p53 Codon 72 Gene Polymorphism Studies and p53 Expression by Immunohistochemistry in Oral Lesions as Risk Factor for Malignancy.

BACKGROUND

Wild-type p53 nuclear phosphoproteins are critical cell cycle regulatory tumor-suppressor gene. Genetic mutation of p53 gene is common in several head-neck cancers, usually associated with smoking and human papillomavirus (HPV) infection. In India, instead of HPV, tobacco/pan masala chewing is more commonly associated with oral cancer.

AIM

The aim of this study was to investigate p53 codon 72 gene polymorphism and expression of p53 by immunohistochemistry (IHC) in oral lesions as a risk factor for its association with malignancy.

MATERIALS AND METHODS

A total of 41 cases of oral lesions comprising 6 cases of leukoplakia and 35 cases of oral squamous cell carcinoma (OSCC), between 30 and 60 years age and tobacco/pan masala chewers were taken. Molecular analysis of p53 codon 72 gene polymorphism was performed by polymerase chain reaction - restriction fragment length polymorphism for Arg/Arg, Arg/Pro, and Pro/Pro. Tissue expression of p53 was done by IHC.

RESULTS

Genotype frequencies of 35 carcinoma cases of p53 Arg/Arg, Arg/Pro, and Pro/Pro were 23%, 57%, and 20%, respectively, and six leukoplakia cases of p53 Arg/Arg and Arg/Pro genotype were 50% and 50%, respectively. By IHC for expression of p53 out of 35 cases of OSCC biopsies, 17 (48.57%) had weak staining, 14 cases (40%) showed evidence of p53 protein staining, and four cases (11.42%) showed negative staining. Among six cases of leukoplakia, 3 (50%) showed weak staining and 3 (50%) showed negative results.

CONCLUSION

The findings of the study indicate that there is no significant association between p53 codon 72 gene polymorphism with OSCC and leukoplakia associated with tobacco/pan masala chewing.