The Molecular Mechanisms Of Cisplatin-induced HBV Reactivation And Acute Liver Injury

HBV infection is a major worldwide health problem with more than two billion infected people and 400 million chronic carriers (three-quarters of them in China), who are at high risk for developing acute and chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC), which leads to more than one million deaths annually and half of them in China. At the same time, according to the world health organization, the malignant tumor is still the leading cause of death in humans currently. The number of cancer patients with combination of HBV infection is large, when these patients undergoing chemotherapy or immunosuppressive therapy, some of these patients will occur the phenomenon of HBV reactivation, a large amount of instantaneous activation in patients with HBV may cause severe liver damage and even liver failure, which will result in slow or interrupt in treatment, and then the effective treatment of cancer patients will be delayed, which will seriously affect the prognosis and even endanger their lives.At home and abroad in recent years, there has been a number of clinical experiments which have established that the cisplatin can induce HBV reactivation, which could cause the replication of HBV, acute liver injury or liver failure, which increased the fatality rate dramatically. Nevertheless, the molecular mechanism relating to HBV reactivation caused by cytotoxic chemotherapy such as cisplatin still remains unknown. In this study, firstly, we successfull established a simple, versatile, and reproducible HBV persist infection model in vitro (Huh7 and SMMC7721 cells) and in vivo (Nude and C57BL/6J mice) with the circularized HBV DNA. The infection effect and replication efficiency of the circularized HBV DNA is significantly better than that of the linear HBV DNA (P< 0.05), the circularized HBV DNA could completely simulate the HBV cccDNA in the structure without the interference of exogenous factors, which could reflect the basic pathophysiological procedure of HBV infection and then provide powerful basis for further experimental study. Secondely, the methods of qRT-PCR, RT-PCR, ChIP, Southern blot and Western blot were used to confirmed that in vitro (HepG2-HBV1.1, Hep AD38 and Primary hepatocytes cells) and in vivo (HBV hydrodynamic model and HBV transgenic mice):The cisplatin could directly raise the HBV cccDNA, PGC-la and HNF-4a, which could increase the activity of HBV core promoter. The capacity of HBV replication raised in transcription level that could eventually increase the HBV DNA level significantly. Finally, the mainly molecular mechanisms of cisplatin-induced acute liver injury as showned in the following two aspects:on the one hand, the methods of qRT-PCR, RT-PCR, ChIP, Western blot, BrdU, trypan blue staining, immunohistochemical and flow cytometry experiment were used to confirmed that the cisplatin could significantly induce cell endoplasmic reticulum stress and a large number of production of ROS, which in turn lead to cell apoptosis and eventually lead to acute liver cell damage or liver failure. On the other hand, the methods of RT-PCR, ChIP, Western blot, siRNA, analysis of gene expression profile ChIP and immunohistochemical experiment were used to confirmed that the cisplatin could significantly induce the production of Alix protein, which could increase the direct release of HBV core particle, the significant increase of HBcAg as a strong immunogen, which could directly stimulate the strong humoral immune response, in particular, which in turn lead to acute injury of liver cells and liver failure. Finally, we found that the curcumin and NAC were the key targets to curb the phenomenon of HBV reactivation.To sum up, cisplatin could directly raise the level of HBV cccDNA, PGC-la and HNF-4a, which could upregulate HBV core promoter activity and sharply enhanced virus replication. Also, cisplatin induced cell endoplasmic reticulum stress and a large number of production of ROS and HBV core particle, which in turn may lead to stimulate the strong humoral immune response and cell apoptosis, and eventually lead to acute liver cell damage or liver failure. This study could lay a solid foundation for settle the clinical HBV reactivation fully.