Abstract

The tumor suppressor gene protein 53 (p53) plays a general role in cell cycle control, the initiation of apoptosis and in DNA repair. The human p53 gene is mutated and accumulated in more than 50% of cancers. Codon 72 exon 4 polymorphism (Arg72Pro) of the p53 gene has been implicated in cancer risk. This study was aimed at investigating the possible association between p53 Arg72Pro polymorphism and susceptibility to breast cancer among Iranian population. The p53 Arg72Pro genotypes were determined by polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) analysis in 135 breast cancer cases and 150 controls. The PCR products were digested with BstU I restriction enzyme and the DNA fragments were then resolved by electrophoresis in 2% agarose gel. Out of the 135 breast cancer samples, 102 (75.55 %) samples were heterozygous (Arg/Pro), 27 (20%) samples homozygous for arginine (Arg/Arg) and 6 (4.45%) samples homozygous for proline (Pro/Pro). The frequencies of the three p53 genotypes; Arg/Pro, Arg/Arg and Pro/Pro in controls were 62, 24 and 14%, respectively. Heterozygosity for Arg/Pro of p53 codon 72 is potentially one of the genetic risk factors for breast cancer. The p53 Arg72Pro polymorphism may be used as a stratification marker in screening individuals at a high risk of breast cancer.

Key words: Breast cancer, protein 53 (p53), polymorphism, codon 72.