Hsp72 mRNA production in cultured human cells submitted to nonlethal aggression by heat, ethanol, or propanol. Application to the detection of low concentrations of chromium(VI) (potassium dichromate)

Abstract

The HT29 and HepG2 human cell lines have been shown to express stress proteins (heat shock proteins, HSP) when submitted to a variety of sublethal environmental aggressions. In the present study, these cells were submitted to standardized mild aggression by heat, ethanol, or propan-1-ol in vitro. Subsequent formation of the hsp72 mRNA was measured by a very specific RNase protection method using a radiolabeled antisense RNA probe. The accumulation of the mRNA coding for the HSP72 stress proteins was found to be maximum within 3 h after the aggression. Results were obtained faster and were much more interpretable than those from the classical method involving the autoradiography of electrophoretically separated ³⁵ S-labeled proteins, especially in the case of very weak, threshold-level, aggressions. When this model was used as a biological system for the detection of low concentrations of chromium(VI) (Cr₂O₇ ^2-), it was possible to detect concentrations as low as 0.5 µmol/L. This indicates that measuring indices of stress induction in human cultured cells can be several orders of magnitude more sensitive than the commercial Microtox assay used for detecting low levels of pollution.