Free insulin‐like growth factors (IGF‐I and IGF‐II) in human serum

Frystyk, Jan; Skjærbæk, Christian; Dinesen, Bo; Ørskov, Hans

doi:10.1016/0014-5793(94)00602-4

Cited by 292 publications

(211 citation statements)

References 22 publications

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“…In this study it was not possible to directly compare IGF-II concentrations in lean and obese subjects, but nevertheless the present obese cohort showed markedly higher levels of free and total IGF-II than previously observed in lean subjects with a similar age, thereby confirming earlier findings (17,20,27). We now show that a diet-induced weight loss is accompanied by a reduction in free as well as total IGF-II levels, which thereby approach values in normal-weight subjects.…”

Section: Discussionsupporting

confidence: 88%

“…Weight loss, on the other hand, is known to normalize the secretion of GH, and in some obese cohorts it also increases serum total IGF-I (31). In the present study the diet-induced weight loss caused a significant increase in serum total IGF-I, IGFBP-1-bound IGF-I, IGFBP-1 and IGFBP-2, while free IGF-I remained constant and above the levels previously reported in lean subjects (17,20,34). Normally, overnight fasting levels of free IGF-I are correlated positively with total IGF-I and inversely with IGFBP-1 and -2 (34).…”

Section: Discussionsupporting

confidence: 52%

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Pro- and mature IGF-II during diet-induced weight loss in obese subjects

Espelund¹,

Bruun²,

Richelsen³

et al. 2005

eur j endocrinol

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Background: In normal subjects up to 10% of circulating insulin-like growth factor II (IGF-II) consists of pro-IGF-II. However, its regulation and biological impact remains unknown. In obese subjects, serum free and total IGF-II are increased, and we therefore investigated the impact of obesity and diet on serum pro-IGF-II. Design: Non-diabetic, obese subjects (n ¼ 34) with a body mass index (BMI) of 38.9^0.5 kg/m 2 were subjected to 8 weeks with very low calorie diet (800 kcal/day) followed by 12 weeks with a weightstabilizing diet. Fasting serum was collected before the study, and after 8 and 20 weeks. Pro-IGF-II was determined after acid-gel chromatography using a novel, highly specific in-house assay, free and total IGFs were measured after ultrafiltration and acid-ethanol extraction, respectively, and IGF-binding proteins (IGFBPs) were measured with specific immunoassays. Results: Diet reduced BMI and fasting levels of insulin and glucose (P , 0.001). Serum pro-IGF-II was markedly reduced in obese subjects as compared with matched normal-weight controls (means and 95% confidence intervals: 93 mg/l (82 -104 mg/l) versus 171 mg/l (152 -192 mg/l), respectively; P , 0.001), and levels remained unchanged after the weight loss. In contrast, during the study period total and free IGF-II decreased (P , 0.05), whereas total IGF-I, IGFBP-1 and IGFBP-2 increased (P , 0.001). Serum free IGF-I remained unaltered. Cross-sectional and longitudinal correlation analyses showed that pro-IGF-II was closer and more consistently associated with IGF-I than IGF-II. Conclusion: This study demonstrates that pro-IGF-II is reduced in obesity, in contrast to mature IGF-II. This indicates a hitherto unrecognized link between nutrition and pro-IGF-II. In addition, our data indicate that pro-IGF-II is regulated independently of mature IGF-II.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionsupporting

confidence: 52%

Pro- and mature IGF-II during diet-induced weight loss in obese subjects

Espelund¹,

Bruun²,

Richelsen³

et al. 2005

eur j endocrinol

Self Cite

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“…The use of total IGF measurements may be troublesome because of the complex in vivo interaction between the IGFs and their IGFBPs. Total IGF levels are influenced by the binding capacity in serum, which may impede total IGF measurements in reflecting IGF activity, whereas free IGFs determined by ultrafiltration is a measure of unbound IGF available for interaction with IGF and insulin receptors (24). Our data document the pitfall of using total IGF measurements alone.…”

Section: Discussionmentioning

confidence: 81%

Elevated free IGF2 levels in localized, early-stage breast cancer in women

Espelund

Cold²,

Frystyk³

et al. 2008

European Journal of Endocrinology

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Objective: Epidemiological studies imply an association between circulating IGF1 and breast cancer, whereas the role of IGF2, which also acts on the IGF1 receptor, is less settled. This study investigates the association between IGF2 and breast cancer in patients with localized disease. Design: The participants were women with well-characterized, early stage, localized breast cancer (nZ43) and matched healthy women (nZ38), from whom fasting serum levels of IGF-related peptides were measured. Results: In patients, mean free IGF2 was increased (C57%, P!0.001), in spite of reduced total IGF2 levels (K12%, PZ0.003) when compared with controls. Similar changes were seen in free IGF1 (C28%, PZ0.004) and total IGF1 (K16% PZNS). Pro-IGF2 and IGF-binding protein 1 (IGFBP1) were unchanged. IGFBP2 was reduced by 22% in the patients (PZ0.004). The patients showed reduced IGFBP3 protease activity and accordingly increased levels of intact IGFBP3, whereas total IGFBP3 was unchanged. Conclusion: Women with localized, early-stage breast cancer show elevated circulating free IGF1 and IGF2, reduced total IGF2 and alterations in IGFBPs. The changes observed despite minimal cancer disease suggest a role for the circulating IGF system in the progression of breast cancer in women.European Journal of Endocrinology 159 595-601

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“…-10 −9 mol/l [28,29], whereas only IGF significantly stimulated glucose metabolism and DNA synthesis at a low concentration in HCASMCs.…”

Section: Discussionmentioning

confidence: 99%

Expression and function of receptors for insulin-like growth factor-I and insulin in human coronary artery smooth muscle cells

Chisalita

Arnqvist

2005

Diabetologia

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Aims/hypothesis: Hyperinsulinaemia and insulin resistance, as well as low IGF-I, have been implicated in the pathogenesis of cardiovascular disease. Little is known about direct effects of IGF-I and insulin on human coronary artery smooth muscle cells (HCASMCs). Our aim was to characterise the expression and function of IGF-I receptor (IGF-IR) and insulin receptor (IR) in HCASMCs. Materials and methods: Cultured HCASMCs were used. mRNA expression was measured by quantitative real-time RT-PCR analysis. Receptor proteins, phosphorylation of β-subunits and the presence of hybrid IR/IGF-IR were analysed by immunoprecipitation and western blotting. DNA synthesis and glucose metabolism were assessed using [

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Free insulin‐like growth factors (IGF‐I and IGF‐II) in human serum

Cited by 292 publications

References 22 publications

Pro- and mature IGF-II during diet-induced weight loss in obese subjects

Pro- and mature IGF-II during diet-induced weight loss in obese subjects

Elevated free IGF2 levels in localized, early-stage breast cancer in women

Expression and function of receptors for insulin-like growth factor-I and insulin in human coronary artery smooth muscle cells

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