Expression of genes encoding IGF1, IGF2, and IGFBPs in blood of obese adolescents with insulin resistance

Abstract Objective. The development of obesity and its metabolic complications is associated with dys-regulation of various intrinsic mechanisms, which control basic metabolic processes via changes in the expression of numerous regulatory genes. The main goal of this work was to study the association between the expression of insulin-like growth factors (IGF1 and IGF2) and IGF-binding proteins and insulin resistance in obese adolescents for evaluation of possible contribution of these genes in development of insulin resistance. Methods. The expression of IGF1, IGF2, and IGFBPs mRNA was measured in blood of obese adolescents with normal insulin sensitivity and insulin resistance in comparison with the normal (control) individuals. Results. In the blood of obese adolescents with normal insulin sensitivity the expression of IGFBP4 , IGFBP5 and HTRA1 genes was down-regulated, but IGFBP2 and IGFBP7 genes up-regulated as compared to control (normal) group. At the same time, no significant changes in IGF1 and IGF2 gene expressions in this group of obese adolescents were found. Insulin resistance in obese adolescents led to up-regulation of IGF2 , IGFBP2 , and IGFBP7 gene expressions as well as to down-regulation of the expression of IGF1 , IGFBP5 and HTRA1 genes in the blood in comparison with the obese patients, which have normal insulin sensitivity. Furthermore, the level of IGFBP4 gene expression was similar in both groups of obese adolescents. Conclusions. Results of this investigation provide evidence that insulin resistance in obese adolescents is associated with gene specific changes in the expression of IGF1 , IGF2 , IGFBP2 , IGFBP5 , IGFBP7 , and HTRA1 genes and these changes possibly contribute to the development of glucose intolerance and insulin resistance.