04:06 allele and often occurs upon exposure to sulphhydryl-containing compounds including LA. Only one case has been reported in Caucasians. We now report six Caucasian patients taking LA with IAS and describe a unique HLA subtype in these patients. RESEARCH DESIGN AND METHODS: Six Caucasian patients (M = 3; F = 3), median age 63 years, presented with spontaneous episodes of fasting and postabsorptive hypoglycaemia associated with mainly neuroglycopenic symptoms. No patient was treated with insulin or had an insulinoma. Hypoglycaemic symptoms appeared 30 and 120 days after taking lipoic acid (LA; 600 mg/day). Case histories and standard laboratory analyses were utilized. RESULTS: Discontinuation of LA resulted in a reduction in hypoglycaemic episodes. All patients were treated with oral or iv glucose and prednisone (12.5-25 mg/day). HLA analysis revealed the HLA-DRB1*04:03 allele in five patients, while the HLA-DRB1*04:06 allele was present in one patient. CONCLUSIONS: This is the first report of LA-related IAS in Caucasians who possess the HLA-DRB1*04:03 allele, implicating this allele in the genetic susceptibility to IAS in Caucasians. The greater occurrence of the HLA-DRB1*04:03 allele in Caucasian and other populations, combined with the growing use of LA in developed countries, may be a future predictor of additional cases of IAS.

Variants of ENPP1 are associated with childhood and adult obesity and increase the risk of glucose intolerance and type 2 diabetes.

We identified a locus on chromosome 6q16.3-q24.2 (ref. 1) associated with childhood obesity that includes 2.4 Mb common to eight genome scans for type 2 diabetes (T2D) or obesity. Analysis of the gene ENPP1 (also called PC-1), a candidate for insulin resistance, in 6,147 subjects showed association between a three-allele risk haplotype (K121Q, IVS20delT-11 and A-->G+1044TGA; QdelTG) and childhood obesity (odds ratio (OR) = 1.69, P = 0.0006), morbid or moderate obesity in adults (OR = 1.50, P = 0.006 or OR = 1.37, P = 0.02, respectively) and T2D (OR = 1.56, P = 0.00002). The Genotype IBD Sharing Test suggested that this obesity-associated ENPP1 risk haplotype contributes to the observed chromosome 6q linkage with childhood obesity. The haplotype confers a higher risk of glucose intolerance and T2D to obese children and their parents and associates with increased serum levels of soluble ENPP1 protein in children. Expression of a long ENPP1 mRNA isoform, which includes the obesity-associated A-->G+1044TGA SNP, was specific for pancreatic islet beta cells, adipocytes and liver. These findings suggest that several variants of ENPP1 have a primary role in mediating insulin resistance and in the development of both obesity and T2D, suggesting that an underlying molecular mechanism is common to both conditions.

The role of membrane glycoprotein plasma cell antigen 1/ectonucleotide pyrophosphatase phosphodiesterase 1 in the pathogenesis of insulin resistance and related abnormalities.

Insulin resistance is a major feature of most patients with type 2 diabetes mellitus (T2D). A number of laboratories have observed that PC-1 (membrane [corrected] glycoprotein plasma cell antigen 1; also termed [corrected] ectonucleotide pyrophosphatase phosphodiesterase 1 or ENPP1) [corrected] is either overexpressed or overactive in muscle, adipose tissue, fibroblasts, and other tissues of insulin-resistant individuals, both nondiabetic and diabetic. Moreover, PC-1 (ENPP1) overexpression [corrected] in cultured cells in vitro and in transgenic mice in vivo, [corrected] impairs insulin stimulation of insulin receptor (IR) activation and downstream signaling. PC-1 binds to the connecting domain of the IR alpha-subunit that is located in residues 485-599. The connecting domain transmits insulin binding in the alpha-subunit to activation of tyrosine kinase activation in the beta-subunit. When PC-1 is overexpressed, it inhibits insulin [corrected]induced IR beta-subunit tyrosine kinase activity. In addition, a polymorphism of PC-1 (K121Q) in various ethnic populations is closely associated with insulin resistance, T2D, and cardio [corrected] and nephrovascular diseases. The product of this polymorphism has a 2- to 3-fold increased binding affinity for the IR and is more potent than the wild-type PC-1 protein (K121K) in inhibiting the IR. These data suggest therefore that PC-1 is a candidate protein that may play a role in human insulin resistance and T2D by its overexpression, its overactivity, or both.

