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Growth hormone (GH) has been used for over 35 years, and its safety and efficacy has been studied extensively. Experimental studies showing the permissive role of GH/insulin-like growth factor 1 (IGF-I) in carcinogenesis have raised concerns regarding the safety of GH replacement in children and adults who have received treatment for cancer and those with intracranial and pituitary tumours. A consensus statement was produced to guide decision-making on GH replacement in children and adult survivors of cancer, in those treated for intracranial and pituitary tumours and in patients with increased cancer risk. With the support of the European Society of Endocrinology, the Growth Hormone Research Society convened a Workshop, where 55 international key opinion leaders representing 10 professional societies were invited to participate. This consensus statement utilized: (1) a critical review paper produced before the Workshop, (2) five plenary talks, (3) evidence-based comments from four breakout groups, and (4) discussions during report-back sessions. Current evidence reviewed from the proceedings from the Workshop does not support an association between GH replacement and primary tumour or cancer recurrence. The effect of GH replacement on secondary neoplasia risk is minor compared to host- and tumour treatment-related factors. There is no evidence for an association between GH replacement and increased mortality from cancer amongst GH-deficient childhood cancer survivors. Patients with pituitary tumour or craniopharyngioma remnants receiving GH replacement do not need to be treated or monitored differently than those not receiving GH. GH replacement might be considered in GH-deficient adult cancer survivors in remission after careful individual risk/benefit analysis. In children with cancer predisposition syndromes, GH treatment is generally contraindicated but may be considered cautiously in select patients.

Context: Insulin-like growth factor (IGF)1 gene mutations are extremely rare causes of pre- and postnatal growth retardation. Phenotype can be heterogenous with varying degrees of neurosensory deafness, cognitive defects, glucose metabolism impairment and short stature. Objective: This study describes a 12.6-year-old girl presenting with severe short stature and insulin resistance, but with normal hearing and neurological development at the lower limit of normal. Methods: DNA was obtained from the proband and both parents for whole exome sequencing (WES). In silico analysis was performed to predict the impact of the IGF1 variant on IGF1 and insulin receptors (IGF1R and IR) signaling. Phosphorylation of the IGF1R at activating Tyr residues and cell proliferation analyses were used to assess the ability of each subject's IGF1 to bind and activate IGF1R. Results: The proband had low immunoreactive IGF1 in serum and WES revealed a novel homozygous IGF1 missense variant (c.247A>T), causing a change of serine 83 for cysteine (p.Ser83Cys; p.Ser35Cys in mature peptide). The proband's parents were heterozygous for this mutation. In silico analyses indicated the pathogenic potential of the variant with electrostatic variations with the potential of hampering the interaction with the IGF1R but strengthening the binding to IR. The mutant IGF1 protein had a significantly reduced activity on in vitro bioassays. Conclusion: We describe a novel IGF1 mutation leading to severe loss of circulating IGF1 immunoreactivity and bioactivity. In silico modeling predicts that the mutant IGF1 could interfere with IR signaling, providing a possible explanation for the severe insulin resistance observed in the patient. The absence of significant hearing and neurodevelopmental involvement in the present case is unusual and broadens the clinical spectrum of IGF1 mutations. [ABSTRACT FROM AUTHOR]

Most rodent models of insulin resistance are accompanied by decreased circulating adiponectin levels. Adiponectin treatment improves the metabolic phenotype by increasing fatty acid oxidation in skeletal muscle and suppressing hepatic glucose production. Muscle IGF-I receptor (IGF-IR)-lysine-arginine (MKR) mice expressing dominant-negative mutant IGF-IRs in skeletal muscle are diabetic with insulin resistance in muscle, liver, and adipose tissue. Adiponectin levels are elevated in MKR mice, suggesting an unusual discordance between insulin resistance and adiponectin responsiveness. Therefore, we investigated the metabolic actions of adiponectin in MKR mice. MKR and ob/ob mice were treated both acutely (28 [micro]g/g) and chronically (for 2 wk) with full-length adiponectin. Acute hypoglycemic effects of adiponectin were evident only in ob/ob mice but not in MKR mice. Chronic adiponectin treatment significantly improved both insulin sensitivity and glucose tolerance in ob/ob but not in MKR mice. Adiponectin receptor mRNA levels and adiponectin-stimulated phosphorylation of AMPK in skeletal muscle and liver were similar among MKR, wild-type, and ob/ob mice. Thus MKR mice are adiponectin resistant despite normal expression of adiponectin receptors and normal AMPK phosphorylation in muscle and liver. MKR mice may be a useful model for dissecting relationships between insulin resistance and adiponectin action in regulation of glucose homeostasis. adiponectin resistance; muscle insulin-like growth factor-I receptor-lysine-arginine mouse doi:10.1152/ajpendo.00319.2005

