Analysis of human monoclonal antibody suppressing metastasis and the mechanism of metastasis.

本研究的目的是系统地研究细胞表面蛋白在调控细胞运动和血管生成中的可能作用，并进一步确定与恶性肿瘤相关的细胞表面分子。我们使用功能性人类单抗(MAb)解决了这些问题，单抗可以抑制细胞的运动。此外，我们还利用KM小鼠建立了人源性单抗。我们已经建立了11个抑制肺转移的单抗。其中有7种单抗能识别蛋白质，其余的单抗针对糖蛋白和糖脂等糖链。此前，我们建立了一种小鼠单抗MH8-11，它可以在体外抑制细胞运动和血管生成。序列分析表明，该表位与氨基肽酶N(APN)/分化簇13(CD13)几乎完全相同。转导B16-F1的APN具有潜在的肺转移能力。利用肺癌、结肠癌和胰腺癌的实际临床标本，我们发现APN的表达与血管生成有关，是预后不良的重要因素。目前，作为分子靶向治疗，我们建立了识别APN的人源性单抗。MT95-4对APN酶活性的抑制能力强于鼠源单抗MH8-11。利用肺转移潜能高的F1细胞株，我们证明了MT95-4单抗能有效地阻止F1细胞的肺转移。使用MT95-4，我们可能能够将各种癌症作为一种分子靶向治疗。

The aims of this study were to systematically investigate the possible involvement of proteins at the cell surface in controlling cell motility and angiogenesis, and further identify the cell surface molecules involved in malignant tumors. We addressed these issues using functional human monoclonal antibodies (MAbs), which inhibit cell motility. In addition, we established human monoclonal antibodies using KM mice. We have established 11 monoclonal antibodies which suppress lung metastasis. Among them, 7 kinds of monoclonal antibodies have recognized proteins and the others were directed to sugar chains like glycoproteins and glycolipids. Previously, we established a murine MAb MH8-11, which inhibits cell motility and in vitro angiogenesis. This epitope was a 165-kD protein and the sequencing analysis revealed that it was almost identical to aminopeptidase N (APN)/cluster of differentiation 13 (CD13). The APN transfected B16-F1 gained a potential ability of metastasis to the lung. Using the actual clinical specimens of lung cancer, colon cancer and pancreatic cancer, we found that the expression of APN had an association with angiogenesis, and was a significant factor of a poor prognosis. Currently, as the molecular targeting therapy, we established the human monoclonal antibodies recognizing APN. MT95-4 has a stronger ability suppressing APN enzyme activity than the mouse monoclonal antibody MH8-11. Using the F1 cell line with highly metastatic potential to the lung, we demonstrated that MT95-4 MAb efficiently prevented the pulmonary metastasis of F1. Using MT95-4 we might be able to treat the various kinds of cancers as a molecular targeting therapy.