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(M/MF209) Cytotoxic threshold evaluation of pesticides and related expression of stress proteins in cultured human cells. Soleilhavoup, Jean-Pierre1, Croute, Françoise2, Gaubin, Yolande2, Murat, Jean-Claude1, Beau, Bernadette1, Youcef-Kodja, Dalila1, 1 2 ABSTRACT- Wide use of pesticides in both agricultural and domestic environments requires both better knowledge of their possible noxiousness toward human population and pertinent proposal for biomarkers to detect exposure to low levels of these pollutants. Therefore, threshold concentrations for cytotoxicity of six insecticides of six different chemical families were determined on cultured A549 tumor cells derived from human lung epithelium by monitoring the first sign of cell suffering, i.e., a decrease of cell growth rate after a 4-days exposure to different insecticides concentrations. Toxicity was found to increase as imidacloprid < methomyl < vamidothion < endosulfan < abamectin < bifenthrin with threshold values of 200, 100, 40, 2, 0.9 and 0.5 mgr/ml respectively. Under the same experimental conditions, expression of stress proteins Hsp72 and Grp78 was evaluated by immunodetection on western blots. All insecticides were found to induce an overexpression of Grp78. As expected,indirect immuno-fluorescence study showed that Grp78 localisation in control cells was restricted to the rough endoplasmic reticulum and Golgi apparatus, whereas fluorescence invaded all the volume of exposed cells. This suggests that exposure to the six pesticides leads to an abnormal folding and/or glycosylation of newly synthesized proteins which are trapped by Grp78 and thus accumulate into the cell since they cannot be excreted. Expression level of Hsp72 was variably increased after exposure to imidacloprid, methomyl, endosulfan and bifenthrin which could be the result of an oxidative stress, whereas it was decreased after exposure to vamidothion and abamectin. From our study, it is concluded that Grp78 stress protein could be the most reliable molecular marker for monitoring the safety of pesticide utilization by occupationally exposed workers. Key words: pesticides, cytotoxic threshold, biomarkers, stress proteins |