Chromium supplementation in non-obese non-diabetic subjects is associated with a decline in insulin sensitivity.

BACKGROUND: The use of chromium supplements is widespread for the prevention and treatment of diabetes mellitus but there are conflicting reports on efficacy, possibly reflecting discrepant effects across different populations. In the present studies, we test the hypothesis that chromium supplementation raises serum chromium levels and correspondingly improves insulin sensitivity. METHODS: A double blind placebo-controlled randomized trial was conducted on 31 non-obese, normoglycemic subjects. After baseline studies, the subjects were randomized to placebo or chromium picolinate 500 µg twice a day. The primary endpoint was change in insulin sensitivity as measured by euglycemic hyperinsulinemic clamp. Pre-specified secondary endpoints included fasting lipids, blood pressure, weight, body composition measured by DXA scan. RESULTS: After 16 weeks of chromium picolinate therapy there was no significant change in insulin sensitivity between groups (p=0.83). There was, however, a strong association between serum chromium and change in insulin resistance (ß = -0.83, p=0.01), where subjects with the highest serum chromium had a worsening of insulin sensitivity. This effect could not be explained by changes in physiological parameters such as body weight, truncal fat and serum lipids with chromium therapy. CONCLUSIONS: Chromium therapy did not improve insulin sensitivity in non-obese normoglycemic individuals. Further, subjects who have high serum chromium levels paradoxically had a decline in insulin sensitivity. Caution therefore should be exercised in recommending the use of this supplement. TRIAL REGISTRATION: The study was registered on the NIH registry (clinicaltrials.gov) and the identifier is NCT00846248.

Functional variants of the HMGA1 gene and type 2 diabetes mellitus.

CONTEXT: High-mobility group A1 (HMGA1) protein is a key regulator of insulin receptor (INSR) gene expression. We previously identified a functional HMGA1 gene variant in 2 insulin-resistant patients with decreased INSR expression and type 2 diabetes mellitus (DM). OBJECTIVE: To examine the association of HMGA1 gene variants with type 2 DM. DESIGN, SETTINGS, AND PARTICIPANTS: Case-control study that analyzed the HMGA1 gene in patients with type 2 DM and controls from 3 populations of white European ancestry. Italian patients with type 2 DM (n = 3278) and 2 groups of controls (n = 3328) were attending the University of Catanzaro outpatient clinics and other health care sites in Calabria, Italy, during 2003-2009; US patients with type 2 DM (n = 970) were recruited in Northern California clinics between 1994 and 2005 and controls (n = 958) were senior athletes without DM collected in 2004 and 2009; and French patients with type 2 DM (n = 354) and healthy controls (n = 50) were enrolled at the University of Reims in 1992. Genomic DNA was either directly sequenced or analyzed for specific HMGA1 mutations. Messenger RNA and protein expression for HMGA1 and INSR were measured in both peripheral lymphomonocytes and cultured Epstein-Barr virus-transformed lymphoblasts from patients with type 2 DM and controls. MAIN OUTCOME MEASURES: The frequency of HMGA1 gene variants among cases and controls. Odds ratios (ORs) for type 2 DM were estimated by logistic regression analysis. RESULTS: The most frequent functional HMGA1 variant, IVS5-13insC, was present in 7% to 8% of patients with type 2 DM in all 3 populations. The prevalence of IVS5-13insC variant was higher among patients with type 2 DM than among controls in the Italian population (7.23% vs 0.43% in one control group; OR, 15.77 [95% confidence interval {CI}, 8.57-29.03]; P < .001 and 7.23% vs 3.32% in the other control group; OR, 2.03 [95% CI, 1.51-3.43]; P < .001). In the US population, the prevalence of IVS5-13insC variant was 7.7% among patients with type 2 DM vs 4.7% among controls (OR, 1.64 [95% CI, 1.05-2.57]; P = .03). In the French population, the prevalence of IVS5-13insC variant was 7.6% among patients with type 2 DM and 0% among controls (P = .046). In the Italian population, 3 other functional variants were observed. When all 4 variants were analyzed, HMGA1 defects were present in 9.8% of Italian patients with type 2 DM and 0.6% of controls. In addition to the IVS5 C-insertion, the c.310G>T (p.E104X) variant was found in 14 patients and no controls (Bonferroni-adjusted P = .01); the c.*82G>A variant (rs2780219) was found in 46 patients and 5 controls (Bonferroni-adjusted P < .001); the c.*369del variant was found in 24 patients and no controls (Bonferroni-adjusted P < .001). In circulating monocytes and Epstein-Barr virus-transformed lymphoblasts from patients with type 2 DM and the IVS5-13insC variant, the messenger RNA levels and protein content of both HMGA1 and the INSR were decreased by 40% to 50%, and these defects were corrected by transfection with HMGA1 complementary DNA. CONCLUSIONS: Compared with healthy controls, the presence of functional HMGA1 gene variants in individuals of white European ancestry was associated with type 2 DM.

