Expression of Bcl-2 in dysplastic and neoplastic cervical lesions in relation to cell proliferation and HPV infection

Expression of the bcl-2 gene has been shown to effectively confer resistance to programmed cell death in a variety of tumors. The bcl-2 proto-oncogene is involved in the development of human follicular lymphomas and also in a number of solid tumors such as carcinomas of prostate, breast, lung and GIT. The present study was designed to analyze the role of Bcl-2 expression in cervical intraepithelial squamous neoplasias (CIN) and cervical invasive carcinomas. Special attention was given to the association of Bcl-2 expression with the grade of the lesion, proliferative activity (expression of nuclear antigen of proliferative cells - PCNA) and human papillomavirus (HPV) DNA positivity. We examined tissue samples obtained from 86 women with varying degrees of cervical disease. Bcl-2 and PCNA were investigated using immunohistochemical staining and detection of HPV DNA was performed by hybridization in situ. Increased Bcl-2 expression was observed in advanced degrees of dysplasia and in carcinomas. We found a strong association between the presence of Bcl-2 in pathological epithelium with both the degree of dysplasia and the proliferative activity. We also observed a significant correlation between the amount of Bcl-2 positive lymphocytes infiltrating the lesions and the degree of disease. We, therefore, suggest that Bcl-2 expression in these lymphocytes may influence the antiviral or antitumor immune response. On the other hand we did not detect any significant correlation between the Bcl-2 oncoprotein and the presence of HPV. These results indicate that Bcl-2 may play an important role in the development of cervical cancer.