IMMUNOHISTOCHEMICAL DETECTION OF PROLIFERATING CELL NUCLEAR ANTIGEN IN HEPATOCELLULAR-CARCINOMA - RELATIONSHIP TO HISTOLOGICAL GRADE

Proliferating cell nuclear antigen (PCNA), also known as cyclin, is an auxiliary protein of DNA polymerase-delta and is found only in the nu clei of proliferating cells in the late G1 and S phases. The prolifera tion of hepatocellular carcinoma (HCC) by immunohistochemical staining for PCNA using paraffin sections of 20 surgically resected HCC specim ens was analysed. The mean percentage of PCNA-positive nuclei in the H CC tissue was 10.3% in grade I of Edmondson and Steiner's classificati on, 25.5% in grade II, 28.4% in grade III and 41.5% in grade IV. In ea rly HCC, we observed only a few PCNA-positive tumour cells. However, P CNA-positive nuclei were numerous in the tumour thrombi found in porta l vein branches, in regions of extracapsular tumour growth, and in the inner nodules of tumours with a nodule-in-nodule formation. Prolifera ting cell nuclear antigen positivity was correlated with an increase o f the nucleocytoplasmic ratio of tumour cells as determined by image a nalysis. Our findings showed that PCNA positivity was correlated with the histological grade and invasiveness of HCC, suggesting that this a ntigen may be used as an indicator to predict tumour invasion in patie nts with HCC.