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癌症基因治疗的一个可行的方法。同样，抑制血管生成因子也有抑制肿瘤生长的作用。血管内皮生长因子(VEGF)是肿瘤血管生成的关键调节因子，许多研究表明，在许多人类肿瘤中，VEGF表达上调。我们已经计划使用核酶来抑制血管内皮细胞生长因子受体。然而，我们未能生产出分泌核酶来抑制血管内皮生长因子受体的载体。相反，我们将注意力转向了RNA干扰。RNA干扰(RNAi)是转录后沉默基因表达的有力工具。利用RNAi技术改变了以肿瘤细胞中的血管内皮生长因子为靶点的核酶调控肿瘤血管生成的策略。我们研究了靶向血管内皮细胞血管内皮生长因子受体(VEGFR)基因的小干扰RNA(SiRNA)双链抑制血管生成活性的作用，并评价了其对体内肿瘤进展的抑制作用。我们对VEGFR-1的RNAi靶序列进行了优化。血管内皮细胞转导VEGFR-1 siRNA可特异性降低VEGFR-1的表达。进一步优化了针对VEGFR-2的RANI靶序列，构建了针对VEGFR-2的shRNA表达载体。现在我们计划在活体模型中评估这一强大的实用价值。

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.