Antitumor effect utilizing antiangiogenic activity by ribozyme

众所周知，肿瘤需要持续的血管生成来支持其生长。通过产生抗血管生成因子来抑制血管生成应该是一种可行的癌症基因治疗方法。同样，抑制血管生成因子对抑制肿瘤生长也有影响。血管内皮生长因子（Vascular endothelial growth factor， VEGF）是肿瘤血管生成的关键调控因子，许多研究表明，VEGF在许多人类肿瘤中上调。我们计划用核酶抑制血管内皮生长因子受体。然而，我们未能制造出能够分泌核酶来抑制VEGF受体的载体。相反，我们把注意力转向了RNA干扰。RNA干扰（RNAi）是转录后沉默基因表达的有力工具。将核酶靶向VEGF在肿瘤细胞中调控肿瘤血管生成的策略改为RNAi技术。我们研究了靶向血管内皮细胞vegf受体（VEGFR）基因的小干扰RNA （siRNA）双链沉默对血管内皮细胞血管生成活性的抑制作用，并在体内模型中评估了其对肿瘤进展的影响。我们优化了VEGFR-1的RNAi靶序列。血管内皮细胞转染VEGFR-1 siRNA可显著降低VEGFR-1的表达。进一步优化VEGFR-2的RANi靶序列，构建靶向VEGFR-2表达载体的shRNA。现在我们计划在体内模型中评估这种强大的效用。

It has been known that tumors require ongoing angiogenesis to support their growth. Inhibition of angiogenesis by production of antiangiogenic factors should be a viable approach for cancer gene therapy. Similarly, inhibition of angiogenic factor has an impact to suppress the tumor growth. Vascular endothelial growth factor (VEGF) is a key regulator of tumor angiogenesis and many studies have shown that VEGF is upregulated in many human tumors. We have planned to inhibit vascular VEGF receptors using ribozyme. However we have failed to produce the vector to secrete ribozyme to inhibit VEGF receptors. Instead of that, we have turned our attention to RNA interference. RNA interference (RNAi) is a powerful tool to silence gene expression post-transcriptionally. The strategy to regulate the tumor angiogenesis with the ribozyme targeted VEGF in tumor cell was changed to it with RNAi technique. We investigated the silencing effect of small interfering RNA (siRNA) duplexes targeting the gene VEGF-receptor (VEGFR) in vascular endothelial cell to inhibit its activity of angiogenesis and evaluated its effect against to the tumor progression in vivo model. We optimized the RNAi target sequence of VEGFR-1. Trasfection of VEGFR-1 siRNA to vascular endothelial cell specially reduced VEGFR-1 expression. Further, the RANi target sequence to VEGFR-2 was optimized and the shRNA targeted to VEGFR-2 expression vector was constructed. Now we plan to evaluate this powerful utility in in vivo model.