Dyslipidemia and diabetes mellitus: Role of lipoprotein species and interrelated pathways of lipid metabolism in diabetes mellitus.

Diabetes mellitus is a complex disease. We are increasingly gaining a better understanding of its mechanisms at the molecular level. From these new insights, better therapeutic approaches should emerge. Diabetes mellitus is a syndrome with many associated subphenotypes. These include mitochondrial disorders, lipodystrophies, and inflammatory disorders involving cytokines. Levels of sphingosine-1-phosphate, which has recently been shown to play a role in glucose homeostasis, are low in diabetics, whereas levels of ceramides are increased. Major phenotypes associated with diabetes mellitus are dyslipidemias, notably hypertriglyceridemia and low high-density lipoprotein cholesterol levels. Both diabetes and dyslipidemia are strongly associated with increased risk for atherosclerotic vascular disease.

Obesity-related hypoxia via miR-128 decreases insulin-receptor expression in human and mouse adipose tissue promoting systemic insulin resistance.

BACKGROUND: Insulin resistance in visceral adipose tissue (VAT), skeletal muscle and liver is a prominent feature of most patients with obesity. How this association arises remains poorly understood. The objective of this study was to demonstrate that the decrease in insulin receptor (INSR) expression and insulin signaling in VAT from obese individuals is an early molecular manifestation that might play a crucial role in the cascade of events leading to systemic insulin resistance. METHODS: To clarify the role of INSR and insulin signaling in adipose tissue dysfunction in obesity, we first measured INSR expression in VAT samples from normal-weight subjects and patients with different degrees of obesity. We complemented these studies with experiments on high-fat diet (HFD)-induced obese mice, and in human and murine adipocyte cultures, in both normoxic and hypoxic conditions. FINDINGS: An inverse correlation was observed between increasing body mass index and decreasing INSR expression in VAT of obese humans. Our results indicate that VAT-specific downregulation of INSR is an early event in obesity-related adipose cell dysfunction, which increases systemic insulin resistance in both obese humans and mice. We also provide evidence that obesity-related hypoxia in VAT plays a determinant role in this scenario by decreasing INSR mRNA stability. This decreased stability is through the activation of a miRNA (miR-128) that downregulates INSR expression in adipocytes. INTERPRETATION: We present a novel pathogenic mechanism of reduced INSR expression and insulin signaling in adipocytes. Our data provide a new explanation linking obesity with systemic insulin resistance. FUNDING: This work was partly supported by a grant from Nutramed (PON 03PE000_78_1) and by the European Commission (FESR FSE 2014-2020 and Regione Calabria).

