异黄酮增加前列腺癌细胞放射敏感性

Enhancing effect of isoflavonoid genistein on radiosensitivity of DU145 prostate cancer cells

目的 :研究异黄酮 ( genistein)与辐射联合应用对 DU14 5前列腺癌细胞放射敏感性的影响。方法 :雄激素非依赖型 DU14 5前列腺癌细胞在克隆形成试验中 ,接受不同浓度的 genistein和 /或合用辐射 ,比较 DU14 5细胞的存活率 ;用 DNA Ladder检测细胞凋亡 ,并辅以 TUNEL法观察凋亡形态 ;流式细胞仪和免疫印迹法分别观察细胞周期改变和相关蛋白表达。结果 :克隆形成试验显示 ,genistein在较低或中等浓度 ( 5～ 15μmol/ L )时 ,即可提高DU14 5细胞的放射敏感性 ;单独辐射和 /或合用 genistein 2 4 h后 ,细胞凋亡主要见于高浓度 genistein( >30μmol/L )处理组 ,72 h后凋亡亦见于较低浓度 genistein组 ;当 genistein与辐射合用时 ,可产生 G2 / M细胞周期阻滞 ,72 h后得到大部维持并伴有凋亡和超二倍体细胞群的出现 ;细胞周期相关蛋白分析提示 ,随着 genistein浓度的提高 ,周期素 B1呈明显双相改变 ,cdc- 2亦呈类似改变 ,但较轻微 ,而 p2 1cip1则稳步上升。结论 :genistein可提高 DU14 5前列腺癌细胞的放射敏感性 ,其机理可能与凋亡细胞的增加 。

Objective: To study the enhancing effect of isoflavonoid genistein in irradiation (IR) on prostate DU145 cancer cells. Methods: Prostate cancer cell line DU145 was used in this experiment. Clonogenic assay was applied to compare the survival fractions of DU145 cells after treatments with genistein alone and/or graded IR. DNA electrophoresis and TUNEL method were applied to detect cell apoptosis. Cell cycle was observed using flow cytometry and related protein expressions by immunoblotting. Results: Clonogenic assay demonstrated that genistein, even at low to medium concentrations, enhanced the radiosensitivity of DU145 cells. After treatments with IR and/or genistein for 24 h, apoptosis was mainly seen with genistein at high concentration and was minimally dependent on IR. Apoptosis also occurred after treatments for 72 h with lower concentrations of genistein, especially when combined with IR. While IR or genistein led to a G2/M cell cycle arrest, combination of them could further increase DU145 cells at G2/M phase. This G2/M arrest was largely maintained at 72 h, and accompanied by increasing apoptosis and hyperdiploid cell populations. Cell-cycle related protein analysis disclosed biphasic changes in cyclin B1, less markedly increased cdc-2 and stably elevated p21 cip1 levels with increasing genistein concentrations. Conclusion: Genistein could enhance the radiosensitivity of DU145 prostate cancer cells. The mechanisms might be involved in the increased apoptosis, prolonged cell cycle arrest and impaired damage repair induced by the combined treatment.