FAS ANTIGEN EXPRESSION AND ITS RELATIONSHIP WITH APOPTOSIS IN HUMAN HEPATOCELLULAR-CARCINOMA AND NONCANCEROUS TISSUES

Apoptosis, a programmed cell death, can be observed in the tissues of viral or autoimmune hepatitis and of hepatocellular carcinoma. Fas ant igen (Fas) was proposed as a protein that triggers apoptosis. To eluci date the relationship between Fas expression and its location in hepat ocellular carcinoma cells, we histochemically examined Fas expression by using 25 hepatocellular carcinoma tissues and their corresponding n oncancerous tissues, which were surgically obtained from the same pati ents. In addition, the relationship between Fas expression and apoptot ic cea numbers was examined in the hematoxylin-and-eosin-stained speci mens obtained from 23 of the 25 patients. Hepatocellular carcinoma tis sues expressed Fas less frequently and more weakly than noncancerous t issues. The majority of noncancerous specimens expressed Fas both on t he surface and in the cytoplasm, whereas the majority of hepatocellula r carcinoma expressed Fas only in the cytoplasm. Apoptotic cell counts were significantly higher in Fas-expressing tissues than in Fas-negat ive tissues. Among Fas-expressing tissues, the counts were higher in s urface Fas-expressing tissues than in tissues that expressed only cyto plasmic Fas (P < 0.01 to 0.05). Our findings indicate that the develop ment of apoptosis in hepatocellular carcinoma tissues relates to not o nly Fas expression but also its location.