The asialoglycoprotein receptor in human hepatocellular carcinomas: its expression on proliferating cells

Abstract

The asialoglycoprotein receptor (ASGP-R) is a glycoprotein present in large amount only on hepatocytes where it is expressed on the sinusoidal and lateral plasma membrane (Morell et al, 1968;Geffen and Spiess, 1992). ASGP-R binds and internalizes a broad range of molecules exposing galactose or N-acetyl-galactosamine residues. Following internalization the fate of ligand is lysosomal degradation (Morell et al, 1968;Geffen and Spiess, 1992).Taking advantage of this receptor a chemotherapeutic approach has been developed to reduce the extrahepatic side-effects of nucleoside analogues (NAs) used in chronic viral hepatitis (Fiume et al, 1979(Fiume et al, , 1997 Torriani et al, 1996). These drugs are coupled to galactosyl-terminating peptides. The conjugates selectively enter hepatocytes, where the lysosomal enzymes split the bond between the carrier and the drug, which becomes concentrated in liver cells. A similar strategy was suggested in order to increase the chemotherapeutic index of drugs inhibiting DNA synthesis in the treatment of human hepatocellular carcinoma (HCC) (Schneider et al, 1984;O'Hare et al, 1989;Di Stefano et al, 1998). This approach obviously requires the presence of the receptor in the neoplastic tissue and maintenance of its expression on DNA synthesizing cells.Few and conflicting data are available on the distribution of ASGP-R in human neoplastic hepatocytes. In a study in which the receptor was measured by a biochemical procedure, it was not found in HCC samples (Sawamura et al, 1984), whereas in an immunohistochemical investigation carried out on ten cases of HCC the presence of the receptor was demonstrated in the more differentiated forms (Hyodo et al, 1993). In the present study we have first assessed the frequency of ASGP-R expression in a large number of human HCCs. For this purpose, needle biopsy samples of sixty consecutive HCCs were analysed. Visualization of the receptor was obtained using an anti-ASGP-R monoclonal antibody applied after antigen retrieval procedure to routinely formalinfixed, paraffin-embedded liver samples. Since we found that the ASGP-R was present in 33 HCCs we also investigated whether the ASGP-R was maintained on the plasma membrane of DNA synthesizing cancer cells. For this purpose we incubated HCC tissue samples with bromodeoxyuridine (BrdU). The presence of ASGP-R on DNA-synthesizing cancer cells was immunohistochemically assessed using anti-BrdU and anti-ASGP-R antibodies on the same tissue section. Summary The expression of the asialoglycoprotein receptor (ASGP-R) on human hepatocellular carcinoma (HCC) cells might be exploited to reduce the extrahepatic toxicity of DNA synthesis inhibitors by their conjugation with galactosyl-terminating peptides. In the present study we first assessed the frequency of ASGP-R expression in 60 HCCs. Secondly, we investigated whether the receptor was maintained on the plasma membranes of DNA synthesizing cancer cells. Needle biopsies of HCC were evaluated. Diagnosis and grading of HCC were performed on routine haematoxyli...

Inhibition of hepatocarcinoma by systemic delivery of Apoptin gene via the hepatic asialoglycoprotein receptor

“…It has been reported that various proliferating HCCs express ASGPR on their surface, 22 which implies that systemic delivery of Asor-Apoptin can be potentially applied for many HCC patients. Recently, first clinical…”

Expression of Asialoglycoprotein Receptor 1 in Human Hepatocellular Carcinoma

“…Hyodo (Hyodo et al 1993) studied ASGPR distribution in HCC using traditional IHC staining and immunoelectron microscopy techniques and found ASGPR was membrane-localized in four of six well-differentiated HCCs; there was no ASGPR surface expression in two well-differentiated and four of four poorly differentiated HCCs. Trere and colleagues (Trere et al 1999) They also identified that ASGPR-expressing HCCs contain BrdU incorporation signals, indicating the proliferating property of the tumor cells. While our data are consistent with a trend towards an inverse correlation between expression and tumor differentiation, it is important to note that we observed very high H-scores (>200) for eight Grade III HCCs.…”

“…While it is well established that ASGPR is highly expressed on normal hepatocytes, the expression pattern of this receptor in early and advanced HCC patients has only been investigated in very small sample sets thus far (Hyodo et al 1993;Trere et al 1999;Julyan et al 1999;Seymour 2002). Therefore, we examined ASGPR1 expression pattern and levels in normal liver and different grades of HCC, taking advantage of tissue microarray technology to probe a relatively large sample size.…”

Construction and characterization of an anti‐asialoglycoprotein receptor single‐chain variable‐fragment‐targeted melittin

“…The asialoglycoprotein receptor (ASGPR), which has a high affinity for galactose-terminating triantennary N-linked heteroglycans of asialoglycoproteins, is expressed much higher in HCC cells than in normal liver cells [6], [7]. The capacity of this receptor to import large molecules across the cellular plasma membrane makes it a preferred target for receptor-mediated drug delivery to hepatocytes and hepatoma cells via ASGPR-mediated endocytosis [8][9][10].…”