Hepatitis B virus X protein accelerates hepatocarcinogenesis with partner survivin through modulating miR-520b and HBXIP

Abstract

BackgroundHepatitis B virus X protein (HBx) plays crucial roles in hepatocarcinogenesis. However, the underlying mechanism remains elusive. We have reported that HBx is able to up-regulate survivin in hepatocellular carcinoma tissues. The oncopreotein hepatitis B X-interacting protein (HBXIP), a target of miR-520b, is involved in the development of cancer. In this study, we focus on the investigation of hepatocarcinogenesis mediated by HBx.MethodsThe expression of HBx and survivin was examined in the liver tissues of HBx-Tg mice. The effect of HBx/survivin on the growth of LO2-X-S cells was determined by colony formation and transplantation in nude mice. The effect of HBx/survivin on promoter of miR-520b was determined by Western blot analysis, luciferase reporter gene assay, co-immunoprecipitation (co-IP) and chromatin immunoprecipitation (ChIP), respectively. The expression of HBx, survivin and HBXIP was detected by immunohistochemistry and real-time PCR in clinical HCC tissues, respectively. The DNA demethylation of HBXIP promoter was examined. The functional influence of miR-520b and HBXIP on proliferation of hepatoma cells was analyzed by MTT, colony formation, EdU and transplantation in nude mice in vitro and in vivo.ResultsIn this study, we provided evidence that HBx up-regulated survivin in the liver cancer tissues of HBx-Tg mice aged 18 M. The engineered LO2 cell lines with survivin and/or HBx were successfully established, termed LO2-X-S. MiR-520b was down-regulated in LO2-X-S cells and clinical HCC tissues. Our data revealed that HBx survivin-dependently down-regulated miR-520b through interacting with Sp1 in the cells. HBXIP was highly expressed in LO2-X-S cells, liver cancer tissues of HBx-Tg mice aged 18 M and clinical HCC tissues (75.17%, 112/149). The expression level of HBXIP was positively associated with those of HBx or survivin in clinical HCC tissues. In addition, we showed that HBx survivin-dependently up-regulated HBXIP through inducing demethylation of HBXIP promoter in LO2-X-S cells and clinical HCC tissues. In function, low level miR-520b and high level HBXIP mediated by HBx with partner survivin contributed to the growth of LO2-X-S cells in vitro and in vivo.ConclusionHBx accelerates hepatocarcinogenesis with partner survivin through modulating tumor suppressor miR-520b and oncoprotein HBXIP.

Hepatitis B Virus Regulates Apoptosis and Tumorigenesis through the MicroRNA-15a-Smad7-Transforming Growth Factor Beta Pathway

“…For example, HBV mRNA can reduce the level of miR-122 by direct absorption to promote hepatocellular carcinoma tumor growth (11), and the HBx protein modulates the tumor suppressor miR-520b, accelerates hepatocarcinogenesis, and represses miR-148a to inhibit the AKT/ ERK/FOXO4/ATF5 pathway (9,36). It has been reported that miR-15a plays important roles in apoptosis, cell proliferation, and tumorigenesis by targeting different mRNAs in various cancers (13,37,38).…”

Targeted multidrug-resistance reversal in tumor based on PEG-PLL-PLGA polymer nano drug delivery system

“…Positive cells were scored as follows: ,10% as negative, "-"; 3%-10% as low expression, "+"; 30%-50% as moderate expression, "2+"; positive cells .50% as strong expression, "3+"; the latter three categories represent positive expression of marker proteins. 21 …”

Influence of miR‐520e‐mediated MAPK signalling pathway on HBV replication and regulation of hepatocellular carcinoma cells via targeting EphA2

“…According to the results, the remarkably reduced miR‐520e was observed in Huh7‐X and HepG2‐X cells, but it presented a significant increase in a dose‐dependent manner in Huh7‐X, HepG2‐X and HepG2.2.15 cells after interfering HBx, which indirectly confirmed that HBx could downregulate the expression of miR‐520e. Interestingly, Zhang et al also reported that HBx can reduce the expression of miR‐520b, a member of miR‐520 family, by forming complex with transcription factor Sp‐1 and survivin in liver cells, which also provided the possibility that the downregulation of miR‐520e in HBV‐positive HCC cells may result from the inactivation of miR‐520e promoter caused by the interaction between HBx and Sp‐1.…”

“…To date, there was evidence indicated that miR‐520 family, served as anti‐onco‐miRNAs, was implicated in regulating the tumorigenesis and development of various solid cancers . To be specific, miR‐520b, as a member of miR‐520 family, was reduced, while its target gene ( HBXIP ) was elevated, both of which were mediated by HBx, contributing to hepatocarcinogenesis in vitro and in vivo . Of note, as another member of miR‐520 family, miR‐520e was also reported able to target NF‐kappaB‐inducing kinase (NIK) to mediate NIK/phosphorylated extracellular signal‐regulated kinase 1/2 (p‐ERK1/2)/Nuclear factor kappa‐B (NF‐κB) pathway, and thereby inducing the occurrence of HCC .…”