Insulin like growth factors axis and growth disorders

Selective Insulin-like Growth Factor Resistance Associated with Heart Hemorrhages and Poor Prognosis in a Novel Preclinical Model of the Hematopoietic Acute Radiation Syndrome

Although bone marrow aplasia has been considered for the past decades as the major contributor of radiation-induced blood disorders, cytopenias alone are insufficient to explain differences in the prevalence of bleeding. In this study, the minipig was used as a novel preclinical model of hematopoietic acute radiation syndrome to assess if factors other than platelet counts correlated with bleeding and survival. We sought to determine whether radiation affected the insulin-like growth factor-1 (IGF-1) pathway, a growth hormone with cardiovascular and radioprotective features. Gottingen and Sinclair minipigs were exposed to ionizing radiation at hematopoietic doses. The smaller Gottingen minipig strain was more sensitive to radiation; differences in IGF-1 levels were minimal, suggesting that increased sensitivity could depend on weak response to the hormone. Radiation caused IGF-1 selective resistance by inhibiting the anti-inflammatory anti-oxidative stress IRS/PI3K/Akt but not the pro-inflammatory MAPK kinase pathway, shifting IGF-1 signaling towards a pro-oxidant, pro-inflammatory environment. Selective IGF-1 resistance associated with hemorrhages in the heart, poor prognosis, increase in C-reactive protein and NADPH oxidase 2, uncoupling of endothelial nitric oxide synthase, inhibition of nitric oxide (NO) synthesis and imbalance between the vasodilator NO and the vasoconstrictor endothelin-1 molecules. Selective IGF-1 resistance is a novel mechanism of radiation injury, associated with a vicious cycle amplifying reactive oxygen species-induced damage, inflammation and endothelial dysfunction. In the presence of thrombocytopenia, selective inhibition of IGF-1 cardioprotective function may contribute to the development of hemostatic disorders. This finding may be particularly relevant for individuals with low IGF-1 activity, such as the elderly or those with cardiometabolic dysfunctions.

The Effect of Metformin as an Adjunct Therapy in Adolescents with Type 1 Diabetes

INTRODUCTION

The strict control of blood glucose levels in adolescents with Type 1 Diabetes Mellitus (T1DM) is accompanied with a considerable long term decrease in microvasular and macrovascular complications.

AIM

This study was conducted to investigate the effect of metformin as an adjunct therapy in adolescents with poorly controlled Type 1 diabetes.

MATERIALS AND METHODS

It was a quasi-experimental (an uncontrolled before and after) study. The study population consisted of the patients aged over 10 years with T1DM. Metformin tablet was added to patient's insulin therapy for 12 months. Haemoglobin A1c protein was measured in the beginning of the study and repeated with three months intervals till the end of it. Insulin dosage, Body Mass Index (BMI), serum lipid, creatinine and lactate level were measured twice; in the beginning of the study and at the end of it (after 12 months). Data was analysed by SPSS (version 18) software. Paired- t-test, Wilcoxon signed ranks test and Repeated Measure ANOVA were used to examine the study's hypothesis. A p-value <0.05 was considered as significant.

RESULTS

Twenty nine patients were included in the study. HbA1c level and insulin dosage was significantly reduced (p<0.001) after one month of metformin as an adjunct therapy. Serum lipid was decreased (p=0.7). Weight (p<0.001) and BMI (p=0.007) were increased.

CONCLUSION

Adjunctive metformin therapy reduced HbA1c value and the insulin dosage received in adolescents with T1DM.

Growth failure in children with chronic myeloid leukemia receiving imatinib is due to disruption of GH/IGF-1 axis

BACKGROUND

The frontline treatment for chronic myeloid leukemia (CML) is tyrosine kinase inhibitor therapy. There is increasing evidence that imatinib results in growth failure in children; etiology is unclear.

PROCEDURE

The cross-sectional study was conducted from January 2011 to June 2012 in a pediatric oncology unit. Patients with chronic-phase CML, receiving imatinib for more than 6 months were enrolled. Growth hormone (GH): Insulin like growth factor-1 (IGF-1) axis was evaluated by GH stimulation test by insulin tolerance and clonidine stimulation test, among other hormonal assays.

