Effects Of KLF4 On Hepatocyte Apoptosis In Chronic Liver Injury And The Underlying Mechanism

Objective:To investigate the expression of Krüppel-like factor 4（KLF4）in chronic liver injury as well as its effects and mechanism on hepatocyte apoptosis by in vivo and in vitro experiments.Methods:（1）The expression of KLF4 in liver tissues of 35 patients with chronic hepatitis B（CHB）were detected by immunohistochemical method,and then was compared with that in liver tissues of 10 patients with liver trauma to analyze the expression pattern of KLF4 in chronic liver injury.（2）The liver injury was induced by carbon tetrachloride（CCl₄）for 4 and 8 weeks respectively,and the model of chronic liver injury was established.The expression of KLF4 in liver and its relationship with oxidative stress and apoptosis in chronic liver injury were studied.（3）To investigate the effects of oxidative stress on KLF4 expression and hepatocyte apoptosis in L02 cells（normal human hepatocytes）induced by（hydrogen peroxide,H₂O₂）.（4）To explore the mechanism of oxidative stress regulating the expression of KLF4 in hepatocytes by knocking down the expression of RELA（an important subunit of nuclear factor-κB）by short hairpin RNA（sh RNA）specific to RELA gene.（5）To explore the regulatory effect and mechanism of KLF4 on oxidative stress and apoptosis of hepatocytes by pre-interfering with H₂O₂-induced L02 cells by KLF4gene specific sh RNA.Results:（1）Compared with the control group,the expression of KLF4 in liver tissue of CHB patients was significantly increased,and the positive staining of hepatocyte nucleus was the most significant（P<0.01）.（2）Compared with the control group,CCl₄ induced oxidative stress and apoptosis of hepatocytes in mice with chronic liver injury,accompanied by increased expression of KLF4（P<0.01）;The localization of up-regulated KLF4 was similar to that of hepatitis B patients,and significantly increased in hepatocyte nucleus.（3）Compared with the control group,the expression of KLF4,uncoupling protein 2（UCP2）and apoptosis of L02 cells induced by hydrogen peroxide increased in vitro（P<0.05）.（4）Compared with the control group,the expression of KLF4 and UCP2 decreased,oxidative stress and apoptosis increased after RELA knockdown（P<0.05）.（5）Compared with the control group,the expression of UCP2 decreased,oxidative stress and apoptosis increased after KLF4 knockdown（P<0.05）.Conclusion:Oxidative stress in hepatocytes can up-regulate the expression of KLF4 in hepatocytes by activating nuclear factor-κB signal in chronic liver injury;Up-regulated KLF4 can inhibit oxidative stress by increasing the expression level of UCP2,and alleviate hepatocyte apoptosis and liver injury.