RESUMO
ObjectiveTo determine whether HBV DNA polymerase is associated with T-cell failure and thus mediates the immune escape of HBV-related hepatocellular carcinoma （HCC） tumor cells， and to investigate the specific molecular mechanisms. MethodsLiver cancer cell lines Huh7 and HepG2 stably transfected with HBV DNA polymerase expression plasmid with Flag （Flag-HBV-P） and intercellular adhesion molecule-1 （ICAM1） were co-cultured with Jurkat cells， and MTT assay， qRT-PCR， and ELISA were used to measure Jurkat cell proliferation， activation （CD69 expression）， and secretion of the cytokine IFN-γ. RNA-seq was used to screen for differentially expressed immune-associated molecules between stably transfected cell lines and control cells， and mRNA half-life and protein half-life assays were used to determine the specific levels of the immune-associated molecules that were affected by HBV DNA polymerase. Related websites were used to predict the transcription factors that may bind to the promoter region of this immune-associated molecule， Western blot was used to verify the effect of transcription factors on the immune-associated molecule， and rescue experiment was used to determine whether HBV DNA polymerase affects the expression level of the immune-associated molecule through this transcription factor. The independent-samples t test was used for comparison between two groups. ResultsThe experimental group had significant reductions in Jurkat cell proliferation， activation， and cytokine secretion compared with the control group （all P<0.01）. Compared with the control group， the experimental group （Huh7 and HepG2 cell lines） had significant reductions in the mRNA and protein expression levels of ICAM1 （all P<0.01）. Website prediction identified the ICAM1 promoter and preliminarily highlighted NFKB1， RELA， and STAT3. Compared with the control group， the experimental group （Huh7 and HepG2 cell lines） had a significant reduction in the protein expression level of p65 （all P<0.01）. After p65 overexpression， there was a significant increase in the protein expression level of ICAM1， and after the expression of p65 was reduced， there was a significant reduction in the protein expression level of ICAM1 （all P<0.01）. In the rescue experiment， there was no significant difference in the protein expression level of ICAM1 between the control group and the experimental group after p65 overexpression （all P>0.05）. After the overexpression of ICAM1， there were no significant differences in the proliferation， activation， and cytokine secretion of Jurkat cells between the control group and the experimental group （Huh7 and HepG2 cell lines） （all P>0.05）. ConclusionHBV DNA polymerase downregulates the level of ICAM1 to mediate HCC immune escape by inhibiting the expression of p65 in NF-κB.