COX-2抑制剂联合舒尼替尼增强对荷瘤小鼠肾癌抑制作用的机制

COX-2 inhibitor enhances the activity of sunitinib in renal cell carcinoma-bearing mice and its mechanism

目的通过COX-2抑制剂与舒尼替尼联合用药,观察其对荷RenCa肾癌BALB/c小鼠移植瘤的抑制作用,以及对小鼠外周血、脾脏、淋巴结的骨髓源性抑制细胞(myeloid-derived suppressor cell,MDSC)与调节性T细胞(regulatory T cell,Treg)的影响。方法建立BALB/c小鼠RenCa肾癌皮下移植瘤模型。模型动物分为4组,每组10只,分别为舒尼替尼治疗组、COX-2抑制剂(塞来昔布)治疗组、舒尼替尼+COX-2抑制剂治疗组和空白对照组。各组按时给药并绘制肿瘤生长曲线;流式细胞术检测小鼠外周血、脾脏中Treg、MDSC数目的变化;流式细胞术分选MDSC,提取蛋白质,Western blot检测STAT-3水平。结果联合用药组相较于对照组,脾脏MDSC数目明显降低(1.22%±0.15%vs.9.34%±0.58%,P<0.01),外周血MDSC数目明显降低(12.7%±0.85%vs.23.0%±1.68%,P<0.01),脾脏Treg明显降低(11.3%±1.69%vs.22.4%±2.31%,P<0.01),外周血Treg明显降低(3.30%±0.64%vs.11.9%±1.53%,P<0.01)。经流式细胞术分选后的脾脏MDSC中,联合用药组较单用药组STAT-3水平明显下降(P<0.01)。结论 COX-2抑制剂与舒尼替尼联合用药对肾透明细胞癌的抗肿瘤作用优于任何单独用药,其机制可能是通过减少免疫抑制细胞,调节机体肿瘤免疫环境,从而增强分子靶向药物的抗肿瘤效果。

Objective To explored the potential benefits of COX-2 inhibitor（celecoxib）in combination with sunitinib and explain the mechanism about the suppression of myeloid derived suppressor cell（MDSC）and regulatory T cell（Treg）in peripheral blood,spleen,lymph node of RenCa tumor-bearing BALB/c mice. Methods BALB/c mice transplanted of RenCa cells were divided into4 groups（n=10）and then treated with sunitinib,COX-2 inhibitor（celecoxib）,combined medication（celecoxib＋sunitinib）and PBS by gavage.Tumor growth curve and the mice survival were observed.The changes of Treg and MDSC in the peripheral blood and spleen were determined by flow cytometry.MDSC cells were selected by flow cytometry and its protein was extracted for STAT-3 analysis by Western blot. Results Combined medication can reduce MDSC in spleen（1.22% ±0.15%vs.9.34%±0.58%,P 0.01）and peripheral blood（12.7%±0.85% vs.23.0%±1.68%,P0.01）.Meanwhile,combined medication can reduce Treg in spleen（11.3%±1.69%vs.22.4%±2.31%,P 0.01）and peripheral blood（3.30%±0.64% vs.11.9%±1.53%,P0.01）.The expression of STAT3 in MDSC selected from the spleen by flow cytometry was also downregulated in combined medication group compared with celecoxib and sunitinib groups.Conclusions COX-2 inhibitor in combination with sunitinib has more effectivethan sunitinib or COX-2inhibitor alone on renal cell carcinoma.Its mechanism might be that COX-2 inhibitor and sunitinib combination therapy can enhance anti-tumor effect by reducing immunosuppressive cells and regulating tumor microenvironment.