HUMAN PAPILLOMAVIRUS INFECTION AND EXPRESSION OF P53 AND C-ERBB-2 PROTEIN IN LARYNGEAL PAPILLOMAS

Laryngeal papilloma (LP) is the most frequent benign laryngeal epithel ial tumor caused by human papillomaviruses (HPV) types 6 and 11. In th e present study, we were interested in whether we can find any prognos tic markers which might reflect the biological behavior of the coverin g epithelium in LP. We focused our attention on the determination of H PV infection, the detection of p53 protein, and c-erbB-2 protein in 24 biopsy specimens of LP. We confirmed the HPV 6 and 11 etiology in 23 of 24 LP. In these lesions the overexpression of p53 protein increased with the grade of epithelial abnormalities. The distribution of posit ive cells changed from scattered and focal, in simple and abnormal hyp erplasia. to diffuse in atypical hyperplasia. It has been shown that i n the presence of HPV types 6 and Il found in LP, p53 can still preser ve its tumor suppressor activity. Infection with HPV types 6 and ii mi ght therefore account for the significantly lower rate of malignant tr ansformation in LP. Two staining patterns for c-erbB-2 protein were ob served in the hyperplastic epithelium covering LP: membranous and cyto plasmic. With the increasing grade of epithelial abnormalities, cytopl asmic staining became predominant. and c-erbB-2 positivity sometimes o ccupied the whole epithelial thickness. This may represent either an a lteration in the processing stability of the c-erbB-2 mRNA, gene ampli fication, or even an artefact.