Studies on the interaction between Cd(2+) ions and nucleobases and nucleotides

Cadmium is a potent carcinogen in rodents and has recently been accepted by the International Agency for Research on Cancer as a category 1 (human) carcinogen, but the molecular mechanism of its action remains largely unclear. It has however been suggested that cadmium-induced carcinogenesis may involve either direct or indirect interaction of Cd(2+) with DNA. In this study it is found that when Cd(2+) is allowed to interact with adenine and guanine, there is a marked change in the high performance liquid chromatography (HPLC) retention time for adenine but not for guanine. Since Cd(2+) is believed to bind covalently to adenine and guanine, the changes in retention time but absence of any cadmium in the peak fraction point to the following: (i) lability of cadmium-nucleobase adducts, and (ii) introduction of some kind of chemical modification in adenine but not in guanine as a result of covalent binding. This result is different from that for Ni(2+) in which case a change in retention time was observed for guanine but not for adenine.