CADMIUM-RESISTANT VARIANT OF THE CHINESE-HAMSTER (CHO) CELL WITH INCREASED METALLOTHIONEIN INDUCTION CAPACITY

The toxic trace metal Cd2+ has been used to select a variant (designated Cdr) of the Chinese hamster cell (line CHO) resistant to the growth-inhibitory and cytotoxic effects of Cd2+. Resistance of the Cdr cell to Cd2+-mediated cytotoxicity is not due to a decreased capability of the Cdr cell to accumulate Cd2+ since Cd2+ uptake in the Cdr cell is indistinguishable from that in the CHO cell at both toxic and subtoxic Cd2+ exposures. Comparison of the relative capacities of these two cell types to induce specific low molecular weight Cd2+-binding proteins (metallothioneins) reveals that the Cdr cell has an increased capacity to induce metallothionein and to sequester intracellular Cd2+ in metallothioneins. These results suggest that the greater competence of the Cdr cell to induce metallothionein is a major factor in the Cd2+-resistant phenotype of the variant. © 1979.