TP53 Mutations and HBX Status Analysis in Hepatocellular Carcinomas from Iran: Evidence for Lack of Association between HBV Genotype D and TP53 R249S Mutations

Abstract

High incidence of HCC is mostly due to the combination of two major risk factors, chronic infection with hepatitis B (HBV) and/or C (HCV) viruses and exposure to the mycotoxin aflatoxin B(1), which induces a particular mutation at codon 249 in TP53 (R249S). Eight genotypes of HBV are diversely found in high and low incidence areas. Regardless of documented strong associations between TP53 R249S mutation and HBV genotypes B, C, A or E, there is no report of such association for genotype D despite of the presence of aflatoxin in areas with high prevalence of HBV genotype D. In Iran, 3% of the population is chronically infected with HBV, predominantly genotype D. Twenty-one histologically confirmed HCC cases from Iran were analyzed for TP53 R249S and HBV double mutations 1762(T)/1764(A), hallmarks of more pathogenic forms of HBV. We did not detect any of these mutations. In addition, we report the only case identified so far carrying both R249S mutation and chronic HBV genotype D, a patient from The Gambia in West Africa. This paper suggests that association between HBV genotype D and aflatoxin-induced TP53 mutation is uncommon, explaining the relatively lower incidence of HCC in areas where genotype D is highly prevalent.

Figure 1

Number of mutations along of HBx amino acids. Mutation analysis was performed using alignment with GenBank HBV references by MEGA5 software [23]. Four main mutation points were amino acids 30, 78, 101, and 116.

Figure 2

Neighbor-joining phylogenetic analysis using HBS gene of genotype D. The four subgenotypes D1 to D4 sequences were extracted from GenBank. The HCC R249S positive case from the case-control study from The Gambia is shown by an orange arrow and corresponds to subgenotype D1 (green circle). Made by the software MEGA5 [23].