Molecular analysis of p53 gene exon 7 codon 249 mutation in hepatocellular carcinoma patients presenting at Moi teaching and referral hospital, Kenya

Abstract

Hepatocellular carcinoma (HCC), a common type of liver cancer arising from progressive transformation of pre-cancerous dysplasia macronodules and hepatocytes is ranked as the fourth leading cause of death globally and a fifth cause of death in Africa. Several risk factors for HCC have been identified that include dietary and life style risks, significant genetic family history and predisposition to genetic mutation. It has been hypothesized that codon 249 of p53 gene is more susceptible to mutation induced by mutagenic and carcinogenic agents, increasing risk and/or progression of HCC. This study sought to identify mutation in codon 249 among HCC patients presenting with stage one cancer at Moi Teaching and Referral Hospital (MTRH), and to further determine the association of the mutation with the development of HCC. A total of forty six (46) archived blood samples for HCC patients and ten (10) controls were used in the study. DNA was extracted and purified from 200 uL aliquots of plasma and PCR amplified then sequenced using p53 exon 7 forward and reverse primers. Mutation detection and analysis were done using Molecular Evolutionary Genetics Analysis v.6.0 and ESPript v.3.0 softwares. The male to female ratio for both patients and controls was 1:1. The age range for HCC patients was from 25 to 67 years with a median of 42 years, and from 24 to 64 years with a median of 41 years for the controls. Guanine (G) - to - thymine (T) transversion in the third base of codon 249 of p53 gene was detected in plasma DNA from 8 of the 46 HCC patients and 1 of the 10 controls. There was no significant difference across gender among HCC subjects with and without mutation (p=0.4549) at 5% level of significance, however, there was a striking picture of significant existence of such mutation in a much older population in the HCC patients (p=<.0001) at 5% level of significance, suggesting that being in the old age is more susceptible to such mutation. There was no significant statistical association of codon 249 mutation between HCC patients and control (p=0.6821) at 5% level of significance. However, there was exaggerated increase in risk of acquiring codon 249 mutation among HCC patients (OR=0.5278: 95% CI 0.0584-4.7736). Consequently, although p53 gene codon 249 mutations has been found very minimal, its existence communicates a probable role in hepatocellular carcinogenesis. Nevertheless, the present study cannot exclude the possibility that mutation in codon 249 may act at later stages of hepatocellular carcinogenesis. This study warrants supplemental cross sectional and longitudinal studies, using larger sample sizes with higher number of HCC patients presenting with different stages to observe pattern across stages.