Rs4705342 polymorphism is involved in the tumorigenesis of HBV positive HCC by altering the binding affinity of HBV induced NF-kB with the promoter region of microRNA-143.

The objective of this study was to explore the role of rs4705342 located in the miR-143 promoter in relation to the control of HBV positive HCC and the underlying molecular mechanism. A luciferase assay was performed to explore the factors which influenced miR-143 transcription activity and the target gene of miR-143. This would further be confirmed by ChIP assay. Western blot and real-time PCR were performed to identify the relationship between miR-143 and ORP8. Luciferase activity of miR-143 SNP was increased with the presence of C allele. The presence of T allele partially restored the transcription ability. NF-κB displayed a much higher degree of luciferase activity in relation to the cells transfected with vectors containing either T or C allele rather than control cells with a greater extent in C allele group than T allele group. At the same time, ChIP assay indicated that the affinity of NF-ΚB in the miR-143 promoter was higher in C/C cells. The over-expression of HBX promotes NF-kB expression thus increasing the extent of binding of NF-kB on the CC allele of the miR-143 promoter. The binding is also abolished by NF-kB siRNA. ORP8 was proven to be a target gene of miR-143 using bioinformatics algorithm analysis. It was further confirmed by the luciferase assay that miR-143 substantially inhibited luciferase activities of wild-type ORP8. However, it did not affect the mutant ORP8. HBx induced by HBV infection up-regulated miR-143 expression. NF- kB can partially abolish the promotion effect of HBx on the miR-143 level in cells genotyped as CC but not in cells genotyped as TT. Tissues derived from participants genotyped as CC exhibited a higher level of miR-143, but a lower level of ORP8. The presence of the minor allele of rs4705342 in the promoter of miR-143 attenuated the transcription ability. This promoted ORP8 expression and could be a factor contributing to the oncogenesis in HBV positive HCC.