ABSTRACT
Interaction of human papilloma virus oncoproteins E6 and E7 with cell cycle proteins leads to disturbances of the cell cycle mechanism and subsequent alteration in the expression of some proteins, such as p16INK4a, cyclin D1, p53 and KI67. In this study, we compared alterations in the expression of these proteins during several stages of intraepithelial cervical carcinogenesis. Accordingly, an immunohistochemical study was performed on 50 cervical biopsies, including negative cases and intraepithelial neoplasias. The expression patterns of these markers were correlated with the histopathological diagnosis and infection with HPV. The p16INK4a, followed by Ki67, showed better correlation with cancer progression than p53 and cyclin D1, which recommends their use in the evaluation of cervical carcinogenesis. These monoclonal antibodies can be applied to cervical biopsy specimens to identify lesions transformed by oncogenic HPV, separating CIN 1 (p16INK4a positive) and identifying high-grade lesions by an increase in the cellular proliferation index (Ki67). In this way, we propose immunomarkers that can be applied in clinical practice to separate patients who need a conservative therapeutic approach from those who require a more aggressive treatment.
Subject(s)
Cell Cycle Proteins/metabolism , Uterine Cervical Dysplasia/metabolism , Uterine Cervical Neoplasms/metabolism , Adult , Aged , Aged, 80 and over , Biomarkers, Tumor/metabolism , Biopsy , Cell Proliferation , Cervix Uteri/anatomy & histology , Cervix Uteri/metabolism , Cyclin D1/metabolism , Cyclin-Dependent Kinase Inhibitor p16/metabolism , Female , Humans , Ki-67 Antigen/metabolism , Middle Aged , Tumor Suppressor Protein p53/metabolism , Uterine Cervical Neoplasms/pathology , Uterine Cervical Dysplasia/pathologyABSTRACT
An immunohistochemical analysis with monoclonal antibody p16(INK4a) was performed in formalin-fixed, paraffin-embedded samples of 60 cases. The aim was to investigate in biopsies the expression of p16(INK4a) of normal uterine cervical tissue, pre-cancerous and cancerous lesions, and their relation with human papilloma virus (HPV) and HIV status. Three parameters were evaluated: percentage of p16(INK4a) positive cells, reaction intensity, and cell staining pattern. All of these parameters were statistically different when compared among different histological groups. However, logistic regression model showed that the reaction intensity was the best indicator of the expression of p16(INK4a). This expression increases from normal to invasive squamous carcinoma. Sixty-six percent of the patients with CIN grade 1 (CIN1) expressed p16(INK4a) (all these cases were infected with high risk HPV). Our study supports the hypothesis that p16(INK4a) expression in pre-cancerous lesions and cancers can be used to identify HPV-transformed cells. Of great interest for routine diagnostic use is the fact that immunohistochemical testing for p16(INK4a) seems to be capable of identifying HPV-positive cells and potentially recognizing those lesions with an increased risk of progression to high-grade lesions.
