Inhibition of tumor angiogenesis through chondromodulin-I gene transfer

在我们的第一项研究中，我们研究了将软骨调节蛋白-I基因插入癌组织中是否可以通过阻止肿瘤血管生成来抑制肿瘤生长。Chondoromodulin-I被鉴定为一种血管生成抑制剂，来源于胎儿骨骺软骨提取物，该软骨通常不含毛细血管网络。目前，虽然在体外转染后检测到了软骨调节蛋白-I的蛋白表达，但用几种载体进行软骨调节蛋白-I基因转染后，尤其是体内转染后，效率并不高。因此，抑制肿瘤生长和降低微血管密度不显著。在第二项研究中，我们研究了雷帕霉素（mTOR抑制剂）对包括癌细胞在内的多种细胞系增殖活性和血管生成相关分子如血管内皮生长因子（VEGF）家族、血管生成素家族表达的影响。还在施用雷帕霉素后在体内评价肿瘤生长。在体外实验中，即使是相对低剂量的雷帕霉素处理后，VEGF-A mRNA和蛋白表达水平也显著降低。此外，VEGF-C的表达水平，这是一个强的淋巴管生成的启动子，也被发现下调。在体内，肿瘤生长被显著抑制。这些结果表明，雷帕霉素不仅可以抑制血管生成，而且淋巴管生成。基于这些结果，我们现在正在研究雷帕霉素是否可以通过抑制癌症淋巴管生成来预防淋巴结转移。

In our first study, we examined whether insertion of chondoromodulin-I gene into the cancer tissue could inhibit tumor growth through the prevention of tumor angiogenesis. Chondoromodulin-I was identified as an angiogenesis inhibitor derived from extracts of fetal epiphyseal cartilage, which is normally devoided of capillary network. At present, although chondoromodulin-I protein was detected in vitro after transfection, the efficiency was not high after chondormodulin-I gene transfer with several vectors, especially in vivo. Therefore, inhibition of tumor growth and reduction of microvessel density were not significant. We are now developing a new vector to provide for efficient gene transfer.In our second study, we investigated the effect of rapamycin (inhibitor of mammalian target of rapamycin (mTOR)) on the proliferation activity of several cell lines including cancer cells and the expression of angiogenesis-related molecules such as vascular endothelial growth factor (VEGF) family, angiopoietin family. Tumor growth was also evaluated in vivo after administration of rapamycin. In vitro, the levels of VEGF-A mRNA and protein expressions were significantly decreased after treatment of rapamycin with even relatively low dose. In addition, the expression level of VEGF-C, which is a strong promoter of lymphangiogenesis, was also found to be down-regulated. In vivo, tumor growth was significantly inhibited. These results suggest that rapamycin could inhibit not only angiogenesis but also lymphangiogenesis. Based on these results, we are now investigating whether rapamycin could prevent lymph node metastasis by inhibiting cancer lymphangiogenesis.