Anti-gicerin Antibody Suppresses Early Pulmonary Metastatic Colonization of B16F10 Melanoma Cells.

BACKGROUND/AIM: Adhesion of circulating melanoma cells to the pulmonary vascular bed is a critical early step in hematogenous metastasis. Gicerin is an immunoglobulin superfamily cell adhesion molecule that can mediate homophilic cell-cell adhesion. We examined whether gicerin is expressed in B16F10 melanoma cells and pulmonary tissue and whether systemic anti-gicerin antibody suppresses experimental pulmonary colonization. MATERIALS AND METHODS: Gicerin expression was examined by immunofluorescence staining in cultured B16F10 cells, subcutaneous B16F10 tumors, pulmonary metastatic foci, and normal lung tissue, with matched rabbit pre-immune IgG controls processed in parallel. Histopathological features of subcutaneous and pulmonary lesions were evaluated by hematoxylin and eosin staining. Nude mice received a tail-vein injection of B16F10 cells followed immediately by intravenous administration of matched rabbit pre-immune IgG or rabbit polyclonal anti-gicerin IgG. Cell proliferation, adhesion to human umbilical vein endothelial cells (HUVECs), and wound-healing migration were assessed in vitro. RESULTS: Gicerin immunoreactivity was detected in cultured B16F10 cells, subcutaneous tumors, pulmonary metastatic foci, and normal pulmonary structures, whereas matched rabbit pre-immune IgG controls showed no specific fluorescence, supporting staining specificity under the assay conditions. Tail-vein injection produced early pulmonary metastatic foci, and anti-gicerin IgG at 10 μg/mouse significantly reduced metastatic colonization compared with pre-immune IgG, whereas the 1 μg/mouse dose did not. Anti-gicerin IgG significantly inhibited B16F10 adhesion to HUVEC monolayers and significantly reduced cell migration without significantly affecting cell proliferation. CONCLUSION: Gicerin contributes to early pulmonary colonization of B16F10 melanoma cells by supporting tumor-endothelial adhesion and tumor-cell migration. Gicerin blockade may represent a potential strategy for preventing hematogenous dissemination of melanoma.