Effect of blocking IGF-Ⅰ receptor on growth of human hepatocellular carcinoma cells

AIM： To study the expression level and localization of insulin-like growth factor -Ⅰ receptor （IGF-IR） in HepG2 cells and Chang liver cells, and to observe the effect of anti-IGF-IR monoclonal antibody （αIR3） on the growth of HepG2 cells. METHODS： The expression of IGF-IR in HepG2 cells and Chang liver cells was detected by immunohistochemistry. The influences of αIR3 on proliferation and apoptosis were examined by the 3- （4, 5-dimethylthiazol-2-yl）-2, 5- diphenyltetrazolium bromide （MTT） assay and electron microscopy, respectively. Flow cytometry （FCM） was applied for the analysis of cell cycle and apoptosis was observed under electron microscope. RESULTS： IGF-IR was located in the membranes of both HepG2 and Chang liver cell lines, and the expression level of IGF-IR was higher in HepG2 cells than in Chang liver cells. Treated with 0.1 μg/mL αIR3 for 48 h in vitro, the cell growth index （GI） of HepG2 cells was significantly higher than that of control （103.41% ys 100%, P 〈 0.01）. However, the αIR3 for 24 h at final concentration of 4.0 μg/mL made the GI of HepG2 cells lower than that of control （93.37% vs 100%, P 〈 0.01）. Compared with control, treated with αIR3 for 48 h at final concentrations ranging from 2.0 μg/mL to 4.0 μg/mL markedly reduced the GIs of HepG2 cells （97.63%, 97.16%, 95.13%, 92.53% vs 100%, P 〈 0.05 or P 〈 0.01）, treated with αIR3 for 72 h at final concentrations ranging from 0.2 μg/mL to 4.0 μg/mL decreased the GIs of HepG2 cells obviously （95%, 91.63%, 90.77%, 89.84%, 88.51% vs 100%, P 〈 0.01）, and treated with αIR3 for 96 h at final concentrations ranging from 0.5 μg/mL to 4.0 μg/mL made GIs of HepG2 cells lower significantly （88.86%, 83.97%, 79.81%, 77.24%, 70.51% vs 100%, P 〈 0.05or P 〈 0.01）. Moreover, treated with αIR3 from 24 h to 96 h at final concentrations ranging from 0.2 μg/mL to 4.0 μg/mL reduced the GI of HepG2 cells from 97.63% to 70.51% in a dose- and time-dependent manner. Also, αIR3 treatment for 72 h at final concentration from 0.5 μg/mL to 2.0 μg/mL increased the proportion of G0/G1 phase cells（61.73%, 67.1%, 83.7%,76.87% vs 44.47%, P 〈 0.01） and significantly decreased that of S phase cells（28.63%, 25.13%, 15.63%, 23.13% vs 53.17%, P 〈 0.01）, in contrast to the proportion of G2/M phase cells. The apoptotic rates of HepG2 cells were increased more than that of control （7.83%, 16.13%, 21.1%, 37.73% vs 4.13%, P 〈 0.01）. CONCLUSION： The malignant cell phenotype of human hepatocarcinoma cell is related to overexpression