Establishment and characterization of a human gastric carcinoma cell line that is highly metastatic to lymph nodes

The actual mechanisms by which carcinoma cells metastasize to lymph nodes a re still unclear, and there is a need to establish in vivo experimental mod els suitable for the investigation of lymph node metastasis. For the purpos e, we established a highly lymph node-metastasizing line, designated AZL5G, derived from a human gastric cancer cell line, AZ521, which had low capaci ty for lymph node metastasis. AZL5G cells transplanted orthotopically in th e nude mouse stomach metastasize predominantly to the regional lymph nodes, showing little potential for hematogenous metastasis. AZL5G tumors develop ing in the stomach and regional lymph nodes showed poorly differentiated ad enocarcinoma with medullary growth, and their histologic appearance strongl y resembled that of parental AZ521. The growth activities in vitro of low-m etastatic AZ521 and high-metastatic AZL5G were almost the same, but the tum origenicity in vivo of AZL5G was significantly higher than that of AZ521. A ZL5G cells also showed clearly higher abilities of cell locomotion and adhe sion to type IV collagen and fibronectin in vitro as compared with AZ521 ce lls. Flow cytometric analysis demonstrated that the expression of integrin beta(1) subfamily except for alpha 6 integrin was generally increased in AZ L5G cells than in AZ521 cells. Especially, the expression of alpha(1), alph a nd alpha(2) integrins in AZL5G cells was clearly higher than in AZ521, wh ile alpha,beta(3), integrin, E-cadherin, ICAM-1 and CD44H were not expresse d by either cell line. The cell adhesion blocking assay showed that DGEA-co ntaining peptide, which is composed of a, integrin recognition sequence, si gnificantly reduced the adhesiveness of AZL5G cells to type IV collagen as well as to type I collagen and laminin. Furthermore, the administration of anti-alpha(2) integrin mAb or DGEA peptide in AZL5G-transplanted nude mice produced a significant reduction in the number of lymph node metastases. Th ese data suggest that the up-regulation of a, integrin expression by gastri c cancer cells may play a critical role in the process of lymph node metast asis through the increased adhesiveness to type IV collagen. In conclusion, we established a gastric cancer cell line, AZL5G, with a highly metastatic potential to lymph nodes. This well-characterized line and its in vivo exp erimental model should be useful for investigation of the mechanisms of lym ph node metastasis and for establishment of a new therapeutic approach for human gastric cancer.