Differential expression of p63 isotypes (ΔN and TA) in salivary gland neoplasms: Biological and diagnostic implications

To determine the association between the expression of p63 gene isoforms (TA and ΔN) and salivary gland tumorigenesis, we performed reverse transcription-polymerase chain reaction analysis of these markers in 71 benign and malignant salivary gland neoplasms. The results were correlated with the expression of Notch ligand JAG1 gene and the clinicopathologic features and the full-length p63 protein expression by immunohistochemistry. Both p63 isoforms were either negative or weakly expressed in normal salivary gland tissues. TAp63 was highly expressed in most benign tumors and was either negative or weakly positive in most carcinomas. Conversely, ΔNp63 was negative or faintly positive in most benign neoplasms and was highly expressed in adenoid cystic, mucoepidermoid, and myoepithelial carcinomas. Immunohistochemical analysis using anti-full-length p63 protein showed ubiquitous nuclear staining in basal and myoepithelial cells in both benign and malignant neoplasms. JAG1 was expressed in most benign and malignant tumors and did not correlate with p63 isoforms expression. We conclude that (1) p63 isoforms are differentially expressed in most benign and malignant tumors and may play distinct biological roles in certain salivary gland neoplasms; (2) p63 immunostaining do not correlate with the isoforms expression; and (3) isoform-specific antibodies are required for better cellular localization and biological correlations.