Expression of dominant negative p63 isoform in well-differenciated oral squamous cell carcinoma

The p53 which is well known as tumor suppressor gene is located at 17p13. p53 is a sequence-specific DNA binding transcription factor that responds to certain cytotoxic stresses, such as DNA damage, by enhancing the transcription of genes that regulate cell-cycle progression as well as programmed cell death. The p63 gene that is located at 3q27-29, is recognized members of the p53 family, and responsible for the transcription of 6 isoforms. Three isoforms (TAp63alpha, TAp63beta, TAp63gamma) contain an N-terminal transactivation (TA) domain and can induce apoptosis. The other 3 isoforms (deltaNp63alpha, deltaNp63beta, deltaNp63gamma) lack the TA domain and may function in a dominant-negative fashion by inhibiting the transactivation functions of p53 and TAp63 proteins, and thus act as oncoproteins. A number of studies have investigated the role of p63 in human squamous cell carcinomas from different organs. Only a few studies have examined deltaNp63 isoform in oral squamous cell carcinoma including normal epithelium. This study aimed to evaluate expression of deltaNp63 isoform in human oral squamous cell carcinoma tissue and normal mucosa. The 3 cases of well differenciated oral squamous cell carcinoma specimen including adjacent normal mucosa were examined, and immunohistochemical study with monoclonal antibody(4A4) and tumor cell apoptosis analysis with Transmission Electon Microscopy were studied. And, RT-PCR analysis was done for expression of deltaNp63 isoform. The results were as followed. 1. Normal gingiva showed the restricted p63 expression in basal cell layer. 2. Well differentiated squamous cell carcinoma showed mainly p63 expression in overall area of malignancy, especially in basal cell layer to adjacent stromal tissue. 3. Tumor cells around keratinized area with no p63 expression disclosed less micro-organelle in decreased size cytoplasm and severe chromatin margination with nuclear destruction that means apoptosis. 4. Comparison of mRNA expression of deltaNp63 isoform by RT-PCR showed variable expression of deltaNp63 isoform, but deltaNp63alpha was most highly expressed in all 3 tumor specimen. From theses results, it should be suggested that deltaNp63 isoform expression in well differentiated squamous cell carcinoma was closely related to tumor oncogenesis, expecially overexpression of deltaNp63alpha is a most important factor in tumor genesis of oral squamous cell carcinoma.

Expression of p63 and p73 Protein in Capillary Hemangioma / 中华皮肤科杂志

Objective To investigate the relationship between the expression of p63, p73 proteins and the development of hemangioma. Methods The immunohistochemical technique and quantitative image analysis were used to detect the expression of p63 and p73 proteins in 40 cases of capillary hemangioma and 20 specimens of normal skin. Results The absorbance value (mean ? SD) of p63 and p73 expression in normal skin tissue, proliferative phase of hemangioma and involuting phase of hemangioma were 0.923 ? 0.191 and 0.953 ? 0.120, 8.271 ? 1.953 and 6.408 ? 2.151, 0.920 ? 0.187 and 1.073 ? 0.516, respectively. The expression of p63 and p73 in proliferative phase of hemangioma was significantly increased as compared with those in involuting phase of hemangioma and normal skin tissue (P 0.05). Conclusions It is suggested that p63 gene is not a tumor suppressor gene but an oncogene in hemangioma and may contribute to the proliferation of endothelial cell and be associated with angiogenesis, and p73 may play an important role in the proliferation of hemangioma.