肝癌细胞放射敏感性与survivin蛋白表达的关系

目的 探讨肝癌细胞放射敏感性与survivin表达的关系.方法 肝癌细胞HepG2和SMMC-7721在接受不同剂量γ射线照射后,分别采用克隆形成法、免疫细胞化学法、流式细胞术、比色法等检测细胞存活率、survivin蛋白表达、细胞周期变化和Caspase-3活性.结果 在2Gy照射下HepG2和SMMC-7721细胞的存活分数分别为0.43±0.01与0.70±0.02,SMMC-7721较HepG2放射抗拒.γ射线对SMMC-7721细胞的G2/M期阻滞时间较HepG2细胞长(48 h对24 h),在阻滞峰各剂量点SMMC-7721细胞的G2/M期比例也更高.γ射线可上调两株肝癌细胞survivin蛋白的表达,照射后48～72 h,SMMC-7721细胞的survivin蛋白表达水平显著高于HepG2细胞(t值为2.81～5.20,P值均＜0.05).而Caspase-3的活化水平在放射敏感的HepG2细胞中更高(t值为6.05～6.72,P值均＜0.01).结论 射线诱导的survivin表达上调及survivin对Caspase-3的负调控可能是SMMC-7721细胞较HepG2细胞放射抗拒的原因之一.

Relationship between the radiosensitivity of hepatic carcinoma cells and their survivin expression levels

OBJECTIVE: To investigate the relationship between the radiosensitivity of hepatic carcinoma cells and their survivin expression levels. METHODS: 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. RESULTS: 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). CONCLUSION: Survivin may play a critical role in mediating radiation resistance in SMMC-7721 through its up-regulation and caspase-3 dependent manner.