Identification of Programmed Cell Death (Apoptosis) and Cell Proliferation in Human Cholangiocarcinoma and Hepatocellular Carcinoma*

Vlad Herlea1, Liliana Pâslaru 2, Irinel Popescu 3

1. Department of Pathology. 2) Department of Biochemistry. 3) Department of Surgery and Liver Transplantation, Fundeni Clinical Institute, Bucharest

Abstract

In the liver, apoptosis has been observed mainly in cultured hepatocytes and hepatocellular carcinoma cell lines. In our study we used tissue samples from 9 intrahepatic peripheral cholangiocarcinomas – PCC, 6 hepatocellular carcinomas – HCC and 9 normal livers (all were from human). The mean age of studied subjects was 47 years in HCC and 54 years in PCC. Most of the studied tumors were of a moderate histological grade of differentiation (according to WHO). Most of them were single, nodular, tumoral masses with an average size of 10 cm in the largest diameter. For detection of apoptosis one of the serial sections from each paraffin block was subjected to the terminal deoxynucleotidyl transferase (TdT)- mediated deoxyuridine triphosphate (dUTP)- nick end-labeling TUNEL method. Proliferating cell nuclear antigen (PCNA) immunostaining was performed using streptavidin-biotin-peroxidase complex procedure. In each specimen of HCC, PCC and the normal liver (10 high power fields) the number of apoptotic and PCNA-positive cells was counted. The positive ratio of apoptotic cells was expressed as an apoptotic index (AI, percentage of apoptotic cells) and that of a PCNA-labeling index (PCNA-LI, percentage of PCNA –positive cells). The results are statistically significant (using the Mann-Whitney test). The conclusion of our study is that the percentage of apoptotic cells is significantly higher in PCC than in HCC, suggesting that the degree of apoptotic cell death is severe in PCC, but is relatively mild in HCC; also the apoptotic cells are consistently negative for PCNA and vice versa, suggesting that apoptotic cells do not show proliferative activity.

Key words

Apoptosis - cholangiocarcinoma - hepatocellular carci-noma - TUNEL method - proliferating cell nuclear antigen