EXPRESSION OF P53 PROTEIN IN LARYNGEAL SQUAMOUS-CELL CARCINOMA AND DYSPLASIA - POSSIBLE CORRELATION WITH HUMAN PAPILLOMAVIRUS INFECTION ANDCLINICOPATHOLOGICAL FINDINGS

In order to evaluate the expression of p53 protein in 28 premalignant and 40 malignant squamous cell proliferations of the larynx and its re lationship to tobacco consumption, human papillomavirus infection and differentiation grade of the lesions, p53 expression was examined by m eans of a microwave post-fixation immunohistochemical method using the PAb 240 and PAb 1801 monoclonal antibodies. HPV infection was assesse d by non-isotopic in situ hybridization (NISH) and polymerase chain re action (PCR). A large proportion of carcinomas (77.5%) and dysplasias (61%) expressed p53. No difference was found between differentiation g rades of the lesions regarding p53 detection (P>0.1), but moderate or intense p53 expression was more frequent in the carcinomas (P<0.05). A statistical correlation was found between cigarette consumption and b oth p53 detection and p53 staining intensity (P<0.05 in each case). HP V study revealed HPV 16 and 18 infection only in carcinomas. The frequ ency was 28% and the physical state of the virus as demonstrated by NI SH was integration into the genome. We observed an inverse relationshi p between HPV infection and p53 expression (P=0.006). Our findings sug gest that p53 overexpression is a common and early event which increas es in frequency with progression of laryngeal squamous cell carcinoma. The expression of p53 is influenced by tobacco and high-risk types of HPV.