全反式维甲酸联合替莫唑胺对胶质瘤U251细胞增殖与凋亡的影响

目的：研究全反式维甲酸（ATRA）联合替莫唑胺（TMZ）对胶质瘤细胞株U251增殖及凋亡的影响。方法：体外培养胶质瘤细胞株U251，分为ATRA组、TMZ组、ATRA＋TMZ组和空白对照4组，应用MTT法测定U251细胞生长抑制率，流式细胞仪检测细胞周期分布和细胞凋亡率，westernblot法检测细胞维甲酸受体β（RARβ）蛋白和凋亡相关蛋白Caspase．3蛋白的表达情况。结果：对照组、ATRA组、TMZ组及ATRA＋TMZ组的细胞生长抑制率分别为（1．72±0．12）％、（9．87±0．87）％、（23．87＋1．32）％及（35．74±1．44）％，ATRA＋TMZ组的细胞生长抑制率显著高于单独应用TMZ（P〈0．01）。对照组、ATRA组、TMZ组及ATRA＋TMZ组的细胞凋亡率分别为（1．32±0．11）％、（4．16±0．35）％、（8．44±0149）％、（15．27±1．03）％，ATRA＋TMZ组的凋亡率显著高于单独应用TMZ有更高的凋亡率（P〈0．01）。对照组、ATRA组、TMZ组及ATRA＋TMZ组RARp蛋白相对表达量分别0．452±0．054、0．837±0．068、0．195±0．021、0．376±0．039，ATRA＋TMZ组RARβ蛋白相对表达量显著高于TMZ组（P〈0．01）。ATRA＋TMZ组Caspase．的3蛋白表达相对水平为（0．832±0．059），明显高于ATRA组（0．334±0．041）及TMZ组（0．521＋0．032），差异具有统计学意义（P〈0．01）。结论：全反式维甲酸联合替莫唑胺能更有效抑制U251细胞的增殖，增加其凋亡率，这可能与其增加RARβ和Caspase-3蛋白的表达抑制U251细胞增殖、诱导细胞凋亡有关。

Effect of All-trans Retinoic Acid and Temozolomide on the Proliferation and Apoptosis in Human Glioma Cell Line U251

Objective： To evaluate the effect of combined therapy of all-trans retinoic acid （ATRA） and temozolomide（TMZ） on the growth inhibition and apoptosis of human glioma U251 cells. Methods： MTT assay was used to observe the effect of ATRA group, TMZ group, ATRA ＋ TMZ group and control group on the growth of U251 cell lines. Flow cytometry was used to determine the cell cycle distribution and the rate of apoptosis in 48 h.The expression of RARI3 and Caspase-3 proteins were detected by Western blot. Results： The results of MTT showed that the inhibitory rate of control group, ATRA group, TMZ group, ATRA ＋ TMZ group was （1.72 ± 0.12）%, （9.87± 0.87）%, （23.87 ± 1.32）%, （35.74 ± 1.44）%, respectively. The inhibitory rate of ATRA＋TMZ group was significantly higher than other groups （P〈0.01）. It was indicated that the combined therapy of TMZ and ATRA could significantly reduce the U251 cell proliferation. By the flow cytometry＇s test, the apoptotic rate of control group, ATRA group, TMZ group and the ATRA＋TMZ group was （1.32±0.11）%, （4.16± 0.35）%, （8.44±0.49）% and （15.27±1.03）% respectively. Statistical analysis showed the apoptotic rate of ATRA group and TMZ group was statistically significant higher than that of the control group, and the apoptotic rate of ATRA＋TMZ group was statistically significant higher than those of the ATRA group and the TMZ group （P〈0.01）. Western blot showed that the expression of RARI3 protein in control group, ATRA group, TMZ group, ATRA＋TMZ group was 0.452± 0.054, 0.837± 0.068, 0.195± 0.021, 0.376±0.039, respectively. The expression of RARβ protein in ATRA＋TMZ group was significantly higher than those of the control group and the TMZ group （P〈0.01）. The expression of Caspase-3 protein in control group, ATRA group, TMZ group, ATRA＋TMZ group was 0.142± 0.012, 0.334± 0.041, 0.521± 0.032, 0.832± 0.059, respectively. The expression of Caspase-3 protein in ATRA＋TMZ group was significantly higher than other groups（P〈0.01）. Conclusions： The combination therapy of TMZ and ATRA could effectively improve the sensitivity of U251 cells to TMZ by inhibiting U251 cells＇ proliferation and promoting U251 cells＇ apoptosis. The mechanism may be related to the increase of RARβ and Caspase-3 proteins.