P53 codon 72 polymorphism and susceptibility to development of human papilloma virus-associated cervical cancer in Indian women

BACKGROUND: Infection with human papilloma virus (HPV) is an important etiological factor in the development of cervical cancer and it has been proposed that individuals homozygous for Arg/Arg at codon-72 of p53 are seven times more susceptible to HPV-mediated cancer. In this study, we have analyzed the genetic predisposition of the India population to HPV infection and cervical carcinogenesis. METHODS: We investigated 71 cases of squamous cell carcinoma of the cervix, 14 cases of low-grade squamous intraepithelial lesions, 25 cases of high-grade squamous intraepithelial lesions and 29 noncancer controls for presence of HPV16/18 infections by L-1-specific PCR assay and Southern hybridization, and its association with polymorphism at p53 codon 72. RESULTS: We observed that 69.1% (76/110) of the cervical cancer patients were HPV positive, among which the presence of HPV16, 18 and 16/18 coinfection was 40.9%, 8.2% and 13.6%, respectively. The allele frequencies of the three p53 genotypes Arg/Arg, Arg/Pro and Pro/Pro in the HPV-positive tumour samples were 0.34, 0.57 and 0.09 in comparison with frequencies of 0.18, 0.44 and 0.38 for HPV-negative tumours. Hence, there is a significant difference in the allelic frequency of p53 Arg/Arg in high-risk HPV-infected cervical carcinoma cases (0.34) and HPV-negative carcinomas (0.18). CONCLUSION: Our results indicate a striking over-representation of homozygous arginine at codon 72 of p53 in HPV-associated cervical carcinogenesis. We conclude that women with Arg/Arg homozygous allele are more prone to infection by HPV16/18, which leads to cervical carcinomas having poor prognosis.