Induction of insulin-like growth factor 2 expression in a mesenchymal cell line co-cultured with an ameloblast cell line

Various growth factors have been implicated in the regulation of cell proliferation and differentiation during tooth development. It has been unclear if insulin-like growth factors (IGFs) participate in the epithelium–mesenchyme interactions of tooth development. We previously produced three-dimensional sandwich co-culture systems (SW) containing a collagen membrane that induce the differentiation of epithelial cells. In the present study, we used the SW system to analyze the expression of IGFs and IGFRs. We demonstrate that IGF2 expression in mesenchymal cells was increased by SW. IGF1R transduces a signal; however, IGF2R does not transduce a signal. Recombinant IGF2 induces IGF1R and IGF2R expression in epithelial cells. IGF1R expression is increased by SW; however, IGF2R expression did not increase by SW. Thus, IGF2 signaling works effectively in SW. These results suggest that IGF signaling acts through the collagen membrane on the interaction between the epithelium and mesenchyme. In SW, other cytokines may be suppressed to induce IGF2R induction. Our results suggest that IGF2 may play a role in tooth differentiation

Low Circulating IGF-I Bioactivity in Elderly Men is associated with Increased Mortality

Context: Low IGF-I signaling activity prolongs lifespan in certain animal models, but the precise role of IGF-I in human survival remains controversial. The IGF-I kinase receptor activation assay (IGF-I KIRA) is a novel method for measuring IGF-I bioactivity in human serum. We speculated that determination of circulating IGF-I bioactivity is more informative than levels of immunoreactive IGFI. Objective: To study IGF-I bioactivity in relation to human survival. Design: Prospective observational study. Setting: A clinical research center at a university hospital. Study participants: 376 healthy elderly men (aged 73 to 94 years). Main outcome Measures: IGF-I bioactivity was determined by the IGF-I KIRA. Total and free IGF-I were determined by IGF-I immunoassays. Mortality was registered during follow-up (mean 82 months). Results: During the follow-up period of 8.6 years 170 men (45%) died. Survival of subjects in the highest quartile of IGF-I bioactivity was significantly better than in the lowest quartile, both in the total study group (HR = 1.8, (95% CI: 1.2 − 2.8, p = 0.01) as well as in subgroups having a medical history of cardiovascular disease (HR = 2.4 (95% CI: 1.3 − 4.3, p = 0.003) or a high inflammatory risk profile (HR = 2.3 (95% CI: 1.2 − 4.5, p = 0.01). Significant relationships were not observed for total or free IGF-I. Conclusion: Our study suggests that a relatively high circulating IGF-I bioactivity in elderly men is associated with extended survival and with reduced cardiovascular risk

Glargine and degludec: solution behaviour of higher dose synthetic insulins

Single, double and triple doses of the synthetic insulins glargine and degludec currently used in patient therapy are characterised using macromolecular hydrodynamic techniques (dynamic light scattering and analytical ultracentrifugation) in an attempt to provide the basis for improved personalised insulin profiling in patients with diabetes. Using dynamic light scattering and sedimentation velocity in the analytical ultracentrifuge glargine was shown to be primarily dimeric under solvent conditions used in current formulations whereas degludec behaved as a dihexamer with evidence of further association of the hexamers (“multi-hexamerisation”). Further analysis by sedimentation equilibrium showed that degludec exhibited reversible interaction between mono- and-di-hexamer forms. Unlike glargine, degludec showed strong thermodynamic non-ideality, but this was suppressed by the addition of salt. With such large injectable doses of synthetic insulins remaining in the physiological system for extended periods of time, in some case 24–40 hours, double and triple dose insulins may impact adversely on personalised insulin profiling in patients with diabetes

Growth hormone secretion is correlated with neuromuscular innervation rather than motor neuron number in early-symptomatic male amyotrophic lateral sclerosis mice

GH deficiency is thought to be involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). However, therapy with GH and/or IGF-I has not shown benefit. To gain a better understanding of the role of GH secretion in ALS pathogenesis, we assessed endogenous GH secretion in wild-type and hSOD1(G93A) mice throughout the course of ALS disease. Male wild-type and hSOD1(G93A) mice were studied at the presymptomatic, onset, and end stages of disease. To assess the pathological features of disease, we measured motor neuron number and neuromuscular innervation. We report that GH secretion profile varies at different stages of disease progression in hSOD1(G93A) mice; compared with age-matched controls, GH secretion is unchanged prior to the onset of disease symptoms, elevated at the onset of disease symptoms, and reduced at the end stage of disease. In hSOD1(G93A) mice at the onset of disease, GH secretion is positively correlated with the percentage of neuromuscular innervation but not with motor neuron number. Moreover, this occurs in parallel with an elevation in the expression of muscle IGF-I relative to controls. Our data imply that increased GH secretion at symptom onset may be an endogenous endocrine response to increase the local production of muscle IGF-I to stimulate reinnervation of muscle, but that in the latter stages of disease this response no longer occurs

