Effects of cadmium chloride on some mitochondria-related activity and gene expression of human MDA-MB231 breast tumor cells

It was reported that cadmium is able to exert a cytotoxic effect on tumor MDA-MB231 cells, which shows signs of "non-classical" apoptosis and is characterized by drastic changes in gene expression pattern. In this study, we have extended our knowledge of metal-breast cancer cell interactions by analyzing some mitochondria-related aspects of the stress response to CdCl(2) at either 5 or 50 microM 24- or 96-h exposure, by cytochemical, conventional PCR and Northern/Western blot techniques. We demonstrated that (i) no modification of the mitochondrial mass was detectable due to CdCl(2) exposure; (ii) the respiration activity appeared to be increased after 96-h exposures, while the production of reactive oxygen species was significantly induced, as well; (iii) hsp60, hsp70, COXII and COXIV expressions were dependent on the duration of Cd exposure; (iv) a different hsp60 protein distribution was observed in mitochondrial and post-mitochondrial extracts and (v) 96-h exposure induced the over-expression of hsc/hsp70 proteins and, conversely, the down-regulation of cytochrome oxidase subunits II and IV. These observations, in addition to providing more information on the cellular and molecular aspects of the interaction between CdCl(2) and MDA-MB231 breast tumor cells, contribute to the comprehension of the intracellular molecular mechanisms implicated in the regulation of some mitochondrial proteins.