Immunohistochemical expression of p16 and HPV L1 capsid proteins as predictive markers in cervical lesions

Abstract

Human papilloma virus (HPV) infection is the most important cause of cervical cancer, but only 2 % of cervical HPV infections will develop into cervical cancer. p16 INK4A has been introduced as a marker for HPV infection in cervix. HPV L1 capsid protein is also known to be associated with the productive phase of HPV infection; however, expression pattern in different HPV-associated cervical lesion and its correlation to p16 expression is not still well understood. The authors aimed to elucidate the relationship between L1 and p16 expression in cervical lesions. Immunohistochemical studies using antibodies against L1 capsid and P16 proteins were carried out on 89 paraffin-embedded tissue samples including 11 low-grade cervical intraepithelial neoplasias (CIN), 11 high-grade CINs, 20 cervical squamous cell carcinomas (SCC), eight cervical adenocarcinomas and 39 normal cervical tissues as a control group. L1 capsid protein was positive in 63.6 % of low-grade CINs and 9.1 % of high-grade CINs; while none of the cervical SCCs, adenocarcinomas or normal cervical tissues showed this marker. In contrast, p16 protein was positive in 81.8 % of low-grade CINs, 90.1 % of high-grade CINs, 90 % of SCCs, 75 % of adenocarcinomas and 10.25 % of normal cervical tissues (p value < 0.001). Despite the presence of interobserver variation in the histopathologic interpretation of cervical lesions, in more instances definite diagnosis is made by routine histopathological examination and these ancillary tests are supportive in follow-up of the patient.