Investigation of the Mechanism of Angiogenin-Mediated Cancer Cell Proliferation and Tumor Angiogenesis, and Its Application for Cancer Treatment

本研究通过靶向血管生成素的RNAi技术建立口腔癌的抗肿瘤模型，旨在阐明血管生成素介导的肿瘤细胞增殖和肿瘤血管生成的机制，为其在肿瘤治疗中的应用奠定基础。因此，筛选出高水平分泌血管生成素和血管内皮生长因子的HSC-2细胞和低水平分泌血管生成素和高水平血管内皮生长因子的SCCKN细胞，并构建了血管生成素RNAi载体。RNAi下调血管生成素的表达可抑制体外培养的HSC-2细胞的增殖，并导致HSC-2细胞45S核糖体RNA转录、核糖体生物合成和Akt(Ser473)磷酸化水平降低。此外，下调HSC-2细胞中血管生成素的表达可显著减少裸鼠的肿瘤体积，尽管它分泌高水平的血管生成素。这些结果表明，血管生成素不仅在口腔癌的肿瘤血管生成中起关键作用，而且在口腔癌的细胞增殖中也起关键作用。此外，血管生成素可能是血管内皮生长因子在肿瘤血管生成中所必需的。

In this study, we made an antitumor model of oral cancer by RNAi technology targeting angiogenin, and aimed to elucidate the mechanism of angiogenin-mediated cancer cell proliferation and tumor angiogenesis in order to apply it for cancer treatment.Secreted levels of angiogenin and VEGF in various oral cancer cell lines were measured by ELISA. As a result, HSC-2 cell that secreted high levels of angiogenin and VEGF, and SCCKN cell that secreted low level of angiogenin and high level of VEGF were selected, and transfected with angiogenin RNAi construct. Down-regulation of angiogenin expression by RNAi decreased proliferation in both of the cells in vitro, and resulted in a decrease in 45S ribosomal RNA transcription, ribosome biogenesis and phosphorylation of Akt (Ser473) in HSC-2 cell. Besides, knocking down angiogenin expression in HSC-2 cell strongly decreased tumor volume in athymic mice although it secreted high level of VEGF.These results suggested that angiogenin plays a key role in not only tumor angiogenesis but also cell proliferation in oral cancer. Moreover, angiogenin may be necessary for tumor angiogenesis by VEGF.