Expression of p53 in normal nasal mucosa and in sinonasal papillomas with and without associated carcinoma and the relation to human papillomavirus (HPV) Maria-B. Franzmann a, *, Christian Buchwald b , Grete Krag Jacobsen a , Henning Lindeberg c a Institute of Pathology, Gentofte University Hospital, Fred. V vej 11, Gentofte, DK-2100, Denmark b Department of Otolaryngology, Rigshospitalet, Copenhagen, Denmark c Department of Maxillo-Facial Surgery and Oral Pathology, Royal Dental College, Aarhus, Denmark Received 9 October 1997; received in revised form 17 February 1998; accepted 17 February 1998 Abstract The aim of the present study was to investigate the expression of p53 in sinonasal papillomas, carcinomas ex papillomas and normal nasal mucosa. Furthermore, we wanted to study the expression of p53 in relation to the presence of human papilloma virus (HPV). Immunohistochemical staining was performed on 37 formalin-fixed paraffin-embedded biopsies comprising seven biopsies from normal nasal mucosa, 13 papillomas of an exophytic growth pattern, 12 papillomas of an endophytic growth pattern and five carcinomas. The level of p53 overexpression was defined as more than 5% positive nuclei. The normal nasal mucosa showed no positive nuclei. The papillomas of both exophytic and endophytic growth patterns showed scattered positive nuclei, but in all cases this was less than 5%. p53 was overexpressed in three out of five carcinomas. In conclusion, we found an overexpression of p53 in carcinomas occurring in sinonasal papillomas but not in the benign tumours of the sinonasal mucosa. Thus, this report supports the concept that p53 may have a role in the carcinogenic process in head and neck tumours.  1998 Elsevier Science Ireland Ltd. All rights reserved Keywords: Sinonasal papillomas; Carcinomas; p53; Human papilloma virus 1. Introduction The p53 gene is a tumour suppressor gene that is localized on the short arm of chromosome 17. The gene encodes a 393 amino acid nuclear phosphopro- tein [1–7]. p53 functions as a tumour suppressor by starting a protective cell cycle arrest and by initiating an apoptotic response in DNA-damaged cells [8– 10]. Mutations in the p53 gene are known as one of the most common specific genetic changes found in human cancers. The expression of p53 has been inves- tigated in a great number of malignant lesions, i.e. lung, breast, liver and colon, as well as in oral and laryngeal carcinomas, but to our knowledge not yet in nasal lesions. The wild-type p53 has a fast turnover time of about 20 min and is therefore usually not Cancer Letters 128 (1998) 161–164 0304-3835/98/$19.00  1998 Elsevier Science Ireland Ltd. All rights reserved PII S0304-3835(98)00058-5 * Corresponding author.