Comparative Analysis of Cluster of Differentiation 57 and Proliferating Cell Nuclear Antigen Expression in Different Grades of Oral Squamous Cell Carcinoma: An Immunohistochemical Study

Background: The immune defense against tumor cells is mainly mediated by the natural killer (NK) cells. Cluster of differentiation 57 (CD57) is a 110-kd glycoprotein, typically expressed by the NK cells, attacks the cancer cells and inhibits tumor development. Proliferating cell nuclear antigen (PCNA) is a 36-kd auxiliary protein for DNA polymerase delta that correlates with cell proliferation and DNA synthesis. It is an essential component of DNA replication, DNA recombination, and DNA repair. The uncoordinated proliferation of PCNA protein characterizes the biological behavior of malignant lesions. Aim: The aim of the present study is to compare and correlate the expression of CD57 and PCNA in different grades of oral squamous cell carcinoma (OSCC) by immunohistochemistry. Materials and methods: This retrospective analysis comprises 30 samples of various grades of OSCCs and 10 samples of healthy mucosa. Sections of 4-5 µm thickness were done and stained with monoclonal anti-PCNA and anti-CD57 antibodies. The statistical package for social science (SPSS) version 16.0 software (IBM Corp., Armonk, NY) was used to analyze the data in this study. The expression of CD57 and PCNA was compared and correlated between the groups using analysis of variance (ANOVA) post hoc, Dunnet t-test, and Pearson's correlation coefficient test. For statistical significance, a p-value of 0.05 or less was used. Results: A significant decrease in CD57 labeling index was seen from well-differentiated squamous cell carcinoma (16.63 ± 2.33) to poorly differentiated squamous cell carcinoma (5.53 ± 1.20) whereas the significant increase in PCNA labeling index was noted from well-differentiated squamous cell carcinoma (45.88 ± 2.20), followed by moderately differentiated and poorly differentiated squamous cell carcinoma (72.77 ± 4.35). Conclusion: The combination of CD57 and PCNA biomarkers appears to be good indicators of the immune status of the patient and the aggressiveness of the lesion.