SV40-transformed human cells fail to grow in zinc concentrations which permit normal human fibroblast proliferation

Zinc is a metal known to be required for normal growth of both cells, and organisms. When normal and SV40-transformed human tumor cells are plated and grown in medium containing zinc sulfate, a significant fraction of the transformed cells fail to grow at zinc concentrations which are relatively nontoxic to the normal fibroblasts. Although cultured cells respond to certain metallic ions by increasing their metallothionein content, no difference in the ability of normal and transformed cells to produce metallothionein in response to zinc exposure could be detected, thus ruling out this mechanism as a basis for the differing abilities of the cells to grow in zinc in vitro. These results suggest that zinc may be capable of differentially regulating the growth of normal and SV40-transformed human fibroblasts.