p53 codon 72 polymorphism, loss of heterozygosity and high-risk human papillomavirus infection in a low-incidence German esophageal squamous cell carcinoma patient cohort

Abstract

Epidemiological studies in endemic geographic regions for esophageal squamous cell carcinoma (ESCC) suggested a number of risk factors, including modifications of the p53 tumor suppressor by codon Arg72Pro polymorphism, loss of heterozygosity (LOH) or human papillomavirus type 16 or 18 (HPV 16/18) infection. The p53 Arg72 variant has been suggested to be a high-risk factor in HPV-associated tumors. The present study analysed these associations in a low incidence geographic region in Germany. Fifty-three paraffin-embedded tumors and 53 surrounding normal squamous epithelium were investigated. For detection of p53 codon Arg72Pro polymorphism, direct sequencing for exon 4 was conducted. LOH analysis was performed using three microsatellite markers at the p53 gene locus, and all cases were screened for high-risk HPV infection (HPV 16 and 18) with primer specific PCR and confirmed by sequencing. The p53 codon 72 genotype distribution was identical to published studies of normal Caucasian population, suggesting no general influence of this polymorphism on esophageal cancer risk in Germany. One case showed a p53 mutation in exon 4. p53 LOH was found in 13/44 (30%) informative cases without any correlation to histopathological characteristics. Of 53 (17%) samples, 9 showed HPV 16 or 18 infection. We found no association between p53 codon 72 genotypes and increasing HPV infection rates. Interestingly, 8/9 HPV-positive cases showed at least one p53 Arg72 allele. These results indicate an important role of p53 in ESCC also in low-incidence regions. In combination with the p53 Arg72 variant HPV infection could contribute to the risk of ESCC development in these cases, as has been demonstrated for high-risk regions.