塞来昔布对FaDu人咽鳞癌裸鼠移植瘤放疗过程中肿瘤再增殖抑制效应

Effect of celecoxib on inhibiting FaDu squamous cell carcinoma repopulation during radiotherapy in nude mice xenografts

目的前期基础实验研究通过病理证实,FaDu人咽鳞癌裸鼠移植瘤在放疗过程中会出现肿瘤的加速再增殖。国内外许多基础及临床研究发现选择性环氧化酶-2(cyclooxygenase-2,COX-2)抑制剂有提高放疗疗效的作用。本研究以前期证实的肿瘤再增殖模型为基础,探索选择性COX-2抑制剂塞来昔布(celecoxib,CCX)对放疗过程中肿瘤细胞再增殖的抑制作用及其潜在机制。方法建立FaDu人咽鳞癌裸鼠移植瘤模型,随机分为对照组、单用CCX组、单纯放疗组及CCX联合放疗组。CCX 0.2 mL/只,100 mg/kg,灌胃给药。放疗方式采用常规分割放射治疗,6 MeV电子线,2.0Gy/次,每日或隔日照射,共给予12~18次照射。治疗期间每3d测量1次肿瘤体积。在各组实验结束后处死裸鼠,获取肿瘤行免疫组化检测增殖指标Ki-67和和溴化脱氧尿嘧啶核苷(bromodeoxyuridine,BrdUrd)、表皮生长因子受体(epithelial growth factor receptor,EGFR)及凋亡相关蛋白(Caspase-3)表达的变化。结果肿瘤生长曲线表明,与对照组比较,3组实验组均能抑制肿瘤体积的增长,但联合治疗组的肿瘤体积增长更缓慢。与单纯放疗组比较,Ki-67标记指数在CCX联合放疗组出现明显降低(12f/24d+CCX组,t=5.666,P=0.004;18f/36d+CCX组,t=2.572,P=0.042)。BrdUrd标记指数在CCX联合放疗组出现明显降低(12f/24d+CCX组,t=5.930,P=0.001;18f/36d+CCX组,t=5.430,P=0.006)。EGFR表达在CCX联合放疗组出现明显降低(12f/24d+CCX组,Z=-0.281,P=0.037;18f/36d+CCX组,Z=-2.048,P=0.031)。与单纯放疗组相比,联合治疗组的Caspase-3表达出现明显增高(12f/24d+CCX组,Z=-2.92,P=0.05;18f/36d+CCX组,Z=-2.739,P=0.006)。结论通过组织病理证实了FaDu人咽鳞癌荷瘤裸鼠在放疗过程中出现了加速再增殖。CCX联合放疗能够显著抑制肿瘤体积增长,说明CCX能够增强放疗的放射敏感性,值得临床进一步研究。

OBJECTIVE FaDu human squamous cell carcinoma（FaDu-hSCC）demonstrated accelerated tumor repopulation during fractionated irradiation with pathological validation in a xenograft model system.Previous studies showed that the selective cyclooxygenase-2（COX-2）inhibitor celecoxib can enhance the tumor response to radiotherapy.So we aimed to explore the effect of celecoxib in inhibiting repopulation of FaDu tumors in nude mice during fractionated radiotherapy and the potential mechanism.METHODS To establish the nude mice xenograft model,mice were randomized to control groups,celecoxib or irradiation alone groups and celecoxib＋irradiation groups.Celecoxib [100 mg/kg（0.2 mL）]was administrated by daily gavage.Irradiation was delivered with 12 to 18 fractions of 2.0 Gy daily or every second day.The masses were measured every three days.At different time points,tumors were excised for immunohistochemistry staining.RESULTS Tumor growth curves show that compared with the control groups,three experimental groups all inhibited tumor growth,but the combined groups have the slowest tumor growth.Compared with irradiated alone groups,Ki-67 Labeling Index（LI）expression decreased in the concurrent groups（12 f/24 d＋CCX,t=5.666,P=0.004;18 f/36 d＋CCX,t=2.572,P=0.042）.Bromodeoxyuridine（BrdUrd）LI expression decreased in the concurrent groups（12 f/24 d＋CCX,t=5.93,P=0.001;18 f/36 d＋CCX,t=5.43,P=0.006）.Epithelial Growth Factor Receptor（EGFR）expression decreased in the concurrent groups（12 f/24 d＋CCX,Z=-0.281,P=0.037;18 f/36 d＋CCX,Z=-2.048,P=0.031）.Caspase-3 expression score were higher in the concurrent groups than irradiated alone（12 f/24 d＋CCX,Z=-2.92,P=0.05;18 f/36 d＋CCX,Z=-2.739,P=0.006）.CONCLUSIONS Tumor repopulation of FaDu squamous cell carcinoma during fractionated radiotherapy was validated by histopathology.Celecoxib combined with radiotherapy can significantly inhibit tumor growth.Celecoxib can improve radiosensitivity during radiotherapy,it is worthy of further clinical research.