Increased insulin-like growth factor 1 receptor (IGF1R) expression in small cell lung cancer and the effect of inhibition of IGF1R expression by RNAi on growth of human small cell lung cancer NCI-H446 cell

Insulin-like growth factor 1 receptor (IGF1R) is a tyrosine kinase receptor implicated in tumourigenesis that may be an attractive target for anti-cancer treatment. In this study, the expression and clinical significance of IGF1R were investigated in serum and lung cancer tissues from small cell lung cancinoma (SCLC). We also compared the effect of IGF1R up-regulation and IGF1R inhibition on viability and apoptosis of NCI-H446 cells. We found the concentration of IGF1R in blood serum was significantly increased and positive IGF1R protein in cancer tissue was more prevalent in SCLC. A statistically significant correlation among IGF1R-positve tumors, lymph node metastasis and local invasion was discussed. Furthermore, IGF1R overexpression lead to an increase of cell survival and suppressed cell apoptosis, IGF1R silencing mediated by RNAi abrogate this response of NCI-H446 cells. Our results further demonstrated that the effects of these treatments may be assigned to the effective inhibition of lung cancer cells from Akt/P27(Kip1) pathway in IGF-1R signaling. These features may have important implications for future anti-IGF1R therapeutic approaches.