Morphological study of the interaction between M21 melanoma and lymphatic endothelium

In order to study the interaction between melanoma and lymphatic endothelial cells (LECs) and to investigate the mechanism of lymphatic metastasis, M21 melanoma cells were seeded on the confluent LECs monolayer and the alterations of both cells were observed. The results showed that tumor cells could both adhere by pseudopodia to LECs at the site near the intercellular junction and on the apical surface. The adhesion of the melanoma cells induced the endothelial junction dissolution and endothelial retraction, which allowed the passage of the tumor cells through the opened gap and attached to the subendothelial matrix, then the tumor cells invaded and migrated under the LECs monolayer. These findings suggest that tumor cells could metastasize through the lymphatic vessel by destroying intercellular junctions or the LECs directly.