Higher IGF-I Levels Research Articles

Abstract ED04-02: The role of genes in protecting against age-related disease in cancer

Abstract ED04-02 Despite evidence for a substantial genetic component, the inherited biological factors that promote extended life span (longevity) in humans remain unknown. We have comprehensively characterized over 450 Ashkenazi Jewish families with exceptional longevity (survival in good health to at least age 95) and have identified several biological markers that may be causative in their longevity. These subjects and their offspring have 2-3 fold increases in rates of polymorphism in 3 genes all validated by other in other studies. Two genes are regulating lipoprotein--cholesterol ester transfer protein (CETP) and apolipoprotein C-3 (APOC-3)--and decrease in plasma levels CETP and APOC-3. Another gene is Adiponectin (ADIPOQ) regulating insulin action and inflammation. We have also demonstrated that these genotypes and phenotypes are associated with less hypertension (HTN), cardiovascular disease (CVD) and metabolic syndrome (MS), and improved cognitive function. However, these genes have not been shown yet to protect against cancer. Modulation of GH/IGF-1 axis is conferring longevity in mamalians and low IGF-1 levels is associated with decreased rates of cancers in humans. We demonstrated a gender-specific increase in serum IGFI associated with a smaller stature in female offspring of centenarians. Sequence analysis of the IGF1 and IGF1 receptor (IGF1R) genes of female centenarians showed overrepresentation of heterozygous mutations in the IGF1R gene among centenarians relative to controls that are associated with high serum IGFI levels and reduced activity of the IGFIR as measured in transformed lymphocytes. Thus, genetic alterations in the human IGF1R that result in altered IGF signaling pathway confer an increase in susceptibility to human longevity, suggesting a role of this pathway in modulation of human lifespan, possibly by protecting against cancer. Citation Information: Cancer Prev Res 2008;1(7 Suppl):ED04-02.

Abstract A93: Ethnic and anthropometric correlates of IGF axis in the United States

Abstract A93 Insulin-like growth factor-1 (IGF-1) levels are positively related to some cancers and negatively related to cardiovascular disease. These conditions are also related to insulin resistance and high body weight leading to the hypothesis that IGF-1 levels may, in part, mediate the association of high body weight with these health outcomes. Using the National Health and Nutrition Examination Survey (NHANES) III population, we examined the associations between IGF-1, IGFBP-3, and the IGF-1/IGFBP-3 molar ratio with anthropometric measures in a large, United States population-based study where these associations could also be stratified by race/ethnicity and gender. The study population consisted of 3168 women and 2635 men who participated in NHANES III and provided a fasting morning serum sample. The study population was 44% non-Hispanic white, 28.2% non-Hispanic black, and 27.7% Mexican-American. On average, the female participants in the study were approximately 45 years old with a body mass index (BMI) of 26.3 while the male participants were approximately 43 years old with a BMI of 26.9. Linear regression models were used to determine the associations of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 molar ratio with anthropometric variables across race/ethnicity and gender. The anthropometric measures included height, weight, waist-to-hip ratio, waist circumference, sum of skinfolds, and percent body fat and were obtained by trained personnel in the NHANES mobile examination center. IGF-1 and IGFBP-3 were measured by staff at Diagnostic System Laboratories (DSL, Inc., Webster, TX). BMI, waist-to-hip ratio, and waist circumference were inversely associated with IGF-1 levels across all race/ethnicity and gender subgroups except for non-Hispanic black men. The magnitude of the regression coefficients differed across racial/ethnic groups. In contrast, very few anthropometric measures where significantly associated with IGFBP-3 levels. The exception to this is non-Hispanic black men, where all anthropometric measures except height were positively associated with IGFBP-3 levels. The IGF-1/IGFBP-3 molar ratio was inversely associated with all anthropometric measures, except height, in all subgroups of the population. In addition, when examining mean levels of biomarkers across tertile of BMI, Mexican-American men and women had the lowest levels of IGF-1 and non-Hispanic white men and women had the highest levels of IGFBP-3. For the IGF-1/IGFBP-3 molar ratio, non-Hispanic black men and women had the highest ratios across all tertiles of BMI. The racial and ethnic differences in the levels of IGF-1, IGFBP-3, and the IGF-1/IGFBP-3 molar ratio and longitudinal evaluation of their associations with anthropometrics measures merit further investigation since IGF-1 levels have been hypothesized to be a contributor to many health outcomes. Our data are not consistent with the hypothesis that the association of high IGF-1 levels with health outcomes such as increased cancer risk is mediated through high BMI. Citation Information: Cancer Prev Res 2008;1(7 Suppl):A93.

