Differential expression of vinculin between weakly and highly metastatic B16-melanoma cell lines.

We previously reported on the altered expression of a third actin in mouse-B16 melanoma associated with malignant progression. While further investigating the relationship of cytoskeletal proteins to malignancy, we found that the expression of vinculin was higher in weakly metastatic B16-F1 cells than in highly metastatic B16-F10 cells. By Northern blot analysis, the mRNA expression of vinculin in B16-F1 was also shown to be higher than in B16-F10. Immunofluorescence staining showed a clear dotted distribution of vinculin in B16-F1, but only a weak and diffuse distribution in B16-F10. The dotted distribution tended to be larger in B16-F1 and when cultured on Matrigel and fibronectin than on laminin and type IV collagen. An alteration in the expression of vinculin was also observed in other cell systems. Vinculin was detected in both normal 3Y1 and in relatively weakly malignant transformed 3Y1 cell lines, while vinculin was either scarcely detected or not detected at all in more malignant cell lines. These results suggest that the suppression of vinculin is closely related to malignant progression in both the B16-melanoma and 3Y1 cell systems.