A protein reacted with anti-vitronectin antibody accumulates in tumors derived from B16F10 melanoma cells.

Vitronectin is a cell-adhesive glycoprotein in blood plasma and extracellular matrix. We have examined the participation of vitronectin in experimental metastasis of B16F10 mouse melanoma cells which metastasized to lung. By Western blotting, a protein reacted with anti-rat vitronectin antibody was found to be enriched more in the melanoma parenchyma in the lung than the sum of cultured melanoma cells and normal lung tissue. The protein was similarly abundant in tumors of B16F10 cells grown subcutaneously in mice. By immunofluorescence of the tissues, the signal detected with anti-rat vitronectin was found to be localized at nuclei in melanoma cells metastasized in the lung as well as in tumors just grown subcutaneously. These results indicate that the protein reacted with anti-vitronectin antibody is expressed much more in the growing mass of B16F10 melanoma cells in vivo than in vitro.