The antiobesity and antidiabetic effects of the [[beta].sub.3]-adrenergic agonists were investigated on nonobese type 2 diabetic MKR mice after injection with a [[beta].sub.3]-adrenergic agonist, CL-316243. An intact response to acute CL-316243 treatment was observed in MKR mice. Chronic intraperitoneal CL-316243 treatment of MKR mice reduced blood glucose and serum insulin levels. Hyperinsulinemic euglycemic clamps exhibited improvement of the whole body insulin sensitivity and glucose homeostasis concurrently with enhanced insulin action in liver and adipose tissue. Treating MKR mice with CL-316243 significantly lowered serum and hepatic lipid levels, in part due to increased whole body triglyceride clearance and fatty acid oxidation in adipocytes. A significant reduction in total body fat content and epididymal fat weight was observed along with enhanced metabolic rate in both wild-type and MKR mice after treatment. These data demonstrate that [[beta].sub.3]-adrenergic activation improves the diabetic state of nonobese diabetic MKR mice by potentiation of free fatty acid oxidation by adipose tissue, suggesting a potential therapeutic role for [[beta].sub.3]-adrenergic agonists in nonobese diabetic subjects. insulin-like growth factor 1 receptor mutation: type 2 diabetes

A delayed onset of puberty, slow pubertal progress and minimal slowing of linear growth in a 17-year old boy is reported. A study revealed that the proclatin and cortisol levels and thyroid function were normal in this patient.

Context Pheochromocytomas and paragangliomas (pheo/pgl) are neuroendocrine tumours derived from chromaffin cells. Although mostly benign, up to 26% of pheo/pgl will undergo malignant transformation. Reliable histological signs to differentiate benign pheo/pgl from malignant tumours are currently lacking. Increased IGF-1 R expression has been shown during progression to metastatic phenotypes of several types of cancer. Objective To analyse the distribution and expression of the IGF-1 R in pheo/pgl of different genetic origin and degree of malignancy. Measurements We studied the expression of the IGF-1R protein by immunohistochemistry, in 40 primary tumours from patients with pheo/pgl from different genetic aetiology (11 of 29 metastatic/nonmetastatic diseases). Results We found a strong association between increased expression of IGF-1 R and malignant behaviour regardless of the age at diagnosis and the genetic aetiology. IGF-1 R labelling was mostly weak in primary tumours from patients with nonmetastatic pheo/pgl. Conversely, intense IGF-1 R labelling was predominant in cases of pheo/pgl with confirmed metastatic disease. The risk of metastases was 11·7 times higher if tumour IGF-1 R labelling was intense independently of age at diagnosis. The probability of remaining free of metastases was higher in patients with pheo/pgl scored weak for IGF-1 R at 60 months and more than twofold higher at 120 months of follow-up than in patients with intense IGF-1 R labelling in their primary tumours. Conclusions Our results strongly suggest that IGF-1 R is associated with malignancy in familial pheo/pgl and that IGF-1 R expression in the primary tumour might be a useful tool to detect those patients harbouring pheo/pgl who have an increased risk of metastasis. [ABSTRACT FROM AUTHOR]

Most rodent models of insulin resistance are accompanied by decreased circulating adiponectin levels. Adiponectin treatment improves the metabolic phenotype by increasing fatty acid oxidation in skeletal muscle and suppressing hepatic glucose production. Muscle IGF-I receptor (IGF-IR)-lysine-arginine (MKR) mice expressing dominant-negative mutant IGF-IRs in skeletal muscle are diabetic with insulin resistance in muscle, liver, and adipose tissue. Adiponectin levels are elevated in MKR mice, suggesting an unusual discordance between insulin resistance and adiponectin responsiveness. Therefore, we investigated the metabolic actions of adiponectin in MKR mice. MKR and ob/ob mice were treated both acutely (28 µg/g) and chronically (for 2 wk) with full-length adiponectin. Acute hypoglycemic effects of adiponectin were evident only in ob/ob mice but not in MKR mice. Chronic adiponectin treatment significantly im- proved both insulin sensitivity and glucose tolerance in ob/ob but not in MKR mice. Adiponectin receptor mRNA levels and adiponectin-stimulated phosphorylation of AMPK in skeletal muscle and liver were similar among MKR, wild-type, and ob/ob mice. Thus MKR mice are adiponectin resistant despite normal expression of adiponectin receptors and normal AMPK phosphorylation in muscle and liver. MKR mice may be a useful model for dissecting relationships between insulin resistance and adiponectin action in regulation of glucose homeostasis. [ABSTRACT FROM AUTHOR]

