| Objective:To explore the expression level of protein phosphatase 2A（PP2Ac）protein in human hepatocellular carcinoma（HCC）and precancerous tissues and to investigate the expression levels of PP2Ac-α+βand demethylated PP2Ac protein in human hepatoma cells（hep G2 and Huh-7）after damage by hydrogen oxide（H2O2）oxidating and afafoxin B1（AFB1）poisoning and the effect of damage on hepatoma cells.Methods:1.The HCC tissues of patients who underwent liver tumor resection and diagnosed as HCC by pathology in department of Hepatobiliary Surgery of Guangxi Medical University Cancer Hospital from July 2017 to July 2019 were collected as experimental materials.102 HCC tissues and its precancerous tissues were included.Immunohistochemistry were used to determine the expression of PP2Ac-α+βin HCC and precancerous tissues,and the results were evaluated using a two-point scoring method.Count data were analyzed by chi-square test.2.Hepatoma cells（Hep G2/Huh-7）were treated with different concentrations of H2O2（0,50,100,200,400,800μmol/L）for 2,4,6,and 8hours or AFB1（0,1.25,2.5,5,10,20,and 40μmol/L）for 24 and 48 hours.Cellular morphology was observed by inverted microscope and the activity of hepatoma cells was measured by resazurin assay Western Blot assay was used to determine the expression of PP2Ac-α+βprotein and demethylated PP2Ac protein.An independent sample t-test was used for comparison between the two groups.A one-way analysis of variance was used for comparison between multiple groups,and the two-way analysis of variance was used for factorial design data.Results:1.As for the expression of PP2Ac-α+βprotein in 102 HCC tissues,14cases were negative,20 cases were weakly positive,44 cases were moderately positive and 24 cases were strongly positive expression levels.The low expression（negative and weakly positive）group accounted for 34.3%（35 cases）and the high expression（moderately and strongly positive）group accounted for65.7%（67 cases）.In 102 cases of adjacent tissues,70 cases were negative,26cases were weakly positive,6 cases were moderately positive and 0 cases were strongly positive in expression levels of PP2Ac-α+βprotein.The low expression（negative and weakly positive）group accounted for 94.1%（96 cases）and the high expression（moderately and strongly positive）group accounted for5.9%（6 cases）.The difference between the low expression group and the high expression group in HCC and adjacent tissues is statistically significant（=79.887,P=0.000）.Immunohistochemical results showed that PP2Ac-α+βprotein mainly expresses in the cytoplasm of HCC cells,which increases in human HCC tissues and decreases in the adjacent tissues.2.After acute injury of human hepatoma cells induced by H2O2,there were changes in the cell morphology.There were reductions in the cell activity and increases in the inhibition rate with the increase of H2O2 concentration.The acute hepatoma cell injury model was successfully established after200/400μmol/L H2O2 induction of human hepatoma cells for 2h.3.After chronic injury of human hepatoma cells induced by AFB1,there were changes in the cell morphology.There were reductions in the cell activity and increases in the inhibition rate with the increase of AFB1 concentration.The chronic hepatoma cell injury model was successfully established after 24h induction of human hepatoma cells by 10/20μmol/L AFB1.4.Compared with the control group,the expression levels of PP2Ac-α+βand demethylated PP2Ac protein were increased after inducing Hep G2 with 200μmol/L H2O2 for 2 hours,and the differences were statistically significant（t values were-5.553,-2.990,P values were 0.005 and 0.040,respectively）.Compared with the control group,the expression levels of PP2Ac-α+βand demethylated PP2Ac proteins were increased compared with the control group after inducing Huh 7 with 400μmol/L H2O2 for 2 hours,（t values were 0.073and-5.149,P values were 0.002 and 0.007,respectively）.The results show that PP2Ac-α+βprotein and demethylated PP2Ac protein are highly expressed in human hepatoma cells.5.Compared with the control group,the expression levels of PP2Ac-α+βand demethylated PP2Ac protein were increased after inducing Hep G2 with10μmol/L AFB1 for 2 hours,and the differences were statistically significant（t values were-4.561,-5.788,P values were 0.010 and 0.004,respectively）.Compared with the control group,the expression levels of PP2Ac-α+βand demethylated PP2Ac proteins were increased after inducing Hep G2 with20μmol/L AFB1 for 2 hours（t values were-5.120 and-6.144,P values were0.007and 0.004,respectively）.The results show that PP2Ac-α+βprotein and demethylated PP2Ac protein are highly expressed in human hepatoma cells.Conclusions:PP2Ac-α+βprotein mainly expressed in the cytoplasm of HCC is highly expressed in human HCC tissues.PP2Ac-α+βprotein and demethylated PP2Ac protein are highly expressed in human liver cancer cells（Hep G2/Huh-7）.PP2Ac may participate in the regulation of HCC occurrence and development,and may become a potential and diagnostic new target for anti-HCC. |