Early programming of the IGF-I axis: Negative association between IGF-I in infancy and late adolescence in a 17-year longitudinal follow-up study of healthy subjects

Background: IGF-I is a major regulator of growth, influenced primarily by diet in infancy and primarily by GH in childhood. Breastfed infants have lower IGF-I levels compared to formula fed and tend to be shorter. The higher protein content of infant formula has a stimulatory effect on IGF-I production. Conversely, studies suggest that later in childhood, those breastfed are taller and have higher IGF-I levels. Therefore, it has been suggested that the IGF-I axis may be programmed by diet during infancy. The association between IGF-I in infancy and later life is not known. Objective: To examine the association between IGF-I in infancy and adolescence. Design: Infants (109) from the observational Copenhagen cohort study. Methods: Serum-IGF-I was measured during infancy (2, 6, and 9 months) and at follow-up at 17 years. Associations were examined by correlation tests and linear regression controlling for gender, breastfeeding, and other covariates. Likelihood ratio test based on residual log likelihood was applied for analysis including all measurements during infancy. Results: There was an inverse association between IGF-I at 9 months and 17 years ( r = −0.39, P = 0.014, and n = 40). A 1 ng/ml higher IGF-I concentration at 9 months corresponded to 0.95 ng/ml lower IGF-I concentration at 17 years. IGF-I levels at 2 and 6 months were not significantly associated with IGF-I at 17 years, but the estimated directions were negative. These associations were not changed when adjusted for breastfeeding and other covariates except IGF-I at 2 months which was significantly negatively associated with IGF-I at 17 years ( P = 0.030) corresponding to a 0.96 ng/ml lower IGF-I concentration at 17 years per ng/ml IGF-I at 2 months. Inclusion of all measurements during infancy showed a negative association with 17-year values ( r = −0.26, P = 0.043, and n = 109). Conclusion: The results support the hypothesis that the IGF-I axis can be programmed early in life.

Lack of Socs2 expression reduces lifespan in high-growth mice

The high-growth (HG) phenotype in mice is characterized by a 30-50% postweaning overgrowth with a substantial increase in plasma insulin-like growth factor I (IGF1) levels, which is directly related to a deletion (hg) on chromosome 10 that includes the suppressor of cytokine signaling 2 (Socs2) gene. Reduced plasma IGF1 levels have been associated with extended lifespan in mice, although the aging-related effects of abnormally high IGF1 levels without elevated growth hormone levels have never been assessed in mammals. Within this context, the hg deletion was introgressed into C57BL/6J (B6) and FVB backgrounds, and a survival analysis was performed on the longevity records of 200 B6 (91 wild-type and 109 homozygous hg mutants) and 69 FVB (32 wild-type and 37 hg mutants) mice. Longevity was examined using a piecewise Weibull proportional hazards model solved through a Bayesian perspective and Markov chain Monte Carlo sampling. Lifespan was significantly reduced in both strains in homozygous hg mice, with a death risk between 3.689 (B6) and 4.347 (FVB) times higher than in wild-type mice (non-overlapped highest posterior density regions at 95%). These results highlight the effects of the Socs2 gene on aging regulation, likely related with variations described in plasma IGF1 levels. This result is consistent with previous research in dwarf mutant mice and other species, and characterizes the HG mutant mice as a unique and interesting animal model for accelerated aging research.

