Correlation between insulin-like growth factor binding protein-3 serum level and melanoma progression

Abstract

Insulin-like growth factor (IGF) binding protein (IGFBP)-3 is the main carrier of circulating IGFs and the main modulator of their activity. IGFBP-3 controls cellular availability of IGFs, which cannot exert their pro-proliferative activity while bound to IGFBP-3. Proteolysis of IGFBP-3 is one mechanism to control IGF release. A reduction of serum IGFBP-3 levels and the associated increased availability of IGFs may represent a strategy whereby melanoma increases its metastatic potential. The aim of our study was to evaluate the correlation between the IGFBP-3 serum level and melanoma stage. The study included 41 patients, 24 male and 17 female, with median age of 60 years (range 24-80), affected by cutaneous melanoma. Blood samples were taken from each patient and IGFBP-3 serum levels were measured using Western blot analysis with commercial antibodies. Values were normalized using commercial IGFBP-3. The statistical analysis showed that full-size, glycosylated IGFBP-3 concentrations were significantly lower in the sera of patients with stage IV melanoma. Low serum levels of IGFBP-3 correlated with both disease progression and presence of disease at the time of sample collection. In patients who underwent follow-up visits with further collections of blood samples, the concentrations of glycosylated IGFBP-3 decreased only in those who showed progression of disease. Our study shows only preliminary results on a limited number of patients. We demonstrate that there is a significant inverse correlation between the serum concentration of full-size, glycosylated IGFBP-3 and disease progression in patients with melanoma.