Bexarotene协同TRAIL对白血病细胞株KG1a的凋亡诱导作用

目的 探讨bexarotene联合肿瘤坏死因子相关凋亡诱导配体（TRAIL）对白血病细胞株KG1a凋亡的影响，并初步探讨其作用机制。方法 取对数生长期KG1a，根据不同处理方式分为TRAIL组、bexarotene组、300 ng/mL TRAIL联合bexarotene组和2.0 μmol/L bexaroten联合TRAIL组。流式细胞仪检测各组细胞凋亡率。以先加bexarotene或TRAIL孵育，后加TRAIL或bexarotene处理设计序贯实验，流式细胞仪检测细胞凋亡率。Western blotting分析KG1a细胞型自杀相关因子(Fas)相关死亡域样白介素-1β转换酶抑制蛋白(c-FLIP)表达变化。结果 TRAIL和bexarotene组的各浓度组间（bexarotene 2.0 μmol/L除外）细胞凋亡率比较，差异无统计学意义（P>0.05）；两联合用药组的细胞凋亡率均明显高于相应浓度的TRAIL组和bexarotene组(P<0.01)。序贯实验表明，bexarotene具有逆转KG1a对TRAIL耐药的作用（P<0.001）。与2.0 μmol/L bexarotene 或300 ng/mL TRAIL 单独用药比较，两者联合应用能显著下调c-FLIP表达（P<0.05）。结论 Bexarotene能显著增强TRAIL对KG1a的诱导凋亡作用，下调c-FLIP表达是协同作用的可能机制。

Synergic effects of bexarotene and TRAIL on apoptosis of leukemic cell line KG1a

Objective To explore the effects and mechanism of bexarotene in combination with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on apoptosis of leukemic cell line KG1a. Methods KG1a cells at logarithmic growth phase were obtained, and were divided into TRAIL group, bexarotene group, 300 ng/mL TRAIL in combination with bexarotene group and 2.0 μmol/L bexaroten in combination with TRAIL group. Cell apoptosis rate was detected in each group by flow cytometry. Flow cytometry was also employed to determine the apoptosis rates of KG1a cells after treatment with bexarotene and TRAIL in different sequences. The expression of Fas associated death domain-like IL-1 beta converting enzyme inhibitory protein (c-FLIP) was detected by Western blotting. Results There was no significant difference in cell apoptosis rates between TRAIL group and bexarotene group of each concentration (except for bexarotene 2.0 μmol/L) (P > 0.05). The cell apoptosis rates of 300 ng/mL TRAIL in combination with bexarotene group and 2.0 μmol/L bexaroten in combination with TRAIL group were significantly higher than those in TRAIL group and bexarotene group of each corresponding concentration (P <0.01). Sequential analysis revealed that bexarotene could reverse the resistance of KG1a cells to TRAIL (P < 0.001). Compared with single use of 2.0 μmol/L bexarotene or 300 ng/mL TRAIL, combination use could significantly down-regulated the expression of c-FLIP (P < 0.05). Conclusion Bexarotene can significantly enhance the apoptosis of KG1a cells induced by TRAIL, which may be attributed to the down-regulation of c-FLIP expression.