Alterations in serum levels of insulin‐like growth factors and insulin‐like growth‐factor‐binding proteins in patients with colorectal cancer

Abstract

It has been reported that insulin‐like growth factor (IGF) II is associated with human primary colorectal tumors and colon‐carcinoma cell lines. Here, we examine alterations in circulating levels of IGFs and IGF binding proteins (IGFBPs) in patients with colorectal carcinoma, and compare them to age‐ and nutrition‐adjusted references. We report (i) an increase in serum IGF‐11 concentrations (about 2‐fold), whereas IGF‐1 concentrations are regarded as normal when aging is taken into account; (ii) an apparent increase in serum IGFBP‐3 levels when compared to those of healthy elderly subjects, IGFBP‐3 only being detected in the 150‐kDa IGFBP ternary complex as in normal serum; (iii) abnormally elevated serum IGFBP 2 levels taking into account the apparent concentrations of IGFBP‐3. This simultaneous elevation of IGFBP‐3 and IGFBP‐2 in the serum of patients with colorectal tumors appears to be unique in that it reflects a break in the inverse relationship between the serum IGFBP‐3 and IGFBP‐2 levels that is observed in normal and in several physiopathotogical conditions. Moreover, it enables a distinction to be made between 76.5% (13/17) of patients with colorectal carcinoma and normal adults, age‐related healthy aged and malnourished patients. We propose that the disturbed serum IGFBP profile observed in the patients with colorectal cancer may be a consequence of oversecretion of IGF‐11 by the tumor cells. The usefulness of IGFs and IGFBPs as potential colorectal tumor‐associated metabolic markers should be further investigated.