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.