Stress-induced premature senescence as alternative toxicological method for testing the long-term effects of molecules under development in the industry.

No alternative in vitro method exists for detecting the potential long-term genotoxic effects of molecules at subcytotoxic concentrations, in terms of days and weeks after exposure(s) to the molecule tested. A theoretical model of cellular senescence led to the concept that subcytotoxic stresses under any molecules at subcytotoxic doses, such as molecules under development in the pharmaceutical, cosmetics and food industry, might lead human fibroblasts into a state closely related to in vitro senescence. This concept was then experimentally confirmed in vitro: many biomarkers of replicative senescence of human fibroblasts were found 72 h after their exposure to various kinds of stressors used at non-cytotoxic concentrations. This phenomenon has been termed stress-induced premature senescence (SIPS). Moreover, proteomics studies have revealed that, besides their effects on the appearance of the biomarkers of senescence, sublethal stresses under a variety of stressors also lead to long-term specific changes in the expression level of proteins which are stress-specific. These changes have been coined the molecular scars of stress. The proteins corresponding to these molecular scars may be identified using the latest developments in mass spectrometry. This model of stress-induced premature senescence may be applied to the toxicological sciences when testing for the potential irreversible long-term effects of molecules on the cell fate.