Nordihydroguaiaretic acid (NDGA), an inhibitor of the HER2 and IGF-1 receptor tyrosine kinases, blocks the growth of HER2-overexpressing human breast cancer cells.

We have reported that nordihydroguaiaretic acid (NDGA) inhibits the tyrosine kinase activities of the IGF-1 receptor (IGF-1R) and the HER2 receptor in breast cancer cells. Herein, we studied the effects of NDGA on the growth of estrogen receptor (ER) positive MCF-7 cells engineered to overexpress HER2 (MCF-7/HER2-18). These cells are an in vitro model of HER2-driven, ER positive, tamoxifen resistant breast cancer. NDGA was equally effective at inhibiting the growth of both parental MCF-7 and MCF-7/HER2-18 cells. Half maximal effects for both cell lines were in the 10-15 microM range. The growth inhibitory effects of NDGA were associated with an S phase arrest in the cell cycle and the induction of apoptosis. NDGA inhibited both IGF-1R and HER2 kinase activities in these breast cancer cells. In contrast, Gefitinib, an epidermal growth factor receptor inhibitor but not an IGF-1R inhibitor, was more effective in MCF-7/HER2-18 cells than in the parental MCF-7 cells and IGF binding protein-3 (IGFBP-3) was more effective against MCF-7 cells compared to MCF-7/HER2-18. MCF-7/HER2-18 cells are known to be resistant to the effects of the estrogen receptor inhibitor, tamoxifen. Interestingly, NDGA not only inhibited the growth of MCF-7/HER2-18 on its own, but it also demonstrated additive growth inhibitory effects when combined with tamoxifen. These studies suggest that NDGA may have therapeutic benefits in HER2-positive, tamoxifen resistant, breast cancers in humans.

Oxidative stress and stress-activated signaling pathways: a unifying hypothesis of type 2 diabetes.

In both type 1 and type 2 diabetes, the late diabetic complications in nerve, vascular endothelium, and kidney arise from chronic elevations of glucose and possibly other metabolites including free fatty acids (FFA). Recent evidence suggests that common stress-activated signaling pathways such as nuclear factor-kappaB, p38 MAPK, and NH2-terminal Jun kinases/stress-activated protein kinases underlie the development of these late diabetic complications. In addition, in type 2 diabetes, there is evidence that the activation of these same stress pathways by glucose and possibly FFA leads to both insulin resistance and impaired insulin secretion. Thus, we propose a unifying hypothesis whereby hyperglycemia and FFA-induced activation of the nuclear factor-kappaB, p38 MAPK, and NH2-terminal Jun kinases/stress-activated protein kinases stress pathways, along with the activation of the advanced glycosylation end-products/receptor for advanced glycosylation end-products, protein kinase C, and sorbitol stress pathways, plays a key role in causing late complications in type 1 and type 2 diabetes, along with insulin resistance and impaired insulin secretion in type 2 diabetes. Studies with antioxidants such as vitamin E, alpha-lipoic acid, and N-acetylcysteine suggest that new strategies may become available to treat these conditions.

A pilot dose-escalation study of the effects of nordihydroguareacetic acid on hormone and prostate specific antigen levels in patients with relapsed prostate cancer.

