Expression of P53 in Oral Squamous Cell Carcinoma - an IHC Study; Deep Insight into P53

Background: Oral squamous cell carcinoma (OSCC) entails quite noteworthy morbidity and mortality rates instead of immense amount of research and advances. Mutation in the TP53 gene is the most common genetic change found in oral squamous cell carcinoma (OSCC). Once activated, the p53 protein can induce the growth arrest, as well as cell death. Mutation and subsequent inactivation of a tumor suppressor gene causes 'loss of function'. This can damage its deoxyribonucleic acid (DNA) binding properties and transcription factor function, thus, inhibiting its normal function in cell cycle control and in cell proliferation. Aim: A comparative study of P53 expression in oral squamous cell carcinoma using immunohistochemical techniques. Materials and Methods: To study the relationship between histological grades of oral squamous cell carcinoma and P53 protein expression and also to compare along with normal mucosa, a total of 40 cases of histologically diagnosed OSCC were considered for the study group and 10 paraffin embedded normal mucosal tissue blocks were collected. The analysis of p53 positive cells was performed on IHC stained sections. Only staining of nucleus of epithelial cells was observed. Nuclei with clear brown colour regardless of staining intensity were considered as p53 positive. Counting of cells was done with graticule eyepiece. All these cases were reviewed and classified according to modified Anneroths histological malignancy grading system. Results: When p53 expression was compared between the two groups i.e control and study groups. The expression of p53 was nil in normal oral mucosal tissue (control), while study group i.e OSCC expressed about 47.49% with Std.Dev of +/- 35.83%. And it was found to be a statistically significant (p<0.001). Conclusion: The present study concludes a positive correlation between the histopathological grades of OSCC and immunohistochemistry (p53 expression). Expression of p53 above the basal layer is an early event in oral carcinogenesis and an indicator of a developing carcinoma preceding morphological tissue alterations. However, since immunohistochemistry cannot always detect changes in p53 expression in premalignant/malignant lesions, it is strongly recommended that p53 immunohistochemistry be used in conjugation with routine histology to increase the sensitivity of detection of cases that eventually progress to malignancy.