Serum alkaline-stable acid thiol proteinase--a possible marker for primary liver carcinoma

Activities of alkaline phosphatase (ALP), gamma-glutamyl transferase (GMT), lactate dehydrogenase (LD), beta-glucuronidase (GLU) and cathepsin B-like (CB-like) were determined in blind-coded sera from 50 patients with primary liver carcinoma, liver cirrhosis and acute hepatitis, and from 40 control subjects of comparable age range. CB-like activity averaged 700% (p less than 0.01), 1590% (p less than 0.01) and 1600% (p less than 0.01) of control subjects in liver cirrhosis (n = 30), acute hepatitis (n = 5) and primary liver carcinoma (n = 15), respectively. In acute hepatitis group we have found significant correlation between CB-like and GLU activities (r greater than 0.95). This correlation, however, was not observed in primary liver carcinoma suggesting that alteration in CB-like activity is not due to generalized increases in lysosomal membrane instability. The primary liver carcinoma group exhibited also the modest increments in serum ALP, GMT and LD activities (p less than 0.01). This increment, however, was not detected in any of acute hepatitis or liver cirrhosis patients. For the first time the alkaline-stable form of CB-like in human serum is described. This form representing 40% of overall CB-like activity was present in all primary liver carcinoma patients. This form, however, was not present in sera of any of control subjects or in sera of patients with acute hepatitis and liver cirrhosis with the exception of two men, in whom we have probably dealing with an early stage of primary liver carcinoma. Although the nature of the increment in CB-like activity in cancer remains to be determined, such analyses may help to the early detection of malignant hepatoma (primary liver carcinoma).