Serum Concentrations of Insulin-Like Growth Factor and Insulin-Like Growth Factor Binding Protein 3 and Recurrent Colorectal Adenomas

Insulin-like growth factor I (IGF-I) and its primary binding protein, IGFBP-3, have been associated with colorectal cancer incidence in prior epidemiologic studies. High concentrations of IGF-I generally result in increasing risk and high concentrations of IGFBP-3 in decreasing risk. Only one prior study of IGF-I and IGFBP-3 and adenoma recurrence has been reported. We assayed fasting serum from 375 subjects with and 375 subjects without a recurrent adenoma during the course of the Polyp Prevention Trial to determine baseline concentrations of IGF-I and IGFBP-3. To estimate relative risk of adenoma recurrence over the course of 4 years of follow-up for each of these serum measures, we calculated odds ratios (OR) and 95% confidence intervals (CI) using multivariable logistic regression models adjusting for age, gender, body mass index, intervention group, aspirin, smoking, ethnicity, and education. For both IGF-I and IGFBP-3, we found trends indicating decreased risk for subjects in the high compared with the low quartile (for IGF-I: OR, 0.65; 95% CI 0.41-1.01; for IGFBP-3: OR, 0.66; 95% CI, 0.42-1.05). The associations were even greater for advanced adenomas (for IGF-I: OR, 0.51; 95% CI, 0.21-1.29; for IGFBP-3: OR, 0.32; 95% CI, 0.13-0.82). These results showed an unexpected null association, or even the suggestion of a reduction in risk for recurrent adenoma, with not just high IGFBP-3 concentration but also with high levels of IGF-I. Why IGF-I would decrease risk of recurrent adenoma (as distinct from incident adenoma or colorectal cancer) is not clear.

High IGF-I levels imply active acromegaly even when GH levels are 'normal'

High IGF-I levels imply active acromegaly even when GH levels are 'normal'

Expression of insulin-like growth factors (IGFs) and IGF signaling: molecular complexity in uterine leiomyomas

To study whether dysregulation of insulin-like growth factors (IGFs) and IGF signaling are common molecular changes in symptomatic leiomyomas (fibroids) and whether IGFs are associated with large fibroids. Examination of IGFs and IGF pathway genes in a large cohort of fibroids at transcriptional and translational levels. Mechanisms leading to alterations of IGFs and related genes were also analyzed. University clinical research laboratory. Hysterectomies for symptomatic fibroids were collected: 180 cases from paraffin-embedded tissues and 50 cases from fresh-frozen tissues. Tissue microarray and immunohistochemistry, DNA methylation analysis, reverse-transcriptase polymerase chain reaction, and Western blot. Transcription and translation analyses of IGF-1/2, p-AKT, p-S6K, and TSC1/2 in fibroids and matched myometrium. Insulin-like growth factors and downstream effectors were dysregulated in approximately one third of fibroids. All except for IGF-2 seemed to be abnormally regulated at translation levels. Up-regulation of IGF-2 messenger RNAs was contributed by all four alternating slicing promoters. There was a positive correlation of IGF-1 and p-AKT over-expression with fibroid size. Insulin-like growth factor 1 but not IGF-2 levels directly correlated with activation of p-AKT and p-S6K. Altered expressions of IGFs and their related downstream proteins were found in one third of fibroids. Large fibroids show high levels of IGF-1 and p-AKT activity compared with small ones.