Liver-Derived IGF-I Regulates Mean Life Span in Mice

Background: Transgenic mice with low levels of global insulin-like growth factor-I (IGF-I) throughout their life span, including pre- and postnatal development, have increased longevity. This study investigated whether specific deficiency of liver-derived, endocrine IGF-I is of importance for life span. Methods and Findings: Serum IGF-I was reduced by approximately 80 % in mice with adult, liver-specific IGF-I inactivation (LI-IGF-I-/- mice), and body weight decreased due to reduced body fat. The mean life span of LI-IGF-I-/- mice (n = 84) increased 10 % vs. control mice (n = 137) (Cox’s test, p,0.01), mainly due to increased life span (16%) of female mice [LI-IGF-I-/- mice (n = 31): 26.761.1 vs. control (n = 67): 23.060.7 months, p,0.001]. Male LI-IGF-I-/- mice showed only a tendency for increased longevity (p = 0.10). Energy expenditure, measured as oxygen consumption during and after submaximal exercise, was increased in the LI-IGF-I-/- mice. Moreover, microarray and RT-PCR analyses showed consistent regulation of three genes (heat shock protein 1A and 1B and connective tissue growth factor) in several body organs in the LI-IGF-I-/- mice. Conclusions: Adult inactivation of liver-derived, endocrine IGF-I resulted in moderately increased mean life span. Body weight and body fat decreased in LI-IGF-I-/- mice, possibly due to increased energy expenditure during exercise. Genes earlier reported to modulate stress response and collagen aging showed consistent regulation, providing mechanisms tha

Luteolin decreases IGF-II production and downregulates insulin-like growth factor-I receptor signaling in HT-29 human colon cancer cells

<p>Abstract</p> <p>Background</p> <p>Luteolin is a 3',4',5,7-tetrahydroxyflavone found in various fruits and vegetables. We have shown previously that luteolin reduces HT-29 cell growth by inducing apoptosis and cell cycle arrest. The objective of this study was to examine whether luteolin downregulates the insulin-like growth factor-I receptor (IGF-IR) signaling pathway in HT-29 cells.</p> <p>Methods</p> <p>In order to assess the effects of luteolin and/or IGF-I on the IGF-IR signaling pathway, cells were cultured with or without 60 μmol/L luteolin and/or 10 nmol/L IGF-I. Cell proliferation, DNA synthesis, and IGF-IR mRNA levels were evaluated by a cell viability assay, [³H]thymidine incorporation assays, and real-time polymerase chain reaction, respectively. Western blot analyses, immunoprecipitation, and <it>in vitro </it>kinase assays were conducted to evaluate the secretion of IGF-II, the protein expression and activation of IGF-IR, and the association of the p85 subunit of phophatidylinositol-3 kinase (PI3K) with IGF-IR, the phosphorylation of Akt and extracellular signal-regulated kinase (ERK)1/2, and cell division cycle 25c (CDC25c), and PI3K activity.</p> <p>Results</p> <p>Luteolin (0 - 60 μmol/L) dose-dependently reduced the IGF-II secretion of HT-29 cells. IGF-I stimulated HT-29 cell growth but did not abrogate luteolin-induced growth inhibition. Luteolin reduced the levels of the IGF-IR precursor protein and IGF-IR transcripts. Luteolin reduced the IGF-I-induced tyrosine phosphorylation of IGF-IR and the association of p85 with IGF-IR. Additionally, luteolin inhibited the activity of PI3K activity as well as the phosphorylation of Akt, ERK1/2, and CDC25c in the presence and absence of IGF-I stimulation.</p> <p>Conclusions</p> <p>The present results demonstrate that luteolin downregulates the activation of the PI3K/Akt and ERK1/2 pathways via a reduction in IGF-IR signaling in HT-29 cells; this may be one of the mechanisms responsible for the observed luteolin-induced apoptosis and cell cycle arrest.</p

