INHIBITION OF VLA-4 AND UP-REGULATION OF TIMP-1 EXPRESSION IN B16BL6 MELANOMA-CELLS TRANSFECTED WITH MHC CLASS-I GENES

The effect of MHC class I gene transfection on the metastatic properti es of B16BL6 melanoma cells was investigated. BL6-8 melanoma cells tra nsfected with H-2K(b) or H-2K(d), but not H-2D(d) or H-2L(d), genes sh owed a dramatic reduction in their ability to generate experimental me tastases in immunosuppressed CB6F1 mice, This observation suggested th at some changes in the metastatic phenotype may have been induced in t he H-2K-transfected melanoma cells. Analyses of adhesive and invasive properties of BL6-8 melanoma cells transfected with H-2 class I genes have been performed. We found that the loss of metastatic properties i n the H-2K(b) or H-2K(d) gene-transfected melanoma cells was associate d with reduced adherence to endothelial cells, laminin and collagen IV , decreased ability to form homotypic cell aggregates and with a compl ete loss of VLA-4 integrin expression, In addition, BL6-8 melanoma cel ls transfected with H-2K genes demonstrated reduced ability to invade Matrigel that paralleled up-regulation of TIMP-1 expression. Incubatio n of untransfected BL6-8 clone or B16F1 cells with 5-azacytidine simil arly resulted in up-regulation of TIMP-1, suggesting that the changes in methylation of TIMP-1 gene could be responsible for TIMP-1 expressi on in the H-2K-transfected BL6-8 melanoma cells, Transfection of BL6-8 cells with the H-2D(d)/L-d genes did not affect their adhesive and in vasive properties. Previously we reported that reduction in the metast atic properties of the H-2K(b) transfected cells was associated with a lterations in cell surface carbohydrates with appearance of alpha-gala ctosyl epitopes and reduction in cell surface sialylation, The present data indicate that, in addition to changes in cell surface carbohydra tes, reduction in adhesive properties and up-regulation of TIMP-1 may be responsible for the observed loss of metastatic potential of BL6-8 cells transfected with the H-2K genes. (C) 1998 Lippincott-Raven Publi shers.