RESUMO
Chronic hepatitis B virus (HBV) infection is a primary cause for liver cancer. And the main challenge of curing hepatitis B is the elimination of the stable covalently closed circular DNA (cccDNA) of the viral genome. The formation of HBV cccDNA requires the filling of single-stranded region and the ligation of nicks in relaxed circular DNA (rcDNA) strands. Previously, our group reported that proliferating cell nuclear antigen (PCNA) was involved in the formation of HBV cccDNA. However, the underlying mechanism of the conversion of HBV rcDNA to cccDNA is poorly understood. In the present study, we aim to explore the mechanism by which PCNA contributes to the conversion of HBV rcDNA to cccDNA. Our data showed that PCNA was involved in the process of HBV rcDNA repair. The knockout of PCNA by the CRISPR/Cas9 system remarkably blocked the conversion of HBV rcDNA to cccDNA, while the ectopic expression of PCNA could effectively rescue the event (P<0. 001). Knockout of PCNA significantly slowed down the conversion kinetics of HBV rcDNA to cccDNA (P<0. 01). Mechanically, the DNA binding domain of PCNA was required for the process of HBV rcDNA repair to cccDNA (P<0. 01). Thus, we conclude that PCNA confers the conversion of HBV rcDNA to cccDNA by its DNA binding domain. Clinically, PCNA might serve as a novel target for antiviral therapy.
RESUMO
To explain biological function of protein CCL15 in HCC cell lines. The different expression level of CCL15 among HCC cell lines was validated by RT-PCR and Western blot. The expression recombinant plasmid of siRNA-CCL15 was constructed successfully and transfected into high metastasis cell lines HCCML3 to observe the alteration of biological function of HCCML3. The overexpression of CCL15 in high metastasis HCC cell lines was confirmed by validation tests. After transfected with siRNA-CCL15, the average amounts of invaded cells in cell invasion assay were 657.9 (HCCML3) and 148.4(HCCML3-siCCL15) (t=19.34, P less than 0.05). And in the scratch assay, the migrating distance were (0.35+/-0.02) mm (HCCML3) and (0.82+/-0.03)mm (HCCML3-siCCL15) (t=15.67, P less than 0.05). The expression of MMP-9 in HCCML3 was higher than HCCML3-siCCL15 through Western blot. Some biological properties (migration, invasion, MMP-9) of HCCML3 transfected with siRNA-CCL15 were decreased. The results suggest CCL15 might play an important role in HCC cell invasion and metastasis through two paths of MMPs regulation and invasion potential strengthening.
