Angiogenesis and Tumor Growth

肿瘤的存活、生长和扩散依赖于由新血管形成、现有血管的共选择和干细胞分化为内皮细胞所确保的充足的血液供应。 因此，血管生成抑制剂可能代表治疗癌症的新工具。 我们观察到EBV永生化细胞的上清液通常含有内皮细胞增殖的抑制剂。 从淋巴母细胞VDS-O细胞系的上清液中，我们纯化了内皮细胞抑制剂，并将其鉴定为钙网蛋白的NH 2-末端片段的混合物。 重组纯化的钙网蛋白的NH 2-末端片段（氨基酸1-180）抑制内皮细胞的增殖，但不抑制其他谱系细胞的增殖，并抑制体内血管生成。 我们将其命名为钙网蛋白vasostatin的NH 2-末端结构域。 当接种到无胸腺小鼠，vasostatin减少伯基特淋巴瘤，结肠癌，乳腺癌，黑色素瘤，横纹肌肉瘤，肺腺癌和Wilms肿瘤的生长。 全长钙网蛋白、缺乏NH 2末端1-120个氨基酸的钙网蛋白和包含氨基酸120-180的内部钙网蛋白片段在体内抑制内皮细胞增殖、血管生成和肿瘤生长。 这些结果表明，抗血管生成和抗肿瘤活性的vasostatin驻留在一个域，是从全长钙网蛋白分子和本地化的NH 2结构域内的内部61个氨基酸的片段。 因此，我们已经确定钙网蛋白和血管抑素作为新的血管生成抑制剂，抑制肿瘤生长的临床前肿瘤模型。

Survival, growth and spread of tumors depend upon an adequate blood supply ensured by neovascularization, cooption of existing vessels and stem cell differentiation into endothelial cells. Thus, inhibitors of angiogenesis may represent novel tools for the treatment of cancer. We observed that supernatants of EBV-immortalized cell generally contain inhibitors of endothelial cells proliferation. From supernatants of the lymphoblastic VDS-O cell line we purified an endothelial cell inhibitor, and identified it as a mixture of NH2-terminal fragments of calreticulin. The recombinant purified NH2-terminal fragments of calreticulin (amino acids 1-180) inhibited the proliferation of endothelial cells but not the proliferation of cells of other lineages, and suppressed angiogenesis in vivo. We have named this NH2-terminal domain of calreticulin vasostatin. When inoculated into athymic mice, vasostatin reduced growth of Burkitt lymphoma, colon carcinoma, breast adenocarcinoma, melanoma, rhabdomyosarcoma, lung adenocarcinoma and Wilms tumors. Full-length calreticulin, calreticulin lacking the NH2 terminal 1-120 amino acids, and an internal calreticulin fragment encompassing amino acids 120-180 inhibited endothelial cell proliferation, angiogenesis, and tumor growth in vivo comparably to vasostatin. These results suggest that the antiangiogenic and antitumor activities of vasostatin reside in a domain that is accessible from the full-length calreticulin molecule and localized to an internal 61 amino acids fragment within the NH2 domain of calreticulin. Thus, we have identified calreticulin and vasostatin as novel angiogenesis inhibitors that suppress tumor growth in preclinical tumor models.