Carcinogenicity of nickel is the result of its binding to RNA and not to DNA.
In vivo and in vitro studies have shown for the first time that nickel binds maximally to RNA as compared to DNA. The distribution of radiolabeled nickel in various subcellular fractions of liver, kidney, spleen, and lungs of rats has shown that it was mostly localized in the nuclear fraction of each organ, where it was bound to RNA and not to DNA or to proteins. Significant differences between infrared (IR) spectra of RNA and RNA incubated with nickel chloride further corroborate these findings. Parallel experiments with DNA did not show any such effects. Nickel may, therefore, be acting as a carcinogen by controlling gene expression post-transcriptionally.