OVER-EXPRESSED ZF5 GENE-PRODUCT, A C-MYC-BINDING PROTEIN RELATED TO GL1-KRUPPEL PROTEIN, HAS A GROWTH-SUPPRESSIVE ACTIVITY IN MOUSE-CELL LINES

ZF5 encodes a zinc finger protein, which contains five C2H2-type zinc fingers showing homology with the zinc finger of the Kruppel family, a nd binds to two sites in the mouse c-myc promoter. We report the effec t of over-expression of ZF5 on cell growth. ZnCl2 treatment suppressed the growth of a mouse fibroblast cell line (L cells) transfected with the wild-type ZF5 gene driven by the metallothionein promoter. Cells transfected with the wild-type ZF5 gene formed colonies two- to fivefo ld less efficiently than those transfected with the mutant ZF5 gene in P19, NIH3T3, 3T3-L1 and L cells. Over-expression of ZF5 did not cause c-myc down regulation or arrest of the cell cycle, but increased the DNA content.