P16 Protein and Human Papillomavirus (HPV16, 18) Expressions in Oral Lichen Planus and Squamous Cell Carcinoma


Background: Oral carcinogenesis is a molecular and histological multistage process featuring genetic andphenotypic markers for each stage, which involves enhanced function of several oncogenes and/or thedeactivation of tumor suppressor genes, resulting in the loss of cell cycle checkpoints. The progression towardsmalignancy includes sequential histopathological alterations ranging from hyperplasia through dysplasia tocarcinoma in situ and invasive carcinoma. The p16 gene produces p16 protein, which in turn inhibits phosphorylationof retinoblastoma, p16 play a significant role in early carcinogenesis. Human papillomavirus is a well establishedheterogeneous virus and plays an important role in oral cancers. The aims of the study were to evaluate, compareand correlate the immunohistochemical expression of p16 protein and HPV16/18 with each other in oral lichenplanus and oral squamous cell carcinoma, and with various clinicopathological findings.Materials and methods: Forty formalin-fixed, paraffin embedded tissue blocks (24 cases of oral lichen planus, and 16cases of oral squamous cell carcinoma) were included in this study, an immunohistochemical staining wasperformed using anti p16 monoclonal antibody, and anti HPV16/18 monoclonal antibodies.Results: Positive IHC expression of p16 was found in 11 cases (68.75%) of OSCC, and in 19 cases (79.166%) of OLP.Positive IHC expression of HPV16 was found in 2 cases (12.5%) of OSCC, and in 1 case (4.16%) of OLP. IHC expressionof HPV18 showed negative expression in all cases of OSCC, and found only in 1 case (4.16%) of OLP.Conclusions: This study signifies the statistically non significant correlation between p16 and HPV 16/18 in OLP andOSCC