STAT3基因沉默对人胰腺癌SW1990细胞的裸鼠移植瘤生长的影响

Effect of STAT3 gene silencing on xenografts in human pancreatic cancer SW1990 in nude mice

目的 观察信号转导与转录激活因子3（STAT3）基因表达沉默后对人胰腺癌SW1990细胞的裸鼠移植瘤生长的影响,探讨其机制.方法 构建靶向STAT3短发卡RNA（shRNA）表达载体,稳定转染胰腺癌SW1990细胞（SW1990-RNAi组）,以转染阴性对照shRNA表达载体细胞（SW1990-Con组）及亲本SW1990细胞（SW1990组）作为对照.应用蛋白质印迹法检测各组细胞STAT3、血管内皮生长因子（VEGF）、基质金属蛋白酶2（MMP-2）蛋白的表达.建立各组细胞的裸鼠皮下移植瘤模型,观察移植瘤的生长,应用免疫组化法检测移植瘤的CD34表达,计算肿瘤的微血管密度（MVD）.结果 SW1990组、SW1990-Con组、SW1990-RNAi组细胞的STAT3蛋白表达量分别为84.69±9.31、82.00±7.76、7.93±1.24,VEGF蛋白表达量分别为82.94±8.97、80.86±10.28、39.04±6.23,MMP-2蛋白表达量分别为40.88±5.09、38.26±5.71、12.54±2.15,SW1990-RNAi组均显著低于其他两组（P值均＜0.05）,而SW1990-Con组与SW1990组细胞的3种蛋白表达量差异均无统计学意义.SW1990组、SW1990-Con组、SW1990-RNAi组裸鼠移植瘤的重量分别为（2.2±0.4）、（2.2±0.3）、（0.5±0.3）g,瘤组织的MVD分别为每高倍视野（20.35±2.41）、（18.79±1.94）、（9.62±1.06）个,SW1990-RNAi组均显著低于其他两组（P值＜0.05或＜0.01）,而SW1990组与SW1990-Con组间的差异均无统计学意义.结论 STAT3基因表达被抑制后SW1990细胞的裸鼠移植瘤生长减缓,其机制可能是通过下调VEGF及MMP-2的表达、抑制肿瘤血管形成所致.

Objective To investigate the effect and mechanism of STAT3 gene silencing on the growth of xenografts in human pancreatic cancer SW1990 cells in nude mice. Methods The expression vector inserted with shRNA targeting at STAT3 gene was constructed and was stably transfected into SW1990 cells （SW1990-RNAi group）. SW1990 cells transfected with negative control shRNA expression vector （SW1990- Con group） and parent SW1990 （SW1990 group） were used as controls. STAT3, VEGF, MMP-2 protein expressions in these groups were determined by using Western blot. The subcutaneous xenografts models were established in nude mice, and the growth of xenografts was observed, CD34 expressions were determined by immunohistochemistry and MVD was measured. Results The expression of STAT3 protein was 84.69 ± 9.31, 82.00 ±7.76, 7.93 ± 1.24, repectively, in SW1990 group, SW1990-Con group, SW1990-RNAi group, and the expression of VEGF protein was 82.94 ±8.97, 80.86 ± 10.28, 39.04 ± 6.23, respectively, and the expression of MMP-2 protein was 40.88 ± 5.09, 38.26 -± 5.71, 12.54 ,± 2.15, respectively. The expression in SWt990- RNAi group was significantly lower than those in other 2 groups （ P 〈 0.05 ）, while the expression of all three proteins between SW1990-Con group and SW1990 group was not significantly different. The weight of the xenografts in SW1990 group, SW1990-Con group, SW1990-RNAi group was （ 2.2 ± 0.4）, （ 2.2 ± 0.3 ）, （0.5± 0.3 ） g, respectively; the MVD of the xenografts was （ 20.35 ± 2.41 ）, （ 18.79 ± 1.94 ）, （ 9.62 ± 1.06） per high power field, respectively, and the number in SW1990-RNAi group was significantly lower than those in other 2 groups （P 〈 0.05 or P 〈 0.01 ）, while the difference between SW1990-Con group and SW1990 group were not significant. Conclusions Inhibition of STAT3 gene expression can significantly slow the growth of SW1990 xenografts in nude mice, and the mechanism may be related with down-regnlation of VEGF and MMP-2 expression and inhibition of the angiogenesis of pancreatic cancer.