Apoptosis and Expression of bcl-2 Protein in Invasive DuctalAdenocarcinoma of the Pancreas

Overview

Apoptosis plays a central role in the development and/or progression of cancer. There are severalmethods for detection of apoptotic cells in tissue sections including light and electron microscopy,in situ nick end-labeling (ISEL), TdT-mediated dUTP nick-end labeling (TUNEL) and immunohistochemicaldetection of proteins associated with apoptosis. Apoptosis was assessed by the monoclonalantibody M30 CytoDEATH (M30), which is specific for neo-epitope in cytokeratin 18 thatbecomes available at an early caspase cleavage during apoptosis. Expression of bcl-2 protein wasevaluated, because bcl-2 protein plays an important role in the regulation of apoptosis. Twentysixinvasive ductal adenocarcinomas of the pancreas were studied immunohistochemically withantibodies M30 and bcl-2. The mean apoptotic index (AI, the percentage of apoptotic cells of thetotal tumor cells number) was 2.75%. High AI (>10%) was observed in 4 cases of the 26 pancreaticcarcinomas (15%). Protein bcl-2 was expressed in 3 cases (11,5 %). The AI did not correlate withthe expression of protein bcl-2. In conclusion, the detection of neo-epitope in cytokeratin 18 bymonoclonal antibody M30 can be used for quantification of apoptotic cells with immunohistochemicaltechniques in tissue sections. It is a new approach to evaluate apoptosis in pancreaticcarcinomas. The low positivity of bcl-2 expression in pancreatic adenocarcinomas suggests thatbcl-2 protein does not play a central role in pancreatic tumorigenesis and cancer progression.

Key words:
apoptosis – bcl-2 – pancreatic carcinoma – monoclonal antibody M30