A new endothelial molecule involved in melanoma cell binding to human dermal microvascular endothelial cells

Background: We have previously demonstrated that phorbol myristate acetate(PMA)-induced increases in melanoma cell binding to endothelial cells derived from human dermis (HDMEC) are not mediated via known cell adhesion molecules and may be affected through microvessel-specific novel proteins not previously described on endothelial cells. Objective: This study was performed to identify new molecules which may play a role in HDMEC-melanoma cells binding. Methods: We have generated a monoclonal antibody(Mab) against PMA-stimulated HDMEC. A Mab was evaluated functionally through melanoma cell-endothelial cell adherence assay and characterized by Western immunoblot. Results: Mab EM-71 recognized a molecule with expression levels in vitro that could be upregulated by PMA(EM-71 molecule). The expression of EM-71 molecule on HDMEC was increased in a dose-dependent manner by PMA only, but not affected by interleukin 1 alpha(IL-1α) or tumor necrosis factor alpha(TNFα). PMA augmented melanoma cell adherence to HDMEC, which is coincident with an increase in EM-71 molecule expression on HDMEC by PMA. Mab EM-71 partially inhibited up to 59% of the increased melanoma cell binding to PMA-stimulated HDMEC and failed to block melanoma cell binding to IL-1α or TNFα-stimulated HDMEC. Western immunoblots of lysates of HDMEC demonstrated a 200 kDa protein on HDMEC. Conclusion: This study demonstrates that EM-71 molecule may play a partial role in melanoma binding to PMA-stimulated HDMEC.