Analysis of TP53 Codon 72 Polymorphism in Mucinous and Non-Mucinous Colorectal Adenocarcinoma in Isfahan, Iran

Background: The tumor suppressor gene TP53 (alias p53) located on chromosome 17 is involved in various cancers. Case-control studies have shown that p53 codon 72 polymorphism modulates the prognosis and susceptibility to various malignancies. We undertook the present study to explore a possible association between mucinous and non-mucinous adenocarcinomas with different genotypes or alleles at codon 72 of TP53. Methods: The genotype distribution and allelic frequencies for p53 polymorphism was assessed in 46 and 134 specimens from patients with colorectal mucinous and non-mucinous adenocarcinomas, respectively, by using allele-specific PCR. Results: The PCR products were 177bp for proline allele and 141bp for arginine allele. In the mucinous samples, the genotype distribution for p53 polymorphism showed 63%, 23.9%, and 13.1% for the Arg/Arg, Arg/Pro, and Pro/Pro genotypes, respectively. In the non-mucinous specimens 32.1% of the cases were Arg/Arg, 48.5% Arg/Pro, and 19.4% pro/pro. A significant difference between the two types of adenocarcinomas for the Arg 72 Arg genotype compared with (grouped) Arg 72 Arg and Pro 72 Pro genotypes was noted [OR=3.61 (1.76-7.27), P<0.001]. The arginine allele was found more often in patients with mucinous adenocarcinoma [OR=1.85 (1.07-3.19), P<0.03]. A higher portion of Dukes stage C was noted in the mucinous specimens (P<0.02) and also mucinous specimens were seen more often at advanced TNM stages (P=0.01). Conclusion: The Arg/Arg genotype at p53 codon 72 is more prevalent in mucinous colorectal carcinoma and the arginine allele may contribute to mucinous carcinogenesis. The proline allele was associated with higher Duke's staging in non-mucinous adenocarcinoma.