OBJECTIVE: To assess the tolerability of the effects of nordihydroguareacetic acid (NDGA) and its effect on prostate-specific antigen (PSA) kinetics in patients with relapsed prostate cancer, as among the many biological effects of NDGA is the inhibition of the insulin-like growth factor 1 receptor (IGF-1R) tyrosine kinase. PATIENTS AND METHODS: Eligible patients were those with an increasing PSA level after definitive local therapy, in either the non-castrate (androgen-dependent prostate cancer, ADPC) or the castrate state (castration-resistant prostate cancer, CRPC) with no evidence of metastatic disease by bone scan or computed tomography of the abdomen or pelvis. Treatment consisted of continuous oral daily dosing according to a planned dose escalation of 750, 1250, 1750, 2250 and 2500 mg of NDGA. PSA levels were measured every 28 days. Serial levels of testosterone, dihydrotestosterone, oestradiol and sex hormone-binding globulin were measured at baseline and monthly while on study therapy. RESULTS: Fifteen patients were enrolled, including 11 with ADPC and four with CRPC. There were asymptomatic increases in transaminase in six patients, two of which were grade 3, all occurring at >or=3 months. The increases in transaminase resolved after stopping NDGA but recurred with repeated dosing. Doses of NDGA up to 2500 mg/day caused no other toxicities. A median (range) of 5.5 (1-13) cycles were delivered. Of the 11 patients with ADPC, one had a decline in PSA level of >50% of the baseline value and one a decline of <50%. Three patients with ADPC had a greater than three-fold increase in PSA doubling time while on therapy, one from 11 to 46 months (750 mg), one from 9.5 to 49.5 months (1750 mg), and one from 5.9 to 46.2 months (2500 mg). There were no reductions in PSA level in patients with CRPC. There were no significant effects on levels of testosterone, dihydrotestosterone, oestradiol or sex hormone-binding globulin. CONCLUSIONS: Continuous daily dosing with NDGA is reasonably well tolerated but is associated with transaminitis in some patients, that occurs after several months on therapy. There were apparent effects on the rate of increase in PSA. Further study is required to determine the optimum pharmacokinetics and antitumour effects of this therapy.

Technical evaluation of in vivo abdominal fat and IMCL quantification using MRI and MRSI at 3 T.

OBJECTIVES: The objectives of this study were to develop protocols that measure abdominal fat and calf muscle lipids with magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), respectively, at 3 T and to examine the correlation between these parameters and insulin sensitivity. MATERIALS AND METHODS: Ten nondiabetic subjects [five insulin-sensitive (IS) subjects and five insulin-resistant (IR) subjects] were scanned at 3 T. Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were segmented semiautomatically from abdominal imaging. Intramyocellular lipids (IMCL) in calf muscles were quantified with single-voxel MRS in both soleus and tibialis anterior muscles and with magnetic resonance spectroscopic imaging (MRSI). RESULTS: The average coefficient of variation (CV) of VAT/(VAT+SAT) was 5.2%. The interoperator CV was 1.1% and 5.3% for SAT and VAT estimates, respectively. The CV of IMCL was 13.7% in soleus, 11.9% in tibialis anterior and 2.9% with MRSI. IMCL based on MRSI (3.8+/-1.2%) were significantly inversely correlated with glucose disposal rate, as measured by a hyperinsulinemic-euglycemic clamp. VAT volume correlated significantly with IMCL. IMCL based on MRSI for IR subjects was significantly greater than that for IS subjects (4.5+/-0.9% vs. 2.8+/-0.5%, P=.02). CONCLUSION: MRI and MRS techniques provide a robust noninvasive measurement of abdominal fat and muscle IMCL, which are correlated with insulin action in humans.

Role of gut microbiota and oxidative stress in the progression of non-alcoholic fatty liver disease to hepatocarcinoma: Current and innovative therapeutic approaches.

Non-alcoholic fatty liver disease (NAFLD) represents the most common chronic liver disease in industrialized countries. NAFLD progresses through the inflammatory phase of non-alcoholic steatohepatitis (NASH) to fibrosis and cirrhosis, with some cases developing liver failure or hepatocellular carcinoma (HCC). Liver biopsy remains the gold standard approach to a definitive diagnosis of NAFLD and the distinction between simple steatosis and NASH. The pathogenesis of NASH is still not clear. Several theories have been proposed ranging from the "Two Hit Theory" to the "Multiple Hit Theory". However, the general consensus is that the gut microbiota, oxidative stress, and mitochondrial damage play key roles in the pathogenesis of NASH. The interaction between the gut epithelia and some commensal bacteria induces the rapid generation of reactive oxygen species (ROS). The main goal of any therapy addressing NASH is to reverse or prevent progression to liver fibrosis/cirrhosis. This problem represents the first "Achilles' heel" of the new molecules being evaluated in most ongoing clinical trials. The second is the inability of these molecules to reach the mitochondria, the primary sites of energy production and ROS generation. Recently, a variety of non-pharmacological and pharmacological treatment approaches for NASH have been evaluated including vitamin E, the thiazolidinediones, and novel molecules related to NASH pathogenesis (including obeticholic acid and elafibranor). Recently, a new isoform of human manganese superoxide dismutase (MnSOD) was isolated and obtained in a synthetic recombinant form designated rMnSOD. This protein has been shown to be a powerful antioxidant capable of mediating ROS dismutation, penetrating biological barriers via its uncleaved leader peptide, and reducing portal hypertension and fibrosis in rats affected by liver cirrhosis. Based on these distinctive characteristics, it can be hypothesized that this novel recombinant protein (rMnSOD) potentially represents a new and highly efficient adjuvant therapy to counteract the progression from NASH to HCC.

