Ser-249 TP53 and CTNNB1 mutations in circulating free DNA of Egyptian patients with hepatocellular carcinoma versus chronic liver diseases.

Circulating free DNA (CFDNA) has been shown to be a good source of liver tissue-derived DNA in African and Asian patients with chronic liver disease or HCC. In Egypt, HCC is a frequent carcinoma and mostly occur in the context of chronic infection by HCV, a widespread infection in the Egyptian population. Here we have examined the presence of mutations in TP53 at codon 249 (Ser-249, considered as a hallmark of mutagenesis by aflatoxin) and in CTNNB1 (gene encoding beta-catenin) in CFDNA of patients with HCC or chronic liver disease, from Alexandria, Egypt. The DNA concentrations were significantly higher in HCC patients compared to HBV and HCV carriers without cancer, and to sero-negative individuals. Ser-249 TP53 mutations were determined using PCR-restriction digestion (RFLP) in CFDNA of 255 subjects, and confirmed by sequencing. Ser-249 was found in CFDNA of 12 subjects (4.8%), with the highest prevalence in subjects with chronic liver disease and infection by HBV (6/36; 16.7%) Mutations in CTNNB1 were examined using PCR combined to DHPLC and followed by sequencing. No mutations were found in CTNNB1 neither in CFDNA or in tumour tissue. In parallel, studies on DNA extracted from 20 HCC biopsies showed the presence of ser-249 mutation in two cases (10%). These results indicate that mutagenesis by aflatoxin may play a role in hepatocarcinogenesis in Egypt, and CFDNA may serve as a convenient source of material in monitoring the effects of aflatoxin exposure and viral infections in chronic liver disease and cancer.