Frequency of p53 gene mutation and protein expression in oral squamous cell carcinoma.

OBJECTIVE To determine the frequency of p53 gene mutation and protein expression in Oral Squamous Cell Carcinoma (OSCC) and to establish correlation between the two. STUDY DESIGN Analytical study. PLACE AND DURATION OF STUDY Histopathology Department and Molecular Biology Laboratory, Armed Forces Institute of Pathology (AFIP), Rawalpindi, from May 2010 to May 2011. METHODOLOGY Thirty diagnosed cases of OSCC were selected by consecutive sampling. Seventeen were retrieved from the record files of the AFIP, and 13 fresh/frozen sections were selected from patients reporting to the Oral Surgery Department, Armed Forces Institute of Dentistry (AFID). Gene p53 mutation was analyzed in all the cases using PCRSSCP analysis. DNA was extracted from the formalin-fixed and paraffin-embedded tissue sections and fresh/frozen sections. DNA thus extracted was amplified by polymerase chain reaction. The amplified products were denatured and finally analyzed by gel electrophoresis. Gene mutation was detected as electrophoretic mobility shift. The immunohistochemical marker p53 was applied to the same 30 cases and overexpression of protein p53 was recorded. RESULTS Immunohistochemical expression of marker p53 was positive in 67% [95% Confidence Interval (CI) 48.7-80.9] of the cases. Mutations of the p53 gene were detected in 23% (95% CI 11.5-41.2) of the OSCC. No statistically significant correlation was found between p53 gene mutation and protein p53 expression (rs=-0.057, p=0.765). CONCLUSION A substantial number of patients have p53 gene mutation (23%) and protein p53 expression (67%) in oral squamous cell carcinoma (OSCC).