反义血管内皮生长因子原位表达抑制白血病细胞系K562在裸鼠体内生长并诱导其凋亡

Intratumoral Injection of Antisense VEGF Plasmid Suppresses K562 Cells Growth in Nude Mice and Increases Apoptosis of Leukemia Cells

目的观察反义血管内皮生长因子(anti-VEGF)原位表达对白血病细胞系K562在裸鼠体内生长的影响。方法选用白血病细胞系K562裸鼠体内接种成瘤后,肿瘤内注射重组反义VEGF真核表达质粒及空载体和PBS,检测反义VEGF体内转染情况及其对肿瘤生长的影响;免疫组化法比较实验组和对照组移植瘤微血管密度(MVD)及白血病细胞的凋亡情况。结果注射反义VEGF表达质粒能抑制肿瘤的生长,使肿瘤的MVD显著降低(25.6±5.77VS41±3.8,P<0.05),并且使肿瘤细胞凋亡增加。结论肿瘤内注射反义VEGF重组表达质粒在体内能有效转染肿瘤及其周围组织,反义VEGF体内的表达能抑制白血病细胞肿瘤的生长,降低肿瘤内MVD,促进白血病细胞的凋亡。反义VEGF基因治疗策略提供了一种新的白血病辅助治疗方案。

Objective To investigate the effect of antisense vascular endothelial growth factor （VEGF）121 cDNA transfection in vivo on the growth of leukemia K562 cells in nude mice. Methods A plasmid encoding antisense VEGF121 cDNA was delivered directly into a growing tumor （K562 chronic myeloid leukemia） established at 5 mm of average diameter. The mice received three injections of the pIRES2 - EGFP plasmid of 50 mg given at 5 - day interval. The control groups received either PBS or the pIRES2 - EGFP plasmid alone. Tumor volumes were determined. The microvessel density （MVD） in tumor mass was counted by anti - CD31 immunohistochemistry staining, and the level of apoptotic cells was investigated by TUNEL staining. Results Direct, intratumoral injection of the plasmid induced transfection and expression of antisense VEGF in tumor and surrounding normal cells. Antisense VEGF transfection in vivo inhibited tumor growth. The microvessel density was significantly decreased （25.6±5.77 vs 41±3.8, P 〈 0.05）. TUNEL staining demonstrated an increase of cell apoptosis in the tumors from antisense - VEGF vector compared to those from control vector. Conclusions Direct intratomural injection of the plasmid carrying an antisense VEGF121 cDNA can reduce tumor growth in transplanted nude mice, decrease tumor MVD, and increase tumor cell apoptosis.