Abstract
Many studies have shown that insulin-like growth factors (IGF-I & IGF-II) are
implicated in the autocrine and paracrine growth of various tumors. Alterations
in serum IGFs and IGF-binding proteins (IGFBPs) profiles have been reported in
lung cancer. In this study, we measured serum levels of IGF-I and IGFBPs in 41
patients with lung cancer (small cell lung cancer, SCLC, 9; non-small cell lung
cancer, NSCLC, 32) by radioimmunoassay and Western ligand blot (WLB). The serum
IGF-I level in patients with lung cancer was significantly lower than in
controls (207.9±62.6 vs 281.3±53.9 ng/mL, p<0.01). Patients with NSCLC
showed significantly lower serum levels of IGF-I compared with SCLC patients
(194.0±62.9 vs 258.4±27.8 ng/mL, p<0.01). Patients with squamous cell
carcinoma tended to show lower serum levels of IGF-I than in those with
adenocarcinoma (187.9±63.6 vs 215.9±59.5 ng/mL, p>0.05). The concentration
of IGFBP-3 in lung cancer was 48% of that found in controls by WLB. The serum
level of IGFBP-2 was markedly elevated in patients with lung cancer compared
with controls (1303.7±618.0 vs 696.2±300.5, p<0.01). However, there was no
significant difference between SCLC and NSCLC groups. This result showed that
serum level of IGF-I/IGFBPs may be useful markers for diagnosing and identifying
tumor types in lung cancer and further studies are needed.