A NOVEL IN-VITRO ASSAY SYSTEM FOR TRANSENDOTHELIAL TUMOR-CELL INVASION - SIGNIFICANCE OF E-SELECTIN AND ALPHA(3) INTEGRIN IN THE TRANSENDOTHELIAL INVASION BY HT1080 FIBROSARCOMA CELLS

The interaction of tumor cells with endothelial cells is a key event in tumor metastasis. We established an in vitro invasion assay system, in which the invasion of tumor cells after interaction with endothelial cells can be examined. Two chamber culture wells separated by porous membrane were used. Human umbilical vein endothelial cells (HUVEC) were placed on porous membranes coated with matrix components. The invasion by HT1080 fibrosarcoma cells was determined in this system by counting the number of cells that moved through the membranes from upper to lower chambers. HUVEC cells did not migrate through the membranes as judged by the staining with UEA-I. Observation by scanning electron microscopy revealed that HT1080 cells bound to HUVEC surfaces and migrated underneath the HUVEC monolayer. Effects of antibodies specific for cell surface adhesion molecules on the migration of HT1080 cells were examined. Invasion of uncoated membranes and membranes coated with HUVEC cells was compared. Antibody against E-selectin significantly suppressed an increase of HT1080 cell invasion of HUVEC monolayers stimulated by IL-1 beta or TNF alpha. Antibody against integrin alpha(3) subunit remarkably inhibited the invasion of HUVEC cell-coated membranes, suggesting that integrins with the alpha(3) subunit may play an important role in the transendothelial invasion by HT1080 cells.