Novel natural mutations in the hepatitis B virus reverse transcriptase domain associated with hepatocellular carcinoma

Abstract

Background/aim: Hepatitis B Virus (HBV) mutations play a role in the development of hepatocellular carcinoma (HCC). However, the association between HBV polymerase gene mutations and HCC has not been reported. In this study, we conducted a multi-stage study to identify HCC-related mutations in the reverse transcriptase (RT) domain of the HBV polymerase gene.

Methods: A total of 231 HCCs and 237 non-HCC controls from Qidong, China, were included in this study. The entire sequence of HBV RT was first compared between 29 HCC and 35 non-HCC cases, and candidate mutations were then evaluated in two independent validation sets.

Results: There were 15 candidate mutations identified from the discovery set, with A799G and T1055A being consistently associated with HCC across all studies. A pooled analysis of samples revealed that A799G, A987G, and T1055A were independent risk factors for HCC, with adjusted odds ratios of 5.53 [95% confidence interval (CI), 1.69-18.10], 4.20 (95%CI, 1.15-15.35), and 3.78 (95%CI, 1.45-9.86), respectively. A longitudinal study showed that these mutations were detectable 4-5 years prior to HCC diagnosis.

Conclusions: Our study provides evidence the first that HBV RT contains naturally occurring mutations that can be used as predictive markers for HCC.

Figure 1. Study design.

Abbreviations: HCC, hepatocellular carcinoma; PCR, polymerase chain reaction; RT, reverse transcriptase.

Figure 2. Frequency of nucleotide mutations and amino acid substitutions within HBV RT domain (n = 64).

The values are presented as the percent nucleotide mutations (upper panel) or amino acid substitution (lower panel) compared to the wild-type genotype C hepatitis B virus (HBV) DNA sequence. The locations of the domains (A–F) are shown at the top of the figure. The pre-S/S-overlapping region in the polymerase gene is identified by grey areas. Abbreviation: HBV, hepatitis B virus; RT, reverse transcriptase.

Figure 3. Effects of the A799G and T1055A mutations on circulating HBV DNA levels in all participants.

The effects of the mutations A799G and T1055A on circulating HBV DNA load were estimated using blood samples from a total of 468 participants (HCC patients or non-HCC controls). Among these participants, 47 (10.0%) harbored A799G and 48 (10.3%) harbored T1055A. Circulating hepatitis B virus (HBV) DNA level was determined by quantitative real-time PCR. The data represent the mean ± SE. *, P<0.050.