RESULTS

Eighteen patients with a median age of 12.9 years (range 6.5-17) completed the study. The mean duration of imatinib therapy was 43.7 ± 32.8 months. The height-for-age z-scores at the start of imatinib and at enrollment were -1.07 ± 0.88 and -1.8 ± 0.98, respectively (P < 0.001). Seven (39%) patients were GH deficient and lacked a sufficient response to either of the two stimulation tests. Majority, 16 (89%) patients had IGF-1 z-scores less than the mean. IGFBP-3 levels were below the mean in all patients. Every patient had deficiency of either GH, or IGF-1, or both. Bone age was delayed in 7 (39%).

CONCLUSIONS

This study demonstrates that imatinib results in growth failure in children with CML by disturbing the GH:IGF-1 axis. GH stimulation test and serum IGF-1 levels should be performed in children on treatment with imatinib who have growth retardation. Future studies should evaluate the role of recombinant GH therapy for ameliorating the adverse effect on growth.

Expression patterns of insulin-like growth factor system members and their correlations with growth and carcass traits in Landrace and Lantang pigs during postnatal development

The IGF system plays important roles in growth. Nevertheless, few data have been reported so far on the expression of IGF system members and their relationship with growth in domestic animals, especially pigs. In this study, hepatic transcript level of IGF1, IGF2, IGF binding protein 2 (IGFBP2), IGFBP3 and IGF 1 receptor (IGF1R), plasma protein level of IGF1 and IGFBP3, and eight growth or carcass traits, including chest circumference, body length, body height (BH), body weight, carcass weight, loin muscle area (LMA), back fat thickness and average daily gain, were measured in fast-growing Landrace and slow-growing Lantang pigs at the age of 1, 27, 90, 150 and 180 days. The results showed that liver mRNA level of IGF1, IGF2 and IGF1R, and blood protein level of IGF1 have a similar developmental profile in both Landrace and Lantang pigs. Their levels were higher at the early age than that at other older ages. Hepatic transcript abundances of the two growth inhibitors, IGFBP2 and IGFBP3, were mostly higher in Lantang pigs than that in Landrace pigs, at 5 examined postnatal stages. The IGF system members' liver mRNA level and/or serum protein level have significant correlation with each other in different age of Landrace or Lantang pigs. Hepatic mRNA level or serum protein level of IGF system members also has significant correlation with investigated traits, especially with BH and LMA, in different age of Lantang or Landrace pigs. Our results revealed the change profiles of porcine IGF system members' liver transcript level and plasma protein level between different pig breeds and different postnatal developmental ages. Moreover, the correlation analysis results suggest that the IGF system members act coordinately to regulate the growth performance and carcass composition in pigs. The information obtained from the present study is important for elucidation of the regulatory mechanism of IGF system underlying growth, and for genetic improvement in pigs.

Urinary insulin-like growth factor 2 identifies the presence of urothelial carcinoma of the bladder

OBJECTIVE

To examine urinary insulin-like growth factor 2 (IGF-2) levels in patient urine samples and determine the potential of IGF-2 as a marker for the presence of urothelial carcinoma of the bladder (UCB).

PATIENTS AND METHODS

The current gold standard for diagnosis of UCB is cystoscopy and cytological analysis. The identification of an accurate urine marker for UCB with the potential to replace unnecessary cystoscopy would benefit patients with UCB and others investigated after detecting haematuria. In the present study, we analysed 65 urine samples, and optimized an enzyme-linked immunosorbent assay-based approach to measure urinary levels of IGF-2.

RESULTS

Based on a threshold of 5.4 ng/mL, patients with UCB have significantly elevated levels of urinary IGF-2 (P = 0.009) and this difference remained significant after adjustment for age and sex (P = 0.04). Sensitivity and specificity values of 80% and 52%, respectively, were determined for urinary IGF-2 alone and when combined with nuclear matrix protein 22 (NMP22; an approved biomarker for detection of UCB). There was a positive correlation between urinary IGF-2 levels and NMP22 levels in patient urine samples and the combined assay improved the detection of UCB (sensitivity 85% and specificity 52%).

CONCLUSION

Substantiated evidence has identified IGF-2 as a valuable marker for UCB. In addition, the novel observations of the present study have shown that aberrant levels of IGF-2 occurring in the presence of UCB, can now be determined through a simple and inexpensive urine assay.