A unique allosteric insulin receptor monoclonal antibody that prevents hypoglycemia in the SUR-1-/- mouse model of KATP hyperinsulinism.

Loss-of-function mutations of the ß-cell ATP-sensitive potassium channels (KATP) cause the most common and severe form of congenital hyperinsulinism (KATPHI), a disorder of ß-cell function characterized by severe hypoglycemia. Children with KATPHI are typically unresponsive to medical therapy and require pancreatectomy for intractable hypoglycemia. We tested the hypothesis that inhibition of insulin receptor signaling may prevent hypoglycemia in KATPHI. To test this hypothesis, we examined the effect of an antibody allosteric inhibitor of the insulin receptor, XMetD, on fasting plasma glucose in a mouse model of KATPHI (SUR-1-/- mice). SUR-1-/- and wild-type mice received twice weekly intraperitoneal injections of either XMetD or control antibody for 8 wks. Treatment with XMetD significantly decreased insulin sensitivity, and increased hepatic glucose output and fasting plasma glucose. These findings support the potential use of insulin receptor antagonists as a therapeutic approach to control the hypoglycemia in congenital hyperinsulinism.

Expression of insulin-like growth factor-1 receptor in local and metastatic prostate cancer.

PURPOSE: The insulin-like growth factor (IGF)-1 receptor is currently being targeted in clinical trials in prostate cancer. Despite this targeting, there are conflicting data on the presence of this receptor in human tumor samples, largely because of differences in technique. MATERIALS AND METHODS: Immunohistochemistry was used to determine the presence of IGF-1 receptor in frozen normal prostate and prostate cancer specimens. Clinical and pathologic parameters were correlated with IGF-1 receptor intensity and frequency of staining. Only 2-3+ staining on a scale of 0-3 was considered positive in this evaluation. RESULTS: IGF-1 receptor was expressed in normal prostate epithelium in 6 of 6 patients without cancer and in morphologically normal epithelium adjacent to tumor cells in 21 of 22 patients with cancer studied. IGF-1 receptor was present in the prostate tumor epithelium of 28 of 28 primary tumors, 3 of 5 locally recurrent androgen-independent tumors, and in 4 of 5 metastatic lymph nodes. Stromal staining patterns were positive in 2 of 28 specimens near benign epithelium compared to 19 of 30 specimens of stroma surrounding tumor epithelium (P < 0.0001, Fisher exact test). Stroma adjacent to Gleason grade >or=7 tumors showed higher intensity staining than that adjacent to lower grade tumors (P < 0.001). Expression of the closely related insulin receptor did not show expression in either normal or cancer epithelium, or in adjacent stroma. CONCLUSIONS: This study using frozen tissue shows widespread IGF-1 receptor expression in normal prostate, prostate cancers, and metastases. These data support investigations into IGF-1 receptor as a therapeutic target in prostate cancer.

IGF-binding protein-1 levels are related to insulin-mediated glucose disposal and are a potential serum marker of insulin resistance.

