Detection of apoptotic cells in human colorectal cancer by two different in situ methods: Antibody against single-stranded DNA and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) methods

We comparatively investigated the extent of apoptotic cell loss in human co lorectal cancers evaluated by two methods, namely the conventional terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUT P)-biotin nick end-labeling (TUNEL) method and immunohistochemistry for sin gle-stranded (ss) DNA. The apoptotic index (AI) obtained with the TUNEL met hod was higher than that shown by the immunohistochemistry for ssDNA. Howev er, a significant correlation in AIs evaluated by these methods was found. The AIs obtained by both methods were significantly higher in the advanced canters than in the early cancers. Cellular proliferation activity was asse ssed in terms of positivity rate (PR) for expression of proliferating cell nuclear antigen (PCNA). The PR of advanced canters was significantly higher than that of early cancers. The present results indicate that immunohistoc hemistry for ssDNA is useful (as is the TUNEL method) for evaluation of apo ptotic tumor cells in colorectal carcinomas. In addition, it was confirmed that there is a remarkable increase of not only proliferation activity, but also tumor cell apoptosis in the process of progression of colon canter fr om early to advanced stages of the disease.