Elevated Insulin-Like Growth Factor-1 and Insulin-Like Growth Factor Binding Protein-2 in Malignant Pleural Effusion

Abstract

Insulin-like growth factor-1 (IGF-1) and its binding proteins (IGFBPs) are produced by many tissues and are present in serum and other biological fluids. Alterations in sera of IGF-1 and 2 and IGFBPs were demonstrated in patients with malignancy, infection and other diseases causing pleural effusion. In this study the IGF-1 and IGFBP-2 content and the specific electrophoretic patterns of IGFBPs in samples of sera and pleural effusions of 25 patients with malignancy, infection and congestive heart failure were investigated. IGF-1 levels in exudative effusions of malignant solid tumors were significantly higher [(mean &#45 SD), 20.9 &#45 7.5 nmol/L, n=9] than in lymphoma (11.0 &#45 5.2 nmol/L, n=5; p<0.05), infection (11.4 &#45 6.5 nmol/L, n=6; p<0.05) and transudative effusion of congestive heart failure (4.3 &#45 3.3 nmol/L, n=5; p<0.02). IGFBP-2 was markedly increased in effusions of malignant solid tumors (2.14 &#45 0.82 mg/L, n=9) compared with exudates of lymphoma, infection and transudates (1.10 &#45 0.70, 1.22 &#45 0.32 and 0.93 &#45 0.52 nmol/L, respectively, p<0.05). Moreover, in effusion of solid tumors, IGFBP-2 levels were higher than those in corresponding sera, which suggests local production of this binding protein. The demonstration of IGFBP-2 in solid tumor cells by immunohistochemistry further supports this possibility. This work demonstrates the existence of the IGF-1/IGFBP system in pleural fluids from different etiologies and implies possible use of IGF-1 and IGFBP-2 as a potential marker of malignant effusions.