p53 protein expression in benign lesions of the upper respiratory tract

p53 is a tumor suppressor gene that is lost or mutated in most forms of human malignancy. There are, however, very few studies evaluating p53 expression in normal epithelium or benign lesions.

We screened for p53 protein expression in a variety of benign epithelial lesions of upper respiratory tract using monoclonal antibody DO-1 on paraffin-embedded material.

We studied a total of 109 cases: 16 cases of juvenile and 36 cases of adult laryngeal papillomatosis, 10 cases each of laryngeal nodules and laryngeal polyps, 17 cases of inverted papilloma, and 20 cases of nasal polyps.

Nuclear immunoreactivity for p53 protein was demonstrated in 14 (88%) of 16 cases of juvenile laryngeal papillomatosis, 33 (92%) of 36 cases of adult laryngeal papillomatosis, 4 (40%) of 10 cases of laryngeal nodules, 8 (80%) of 10 cases of laryngeal polyps, 7 (41%) of 17 cases of inverted papilloma, and 2 (10%) of 20 cases of nasal polyps. These results pertained only to the basal epithelial layer in all cases of laryngeal nodules, laryngeal polyps, and nasal polyps. Intermediate layer cells were also positive for p53 in the majority of the cases of both juvenile (69%) and adult (75%) laryngeal papillomatosis and in a minority of the cases of inverted papilloma (18%).

Overexpression of p53 protein is commonly demonstrable in benign epithelial lesions of the upper respiratory tract. This observation suggests that p53 protein accumulation may occur in the absence of mutation of the p53 gene and may correlate with epithelial proliferative activity.