Morphological and neoplastic transformation of C3H/10T1/2 Cl 8 mouse embryo cells by insoluble carcinogenic nickel compounds

Abstract

We studied induction of cytotoxicity and morphological transformation in C3H/10T1/2 Cl 8 (10T1/2) mouse embryo fibroblasts by soluble and insoluble carcinogenic nickel compounds. Soluble nickel sulfate and nickel chloride caused dose-dependent cytotoxicity in the concentration range from 0.5 microM to 100 microM after 48 hr treatments, but neither compound induced morphological transformation even at concentrations causing up to 94% cytotoxicity. Insoluble nickel subsulfide, nickel monosulfide, and nickel oxide caused dose-dependent cytotoxicity and a low, dose-dependent frequency of morphological transformation in the concentration ranges from 0.5 to 40 microM, 5 to 50 microM, and 50 to 400 microM, respectively, after 48 hr exposure of cells to these compounds. Foci were predominantly of type II morphology; type III foci were rare. The insoluble nickel compounds studied caused no induction of base substitution mutations to ouabain resistance in 10T1/2 cells over concentration ranges that induced morphological transformation. Nickel subsulfide and nickel monosulfide were taken into cells by phagocytosis, since particles were visible in intracytoplasmic vacuoles. Numerous nickel oxide particles were found associated with cells, but true phagocytic uptake was difficult to detect since no vacuoles were observed. We twice cloned type II and type III foci induced by insoluble nickel compounds, established independent cell lines, and characterized their phenotypes. Four of seven of these cell lines had three- to fourfold increased saturation densities compared to 10T1/2 cells, formed type II and type III foci in reconstruction assays, and grew in soft agarose. One cell line induced by nickel oxide formed tumors in nude mice. These data indicate that insoluble carcinogenic nickel compounds induced type II foci in 10T1/2 cells, some of which were tumorigenic, and that the 10T1/2 cell system is suitable for studying mechanisms of nickel compound-induced morphological transformation in mammalian cells.

Metal mutagenesis in transgenic Chinese hamster cell lines.

“…In our studies with the G12 cells, we could microscopically visualize phagocytized intracellular particles of NiS and Ni3S2 at the end of the 24-hr treatment, but could not see phagocytized particles of NiO (15). Although nickel oxide particles may not be phagocytized as readily as the nickel sulfides (20), there are indications that these particles may remain associated with the cell membranes for long periods (21). Since the treated cells are not disturbed in our assay for up to 6 days after the end of the treatment,, the opportunity exists for useful for defining the mechanisms of prolonged cellular association of the nickel nickel carcinogenesis.…”

Respiratory carcinogenicity assessment of soluble nickel compounds.

“…In vitro, soluble nickel compounds induce essentially the same genotoxic effects as waterinsoluble nickel compounds (e.g., nickel subsulfide) but with lower potency (29)(30)(31). The higher concentrations required to see these effects with soluble nickel compounds are attributed to the less efficient cellular uptake of Ni 2+ ion from soluble than from insoluble nickel compounds.…”

Nickel compounds induce histone ubiquitination by inhibiting histone deubiquitinating enzyme activity

“…However, the mechanisms of tumor formation by nickel exposure remain unclear. Nickel compounds are found to be nonmutagenic in most conventional mutagenesis assays (Biggart and Costa, 1986;Biedermann and Landolph, 1987;Miura et al, 1989;Kargacin et al, 1993), but an epigenetic mechanism has been hypothesized to explain the potent carcinogenic effects of nickel ions (Lee et al, 1995;Broday et al, 1999;Sutherland et al, 2001).…”