Schmitz V, Vilanueva H, Raskopf E, Hilbert T, Barajas M, Dzienisowicz C, Gorschlüter M, Strehl J, Rabe C, Sauerbruch T, Prieto J, Caselmann W H, Qian C
Department of Internal Medicine I, University Hospital, Bonn, Germany.
Gene Ther. 2006 Aug;13(16):1198-205. doi: 10.1038/sj.gt.3302772. Epub 2006 Apr 13.
Inhibition of vascular endothelial growth factor (VEGF) by gene transfer techniques was effectively applied to control experimental tumor growth, whereas effects on systemic VEGF levels had not been investigated. Therefore, we evaluated the effect of VEGF inhibition by adenoviral-mediated gene delivery of a dominant-negative soluble fragment of FLK-1 (sFlk-1) on systemic VEGF levels, organ-specific VEGF-RNA expression and antitumor efficacy in a murine colorectal cancer (CRC) tumor model. Vector function of AdsFlk-1 was shown by Western blot analysis and transgene expression was documented over a time period of 42 days in the serum of treated mice. Although cell supernatant of CT26 cells contained considerable levels of VEGF, systemic VEGF levels in the serum of tumor-bearing mice remained unaffected. Interestingly, mice that were systemically treated with AdsFlk-1 showed a strong upraise of circulating VEGF, whereas VEGF remained at background levels in the control. Vascular endothelial growth factor was increased not only in tumor bearing but also in healthy, tumor-free mice. Vascular endothelial growth factor determination in liver tissue homogenates showed a 16.5-fold upraise in AdsFlk-1-treated animals as compared to the AdLacZ control. Consecutively, systemic small interfering RNA injection targeted against VEGF reverted elevated VEGF levels almost back to normal levels. In spite of elevated VEGF levels, AdsFlk-1 administration showed significant antitumor effects in a subcutaneous metastatic CRC tumor model. There was no significant correlation between antitumour treatment response and VEGF levels in this model. Collectively, we conclude that the systemic administration of AdsFlk-1 had significant inhibitory effects on metastatic CRC tumor growth in spite of elevated systemic VEGF levels and that VEGF serum concentrations did not correlate to tumor burden and antitumor treatment response in this model.
通过基因转移技术抑制血管内皮生长因子（VEGF）已有效地应用于控制实验性肿瘤生长，而对全身VEGF水平的影响尚未得到研究。因此，我们在小鼠结直肠癌（CRC）肿瘤模型中评估了腺病毒介导的FLK-1显性负性可溶性片段（sFlk-1）基因递送对全身VEGF水平、器官特异性VEGF-RNA表达和抗肿瘤疗效的影响。通过蛋白质免疫印迹分析显示了AdsFlk-1的载体功能，并在处理小鼠的血清中记录了42天时间段内的转基因表达。尽管CT26细胞的细胞上清液含有相当水平的VEGF，但荷瘤小鼠血清中的全身VEGF水平未受影响。有趣的是，经AdsFlk-1全身治疗的小鼠循环VEGF显著升高，而对照组的VEGF保持在背景水平。血管内皮生长因子不仅在荷瘤小鼠中增加，在健康的无瘤小鼠中也增加。肝组织匀浆中的血管内皮生长因子测定显示，与AdLacZ对照组相比，经AdsFlk-1处理的动物中VEGF升高了16.5倍。随后，针对VEGF的全身小干扰RNA注射几乎将升高的VEGF水平恢复到正常水平。尽管VEGF水平升高，但在皮下转移性CRC肿瘤模型中，给予AdsFlk-1显示出显著的抗肿瘤作用。在该模型中，抗肿瘤治疗反应与VEGF水平之间无显著相关性。总体而言，我们得出结论，尽管全身VEGF水平升高，但AdsFlk-1的全身给药对转移性CRC肿瘤生长具有显著抑制作用，并且在该模型中VEGF血清浓度与肿瘤负荷和抗肿瘤治疗反应无关。