Neonatal stem cells exhibit specific characteristics in function, proliferation, and cellular signaling that distinguish them from their adult counterparts

Stem cells may be a novel treatment modality for organ ischemia, possibly through beneficial paracrine mechanisms. Stem cells from older hosts have been shown to exhibit decreased function during stress. We therefore hypothesized that 1) neonatal bone marrow mesenchymal stem cells (nBMSCs) would produce different levels of IL-6, VEGF, and IGF-1 compared with adults (aBMSCs) when stimulated with TNF or LPS; 2) differences in cytokines would be due to distinct cellular characteristics, such as proliferation or pluripotent potential; and 3) differences in cytokines would be associated with differences in p38 MAPK and ERK signaling within nBMSCs. BMSCs were isolated from adult and neonatal mice. Cells were exposed to TNF or LPS with or without p38 or ERK inhibition. Growth factors were measured via ELISA, proliferation via daily cell counts, cell surface markers via flow cytometry, and pluripotent potential via alkaline phosphatase activity. nBMSCs produced lower levels of IL-6 and VEGF, but higher levels of IGF-1 under basal conditions, as well as after stimulation with TNF, but not LPS. Neonatal and adult BMSCs had similar pluripotent potentials and cell surface markers, but nBMSCs proliferated faster. Furthermore, p38 and ERK appeared to play a more substantial role in nBMSC cytokine and growth factor production. Neonatal stem cells may aid in decreasing the local inflammatory response during ischemia, and could possibly be expanded more rapidly than adult cells prior to therapeutic use.

Relationship between umbilical cord blood insulin-like growth factors and anthropometry in term newborns.

Birth size is associated with long-term morbidity. Insulin-like growth factor (IGF) system is the most important endocrine factor influencing fetal growth. During rapid somatic growth, free-to-total IGF-I ratio is increased, resulting in higher IGF-I bioavailability. The purpose of this study was to investigate the association of free-to-total IGF-I ratios, IGF-II, and IGF-binding protein (IGFBP)-3 umbilical cord levels with anthropometric data of term neonates. Umbilical venous plasma samples were obtained from 95 term neonates and analyzed by enzyme-linked immunosorbent assay. The large-for-gestational age (LGA) neonates had higher free IGF-I, total IGF-I, and IGFBP-3 levels than small-for-gestational age (SGA) neonates (P < 0.01, 0.001, 0.01, respectively) and higher total IGF-I and IGFBP-3 levels than appropriate-for-gestational age (AGA) neonates (P < 0.05, 0.01, respectively). The free-to-total IGF-I ratios and IGF-II levels were not different among SGA, AGA, and LGA neonates. Free IGF-I, total IGF-I, and IGFBP-3 levels were positively correlated with birth weight (r = 0.34, P < 0.001; r = 0.41, P < 0.001; r = 0.25, P < 0.05, respectively). Multiple linear regression analyses revealed that only total IGF-I levels was the independent predictive variable for birth weight. Our data suggest total IGF-I is the most important factor in the IGF system for determining fetal growth, at least near term gestation. Free-to-total IGF-I ratios may mostly be determined by total IGF-I. If birth size is associated with adult chronic metabolic diseases, total IGF-I may be involved in the pathogenesis.

A growth hormone-secreting adenoma with incomplete nerve bundle formation

We present a unique case of an adenoma secreting growth hormone (GH), showing incomplete nerve bundle formation without ganglion cells. A 47-year-old man presenting with acromegaly was revealed to have high serum GH and IGF-1 levels. The concentrations of the other adenohypophysial hormones were within the normal range. Histology revealed an unusual pituitary adenoma containing many nerve bundle-like structures. Adenoma cells with ovoid or round hyperchromatic nuclei and eosinophilic cytoplasms lacked the typical features of ganglion cells. The nerve bundles consisted of slender elongated cells. These fibers were arranged into groups in a roughly parallel fashion. By immunohistochemistry, many adenoma cells were positive for GH, prolactin, thyrotropin beta, synaptophysin and chromogranin. Fibrous bodies revealed by keratin immunostaining were found only in adenoma cells. Scattered star-shaped adenoma cells showed the same immunoreactivity as folliculo-satellite cells. Adenoma cells, but not the bundle-like structures, were also positive for Pit-1. Immunostaining for neurofilament protein, GFAP, vimentin, and S-100 protein revealed variable amounts of fibrils within the bundle-like structures. Scattered immunoreactivity for myelin basic protein and synaptophysin was also found in the bundle area. Our case is the first GH-secreting pituitary adenoma showing incomplete nerve bundle differentiation and lacking mature ganglion cells.

