ABSTRACT
<p><b>OBJECTIVE</b>To investigate the relationship between the radiosensitivity of hepatic carcinoma cells and their survivin expression levels.</p><p><b>METHODS</b>Hepatic carcinoma cell lines HepG2 and SMMC-7721 were irradiated with various doses of 60Co gamma-rays. The cell survival rate, expression of survivin, cell cycle profile and activity of caspase-3 were respectively detected by clonogenic assay, immunocytochemistry, flow cytometry and chromatometry.</p><p><b>RESULTS</b>The surviving fraction at 2Gy (SF2) of HepG2 and SMMC-7721 were 0.43+/-0.01 vs 0.70+/-0.02, and HepG2 had higher radiosensitivity than SMMC-7721. gamma-rays radiation up-regulated the expression of survivin. SMMC-7721 had a significantly higher expression of survivin than HepG2 (t = 2.81-5.20, P < 0.05). The activity of caspase-3 was more powerful in HepG2 than in SMMC-7721 (t = 6.05-6.72, P < 0.01).</p><p><b>CONCLUSION</b>Survivin may play a critical role in mediating radiation resistance in SMMC-7721 through its up-regulation and caspase-3 dependent manner.</p>