Upregulation of stress response mRNAs in COS-7 cells exposed to cadmium

Exposure of cells to cadmium (Cd) is known to stimulate the expression of various types of genes. These changes in gene expression are presumed to be related to the cellular response to Cd toxicity. To better understand the mechanisms related to Cd toxicity, suppression subtractive hybridization was carried out on COS-7 cells (African green monkey kidney cells) and the gene expression induced by Cd exposure was investigated. Heat shock protein (hsp) 10, 40, 60, 70, 89alpha and metallothionein II (MTII) mRNAs were found to be induced by Cd. This is the first report to describe the Cd-inducibility of hsp10, 40 and 89alpha mRNAs. Semi-quantitative reverse-transcription polymerase chain reaction showed the diverse expression patterns of these genes, depending on Cd concentration and exposure time. A marked elevation of hsp70 mRNA and induction of mRNA for the co-chaperone, hsp40, were detected. A relatively low level of hsp10 and hsp60 mRNAs was induced, with only a 2-fold increase within 24 h. Hsp89alpha mRNA was induced shortly after Cd exposure. These various induction patterns suggest that hsps play different roles in the cell against Cd toxicity.