Neoplastic Alteration of a Membrane‐associated Sialidase of Rat Liver

Abstract

Rat liver participate fraction contains two types of membrane‐associated and gangliosides‐hydrolyzing sialidase, which have been shown to be identical to two membrane‐associated sialidases of rat brain (I and II) chromatographically, immunologically and in substrate specificity. Chromatography on AH‐Sepharose 4B of the membrane sialidases of rat primary hepatoma induced by 3′‐methyl‐4‐dimethylaminoazobenzene (MeDAB) further revealed that hepatocarcinogenesis induces a marked decrease in sialidase II but no decrease in sialidase I. Using antisera against sialidases I and II of rat brain, immunoprecipitation studies of the solubilized particulate fractions of rat liver and MeDAB‐hepatoma gave results similar to those obtained chromatographically. Using the same immunological technique, sialidase II but not sialidase I was found to be decreased in AH109 A hepatoma and in regenerating and fetal liver.

Aberrant expression of sialidase and cancer progression

“…Using a differential assay procedure for each form, we observed that intra-lysosomal and membrane-bound sialidase activities were elevated, whereas cytosolic sialidase activity was reduced, in rat hepatomas as compared with normal liver. 52) In mouse epidermal JB6 cells exposed to TPA and in anchorage-independent transformants, we also found lysosomal sialidase activity to be decreased while plasma membrane-associated sialidase activity was increased as compared with that in untreated JB6 cells. 53) Reduction in lysosomal sialidase also occurred in rat 3Y1 fibroblasts after src-transformation, levels of activity inversely correlating with the metastatic potential.…”

Glycan gene expression signatures in normal and malignant breast tissue; possible role in diagnosis and progression

“…A more recent study demonstrated that high level of the plasma membrane sialidase ( NEU3 ) was linked to protection from apoptosis in colon cancer (Kakugawa et al., 2002). It has also been shown that activity of the lysosomal sialidase ( NEU1 ) appears to be enhanced in hepatomas in comparison to normal liver tissue, while the cytosolic sialidase ( NEU2 ) was generally less active in the malignant tissue (Miyagi et al., 1990, 1992). On the other hand, several studies have shown that sialidases might also possess anti‐metastatic properties (Kato et al., 2001; Miyagi et al., 1994; Sawada et al., 2002; Tokuyama et al., 1997), leaving the precise role for sialidases in tumor progression still to be explained.…”

Human sialidase as a cancer marker

“…Several rat tissues, including the liver and brain were found to contain all the four types of sialidases. Based on the sialidase multiplicity, using a differential assay procedure for each form of sialidase, we observed that while the activity of the plasma membrane-bound sialidase was elevated, that of cytosolic sialidase was reduced in rat hepatomas as compared with the activity levels in the normal liver [10]. In mouse epidermal JB6 cells exposed to TPA and in their anchorage-independent transformants, we found lysosomal sialidase activity to be decreased and plasma membraneassociated sialidase activity to be increased as compared with the corresponding activities in the untreated JB6 cells [11].…”