Growth hormone axis in chronic kidney disease

Chronic kidney disease (CKD) in children is associated with dramatic changes in the growth hormone (GH) and insulin-like growth factor (IGF-1) axis, resulting in growth retardation. Moderate-to-severe growth retardation in CKD is associated with increased morbidity and mortality. Renal failure is a state of GH resistance and not GH deficiency. Some mechanisms of GH resistance are: reduced density of GH receptors in target organs, impaired GH-activated post-receptor Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling, and reduced levels of free IGF-1 due to increased inhibitory IGF-binding proteins (IGFBPs). Treatment with recombinant human growth hormone (rhGH) has been proven to be safe and efficacious in children with CKD. Even though rhGH has been shown to improve catch-up growth and to allow the child to achieve normal adult height, the final adult height is still significantly below the genetic target. Growth retardation may persist after renal transplantation due to multiple factors, such as steroid use, decreased renal function and an abnormal GH–IGF1 axis. Those below age 6 years are the ones to benefit most from transplantation in demonstrating acceleration in linear growth. Newer treatment modalities targeting the GH resistance with recombinant human IGF-1 (rhIGF-1), recombinant human IGFBP3 (rhIGFBP3) and IGFBP displacers are under investigation and may prove to be more effective in treating growth failure in CKD

Growth Hormone Improves Growth Retardation Induced by Rapamycin without Blocking Its Antiproliferative and Antiangiogenic Effects on Rat Growth Plate

Rapamycin, an immunosuppressant agent used in renal transplantation with antitumoral properties, has been reported to impair longitudinal growth in young individuals. As growth hormone (GH) can be used to treat growth retardation in transplanted children, we aimed this study to find out the effect of GH therapy in a model of young rat with growth retardation induced by rapamycin administration. Three groups of 4-week-old rats treated with vehicle (C), daily injections of rapamycin alone (RAPA) or in combination with GH (RGH) at pharmacological doses for 1 week were compared. GH treatment caused a 20% increase in both growth velocity and body length in RGH animals when compared with RAPA group. GH treatment did not increase circulating levels of insulin-like growth factor I, a systemic mediator of GH actions. Instead, GH promoted the maturation and hypertrophy of growth plate chondrocytes, an effect likely related to AKT and ERK1/2 mediated inactivation of GSK3β, increase of glycogen deposits and stabilization of β-catenin. Interestingly, GH did not interfere with the antiproliferative and antiangiogenic activities of rapamycin in the growth plate and did not cause changes in chondrocyte autophagy markers. In summary, these findings indicate that GH administration improves longitudinal growth in rapamycin-treated rats by specifically acting on the process of growth plate chondrocyte hypertrophy but not by counteracting the effects of rapamycin on proliferation and angiogenesis

IGF-I induced genes in stromal fibroblasts predict the clinical outcome of breast and lung cancer patients

<p>Abstract</p> <p>Background</p> <p>Insulin-like growth factor-1 (IGF-I) signalling is important for cancer initiation and progression. Given the emerging evidence for the role of the stroma in these processes, we aimed to characterize the effects of IGF-I on cancer cells and stromal cells separately.</p> <p>Methods</p> <p>We used an <it>ex vivo </it>culture model and measured gene expression changes after IGF-I stimulation with cDNA microarrays. <it>In vitro </it>data were correlated with <it>in vivo </it>findings by comparing the results with published expression datasets on human cancer biopsies.</p> <p>Results</p> <p>Upon stimulation with IGF-I, breast cancer cells and stromal fibroblasts show some common and other distinct response patterns. Among the up-regulated genes in the stromal fibroblasts we observed a significant enrichment in proliferation associated genes. The expression of the IGF-I induced genes was coherent and it provided a basis for the segregation of the patients into two groups. Patients with tumours with highly expressed IGF-I induced genes had a significantly lower survival rate than patients whose tumours showed lower levels of IGF-I induced gene expression (<it>P </it>= 0.029 - Norway/Stanford and <it>P </it>= 7.96e-09 - NKI dataset). Furthermore, based on an IGF-I induced gene expression signature derived from primary lung fibroblasts, a separation of prognostically different lung cancers was possible (<it>P </it>= 0.007 - Bhattacharjee and <it>P </it>= 0.008 - Garber dataset).</p> <p>Conclusion</p> <p>Expression patterns of genes induced by IGF-I in primary breast and lung fibroblasts accurately predict outcomes in breast and lung cancer patients. Furthermore, these IGF-I induced gene signatures derived from stromal fibroblasts might be promising predictors for the response to IGF-I targeted therapies.</p> <p>See the related commentary by Werner and Bruchim: <url>http://www.biomedcentral.com/1741-7015/8/2</url></p