The relationship between adiponectin, leptin, insulin, insulin-like growth factor and IGF binding protein-3 in cord blood and neonatal anthropometric parameters

Purpose : This study was designed to examine the effects of adiponectin, leptin, insulin, insulin-like growth factor (IGF)-I and IGF binding protein (BP)-3 levels in cord blood on weight, length, and adiposity at birth in healthy term infants. In addition, we evaluated the mechanism to change the hormone levels in appropriate for gestational age (AGA) during the first month. Methods : We collected cord blood from 200 term neonates (109 males, 91 females) with no perinatal problems, and measured the hormone levels and anthropometric parameters including weight, length, and skin-fold thickness. Term neonates were divided into 3 groups as follows: birth weight appropriate for gestational age (AGA) (n=132), birth weight less for gestational age (SGA) (n=29), and birth weight more for gestational age (LGA) (n=39). Venous blood samples of 15 fullterm healthy neonates were obtained at 3, 7, and 30 d after birth. Results : The adiponectin, insulin, and IGF-I levels were significantly lower in the SGA group than in the AGA and LGA groups. The leptin levels were significantly higher in the LGA group than in the AGA and SGA groups. Cord blood adiponectin, leptin, insulin, IGF-I, and IGFBP-3 levels correlated significantly and positively with birth weight and the sum of the skin-fold thickness. A significant positive correlation was observed between adiponectin, leptin, and IGF-I levels and birth weight. Adiponectin level correlated significantly with that leptin level (r=0.191, P=0.038), but not with insulin, IGF-I and IGFBP-3 levels. IGF-I levels were higher in females than in males. At 7 d after birth, the leptin level decreased along with physiologic weight loss, and then increased. IGF-I, also decreased at 3 d, significantly increased 1 month later. Conclusion : We suggest that adiponectin, leptin, insulin, IGF-I, and IGFBP-3 play an important role in regulating fetal growth. Adiponectin may be involved in regulating fetal growth through mechanisms different from those mediated by insulin or IGF-I. High levels of IGF-I in female neonates indicates a gender difference which serves as evidence for in utero sexual dimorphism. It is likely that IGF-I has a more important role than that of hormones in postnatal growth.

Serum levels of IGF-1 in elderly women engaged in various motor activities

Study aim: To compare serum levels of IGF-1 in elderly women engaged in diverse activities. Material and methods: Four groups of subjects, aged 63 – 78 years were studied: untrained (Control; n = 10), practicing dance (Dance; n = 30), practicing meditation (Meditation; n = 28) and engaged in weight training (Training; n = 30). Their engagement in those activities lasted at least 6 months. IGF-1 was determined by chemiluminescence. Results: Training group had significantly (p<0.05) higher levels of IGF-1 than Meditation or Control groups, Dance group having significantly (p<0.05) higher levels than the Control group. Conclusions: Intense motor activities seem to bring about an increase in IGF-1 concentrations in elderly women.

Serum levels of free insulin-like growth factor-I and clinical value in healthy children

