P53 Codon 72 Gene Polymorphism Studies and p53 Expression by IHC in Oral Lesions as Risk Factor for Malignancy

Abstract

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 HPV infection. In India, instead of HPV, tobacco/pan masala chewing are more commonly associated with oral cancer, hence the present study was planned. Materials and Methods: A total of 41 cases of oral lesions comprising 6 cases of leukoplakia and 35 cases of oral SCC, between 30-60 years age, and were tobacco/pan masala chewers were taken. Analysis of p53 codon 72 gene polymorphism was performed by PCR - RFLP 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 6 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 4 cases (11.42%) showed negative staining. Among 6 cases of Leukoplakia, 3(50%) showed weak staining and 3(50%) showed negative results. Conclusion: The findings of the present study indicate that there is no significant association between P53 codon 72 gene polymorphism and p53 expression by IHC with OSCC and Leukoplakia, associated with tobacco/ pan-masala chewing.