Death-Associated Protein Kinase is Underexpressed in High-Grade Oral Squamous Cell Carcinoma

An immunohistochemical analysis of 40 cases of oral squamous cell carcinoma was performed to evaluate the relationship between the expression pattern of death-associated protein kinase (DAPk) positive cells with the histological malignancy grading of these lesions. According to our results, eleven cases (27.5%) were high-grade malignancy tumours and 29 (72.5%) were low-grade ones. We found that 92.86% of the low-grade tumours were positive to anti-DAP kinase antibody whereas only 7.14% of the high-grade tumours presented positivity, and this difference was statistically significant (p<0.01). Sixteen (55.2%) of the low-grade carcinomas exhibited moderate immunoreactivity whereas ten cases (34.5%) showed weak staining and three cases (10.3%) were negative tumours. Immunostaining was lacking in nine (81.8%) of the high-grade carcinomas and "weak" in the two (18.2%) remaining cases. Thus, DAPk expression is significantly decreased in high-grade oral carcinomas, and evidences indicate that it might be related to the severity of cytological atypia.