以血管內皮生長因子受器競爭物抑制血管新生與B16/F10腫瘤生長之活體研究

Abstract

血管新生成是腫瘤發育時的一個重要階段，此外血管新生也參與腫瘤由良性轉為惡性的過程。血管內皮細胞生長因子 （Vascular endothelial growth factor, VEGF）是促進內皮細胞生長與血管新生的必要因子，在先前的實驗中，本實驗室建構了一嵌合蛋白RBDV-Ig (Receptor binding domain of VEGF-Immuno- glibin)：是以人類血管內皮細胞生長因子(VEGF)中第1至108個胺基酸序列做為指標區域 (targeting domain)，其具有與受器，血管內皮細胞生長因子受器 (VEGF Receptor)，結合的能力；加上人類免疫球蛋白G1 (Immunoglobin G1) 的Fc 片段做為作用區域，以延長嵌合蛋白的半衰期。RBDV-Ig已被證明可於細胞培養模式中藉由專一性地與人類臍帶靜脈內皮細胞 (human umbilical vein endothelial cells, HUVECs) 表面的血管內皮細胞生長因子受器結合而阻斷血管內皮生長因子的訊息傳導途徑，達到抑制人類臍帶靜脈內皮細胞增生與形成管狀結構。本研究欲探討於小鼠模式中，嵌合蛋白RBDV-Ig是否可藉由抑制血管新生達到抑制腫瘤發展的目的。人類血管內皮細胞生長因子之受器結合區域 (Human VEGF receptor binding domain, hRBDV) 與小鼠血管內皮細胞生長因子之受器結合區域 (Mouse VEGF receptor binding domain, mRBDV) 有92%相似度，顯示RBDV-Ig有可能可與小鼠血管內皮細胞生長因子結合，且細胞實驗證明RBDV-Ig可與已證實有表現小鼠血管內皮細胞生長因子受器2 (mVEGFR2) 的MS1細胞結合。此外，RBDV-Ig可抑制SVEC4-10內皮細胞的增生。在C57/B6小黑鼠活體實驗方面，皮下注射RBDV-Ig與靜脈注射RBDV-Ig皆可顯著抑制B16/F10 腫瘤生長。以上結果顯示，RBDV-Ig可能可藉由抑制血管新生而抑制腫瘤生長，是為一種有潛力的癌症治療用藥。

Angiogenesis is not just an important stage in tumor growth but also involved in transforming a tumor from a benignancy to a malignant stage. Vascular endothelial growth factor (VEGF) is an essential factor in promoting endothelial cell growth and angiogenesis. In our previous experiments, we created a novel fusion protein, RBDV-Ig, which has a targeting domain, containing the amino acid sequences of VEGF from 1 to 108 with the binding activity to the human VEGF receptor, and an effector domain with Fc region of a human IgG1, used to increase a half-life of the fusion protein. RBDV-Ig has proven to inhibit tube-formation and proliferation through blocking the VEGF signal pathway by targeting the VEGF receptor on human umbilical vein endothelial cells (HUVECs) in vitro. Whether the RBDV-Ig chimeric protein can suppress tumor progression in vivo by anti-angiogenesis effect in the mouse model was verified in this study. The human VEGF receptor binding domain, RBDV is 92.7% similar to the mouse VEGF binding domain suggesting that the RBDV-Ig may bind to mouse VEGF receptors and later it was exactly proven to bind mouse VEGF receptor 2 (VEGFR2). It was also shown to bind to surface of mouse cells such as MS1 which have been proven with the VEGFR2 expression. Moreover, RBDV-Ig inhibits the proliferation of mouse SVEC4-10 endothelial cells in a dose-dependent way, but not of B16/F10. The results revealed that the tumor growths of B16/F10 tumors in C57/B6 mice were dramatically suppressed by subcutaneously injected RBDV-Ig. Tumor therapy with i.v. injection of RBDV-Ig also showed a similar result. Based on the results above, RBDV-Ig was shown to have the potent ability to inhibit tumor progression through suppression of angiogenesis and can be as a potential therapeutic drug in cancer therapy.