Correlation with Grade of Cervical Neoplasia with Apoptosis Detected by in Situ Nuclear Labeling

Kim, J H; Ko, C W; Heh, J R; Na, J H; Kim, Y M; Kim, Y T; Nam, C H; Mok, J E

Abstract

Invasive cervical cancer is thought to arise from the progression of precancerous lesions. The fact that spontaneous regression frequently occurs in low-grade lesions but a part of high-grade lesions progresses to invasive carcinoma suggests that selection of a cell population with high malignant potential may be closely linked to progression of cervical neoplasia. The rate of cell accumulation is determined by the balance of cell proliferation and cell death. Apoptosis (programmed cell death) is an important mechanism of cell loss in tissue modelling with apparent differences from necrosis, and associated with the progression of neoplasia. Therefore in order to better understand the development of cervical neoplasia, we investigated the rate of apoptosis according to the grade of cervical neoplasia. Archival cervical tissue samples from normal epithelium (n=10), low-grade squamous intraepithelial lesions (LSIL, n=20), high-grade squamous intraepithelial lesions (HSIL, n=20), and squamous cell carcinoma (SCC, n=10) were evaluated for chromatin cleavage, a hallmark of programmed cell death. We used in situ end-labelling of DNA strand breaks by terminal deoxynucleotidyltransferase (TdT) incorporation of heteropolymer of digoxigenin-11 -dUTP and dATP to 3`-OH ends of DNA, identified by anti-digoxigenin-peroxidase. Apoptotic bodies were identified as whole cells containing intact nuclei stained, often with peripheral chromatin clumping. To quantitate differences in the rate of labelling, apoptosis was expressed as an apoptotic index [AI=(sum of apoptotic bodies/total epithelial nuclei)x100]. The apoptotic index (AI) significantly increased (p<0.001) as the grade of cervical neoplasia increased: 0.06+/-0.02% (mean+/-S.D.) in normal cervical epithelium, 0.17+/-0.05% in LSIL, 1.44+/-0.93% in HSIL, and 3.54+/-0.79% in squamous cell carcinomas. These data suggest that the progression of neoplasia in the uterine cervix is accompanied by increased cellular deletion. The significant correlation of AI with lesion grade sugges.