The antiobesity and antidiabetic effects of the β3-adrenergic agonists were investigated on nonobese type 2 diabetic MKR mice after injection with a β3-adrenergic agonist, CL-316243. An intact response to acute CL-316243 treatment was observed in MKR mice. Chronic intraperitoneal CL-316243 treatment of MKR mice reduced blood glucose and serum insulin levels. Hyperinsulinemic euglycemic clamps exhibited improvement of the whole body insulin sensitivity and glucose homeostasis concurrently with enhanced insulin action in liver and adipose tissue. Treating MKR mice with CL-316243 significantly lowered serum and hepatic lipid levels, in part due to increased whole body triglyceride clearance and fatty acid oxidation in adipocytes. A significant reduction in total body fat content and epididymal fat weight was observed along with enhanced metabolic rate in both wild-type and MKR mice after treatment. These data demonstrate that β3-adrenergic activation improves the diabetic state of nonobese diabetic MKR mice by potentiation of free fatty acid oxidation by adipose tissue, suggesting a potential therapeutic role for β3-adrenergic agonists in nonobese diabetic subjects. [ABSTRACT FROM AUTHOR]

Discusses the deficiency of the circulating insulin-like growth factor system associated with inactivation of the acid-labile subunit gene. Case report of a 17-year-old boy who had a delayed onset of puberty; Methods of study; Results of the tests done on the boy; Possible reasons for the onset of the disease.

Pheochromocytomas/paragangliomas (PCCs/PGLs) are rare neuroendocrine tumors, developed from chromaffin cells derived from the neural crest. From a genetic point of view PCCs/PGLs are divided as sporadic cases, and inherited cases as part of hereditary (familial) syndromes. While the majority is benign, up to 26% of PCCs/PGLs will undergo malignant transformation. Validated prognostic pathological parameters for malignant PCCs/PGLs are still lacking. Signaling that follows the interactions between IGFs and their receptor/s in tumor cells received extensive attention when investigating the role of IGF1R in cancer. Increased IGF1R expression has been shown during progression to metastatic phenotypes and associated with worse prognosis in several types of cancer. In this review we provide evidence supporting a role for the IGFs system on PCC/PGL tumor biology and malignant behavior, endocrine actions to sustain tumor phenotype as well as heterotypic interaction´s regulation by IGF1, encouraging further research for targeted therapeutic options for these tumors., (Copyright© of YS Medical Media ltd.)

Several lines of evidence support an important role for the insulin-like growth factor system in breast cancer. Alterations in insulin-like growth factor I receptor (IGF-IR) have been associated with breast cancer metastasis; however, the specific role played by the IGF-IR in this process remains unclear. To address this issue, we evaluated MCF-7 breast cancer cells stably transfected either with an antisense construct to the IGF-IR, which reduced the expression of the IGF-IRs by approximately 50% (SX13 cells), or with the empty vector as control (NEO cells). Using functional assays for motility, attachment, and aggregation, we found a 3-fold increase in migration using both the wounding assay and the Boyden chamber migration assay. In addition, the SX13 cells attached less, and there was a reduction in cellular aggregation. These functional changes were accompanied by approximately 50% decrease in expression of E-cadherin and approximately 80% increase in p120 protein levels. Moreover, there was a significant reduction in p120 present in the E-cadherin-catenin-p120 complex. There was a 2-fold increase in active Rac1 and Cdc42 and a 35% decrease in active Rho in the SX13 cells. Our findings strongly suggest that the IGF-IR plays a role in the stabilization of the E-cadherin-catenin complex, thereby providing one possible explanation for the association between low levels of IGF-IR and a higher risk of mammary tumor metastasis.