Effects of prometryn on cardiac and liver cell lines and mouse tissues

Abstract

BackgroundPesticides are important biological agents that deter or kill pests. Globally, about 2 million tons of pesticides are being utilized each year which highlights their importance. Previous studies have suggested that high levels of pesticide exposure are associated with increased risk of chronic diseases, including cancers, cardiotoxicity, Parkinson’s disease, diabetes mellitus, neurological deficits, birth defects, and reproductive disorders. Prometryn is a commonly used selective triazine herbicide, which is currently used as an alternative to atrazine‐based products. It is widely applied to agriculture as it has lower acute toxicity than atrazine herbicides, stable chemical properties, and a long period of effectiveness. Although past studies have shown that triazine herbicides have carcinogenic potential in humans, the cytotoxic effects of prometryn on cardiac and hepatic systems are not well investigated or understood. The aim of this study was to determine the effects of prometryn on the heart and liver.MethodsH9c2 cardiac and HepG2 liver carcinoma cells were used to study the in‐vitro effects of prometryn. Cells were treated with varying concentrations of prometryn for 24 h. Cell viability, mitochondrial membrane potential, and reactive oxygen species (ROS) levels were assessed. For animal studies, male mice (10 weeks old) (n=24) were randomized to two treatment groups (control and prometryn). The control group received corn oil while the prometryn treated group were exposed to 185mg/kg b.w. prometryn dissolved in corn oil every 48 hours for 7 days. After a total of 4 doses, mice were euthanized, and the heart and liver tissues were collected. Proteasome and immunoproteasome activity were measured in the heart and liver. Protein expression levels of markers for oxidative stress, apoptosis, and proteasomal degradation such as GSTT2, GSTA1/2, Hsp70, Hsp27, NADPH oxidase, PARP‐1, p53, PSMD12, LMP2, DNP, VU‐1 were detected using immunoblotting. Protein oxidation and polyubiquitination were detected as an indicator of oxidative stress. A paired t‐test was used to assess group differences for protein levels and p values <0.05 were deemed statistically significant.ResultWe found that prometryn had a concentration‐dependent effects on H9c2 and HepG2 cell lines when we assessed cell viability, mitochondria function, and total intracellular reactive oxygen species formation. Increasing the concentration of prometryn increased the ROS formation, decreased cell viability and decreased mitochondrial membrane potential in these cell lines. Furthermore, in animal studies we observed changes in the proteasome and immunoproteasome activities in the liver but not in the heart. Changes in protein expression levels of oxidative stress and proteasomal degradation markers were only detected in the liver.ConclusionThese results indicate that H9c2 and HepG2 cells are sensitive to prometryn in‐vitro. However, prometryn effects on the heart and liver tissue in male mice is significantly different. Overall, our data supports the deduction that prometryn affected mitochondrial function, induced oxidative stress in cells, but also alters the ubiquitin‐proteasome system and increases oxidative stress in mice liver. These results help towards elucidation of the mechanism by which prometryn could cause diseases.