Centrosomal protein TAX1BP2 inhibits centrosome-microtubules aberrations induced by hepatitis B virus X oncoprotein

The Prognostic Significance of the TEAD4 in Hepatocellular Carcinoma

Background

Abnormal expression of genes causes tumorigenesis, tumor progression, and poor prognosis in hepatocellular carcinoma (HCC). Therefore, the aims of this study were to explore the transcription enhancer domain factor 4 (TEAD4) in patients with liver cancer and its relationship with prognosis.

Methods

HTSeq-FPKM data and corresponding clinical data of HCC patients were obtained from The Cancer Genome Atlas (TCGA). Difference in TEAD4 expression between normal and tumor and the correlation with clinical characteristics were analyzed by the chi-squared test based on UALCAN. HepG2 cell lines were used to study the effect of TEAD4 on HCC cell lines. The expression and clinical significance of TEAD4 in HCC were detected in clinical cases.

Results

The transcription and post-transcription levels of TEAD4 were higher in HCC tumors than normal illustrated different expressed transcription of TEAD4 in gender, nodal metastasis status, tumor grades, and individual cancer stages. The high TEAD4 expression was significantly associated with tumor grades. The high expression of TEAD4 was significantly correlated to shorter 2-5 years overall survival. Inhibition of TEAD4 expression in HepG2 cells resulted in significantly decreased cell proliferation and invasion.

Conclusion

TEAD4 was identified as an independent prognostic factor, and inhibition of TEAD4 expression in HepG2 cells resulted in significantly decreased cell proliferation and invasion.

Microtubules and viral infection

Microtubules (MTs) form rapidly adaptable, complex intracellular networks of filaments that not only provide structural support, but also form the tracks along which motors traffic macromolecular cargos to specific sub-cellular sites. These dynamic arrays play a central role in regulating various cellular processes including cell shape and motility as well as cell division and polarization. Given their complex organization and functional importance, MT arrays are carefully controlled by many highly specialized proteins that regulate the nucleation of MT filaments at distinct sites, their dynamic growth and stability, and their engagement with other subcellular structures and cargoes destined for transport. This review focuses on recent advances in our understanding of how MTs and their regulatory proteins function, including their active targeting and exploitation, during infection by viruses that utilize a wide variety of replication strategies that occur within different cellular sub-compartments or regions of the cell.

Hepatitis B Virus Induces Microtubule Stabilization to Promote Productive Infection through Upregulating Microtubule-associated Protein 1S

BACKGROUND AND AIMS

Continuous release and transmission of hepatitis B virus (HBV) is one of the main factors leading to chronic hepatitis B (CHB) infection. However, the mechanism of HBV-host interaction for optimal viral transport is unclear. Hence, we aimed to explore how HBV manipulates microtubule-associated protein 1S (MAP1S) and microtubule (MT) to facilitate its transport and release.

METHODS

The expression of MAP1S or acetylated MT was investigated by immunofluorescence, RT-PCR, immunoblotting, and plasmid transfection. MAP1S overexpression or knockdown was performed by lentiviral infection or sh-RNA transfection, respectively. HBV DNA was quantified using q-PCR.

RESULTS

Significantly higher level of MAP1S in HepG2215 cells compared with HepG2 cells was detected using RT-PCR (p<0.01) and immunoblotting (p<0.001). Notably, stronger MAP1S expression was observed in the liver tissues of patients with CHB than in healthy controls. MAP1S overexpression or knockdown demonstrated that MAP1S promoted MT acetylation and reduced the ratio of HBV DNA copies inside to outside cells. Further, transfection with the hepatitis B virus X protein (HBx)-expressing plasmids induced significantly higher level of MAP1S than that in controls (p<0.0001), whereas HBVX^- mutant-encoding HBV proteins (surface antigen, core protein, and viral DNA polymerase) hardly affected its expression.

CONCLUSIONS

These results demonstrate that HBx induces the formation of stable MTs to promote the release of HBV particles through upregulating MAP1S. Thus, our studies delineate a unique molecular pathway through which HBV manipulates the cytoskeleton to facilitate its own transportation, and indicate the possibility of targeting MAP1S pathway for treatment of patients with CHB.

The Effects and Underlying Mechanisms of Hepatitis B Virus X Gene Mutants on the Development of Hepatocellular Carcinoma

We aimed to elucidate the mechanism by which hepatitis B virus X (HBx) mutations increase the occurrence of hepatocellular carcinoma (HCC) and identify novel putative therapeutic targets. Wild-type HBx (WT-HBx) and four HBx mutants (M1, A1762T/G1764A; M2, T1674G+T1753C+A1762T/G1764A; M3, C1653T+T1674G+A1762T/G1764A; and Ct-HBx, carboxylic acid-terminal truncated HBx) were delivered into Sleeping Beauty (SB) mouse models. The HCC incidence was higher in the M3-HBx- and Ct-HBx-injected SB mice. M3-HBx had a stronger capacity of upregulating inflammatory cytokines than other HBx variants. Ectopic expression of M3-HBx and Ct-HBx significantly increased proliferation and S phase proportion of HepG2 and HeLa cells, compared to WT-HBx. Plasminogen activator inhibitor-1 (PAI1) and cell division cycle 20 (CDC20) were identified as novel effectors by cDNA microarray analysis. M3-HBx and Ct-HBx significantly upregulated the expression of PAI1 and CDC20 in HepG2 and HeLa cells as well as the livers of SB mice. Silencing PAI1 attenuated the effects of M3-HBx and Ct-HBx on the growth of HepG2 and HeLa cells. PAI1, an important player bridging the HBx mutants and HCC, should be a promising candidate as a prognostic biomarker and therapeutic target in HBV-related HCC.