Identification of genes that are induced after cadmium exposure by suppression subtractive hybridization

The heavy metal cadmium is a xenobiotic toxicant of environmental and occupational concern and it has been classified as a human carcinogen. Inhalation of cadmium has been implicated in the development of emphysema and pulmonary fibrosis, but, the detailed mechanism by which cadmium induces adverse biological effects is not yet known. Therefore, we undertook the investigation of genes that are induced after cadmium exposure to illustrate the mechanism of cadmium toxicity. For this purpose, we employed the polymerase chain reaction (PCR)-based suppression subtractive hybridization (SSH) technique. We identified 29 different cadmium-inducible genes in human peripheral blood mononuclear cells (PBMCs), such as macrophage migration inhibitory factor (MIF), lysophosphatidic acid acyltransferase-alpha, enolase-1alpha, VEGF, Bax, and neuron-derived orphan receptor-1 (Nor-1), which are known to be associated with inflammation, cell survival, and apoptosis. Induction of these genes by cadmium treatment was further confirmed by semi-quantitative reverse-transcription PCR. Further, we found that these genes were also induced after cadmium exposure in normal human lung fibroblast cell line, WI-38, suggesting potential use of this induction profile to monitor cadmium toxicity in the lung.