WT1 expression level and clinical factors in multiple myeloma.

Although Wilm's Tuomor gene (WT1) was first identified as a tumor suppressor gene for Wilm's tumor, WT1 overexpression has been detected in different malignant cell types including leukemia. Increased expression of WT1 in acute leukemia is potentially used as a marker of minimal residual disease. However, the significance of the gene for multiple myeloma is still not clear. To determine the clinical relevance of WT1 expression in multiple myeloma, we examined the association of clinical parameters and WT1 expression in bone marrow for 17 newly diagnosed multiple myeloma patients. WT1 was assessed by real-time quantitative polymerase chain reaction (RQ-PCR) and calculated standardized WT1 expression level per 100 plasma cells in the bone marrow specimen as "corrected WT1". The expression of standardized WT1 and corrected WT1 in myeloma was 59 to 1,600 copies/microg RNA and 0.05 to 406.3 copies/microg RNA/100 plasma cells, respectively, lower than in leukemia. WT1 transcripts increased when clinical factors worsen, including the stage, amount of M protein, Hb, platelet count, blood urea nitrogen (BUN), creatinine, serum alkaline phosphatase (ALP), calcium, beta2-microglobulin, thymidine kinase activity (TK), and C-reactive protein (CRP). In conclusion, the expression level of WT1 could be an additional marker to the standard parameters considered in risk assessment for multiple myeloma.

Enzymatic properties of sialidase from the ovary of the starfish, Asterina pectinifera.

A sialidase [EC 3.2.1 18] was isolated and highly purified from the ovary of the starfish, Asterina pectinifera, and its enzymatic properties were compared with those of human placental sialidase. The final preparation gave one broad protein band corresponding to sialidase activity on polyacrylamide gel electrophoresis. The molecular weight of the enzyme was 360000 by HPLC on Sigma Chrome GFC-1300 and Sephadex G-150 column chromatography, and 55000 by SDS-PAGE, suggesting the presence of a hexamer in the native protein. The optimum pH was between 3.0 and 4.0, and the enzyme liberated sialyl residues from the following compounds: alpha(2-3) and alpha(2-6) sialyllactose, colominic acid, fetuin, transferrin, gangliosides GM3, GD1a and GD1b. The enzyme was strongly inhibited by 4-aminophenyl and methyl thio-glycosides of sialic acid, but not by those glycosides of 5-amino sialic acid or sialic acid methyl ester. The enzyme was also highly inhibited by sulfated glucan and glycosaminoglycans. The substrate specificity and the effects of inhibitors on starfish sialidase were very similar to those of human placental sialidase.

Purification and characterization of sialidase from porcine liver.

Sialidase [E.C.3.2.1.18] has previously been purified from porcine liver by procedures including extraction, ammonium sulfate precipitation, concanavalin A-Sepharose adsorption, activation, CM-Sepharose ion exchange chromatography, and HPLC on a Shim pack Diol 300 column. Two sialidase preparations, sialidase I and II, were obtained by CM-Sepharose column chromatography and were eluted with pH 4.5 and 5.0 buffers, respectively. The two enzyme preparations showed the same optimum pH, pH stability, and specificities for natural substrates. The two final preparations contained beta-galactosidase activity and showed three protein components of 64, 30, and 21 kDa with sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which are derived from the beta-galactosidase multimer. The anti-beta-galactosidase multimer antiserum was able to precipitate sialidase activity. It is likely that porcine liver sialidase exists as a multienzyme complex with beta-galactosidase and carboxypeptidase (protective protein).