OBJECTIVE: IGF-binding protein (IGFBP)-1 is negatively regulated by insulin. We determined whether the measurement of IGFBP-1 in serum is a useful marker of insulin resistance. RESEARCH DESIGN AND METHODS: Twenty-three subjects underwent a euglycemic insulin clamp. Glucose disposal rates (M) were then correlated with measurements of IGFBP-1, fasting insulin levels, homeostasis model assessment (HOMA), and BMI. RESULTS: IGFBP-1 levels more strongly correlated with M (R = 0.73) than the other parameters such as BMI or HOMA. The level of this protein decreased in individuals who became more insulin sensitive by exercise training. CONCLUSIONS: These studies show a strong correlation between insulin sensitivity and the serum levels of IGFBP-1. These studies suggest, therefore, that measurement of this protein may be valuable in identifying those individuals with insulin resistance and those individuals who respond to interventional strategies.

Diarylureas are small-molecule inhibitors of insulin-like growth factor I receptor signaling and breast cancer cell growth.

In breast and certain other cancers, receptor tyrosine kinases, including the insulin-like growth factor I receptor (IGF-IR), play an important role in promoting the oncogenic process. The IGF-IR is therefore an important target for developing new anti-breast cancer therapies. An initial screening of a chemical library against the IGF-IR in breast cancer cells identified a diaryl urea compound as a potent inhibitor of IGF-IR signaling. This class of compounds has not been studied as inhibitors of the IGF-IR. We studied the effectiveness of one diaryl urea compound, PQ401, at antagonizing IGF-IR signaling and inhibiting breast cancer cell growth in culture and in vivo. PQ401 inhibited autophosphorylation of the IGF-IR in cultured human MCF-7 cells with an IC50 of 12 micromol/L and autophosphorylation of the isolated kinase domain of the IGF-IR with an IC50 <1 micromol/L. In addition, PQ401 inhibited the growth of cultured breast cancer cells in serum at 10 micromol/L. PQ401 was even more effective at inhibiting IGF-I-stimulated growth of MCF-7 cells (IC50, 6 micromol/L). Treatment of MCF-7 cells with PQ401 was associated with a decrease in IGF-I-mediated signaling through the Akt antiapoptotic pathway. Twenty-four hours of treatment with 15 micromol/L PQ401 induced caspase-mediated apoptosis. In vivo, treatment with PQ401 (i.p. injection thrice a week) reduced the growth rate of MCNeuA cells implanted into mice. These studies indicate that diaryl urea compounds are potential new agents to test in the treatment of breast and other IGF-I-sensitive cancers.

Cerebral Salt-Wasting Syndrome: Diagnosis by Urine Sodium Excretion.

BACKGROUND: Cerebral salt-wasting syndrome (CSWS) was initially described over 60 years ago in hyponatremic patients with a cerebral lesion. However, the diagnostic criteria for CSWS have not been fully established. Thus, when hyponatremia is observed in patients with CSWS, they may be misdiagnosed as having the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Thus, it is critical to differentiate between these 2 conditions because their treatments are diametrically opposed. MATERIALS AND METHODS: We carried out a retrospective study of 45 patients with CSWS and compared them to 60 normonatremic control patients, and 28 patients with SIADH. All patients had their 24-hour urine volumes and sodium (Na) excretion measured. RESULTS: In patients with CSWS, urinary Na excretion was 394 ± 369mmol/24 hours and urinary volume was 2,603 ± 996mL/24 hours; both values significantly greater than in controls (P < 0.01). By contrast, in patients with SIADH, the urine Na excretion was only 51 ± 25mmol/24 hours and urine volume was 745 ± 298mL/24 hours; values significantly lower than in patients with CSWS (P < 0.01). CONCLUSIONS: CSWS was diagnosed in patients with cerebral lesion who had (1) symptomatic hyponatremia, (2) urine Na excretion 2 standard deviations above controls and (3) increased urine volume. Patients with SIADH also had symptomatic hyponatremia but, in contrast to patients with CSWS, they had decreased Na excretion and urine volume. Thus urine Na excretion and volume are very important for diagnosing the cause of hyponatremia in patients with cerebral lesions.