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目的研究凋亡抑制基因Survivin的表达与EGCG对鼻咽癌CNE-2裸鼠移植瘤放疗增敏作用的关系。方法将低分化鼻咽癌细胞CNE-2接种于4~6周龄的雌性裸鼠皮下,待移植瘤生长至4~6 mm时,随机分为4组,分别采用NS、EGCG[50 mg/(kg.w)]、放疗(15 Gy)、EGCG给药24 h后再行放疗等方法分别处理各组裸鼠,处理前后分别测量裸鼠移植瘤的短径、体积。21 d后处死裸鼠,取出肿瘤并称重,将肿瘤组织分成两份,分别用来进行病理切片TUNEL染色以及RT-PCR检测Survivin mRNR的表达。结果EGCG+放疗对裸鼠移植瘤的生长抑制最为明显,肿瘤生长抑制率为89.3%,消退率为40.0%。与对照组EGCG组、放疗组相比,EGCG+放疗组的凋亡指数均明显增加(P<0.05),同时,伴有Survivin mRNR的表达显著下降(P<0.05)。结论EGCG对鼻咽癌裸鼠移植瘤可能具有放疗增敏作用,这种作用可能与凋亡抑制基因Survivin的表达下调有关。
Objective To study the relationship between the expression of Survivin, an inhibitor of apoptosis, and the sensitization effect of EGCG on the radiosensitization of nasopharyngeal carcinoma CNE-2 xenografts in nude mice. Methods The poorly differentiated nasopharyngeal carcinoma cell line CNE-2 was inoculated subcutaneously into 4 to 6-week-old female nude mice. When the transplanted tumor grew to 4 to 6 mm, it was randomly divided into 4 groups: NS, EGCG [50 mg / (kg.w)], radiotherapy (15 Gy), and 24 h after EGCG administration. The nude mice were also treated by radiotherapy and other methods. The short diameter and volume of the xenografted tumor were measured before and after treatment. Twenty-one days later, the nude mice were sacrificed and the tumors were removed and weighed. The tumor tissues were divided into two groups and used to detect the expression of mRNR in Survivin by TUNEL staining and RT-PCR respectively. Results EGCG + radiotherapy had the most obvious inhibitory effect on the growth of xenografts in nude mice. The tumor growth inhibition rate was 89.3% and the regression rate was 40.0%. Compared with the EGCG group and radiotherapy group, the apoptosis index of EGCG + radiotherapy group was significantly increased (P <0.05), while the expression of mRNR with Survivin was significantly decreased (P <0.05). Conclusion EGCG may radiosensitize nasopharyngeal carcinoma xenografts in nude mice, which may be related to the down-regulation of Survivin.