In vitro electron microprobe of carcinogenic nickel compound interaction with tumor cells

Some nickel compounds (Ni3S2,Ni) induce tumours in muscle, while others have no effect (NiO). It has been suggested that the carcinogenicity of nickel is related to its penetrating power (phagocytosis) in transformed cells. The penetration of various nickel salts into cultured rhabdomyosarcoma cells (RhC) was studied. Electron microscopy and microanalysis were used to study the ultrastructure and intracellular localization of nickel in ultra-thin sections. Nickel subsulfide (Ni3S2) and nickel oxide (NiO) penetrated into cells and were concentrated in vacuoles, exhibiting a particular affinity for membrane structure. They subsequently appeared to be eliminated in the extracellular medium. Colloidal nickel and iron carbonyl, on the other hand, did not penetrate these cells. Various tumoral and normal cells were compared for their ability to phagocytose Ni3S2; it was found that these compounds penetrated only RhC and macrophages. In vivo studies have demonstrated the various carcinogenic properties of nickel and two of its salts. Comparison with in vitro results suggests that the phagocytosis of nickel compounds is not directly related to eventual induction of a tumour. No nuclear localization could be detected, but a mechanism for concentration and elimination of these compounds, and especially for rhabdomyosarcoma tumour cells, was suggested.