Purpose : The serum levels of total insulin-like growth factor (IGF)-I and IGF binding protein (IGFBP)- 3 reflect endogenous growth hormone (GH) secretion in healthy children. Free form of IGF-I which is suggested to have more potent biological action than complex form of IGF-I. The aim of this study is to investigate the serum levels of free IGF-I and its clinical value in healthy children. Methods : Serum levels of total IGF-I and IGFBP-3 were determined in 494 healthy children (248 boys and 246 girls) by RIA and IRMA. Serum level of free IGF-I was determined in 206 healthy children (103 boys and 103 girls) by IRMA. Results : The free IGF-I level increased with age in both sex. The free IGF-I level increased continuously between 7 and 15 years of age in boys, but decrement was noted after 14 years of age in girls. Serum total IGF-I level also increased with age in similar pattern of that of free IGF-I. There were no significant differences of mean values of the ratio of free IGF-I/total IGF-I in relation to age in both sex. And there were significant correlations between the level of free IGF-I and total IGF-I and the ratio of total IGF-I/IGFBP-3, respectively. Conclusion : In healthy children, serum free IGF-I increased with age in both sex and high free IGF-I level may play an important role in pubertal growth spurt. Our results suggest that the increased serum free IGF-I level in puberty may reflect changes in total IGF-I rather than IGFBP-3. But free IGF-I does not have more clinical value than total IGF-I because of no significant differences of mean values of the ratio of free IGF-I/total IGF-I in relation to age.

Ergebnisse einer unizentrischen endokrinologischen Nachsorge onkologischer Patienten im Kindes- und Adoleszentenalter

Established reports about endocrine follow-ups in children and adolescents with cancer were rare. 53 children were included in the clinical trial. The mean age was 9.6 years (0.5; 17.2 years), 10 patients died within the study period. The mean body length was normal with -0.14 SDS (-2.3; 2.5 SDS), as well as the body weight with 0.01 SDS and BMI with a mean of -0.03 SDS. Children and adolescents with different types of malignant tumors were included. According to the therapy protocol or tumor entity we divided this population in 5 subgroups (group 1 leukemia with 17 patients, group 2 lymphoma with 11 patients, group 3 tumor of CNS with 10 patients, group 4 bone and soft tissue tumors with 8 patients, group 5 different tumors with 7 patients). Anthropometrical and laboratory parameters were analyzed in intervals of 6 months over 2 years from the time point of diagnosis. We found differences in body height in children affected by cerebral tumors at the time of diagnosis and therefore before any therapy was started. These patients were significantly shorter (-0.6 SDS) than the other children. The body weight increased within the first year of therapy and was still higher than normal in the second year (comparison at the time point; from start to the first year+0.5 SDS, to second year+0.4 SDS) independently from the cortisone administration. Moreover, significant differences in the growth factor concentrations between the groups and time points were identified. Interestingly, children who survived their malignant disease tended to have higher levels of IGF-I and IGFBP-3 concentration than the patients who died within the study period. Additionally, the thyroid function was affected, shown as an increase of TSH with a concomitant decrease of the free thyroxin in 91% of all patients independent from the diagnosis (start TSH 1.8, fT4 15.6, after first year TSH 2.8, fT4 15.0). Thyroid function was monitored in 12 children, in 5 patients a short- or long-term substitution with thyroid hormone was indicated. Endocrine testing was initiated in 4 children, in 2 patients affection of the adrenal gland could be excluded, a suspected pituitary dysfunction after radiation was confirmed in 2 patients. We could represent that children and adolescents with malignant diseases showed affection of the endocrine system due to the tumour and the intensive therapy. The dysregulations in the endocrine system can be diagnosed through closely spaced monitoring and interdisciplinary cooperation.

Polycystic ovaries and the polycystic ovary syndrome phenotype in women with active acromegaly

