IL-24联合靶向减毒沙门菌载体SL7207／pBud-V P3对胃癌细胞的生长抑制作用

目的：探讨白细胞介素（IL）‐24联合靶向减毒沙门菌载体SL7207／pBud‐VP3对胃癌细胞生长的抑制作用及机制。方法构建 pBud‐VP3‐IL‐24真核双表达质粒，利用高压电穿孔法将pBud‐Vp3‐IL‐24质粒导入减毒沙门菌SL7207株中，构成SL7207／pBud‐VP3‐IL‐24菌株。建立小鼠胃癌移植瘤模型，将模型随机分为生理盐水对照组、SL7207／pBud组、SL7207／pBud‐VP3组及SL7207／pBud‐VP3‐IL‐24组，菌株口服饲喂荷瘤小鼠，测量肿瘤体积并计算抑瘤率。采用蛋白质印迹法检测肿瘤组织中IL‐24的表达；采用实时荧光定量‐PCR（RT‐PCR）检测干扰素‐γ（IFN‐γ）、IL‐6及肿瘤坏死因子‐α（TNF‐α）水平；采用免疫组织化学法测定半胱氨酸天冬氨酸蛋白酶‐3（Caspase‐3）及血管内皮生长因子（VEGF）的表达。结果成功构建基于IL‐24的减毒沙门菌载体系统SL7207／pBud‐VP3‐IL‐24；治疗14 d后，胃癌组织可检测到IL‐24蛋白的表达；治疗28 d后，SL7207／pBud‐VP3‐IL‐24组与其他组比较，肿瘤体积缩小并能够明显抑制肿瘤生长，差异有统计学意义（ P＜0．05）。RT‐PCR及免疫组织化学显示，IL‐24联合SL7207／pBud‐VP3能够明显增加免疫因子IFN‐γ、IL‐6及TNF‐α的表达水平（P＜0．05），上调Caspase‐3及下调VEGF的表达（P＜0．05）。结论 IL‐24联合SL7207／pBud‐VP3可以协同发挥对胃癌细胞的生长抑制作用，其作用机制与肿瘤凋亡促进、肿瘤血管抑制、免疫调节等有关。

Inhibiting effect of IL-24 combined with targeting attenuated Salmonella vector SL 7207/pBud-Vp3 on growth of gastric cancer cells

Objective To investigate the inhibiting effect of interleukin (IL)‐24 combined with targeted attenuated Salmonella typhimurium vector SL7207/pBud‐VP3 on the growth of gastric cancer cells .Methods The co‐expression eukaryotic expression plasmid pBud‐VP3‐IL‐24 was constructed .The plasmid pBud‐VP3‐IL‐24 was transformed into attenuated Salmonella typhimurium SL7207 by using the high voltage electroporation for constructing the SL 7207/pBud‐VP3‐IL‐24 strain .The mouse gastric cancer transplantation tumor model was established and randomly divided into the normal saline control group ,SL7207/pBud group , SL7207/pBud‐VP3 group and SL7207/pBud‐VP3‐IL‐24 group .The tumor‐bearing mice were fed by oral administration of bacterial strain .The tumor volume was measured and the tumor inhibition rate was calculated .The expression of IL‐24 was detected by Western blotting .The levels of IFN‐γ,IL‐6 and TNF‐αin tumor tissue were detected by using RT‐PCR .The expression of Caspase‐3 and VEGF were detected by using immunohistochemistry .Results The plasmids attenuated Salmonella typhimurium vector carrying the gene IL‐24 was successfully constructed .The IL‐24 protein expression was detected in gastric cancer tissue after 14 d treatment .The tumor volume after 28 d treatment in the SL7207/pBud‐VP3‐IL‐24 group was reduced compared with the other groups ,moreover the tumor growth was significantly inhibited ,and the differences were statistically significant (P<0 .05) .RT‐PCR and immunohistochemistry results showed that IL‐24 combined with SL7207/bBud‐VP3 could significantly increase the expression levels of immune factor IL‐6 ,IFN‐γ and TNF‐αin tumor tissue ,.in addition ,up‐regulated the expression of Caspase‐3 and down‐regulated the VEGF expression(P<0 .05) .Conclu‐sion IL‐24 combined with SL7207/pBud‐VP3 can synergically play the inhibitory effect on the growth of gastric cancer cells ,its mecha‐nism is related with the tumor apoptosis promotion ,tumor vessel inhibition and immune regulation .