摘要： 目的 探讨替莫唑胺（TMZ）和甲泼尼龙（MP）对人胶质瘤细胞系U251 放射治疗敏感性的影响，以期为临床优化治疗方案提供依据。方法 经体外传代培养的U251 细胞根据治疗方案的不同，分为对照组、放射治疗（R）组、放射治疗+ 替莫唑胺（R + TMZ）组、放射治疗+ 甲泼尼龙（R + MP）组、放射治疗+ 替莫唑胺+ 甲泼尼龙（R + TMZ + MP）组，分别予以放射治疗（2 Gy/24 h）、替莫唑胺、甲泼尼龙及三者联合治疗。采用磺酰罗丹明B（SRB）比色法、流式细胞术和Western blotting 法分析U251 细胞增殖率和凋亡率，观察凋亡相关蛋白Bax 和Bcl-2 表达变化。结果 放射线照射联合甲泼尼龙治疗后，U251 细胞存活率明显升高（均P = 0.000）；但经体外培养24 和48 h 后，三者联合治疗组（R + TMZ + MP 组）U251细胞增殖率显著高于放射治疗联合替莫唑胺组（P = 0.000）。除对照组外，不同抗肿瘤治疗组U251 细胞凋亡率均呈现升高趋势（P = 0.000），但放射治疗联合甲泼尼龙组细胞凋亡率显著低于其他各组（均P =0.000）。经放射线照射联合替莫唑胺和三者联合治疗后，U251 细胞Bax 蛋白表达水平升高（P = 0.000），而放射线照射联合甲泼尼龙和三者联合治疗，Bcl-2 蛋白表达水平升高；其中以放射治疗联合替莫唑胺组Bax/Bcl-2 比值最高（P = 0.000），放射治疗联合甲泼尼龙组最低（P = 0.000）。结论 甲泼尼龙可以诱导人胶质瘤细胞产生放射抵抗，而替莫唑胺对甲泼尼龙诱导的放射抵抗具有增敏作用。提示：胶质母细胞瘤患者在应用甲泼尼龙减轻放射治疗不良反应过程中所诱导的放射治疗抵抗可通过同时应用替莫唑胺而抵消。

关键词: 神经胶质瘤, 替莫唑胺, 甲泼尼龙, 抗肿瘤联合化疗方案, 细胞凋亡, 流式细胞术, 细胞, 培养的, 体外研究

Abstract: Objective To investigate the effect of temozolomide (TMZ) and methylprednisolone (MP) on the radiosensitivity of human glioma cells (U251 cells), and to provide experimental evidence for optimal chemotherapy in malignant glioma. Methods Human U251 cells were used for this experiment, and treated respectively by 5 schemes: group C (control, not irradiated and no TMZ and MP), R (irradiated alone), R + TMZ (irradiated and TMZ), R + MP (irradiated and MP) and R + TMZ + MP (irradiated, TMZ and MP). Sulforhodamine B (SRB) assay was used to calculate the cell viability percentage. The apoptosis rate of U251 cells was determined by flow cytometry. The expression of Bax and Bcl-2 protein in the treated cells was detected by Western blotting. Results After treatment, the survival rate in group R + MP was significantly higher than group R, R + TMZ and R + TMZ + MP (P = 0.000, for all). The proliferation rate of group R + TMZ + MP at 24 and 48 h was higher than group R + TMZ (P = 0.000). The detection of apoptosis showed that the apoptosis rate in experimental groups increased obviously (P = 0.000, for all), but not in group C. In cell apoptosis elevated groups, the apoptosis rate of group R + MP increased less than group R, R + TMZ and R + TMZ + MP (P = 0.000, for all). The Bax expression in group R + TMZ and R + TMZ + MP was clearly higher than group C, R and R + MP (P = 0.000, for all). The Bcl-2 protein in group R + MP and R + TMZ + MP was expressed significantly higher than group C, R and R + TMZ (P = 0.000, for all). The highest Bax/Bcl-2 ratio was in group R + TMZ (P = 0.000), and the lowest Bax/Bcl-2 ratio was in group R + MP (P = 0.000). Conclusion MP could induce human glioma cells to resist radiation. TMZ could improve the radioresistant induced by MP. During the radiotherapy in malignant glioma, the radiation resistant effect induced by using MP to reduce radiotherapeutic adverse reaction could be offset by TMZ.

Key words: Glioma, Temozolomide, Methylprednisolone, Antineoplastic combined chemotherapy protocols, Apoptosis, Flow cytometry, Cells, cultured, In vitro