Tumor progression largely depends on blood supply and neovessel formation, and angiogenesis is emerging as a promising target for cancer therapy. Vascular endothelial growth factor (VEGF), a major proangiogenic molecule, stimulates angiogenesis via promoting endothelial proliferation, urvival and migration. VEGF has been found to be up-regulated in various types of tumors and to be associated with tumor progression and poor prognosis. Inhibition of VEGF or its signaling pathway has been shown to suppress tumor angiogenesis and tumor growth. In the present study, we tested the antiangiogenic and antitumor effects of soluble VEGF receptor-1 [soluble Flt (sFlt)-1] on the growth of follicular thyroid carcinoma (FTC). We constructed a 293 embryonic kidney cell line (293-Flt1-3d) that expresses sFlt-1, which is composed of the first three extracellular domains of Flt-1. The 293-Flt1-3d cells inhibited the in vitro growth of human umbilical vein endothelial cells in a paracrine manner. The in vivo antitumor and antiangiogenic activities of the 293-Flt1-3d cells were tested. When 293-Flt1-3d cells were inoculated at a site remote to the FTC-133 tumor transplant, the growth of FTC-133 tumors were inhibited by 70.37%, as compared with the control treatment with 293 cells expressing control gene LacZ. Immunohistochemical analysis of microvessel densities in treated tumors demonstrated that 293-Flt1-3d cells robustly suppressed intratumoral angiogenesis. Our data suggest that a mammalian cell-mediated approach could effectively deliver sFlt-1 gene therapy and inhibit tumor angiogenesis and tumor growth.

目的 研究对前甲状腺激素原基因进行定点突变，并转染体细胞产生成熟甲状旁腺激素。方法 采用聚合酶链反应（PCR）定点突变技术，自组织基因组基因中扩增前甲状旁腺激素原的cDNA，并将野生型甲状旁腺激素编码第28位的密码子GTT突变为AGA，使N端28-31氨基酸变为Arg-Lys-Lys-Arg，成为furin酶的酶切位点；将获得的突变表达载体pcDNA3.1/mPTH通过脂质体法转染体外培养的293细胞，用放射免疫法测定表达水平。结果 成功地获得突变型甲状旁腺激素原cDNA，293细胞转染突变表达载体后，每日培养液中甲状旁腺激素含量达28.34～52.64pg/2.0×106细胞，远高于空载体转染的细胞培养液。结论 利用PCR技术可获得突变型甲状旁腺激素原的cDNA，突变表达载体pcDNA3.1/mPTH能成功转染体细胞并产生甲状旁腺激素。