Unscheduled DNA synthesis (UDS) induced in vitro by cadmium in tracheal epithelial cells of rat and hamster

Abstract

Cadmium (Cd) is an ubiquitous pollutant of industry and environment. It is known to damage various organs such as bones, lungs and kidneys in m a n and experimental animals (Paterson 1947; Friberg et al., 1986; Foulke 1986). The carcinogenic effects of cadmium exhibit species specificity. Pulmonary tumors induction has been demonstrated after inhalation of several cadmium compounds in rats (Hadley et al., 1979; Takenaka et al., 1983; Oldiges et al., 1989). In contrast, no carcinogenic response has been found in mice and hamsters treated by similar compounds (Glaser, 1989). This discrepancy raises the problem of extrapolation of experimental results t o humans and obviously, there is a need to determine why animal species differ in their response to the metal. However, this response is modulated substantially with the cadmium compound used that indicates the predominant influence of the toxicokinetics of the different forms of inhaled substances. Several toxicokinetic parameters can indeed interact on the induction of carcinogenicity. One of them is the uptake of pollutant particles by target cells which induces directly the cytotoxicity and thegenotoxic effects in these cells. These observations may be especially important for carcinogenesis induced by Cd and ask to be explore.d Genotoxic effects of cadmium were previously demonstrated in in vitro systems (Swierenga et al., 1987; Coogan et al, 1992). Cadmium was shown to induce DNA damage in cultured cells by the action of reactive free radicals (Ochi et al., 1983; Snyder et al., 1988).