Previous retrospective studies have suggested that women with acromegaly may present with menstrual irregularity and symptoms/signs of hyperandogenism, a phenotype similar to that of the polycystic ovary syndrome (PCOS). The aim of this study was to investigate prospectively the presence of the PCOS phenotype (PCOSP) and polycystic ovaries (PCO) on ultrasonography in women with active acromegaly. Women within the reproductive age range (21-43 years) with active acromegaly of recent onset and/or previous surgical and/or medical therapy were studied. Subjects underwent a physical examination; fasting bloods for androgens, pituitary hormones and metabolic parameters; an oral glucose tolerance test (OGTT) to estimate disease activity and insulin resistance; and a transvaginal ultrasound. Six women had newly diagnosed acromegaly, and eight still had active disease following previous surgical and/or medical treatment. Seven women were found to have PCO and six fulfilled the criteria for PCOSP; six of these women, five with PCOSP, had a pituitary macroadenoma. Women with PCOSP had significantly increased mean ovarian volumes and characteristic ovarian morphology compared to women without PCOSP (P < 0.05), higher levels of IGF-1 and testosterone and lower SHBG levels that did not reach statistical significance. A positive correlation between IGF-1 and mean ovarian volume was identified only in women with PCOSP (r = 0.851, P < 0.05). PCO and PCOSP are relatively common in women with acromegaly and may account for some of the symptoms related to gonadal dysfunction irrespective of the size of the pituitary tumour. It is likely that IGF-1 alone or in combination with GH and/or insulin resistance may be involved.

IGF‐I and mammographic density in four geographic locations: A pooled analysis

Insulin-like growth factor (IGF-I) and prolactin have been found to be associated with breast cancer risk and with mammographic density. In a pooled analysis from 4 geographic locations, we investigated the association of percent mammographic density with serum levels of IGF-I, IGFBP-3 and prolactin. The pooled data set included 1,327 pre- and postmenopausal women: Caucasians from Norway, Arizona and Hawaii, Japanese from Hawaii and Japan, Latina from Arizona, and Native Hawaiians from Hawaii. Serum samples were assayed for IGF-I, IGFBP-3 and prolactin levels using ELISA assays. Mammographic density was quantified using a computer-assisted density method. After stratification by menopausal status, multiple regression models estimated the relation between serum analytes and breast density. All serum analytes except prolactin among postmenopausal women differed significantly by location/ethnicity group. Among premenopausal subjects, IGF-I levels and the molar ratio were highest in Hawaii, intermediate in Japan and lowest in Arizona. For IGFBP-3, the order was reversed. Among postmenopausal subjects, Norwegian women had the highest IGF-I levels and women in Arizona had the lowest while women in Japan and Hawaii had intermediate levels. We observed no significant relation between percent density and IGF-I or prolactin levels among pre-and postmenopausal women. The significant differences in IGF-I levels by location but not ethnicity suggest that environmental factors influence IGF-I levels, whereas percent breast density varies more according to ethnic background than by location. Based on this analysis, the influence of circulating levels of IGF-I, IGFBP-3, and prolactin on percent density appears to be very small.

Association between Serum Insulin-Like Growth Factor-I Levels and Thyroid Disorders in a Population-Based Study

There is current debate on whether serum IGF-I levels are associated with thyroid disorders. The aims of the present study were: 1) to investigate possible associations between serum IGF-I levels and thyroid disorders and 2) to analyze the role of serum IGF binding protein (IGFBP)-3 and TSH levels for these associations. This was a cross-sectional Study of Health in Pomerania. The study was conducted in the general population of northeast Germany. The study population comprised 3662 subjects (1746 women) without history of thyroid disorders. No interventions have been performed. Goiter and thyroid nodules were determined by ultrasound. Serum TSH levels less than 0.25 mIU/liter were considered decreased. Adjusted for major confounders and risk factors for thyroid disorders, subjects with serum IGF-I levels above the upper tertile had higher odds for goiter relative to subjects with serum IGF-I levels below the lower tertile [odds ratio (OR) 1.67; 95% confidence interval (CI) 1.24-2.26 in women; OR 2.04; 95% CI 1.55-2.68 in men]. A similar association was present for thyroid nodules in men (OR 1.64; 95% CI 1.17-2.32) and for decreased serum TSH levels in women (OR 1.65; 95% CI 1.00-2.69). Serum IGFBP-3 levels were not associated with thyroid disorders and did not represent effect modifiers for the association between serum IGF-I levels and the endpoints. We conclude that high serum IGF-I levels are associated with goiter. Whereas high serum IGF-I levels are also related to thyroid nodules in men, they are related to decreased serum TSH levels in women. Serum IGFBP-3 and TSH levels did not modulate these associations.

