A novel HBx genotype serves as a preoperative predictor and fails to activate the JAK1/STATs pathway in hepatocellular carcinoma

J Hepatol. 2019 May;70(5):904-917. doi: 10.1016/j.jhep.2019.01.007. Epub 2019 Jan 14.

Abstract

Background & aims: Genetic variability in the hepatitis B virus X gene (HBx) is frequently observed and is associated with hepatocellular carcinoma (HCC) progression. However, a genotype classification based on the full-length HBx sequence and the impact of genotypes on hepatitis B virus (HBV)-related HCC prognosis remain unclear. We therefore aimed to perform this genotype classification and assess its clinical impact.

Methods: We classified the genotypes of the full-length HBx gene through sequencing and a cluster analysis of HBx DNA from a cohort of patients with HBV-related HCC, which served as the primary cohort (n = 284). Two independent HBV-related HCC cohorts, a validation cohort (n = 171) and a serum cohort (n = 168), were used to verify the results. Protein microarray assay analysis was performed to explore the underlying mechanism.

Results: In the primary cohort, the HBx DNA was classified into 3 genotypes: HBx-EHBH1, HBx-EHBH2, and HBx-EHBH3. HBx-EHBH2 (HBx-E2) indicated better recurrence-free survival and overall survival for patients with HCC. HBx-E2 was significantly correlated with the absence of liver cirrhosis, a small tumor size, a solitary tumor, complete encapsulation and Barcelona Clinic Liver Cancer (BCLC) stage A-0 tumors. Additionally, HBx-E2 served as a significant prognostic factor for patients with BCLC stage B HCC after hepatectomy. Mechanistically, HBx-E2 is unable to promote proliferation in HCC cells and normal hepatocytes. It also fails to activate the Janus kinase 1 (JAK1)/signal transducer and activator of transcription 3 (STAT3)/STAT5 pathway.

Conclusion: Our study identifies a novel HBx genotype that is unable to promote the proliferation of HCC cells and suggests a potential marker to preoperatively predict the prognosis of patients with BCLC stage B, HBV-associated, HCC.

Lay summary: We classified a novel genotype of the full-length hepatitis B virus X gene (HBx), HBx-E2. This genotype was identified in tumor and nontumor tissues from patients with hepatitis B virus-related hepatocellular carcinoma. HBx-E2 could preoperatively predict the prognosis of patients with intermediate stage hepatocellular carcinoma, after resection.

Keywords: BCLC staging; Cell proliferation; Genotype; HBx; Prognosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carcinoma, Hepatocellular / genetics*
  • Carcinoma, Hepatocellular / mortality
  • Carcinoma, Hepatocellular / pathology
  • Carcinoma, Hepatocellular / surgery
  • Cell Line, Tumor
  • Genotype
  • Humans
  • Janus Kinase 1 / physiology*
  • Liver Neoplasms / genetics*
  • Liver Neoplasms / mortality
  • Liver Neoplasms / pathology
  • Liver Neoplasms / surgery
  • Neoplasm Staging
  • Prognosis
  • STAT Transcription Factors / physiology*
  • Signal Transduction / physiology
  • Trans-Activators / blood
  • Trans-Activators / classification
  • Trans-Activators / genetics*
  • Viral Regulatory and Accessory Proteins / blood
  • Viral Regulatory and Accessory Proteins / classification
  • Viral Regulatory and Accessory Proteins / genetics*

Substances

  • STAT Transcription Factors
  • Trans-Activators
  • Viral Regulatory and Accessory Proteins
  • hepatitis B virus X protein
  • JAK1 protein, human
  • Janus Kinase 1