Proteomics Based Identification of Autotaxin As An Anti-Hepatitis B Virus Factor and a Promoter of Hepatoma Cell Invasion and Migration

Abstract

Background/Aims: Hepatitis B virus (HBV) infection is a major cause of cirrhosis and hepatocellular carcinoma. Therefore, we aimed to obtain further information on HBV pathogenesis, and to search for novel putative molecules for anti-HBV therapy. Methods: We utilized Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) to identify the secretory proteins that are differentially expressed in the HBV DNA-transfected HepG2.2.15 cell line and its parental HepG2 cell line. Immunohistochemistry (IHC) was employed to assess the clinical relevance of the observations. Small interfering (si)RNA-based silencing transfection methods were carried out to study the function of ENPP2. Results: Totally, 133 unique proteins were identified as differentially expressed in HepG2.2.15 cell line compared with HepG2 cell line. Ectonucleotide pyrophosphatase/phosphodiesterase family member 2 precursor (ENPP2) is one of the most significantly up-regulated secretory proteins associated with HBV replication. This differential expression of ENPP2 was further validated by real-time quantitative RT-PCR, Western Blot and immunohistochemical analysis. To study the function of ENPP2, we knockdown ENPP2 expression in HepG2.2.15 cell line by RNA interference. ENPP2 silencing increased HBV replication approximately 2.3-fold by enhancing, via the type I IFN signaling pathway, HBV cccDNA (covalently closed circular DNA) translation into viral RNA. Moreover, attenuation of ENPP2 expression inhibited both the invasion and migration ability of hepatoma cells in vitro via interacting with the molecules in the tumor microenvironment. Conclusion: Our study demonstrates that ENPP2 may be a novel anti-HBV target and indicate that suppression of its expression may inhibit the invasion and migration ability of hepatoma cells.

Hepatitis B Virus Promotes Hepatocellular Carcinoma Progression Synergistically With Hepatic Stellate Cells via Facilitating the Expression and Secretion of ENPP2

“…These mean antiviral treatments still act as key approaches to improve patient prognosis and could significantly decrease tumor recurrence and tumor-related death for HBV-related HCC patients. Increased ENPP2 expression is detected in chronic liver disease patients of different etiologies, including HBVassociated liver disease (Kaffe et al, 2017;She et al, 2018). The data from cancer databases confirmed that ENPP2 was highly expressed in HCC tissue compared within normal liver tissues, our clinical data displayed that HCC patients with high ENPP2 level normally had poor prognosis, and ENPP2 expression was positively correlated with HBV infection.…”

A rapid increase in lysophospholipids after geranylgeranoic acid treatment in human hepatoma-derived HuH-7 cells revealed by metabolomics analysis

“…In other words, if ENPP2 was suppressed by GGA, it could well explain GGA-induced increase in intracellular LPLs such as LPC(16:0), LPC(20:4), LPE(16:0), and LPE(20:4). Of note, ENPP2 expression has recently been considered to be very important in hepatoma development [ 25 ], including replication of hepatitis B virus [ 26 ] and hepatitis C virus [ 27 ]. Moreover, high ENPP2 expression in hepatoma is detected in patients with histological grade II/III [ 28 ].…”

The E3 Ubiquitin Ligase TRIM21 Promotes HBV DNA Polymerase Degradation

“…HBV infection causes serious liver diseases, including liver fibrosis, cirrhosis and hepatocellular carcinoma, which have a high mortality rate [40]. Elevated HBV DNA levels have been shown to be a powerful predictor of increased risk of liver fibrosis and liver cancer [41,42].…”