Temperature and salinity effects on plasma insulin-like growth factor-I concentrations and growth in juvenile turbot ( Scophthalmus maximus)

The effects of temperature and salinity on plasma IGF-I levels and its interrelationship with growth, daily feed intake and feed conversion of juvenile turbot (initial mean weight 14 g) were investigated by rearing fish at 10, 14, 18 and 22 °C and 15, 25 and 33.5‰ for 3 months. The plasma IGF-I levels increased with increasing temperatures reaching a plateau around 18 °C. Further, both temperature and salinity had a significant effect on growth, daily feed intake and feed conversion efficiency in juvenile turbot. Growth, food consumption, and food conversion efficiency were highest at 18 °C and 15‰, and lowest at 10 °C and 33.5‰. Although there was a high variation between IGF-I values within all groups there was a positive relationship between IGF-I levels and specific growth rates and daily feed intake. The levels of IGF-I were almost three times higher for fish with higher growth rates than for those with lower growth. In addition, the results show evidence for an increased appetite in fish with high plasma IGF-I levels. Interestingly, there was no correlation between environmental salinity and IGF-I levels, although decreased salinity improves growth and feed conversion efficiency.

IGF-II regulates metastatic properties of choriocarcinoma cells through the activation of the insulin receptor

Choriocarcinoma is a highly malignant tumor that can arise from trophoblasts of any type of gestational event but most often from complete hydatidiform mole. IGF-II plays a fundamental role in placental development and may play a role in gestational trophoblastic diseases. Several studies have shown that IGF-II is expressed at high levels in hydatidiform moles and choriocarcinoma tissues; however, conflicting data exist on how IGF-II regulates the behaviour of choriocarcinoma cells. The purpose of this study was to determine the contribution of the receptors for IGF-I and insulin to the actions of IGF-II on the regulation of choriocarcinoma cells metastasis. An Immuno Radio Metric Assay was used to analyse the circulating and tissue levels of IGF-I and IGF-II in 24 cases of hydatidiform mole, two cases of choriocarcinoma and eight cases of spontaneous abortion at the same gestational age. The JEG-3 choriocarcinoma cell line was used to investigate the role of IGF-II in the regulation of cell invasion. We found that mole and choriocarcinoma tissue express high levels of IGF-II compared to first trimester placenta. Both IGF-I and IGF-II regulate choriocarcinoma cell invasion in a dose dependent manner but through a different mechanism. IGF-II effects involve the activation of the InsR while IGF-I uses the IGF-IR. The positive effects of IGF-II on invasion are the result of enhanced cell adhesion and chemotaxis (specifically towards collagen IV). The actions of IGF-II but not those of IGF-I were sensitive to inhibition by the insulin receptor inhibitor HNMPA(AM)3. Our results demonstrate that the insulin receptor regulates choriocarcinoma cell invasion.

Discordância entre IGF-1 e GH pós-sobrecarga de glicose no rastreamento de acromegalia em paciente com macroprolactinoma: relato de caso e revisão sobre o tema

We describe a patient with macroprolactinoma and discrepant insulin-like growth factor (IGF-1) concentration (elevated) and growth hormone (GH) values during a 75 g oral glucose tolerance test (normal), that were measured to evaluate the co-secretion of GH by tumor. With the bromocriptin use, the patient achieved normalization of prolactin, but persisted with high levels of IGF1, suggesting to be subclinical acromegaly. After the development of new more sensitive GH assays, cases of discrepant GH and IGF-1 results have been observed and taken to some authors to suggest that GH nadir concentration during 75 g OGTT used to acromegaly diagnosis and treatment could be lower than values considered currently normal. Thus, if this is confirmed, subclinical and oligosymptomatic acromegaly cases could have earlier diagnoses.