Ligandinemia in primary liver cell cancer in rat and man

Variability of Glutathione S-Transferase α in Human Liver and Plasma

Background: Glutathione S-transferases are a family of enzymes involved in the binding, transport, and detoxification of a wide variety of endogenous and exogenous compounds. Little information is available about the variability of class α glutathione S-transferases in human liver, where they are highly expressed, or in serum.

Methods: Both total class α glutathione S-transferase (GST-α, composed of GSTA1-1, GSTA1-2, and GSTA2-2) as well as GSTA1-1 concentrations were measured by specific and sensitive ELISA in liver cytosols of 35 organ donors and in plasma samples of 350 healthy controls.

Results: The mean total GST-α and GSTA1-1 in liver cytosols were 25.1 ± 9.4 and 10.7 ± 5.3 μg/mg protein, respectively, and did not correlate with activities of aspartate aminotransferase or alanine aminotransferase. The mean total GST-α in liver was significantly higher in females compared with males (28.8 ± 10.0 vs 22.0 ± 7.8 μg/mg protein; P <0.05). In contrast, the median total GST-α in plasma was lower in females compared with males (2.0 and 2.8 μg/L, respectively; P <0.0001). The median ratios for GSTA1-1/total GST-α in liver and plasma were 0.42 and 0.58, respectively.

Conclusions: GSTA1-1 constitutes approximately one-half of the total amount of α class GSTs in human plasma and liver. Total GST-α values are higher in female liver but lower in plasma compared with the respective values in males.

A review of new approaches to assessing hepatic function in animals

Although a multitude of effective liver function tests are available for use in animals, a variety of modifications of currently used tests have been recently reported. In addition, newer procedures now used in human medicine may also provide unique insights into assessing and detecting acquired hepatic disorders in animals. Examples of new procedures are: assessing microsomal mixed function oxidase activity by plasma caffeine clearance; estimating the extent of active hepatic fibrogenesis through serum procollagen-III peptide levels; determining hepatic blood flow and functional mass by the galactose elimination capacity; detecting primary hepatocellular cancer through serum or urinary ligandin levels; and to estimate the liver's maximal capacity to excrete indocyanine green independent of blood flow. In evaluating drugs as to their hepatotoxicity, function tests should be included in the liver profile which measure specific metabolic alterations unique to the compound under study.

Alteration of hepatic glutathione S-transferases and release into serum after treatment with bromobenzene, carbon tetrachloride, or N-nitrosodimethylamine

The effects of bromobenzene, carbon tetrachloride, and N-nitrosodimethylamine (DMN) on hepatic glutathione S-transferase activity were studied in untreated and in phenobarbital- or ethanol-treated rats. In phenobarbital-treated rats, the isozymic composition of the hepatic cytosolic glutathione S-transferases was changed after giving hepatotoxic chemicals; glutathione S-transferases 2-2(AA), 3-3(A), 1-2(B), 3-4(C), and 4-4 + 5-5(D + E) were present in cytosol from control rats, but only glutathione S-transferases cochromatographing with transferases 4-4 + 5-5(D + E) were detected in rats given carbon tetrachloride or bromobenzene. A marked decrease in hepatic and an increase in serum glutathione S-transferase activity were also observed after carbon tetrachloride or bromobenzene treatment, but little change was seen after giving DMN. On the contrary, in untreated or ethanol-treated rats, DMN administration decreased hepatic glutathione S-transferase activity and caused an elevation in serum glutathione S-transferase activity. The isozymic composition of the hepatic cytosolic glutathione S-transferases after giving DMN to untreated rats was also altered, but the alteration was much less than that observed after giving carbon tetrachloride or bromobenzene to phenobarbital-treated rats. The elevation in serum glutathione S-transferase activity was accompanied by an increase in both serum glutamate-pyruvate transaminase activity and serum bilirubin concentrations. Thus, hepatic glutathione S-transferase activity was altered and released into serum after giving hepatotoxic chemicals, and the alteration in glutathione S-transferase activity was dependent on treatment with phenobarbital or ethanol.

Glutathione S-transferase in human hepatocellular carcinoma

Qualitative and quantitative changes in glutathione S-transferase (GSH-T) were studied in human hepatocellular carcinoma. GSH-T specific activity (mumoles per min per mg protein) was variably reduced in hepatocellular carcinoma. Similar changes were seen in "cationic" GSH-T (ligandin) concentration determined by radioimmunoassay. Immunohistochemical studies with antihuman liver ligandin suggest that positive staining was more frequently found in well-differentiated tumors. The relative activities of "cationic," "neutral," and "anionic" transferases (pI greater than 7.5) activity ranged from virtually absent to near normal values. "Neutral" (pI 6 to 6.5) and "anionic" (pI less than 5.4) species were present more often in tumors than in normal liver. In two cases, normal liver tissue and tumor were obtained from the same patient. In one, only quantitative differences were present, while in the other "cationic" and "neutral" GSH-Ts were present in the normal liver tissue while both "cationic" and "anionic" species were found in the tumor. Our studies indicate that qualitative as well as quantitative changes of GSH-T occur in human hepatocellular carcinoma.

Radioimmunoassay of human ligandin

A sensitive and specific radioimmunoassay for human ligandin has been developed and used to study ligandin release into the serum in acute and chronic hepatitis. Serum ligandin concentrations were elevated in 67 of 68 cases of acute viral hepatitis. Ligandin levels frequently returned to normal within the first 2 weeks of illness. The rapid disappearance of ligandin preceded the return to normal of serum SGOT. In chronic active hepatitis, serum ligandin levels correlated significantly (p less than 0.01) with histologic severity of disease. This correlation was not seen with SGOT. Serum ligandin may be useful in monitoring progress and the need for therapy in chronic active hepatitis.