Particular gene upregulation and p53 heterogeneous expression in -mutated maxillary carcinoma.

It has been demonstrated that tumor protein p53 () mutation in maxillary squamous cell carcinoma, is more treatment-resistant compared with the carcinoma without mutation. However, the association between mutation and treatment resistance remains unclear. As a first step in understanding the biological differences between tumors with and without mutation, a comprehensive gene expression analysis of maxillary squamous cell carcinoma with or without mutation was performed. A total of 42 genes were identified to be differentially expressed by >4-fold. Quantification of their mRNA using quantitative polymerase chain reaction indicated 18 genes with high expression and three genes with low expression in mutated tumors vs. wild-type tumors. The 18 genes included eight cell adhesion (, , and B) and four cell growth inhibition (, , and 3) genes. Among these genes, , , and , whose expression was markedly increased, also demonstrated high protein expression in immunohistochemical staining of mutated tumors. The mutated tumors demonstrated high nuclear staining of the TP53 protein only in tumor cells at the tumor margins adjacent to the stroma, whereas the tumor interior was negative for TP53. However, all tumor cells of wild-type tumors exhibited positive nuclear staining for the TP53 protein. The combined findings suggest that mutated tumors possess a phenotype opposite to that associated with cancer progression and malignant transformation, and exhibit tumor cell heterogeneity between the tumor interior and margins.