Inhibition of motility and invasion of B16 melanoma by the overexpression of cystatin C.

Although increased expression of cysteine proteinases has been shown to be correlated with increased metastasis for a wide variety of tumours, the contribution of cysteine proteinases to the metastatic spread of tumour cells is not well understood. In order to examine this question we have overexpressed a specific cysteine proteinase inhibitor, cystatin C, by stable transfection of B16F10 melanoma. Increased expression of cystatin C inhibited motility and in vitro invasiveness of B16 melanoma by 50% in both stimulated (autocrine motility factor, laminin) and unstimulated cells. These results suggest that cysteine proteinases are involved in B16 melanoma motility and invasion.