SOLUBLE INTERCELLULAR-ADHESION MOLECULE-1 IS RELEASED BY HUMAN-MELANOMA CELLS AND IS ASSOCIATED WITH TUMOR-GROWTH IN NUDE-MICE

We have studied the cytokine regulation of cell surface and soluble intercellular adhesion molecule 1 (ICAM-1) expression on the human melanoma cell line A375M. Unstimulated cells express ICAM-1 on their cell surface but do not secrete significant levels of soluble ICAM-1. Interleukin 1, interleukin 6, tumor necrosis factor, and gamma-interferon all increased cell surface expression of ICAM-1. Tumor necrosis factor, interleukin 1, and gamma-interferon also caused the release of soluble ICAM-1. The serum of melanoma patients has been reported to contain elevated levels of soluble ICAM-1; however, the source of this ICAM-1 is unclear. The serum from nude mice bearing s.c. human melanoma tumors was found to contain soluble human ICAM-1. ICAM-1 levels showed a positive correlation with tumor weight. The release of ICAM-1 from melanoma tumors, in response to host-derived cytokines, may have relevance to immune recognition of the tumor.