Protective Effects And Mechanisms Of Quercetin On HL-7702 Cell Damage Induced By O,p’-DDT

Persistent organic pollutants (POPs) are a class of compounds, which have good chemical stability, difficult to degradation in the environment, easy to accumulate in the fat tissue, and accumulate in the food chain. DDT is a kind of typical POPs and has been banned for many years, but DDT still is detected in environmental and foods. DDT can be a serious threat to human health. Especially, liver is an important detoxification organ, which is vulnerable to DDT. DDT can cause liver damage and even liver cancer. Quercetin is a kind of flavonoids, which widely exists in plants. It has been reported that quercetin has antioxidant and anti-inflammatory, antiviral and anticancer functions. Many studies have shown that quercetin can suppress the liver injury induced by a variety of exogenous compounds. However, antagonistic effect and mechanism of quercetin on liver cell injury induced by DDT have not been reported. The aim of this study was to detect the antagonistic effect of quercetin on o,p’-DDT-induced toxicity in HL-7702 cells. The research includes the following parts:The first part:MTT assay was used for measure the effect of quercetin on o,p’-DDT-induced HL-7702 cell survival. LDH assay was used for detect the effect of quercetin on o,p’-DDT-induced HL-7702 cell release lactate dehydrogenase. The results showed that o,p’-DDT can induces cytotoxicity in HL-7702 cell, however, quercetin can notably weaken the effects of o,p’-DDT.The second part:Single cell gel electrophoresis experiment was used for detect the degree of single stranded DNA damage. Micronucleus test was used for detect the frequencies of micronucleated cells. DNA protein cross-linking experiment was used for detect the formation of DPC. The results showed that o,p’-DDT can induce genotoxicity in HL-7702 cell, however, quercetin alleviated o,p’-DDT-induced genotoxicity efficiently.The third part:DAPI staining was used to detect the effects of quercetin on o,p’-DDT induced-apoptosis corpuscle in HL-7702 cells; Annexin V-FITC/PI flow analysis tests the impacts of quercetin on o,p’-DDT induced-apoptosis in HL-7702 cell; Effects of quercetin on o,p’-DDT induced-changes in mitochondrial membrane potential was measured using JC-1; Western blotting was employed to detect effects of quercetin on o,p’-DDT induced-changes in mitochondrial apoptosis related proteins. The results showed that o,p’-DDT can induce apoptosis of HL-7702 cells, and quercetin can antagonize o,p’-DDT-induced liver cell apoptosis through adjusting mitochondrial apoptosis-related proteins.The fourth part:Effects of quercetin on o,p’-DDT induced-oxidative stress in HL-7702 cells is investigated through detecting ROS production GSH contents、SOD and CAT, activities; Effects of quercetin on o,p’-DDT induced- NADPH oxidase changes is detected by QT-PCR; Effects of quercetin on o,p’-DDT induced-Nrf2 distribution in cytoplasm and nucleus is detected by western blotting. The results showed that quercetin can antagonize o,p’-DDT induced-liver cell oxidative stress by inhibiting the NADPH oxidase、induction of Nrf2 from cytoplasm to nucleus, activating antioxidant enzymes. Taken together, quercetin could suppress o,p’-DDT induced-oxidative stress levels through inhibiting NADPH oxidase、 promoting Nrf2 nuclear transfer, activating liver cell antioxidant enzyme activities, which thus antagonized o,p’-DDT induced-cell toxicity, genetic toxicity and apoptosis inHL-7702 cells.