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, and binds to two sites in the mouse c‐myc promoter. We report the effect of over‐expression of ZF5 on cell growth. ZnCl(2) 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 fivefold 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.