阻断VEGF旁分泌通路抑制乳腺癌血管生成与肿瘤生长

以人乳腺癌细胞株MCF 7为研究对象 ,通过构建有义与反义血管内皮生长因子 (VEGF)基因表达质粒 ,并转染MCF 7细胞 ,建立了高与低水平表达VEGF的细胞克隆。稳定转染反义VEGF表达质粒的细胞产生和分泌VEGF的能力明显下降 ,尽管在体外培养条件下细胞的增殖速度与未经转染的对照相比不是减慢而是略有增快 ,但在体内的成瘤能力、生长速度和转移能力等却明显低于未经转染的对照细胞或稳定转染有义VEGF表达质粒高水平表达VEGF的细胞克隆。通过体内电穿孔技术介导反义VEGF12 1及可溶性VEGF受体sFlk 1表达质粒转移至荷瘤鼠肿瘤组织内 ,反义VEGF12 1及sFlk 1的表达能显著抑制肿瘤的生长。研究结果证实了VEGF旁分泌通路在诱导乳腺癌肿瘤血管生成、促进肿瘤生长和转移方面起重要作用 ,阻断VEGF旁分泌通路能有效抑制乳腺癌的生长

Inhibitation of Tumor Angiogenesis, Growth and Metastasis by Blocking VEGF Paracrine Pathway

Solid tumors require an adequate vascular supply to grow beyond a certain dimension. It is known that formation of new blood vessels in tumor is mediated by unbalanced expression of angiogenic factors and their inhibitors. Among the former, the vascular endothelial growth factor (VEGF) has been assumed prime candidacy as a major positive physiological effector. To investigate the role of VEGF in angiogenesis associated with development of breast cancer, a sense VEGF and an anti-sense VEGF expression plasmids were constructed, and then were introduced into a human breast carcinoma cell line, MCF-7, expressing middle level of endogenous VEGF. Anti-sense VEGF 121 transfected MCF-7 cells that expressed reduced constitutive levels of VEGF and showed the same growing potential as untransfected MCF-7 cells in vitro, but it showed longer latency, smaller tumor, slower growth and prolonged survival time compared to parental or sense VEGF 165 transfected MCF-7 cells in vivo. Moreover, the tumors derived from anti-sense VEGF 121 transfected MCF-7 cells characterized by minimal vascularization and extensive necrosis. Finally, mice with primary subcutaneous tumors treated with intratumoral administration of anti-sense VEGF, or the plasmid expressing extracellular domain of the Flk-1 VEGF receptor (sFlk-1) followed by electroporation, showed significant tumor suppression. These results suggest that VEGF plays a major angiogenic role in breast cancer and a strategy, which blocks the VEGF paracrine pathway, may provide a means to control tumor growth topically without the risk of systemic antiangiogenesis.